PDF in Oftalmologia in italiano/inglese (articoli presenti: 1111)

Differences in Central Corneal Thickness between Spectral Domain-Optical Coherence Tomography and Ultrasound Pachymetry in Patients with Dry Eye Disease

Purpose. 

To compare central corneal thickness (CCT) values via Spectral Domain-Optical Coherence Tomography (SD-OCT) and ultrasonic pachymetry in patients with severe dry eye disease (DED) to determine the level of agreement between these 2 methods.

Methods.
The paired samples 𝑡-test asused to compare CT value sin severe DED patients. Matching analysis between methods was performed using intraclass correlation coefficient (ICC). 


Intrasession reliability of the measurement methods was calculated via the concordance correlation coefficient(CCC), variation equivalent, and Pearson’scor relation coefficient. The Bland Altman procedure was used tographically represent the differences between CCT values.

Results.
The study included 56 eye sof 24 female and 4 male patients. Mean age of the patient swas 50.9 ± 11.3 years. Mean CCT via CirrusSD-OCT was  523.82 ± 30.98 𝜇m versus 530.050 ± 31.85 𝜇m via ultrasonic pachymetry (paired samples 𝑡-test, 𝑃 < 0.001). The Bland-Altman plot showed good agreement between the examiners. The ICC for repeatability was 0.974. The CCC between the 2 methods ’CCT values was 0.973. The variation equivalent was 0.976 and Pearson’scor relation coefficient was 99.3%, which also indicated high correlation between the 2 methods’ measurements.

Conclusions. 
The present findings show that inpatient swith severe DED Cirrus SD-OCT provides reliable intraobserver CCT values.  


Differences in Central Corneal Thickness between Spectral Domain-Optical Coherence Tomography and Ultrasound Pachymetry in Patients with Dry Eye Disease


Area Tematica : cornea

Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness a very early ectasia prognostic factor

Purpose: To determine and correlate epithelial corneal thickness (pachymetric) measurements taken with a digital arc scanning very high frequency ultrasound biomicroscopy (HF UBM) imaging  system (Artemis-II), and compare mean and central epithelial thickness among normal eyes, untreated keratoconic eyes, and keratoconic eyes previously treated with collagen crosslinking (CXL).


Methods: Epithelial pachymetry measurements (topographic mapping) were conducted on 100 subjects via HF UBM. Three groups of patients were included: patients with normal eyes (controls), patients with untreated keratoconic eyes, and patients with keratoconic eyes treated with CXL. Central, mean, and peripheral corneal epithelial thickness was examined for each group, and a statistical study was conducted. 

Results: Mean, central, and peripheral corneal epithelial thickness was compared between the three groups of patients. Epithelium thickness varied substantially in the keratoconic group, and in some cases there was a difference of up to 20 µm between various points of the same eye, and often a thinner epithelium coincided with a thinner cornea. However, on average, data from the keratoconic group suggested an overall thickening of the epithelium, particularly over the pupil center of the order of +3 µm, while the mean epithelium thickness was on average +1.1 µm, compared to the control population (P = 0.005). This overall thickening was more pronounced in younger patients in the keratoconic group. Keratoconic eyes previously treated with CXL showed, on average, virtually the same average epithelium thickness (mean -0.7 µm, -0.2 µm over the pupil center, -0.9 µm over the peripheral zone) as the control group. This finding further reinforces our novel theory of the “reactive” component of epithelial thickening in corneas that are biomechanically unstable, becoming stable when biomechanical rigidity is accomplished despite persistence of cornea topographic irregularity.

Conclusion: A highly irregular epithelium may be suggestive of an ectatic cornea. Our results indicate that the epithelium is thinner over the keratoconic protrusion, but to a much lesser extent than anticipated, and on average epithelium is thicker in this group of patients. This difference appears to be clinically significant and may become a screening tool for eyes suspected for ectasia. Keywords: corneal pachymetry, ectasia, keratoconus screening, cornea epithelial thickness.


Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness a very early ectasia prognostic factor


Area Tematica : cornea

ARVO 2016


ARVO 2016


Area Tematica : oct

The Use of Bowman’s Layer Vertical Topographic Thickness Map in the Diagnosis of Keratoconus


Purpose—To evaluate the use of Bowman’s layer (BL) vertical topographic thickness maps in diagnosing keratoconus (KC).
Design—Prospective, case control, interventional case series.

Participants—42 eyes; 22 eyes of 15 normal subjects and 20 eyes of 15 KC patients.

Intervention—BL 2-dimensional 9 mm vertical topographic thickness maps were created using custom-made ultra high-resolution optical coherence tomography.

Main Outcome Measures—BL average and minimum thicknesses of the inferior half of the cornea, Bowman’s ectasia index (BEI; defined as BL minimum thickness of the inferior half of the cornea divided by BL average thickness of the superior half of the cornea multiplied by 100), BEIMax (defined as BL minimum thickness of the inferior half of the cornea divided by BL maximum thickness of the superior half of the cornea multiplied by 100), KC patients’ Keratometric astigmatism (Ast-K) and average keratometric readings (Avg-K).

Results—In KC patients, BL vertical thickness maps disclosed localized relative inferior thinning of the BL. Inferior BL average thickness (normal=15±2, KC=12±3 μm), inferior BL minimum thickness (normal=13±2, KC=7±3 μm), BEI (normal=91±7, KC=48±14) and BEI-Max (normal=75±8; KC=40±13) all showed highly significant differences in KC compared to normal subjects (P<0.001). Receiver-operating characteristics (ROC) curve analysis showed excellent predictive accuracy for BEI and BEI-max with 100% sensitivity and specificity (area under the curve or AUC of 1) with cut-off values of 80 and 60, respectively. AUC of inferior BL average thickness and minimum thickness were 0.87 and 0.96 with sensitivity of 80% and 93%, respectively and specificity of 93% and 93%, respectively. Inferior BL average thickness, inferior BL minimum thickness, BEI and BEI-Max correlated highly to Ast-K (R=−0.72; −0.82; −0.84 and −0.82, respectively; P<0.001) and to Avg-K (R=−0.62; P<0.001, R=−0.59; P=0.001, R=−0.60; P<0.001 and R=−0.59, P=0.001, respectively).

Conclusions—BL vertical topographic thickness maps of KC patients disclose characteristic localized relative inferior thinning. Inferior BL average thickness, inferior BL minimum thickness, BEI and BEI-max are qualitative and quantitative indices for the diagnosis of KC that accurately correlate with the severity of KC. In our pilot study, BEI and BEI-max showed excellent accuracy, sensitivity and specificity in the diagnosis of KC


The Use of Bowman’s Layer Vertical Topographic Thickness Map in the Diagnosis of Keratoconus


Area Tematica : cornea

Corneal surgery in keratoconus: which type, which technique, which outcomes?

