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K. Yasuda, M. Shimura, S. Ota, M. Tamai; Retinal Thickness Before and After Pan Retinal Photocoagulation in Patients With More Severe Diabetic Retinopathy but Intact Visual Acuity . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3990.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Pan retinal photocoagulation (PRP) is a currently standard therapy for patients with "more severe diabetic retinopathy". After the completion of this therapy, some patients improved or maintained their visual acuity (VA), but some lost. In this study, with the use of optical coherence tomography (OCT), retinal thickness (RT) around the macular area was measured before and after the PRP in patients with more severe diabetic retinopathy whose VA were not impaired , and investigated the relationship between RT before and after the PRP and final VA. Methods: Forty three eyes of 37 patients with severe nonproliferative or early proliferative retinopathy whose VA was 20/20 or better were recruited in this study. PRP was designed to be completed in 4 sessions and performed biweekly. Before and after the PRP, VA with Snellen chart and RT with OCT retinal map was monitored. OCT retinal mapping program calculated numeric average of retinal thickness in the central area (ϕ 1,000 µm circle), parafoveal area (ϕ 1,000 to 2,220 µm ring) and perifoveal area (ϕ 2,220 to 3,450 µm ring). Results: After the PRP, final VA (more than 6 months after the PRP) was maintained in 36 of 43 eyes (group A), in contrast, decreased more than 2 lines in 7 eyes (group B). There were statistically significant differences between two groups in the following parameters. Before PRP, average RT in the central circle was 187.3 ± 9.5 µm (Group A) and 238.2 ± 18.4 µm (Group B). At the para- and perifoveal area, RT was 241.3 ± 8.6 µm, 244.5 ± 9.2 µm in group A, in contrast 391.8 ± 22.3 µm, 402.6 ± 21.3 µm in group B. In the group A, after the first session of PRP, RT in the central ring was increased 1.1 ± 0.1 times thicker than initial thickness, in contrast 1.28 ± 0.4 times thicker in the group B. Conclusions: In this study, there found at least two risk factors which caused decrease of VA after PRP treatment against patients with more severe diabetic retinopathy. One is a thickening macula before PRP, and the other is a prominent increase of macular thickness after the first session of the PRP.
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