Articoli Scientifici di Oftalmologia
Argomento : 2
Parameters to Document Progression of Keratoconus
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The Keratoconus Expert Group, conceived and established by Jérôme C. Vryghem, MD, is a vibrant group of invited
international corneal experts with special interest in keratoconus. Prior to the meeting of the European Society of
Cataract and Refractive Surgeons (ESCRS) in October 2013, the group, in its fourth year, convened with a specific purpose
to arrive at a consensus in three principal areas:
(1) the criteria used to determine the progression of keratoconus,
(2) when (and how) to perform corneal collagen crosslinking,
and (3) the value of intrastromal corneal ring segments.
I had the privilege and rather challenging job of chairing the section on establishing criteria for measuring the progression
of keratoconus. I say challenging because, as you will see from the articles in this bonus feature—particularly those by A. John
Kanellopoulos, MD, and Michael Belin, MD—there are considerable differences in opinion on this subject.
Although there is general agreement about what should be considered progression, it is clear that more scientific study is
required when it comes to measuring subtle progression. There are a number of variables at play, and each one is unique, with
its own characteristics. Even data analysis using averages is fraught with problems, unless one has the luxury of access to 100%
data in all eyes at all timeframes with similar criteria, including cessation of contact lens wear prior to evaluation. As Dr. Belin
points out, most patients with keratoconus are dependent on hard contact lenses, and, as these lenses definitely affect anterior
corneal shape, basing decisions mainly on anterior parameters carries risk of potential error.
Requesting that patients with
keratoconus keep their lenses out for 1 month in order to evaluate them properly is idealistic and probably overkill.
Often, when there is considerable controversy, simple approaches are best. Dr. Belin’s approach is quite attractive: Corneal
thickness and posterior elevation may be the best criteria to use, perhaps with the addition of corneal volumetric change. We
may also need an alternative approach altogether, using a different method of diagrammatic presentation; Damien Gatinel,
MD, has used a clever method in his Score software (Bausch + Lomb Technolas), which employs multiple variables to evaluate
the risk of keratoconus in corneas prior to elective ablative refractive surgery.
Getting back to basics, evaluating markers for keratconus is likely the ultimate tool, and Jesús Merayo, MD, PhD, reports
on some of his work in this area, which looks interesting and promising. We hope you enjoy these articles, and we expect
that you have your own individual opinions. Please do not hesitate to contact us—we would love to have the opportunity
to publish your views.
