This study compares retinoscopy in infants using a near noncycloplegic technique, cycloplegia with tropicamide 1%, and cycloplegia with cyclopentolate 1%. The study sample included 29 healthy, nonstrabismic infants 4 to 7 months of age (mean 5.71 months).
Each study subject was examined at two separate visits an average of 2 weeks apart (mean [±SD] 14 ± 9 days). The examiner completed a case history, iris color grading, confrontation tests, and noncycloplegic near retinoscopy in a dark room and then instilled a drop of topical anesthetic in each eye followed by 2 drops of cycloplegic agent separated by 5 min. Retinoscopy was performed 25 to 30 min after the first drops were instilled. The bottles were masked, and the drop administered at the first visit was randomly assigned.
On a scale of 0 to 4.9, the median iris grade was 4.0, which corresponds to a brown or darkly pigmented iris. All reported retinoscopy results are for the horizontal meridian of the right eye. The mean refractive error using noncycloplegic near retinoscopy was +0.94 D (±1.19 D). The mean refractive error was +1.81 D (±1.19 D) with tropicamide and +1.88 D (±1.45 D) with cyclopentolate. There was no statistically or clinically significant difference between the two cycloplegic measurements using different diagnostic agents (t = −0.46, p = 0.65). The mean difference between noncycloplegic and cycloplegic retinoscopy was 0.89 D (±0.66 D) with tropicamide (t = −6.57, p < 0.0001) and 1.04 D (±0.94 D) with cyclopentolate (t = −5.38, p < 0.0001; all two-sided paired t-tests). There were no serious adverse reactions with either agent, although one infant temporarily developed redder than normal cheeks after instillation of cyclopentolate.
Our results suggest that tropicamide is as effective as cyclopentolate for the measurement of refractive error in most healthy, nonstrabismic infants.