Purpose: High myopia and pathologic myopia are common causes of visual morbidity. Myopic pathology can affect all regions of the retina, though there is currently no classification system to distinguish anterior (peripheral) and posterior (macular) pathology. We hypothesize that these classifications are characterized by distinct demographic and refractive features, highlighting the disparity in types of pathologic myopia.
Methods: Institutional retrospective cohort study. The Stanford University Medical Center Clinical Data Warehouse was used to identify patients with high myopia by ICD-9 and ICD-10 codes. Predetermined ICD diagnoses were then used to classify patients with high myopia into isolated high myopia (IHM), anterior pathologic myopia (APM), posterior pathologic myopia (PPM), and combined pathologic myopia (CPM). A cohort of this population was then manually reviewed to gather refractive data and confirm accuracy of ICD coding.
Results: Patients (3274) were identified with high myopia. Overall, 22.1% individuals met criteria for APM, 10.7% for PPM, 17.0% for CPM, and 50.2% for IHM. We identified a significantly higher frequency of females with PPM compared to APM (62.3 vs. 48.3%; OR, 1.73; 95% CI, 1.34 to 2.25), Asian patients with PPM as compared to APM (42.9 vs. 33.3%; OR, 1.50; 95% CI, 1.16 to 1.95), and younger patients with APM compared to PPM (median 45.3 vs. 63.4 years). The refractive error was significantly more myopic in the CPM (median - 9.8D; interquartile range, IQR 6.7) and PPM (median - 10.5D; IQR 9.8) subgroups as compared to the APM (median - 8.1D; IQR 3.5), and IHM (median - 8.2D; IQR 4.1) subgroups (p = 0.003).
Conclusions: High myopia may be divided into four distinct subgroups based on presence and location of pathology, which is associated with differences in age, gender, race, and refractive error.
Keywords: Anterior pathologic myopia; Classification; Combined pathologic myopia; Epidemiology; High myopia; Isolated high myopia; Pathologic myopia; Posterior pathologic myopia; Retina.