Abstract
Purpose: :
To measure accommodative response (AR) in a wide age range population by means of a double-pass system.
Methods: :
84 patients were enrolled in this study, with a mean age (± SD [range]) of 34.55 ± 12.04 years (15 to 55 years), a mean subjective manifest spherical refraction of -0.99 ± 1.72 D (-8.00 to +3.00 D), a mean subjective astigmatic refraction of -0.46 ± 0.46 D (0 to -1.75 D) and a mean best corrected visual acuity of 1.13 ± 0.10 (0.9 to 1.2). Patients were corrected according to their subjective manifest refraction, had monocular vision and were instructed to focus on a fixation test during measurements. Accommodation was stimulated from 0 to 5 D using a push-up method, in steps of 1 D. Accommodation was measured with an open field double-pass system aiming at the best double-pass image, whose vergence was then associated with the AR value.
Results: :
Patients were divided in four groups of different ages in order to perform the comparison: from 15 to 25 years, n = 24; from 26 to 35 years, n = 20; from 36 to 45 years, n = 20; and from 46 to 55 years, n = 20. As expected, we found that the AR decreased with age, with a noticeable fall in patients older than 35 years. We found higher AR than those previously reported by other authors using different techniques for the two younger groups. For example with a 5 D accommodative stimulation we found a mean AR of 4.93 ± 0.41 D for the 15 to 25 years group and of 4.52 ± 0.65 D for the 26 to 35 years group. The AR measured in the 36 to 45 years group was significantly lower and with a much higher dispersion; with 5D accommodative stimulation AR was 3.09 ± 1.22 D. The oldest group (46 to 55 years) reported lower results than those found in the literature, with a mean value of 1.01 ± 0.31 D when stimulating 5D.
Conclusions: :
We have assessed the AR in a wide age range population based on the retinal image quality measured with an open-field double-pass system. The measured AR was very high in young patients, decreased significantly in patients older than 35 years old and was very low in the oldest group. The differences with results available in the literature, which were obtained using other techniques, could probably be attributed to the fact that our measures are based on retinal image quality and are therefore not affected by pseudoaccomodation.
Keywords: accommodation • aberrations • depth