Subjective and objective measurement of human accommodative amplitude

Abstract

Purpose: To assess objective and subjective methods to measure accommodation in a young human population.

Setting: Research laboratory, University of Houston, College of Optometry, Houston, Texas, USA.

Methods: Accommodation was measured in the right eye of 15 young subjects (9 women and 6 men) whose ages ranged from 23 to 28 years and 1 36-year-old subject. The mean age of all subjects was 26 years. Accommodation was stimulated and measured with 4 techniques. Two subjective measures (focometer and minus-lens procedures) were used. Accommodation was also stimulated with minus-lens-induced blur and with pilocarpine 6% and measured objectively with a Hartinger coincidence refractometer.

Results: Accommodative amplitudes measured with the 2 subjective methods agreed with each other but differed from the objectively measured amplitudes. Objectively measured accommodative amplitudes were similar in all subjects, with a mean of about 7.0 diopters. Accommodation stimulated with pilocarpine reached a maximum 33 minutes after administration. Individuals with light irides showed a stronger accommodative response to pilocarpine than subjects with dark irides.

Conclusions: Subjective measures of accommodation tend to overestimate true accommodative amplitude. Methods exist to measure accommodation objectively. These include stimulating accommodation with trial lenses or pilocarpine 6% and measuring the accommodative response with an objective optometer such as a Hartinger coincidence refractometer. Objective measures of accommodation should be used to determine whether accommodation can be restored in presbyopes.