Visual Acuity and Size of Choroidal Neovascularization in Highly Myopic Eyes with a Dome-Shaped Macula

INTRODUCTION: A dome-shaped macula (DSM) is an inward convexity or anterior deviation of the macular area. DSM is believed as a protective factor in maintaining visual acuity in highly myopic eyes. OBJECTIVE: To investigate the correlation between best-corrected visual acuity (BCVA), choroidal neovascularization (CNV), and a dome-shaped macula (DSM) in highly myopic eyes. METHODS: In this retrospective and observational case series study, BCVA tests and optical coherence tomography (OCT) were performed in a total of 472 highly myopic eyes (refractive error ≥6.5 diopters or axial length ≥26.5 mm). CNV was detected by fundus fluorescein angiography (FFA), and the CNV area was measured by ImageJ software. BCVA, central retinal thickness (CRT), and the CNV area were compared between highly myopic eyes with and without DSM. RESULTS: The data revealed 13 eyes with DSM complicated by CNV, for an estimated prevalence of 25%. The eyes with CNV in the DSM group showed worse BCVA than those in the non-DSM group (1.59 ± 0.69 and 0.63 ± 0.64, respectively, p < 0.05), and the CNV area in the DSM group was larger than that in the non-DSM group (2793.91 ± 2181.24 and 1250.71 ± 1210.36 pixels, respectively, p < 0.05). After excluding the eyes with CNV, the DSM group had better BCVA than the non-DSM group (0.33 ± 0.17 and 0.44 ± 0.48, respectively, p < 0.05); however, no significant difference was observed in the CRT of eyes with CNV between the DSM group and the non-DSM group. CONCLUSION: These results show that DSM might be a protective mechanism for visual acuity, but its protective capability is limited. DSM eyes have better visual acuity within the protective capability. If a more powerful pathogenic factor exceeding the protective capability is present, then the eye will have more severe CNV and worse visual acuity.