Abstract

Keratoconus is a disease characterized by progressive thinning, bulging, and distortion of the cornea. Advanced cases usually present with loss of vision due to high irregular astigmatism. A majority of these cases require surgical intervention. This review provides an update on the current treatment modalities of corneal surgery available for the management of advanced corneal ectasias. 

Keywords: Keratoconus, Deep anterior lamellar keratoplasty, Penetrating keratoplasty, Corneal transplant, Rejection


Corneal surgery in keratoconus: which type, which technique, which outcomes?


Area Tematica : cornea

Comparison of Fourier-Domain ad Time-Domain Optical Coherence Tomography in the Measurement of Thinnest Corneal Thickness in Keratoconu

Objective. 

To compare fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT (TD-OCT) in the determination of thinnest corneal thickness(TCT).

Methods.This study included 55 keratoconus patients and 50 healthy volunteers. The RTVue-OCT (FD-OCT) and Visante-OCT (TD-OCT) were used for the measurement of the TCT. Three consecutive scans were performed. The comparison and agreement between the two modalities were analyzed by pairedt-test, the Pearson correlation, intraclass correlation coefficient (ICC), and Bland-Altman plots.  intraobserver repeatability was analyzed by the intraobserver within-subjects tandard deviation (𝑆(𝑤)), coefficient of variation (CV(𝑤)), and ICC.

Results.
The TCT value of normal  corneas was higher by RTVue-OCT (530.4±19.7𝜇m) than Visante-OCT (521.5±18.3𝜇m)(𝑝 < 0.001).
For keratoconus eyes, the TCT was 425.0 ±58.2𝜇m and 424.4±55.7𝜇m (differencebeing0.6±10.2𝜇m,𝑝 = 0.604). Strong correlation (r=0.938∼0.985) (ICC=0.915–0.984) was observed between the two OCTs, and each OCT exhibited excellent repeatability indetermining the TCT inallsubjects (ICC= 0.984–0.994).

Conclusions.

The values of TCT obtained from RTVue-OCT and Visante-OCT were highly correlated; however, the two values were different. Both OCT instruments exhibited good intraobser verreliability.
The existence of systematic differences suggested that the two instruments cannot be used interchangeably.


Comparison of Fourier-Domain ad Time-Domain Optical Coherence Tomography in the Measurement of Thinnest Corneal Thickness in Keratoconu


Area Tematica : cornea

Age-Related Changes in Human Corneal Epithelial Thickness Measured With Anterior Segment Optical Coherence Tomography

PURPOSE. To measure corneal and limbal epithelial thickness (ET) in normal subjects and to evaluate its variation with age by using anterior segment optical coherence tomography (ASOCT). 


METHODS. A total of 180 normal subjects (180 healthy eyes) were enrolled and divided into four groups according to age: A (0–20 years), B (21–40 years), C (41–60 years), and D (>60 years). Cornea and limbus were imaged with OCT. Corneal ET (CET) was obtained automatically by the built-in analysis software of the OCT system. Limbal ET (LET) in four quadrants was manually measured from OCT images. 

RESULTS. Corneal ETof a central 2-mm diameter zone in groups A, B, C, and D were 53.4 6 2.8 lm, 53.4 6 2.7 lm, 53.2 6 3.0 lm, and 52.9 6 3.3 lm, respectively, N showing no significant change with aging. In the paracentral zone extending to 6-mm diameter, correlation analysis suggested that CET was inversely associated with age (P < 0.05). Limbal ET in the nasal and the temporal quadrants were similar and decreased with aging, the averages were 58.3 6 8.1 lm, 54.1 6 6.1 lm, 51.2 6 6.1 lm, 51.6 6 5.2 lm for groups A, B, C and D, respectively; while age seemed to have no effect on LET of the superior and the inferior quadrant.

CONCLUSIONS. The paracentral corneal epithelium, as well as the nasal and temporal limbal epithelium, became thinner with aging, while the central CET seemed to remain constant. Measurement with AS-OCT of the corneal and limbal ET could aid in clinical assessment and planning treatments of the cornea.

Keywords: corneal epithelium, limbus, aging, optical coherence tomograph.


Age-Related Changes in Human Corneal Epithelial Thickness Measured With Anterior Segment Optical Coherence Tomography


Area Tematica : cornea

A NOVEL METHOD OF OBJECTIVE TESTING IN DED

Epidemiologic studies estimate that the prevalence of dry eye disease (DED) is as much as 25% in the general population.1,2 Significantly associated with aging, DED occurs most frequently in those over the age of 45 years.3 It is more prevalent in women compared with men.4-6 Contributing factors to DED may be classified as ocular, medical, pharmaceutical, iatrogenic, environmental, and contact–lens-related.


A NOVEL METHOD OF OBJECTIVE TESTING IN DED


Area Tematica : congiuntiva

Comparison of Corneal Epithelial Thickness Measurement Between Fourier-Domain OCT and Very High-Frequency Digital Ultrasoun

Abstract PURPOSE—To compare measurements of corneal epithelial thickness using optical coherence tomography (OCT) and very high-frequency digital ultrasound (VHFDU).

METHODS—Retrospective analysis of 189 virgin corneas and 175 post-laser refractive surgery (LRS) corneas that had corneal epithelial thickness measurement with RTVue Fourier-domain OCT (Optovue, Inc., Fremont, CA) (tear film included) and Artemis VHFDU (ArcScan Inc., Morrison, CO) (tear film excluded). Averages were calculated for the central 2-mm diameter zone and for two further concentric annuli of 1.5- and 0.5-mm width, each divided into eight sectors
Agreement was analyzed by mean difference (OCT – VHFDU), 95% limits of agreement (LoA) (1.96 standard deviation of the difference), and Bland–Altman analysis.

RESULTS—In virgin epithelium, mean central thickness was 53.4 ± 3.20 μm (range: 46 to 62 μm) with OCT and 54.1 ± 2.96 μm (range: 48 to 61 μm) with VHFDU; OCT measured thinnest in 70% with a mean difference of −0.71 μm (95% LoA of ±3.94 μm, P < .001). In post-LRS epithelium, mean central thickness was 57.9 ± 6.08 μm (range: 42 to 77 μm) with OCT and 60.5 ± 6.47 μm (range: 42 to 79 μm) with VHFDU; OCT measured thinnest in 88%, with a mean difference of −2.48 μm (95% LoA of ±5.33 μm, P < .001). A larger difference between methods was more common with thicker epithelium.

CONCLUSIONS—Corneal epithelial thickness measurements using OCT were found to be slightly thinner than for VHFDU. In contrast to VHFDU, OCT measurement includes the tear film, so the true difference is probably approximately 4 μm more than reported. The difference was greatest inferiorly and higher for post-LRS eyes and in thicker epithelium.


