To report on our initial experience screening for diabetic retinopathy (DR) using digital fundus photography and standarized criteria. Cross-sectional prospective study of all 1327 diabetic patients referred to the Ophthalmology Department of the Clorito Picado Clinic in San José, Costa Rica between April 2008 and March 2009. Patients were screened with a single-field 45-degree digital color retinal image centered on the fovea. The main outcome measures were prevalence of DR, waiting time for a fundus photograph appointment and the number of patients that needed to be evaluated by an ophthalmologist. In this population of 1327 patients, 85% did not have any retinopathy. The prevalence of DR was 15%. Mild non-proliferative DR (NPDR) was seen in 5.8% (70/1215), moderate NPDR in 3.9% (47/1215), severe NPDR in 4.7% (57/1215) and proliferative DR in 0.6% (8/1215). Macular edema was present in 2.6% (32) patients. 13.8% of patients required pupillary dilation for an adequate image to be taken and 8.8% of the images were unreadable. The average waiting time for a fundus photograph appointment was 49.1 days. A total of 13.8% (183/1327) patients were referred to the ophthalmologist. Of these referrals, 61.2% (112/183) were because of unreadable images and 38.8% (71/183) were referred for further ophthalmic treatment. Digital fundus photographic screening for DR appears to be a viable option for the improvement of screening for DR in Costa Rica.

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Background: Leber Congenital Amaurosis (LCA) and Early Onset Retinal Dystrophy (EORD), are primary causes of inherited childhood blindness. Both are autosomal recessive diseases, with more than 25 genes explaining approximately ~70% of cases. However, the genetic cause for many cases remains unclear. Sequencing studies from genetically isolated populations with increased prevalence of a disorder has proven useful for rare variant studies, making Costa Rica an ideal place to study LCA/EORD genetics. Materials and Methods: Twenty-eight affected children (25 LCA, three EORD) and their immediate family members, totaling 52 individuals (30 affected) from 22 families, were sequenced. Whole exome sequencing was performed on all affected individuals. Available parents were analyzed either by WES or Sanger sequencing to determine transmission. Results: All affected individuals demonstrated compound heterozygous or homozygous mutations in known Inherited Retinal Disease (IRD) genes. Twelve variants were identified in at least one individual in three genes, RDH12, RPE65, and USH2A. Four recurrent RPE65 mutations were observed in 97% of individuals and 95% of families. All patients with LCA and two of the three individuals with EORD had biallelic mutations in RPE65; one child with EORD had a homozygous RDH12 mutation. Conclusions: These data suggest that the majority of LCA/EORD in Costa Rica is due to four founder effects in RPE65 which have been maintained in this genetically isolated population. This finding is of great clinical significance due to the availability of gene therapy recently approved in US and European Union for patients with biallelic RPE65 deficits.

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