Facility of accommodation in myopia.
OBJECTIVE
Myopes have been shown to have abnormal accommodative characteristics. This study investigated the characteristics of accommodation facility in myopic and emmetropic students.


METHODS
Distance and near positive and negative accommodation response time components of facility were measured over a 1 min period using a -2.00 D/zero lens pair for distance responses and a +/-2.00 D lens pair for near responses. 79 students (37 myopes and 42 emmetropes) aged 18-27 years acted as subjects. Subjects were masked, and the results were analysed in a masked fashion.


RESULTS
Mean distance facility was significantly lower (9.7 cycles per minute (cpm)) in the myopic group compared with the mean distance facility in the emmetropic group (15.6 cpm; p < 0.005). There was no significant difference in the near facilities of the two groups (11.5 cpm in myopes vs 12.9 cpm in emmetropes). Positive accommodation response time for distance vision was greater than 4 s in 45% of myopes and in 9% of emmetropes.


CONCLUSIONS
Our findings confirm that myopes tend to have abnormal accommodation responses to blur. Distance facility, but not near facility of accommodation is more frequently reduced in myopes than in emmetropes.
O'Leary
D J
DJ
Department of Optometry and Ophthalmic Dispensing, Anglia Polytechnic University, Cambridge, UK. D.O'leary@anglia.ac.uk
Allen
P M
PM
D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D006801:Humans; D009216:Myopia / Q000503:physiopathology*; D011930:Reaction Time; D014792:Visual Acuity / Q000502:physiology