PDF in Oftalmologia in italiano/inglese (articoli presenti: 941)

A review of optical coherence tomography angiography (OCTA)


A review of optical coherence tomography angiography (OCTA)


Area Tematica : oct

Mapping the 3D Connectivity of the Rat Inner Retinal Vascular Network Using OCT Angiography


Mapping the 3D Connectivity of the Rat Inner Retinal Vascular Network Using OCT Angiography


Area Tematica : oct

Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography


Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography


Area Tematica : oct

Texture Analysis Methods for Medical Image Characterisation


Texture Analysis Methods for Medical Image Characterisation


Area Tematica : oct

Quantification of Vessel Density in Retinal Optical Coherence Tomography Angiography Images Using Local Fractal Dimension


Quantification of Vessel Density in Retinal Optical Coherence Tomography Angiography Images Using Local Fractal Dimension


Area Tematica : oct

Fractal Dimension Estimation Methods for Biomedical Image


Fractal Dimension Estimation Methods for Biomedical Image


Area Tematica : oct

Wide-field optical coherence tomography based microangiography for retinal imaging


Wide-field optical coherence tomography based microangiography for retinal imaging


Area Tematica : oct

3-2-1 Action ... Live from Atlanta


3-2-1 Action ... Live from Atlanta


Area Tematica : difetti di vista

Innovative IOL technologies for the cataract surgeon


Innovative IOL technologies for the cataract surgeon


Area Tematica : cataratta

Achieving excellent visual outcomes from cataract surgery


Achieving excellent visual outcomes from cataract surgery


Area Tematica : cataratta

Today’s options and opportunities: What is the “new bar” for presbyopia correction?


Today’s options and opportunities: What is the “new bar” for presbyopia correction?


Area Tematica : difetti di vista

Laser-assisted cataract surgery at 30,000 feet: Examining clinical aspects as seen in the literature


Laser-assisted cataract surgery at 30,000 feet: Examining clinical aspects as seen in the literature


Area Tematica : cataratta

Comparison of amplitude-decorrelation, specklevariance and phase-variance OCT angiography methods for imaging the human retina and choroid


Comparison of amplitude-decorrelation, specklevariance and phase-variance OCT angiography methods for imaging the human retina and choroid


Area Tematica : oct

Optical coherence tomography (OCT) angiography findings in retinal arterial macroaneurysms


Optical coherence tomography (OCT) angiography findings in retinal arterial macroaneurysms


Area Tematica : oct

Clinical applications of spectral domain optical coherence tomography in retinal diseases


Clinical applications of spectral domain optical coherence tomography in retinal diseases


Area Tematica : oct

Methods and algorithms for optical coherence tomography-based angiography: a review and comparison


Methods and algorithms for optical coherence tomography-based angiography: a review and comparison


Area Tematica : oct

Swept-Source OCT Angiography: SS OCT AngioTM


Swept-Source OCT Angiography: SS OCT AngioTM


Area Tematica : oct

Comparison of amplitude-decorrelation, specklevariance and phase-variance OCT angiography methods for imaging the human retina and choroid

Abstract: We compared the performance of three OCT angiography (OCTA) methods: speckle variance, amplitude decorrelation and phase variance for imaging of the human retina and choroid. Two averaging methods, split spectrum and volume averaging, were compared to assess the quality of the OCTA vascular images. All data were acquired using a swept-source OCT system at 1040 nm central wavelength, operating at 100,000 A-scans/s. We performed a quantitative comparison using a contrast-to-noise (CNR) metric to assess the capability of the three methods to visualize the choriocapillaris layer.


For evaluation of the static tissue noise suppression in OCTA images we proposed to calculate CNR between the photoreceptor/RPE complex and the choriocapillaris layer. Finally, we demonstrated that implementation of intensity-based OCT imaging and OCT angiography methods allows for visualization of retinal and choroidal vascular layers known from anatomic studies in retinal preparations. OCT projection imaging of data flattened to selected retinal layers was implemented to visualize retinal and choroidal vasculature. User guided vessel tracing was applied to segment the retinal vasculature. The results were visualized in a form of a skeletonized 3D model


Comparison of amplitude-decorrelation, specklevariance and phase-variance OCT angiography methods for imaging the human retina and choroid


Area Tematica : oct

Optical Coherence Tomography Angiography in Retinal Vascular Diseases and Choroidal Neovascularization


Optical Coherence Tomography Angiography in Retinal Vascular Diseases and Choroidal Neovascularization


