Estimation of high myopia-associated optic neuropathies: the Two-Continent Eye Study.

PURPOSE: To estimate probabilities of high myopia-associated glaucomatous/glaucoma-like optic neuropathy (GLON) and non-glaucomatous optic neuropathy (NGON).

METHODS

Participants of four population-based investigations (Beijing Eye Study (n=3316 participants; age: 40+ years), Ural Eye and Medical Study (n=5372; age: 40+ years), Ural Very Old Study (n=586; age: 85+ years), Ural Children Eye Study (n=4328; age: 6+ years), Central India Eye and Medical Study (n=4374; age: 30+ years) underwent medical and ophthalmological examinations.

RESULTS

The study population (n=35 167 eyes; 17 996 individuals) was randomly divided (ratio: 1:1) into a development and validation subgroup. In the development subgroup, the GLON prevalence equation was: -20.221+0.359×Axial Length+0.083×Age+0.706×Indian Ethnicity+0.198×Intraocular Pressure (IOP)+0.780×NGON-Presence. The NGON prevalence equation was: -38.136+1.202×Axial Length+0.038×Age-2.745×Indian Ethnicity+0.566×Myopic Macular Degeneration Stage+1.300×GLON Presence. In the validation subgroup, these equations had an area under the receiver operating characteristic curve for GLON prevalence and NGON prevalence of 0.881 and 0.964, respectively. Applying the equations, a non-Indian individual (axial length: 28 mm; IOP: 22 mm Hg) had a GLON probability of 3.5% and 60.2% at the ages of 30 years and 75 years, respectively, and an NGON probability of 3.42% and 16.4%, respectively. With an axial length of 30 mm, GLON probability and NGON probability increased from 6.9% to 75.6% and from 28.2% to 68.4% from age 30 years to 75 years.

CONCLUSIONS

The equations offer a rough estimate of optic nerve damage probability at present and at older age, based on axial length, IOP, ethnicity and ocular comorbidity. The calculated probability of GLON and NGON (IOP: 22 mm Hg, age: 75 years) at an axial length of 28 mm was 60.2% and 16.4%, respectively, and 75.6% and 68.4%, respectively, for an axial length of 30 mm.