Purpose: School children with myopia were trained using a visual stimulation device that generated an isolated blur stimulus on a visual target, with a constant retinal image size and constant brightness. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and papillary reaction were measured to investigate the effectiveness of the training.
Subjects and methods: There were 45 school children with myopia without any other ophthalmic diseases. The mean age of the children was 8.9±2.0 years (age range; 6-16) and the mean refraction was -1.56±0.58 D (mean±standard deviation). As a visual stimulus, a white ring on a black background with a constant ratio of visual target size to retinal image size, irrespective of the distance, was displayed on a liquid crystal display (LCD), and the LCD was quickly moved from a proximal to a distal position to produce an isolated blur stimulus. Training with this visual stimulus was carried out in the relaxation phase of accommodation. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and pupillary reaction were investigated before training and every 3 months during the training.
Results: Of the 45 subjects, 42 (93%) could be trained for 3 consecutive months, 33 (73%) for 6 months, 23 (51%) for 9 months, and 21 (47%) for 12 months. The mean refraction decreased by 0.83±0.56 D (mean±standard deviation) and the mean axial length increased by 0.47±0.16 mm at 1 year, showing that the training bad some effect in improving the visual acuity. In the tests of the dynamic accommodative responses, the latency of the accommodative-phase decreased from 0.4±0.2 sec to 0.3±0.1 sec at 1 year, the gain of the accommodative-phase improved from 69.0±27.0% to 93.3±13.4%, the maximum speed of the accommodative-phase increased from 5.1±2.2 D/sec to 6.8±2.2 D/sec and the gain of the relaxation-phase significantly improved from 52.1±26.0% to 72.7±13.7% (corresponding t-test, p<0.005). No significant changes were observed in the pupillary reaction.
Conclusion: The training device was useful for improving the accommodative functions and accommodative excess, suggesting that it may be able to suppress the progression of low myopia, development of which is known to be strongly influenced by environmental factors.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 116: 929-936, 2012.