Area Tematica : oct

OECD Health Statistics 2014


OECD Health Statistics 2014


Area Tematica : medicina

10 Punti sul Futuro della Sanità Pubblica in Europa


10 Punti sul Futuro della Sanità Pubblica in Europa


Area Tematica : medicina

SOOFT


SOOFT


Area Tematica : cataratta

Visufarma


Visufarma


Area Tematica : cataratta

Polioftalmica


Polioftalmica


Area Tematica : cataratta

Meccanottica Mazza


Meccanottica Mazza


Area Tematica : cataratta

Frastema


Frastema


Area Tematica : cataratta

ACIDO IALURONICO ALLO 0,2% COME TERAPIA PROTETTIVA DEGLI EFFETTI COLLATERALI DELLA TERAPIA TOPICA ANTIGLAUCOM


ACIDO IALURONICO ALLO 0,2% COME TERAPIA PROTETTIVA DEGLI EFFETTI COLLATERALI DELLA TERAPIA TOPICA ANTIGLAUCOM


Area Tematica : glaucoma

Relationship between Functional and Structural Changes in Diabetic Vessels in Optical Coherence Tomography Angiography

The decorrelation signals in optical coherence tomography angiography (OCTA) are derived from the flow of erythrocytes and concomitantly delineate the retinal vasculature. We compared the structural and functional characteristics of vascular lesions visualized in fluorescein angiography (FA), OCTA, and en-face OCT images in 53 eyes (28 patients) with diabetic retinopathy (DR). 

The foveal avascular zone (FAZ) areas in OCTA images in the superficial layer almost corresponded to those in FA images. The FAZ areas in the en-face OCT images in the superficial layer were smaller than those in the FA images and correlated with each other, which agreed with the finding that en-face OCT images often delineated the vascular structure in the nonperfused areas in FA images. Microaneurysms appeared as fusiform, saccular, or coiled capillaries in OCTA images and ringed, round, or oval hyperreflective lesions in en-face OCT images. 

OCTA and en-face OCT images detected 41.0 ± 16.1% and 40.1 ± 18.6%, respectively, of microaneurysms in FA images, although both depicted only 13.9 ± 16.4%. The number of microaneurysms in FA images was correlated with that in OCTA and en-face OCT images. Comparisons of these modalities showed the associations and dissociations between blood flow and vascular structures, which improves the understanding of the pathogenesis of DR.


Relationship between Functional and Structural Changes in Diabetic Vessels in Optical Coherence Tomography Angiography


Area Tematica : oct

Pattern of Retinal Nerve Fiber Layer Thickness Loss in Fetal Alcohol Syndrome: A Spectral-Domain Optical Coherence Tomography Analysis

Introduction: Optic disc hypoplasia is a common feature in fetal alcohol syndrome. Thus, we aimed to evaluate the optic disc morphology changes and the peripapillary retinal nerve fiber layer thickness in these patients. 


Material and Methods: We performed spectral-domain optical coherence tomography in a cohort of 11 patients (22 eyes) with fetal alcohol syndrome and in an age-matched control group. We evaluated optic nerve head parameters (optic disc area and diameter, rim area, cup/disc horizontal and vertical ratios) and peripapillary retinal nerve fiber layer thickness.

Results: Mean optic disc area, rim area and optic disc diameter were, respectively, in fetal alcohol syndrome patients and control subjects: 1.540 ± 0.268 and 1.748 ± 0.326 mm2 ; 1.205 ± 0.286 and 1.461 ± 0.314 mm2 ; 1.417 ± 0.124 and 1.501 ± 0.148 mm (p < 0.05). We found no significant differences between groups for cup/disc ratios. Mean retinal nerve fiber layer thickness was significantly lower in fetal alcohol syndrome patients (90.500 ± 9.344 µm) as compared to controls (111.000 ± 7.855 µm) (p < 0.0001). Analysis showed a significant decrease in retinal nerve fiber layer thickness for the superior, inferior and nasal quadrants (p < 0.005). The temporal quadrant showed no significant differences. 

Discussion: Optic disc area, rim area and optic disc diameters were significantly reduced in fetal alcohol syndrome patients. Although mean peripapillary retinal nerve fiber layer thickness was decreased, the temporal quadrant was spared. 

Conclusion: In addition to a smaller optic disc area/ diameter and rim area, we found a heterogeneous peripapillary retinal nerve fiber layer thickness loss in fetal alcohol syndrome patients with sparing of the temporal quadrant. Spectral-domain optical coherence tomography may be useful to determine the presence of fetal alcohol syndrome status.

Keywords: Fetal Alcohol Spectrum Disorders; Optic Nerve Diseases; Nerve Fibers; Retina.


