Adults with high myopia and myopic macular degeneration (MMD) may have visual field loss, even in patients without glaucoma, according to research published in the British Journal of Ophthalmology.
Researchers conducted a cross-sectional study to determine if and how MMD manifests visual defects and functional parameters distinct from glaucoma.
Color fundus photographs were obtained for each eye with standardized settings through a nonmydratic retinal camera, then graded via the International Photographic Classification and Grading System for Myopic Maculopathy protocol (Meta-PM). Eyes were defined as having MMD if Meta-PM category was 2, 3, or 4, or if any “plus” lesions were noted.
The researchers performed visual field tests using Humphrey central 24-2 threshold, white-on-white automated perimetry. They also gathered measurements for autorefraction, spherical equivalent, axis length, and demographic data via a questionnaire.
The study cohort included 106 participants and 181 eyes with high myopia (48.1% men, mean age, 55.4±9.9 years). Mean axis length was 26.7±1.1 mm and mean intraocular pressure (IOP) was 14.4±2.9 mm Hg. Eleven percent of eyes were Meta-PM category 1, 62.4% were category 1, 25.4% were category 2, and 1.1% were category 3. Of the eyes in category 2, 1 eye demonstrated lacquer cracks (“plus” lesions).
Participants with both high myopia and MMD were significantly older, at 61.8±6.8 years, were less likely to be Chinese (18.3%) and had a longer axis length (27.5±1.3 mm) compared with those with high myopia without MMD.
Investigators also noted a significantly higher proportion of abnormal visual fields in participants with high myopia and MMD (62.5% vs 28.6%). The overall visual field defects were worse in those with significantly higher mean deviation — that is, those with more negative value — in the high myopia with MMD group. (-3.8±2.9 dB vs -1.1±1.4 dB in high myopia without MMD.
Mean deviation was also worse in higher Meta-OM categories, as well as in pattern SD. Two eyes in Meta-PM category 3 demonstrated abnormal visual field, which showed a general loss of sensitivity.
The research shows a significantly higher proportion of eyes with MMD that had optic disc tilt (43.8% vs 20.3%), and a significantly higher proportion of PPA (97.9% vs 76.5%). Other optic disc morphological features and intraocular pressures were not significantly different between those with and without MMD.
Patterns of visual field defects were significantly different between those with high myopia and MMD and those with high myopia without MMD, with a greater generalized sensitivity loss and arcuate defects. Of the 6 eyes with arcuate defects, 5 had MMD and partial arcuate defects.
Results of a multivariable logistic regression GEE analysis, which adjusted for age, sex, race, education level, and axis length, higher visual field loss was associated with myopic macular degeneration, and with ever -1 dB increased in mean deviation, odds of MMD were 1.52. Higher pattern standard deviation, optic disc tilt, and presence of peripapillary atrophy were also associated with MMD (adjusted ORs, 1.67, 3.36, and 18.53, respectively).
Study limitations include the cross-sectional design and an inability to determine if some participants had undiagnosed normal tension glaucoma or preglaucomatous lesions.
“Individuals with MMD have greater visual function loss as measured by static automated perimetry when compared with individuals without MMD,” the research shows. “[Visual field] defects in older adults may be attributable to MMD and not glaucoma.”
Disclosure: One study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Lanca C, Sun CH, Chong R, et al. Visual field defects and myopic macular degeneration in Singapore adults with high myopia. Br J Ophthalmol. Published online April 22, 2201. doi:10.1136/bjophthalmol-2020-318674