Comparison of Corneal Epithelial Thickness Measurement Between Fourier-Domain OCT and Very High-Frequency Digital Ultrasoun


Area Tematica : cornea

Strategies for improving the early diagnosis of keratoconu

Abstract: To diagnose keratoconus at its earliest stage is meaningful in order to avoid refractive surgery in the eye, which may lead to further damage in the abnormal cornea structure and consequently cause iatrogenic ectasia.


In this article, the following aspects of detecting earliest stage of keratoconus were reviewed: 1) nomenclature of the earliest forms of keratoconus; 2) diagnosis of keratoconus using curvature-based topography (also known as Placido-based topography, ie, videokeratography) as a traditional method and elevationbased topography as a new method which has gained popularity in recent years; and 3) other methods analyzing keratoconus cornea like corneal biomechanics and wavefront sensing.

Elevation-based topography using either Scheimpflug imaging techniques or slit-scanning imaging techniques has shown to be advantageous over the curvature-based topography in detecting keratoconus at its earliest stage. Posterior elevation of the cornea is notified to enhance the sensitivity and specificity of detection if used along with the measurements of anterior surface of the cornea. 

Cornea biomechanics analysis and wavefront sensing also revealed differences between normal eyes and keratoconic eyes in their earliest stage. Combining the latest technology and the traditional techniques will be the future trend to improve early diagnosis of keratoconus. Keywords: keratoconus, early diagnosis, Scheimpflug imaging, slit-scanning imaging, wavefront error, corneal biomechanics.


Strategies for improving the early diagnosis of keratoconu


Area Tematica : cornea

Penetrazione dell'indometacina


Penetrazione dell'indometacina


Area Tematica : cataratta

Expanded Spectrum of Congenital Ocular Findings in Microcephaly with Presumed Zika Infection


Expanded Spectrum of Congenital Ocular Findings in Microcephaly with Presumed Zika Infection


Area Tematica : cataratta

Errors Associated to Keratoconus


Errors Associated to Keratoconus


Area Tematica : cornea

Ocular Pharmacokinetics Profile of Different Indomethacin Topical Formulation

Abstract

Purpose: This study evaluated the ocular pharmacokinetics of indomethacin following topical administration of two different formulations present in the market. Methods: Rabbits received a multiple topical instillation (30mL) of indomethacin ophthalmic suspension containing hydroxypropylmethylcellulose (IND-HPMC; Indom Alfa-Intes) or indomethacin ophthalmic solution with hydroxypropyl-b-cyclodextrin (IND-CD; Indocollirio Bausch & Lomb). Aqueous humor, vitreous humor, and retina were collected from animals at fixed time intervals after dosing. Indomethacin ocular levels were measured by liquid chromatography mass spectrometry (LC-MS/MS), and the pharmacokinetic parameters— peak drug concentration (Cmax), time to peak value (Tmax), and area under the concentration–time curve between 0 and 240min (AUC0–240)—were determined. All of the animals were treated according to the Association for Research in Vision and Ophthalmology (ARVO) Statement for the Use of Animals in Ophthalmic and Vision Research. 

Results: Peak concentrations of indomethacin in aqueous and vitreous were achieved within 30min and 60min after a single instillation of IND-HPMC and IND-CD, respectively. Retinal Tmax was 30min and 120min in the IND-HPMC-treated group and the IND-CD-treated group, respectively. Higher levels of indomethacin were foundinretinaafterIND-HPMCadministrationcomparedtoIND-CD(AUC0–240 272.9ng/gperminvs.AUC0–240 73.5ng/g/min, respectively; P<0.01). Also in the aqueous and vitreous, the drug levels were statistically higher (P<0.01) in the IND-HPMC group in comparison with the IND-CD group (AUC0–240 2039ng/mL per min vs. AUC0–240 427.3ng/mL per min, AUC0–240 53.8ng/mL per min vs. AUC0–240 12.5ng/mL per min, respectively). The highest drug levels in the ocular tissues were found following IND-HPMC administration compared with IND-CD (retina: Cmax 73.7–6.4ng/g vs. 25.5–1.73ng/g; aqueous: Cmax 952–6.8ng/mL vs. 163–4.1ng/mL; vitreous Cmax 31–3.5ng/mL vs. 6.37–3.6ng/mL).

 Conclusions: IND-HPMC treatment demonstrates a nonclinical ocular pharmacokinetic profile of indomethacin characterized by higher concentrations of drug in ocular tissues (4.7-, 4.3- and 3.7-fold higher in aqueous, vitreous, and retina, respectively) compared to the ND-CD-treated group. Taken together, these data seem to indicate that IND-HPMC formulation has good ocular distribution reaching relevant indomethacin levels in the back of the eye, and suggest that this formulation may be very useful for clinicians to manage retinal conditions.


Ocular Pharmacokinetics Profile of Different Indomethacin Topical Formulation


Area Tematica : cataratta

Preoperative topical indomethacin to prevent pseudophakic cystoid macular edema

PURPOSE: To evaluate the effectiveness of a nonsteroidal antiinflammatory drug (NSAID) on pseudophakic
cystoid macular edema (CME) and determine the efficacy when used preoperatively and
after uneventful phacoemulsification surgery.

SETTING: Department of Ophthalmology, Kocatepe University, School of Medicine, Afyonkarahisar,
Turkey.

METHODS: One hundred seventy-nine eyes of 189 patients having uneventful phacoemulsification
surgery were enrolled in the study. After surgery, all patients used topical steroids and antibiotics 4
times daily. Sixty-one eyes, chosen randomly, received a topical NSAID (indomethacin) 4 times
daily for 3 days preoperatively and 1 month postoperatively. Sixty eyes received topical indomethacin
4 times daily for 1 month postoperatively. Fifty-eight eyes served as a control group and received
only topical steroids and antibiotics. At the third postoperative month, visual acuity,
fluorescein angiograms, and macular thresholds were evaluated. Statistical analysis was by chisquare
and 1-way analysis of variance tests.

RESULTS: Cystoid macular edema was not seen in the group receiving indomethacin preoperatively
and postoperatively. The incidence of angiographic CME was 15.0% in the group receiving postoperative
indomethacin and 32.8% in the control group (P<.001). Mean sensitivity in the macular
threshold test did not show a significant change between groups (P Z .83). Postoperative visual
acuity was significantly higher in the group receiving preoperative indomethacin (P<.001).

CONCLUSION: Nonsteroidal antiinflammatory drugs decreased the incidence of CME, and their efficacy
increased when begun preoperatively


Preoperative topical indomethacin to prevent pseudophakic cystoid macular edema


Area Tematica : cataratta

Focal Point: Diagnostica Corneale


Focal Point: Diagnostica Corneale


Area Tematica : cornea

Indom versus altri FANS


Indom versus altri FANS


Area Tematica : cataratta

Farmacocinetica dell'indometacina


Farmacocinetica dell'indometacina


Area Tematica : cataratta

Clinica comparison for Indometacina


Clinica comparison for Indometacina


Area Tematica : cataratta

Quantitative analysis of iris parameters in keratoconus patients using optical coherence tomography

ABSTRACT
Purpose: To investigate the relationship between quantitative iris parameters
and the presence of keratoconus.

