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Ocular Focusing Behavior of the One-Eyed Child
N Geetha Sravani1, Shrikant R Bharadwaj
1*BSOpt †BSOpt, PhD Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation (NGS, SRB), and Bausch and Lomb School of Optometry, Brien Holden Institute of Optometry and Vision Sciences (SRB), L V Prasad Eye Institute, Hyderabad, Telangana, India.
Insights
Children with only one functional eye have accommodative gain between typical binocular and monocular responses. Their accommodative gain did not increase with a demanding reading task, unlike controls.
Area of Science:
- Ophthalmology
- Pediatric Vision
- Neuroscience
Background:
- Binocular vision is crucial for depth perception and visual development.
- Understanding visual responses in children with uniocular vision provides insights into visual plasticity and adaptation.
- Previous research has focused on visual acuity, but accommodative and pupil responses in uniocular children require further investigation.
Purpose of the Study:
- To compare accommodative gain and pupil miosis in children with one functional eye to age-matched controls.
- To assess the impact of a cognitively demanding task on visual responses in uniocular and binocular children.
- To investigate correlations between age, duration of visual deficit, and visual responses in uniocular children.
Main Methods:
- A comparative study involving 41 uniocular children and 43 typically developing controls (ages 3-14).
- Participants viewed an LCD screen with changing distances, performing tasks binocularly and monocularly (controls) or with their single functional eye (cases).
- Accommodative and pupil responses were measured using the Plusoptix PowerRef3 photorefractor during movie viewing and reading tasks.
Main Results:
- Uniocular children exhibited greater accommodative gain than monocular controls but less than binocular controls.
- Pupil miosis in uniocular children was similar to monocular controls and less than binocular controls.
- Accommodative gain did not significantly increase with reading in uniocular children, unlike in controls.
Conclusions:
- Children with uniocular vision have accommodative gain intermediate to typical binocular and monocular responses.
- Uniocular children's accommodative system does not adapt to increased cognitive demand during reading as observed in controls.
- Pupil responses in uniocular children resemble monocular responses of their typically developing peers.
Purpose:
To compare the accommodative gain and pupil miosis of children with only one functional eye with the binocular and monocular accommodative and pupil responses of typically developing age-matched controls.
Methods:
Forty-one uniocular cases and 43 controls (3-14 years for both cohorts) watched a cartoon movie on an LCD screen that ramped between 90 and 30 cm, with a stable period of 4 seconds at both viewing distances. Cases performed the task with their only functional eye whereas controls performed the task binocularly and monocularly. A subset of subjects also repeated the task while reading 20/40-sized letters on the LCD screen. Accommodative and pupil responses were recorded using the Plusoptix PowerRef3 photorefractor.
Results:
Accommodative gain of cases [median (25th-75th IQR): 0.73 (0.60-0.85)] was larger than the monocular gain of controls [0.56 (0.47-0.79)] (P = .03). Both responses were lower than the binocular gain of controls [0.95 (0.81-1.11)] (P < .001). Uniocular pupil miosis of cases [0.14 mm (0.06-0.24 mm)] were similar to monocular [0.12 mm (0.05-0.29 mm)] (P = .69) and smaller than binocular [0.23 mm (0.14-0.34 mm)] (P < .001) responses of controls. The increase in accommodative gain from movie watching to reading was significant only for controls (P = .02) but not for cases (P = .15). Age and time of visual deficit were poorly correlated with accommodative gain and pupil miosis of cases (r ≤ 0.25; P ≥ .1 for all). Age was also poorly correlated with the binocular and monocular accommodative and pupil performance of controls (r ≤ -0.3; P = .33).
Conclusions:
The accommodative gain of children with permanent loss of binocularity is in between the binocular and monocular gains of typically developing children. Their accommodative gains do not show any significant increase with a cognitively demanding task even while such a behavior is observed in controls. Pupil responses of uniocular children are similar to the monocular responses of age-matched controls.
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