Correlation of outer retinal microstucture and foveal thickness with visual acuity after pars plana vitrectomy for complications of proliferative diabetic retinopathy.

PURPOSE

To compare spectral domain optical coherence tomography (SDOCT)-measured macular thickness, outer retinal layers architecture, and best-corrected visual acuity (BCVA) in eyes with proliferative diabetic retinopathy after pars plana vitrectomy.

METHODS

In this retrospective case study, consecutive eyes operated by single surgeon were included. Retinal thickness was measured with SDOCT (Cirrus OCT; Carl Zeiss Meditec, Inc) as follows: automated central 1-mm subfield thickness (CFT), manually measured central foveal point thickness (CPT), integrity of external limiting membrane (ELM), and photoreceptor inner and outer segments (IS/OS). Three vitreoretinal-trained masked experts independently graded ELM and IS/OS layers.

RESULTS

Of the 36 eyes included, 50% were those of women whose mean age was 49 years (range, 24-66 years). Mean preoperative BCVA was 20/600 (range, light perception to 20/80) and mean postoperative follow-up was 19 months (range, 4-43 months). Mean postoperative BCVA improved to 20/80 (range, counting fingers to 20/25; P < 0.0001) with mean SDOCT 1 mm CFT of 260 μm and manual CPT of 236 μm. Mean ELM integrity grade was 1.9 (range, 0-5), while the mean grade of IS/OS integrity was 2.2 (range, 0-5). The correlation coefficients (r) were 0.17 (P = 0.32) for logarithm of the minimum angle of resolution BCVA versus SDOCT automated CFT, 0.192 (P = 0.26) for BCVA versus SDOCT CPT, 0.52 (P = 0.012) for BCVA versus ELM, and 0.55 (P = 0.006) for BCVA versus IS/OS.

CONCLUSION

SDOCT-measured CFT and CPT correlate weakly with BCVA, while ELM and IS/OS integrity correlates well with BCVA. Outer retinal microstructure may represent anatomically better level of postoperative visual function than retinal thickness after pars plana vitrectomy for complications of proliferative diabetic retinopathy.