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Published on: March 3, 2023
Gender differences in early accommodation and vergence development
Anna M Horwood1, Patricia M Riddell
1Infant Vision Laboratory, School of Psychology & Clinical Language Sciences, University of Reading, Earley Gate, Reading, UK. a.m.horwood@reading.ac.uk
Insights
Infant visual development shows rapid maturation of vergence and accommodation responses by 4 months. Gender differences in visual responses are observed in early infancy but diminish over time.
Area of Science:
- Ophthalmology
- Developmental Neuroscience
- Pediatric Vision
Background:
- Binocular vision, encompassing vergence and accommodation, is crucial for visual development.
- Understanding the maturation of these responses in infants is key to identifying potential visual anomalies early.
Purpose of the Study:
- To objectively assess the development of binocular vergence and accommodation responses in infants aged 1-6 months.
- To investigate potential gender-specific differences in these visual functions during early development.
Main Methods:
- A remote haploscopic photorefractor was utilized to measure objective vergence and accommodation.
- 157 healthy, full-term infants aged 1-6 months were tested while fixating a moving target at various distances.
- Response gain and intercept were analyzed for both accommodation and vergence.
Main Results:
- Vergence and accommodation response gains matured rapidly, reaching adult-like levels by 4 months.
- Males exhibited higher accommodation gain and a more appropriate accommodative intercept in the first 3 months.
- Gender differences in visual responses were noted in early infancy but disappeared after 3 months.
Conclusions:
- Infant vergence and accommodation mature quickly, with significant gender-related differences in the first three months.
- These early differences may relate to refractive errors or distinct sensory cue preferences (blur vs. disparity).
- Further research is needed to fully elucidate the mechanisms behind these observed gender differences in visual development.
Abstract:
A remote haploscopic photorefractor was used to assess objective binocular vergence and accommodation responses in 157 full-term healthy infants aged 1-6 months while fixating a brightly coloured target moving between fixation distances at 2, 1, 0.5 and 0.33 m. Vergence and accommodation response gain matured rapidly from 'flat' neonatal responses at an intercept of approximately 2 dioptres (D) for accommodation and 2.5 metre angles(MA) for vergence, reaching adult-like values at 4 months. Vergence gain was marginally higher in females (p = 0.064), but accommodation gain (p = 0.034) was higher and accommodative intercept closer to zero (p = 0.004) in males in the first 3 months as they relaxed accommodation more appropriately for distant targets. More females showed flat accommodation responses (p = 0.029). More males behaved hypermetropically in the first two months of life, but when these hypermetropic infants were excluded from the analysis, the gender difference remained. Gender differences disappeared after three months. Data showed variable responses and infants could behave appropriately and simultaneously on both, neither or only one measure at all ages. If accommodation was appropriate (gain between 0.7 and 1.3; r(2) > 0.7) but vergence was not, males over- and under-converged equally, while the females who accommodated appropriately were more likely to overconverge (p = 0.008). The apparent earlier maturity of the male accommodative responses may be due to refractive error differences but could also reflect gender-specific male preference for blur cues while females show earlier preference for disparity, which may underpin the earlier emerging, disparity dependent, stereopsis and full vergence found in females in other studies.
