Convergence and Accommodation Development Is Preprogrammed in Premature Infants.
OBJECTIVE
This study investigated whether vergence and accommodation development in preterm infants is preprogrammed or is driven by experience.


METHODS
Thirty-two healthy infants, born at mean 34 weeks gestation (range, 31.2-36 weeks), were compared with 45 healthy full-term infants (mean 40.0 weeks) over a 6-month period, starting at 4 to 6 weeks postnatally. Simultaneous accommodation and convergence to a detailed target were measured using a Plusoptix PowerRefII infrared photorefractor as a target moved between 0.33 and 2 m. Stimulus/response gains and responses at 0.33 and 2 m were compared by both corrected (gestational) age and chronological (postnatal) age.


RESULTS
When compared by their corrected age, preterm and full-term infants showed few significant differences in vergence and accommodation responses after 6 to 7 weeks of age. However, when compared by chronological age, preterm infants' responses were more variable, with significantly reduced vergence gains, reduced vergence response at 0.33 m, reduced accommodation gain, and increased accommodation at 2 m compared to full-term infants between 8 and 13 weeks after birth.


CONCLUSIONS
When matched by corrected age, vergence and accommodation in preterm infants show few differences from full-term infants' responses. Maturation appears preprogrammed and is not advanced by visual experience. Longer periods of immature visual responses might leave preterm infants more at risk of development of oculomotor deficits such as strabismus.
Infant Vision Laboratory School of Psychology & Clinical Language Sciences, University of Reading, Reading, United Kingdom 2Orthoptic Department, Royal Berkshire Hospital, Reading, United Kingdom.
Anna M
AM
Horwood
Infant Vision Laboratory School of Psychology & Clinical Language Sciences, University of Reading, Reading, United Kingdom.
Sonia S
SS
Toor
Infant Vision Laboratory School of Psychology & Clinical Language Sciences, University of Reading, Reading, United Kingdom.
Patricia M
PM
Riddell
D000065:Accommodation, Ocular / Q000502:physiology*; D002675:Child, Preschool; D003290:Convergence, Ocular; D003463:Cues; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D007235:Infant, Premature, Diseases / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D013285:Strabismus / Q000151:congenital / Q000175:diagnosis / Q000503:physiopathology*; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*