Purpose: To identify the morphologic changes secondary to macular grid photocoagulation in diabetic macular edema in vivo using spectral domain optical coherence tomography.
Methods: In this prospective cohort study, 13 consecutive patients with vision loss because of clinically significant macular edema associated with diabetes mellitus Type 2 underwent grid laser treatment (PASCAL). Best-corrected visual acuity, Spectralis optical coherence tomography, infrared fundus imaging, and biomicroscopy were performed at baseline, Day 1, Week 1, and Months 1, 2, and 3 after treatment. Fluorescein angiography was performed at baseline and at 3 months.
Results: Mean central 1-mm thickness decreased significantly from 438 ± 123 μm (mean ± SD) at baseline to 391 ± 111 μm (P < 0.05) at 3 months with a nonsignificant trend of best-corrected visual acuity improvement. A wipeout of the photoreceptor layer and the inner segment/outer segment line together with an alteration of the overlaying outer nuclear layer and external limiting membrane was seen at Day 1. The lesion was reduced to a focal hyperreflective deposit on the retinal pigment epithelium boundary. In 55% of lesions, the external limiting membrane as well as the previously interrupted inner segment/outer segment line revealed intact continuity at Month 3. In some areas, repair was incomplete indicated by a focal condensation interrupting the inner segment/outer segment line in the lesion center.
Conclusion: In vivo imaging of morphologic lesion repair in human eyes after PASCAL grid laser of diabetic macular edema demonstrates progressive restoration of the external limiting membrane and inner segment/outer segment integrity as previously described in animal models.