Estimating the delay between onset and diagnosis of type 2 diabetes from the time course of retinopathy prevalence.

OBJECTIVE: By correlating known diabetes duration with the prevalence of retinopathy, more than 10 years have been estimated to lapse between the onset and diagnosis of type 2 diabetes. Such calculations, however, assumed a linear model, included stages of retinopathy not specific to diabetes, and allowed 5 years for retinopathy to occur after the onset of diabetes. We calculated the duration of undiagnosed type 2 diabetes in outpatients screened for retinopathy in a hospital-based diabetes clinic after correcting these assumptions. RESEARCH DESIGN AND METHODS: Diabetic patients (n = 12,074; 35,545 fundus examinations) were stratified into younger onset (YO; age at onset <30 years) or older onset (OO; age at onset ≥30 years), insulin treated (IT) or not IT (NIT), and with mild/more severe diabetic retinopathy (AnyDR) or moderate/more severe diabetic retinopathy (ModDR). The best-fitting equation correlating known duration among the OO-NIT group with the prevalence of ModDR was used to extrapolate time from appearance of retinopathy to diagnosis of type 2 diabetes. Time for retinopathy to develop after diabetes was calculated from the equation correlating the duration among the YO-IT group with appearance of ModDR. RESULTS: There were 1,719 patients in the OO-NIT group with AnyDR and 685 with ModDR and 756 in the YO-IT group with AnyDR and 385 with ModDR. A linear model showed ModDR appeared 2.66 years before diagnosis among those in the OO-NIT group. A quadratic model suggested that ModDR appeared 3.29 years after diagnosis among those in the YO-IT group. The resulting estimate was 6.05 years (2.66 + 3.29) between the onset and diagnosis of diabetes, compared with 13.36 years using standard criteria. CONCLUSIONS: Using best-fitting models and stratifying by glucose-lowering treatment and severity of retinopathy substantially lowers the estimated duration of undiagnosed type 2 diabetes.

Photodynamic therapy for chronic central serous chorioretinopathy.

PURPOSE: To determine whether photodynamic therapy (PDT) is effective for treatment of chronic central serous chorioretinopathy (CSC). METHODS: Sixteen eyes with chronic CSC and macular detachment documented by optical coherence tomography (OCT) received PDT guided by indocyanine green (ICG) angiography according to the parameters outlined in the TAP Study. One or more laser spots were applied to the areas of choroidal vascular hyperpermeability that corresponded to retinal pigment epithelium decompensation. Patients were observed for 6 to 12 months. Two PDT sessions 1 month apart were performed on 2 eyes. Examinations included visual acuity measurement, fundus biomicroscopy, fluorescein and ICG angiography, and OCT. RESULTS: Macular exudation resolved completely in 13 eyes (81%) and partially regressed in 3. Choriocapillaris hypoperfusion was shown by ICG angiography for several months at the site of PDT application. Visual acuity improved 1 to 4 lines in 11 eyes and was unchanged in 5 eyes. CONCLUSIONS: ICG-guided PDT performed according to the parameters outlined by the TAP Study seems effective for treating chronic CSC. Further studies are needed to verify treatment safety and the time and rate of recurrences.