|Title||The objective measurement of accommodative response by the use of video targets|
|Author, Co-Author||Zhang Ning, Carly Lam, Long Qian Liu, Xiao Ming Chen, Shahina Pardhan|
Purpose: To validate a new method for measuring accommodative response (AR) using video animation and visual targets that is suitable for subjects with attentional or intellectual problems.
Methods: Subjects with no ocular abnormalities and LogMAR visual acuity (BCVA) of 1.0 or better were recruited. AR was measured by using WAM-5500 (Grand Seiko, Japan) at distances of 20cm, 25cm, 33.3cm 40cm and 50cm using the conventional method in which subjects fixated on a 1.0 (LogMAR) letter on the near-point chart. The AR was measured again with an animated video clip in which a N5 size number was flashed for 5 seconds within a video display lasting 10 seconds. Subjects were asked to report when they saw the number to ensure that they maintained their concentration when watching the video. The video clip was played on an iPod, which was mounted on a rod, which moved in front of the autorefractor. The accommodation stimuli-responses were then compared with those tested with the near-point chart.
Results: 31 young subjects, aged 20 to 28 years participated in the study. There were no significant differences of accommodation stimuli-response between these two methods (p > 0.05). The Bland-Altman plots of the mean difference and 95% limits of agreement for the 2D, 2.5D, 3D, 4D and 5D stimuli were: 0.04D (p = 0.80), from -0.53 to 0.62D; 0.10D (p = 0.78), -0.73 to 0.52D; -0.03D (p = 0.07), from -0.67 to 0.60D; -0.12D (p = 0.17), from -0.81 to 0.57D; -0.05D(p = 0.10), from -1.00 to 0.90D.
Conclusion: There is a good agreement in the measured accommodative responses between the video target and the traditional methods. The novel video target method is a suitable method for measuring AR in subjects with attentional or intellectual deficiencies.
|Affiliation of Co-Authors||School of Optometry, The Hong Kong Polytechnic University, Department of Ophthalmology, West China Hospital, Department of Ophthalmology, West China Hospital, Vision and Eye Research Unit (VERU), Anglia Ruskin Universit|