Methods: Cross-sectional observational study that included 15 affected eyes of
15 patients with keratoconus and 26 eyes of 26 normal age- and sex-matched
controls. Iris parameters (area, thickness, and pupil diameter) of affected and
unaffected eyes were measured under standardized light and dark conditions
using anterior segment optical coherence tomography (AS-OCT). To identify optimal
iris thickness cutoff points to maximize the sensitivity and specificity when
discriminating keratoconus eyes from normal eyes, the analysis included the use
of receiver operating characteristic (ROC) curves.

Results: Iris thickness and area were lower in keratoconus eyes than in normal
eyes. The mean thickness at the pupillary margin under both light and dark conditions
was found to be the best parameter for discriminating normal patients from
keratoconus patients. Diagnostic performance was assessed by the area under the
ROC curve (AROC), which had a value of 0.8256 with 80.0% sensitivity and 84.6%
specificity, using a cutoff of 0.4125 mm. The sensitivity increased to 86.7% when
a cutoff of 0.4700 mm was used.

Conclusions: In our sample, iris thickness was lower in keratoconus eyes than
in normal eyes. These results suggest that tomographic parameters may provide
novel adjunct approaches for keratoconus screening.
Keywords: Tomography, optical coherence; Iris; Keratoconus; Cornea; Dilatation
pathologic; ROC curve


Quantitative analysis of iris parameters in keratoconus patients using optical coherence tomography


Area Tematica : cornea

Epithelial Thickness: An Indicator for Early Keratoconus?

Maps of the corneal epithelium can be valuable in
the decision-making process for excimer laser
corneal refractive surgery, in the assessment of
short- and long-term postoperative outcomes
and epithelial healing after corneal collagen crosslinking
(CXL), and in screening for keratoconus and pellucid marginal
degeneration (PMD). 

Reinstein et al have contributed
a large number of studies with ultrasound epithelial measurements
pointing out the plasticity of the epithelium in
keratoconic corneas; they have suggested that a thicker than
normal central cornea epithelium may suggest ectasia, as it
may reflect the thickening normalization response to inferior
steepening commonly seen in ectasia.

Current optically based corneal imaging systems have
limited capability to discern epithelial from stromal components
over the entire corneal area. On the other hand,
in vivo visualization of the epithelial layer over the stromal
bed can be achieved using the principle of reflecting an
elastic wave from the epithelium-stromal interface and
detecting its echo.1 Systems employing this technology are
known as scanning ultrasound biomicroscopes (UBMs).

We performed a study to explore the efficacy of a highfrequency
arc scanning ultrasound system, the Artemis 2+
superior (Arcscan, Inc.) in the task of clinical epithelial corneal
mapping in normal and keratoconic eyes. The study
included normal eyes, keratoconic eyes treated with the
Athens protocol, and keratoconic untreated eyes. 

The purpose was to examine whether overall increased epithelial.


Epithelial Thickness: An Indicator for Early Keratoconus?


Area Tematica : cornea

In pursuit of objective dry eye screening clinical techniques

Abstract
Dry eye is a multifactorial, progressive, and chronic disease of the tears and ocular surface. The disease is
multi-factorial and has intermittent symptoms. Discomfort, visual disturbance, tear film instability with potential
damage to the ocular surface, and increased tear film osmolarity are known associates.
Dry eye is a common clinical problem for eye-care providers worldwide and there is a large number of clinical
investigative techniques for the evaluation of dry eye. Despite this, however, there is no globally accepted guideline
for dry eye diagnosis and none of the available tests may hold the title of the ‘gold standard’. The majority of the
techniques involved in the diagnosis of the disease, particularly for its early stages, has a large degree of
subjectivity.
The purpose of this article is to review existing dry eye investigative techniques and to present a new objective dry
eye screening technique based on optical coherence tomography.

Keywords: Dry eye, Shrimer’s test, TBUT test, Inflammation, OCT, Epithelial thickness, Anterior-segment


In pursuit of objective dry eye screening clinical techniques


Area Tematica : congiuntiva

Tear Meniscus Analysis with Fourier-Domain Optical Coherence Tomography in Keratoconu

ABSTRACT Purpose: To measure the lower tear meniscus dynamics with Fourier domain-optical coherence tomography (FD-OCT) in keratoconus patients without dry eye findings to evaluate the effects of the corneal ectasia on lower tear meniscus parameters, and to determine the most affected meniscus variable from the corneal ectasia in keratoconus.


Methods: Prospective, clinical study. Forty-one eyes of 25 keratoconus patients without dry eye and 40 eyes of 20 healthy subjects were included. The lower tear meniscus analysis with FD-OCT, and corneal topography, keratometry, and pachymetry measurements were performed in all eyes. The main outcomes, including the lower tear meniscus height (TMH), depth (TMD), area (TMA), and angle between cornea and the tear meniscus (α-angle), were assessed. The results were compared between the patients and the control subjects.

Results: The average keratometric power was 53.94 ± 5.76 D (between 44.46 to 63.75 D) in keratoconic eyes. It was 43 ± 0.8 D (between 40.50 to 45.94 D) in the controls. The average TMH, TMD, and TMA values did not show any statistically significant difference between the patients and the controls (p  =  0.39, p  =  0.824, p  =  0.516, respectively). However, the average value of the α-angle was significantly higher in keratoconic eyes when compared to controls (p  =  0.031). It was positively correlated with the keratometric power (r = 0.577, p  =  0.001). 

Conclusions: The TMH, TMD, and TMA did not show any change with the corneal protrusion; however, the α-angle had positive correlation with the keratometric power in keratoconic eyes. Keywords: α-angle, Keratoconus, Fourier domain-optical coherence tomography, Tear meniscus area, Tear meniscus depth, Tear meniscus height


Tear Meniscus Analysis with Fourier-Domain Optical Coherence Tomography in Keratoconu


Area Tematica : congiuntiva

Research Article Ocular Surface Epithelial Thickness Evaluation in Dry Eye Patients: Clinical Correlations

Purpose. To evaluate the relationship between corneal and conjunctival epithelium thickness and ocular surface clinical tests in dryeyedisease(DED)patients.PatientsandMethods. Fifty-fourpatientswithDEDand32controlsubjectswereincluded.Each patient underwent an ocular surface evaluation using the ocular surface disease index (OSDI), tear film break-up time (TBUT), corneal and conjunctival staining, tear film lipid layer analysis, and Schirmer test. The central corneal (CET), limbal (LET), and bulbar conjunctival epithelium thickness (BET) were acquired using spectral-domain optical coherence tomography (SD-OCT). Results.Comparedtocontrolsubjects,meanBETwassignificantlythickerandmeanLETwassignificantlylowerintheDEDgroup. There was no significant difference in mean CET between the two groups. The mean LET was correlated with OSDI and TBUT. TheinferiorLETwascorrelatedwithOSDI,SchirmerItest,TBUT,Oxfordscore,andcornealsensitivity.MeanBETwascorrelated withOSDIandTBUT,butnotwithSchirmerItestandOxfordscore.Conclusions.Indryeyepatients,athinnerlimbalepithelium andathickerbulbarconjunctivalepitheliumwereobserved.Thesechangeswerecorrelatedtotheseverityofdryeyesymptomsand tearfilmalterations


Research Article Ocular Surface Epithelial Thickness Evaluation in Dry Eye Patients: Clinical Correlations


Area Tematica : cornea

Comparison of Corneal Epithelial and Stromal Thickness Distributions between Eyes with Keratoconus and Healthy Eyes with Corneal Astigmatism $2.0 D

Abstract

Purpose: To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain
optical coherence tomography (SD-OCT).

