Keratoconus (KC) is the most common cornea ectatic disorder. It is characterized by a cone-shaped thin cornea leading to myopia, irregular astigmatism, and vision impairment. It affects all ethnic groups and both genders. Both environmental and genetic factors may contribute to its pathogenesis. This review is to summarize the current research development in KC epidemiology and genetic etiology. Environmental factors include but are not limited to eye rubbing, atopy, sun exposure, and geography. Genetic discoveries have been reviewed with evidence from family-based linkage analysis and fine mapping in linkage region, genome-wide association studies, and candidate genes analyses. A number of genes have been discovered at a relatively rapid pace. The detailed molecular mechanism underlying KC pathogenesis will significantly advance our understanding of KC and promote the development of potential therapies.

The prevalence of keratoconus in Jerusalem was found to be much higher than that seen in other parts of the world, except India. This may be related to a combination of genetic and environmental factors. Positive family history, male gender and atopy were shown to be significant predictors. The results of this study signal a need for public health outreach and intervention for keratoconus.

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Background: Undercorrection has recently been found to enhance the rate of progression of myopia. This result was thought to be controversial as it contrasted with expectations based on animal studies, as well as the results found wearing progressive addition lenses. The aim of the present study was to again determine the effect of undercorrection on the progression of myopia in a random population of children who are known to be very susceptible to myopia. Methods: A cohort of 48 myopic children, aged six to15 years was randomly assigned to either a fully corrected group (n = 23) or to an undercorrected group (n = 25). The subjects in the latter group were blurred by +0.50 D. The prospective study extended over a period of 18 months. Optometric examinations were carried out at the beginning of the study, then at six-month, 12-month and 18-month follow-up. Results: Undercorrection produced a slight but not statistically significant increase in myopic progression over the 18-month period equal to 0.17 D, compared to full correction. A similar trend towards an increase in progression was noted in females and in children with near esophoria. Conclusion: This study supports the evidence that undercorrection does not represent an effective therapy to slow the rate of early-onset myopic progression, regardless of near heterophoria.

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