Abstract
Purpose: :
To determine the influence of peripheral defocus on lag of accommodation and its fluctuation.
Methods: :
Accommodation was measured continuously at 5 Hz in 10 Chinese young adults by means of an open field infrared autorefractor (Grand Seiko Autorefractor / Keratometer WAM-5500, Grand Seiko Co. Ltd., Hiroshima, Japan). Subjects were reading a Chinese text character by character at 2Hz on a LCD screen at 33 cm while wearing ophthalmic lenses (Plano, -2.00D, +4.00D, -4.00D) with a central 8 mm hole. Lens order was randomized. 10 seconds of measurements were used for analysis for each lens. Measurements were repeated 3 times during a single session.
Results: :
Lags of accommodation were 0.80 ± 0.10D, 0.72 ± 0.09D, 0.79 ± 0.09D, 0.76 ± 0.10D and intra-individual standard deviations of accommodation 0.18 ± 0.02D, 0.15 ± 0.01D, 0.16 ± 0.01D, 0.16 ± 0.01D respectively for Plano, -2.00D, +4.00D, -4.00D lenses. Lens type did not have any influence on lag of accommodation (p=0.20) or on its fluctuation (p=0.29).
Conclusions: :
Peripheral defocus had no short time influence on lag of accommodation or its fluctuation. These findings seem to confirm that the effect of peripheral defocus on emmetropization is a local retinal phenomenon rather than a consequence of an increased lag of accommodation.
Keywords: accommodation • myopia