Centre for Vision across the Life Span, School of Applied Sciences, University of Huddersfield, United Kingdom.
Goethe University Hospital, Department of Ophthalmology, Child Vision Research Unit, Frankfurt, Germany.
Invest Ophthalmol Vis Sci. 2024 Aug 1;65(10):33. doi: 10.1167/iovs.65.10.33.
Crowding is exaggerated in central vision of strabismic amblyopia, impacting on reading ability. Crowding magnitude and interocular differences (IODs) in acuity are indicators for detection, assessment, and monitoring of treatment. Lateral masking (including contour interaction) also affects acuity and can mimic or ameliorate crowding. We investigated lateral masking/contour interaction and crowding impact on crowding magnitude and IOD measures in healthy and amblyopic pediatric and juvenile/adult groups using two Landolt C-tests with "fixed" arcmin separations.
Acuity (logMAR) was measured with Landolt C-tests with specified 2.6' ("crowded") and 35' ("uncrowded") separations. Crowding magnitudes (crowded - uncrowded acuities) and IODs were calculated. Participants were 69 subjects with strabismic amblyopia (n = 39 pediatric, i.e. children ≤8 years of age), 31 subjects with anisometropic amblyopia (n = 14 pediatric), and 76 healthy controls (n = 36 pediatric). Subjects with amblyopia were subgrouped by acuity as low severity (<0.4 logMAR) or high severity (≥0.4 logMAR) using the 35' separation C-test.
Crowding magnitudes were greater in strabismic than in anisometropic amblyopia and control/fellow eyes. They were higher in pediatric control/fellow eyes than in juvenile/adult eyes. In high severity strabismic amblyopia, crowding magnitudes progressively and significantly reduced (slope = -0.17 ± 0.07, P < 0.05) with worsening acuity. IODs for this group were higher on the 2.6' C-test, but lower than expected. In high severity pediatric subjects with anisometropic amblyopia, seven of eight had lower IODs measured with the "crowded" than the "uncrowded" C-tests.
These C-tests detect amblyopia but underestimate crowding in children and adults with high severity strabismic amblyopia. Separate isolated optotype acuity and crowding distance tests may better target specific functions, while minimizing the impact of masking.
斜视性弱视的中央视力中存在夸大的拥挤现象，这会影响阅读能力。拥挤程度和视力的眼间差异（IOD）是检测、评估和监测治疗的指标。横向掩蔽（包括轮廓相互作用）也会影响视力，并可能模拟或改善拥挤现象。我们使用两个具有“固定”弧分分离的 Landolt C 测试，研究了横向掩蔽/轮廓相互作用以及拥挤对健康和弱视的儿科和青少年/成人组的拥挤程度和 IOD 测量值的影响。
使用 Landolt C 测试测量视力（logMAR），并具有指定的 2.6'（“拥挤”）和 35'（“不拥挤”）分离。计算拥挤程度（拥挤 - 不拥挤视力）和 IOD。参与者包括 69 名斜视性弱视患者（n = 39 名儿科患者，即≤8 岁的儿童）、31 名屈光不正性弱视患者（n = 14 名儿科患者）和 76 名健康对照者（n = 36 名儿科患者）。使用 35' 分离的 C 测试，根据弱视患者的视力将其分为低严重度（<0.4 logMAR）或高严重度（≥0.4 logMAR）亚组。
斜视性弱视的拥挤程度大于屈光不正性弱视和对照组/同眼。儿科对照组/同眼的拥挤程度高于青少年/成人眼。在高严重度斜视性弱视中，随着视力的恶化，拥挤程度逐渐显著降低（斜率=-0.17±0.07，P<0.05）。该组的 IOD 在 2.6' C 测试中较高，但低于预期。在高严重度的屈光不正性弱视的儿科患者中，有 8 例中的 7 例在“拥挤”C 测试中测量的 IOD 低于“不拥挤”C 测试。
这些 C 测试可检测弱视，但在患有高严重度斜视性弱视的儿童和成人中会低估拥挤程度。单独的孤立视标视力和拥挤距离测试可能更好地针对特定功能，同时最大限度地减少掩蔽的影响。
