Clinical testing of accommodative facility: Part 1. A critical appraisal of the literature.

Background: Accommodative facility testing is used in clinical care to assess functioning of the ocular accommodative system. The current clinical standard (binocular assessment using ±2.00 D lenses at 40 cm with a vectographic suppression check) was first described nearly 20 years ago as part of the last comprehensive review of the literature. The standard accommodative facility test imposes a variable requirement on patients of different ages who have a wide range of accommodative amplitudes. Method: In this article, we critically review the present body of literature on accommodative facility testing, with emphasis on the relation between symptoms, accommodative amplitude, and the results found during accommodative facility testing. Result: We include discussion of the five broad categories of accommodative facility studies: (1) recommendations for testing criteria; (2) normative data investigations; (3) reliability and variability assessment; (41 relation between accommodative facility and symptoms; and (5) other relationships (e.g., effect of test parameters on accommodative facility). Conclusion: Given the substantial variation in demand when testing patients of different ages (amplitudes). it is not surprising that a significant variation in responses has been reported in the clinical accommodative facility literature. Future clinical investigation of accommodative facility would benefit from a systematic investigation into the relationship between age and amplitude. The presence or absence of symptoms needs to be considered so that results of testing can be analyzed in relation to the severity of binocular vision-related symptoms.