JAN 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/104833

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January 2013 a type 2 bubble, on the other hand, immediately deflates it; what's more, after peeling, the surgeon can create a type 1 bubble in the remaining tissue. Through subsequent histologic examination, Prof. Dua identified five to eight compact lamellae of type 1 collagen immediately anterior to the Descemet's membrane, posterior to the last row of keratocytes. This pre-Descemetic "Dua's Layer" has several implications, including: a DL-DMEK is likely to be easier to handle and unfold than DMEK; the layer may have a role to play in acute hydrops of keratoconus and in pre-Descemet's dystrophy; it may influence corneal curvature and biomechanics. Editors' note: Prof. Dua has no financial interests related to his lecture. Keratoconus in the dark While much work, even progress, has been made in the diagnosis and management of keratoconus, the pathogenesis of the condition remains poorly understood, said Gerard Sutton, M.D., Sydney. The histopathologic pattern is clear: central, paracentral thinning with breaks in Bowman's capsule and decreased keratocyte density, but is this the result of defective formation or tissue loss or a combination of the two? Epidemiology provides some clues—the condition is very common in India, suggesting a genetic basis—while also seeming to contradict them—this prevalence is not seen among Indians living in the U.K., suggesting environmental determinants. Although genes and systemic conditions have been associated with keratoconus, the data, said Dr. Sutton, suggests sporadic or incomplete penetrance. Keratoconus appears to be the end stage of multiple disease entities with different pathogenesis, resulting from a cascade that begins with a genetic predisposition, followed by an environmental factor or some other indeterminate "second hit," leading to epithelial cell abnormali- ties that in turn cause alterations in signaling stimulating apoptosis. This suggests the potential for a single pathway on which it may be possible to target therapy: the "wnt" pathway. Fortunately, despite the obscurity of its pathogenesis, there is a wide range of options for managing the condition. Penny Asbell, M.D., New York, described some useful tools surgeons may not be aware of, or might not utilize enough if they do: contact lenses. Dr. Asbell described three new kinds of contact lens designed for keratoconus: hybrid lenses combining a rigid gas-permeable lens with a soft skirt; soft contact lenses specially designed to vault over the keratoconus; and scleral contact lenses, also designed to vault over the cornea. EW MEETING REPORTER 61 Patients need to be trained to use these lenses properly, but they are valuable tools for keratoconus patients in whom surgery may not be the immediate preferred option. EW Editors' note: Drs. Asbell and Sutton spoke at a symposium on keratoconus sponsored by the American Academy of Ophthalmology. They have no financial interests related to their lectures.

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