PURPOSE. Accommodation is a change in dioptric power of the eye which declines from childhood to 0 D by about age 55 with the progression of presbyopia. Accommodation is routinely measured clinically with the subjective push-up test, which does not unequivocally demonstrate the presence of accommodation. New surgical techniques are aimed at restoring accommodation in presbyopes and results are tested with the push-up test. However, objective tests are necessary to demonstrate if accommodation truly occurs. Several objective and subjective methods to assess accommodative amplitude, previously tested in young subjects, have now been tested in normal older subjects to understand the efficacy of these methods to measure accommodation in a pre-presbyopic and presbyopic population. METHOD. To date 23 subjects, age 31-53 (mean age 43.7), have been tested. Accommodative amplitude was first measured monocularly using three subjective measurements; 1) the push-up test, 2) minus lenses to blur and 3) a Focometer (In FOCUS, Houston). Amplitude of accommodation was then measured objectively using a Hartinger Coincidence Refractometer (Zeiss, Germany) when accommodation was stimulated monocularly in two ways; 1) minus lenses to blur and 2) topical instillation of 6% pilocarpine.
RESULTS. Results on this older population were qualitatively similar to the results reported previously in a younger population. The push-up test overestimated accommodative amplitude in 21 of 23 subjects. Two related subjective methods, the minus lenses to blur and the Focometer, produced comparable results, underestimating the objectively measured accommodative amplitude in the younger and overestimating it in the older subjects. Results found for the two methods in which accommodation was stimulated and measured objectively with the Hartinger were comparable to each other. When accommodation was observed, 6% pilocarpine produced stronger responses in subjects with light irides.
CONCLUSIONS. These results suggest that objective measurement of accommodative amplitude using the Hartinger is a more accurate measurement of true accommodative ability compared to all of the subjective methods tested, especially for the presbyopes. In presbyopes, subjective tests overestimate true accommodative amplitude by up to 4 D. This overestimation can be minimized by using the objective methods to stimulate and measure accommodation.