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Sensitivity in the nasal and temporal hemifields in children treated for cataract
E R Bowering1, D Maurer, T L Lewis
1Department of Psychology, Mount St. Vincent University, Halifax, Nova Scotia, Canada.
Insights
Form-deprived aphakes show reduced peripheral visual sensitivity, particularly in the nasal field, due to early visual pathway competition. This impacts functions slow to mature, like nasal sensitivity.
Area of Science:
- Ophthalmology
- Neuroscience
- Developmental Biology
Background:
- Form deprivation in early development can impact visual system maturation.
- Understanding visual field development in aphakia is crucial for early intervention.
Purpose of the Study:
- To investigate if form-deprived aphakes exhibit reduced nasal visual field sensitivity.
- To examine how timing, duration, and type of deprivation (monocular vs. binocular) affect peripheral sensitivity.
Main Methods:
- Static perimetry was used to measure visual sensitivity thresholds in normal subjects and children with congenital cataracts.
- Testing occurred at 20 degrees nasal and 30 degrees temporal visual fields.
- Patient groups included those with unilateral or bilateral congenital cataracts and adults with late-onset cataracts.
Main Results:
- Normal subjects showed slightly better nasal than temporal sensitivity.
- Children with unilateral congenital cataracts had greater nasal sensitivity loss compared to temporal loss.
- Deprivation duration and fellow eye patching did not significantly affect sensitivity; adult-onset cataracts did not impair sensitivity.
Conclusions:
- Pattern deprivation disrupts peripheral visual sensitivity development.
- Early monocular deprivation has a more pronounced effect on slower-maturing nasal sensitivity than binocular deprivation.
- Results support the hypothesis that interocular competition in infancy affects immature visual functions.
Purpose:
To determine if form-deprived aphakes, like normal infants, show especially poor sensitivity in the nasal visual field. The purpose of this article was also to examine the influence on their peripheral sensitivity of the timing and duration of deprivation, of whether deprivation was monocular or binocular, and of having patched the fellow nondeprived eye.
Methods:
Static perimetry was used to measure intensity thresholds at 20 degrees in the nasal visual field and at 30 degrees in the temporal visual field in normal subjects (n = 20 7-year-old children, 20 8-year-old children, 12 9-year-old children, and 20 adults) and in 46 children treated for a dense and central cataract in one (n = 21) or both (n = 25) eyes. The deprivation began either at birth or after a normal early history, and the duration of deprivation varied widely among patients. Also tested were two adults who had been treated promptly for unilateral cataracts that had developed after the age of 40 years.
Results:
In normal subjects, sensitivity was slightly higher at 20 degrees nasally than at 30 degrees temporally, with no developmental changes in sensitivity at either location. The deprived eyes of the children had losses in sensitivity at both locations but only children treated for unilateral congenital cataract had larger losses at 20 degrees nasally than at 30 degrees temporally. There were no significant effects on their sensitivity of the duration of deprivation or, in children treated for unilateral cataract, of patching of the nondeprived eye. In contrast, the two patients in whom cataracts did not develop until adulthood had normal sensitivity.
Conclusions:
Pattern deprivation interferes with the development of peripheral sensitivity at both 30 degrees temporally and 20 degrees nasally. Nasal sensitivity, which is slow to mature, is affected more by early monocular deprivation than by early binocular deprivation. The results are consistent with the hypothesis that unfair interocular competition during early infancy especially affects visual functions that are slow to mature.