Pattern of Retinal Nerve Fiber Layer Thickness Loss in Fetal Alcohol Syndrome: A Spectral-Domain Optical Coherence Tomography Analysis


Area Tematica : oct

PITFALLS IN OPTICAL COHERENCE TOMOGRAPHY IMAGIN


PITFALLS IN OPTICAL COHERENCE TOMOGRAPHY IMAGIN


Area Tematica : oct

Findings of Optical Coherence Tomography of Retinal Nerve Fiber Layer in Two Common Types of Multiple Sclerosis

Abstract

Multiple sclerosis (MS) is the most prevalent disease caused by the inflammatory demyelinating process that causes progressive nervous system degeneration over the time. Optical Coherence Tomography (OCT) is a non-invasive optical imaging technology, which can measure the thickness of retinal nerve fiber layer as well as the diameter of the macula. The purpose of the study is evaluation OCT findings in two common types of multiple sclerosis.

For doing the cross-sectional study, 63 patients with two prevalent types of multiple sclerosis (35 patients with Relapse Remitting Multiple Sclerosis (RRMS) and 28 patients with Secondary Progressive Multiple Sclerosis (SPMS) were evaluated for 6 months. Exclusion criteria of the study were a history of optic neuritis, suffering from diabetes mellitus, hypertension, ocular disease, and the presence of other neurologic degenerative diseases.

Then, the thickness of retinal nerve fiber layer (RNFL), as well as thickness and volume of the macula, were measured in the patients using OCT technology. The disability rate of patients was evaluated according to Expanded Disability Status Scale (EDSS). Finally, data was analyzed by means of SPSS software.

Overall, 35 patients with RRMS (with mean age of 32.37+10.01, average disease period of 3.81+3.42 and mean EDSS of 1.84+0.45) and 28 patients with SPMS (with mean age of 39.21+9.33, average disease period of 11.32+5.87 and mean EDSS of 5.12+1.46) were assessed and compared in terms of retinal nerve fiber layer and size and thickness of macula. In all of these sections, the thicknesses were smaller in SPMS patients than patients with RRMS. 

But, there was a significant difference in total thickness (81.82µm versus 96.03µm with P=0.04) and thickness of temporal sector (54.5 µm versus 69.34 µm with P=0.04) of retinal nerve fiber layer and macular size at the superior sector of external ring (1.48 mm³ versus 1.58 mm³ with P=0.03), and nasal sector of external ring surrounding macula (1.53 mm³ versus 1.66 mm³ with P=0.03).

No significant correlation was found among rising disability and reduced thickness of macula and optic nervous layer. Based on the study results, it can be said that OCT is a useful method for showing axonal degeneration severity and evaluation of various drugs effects on the course of MS disease, and thus we can change drugs based on OCT findings for achieving best results.


Findings of Optical Coherence Tomography of Retinal Nerve Fiber Layer in Two Common Types of Multiple Sclerosis


Area Tematica : oct

Is Spectral-Domain Optical Coherence Tomography Always Able to Detect the Anti-Vascular Endothelial Growth Factor Action on Neovascular Membrane?

Keywords Spectral-domain optical coherence tomography · Age-related macular degeneration · Intravitreal injection 

Abstract Purpose: To show the presence of an active neovascular membrane in age-related macular degeneration even if optical coherence tomography (OCT) does not detect intra- or subretinal edema. 

Methods: This is a retrospective case report. During the follow-up after the intravitreal injection, 3 patients showed no intraretinal or subretinal edema by OCT; however, there was a progressive reduction in their visual acuity; thus, a fluorangiography (FA) examination was performed. 

Results: In these 3 cases, FA showed an active neovascular network.

Conclusion: OCT could show a real reduction in the edema, but it is not always able to detect neovessel presence. Intravitreal injection could improve the vessel permeability without care and delete the neovascular network.


Is Spectral-Domain Optical Coherence Tomography Always Able to Detect the Anti-Vascular Endothelial Growth Factor Action on Neovascular Membrane?


Area Tematica : oct

Automated macular choroidal thickness measurement by swept‑source optical coherence tomography in pseudoxanthoma elasticum

Abstract Introduction: Pseudoxanthoma elasticum (PXE) typically involves elastic fibers in blood vessels and Bruch mem‑ brane. Our purpose was to analyze retinal and choroidal macular thickness in patients with angioid streaks due PXE compared with a control group.


Methods: Best‑corrected visual acuity (BCVA), axial length (AL), and macular swept‑source optical coherence tomog‑ raphy were obtained. Automated segmentations of the retina and the choroid were used to obtain the corresponding thickness values. An age, gender and AL matched control group was used to compare the thickness values. 

Results: Twelve eyes of 6 patients were included. The mean BCVA was 0.68 ± 0.29 versus 1.0 in controls (p < 0.001). The mean macular retinal thickness was thinner in eyes with PXE (p = 0.038). Only patients with choroidal neovascu‑ larization (NV) showed statistically significant differences in the mean macular choroidal thickness (p = 0.008). 

