Familial Voluntary Nystagmus

Purpose: To examine the pathological significance and familial occurrence of voluntary nystagmus. Patients and Methods: We examined two families orthoptically as well as with video and search-coil techniques or electronystagmography (ENG). Three members of three generations of the first family and a 9-year-old boy from a second family not related to the first were able to generate a voluntary horizontal nystagmus. Results: The characteristics of the nystagmus of our original patient, his daughter and 8-year-old grandson (1st family) were remarkably similar: duration of 2–5 seconds, amplitudes of 1–4° and frequencies around 15 cycles/second. In the second family, our patient with a congenital esotropia and hyperopia was the only one of his family who could voluntarily produce a nystagmus of about 5° and 10 cycles/second for maximum of 20 seconds. During prolonged reading, the same nystagmus with disturbing oscillopsia developed involuntarily and was not suppressible. We added +0.75 diopters to both lenses of his spectacles to account for the result of our cycloplegic refraction. This stopped the involuntary nystagmus during near fixation. Discussion: To avoid unintentional “bouts” of voluntary nystagmus, a reduction of the convergence impulse by plus-lenses may be effective. The parameters of voluntary nystagmus can be considered family-specific.     

The treatment of congenital idiopathic nystagmus by intermittent photic stimulation

An analysis is presented of the results obtained by treating 54 patients with congenital nystagmus using intermittent photic stimulation. The major beneficial effect has been to improve the visual acuity, though the nystagmus itself is sometimes reduced in amplitude or even eliminated; an unexpected bonus, in certain cases, is the improvement in stereoscopic acuity.     

Recognizing periodic alternating nystagmus

Congenital or acquired periodic alternating nystagmus (PAN) is characterized by nystagmus occurring in a cycle. The cycle consists of a left-beating nystagmus, a transition phase, a right-beating nystagmus, and a further transition phase. The purpose of this review is to assist the clinician in the recognition of periodic alternating nystagmus (PAN), either as a type of congenital nystagmus or in its acquired form, and to highlight why such identification is important. Recent studies using eye movement recordings 1–3 are reviewed to point out the frequency of congenital PAN in samples of patients with congenital nystagmus, and to describe the characteristics of the waveforms and the influence of foveation time on the alternation of head turns. Classical and new surgical alternatives are reported. The identification of congenital PAN is essential when surgical treatment is being considered for the correction of anomalous head postures. Acquired PAN is usually due to cerebellar disease and causes oscillopsia. 4–10 Unlike other forms of acquired nystagmus, it responds well to drug treatment.     

Disorders of vertical optokinetic nystagmus in patients with ocular misalignment

PURPOSE: To compare responses to vertical and horizontal optokinetic (OK) stimulation in patients with disorders of ocular alignment. METHODS: Using the magnetic search coil technique, we measured horizontal and vertical rotations of both eyes in six patients with strabismus since childhood and eight normal subjects. The OK stimulus subtended 72 degrees horizontally and 60 degrees vertically, consisted of black-and-white stripes with a spatial frequency of 0.04 cycles/degree, and moved either vertically or horizontally at 22.5 or 12 degrees/s. All patients and controls were tested with both eyes viewing and monocularly. RESULTS: Vertical OK responses were asymmetric in most normals and patients. The direction of this asymmetry varied between individuals, but upward stimuli more commonly elicited a greater response than downward stimuli. Monocular horizontal OK responses were symmetric in normals; patients showed either an asymmetry with greater responses for nasal motion, or a directional bias. During monocular and binocular viewing, vertical OK stimulation induced vertical nystagmus in normal subjects, but all patients showed diagonal responses, with horizontal components that were significantly greater than controls. The inappropriate horizontal component of the response increased at the higher stimulus speed, and was not simply due to latent nystagmus. CONCLUSIONS: Patients with disorders of ocular alignment since childhood show an inappropriate horizontal response to vertical OK stimuli, indicating directional abnormality of either motion vision pathways or the ocular motor response.     

