[Pathogenesis and treatment of accommodative disturbance].
Using a computer-assisted infrared optometer with a pupillograph, we tried to obtain basic understanding of accommodative disturbance and its by investigating tonic (dark focus) level of accommodation and quasi-static accommodative response. In normal volunteers in whom either visual fatigue, general fatigue, or drunkeness was loaded intentionally, myopic shift of refraction, increased refractive fluctuation, and miosis were induced in all cases but the effect on amplitude of accommodative response was minimal. Subjects that worked at a computer terminal all day for 2 years, but not controls, developed myopic change at a statistically significant level. The effect on tonic level of accommodation of subject age, sustained near-vision tasks, and topical application of autonomic-related drugs was investigated. In subjects with severe eyestrain, myopic shift of tonic accommodation and prominent pupillary unrest were observed, suggesting increased parasympathetic excitation. One patient who was accidentally exposed to diisopropyl fluorophosphate, a potent cholinesterase inhibitor, showed a phenomenon similar to that mentioned above. Chaos attractors based upon the Shil'nikov phenomenon were introduced for evaluation of microfluctuation and pupillary unrest, as first applied by Sumida et al. Topical application of low-dose cyclopentolate hydrochloride was effective for treating accommodative abnormality in professional computed workers, who sometimes develop abnormal parasympathetic excitation. Based on quasi-static accommodation measurements, accommodative abnormality after head and neck injury, including whiplash injury, was divided into two completely different states: accommodative spasm and palsy. Since quasi-static accommodation was greatly affected by satellite ganglion block, sympathetic innervation from cervical ganglions may strongly influence accommodative response. Hyperthyroidism, which may be accompanied by sympathetic hyper-excitation, showed diminished accommodative response. In patients after refractive surgery by excimer laser, there was no difference in accommodative response before and after surgery, although tonic accommodation was slightly unstable after surgery. These findings suggest that the evaluation of tonic level or a similar state of accommodation and pupillary unrest will yield extremely valuable information in regard to various accommodative disturbances.
Department of Ophthalmology, Kyoto Prefectural University of Medicine, Japan.
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Kinoshita
D000065:Accommodation, Ocular; D000293:Adolescent; D000328:Adult; D001248:Asthenopia / Q000188:drug therapy / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000188:drug therapy / Q000209:etiology; D011446:Prospective Studies; D014786:Vision Disorders / Q000188:drug therapy / Q000503:physiopathology*