Conclusions: The present study shows that choroidal thickness may be thinner in eyes with NV due to angioid streaks in PXE compared with healthy eyes analyzed by an automated segmentation of the choroid. Further studies are warranted in order to assess the importance of this choroidal changes in the pathogenesis of retinal disturbances related to PXE and its influence in long‑term follow‑up. 

Keywords: Automated segmentation, Choroid, Neovascularization, PXE


Automated macular choroidal thickness measurement by swept‑source optical coherence tomography in pseudoxanthoma elasticum


Area Tematica : oct

Optical coherence tomography in the evaluation of structural changes in primary open-angle glaucoma with and without elevated intraocular pressure


Optical coherence tomography in the evaluation of structural changes in primary open-angle glaucoma with and without elevated intraocular pressure


Area Tematica : oct

Detecting early keratoconus and avoiding iatrogenc ectasia: the score analyzer

LASIK is a wonderful technique that has enabled millions of people to enjoy spectacle independence and improved UCVA over the past 20 years. 


Post-LASIK ectasia is a rare (estimated prevalence, less than 1 in 2,000) but potentially sight-threatening complication. The main risk factor for post-LASIK ectasia is the presence of undetected early forms of subclinical keratoconus.

Therefore, improving the sensitivity and specificity of automated techniques for preoperative screening with corneal topography is a valuable goal in refractive surgery.

Initially, Placido-disc–based detection indices derived from specular anterior corneal topography were judged the most sensitive and specific to detect the earliest forms of subclinical keratoconus.


•   The main risk factor for post-LASIK ectasia is the presence of undetected early forms of subclinical keratoconus; therefore, improving the sensitivity and specificity of automated techniques for preoperative screening with corneal topography is a valuable goal in refractive surgery.

 •  The concept of the SCORE Analyzer originated from the authors’ aim to provide clinicians with a unique number to rate the ectasia susceptibility of myopic eyes by using linear discriminant analysis.

 •  Study results confirmed that the combination of Placido, elevation, and tomography data is a more sensitive and specific detector of early subclinical keratoconus than either Placido-disc topography or elevation data alone. 


Detecting early keratoconus and avoiding iatrogenc ectasia: the score analyzer


Area Tematica : cornea

Keratoconus Expert Meeting, 2014 London


Keratoconus Expert Meeting, 2014 London


Area Tematica : cornea

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.


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


Area Tematica : cornea

Associations of Biomechanical Properties of the Cornea With Environmental and Metabolic Factors in an Elderly Population: The ALIENOR Study

PURPOSE. The purpose of this study was to assess the associations of biomechanical properties of the cornea with metabolic and environmental factors in an elderly population.


METHODS. The ALIENOR (Antioxydants, Lipides Essentiels, Nutrition, and Maladies OculaiRes) study is a population-based study. In 2009–2010, 624 subjects, aged 74 years or more, underwent an eye examination, including intraocular pressure (IOP), central corneal thickness (CCT), and biomechanical properties of the cornea measurements using the Ocular Response Analyzer. Socio-demographic, lifestyle, and medical history data were collected using standardized questionnaires. Mean lifetime ambient ultraviolet (UV) exposure was estimated using residential history and statistics of UV radiation at each location using the Eurosun UV database.

RESULTS. Mean age was 82.2 6 4.3 years. Mean corneal hysteresis (CH), corneal resistance factor (CRF), and CCT were 9.4 6 1.9, 9.8 6 1.9 mm Hg, and 551.6 6 36.8 lm, respectively. In the multivariate analysis, CH and CRF values were significantly lower in subjects older than 80 years (0.56; 95% confidence interval [CI]:0.89;0.24); P < 0.001 and 0.48; 95% CI: 0.75;0.20; P < 0.001, respectively), in subjects having higher ambient UV exposure (0.50; 95% CI: 0.88;0.12; P < 0.01; and 0.46; 95% CI: 0.78; 0.13); P < 0.05, respectively), and in subjects with high plasma LDL cholesterol (CH: 0.46; 95% CI: 0.86;0.03; P < 0.05; and CRF: 0.37; 95% CI: 0.72;0.008; P < 0.05). Central corneal thickness was significantly higher in former smokers than in never smokers (þ11.01; 95% CI: 0.48;21.55; P < 0.05) and was not significantly associated with age, ambient UV exposure, diabetes, or LDL cholesterol.

CONCLUSIONS. Biomechanical properties of the cornea are modified by metabolic and lifetime environmental factors, especially UVexposure. The manner these factors may influence onset and progression of ocular diseases or IOP measurements need further investigation. Keywords: biomechanics, corneal elasticity, corneal hysteresis, corneal biomechanical properties, aging, UV exposure.


Associations of Biomechanical Properties of the Cornea With Environmental and Metabolic Factors in an Elderly Population: The ALIENOR Study


Area Tematica : cornea

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
Ricerca Oculisti

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