Patients and Methods: We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1) and in 20 healthy
subjects with corneal astigmatism $2 D (group 2). Epithelial and stromal thicknesses were measured at 11 strategic
locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry
superimposition was used in the statistical analysis.

Results: The mean maximum keratometry measurements in groups 1 and 2 were 47.962.9 D (range, 41.8–52.8) and
45.661.1 D (range, 42.3–47.5), respectively, with mean corneal cylinders of 3.362.2 D (range, 0.5–9.5) and 3.661.2 D (range,
2.0–6.4), respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.464.4 mm) at
1.2 mm inferotemporally and the highest (59.364.4 mm) at 1.4 mm supranasally from the corneal vertex. There was only a
small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups.
The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally
lower in group 1 than in group 2.

Conclusions: SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium
and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The
distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of
keratoconus.


Trial Registration: ClinicalTrials.gov NCT02023619


Comparison of Corneal Epithelial and Stromal Thickness Distributions between Eyes with Keratoconus and Healthy Eyes with Corneal Astigmatism $2.0 D


Area Tematica : cornea

An Accurate Method to Determine Bowman’s Layer Thickness In Vivo in the Human Cornea

PURPOSE.


 To determine an accurate value for Bowman’s layer (BL) thickness in vivo in humans.

METHODS. Seventeen corneal transplant patients were examined preoperatively by laser-scanning in vivo confocal microscopy (IVCM), and corneal buttons were removed postoperatively and sectioned for light microscopy (LM). Nine corneas with uniformly thick BL by LM were used for thickness measurement. 

In the uniformly thick samples, probable overestimation of BL thickness in vivo by a first in vivo method (Method 1) led to the development of a revised in vivo method (Method 2). Method 2 was used to measure BL thickness in 20 healthy volunteers. 

RESULTS. In nine patients, mean BL thickness prior to transplantation was 13.7 6 1.6 lm by IVCM (Method 1) while BL thickness of the removed corneal button was 9.7 6 1.7 lm by LM (P < 0.001). The correlation of BL thickness between IVCM (Method 1) and LM was poor (P ¼ 0.226). In 20 right eyes of 20 normal corneas, both in vivo methods were used to determine BL thickness.
 
Mean BL thickness by Method 1 was 13.2 6 1.6 
lm and by Method 2 was 9.1 6 1.4 lm (P < 0.001). BL thickness measurements by both in vivo methods were highly correlated (P < 0.001). 

CONCLUSION. BL thickness by a revised in vivo method was close to LM values in this study and to values reported in fixed tissue in other studies. 

The authors believe this revised method provides the most accurate estimates of BL thickness in vivo to date. (Invest Ophthalmol Vis Sci. 2012;53:2354– 2359) DOI:10.1167/iovs.11-8565


An Accurate Method to Determine Bowman’s Layer Thickness In Vivo in the Human Cornea


Area Tematica : cornea

ALCUNI SEGNI CLINICI CHE IDENTIFICANO IL CHERATOCONO

Gli anelli di Fleischer Gli anelli di Fleischer variano in termini di pigmentazione da un giallo-marrone ad un verde-oliva e possono, molto spesso, circondare la base del cono. Si formano quando il pigmento dell’emosiderina, deposito ferroso nella parte profonda dell’epitelio, e divengono molto fini tanto più avanzato è il cheratocono. Ad una ispezione corneale attenta di una cornea affetta da cheratocono possono evidenziarsi delle linee in almeno il 50% dei casi. Per localizzare gli anelli inizialmente può essere facile utilizzando un filtro cobalto e guardando attentamente sulla metà superiore dell’epitelio corneale evidenziati; una volta localizzati si potrà utilizzare la luce bianca per osservarne la loro estensione.


ALCUNI SEGNI CLINICI CHE IDENTIFICANO IL CHERATOCONO


Area Tematica : cornea

In pursuit of objective dry eye screening clinical techniques


In pursuit of objective dry eye screening clinical techniques


Area Tematica : cornea

Fourier-Domain Optical Coherence Tomography Imaging in Keratoconus A Corneal Structural Classification

Objective: To study corneal morphologic changes in a large keratoconic population and to establish a structural optical coherence tomography (OCT) classification. 


Design: Cross-sectional, observational study. 

Participants: A total of 218 keratoconic eyes from 218 patients and 34 eyes from 34 normal subjects. 

Methods: A Fourier-domain OCT system with 5-mm axial resolution was used. For each patient, 3 highresolution scans were made across the keratoconus cone. All scans were analyzed by keratoconus specialists who were not given access to patients’ clinical and topographic data, and who established an OCT classification. The reproducibility of the classification and its correlation with clinical and paraclinical characteristics of patients with keratoconus were evaluated. The OCT examinations were performed every 4 months to follow up structural corneal changes. 

Main Outcome Measures: Evaluation of the structural corneal changes occurring in keratoconus cases with various stages of severity based on OCT findings. 

Results: Fourier-domain OCT classification containing 5 distinct keratoconus stages is proposed. Stage 1 demonstrates thinning of apparently normal epithelial and stromal layers at the conus. Stage 2 demonstrates hyperreflective anomalies occurring at the Bowman’s layer level with epithelial thickening at the conus. Stage 3 demonstrates posterior displacement of the hyperreflective structures occurring at the Bowman’s layer level with increased epithelial thickening and stromal thinning. Stage 4 demonstrates pan-stromal scar. Stage 5 demonstrates hydrops; 5a, acute onset: Descemet’s membrane rupture and dilaceration of collagen lamellae with large fluid-filled intrastromal cysts; 5b, healing stage: pan-stromal scarring with a remaining aspect of Descemet’s membrane rupture. The reproducibility of the classification was very high between the corneal specialist observers. Clinical and paraclinical characteristics of keratoconus, including visual acuity, corneal epithelium and stromal thickness changes, corneal topography, biomechanical corneal characteristics, and microstructural changes observed on confocal microscopy, were concordant with our OCT grading. 

