Observational Study of DME Following Scatter Laser Photocoagulation

Diabetic Macular Edema

DME, Laser, macular edema, retinopathy, scatter photocoagulation

The development or worsening of macular edema following full scatter photocoagulation is a well recognized occurrence. However, there is limited literature in this regard. The purpose of this study is to determine the incidence and extent of macular edema following scatter laser photocoagulation surgery using optical coherence tomography (OCT) in eyes without macular edema prior to scatter laser photocoagulation and to explore whether the incidence and extent of macular edema varies according to the number of sittings included in the treatment regimen. Study eyes will receive one of two types of scatter photocoagulation with results compared through use of OCT and photography images, as well as visual acuity testing.

Study eyes will receive scatter photocoagulation given by one of the following two regimens. To reduce selection bias, investigators will be required, prior to study initiation, to indicate which treatment (1 PRP sitting or 4 PRP sittings) they will administer. Only the selected treatment will be performed by a given investigator on study eyes. * 1 sitting with a minimum of 1200 to a maximum of 1600 burns, with one burn width separation of burns and scatter extending from the peripheral arcades to beyond the equator. * 4 sittings, each separated by four weeks (+4 days), with approximately 300 burns in each of the first two sittings and investigator judgment for number of burns for the third and fourth sittings as long as the total for the four sittings is between 1200 and 1600 burns. Both of these regimens conform with usual clinical practice. The study aims to enroll 150 eyes. At least 40 eyes will be enrolled with prior focal laser photocoagulation and at least 40 eyes without prior focal laser treatment. After enrollment of 80 eyes (40 with prior treatment and 40 without prior treatment), an interim analysis will be conducted so that focused enrollment strategies can be implemented if the analysis suggests that more subjects in a subgroup should be entered. Approximately half of the eyes will receive each scatter treatment regimen. The following procedures will be done on the study eye at baseline and at each scheduled visit (except 8 and 12 weeks at which exam data are not collected) unless otherwise specified: * OCT * E-ETDRS visual acuity in both eyes (refraction in the study eye at baseline, 17 weeks, and 34 weeks) * Fundus photographs (7-fields at baseline and 3-fields at 34 weeks only) * Photographs to document the scatter photocoagulation (day of the first PRP sitting only)