RESUMO
Aim: To investigate the changes in near accommodative facility and response time in young adults following computer work of 30 minutes and 1 hour in duration. Methods: A total of 50 young adults (37 females, 13 males) with mean age of 20.68 ± 1.33 years were included in this experimental study. Monocular near accommodative facility was measured using ±2.00 Dioptre Sphere (DS) flipper at 40 cm using the N6 (the smallest print size that can be read by an individual with normal visual acuity) target before and after two reading tasks. Both pre- and post-task measurements were video recorded using a smart phone and the number of cycles per minute, positive response time (time taken to stimulate accommodation), and negative response time (time taken to relax accommodation) were calculated from the video recording. Data were analysed using SPSS Version 22.0. Results: Out of the 50 participants, 29 were emmetropes (Mean SER: 0.16 ± 0.29 D), and 21 were myopes (Mean SER: -1.89 ± 1.16 D). The mean pre-task accommodative facility was 6.79 ± 3.52 cycles per minute, and the post-task accommodative facility was 6.25 ± 3.65 cycles per minute (p = 0.10) for the 30-minutes task and 5.76 ± 3.89 cycles per minute (p = 0.01) for 1-hour task. The mean pre-task positive response time was 2.87 ± 1.55 seconds, and the post-task positive response times for 30 minutes and 1 hour were 2.86 ± 1.67 seconds (p = 0.88) and 2.98 ± 2.33 seconds (p = 0.42), respectively. The mean pre-task negative response time was 8.77 ± 8.83 seconds, and the post-task negative response times for 30 minutes and 1 hour task were 11.83 ± 14.28 seconds (p = 0.16) and 14.72 ± 17.32 seconds (p = 0.03), respectively. Conclusion: Monocular near accommodative facility was significantly reduced, and negative response time was delayed following 1 hour of computer work.
RESUMO
Background: Accommodative functions are known to differ between myopes and emmetropes. It is not known whether accommodative facility differs at near between younger adolescent and older adolescent myopes and emmetropes. Aim: To examine whether accommodative facility differs at near between younger and older adolescent myopes and emmetropes. Methods: 119 participants aged between 11-21 years were recruited. Refractive error was measured using cycloplegic retinoscopy. Near monocular accommodative facility was measured for 60 seconds, using a +2.00D/-2.00D handheld flipper and N6 print at 40 cm. Participants were classified into two age groups: (i) younger adolescents (range: 11-14 years) and (ii) older adolescents (range: 15-21 years). The criterion applied to define myopia was spherical equivalent refraction: ≥-0.50D) and spherical equivalent refraction: -0.25D to +0.75D) for emmetropia. Univariate Analysis of Variance was carried out to analyze the interaction of age groups and refractive groups on near accommodative facility. Results: Near monocular accommodative facility was significantly lower (p = 0.003) in younger adolescents (5.87 ± 3.72 cpm) compared to older adolescents (8.11 ± 4.11 cpm), indicating age as a significant main effect (F1,115 = 13.44; p = 0.0001). Younger adolescent emmetropes (4.77 ± 2.05 cpm, p = 0.005) and younger adolescent myopes (6.48 ± 4.12 cpm, p = 0.022) had significantly lower monocular near accommodative facility compared to older adolescent emmetropes (9.52 ± 3.27 cpm), but did not show any difference when compared to older adolescent myopes (p > 0.05). This indicates a significant association linking age and refractive error to near accommodative facility (F1,115 = 4.60; p = 0.03). Conclusion: Younger adolescent myopes and younger adolescent emmetropes had reduced monocular near accommodative facility than older adolescent emmetropes, but not when compared to older adolescent myopes.