Accommodative response/stimulus by dynamic retinoscopy: near add guidelines.

PURPOSE: Monocular estimation method (MEM) dynamic retinoscopy and low neutral (LN) dynamic retinoscopy are common procedures for evaluating the need for near-point plus adds for improved near-point performance in non-presbyopes. A combination of MEM and LN has been suggested to be a method of plotting accommodative response/accommodative stimulus functions and evaluating guidelines for prescribing from MEM.

METHODS: Using a combined MEM-LN procedure, MEM was performed on 80 young adults at 40 cm, with distance correction and with plus adds in 0.25 D steps up to and including +2.00 D. Modified Thorington dissociated phorias were also performed with each of the plus adds. Subjects picked a preferred add, which subjectively made print easiest and most comfortable to read.

RESULTS: The mean preferred add was +0.58 D over the distance prescription. The add derived from subtracting 0.25 D from the lag of accommodation with distance correction averaged 0.10 D more plus than the preferred add. The add at which dynamic retinoscopy showed a "with" motion of 0.25 D averaged 0.54 more plus than the preferred add. The add at which dynamic retinoscopy showed a "with" motion of 0.50 D averaged 0.16 more plus than the preferred add.

CONCLUSIONS: Adds derived from subtracting 0.25 D from the lag with distance correction and from finding the add that yields 0.50 D of "with" motion compared favorably with the preferred adds on average, but the standard deviations of the differences were high. Those guidelines could be reasonable starting points for the prescription of near-point plus adds for non-presbyopes, but follow-up testing to confirm or adjust add power would be advisable in the clinical setting.