Abstract
Purpose:
Addition lenses may play a role in the retardation of the progression of myopia. The purpose of this study was to evaluate the changes to accommodation and phoria when myopic children perform near work with different near addition lenses.
Methods:
We measured accommodative response and phoria in 18 children (14 myopic and 4 emmetropic) at 33cm through their distance refractive correction alone or this correction combined with multiple addition lenses (+0.50D, +1.00D, +1.50D, +2.00D, +2.50D, and +3.00D). Accommodative response was measured using the infrared optometer (WAM-5500) and near phoria was measured using the modified Thorington technique.
Results:
Myopic children had larger lags (1.35D) than emmetropic children (0.86D) for a 33 cm reading target through the distance correction, and significantly decreasing lags of accommodation with larger addition lenses (P<0.01). A small lead of accommodation (0.22D) was found with the addition of +3.0D lens . There were obvious differences in the mean responses between the two refractive groups across the multiple addition lenses (F=28.74, P<0.01). The near phoria showed significant increases towards exophoria in both groups with larger addition lenses during reading (P<0.01).
Conclusions:
Near addition lenses may actually decrease the degree of retinal defocus for myopic children who have large lag. Accommodative lead to a +3.0D lens defocus to a near target (33cm) may be associated with proximal accommodation.
Keywords: 404 accommodation •
605 myopia