Abstract
Purpose :
To determine the prevalence of anisometropia in a clinical population, investigate its effect on visual acuity and stereoacuity, and evaluate the spectacle prescribing pattern for anisometropia.
Methods :
This retrospective database review included 4272 patients aged 2-70 years old without ocular pathology who had an eye examination between 1st January and 31st December 2016 at the Hong Kong Polytechnic University Optometry Clinics. Data extracted included logMAR visual acuity (VA) with full subjective refraction, stereoacuity in seconds of arc (arcsec), refractive error, and final spectacle prescription. Anisometropia was defined as inter-eye spherical equivalent refraction (SER) difference >1.00D, and/or cylindrical (CYL) refractive error ≥1.50DC. Data are median (IQR), mean±SD, or unstandardised coefficient β, 95% confidence interval 95%CI.
Results :
Anisometropia was present in 702 (16.5%) patients with mean 1.97±1.41D inter-eye SER difference. Inter-eye VA difference was 0.05±0.13 logMAR and 87.6% had <0.1 logMAR difference between the eyes. Greater inter-eye SER difference was associated with a clinically non-significant increase in inter-eye VA difference (poorer VA) (β=0.004 logMAR, 95%CI 0.001 to 0.006, p<0.0001). Stereoacuity of 40 arcsec or better was found in 131/283 (42.6%) patients, while 83.7% were 100 arcsec or better. Full spectacle prescription for anisometropia were prescribed for 65.8% patients while an adjusted correction was given to 34.2% patients, of which 12 patients were given monovision. Adjusted spectacle prescription was weakly associated with inter-eye SER difference (β=-0.07D, 95%CI -0.09 to -0.06, p<0.0001).
Conclusions :
Many anisometropic patients have acceptable VA and stereoacuity with their full subjective refraction. However, many clinicians (34.2%) are inclined to adjust the spectacle correction of anisometropic patients. It is unknown whether partial correction of anisometropia affects visual function. Further investigation is required to understand the usefulness of partial correction of anisometropia and its effects on visual outcomes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.