Kemp C M, Jacobson S G, Faulkner D J, Walt R W
Department of Visual Science, Institute of Ophthalmology, London, England.
Exp Eye Res. 1988 Feb;46(2):185-97. doi: 10.1016/s0014-4835(88)80076-9.
Details of rod and cone dysfunction in vitamin A deficiency have been studied in two subjects with primary biliary cirrhosis and one with Crohn's disease, all of whom presented with symptoms of night blindness. Visual function in the mid-peripheral retina was monitored with two-color adaptometry and rhodopsin levels were measured by fundus reflectometry. Initially all three subjects had no measurable rod function and delayed cone adaptation. In one case the dark-adapted cone threshold was also elevated. Oral supplementation with vitamin A restored visual function to normal within 8 days in all subjects. During supplementation, cone function was restored more rapidly than that of rods, though the pattern of recovery was similar for each receptor type. Final thresholds improved first, though the rates at which they were reached were abnormally slow. As recovery continued, adaptation kinetics returned to normal. When rod adaptation was delayed, the regeneration of rhodopsin was also abnormally slow. When rod final threshold was 2 log units higher than normal, rhodopsin regeneration was incomplete, reaching about 70% of the normal level. The initial stages of visual dysfunction during onset of vitamin A deficiency were studied in one subject, and were found to mirror the pattern seen during recovery: rod adaptation was initially slower than normal, but reached completion. Cone adaptation remained normal until rod function was almost absent.
对两名原发性胆汁性肝硬化患者和一名克罗恩病患者的维生素A缺乏所致视杆和视锥功能障碍细节进行了研究，所有患者均有夜盲症状。采用双色自适应验光法监测中周边视网膜的视觉功能，并用眼底反射ometry测量视紫红质水平。最初，所有三名患者均无可测量的视杆功能且视锥适应延迟。在一例中，暗适应视锥阈值也升高。所有患者口服补充维生素A后8天内视觉功能恢复正常。补充期间，视锥功能恢复比视杆功能更快，不过每种受体类型的恢复模式相似。最终阈值首先改善，但其达到正常的速度异常缓慢。随着恢复的持续，适应动力学恢复正常。当视杆适应延迟时，视紫红质的再生也异常缓慢。当视杆最终阈值比正常高2个对数单位时，视紫红质再生不完全，达到正常水平的约70%。对一名患者维生素A缺乏发作期间视觉功能障碍的初始阶段进行了研究，发现其与恢复期间所见模式相似：视杆适应最初比正常慢，但最终完成。视锥适应保持正常，直到视杆功能几乎丧失。
