Abstract
Purpose: :
Candy et al (2011) recently found that the accommodative lag for a target at 50 cms in children between 6 months and 7 years of age is associated with high hyperopia (> +5.00 D), amblyopia, and strabismus. The accommodative lag of the least accurate meridian under binocular viewing conditions, prior to any treatment or intervention, gave a sensitivity of 83% and a specificity of 97% for a criterion of 1.30 D using an ROC analysis. This analysis was extended to younger subjects in the current study to evaluate the age range over which this approach might be taken.
Methods: :
An automated form of Nott retinoscopy was performed through a beamsplitter while typically developing infants watched a movie on an LCD screen with a broadband spatial frequency amplitude spectrum. The infants, from three to four months of age, were tested in binocular viewing while the stimulus was positioned at 25, 33, and 50 cms. Refractive error was determined at the same visit with cycloplegic retinoscopy using one drop of 0.5% cyclopentolate in each eye.
Results: :
Of 39 infants tested, 30 (77%), 36 (92%), and 21 (54%) were able to complete accommodative testing at 25, 33, and 50 cms respectively. An ROC analysis of accommodative lag to detect infants with hyperopia greater than +4.00 D was generated for each stimulus distance.The area under the curve (AUC) was 0.63, 0.74, and 0.75 at 25, 33, and 50 cms, respectively. Sensitivity and specificity values were determined from the ROC analyses. A failure criterion of ≥ 1.95 D at the 33cm viewing distance gave a sensitivity of 100%, specificity of 70%, and percent correctly identified of 75%.
Conclusions: :
The prevalence of hyperopia greater than +4.00D is higher at 3 to 4 months of age than at older ages and these infants are at risk for developing amblyopia and strabismus if they do not emmetropize. Similar to the findings of Candy et al (2011), the results of this study suggest that a relatively simple test for accommodative accuracy may detect a significant proportion of the infants at risk. This is further supported by the previous findings of Ingram and colleagues amongst others, who have suggested that increased lag is associated with greater risk.
Keywords: hyperopia • accommodation • infant vision