Efficacy of varying target size and varying distance on the amplitude of accommodation by using Donder's and Sheard's...

To compare the measurement of amplitude of accommodation (AOA) by various techniques and to assess the effect of varying target size and varying distance on the AOA using Donder's and Sheard's Method.

A prospective study was conducted among 100 students aged between 18 and 30 years who met the inclusion criteria. Subjects with best-corrected visual acuity 6/6 at near and distance were included in the study. A comprehensive eye examination of the patients was carried out. Then, assessment of the near point of accommodation with the Royal Air Force rule by giving targets of different font sizes (N8 and N10) was performed repeatedly over distance correction, and diopter reading was noted. Then minus lens technique at different distances (at 33 cm and at 40 cm) was used to assess the AOA. IBM-SPSS 22.0 was used for data analysis.

Out of a total of 100 participants, 49 (49%) were males and 51 (51%) were females, with a mean age of 20 ± 1.79 years. Donder's method showed the highest AOA compared to Sheard's method. It has been found that there was a clinically significant difference in the AOA with the two different letter sizes (N8 and N10) during the monocular measurement using Donder's method. Furthermore, a clinically significant difference was found between the AOA when measured monocularly as well as binocularly at two different distances (at 33 cm and 40 cm) using Sheard's method.

We have concluded that the highest AOA was measured using Donder's method, and the effect of varying letter size and varying target distance on AOA using Donder's and Sheard's method is clinically significant. It is very crucial to consider the standard target size and target distance during the measurement of AOA as varying target size and target distance could result in varying AOA which may lead to inappropriate diagnosis and management of the condition as well.