The Evolution and Visual Prognosis of Glial Proliferation with Different Grades after Macular Hole Surgery: An Optical Coherence Tomography-Based Study

Introduction: The glial proliferation after macular hole (MH) surgery was divided into two types previously: those replacing the entire intraretinal layer and those involving only the inner foveal layers. The evolution and prognosis of the former type were elaborated on in previous studies, but the latter one has received limited attention. Therefore, this study aims to investigate the evolution of glial proliferation with varying grades after MH surgery and its effects on foveal microstructure and best-corrected visual acuity (BCVA). Methods: In this retrospective research, we reviewed 202 eyes from 196 consecutive patients who underwent a successful idiopathic MHs repair. Based on optical coherence tomography images, glial proliferation was classified into three types: A-type, which replaced the entire intraretinal layer; B-type, located at the level of and above the external limiting membrane (ELM); and C-type, situated above the ELM. Results: Of the 67 eyes that attended the 1-, 4-, and 10-month follow-up, A-type, B-type, C-type, and no glial proliferation were identified in 27 (40.3%), 17 (25.4%), 20 (29.8%), and 3 eyes (4.5%), respectively, at 1 month. Within 10 months, the prevalence of A-type glial proliferation significantly decreased (p < 0.001), but the changes in B-type (p = 0.261), C-type (p = 0.151), and no glial proliferation (p = 0.492) were not significant. In 32 of the 67 eyes, the grade of glial proliferation gradually improved, with A-type transforming into B- or C-type in 19 of 27 eyes (70.4%), B-type into C-type or no glial proliferation in 11 out of 17 eyes (64.7%), and C-type gradually disappearing in 2 out of 20 eyes (10.0%). Among the eyes that attended at least one follow-up (1 M, 202 eyes; 4 M, 161 eyes; 10 M, 97 eyes), those with A-type glial proliferation showed the most defective outer retinal layers, worst BCVA, and thinnest central fovea compared with the other two types at all follow-up time points (p < 0.001). Eyes with C-type glial proliferation exhibited significantly better photoreceptor layer status and BCVA compared with those with B-type glial proliferation. A-type glial proliferation at 1 month, which showed significant association with BCVA at 10 months, could be accurately predicted by the minimum linear diameter with a cut-off >547.5 μm (p < 0.001). Conclusion: Within 10 months, A-type glial proliferation substantially resolves but the prevalence of B- and C-type remains unchanged. B-type glial proliferation hinders the restoration of photoreceptors and impairs visual recovery despite being located within the inner retina.