Conclusions: Optical coherence tomography provides an accurate assessment of structural changes occurring in keratoconus eyes. These changes were correlated with clinical and paraclinical characteristics of patients. The established classification not only allows structural follow-up of patients with keratoconus but also provides insight into the pathogenesis of keratoconus and treatment strategies for future research. 

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2013;-:1e10 ª 2013 by the American Academy of Ophthalmology.


Fourier-Domain Optical Coherence Tomography Imaging in Keratoconus A Corneal Structural Classification


Area Tematica : cornea

2 parte Advanced diagnostic tecnologies in keratoconus andcorneal ectatic disease


2 parte Advanced diagnostic tecnologies in keratoconus andcorneal ectatic disease


Area Tematica : cornea

Corneal Epithelium Thickness Profile in 614 Normal Chinese Children Aged 7–15

The purpose of the study is to describe the values and distribution of corneal epithelium thickness (CET) in normal Chinese school-aged children, and to explore associated factors with CET. CET maps were measured by Fourier-domain optical coherence tomography (FD-OCT) in normal Chinese children aged 7 to 15 years old from two randomly selected schools in Shanghai, China.


 Children with normal intraocular pressure were further examined for cycloplegic autorefraction, corneal curvature radius (CCR) and axial length. Central (2-mm diameter area), para-central (2- to 5-mm diameter area), and peripheral (5- to 6-mm diameter area) CET in the superior, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal cornea; minimum, maximum, range, and standard deviation of CET within the 5-mm diameter area were recorded.

 The CET was thinner in the superior than in the inferior and was thinner in the temporal than in the nasal. The maximum CET was located in the inferior zone, and the minimum CET was in the superior zone. A thicker central CET was associated with male gender (p=0.009) and older age (p=0.037) but not with CCR (p=0.061), axial length (p=0.253), or refraction (p=0.351) in the multiple regression analyses. CCR, age, and gender were correlated with para-central and peripheral CET


Corneal Epithelium Thickness Profile in 614 Normal Chinese Children Aged 7–15


Area Tematica : cornea

History of the development of the treatment of keratoconus


History of the development of the treatment of keratoconus


Area Tematica : cornea

Keratoconus

Keratoconus, (derived from the Greek terms kerato, meaning horn, cornea, and konos meaning cone) is a degenerative, non-inflammatory disorder of the cornea. 

It is characterised by central and para-central corneal stromal thinning and subsequent conical ectasia. This conical distortion of the cornea results in irregular astigmatism with associated reduction in visual performance. It typically presents in adolescence and progresses in a variable manner.

 It was first described by British physician John Nottingham in his text Practical observations on conical cornea: and on the short sight, and other defects of vision connected with it in 1854.1 In 1859, British surgeon William Bowman described both the ophthalmoscopic features of keratoconus and its diagnosis and the first surgical attempts to restore vision by stretching the pupil into a stenopeic-like slit.2 In 1869, 

Swiss ophthalmologist Johan Horner used the term ‘keratoconus’ in his thesis on the treatment of the condition,3 which included attempts to reshape the cornea by chemical cauterisation. In 1888, in the first practical application of contact lens technology, French physician Eugène Kalt manufactured a glass scleral shell to improve vision in keratoconic eyes


Keratoconus


Area Tematica : cornea

Diagnosing Early Keratoconus

It had been speculated for many years that in keratoconus, the corneal epithelium responds to the thinning and ectasia of the cornea in a vivid way. We now know that corneal thinning prompts the epithelium to grow thinner as well. But in the area adjacent to the corneal thinning, the epithelium becomes thicker, as nature attempts to cover the irregularity and reduce the symptoms. High-frequency ultrasound has been able to show these phenomena for some time. Today, the Optovue Avanti Widefield OCT can show these activities quickly and easily via its Epithelial Thickness Mapping (ETM) software, which produces a color-coded map of the epithelial thickness across the central 6 mm of the cornea. 


Diagnosing Early Keratoconus


Area Tematica : cornea

Safety and efficacy of epithelium removal and transepithelial corneal collagen crosslinking for keratoconus


Safety and efficacy of epithelium removal and transepithelial corneal collagen crosslinking for keratoconus


Area Tematica : cornea

Anterior Segment Characteristics of Keratoconus Eyes Using ScheimpflugPlacido Topograph

Abstract 


Purpose: To assess anterior segment parameters of keratoconus (KC) eyes at different stages of the disease using Scheimpflug-placido topography (Sirius, CSO, Italy) in a sample of the southern Egyptian population. 

Methods: retrospective study of 400eyes of different grades of keratoconus along with 50 normal eyes as a control group were assessed for the following parameters: corneal thickness at apex (CCT), thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal volume (CV), corneal keratometry, corneal asphericity (Q), corneal elevation (both anterior and posterior) with aspherotoric surface as a reference, total root mean square (RMS), RMS Coma, RMS spherical aberration (SA), RMS Astigmatism, , Baiocchi Calossi Versaci front index (BCVf ) and BCV back index (BCVb ). They underwent Sirius Schemipflug placid topographer evaluation. 

Results: eyes were subdivided into: normal group (50 eyes), suspect KC (82eyes), grade 1 KC (80eyes), grade 2 KC (142eyes), and grade 3 KC (96eyes). The thinnest corneal thickness corneal thickness at apex and posterior corneal elevation were significantly different in all comparison groups. ACD values showed inconsistent differences between groups. Corneal volume was proved to be significant in comparing normal vs suspect KC group as well as in normal vs mild KC and normal vs moderate KC. Total RMS, RMS coma and BCV f and BCV b were significant for most groups 

Conclusion: Corneal thickness and high order aberrations proved to be able to diagnose different grades of keratoconus while corneal volume did not prove to have a significant role.


Anterior Segment Characteristics of Keratoconus Eyes Using ScheimpflugPlacido Topograph


Area Tematica : cornea

Validation of an Objective Scoring System for Forme Fruste Keratoconus Detection and Post-LASIK Ectasia Risk Assessment in Asian Eye

Purpose: To investigate the efficacy of the SCORE Analyzer (Bausch+Lomb TechnoLas, Germany) in detecting forme fruste keratoconus (FFKC) in Asian eyes and validate its usefulness as a risk assessment system for post–laser in situ keratomileusis (LASIK) keratectasia. 


Methods: We retrospectively evaluated corneal topographies with the Orbscan IIz system and independently tested them with the SCORE Analyzer through masked investigators. Eyes were classi- fied into 2 groups: (1) The FFKC group included clinically and topographically normal eyes with definite keratoconus in the contralateral eye. (2) The control group included normal preoperative topographies of patients with LASIK performed at least 4 years before with no resultant keratectasia. The main outcome measures were accuracy indicators: sensitivity, specificity, positive, and negative predictive values. Parameters in the calculation of the SCORE including irregularity at 3 mm, thinnest pachymetry, the difference between central and thinnest pachymetry (CP 2 TP), vertical decentration of the thinnest point, maximum posterior elevation, and anterior elevation of the thinnest point were compared in both groups. 

