Pathologic myopia in highly myopic patients with high axial anisomyopia

PurposeTo determine prevalence of anisomyopia (axial length (AL) difference >= 2.5 mm) among high myopes ((HMs), defined by spherical equivalent of <= 6.0 diopters or AL >= 26.5 mm). To characterise the shorter anisomyopic eye (SAE) and evaluate if pathologic myopia (PM) in the longer anisomyopic eye (LAE) was associated with increased risk of PM in the SAE. Methods1168 HMs were recruited from Singapore National Eye Centre clinic for this cross-sectional study. Biometry, fundus photography and swept-source optical coherence tomography were performed. Patients with high axial anisomyopia were identified. Structural characteristics and presence of PM were described. Stepwise multivariate regression explored associations between PM in the LAE and pathology in the SAE, controlling for confounding variables. ResultsPrevalence of anisomyopia was 15.8% (184 of 1168 patients). Anisomyopic patients (age 65.8 +/- 13.5 years) had mean AL of 30.6 +/- 2.0 mm and 26.2 +/- 2.3 mm in the LAE and SAE, respectively. 52.7% of SAEs had AL < 26.5 mm. Prevalence of myopic macular degeneration, macula-involving posterior staphyloma (PS), myopic traction maculopathy (MTM) and myopic choroidal neovascularisation (mCNV) in the SAE was 52.2%, 36.5%, 13.0% and 8.2%, respectively. Macular hole in the LAE was associated with increased risk of MTM in the SAE (OR=4.88, p=0.01). mCNV in the LAE was associated with mCNV in the SAE (OR=3.57, p=0.02). PS in the LAE was associated with PS in the SAE (OR=4.03, p<0.001). ConclusionsEven when controlled for AL, PM complications in the LAE predict similar PM complications in the SAE. Patients with high axial anisometropia with PM in the LAE should be monitored carefully for complications in the SAE.