Rationale: Earlier studies have shown that laser photocoagulation treatments are associated with good long-term visual acuity in most patients with severe nonproliferative diabetic retinopathy (S-NPDR). Histopathologic studies of autopsied eyes have demonstrated defects in the choriocapillaris beneath the retinal laser lesions secondary to photocoagulation for S-NPDR. These lesions have been observed to expand centrifugally over time especially in the posterior pole, and the atrophy of the retinal pigment epithelium (RPE) can be significantly enlarged. There are, however, limited studies detailing the in vivo changes that occur in the RPE and choriocapillaris following laser photocoagulation. Patient concerns: A 46-year-old woman presented with visual disturbances in both eyes. Diagnoses: Fundus examinations showed many retinal hemorrhages and soft exudates in the four quadrants due to S-NPDR. Interventions: Laser photocoagulations with a 532-nm wavelength argon laser with power of 170 to 230 mW and spot size of 200 mm were performed to treat the S-NPDR. The changes in the choriocapillaris and retinal vasculature were followed by optical coherence tomography (OCT) angiography. Outcomes: The choriocapillaris beneath the laser spots was disrupted from 1 hour following the photocoagulation but it was restored at week 2. The choriocapillaris appeared almost normal at some laser spots, but they were still some spots that were altered at 1 year. The outer retina and RPE were disrupted beneath the laser spots at 1 year. On the contrary, there were no visible retinal vascular changes in the superficial and deep plexuses of retinal vasculature determined by OCT angiography with manual and automated segmentation. Lessons: The choriocapillaris in human eyes can recover after laser photocoagulation although the outer retina and RPE remain disrupted and do not recover.
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