Abstract
Purpose :
To evaluate retinal structural changes with spectral domain optical coherence tomography (SD-OCT) after threshold and subthreshold focal/grid photocoagulation for macular edema using navigated laser (Navilas, OD-OS Inc., Berlin).
Methods :
Laser burns were longitudinally analyzed with spectral domain optical coherence tomography (SD-OCT, Heildelberg Engineering) after navigated laser treatment at 1/2 hour, month 1, 3 and 6. All laser burns were classified into threshold, barely visible and subthreshold burns using color fundus photography. Retinal thickness (RT) was measured and retinal layers were analyzed regarding visibility of laser burns and localization of retinal structural changes. Paired T-Test was used to compare RT at different time points.
Results :
A total of 149 laser applications out of 7 eyes were analyzed. Threshold laser was characterized as a visible laser burn on color fundus photography. Retinal layers of threshold and barely visible burns visualized on SD-OCT clearly showed structural changes of inner and outer retinal layers. After threshold laser, persistence of inner segment/outer segment junction damage was noted at month 6. Subthreshold laser burns also demonstrated structural retinal changes with milder damage of outer retinal layers shown as swelling of retinal pigment epithelium (RPE) at month 1 and 3, that recovered at month 6. RT thickness was significantly reduced by threshold, barely visible and subthreshold laser burns after 3 and 6 months of laser treatment (p < 0.005).
Conclusions :
Navigated laser photocoagulation allows the localization of subthreshold laser burns that are not visible in color photography. Threshold, barely visible and subthreshold laser burns can all show structural changes of retinal layers in SD-OCT.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.