Manifest latent and congenital nystagmus waveforms in the same subject - A need to reconsider the underlying mechanisms of nystagmus

被引:10
作者
Abadi, RV [1 ]
Scallan, C [1 ]
机构
[1] Univ Manchester, Inst Sci & Technol, Dept Optometry & Vis Sci, Manchester M60 1QD, Lancs, England
关键词
congenital nystagmus; manifest latent nystagmus; visual feedback; extended slow phase; neural integrator;
D O I
10.1076/noph.21.4.211.3890
中图分类号
R74 [神经病学与精神病学];
学科分类号
摘要
We report a unique case of a horizontal manifest latent nystagmus (MLN) that is converted to a congenital nystagmus (CN) on covering the subject's only seeing eye. The subject is a 65-year-old female who, at five days after birth, had her right eye ennucleated, A prosthetic eye was fitted soon after. Horizontal eye movements were recorded using an IRIS (Skalar Medical) infrared system. The effect of visual feedback on primary and secondary gaze, smooth pursuit, opto-kinetic responses, and the role of selective attention on fixation stability were examined. On primary gaze with the left eye open and under normal viewing conditions, the patient exhibited a typical MLN wave form. The slow phase was a decreasing velocity acid the fast phase beat to the left. On covering the left eye, the nystagmus slow phase immediately increased in velocity and the fast phase beat to the right. Removal of visual feedback (darkness or stabilising the retinal image) also brought about a change from MLN to CN. Both the MLN and CN states were strongly influenced by gaze. The decreasing velocity MLN slow phase was also seen to change to a grossly extended slow phase during periods of visual disengagement, On occasions, these oscillations became a short burst of right-beating CN whenever the patient lost interest in the visual task. This is the first report of an adult subject who can;exhibit either of two separate and sustained nystagmus states, an MLN or a CN, whenever the only eye is covered. Two explanations are offered to account for the presence of the two separate waveforms, Central to our interpretation is that the neural integrator has an eccentric null and that it is under a variable gain control. Furthermore, we propose that future models of nystagmus generation will need to include retinal image and attention control loops.
引用
收藏
页码:211 / 221
页数:11
相关论文
共 23 条
[1]  
ABADI RV, 1986, DOC OPHTHALMOL, V64, P153, DOI 10.1007/BF00159990
[2]   THE INFLUENCE OF PREEXISTING OSCILLATIONS ON THE BINOCULAR OPTOKINETIC RESPONSE [J].
ABADI, RV ;
DICKINSON, CM .
ANNALS OF NEUROLOGY, 1985, 17 (06) :578-586
[3]  
[Anonymous], [No title captured]
[4]  
Dell'Osso L. F., 1981, MODELS OCULOMOTOR BE, P233
[5]  
DELLOSSO LF, 1987, INVEST OPHTH VIS SCI, V28, P1873
[6]  
DELLOSSO LF, 1979, ARCH OPHTHALMOL-CHIC, V97, P1877
[7]  
DELLOSSO LF, 1985, JPN J OPHTHALMOL, V29, P351
[8]   EVALUATION OF SMOOTH PURSUIT IN THE PRESENCE OF CONGENITAL NYSTAGMUS [J].
DELLOSSO, LF .
NEURO-OPHTHALMOLOGY, 1986, 6 (06) :383-406
[9]   FOVEATION DYNAMICS IN CONGENITAL NYSTAGMUS .2. SMOOTH PURSUIT [J].
DELLOSSO, LF ;
VANDERSTEEN, J ;
STEINMAN, RM ;
COLLEWIJN, H .
DOCUMENTA OPHTHALMOLOGICA, 1992, 79 (01) :25-49
[10]  
DELLOSSO LF, 1993, CONGENITAL TYPES INF, P229