Intereye differences in myopic macular degeneration, intraocular pressure and axial length: the Two-Continent Eye Study

Purpose To assess associations of myopic macular degeneration (MMD) with intraocular pressure (IOP). Methods The project included the population-based Beijing Eye Study (n=3335 participants; age: 40+ years), Ural Eye and Medical Study (n=5589; age: 40+ years), Ural Very Old Study (n=566; age: 85+ years) and Ural Children Eye Study (n=4325; age: 6+ years) and Central India Eye and Medical Study (n=4514; age: 30+ years). MMD was defined according to the Meta-analysis for Pathologic Myopia Study Group. Results The study population included 35 778 eyes (18 328 individuals) (age: 46.9±23.1 years; range: 6–100 years) (axial length: 23.2±1.0 mm; range: 18.08–34.20 mm). Longer axial length was associated with higher IOP (ß:0.03; p<0.001) with adjusting for age (ß:0.01; p<0.001), sex (ß:−0.19; p=0.006) and MMD-stage (ß:0.47; p<0.001). Intereye axial length difference correlated (r 2 =0.11) with higher intereye difference in IOP (ß: 0.03; p<0.001) after adjusting for age (ß: 0.06; p<0.001), sex (ß: −0.07; p<0.001) and higher intereye difference in MMD-stage (ß: 0.32; p<0.001). Higher intereye IOP difference correlated (r 2 =0.03) with higher intereye axial length difference (ß: 0.03; p<0.001) after adjusting for age (ß: −0.15; p<0.001), but not with intereye difference in MMD-stage (p=0.90). Higher intereye difference in MMD-stage was associated (r 2 =0.10) only with higher intereye axial length difference (ß: 0.32; p<0.001) and sex (ß: 0.01; p=0.04). Higher intereye difference in MMD prevalence (defined as MMD-stage 3+) correlated with intereye axial length difference (ß: 0.24; p<0.001) and female sex (ß: 0.02; p=0.006) but not with intereye IOP difference (p=0.14). Conclusions Although IOP was associated with longer axial length, MMD stage and MMD prevalence were not significantly related to IOP, neither in an interindividual comparison nor in an intraindividual intereye comparison. The data point against a therapeutic IOP reduction as a measure to reduce development or progression of MMD.