What may be gained from standard photocoagulation during early worsening of diabetic retinopathy? An observational study in type-1 diabetic patients after tightening of glycaemic control.

OBJECTIVE: To assess the outcome of laser photocoagulation treatment for rapidly progressing diabetic retinopathy, socalled early worsening, subsequent to a rapid improvement of glycemic control. For the purpose of this study, early worsening was defined as any incidence or progression of retinopathy that followed a reduction in HbA1c by > 2% within 6 months.

MATERIAL AND METHODS: Retrospective observational study in type-1 diabetic patients in a university diabetes center.

PATIENTS: 23 patients with early worsening were identfied during a 16-year period, with a mean age of 25 years, duration of diabetes of 12 years, and glycated hemoglobin HbA1c of 12.4%; retinopathy was absent or mild nonproliferative at baseline. Focal, and/or panretinal laser coagulation was performed according to standard ETDRS criteria. Retinal pathology and visual acuity was followed-up for 12-120 months.

RESULTS: Improving metabolic control induced mild non-proliferative retinopathy without macular edema in 4 patients, which regressed without treatment. In 19 patients, symptomatic diabetic maculopathy developed with macular edema, resolving by focal coagulation in 3 patients. Of the remaining 16 patients, 14 developed proliferative retinopathy (7 of whom despite focal, grid or scatter coagulation pretreatment), and were treated by full panretinal coagulation. In 7 of the 14 patients with proliferative retinopathy, vitreous hemorrhages occurred requiring pars plana vitrectomy. Proteinuria, polyneuropathy, and impaired vision prior to laser treatment were indicative of poor prognosis. Visual acuity > 0.3 in at least one eye was preserved in 22 of the 23 patients.

CONCLUSIONS: In patients with type-1 diabetes mellitus and early worsening of diabetic retinopathy, the benefit of standard laser photocoagulation was limited, and particularly in the presence of symptomatic macular edema.