Wright K W
Department of Pediatric Ophthalmology and Strabismus, Cleveland Clinic Foundation, Ohio, USA.
J Pediatr Ophthalmol Strabismus. 1996 May-Jun;33(3):153-5. doi: 10.3928/0191-3913-19960501-06.
Monocular optokinetic nystagmus (OKN) asymmetry is associated with disruption of early binocular visual development.
Three groups of treated esotropic patients and a group of normal controls were evaluated for the presence of clinically detectable monocular OKN asymmetry. Clinical assessment of monocular OKN asymmetry was performed by observing eye movements in response to a hand-held rotating drum. Asymmetry was quantitated on a scale of 0 to +3 OKN asymmetry. Clinical OKN asymmetry was evaluated in the following groups of patients: those with congenital esotropia treated with very early surgery achieving high-grade stereo acuity (group 1); those with congenital esotropia treated with late surgery achieving no stereopsis (group 2); those with acquired esotropia achieving high-grade stereo acuity after treatment with spectacle correction (group 3); and normal controls (group 4).
Two of the three patients in group 1 showed +3 OKN asymmetry despite having high-grade stereo acuity; the third one, who was surgically aligned earliest (13 weeks), demonstrated +1 OKN asymmetry. This patient achieved orthotropia, 40 seconds stereo acuity, perfect Randot stereo acuity, and had no dissociated vertical deviation or latent nystagmus. All 10 patients in group 2 (those with late alignment-after 1 year-and no stereo acuity) showed +3 OKN asymmetry. All four patients in group 3 (those with acquired hypermetropic esotropia and high-grade stereo acuity after treatment) and all 10 patients in the normal control group showed no OKN asymmetry.
Clinically obvious monocular OKN asymmetry can occur in patients with congenital esotropia who are aligned early and develop high-grade stereo acuity. Even brief periods of strabismus during the early period of binocular motor development can result in persistent OKN asymmetry. This suggests that binocular motor processing may develop distinct from, and prior to, the development of high-grade stereo acuity. OKN asymmetry appears to be a clinical sign of an insult to early binocular motor development.
单眼视动性眼球震颤（OKN）不对称与早期双眼视觉发育障碍有关。
对三组接受治疗的内斜视患者和一组正常对照者进行临床可检测到的单眼OKN不对称情况评估。通过观察对手持旋转鼓的眼球运动来进行单眼OKN不对称的临床评估。不对称程度按0至+3的OKN不对称量表进行量化。在以下几组患者中评估临床OKN不对称情况：先天性内斜视患者早期接受手术并获得高等级立体视锐度（第1组）；先天性内斜视患者晚期接受手术且未获得立体视（第2组）；后天性内斜视患者经眼镜矫正治疗后获得高等级立体视锐度（第3组）；以及正常对照者（第4组）。
第1组的三名患者中有两名尽管有高等级立体视锐度，但仍表现出+3的OKN不对称；第三名患者手术矫正最早（13周），表现出+1的OKN不对称。该患者实现了正位，有40秒的立体视锐度，完美的兰多立体视锐度，且无分离性垂直偏斜或潜在眼球震颤。第2组的所有10名患者（晚期矫正 - 1年后 - 且无立体视锐度）均表现出+3的OKN不对称。第3组的所有四名患者（后天性远视性内斜视且治疗后有高等级立体视锐度）和正常对照组的所有10名患者均未表现出OKN不对称。
早期矫正并获得高等级立体视锐度的先天性内斜视患者可能出现临床上明显的单眼OKN不对称。即使在双眼运动发育早期有短暂的斜视期也可能导致持续性OKN不对称。这表明双眼运动处理可能在高等级立体视锐度发育之前且与之不同地发展。OKN不对称似乎是早期双眼运动发育受损的临床标志。