Results: We analyzed 128 Orbscans of 128 Asian patients. There were 24 FFKC eyes and 104 control eyes. SCORE was negative in 7 eyes (false negative) in the FFKC group and was positive in 2 eyes in the control group (false positive). The sensitivity was 70.8%, specificity 98.1%, positive predictive value 89.5%, and negative predictive value 93.6%. Irregularity at 3 mm, thinnest pachymetry, CP 2 TP, thinnest point decentration, maximum posterior elevation, and anterior elevation of the thinnest point were significantly different in both groups. 

Conclusions: The SCORE Analyzer algorithm, developed and validated in white eyes, was found to be valid and consistent in Asian eyes, showing good sensitivity and specificity in FFKC detection, and to be useful in objectively identifying cases at risk of post-LASIK keratectasia. 

Key Words: corneal topography, forme fruste keratoconus, postLASIK keratectasia (Cornea 2015;00:1–9)


Validation of an Objective Scoring System for Forme Fruste Keratoconus Detection and Post-LASIK Ectasia Risk Assessment in Asian Eye


Area Tematica : cornea

Strategies for improving the early diagnosis of keratoconus

Abstract: To diagnose keratoconus at its earliest stage is meaningful in order to avoid refractive surgery in the eye, which may lead to further damage in the abnormal cornea structure and consequently cause iatrogenic ectasia. 


In this article, the following aspects of detecting earliest stage of keratoconus were reviewed: 1) nomenclature of the earliest forms of keratoconus; 2) diagnosis of keratoconus using curvature-based topography (also known as Placido-based topography, ie, videokeratography) as a traditional method and elevationbased topography as a new method which has gained popularity in recent years; and 3) other methods analyzing keratoconus cornea like corneal biomechanics and wavefront sensing. 

Elevation-based topography using either Scheimpflug imaging techniques or slit-scanning imaging techniques has shown to be advantageous over the curvature-based topography in detecting keratoconus at its earliest stage. Posterior elevation of the cornea is notified to enhance the sensitivity and specificity of detection if used along with the measurements of anterior surface of the cornea.
 
Cornea biomechanics analysis and wavefront sensing also revealed differences between normal eyes and keratoconic eyes in their earliest stage. Combining the latest technology and the traditional techniques will be the future trend to improve early diagnosis of keratoconus.

Keywords: keratoconus, early diagnosis, Scheimpflug imaging, slit-scanning imaging, wavefront error, corneal biomechanics.


Strategies for improving the early diagnosis of keratoconus


Area Tematica : cornea

Epithelial, Stromal, and Total Corneal Thickness in Keratoconus: Three-Dimensional Display with Artemis Very-High Frequency Digital Ultrasound

ABSTRACT 


PURPOSE: To characterize the epithelial, stromal, and total corneal thickness profi le in a population of eyes with keratoconus. METHODS: Epithelial, stromal, and total corneal thickness profi les were measured in vivo by Artemis very high-frequency (VHF) digital ultrasound scanning (ArcScan, Morrison, Colo) across the central 6- to 10-mm diameter of the cornea on 54 keratoconic eyes. Maps of the average, standard deviation, minimum, maximum, and range of epithelial, stromal, and total corneal thickness were plotted. The average location of the thinnest epithelium, stroma, and total cornea were found. The cross-sectional semi-meridional stromal and total corneal thickness profi les were calculated using annular averaging. The absolute stromal and total corneal thickness progressions relative to the thinnest point were calculated using annular averaging as well as for 8 semi-meridians individually. 

RESULTS: The mean corneal vertex epithelial, stromal, and total corneal thicknesses were 45.75.9 µm, 426.438.5 µm, and 472.241.4 µm, respectively. The average epithelial thickness profi le showed an epithelial doughnut pattern characterized by localized central thinning surrounded by an annulus of thick epithelium. The thinnest epithelium, stroma, and total cornea were displaced on average by 0.480.66 mm temporally and 0.320.67 mm inferiorly, 0.310.45 mm temporally and 0.540.37 mm inferiorly, and 0.310.43 mm temporally and 0.500.35 mm inferiorly, respectively, with reference to the corneal vertex. The increase in semi-meridional absolute stromal and total corneal thickness progressions was greatest inferiorly and lowest temporally. 

CONCLUSIONS: Three-dimensional thickness mapping of the epithelial, stromal, and total corneal thickness profi les characterized thickness changes associated with keratoconus and may help in early diagnosis of keratoconus. [J Refract Surg. 2009;xx:xxx-xxx.] DOI:1.9999/1081597X-200905015-06


Epithelial, Stromal, and Total Corneal Thickness in Keratoconus: Three-Dimensional Display with Artemis Very-High Frequency Digital Ultrasound


Area Tematica : cornea

Orbscan 2 Corneal Imaging


Orbscan 2 Corneal Imaging


Area Tematica : cornea

Artemis epithelial thickness mapping helps to detect keratoconus

Stefanie Petrou 


Binder MD EPITHELIAL thickness mapping may enable LASIK to be performed in eyes that get excluded due to topographically suspect keratoconus.A majority of suspect keratoconic eyes by topography in a recent study were confirmed to be non-keratoconic by epithelial thickness mapping, and demonstrated equal stability and refractive outcomes as control eyes, at six to 12 months.


Artemis epithelial thickness mapping helps to detect keratoconus


Area Tematica : cornea

ArcScan Atemis 3


ArcScan Atemis 3


Area Tematica : cornea

1 parte Advanced diagnostic tecnologies in keratoconus andcorneal ectatic disease


1 parte Advanced diagnostic tecnologies in keratoconus andcorneal ectatic disease


Area Tematica : cornea

ARVO Abstracs Annual Meeting 2015


ARVO Abstracs Annual Meeting 2015


Area Tematica : cornea

Repeatability of corneal epithelial thickness measurements using Fourier-Domain Optical Coherence Tomography in normal and Post-LASIK eyes

Abstract Purpose

To evaluate the repeatability of corneal epithelial thickness (ET) and corneal thickness (CT) measurements in normal and LASIK eyes using the optical coherence tomography (OCT, RTVue).

Methods—In 35 right eyes of 35 normal subjects and 45 right eyes of 45 subjects with prior myopic LASIK, corneal ET and CT were evaluated in 17 areas: 1) one central zone within 0-2.0 mm diameter, 2) eight paracentral zones from 2.0-5.0 mm diameter, and 3) eight peripheral zones from 5.0-6.0 mm diameter. The repeatability was assessed using within-subject standard deviation (SD), coefficient of variation (CoV), and intraclass correlation coefficient (ICC).

