Purchase this article with an account.
Jan Lammer, Matthias Bolz, Christoph Mitsch, Christoph D. Scholda, Ursula Schmidt-Erfurth, DRRG (Diabetic Retinopathy Research Group); Comparison Of 532nm And 577nm Photocoagulation Of Microaneurysms In Focal Diabetic Macular Edema Using Fluorescence Angiography, Polarization Sensitive And Spectral Domain Oct (3 Month Follow-up). Invest. Ophthalmol. Vis. Sci. 2012;53(14):385.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare in-vivo changes in ultrastructural morphology of microaneurysms (MA) and underlying retinal pigment epithelium (RPE) after retinal photocoagulation using two different wave lengths (532nm and 577nm).
15 patients (15 eyes) underwent focal photocoagulation due to diabetic maculopathy. Patients were randomized into two groups: in group 1 photocoagulation was performed using a 577nm ("yellow") wavelength and in group 2 a 532nm ("green") wavelength was used (both Quantel Medical). At baseline, day one, week one and in monthly intervals until month three, the characteristic retinal morphology and localization of effects due to the laser tissue interaction were imaged. Follow-up examinations included best corrected visual acuity (BCVA) testing, slit lamp and fundus examination, spectral domain optical coherence tomography (SD-OCT), polarization sensitive OCT (PS-OCT) and autofluorescence. Fluorescence angiography was performed at baseline and at month 3. PS-OCT, currently being in a prototype state, was used to specifically detect the RPE-changes due to its certain polarization scrambling qualities.
After one day, in both groups, the photocoagulation effects were sharply delineated from the surrounding unaffected retina while RPE changes were subtle. The morphology of MA was changed from ring-like, hollow structure at baseline to a more solid, hyperreflective appearance, which was seen more often in group 1 than in group 2. Week 1 follow-up images showed a persistence of the hyperreflective MA-coagulates with a beginning decrease of surrounding retinal thickness. Changes at the level of the RPE, measured by SD- and PS-OCT, indicated a more intense reaction with an increase of hyperreflective tissue in group 2 than in group 1. During follow up changes of the MA and RPE persisted over the course of the study while retinal thickness further decreased. Fluorescence angiography imaging at month 3 showed an involution of treated MA in 13 of 15 eyes.
Following 577nm photocoagulation, morphologic changes were rather confined to the treated microaneurysms, whereas following 532 nm photocoagulation there was stronger increase in hyperreflective, RPE-like tissue underneath the treated MA. These findings corroborate the stronger absorption of the 577nm wavelength in hemoglobin than the 532nm wavelength.
Clinical Trial: :
This PDF is available to Subscribers Only