 Results—At the central and paracentral zones, respectively, the SD values were 0.7 μm and 0.6-0.9 μm in normal eyes and 0.7 μm and 0.8-1.7 μm in LASIK eyes for ET, and 1.0 μm and 2.8-4.6 μm in normal eyes and 1.3 μm and 4.0-4.8 μm in LASIK eyes for CT. At the peripheral zones, in normal and LASIK eyes, respectively, SD values ranged from 0.8-1.2 μm and 1.4-2.2 μm for ET, and 4.1-6.4 μm and 6.0-9.1 μm for CT. The CoV values were low and ICC values were high in both groups for both ET and CT measurements.

Conclusion—The OCT produced excellent repeatability, especially at the central and paracentral zones up to 5-mm diameter for both corneal epithelial thickness and corneal thickness measurements.


Repeatability of corneal epithelial thickness measurements using Fourier-Domain Optical Coherence Tomography in normal and Post-LASIK eyes


Area Tematica : cornea

The Athens Protocol

P rogressive, asymmetrical corneal steepening associated with an increase in myopic and astigmatic refractive errors, combined with midperipheral and/or peripheral corneal thinning, represents a constellation of findings in ectatic corneal disorders (eg, keratoconus and pellucid marginal degeneration). 


These entitites are associated with asymmetry upon presentation, unpredictability of progression, and myriad abnormal topographic findings. Similar observations after LASIK surgery have been described as post-LASIK ectasia. 1-3 Analyses of series of eyes that have developed post-LASIK ectasia have suggested that certain preoperative and/or operative features may be associated with this adverse outcome of LASIK or PRK.4 

The fact that ectasia can occur in the absence of these features, or that it may not occur in spite of them, has confounded surgeons’ understanding of this complication.5 Nevertheless, post-LASIK ectasia is a visually disabling complication whose ultimate surgical treatment is penetrating keratoplasty when glasses or contact lenses can no longer provide patients with visual quality that allows them to perform their activities of daily living.

 During the past 10 years, the use of topical riboflavin combined with ultraviolet-A (UVA) irradiation to increase collagen cross-linking (CXL) has demonstrated the potential for retarding or eliminating the progression of keratoconus and post-LASIK ectasia. My colleagues and I have previously reported on the application of CXL in post-LASIK ectasia.6 We have found that once the progression has stabilized, it is possible to treat the surface of the eye with customized PRK to normalize the corneal surface by reducing irregular astigmatism. 

After using CXL for cases of ectasia, my colleagues and I introduced the Athens Protocol, which consists of same-day, topography-guided partial PRK and CXL.


The Athens Protocol


Area Tematica : cornea

The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay


The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay


Area Tematica : patologie maculari

The Diagnostic Accuracy of Optical Coherence Tomography Angiography for Neovascular Age-Related Macular Degeneration: A Comparison with Fundus Fluorescein Angiography


The Diagnostic Accuracy of Optical Coherence Tomography Angiography for Neovascular Age-Related Macular Degeneration: A Comparison with Fundus Fluorescein Angiography


Area Tematica : oct

μOCT imaging using depth of focus extension by self-imaging wavefront division in a commonpath fiber optic probe

Abstract: Optical coherence tomography (OCT) is an attractive medical modality due to its ability to acquire high-resolution, cross-sectional images inside the body using flexible, small-diameter, scanning fiber optic probes. Conventional, cross-sectional OCT imaging technologies have approximately 10-μm axial resolution and 30-μm lateral resolution, specifications that enable the visualization of microscopic architectural morphology. While this resolution is useful for many clinical applications, it is insufficient for resolving individual cells that characterize many diseases. To address this gap, a supercontinuum-laser-based, μm-resolution OCT (μOCT) system and a 500 μm-diameter, extended depth of focus single fiber optic probe for endoscopic and intravascular imaging were designed and fabricated. At the distal tip of the fiber optic probe, a cylindrical waveguide was used to divide the wavefront to provide multiple circular propagation modes. Once transmitted through a relatively high NA lens (NA >0.1), these modes were projected as multiple coaxial foci (~3 μm full width at half maximum (FWHM)) over a greatly extended focal depth range. The distal tip of the probe also contained a common-path reference reflectance to minimize polarization and dispersion imbalances between sample and reference arm light. Measurements showed that the probe provides a 20-fold depth of focus extension, maintaining a 3-5 µm lateral resolution (FWHM of PSF) and a 2 μm axial resolution over a depth range of approximately 1 mm. These results suggest that this new optical configuration will be useful for achieving high-resolution, cross-sectional OCT imaging in catheter/endoscope-based medical imaging devices. ©2016 Optical Society of 


America OCIS codes: (050.1220) Apertures; (070.7345) Wave propagation; (080.2740) Geometric optical design; (120.4640) Optical instruments; (170.2150) Endoscopic imaging; (170.4500) Optical coherence tomography. 


μOCT imaging using depth of focus extension by self-imaging wavefront division in a commonpath fiber optic probe


Area Tematica : oct

Corneal topography in keratoconus: state of the art

Abstract 

The morphological characterization of the cornea using corneal topographers is a widespread clinical practice that is essential for the diagnosis of keratoconus. 

The current state of this non-invasive exploratory technique has evolved with the possibility of achieving a great number of measuring points of both anterior and posterior corneal surfaces, which is possible due to the development of new and advanced measurement devices. All these data are later used to extract a series of topographic valuation indices that permit to offer the most exact and reliable clinical diagnosis. 

This paper describes the technologies in which current corneal topographers are based on, being possible to define the main morphological characteristics that the keratoconus pathology produces on corneal surface. Finally, the main valuation indices, which are provided by the corneal topographers and used for the diagnosis of keratoconus, are also defined.

 Keywords: Placido disc, Detection system, Topographer, Diagnosis


Corneal topography in keratoconus: state of the art


Area Tematica : cornea

Metodo Delphy

 Nel mondo antico l’oracolo di Delphi dispensava i suoi vaticini, ascoltato da chiunque si accingesse ad intraprendere azioni importanti o rischiose, in ogni caso impegnative. L’importanza di tali responsi era considerata tale da portare oltre che alla costruzione di un santuario, anche a far considerare Delphi come “l’ombelico del mondo”.


E' il metodo capostipite per la ricerca sociale partecipata. Si svolge attraverso l’interazione di un gruppo (panel) di individui (esperti, testimoni privilegiati, rappresentanti, cittadini) che interagiscono, argomentano attivamente un problema complesso creando così un processo di comunicazione di gruppo virtuoso.


Metodo Delphy


Area Tematica : cornea

Clinical assessment of a Novel multicolor-spot reflection Topographer with Scheimpflug Tomography and Placido Topography in Normal Eyes


Clinical assessment of a Novel multicolor-spot reflection Topographer with Scheimpflug Tomography and Placido Topography in Normal Eyes


Area Tematica : cornea
Ricerca Oculisti