Vergence nystagmus induced by motion in the ground plane: normal response characteristics

We displayed backward/forward motion on a computer monitor in the ground plane. Subjects looked at the center of a moving pattern and eye movements of both eyes were recorded with a search coil system. Involuntary nystagmus including vertical version (VV) and horizontal vergence (HV) was recorded. Dynamics of the nystagmus showed that the slow and quick phase of VV and HV were always associated with each other while the monocular horizontal eye movements composed of HV were either symmetrical or asymmetrical. Peak velocity, amplitudes and frequency of the VV and HV responses were quantified. The results suggest that involuntary HV nystagmus can be induced by simple motion from simulated optic flow in the ground plane and the HV nystagmus helps moving subjects to stabilize their gazes on the object of interest.     

The efficiency of the central and peripheral retina in driving human optokinetic nystagmus

Previous experiments to decide whether the gain of optokinetic nystagmus (OKN) is increased or decreased by occlusion of the central retina involved the use of stationary edges on the occluder and unmatched contrasts. With these factors controlled, it was confirmed that OKN gain is severely reduced by occlusion of the central retina but only at stimulus velocities above about 30°/sec. The gain of horizontal OKN was found not to increase with increasing width of the display if the lateral edges are blurred. The high gain of centrally driven OKN may be related to the ability of higher mammals to stabilize the images of objects at a given distance in a complex parallactic visual field.     

Asymmetries of optokinetic nystagmus in amblyopia: the effect of selected retinal stimulation

Open loop optokinetic eye movements were measured in response to monocular nasalward and temporalward visual field movement presented at four selected retinal sites in 6 strabismic amblyopes and 4 normal observers. Stimulus sites included the central retina (10 X 10 deg), a large field (40 X 32 deg), a large peripheral field with the center (10 X 10 deg) blocked out and a hemiretinal field (15 X 32 deg) excluding the fovea. We found directional preferences of OKN in amblyopia to nasalward stimulus movement for the foveal and concentric peripheral stimuli. The results of peripheral hemiretinal optokinetic stimulation of amblyopic subjects revealed a deficient OKN slow phase response from the temporal hemiretina, particularly for temporalward stimulus movement. There was no marked asymmetry of OKN in the normal group for the concentric stimuli. A normal preference was found for nasalward and temporalward stimulus field movement imaged on the nasal and temporal hemiretinae respectively. These results are interpreted in terms of a model of cortical and subcortical pathways for OKN derived from comparative studies of cat and monkey.     

Influence of slow eye movements and nystagmus on pattern induced visual evoked potentials

The authors checked the effect of pursuit and combined slow and fast eye movements on the VEP in normal subjects. The results were compared with those in patients showing a horizontal nystagmus of various origin. The main effect of slow and nystagmic eye movements on VEP was a reduction of P2 amplitude without significant shift of P2 latency. It is concluded that the main reason for decreased VEP responses is the decrease of visual contrast due to retinal blurring. In patients with nystagmus, stimulus patterns should be used that match the respective plane of eye rotation.     

Scanning the Ocular Albinism 1 (OA1) Gene for Polymorphisms in Congenital Nystagmus by DHPLC

Background: Nystagmus is common to all types of albinism. Some subjects with nystagmus lack convincing signs of albinism, have no other visual pathway disease, and are classified as possessing congenital idiopathic nystagmus (CN). It has been postulated that CN may be a form of ocular albinism. Methods: The presence of nystagmus, iris transillumination, and visual acuity were recorded in 39 CN and albino patients and their families. Physical characteristics were also noted. DNA from buccal swabs was obtained for use in denaturing high performance liquid chromatography (DHPLC) and chemical cleavage of mismatch (CCM) to scan several hotspots for X-linked ocular albinism (OA1) mutations. Results: Two previously reported polymorphisms were confirmed: neither was found to be a causative mutation. Conclusion: No correlation was identified between nystagmus and OA1.     

伴眼球震颤的中高度近视眼准分子激光原位角膜磨镶术的效果

目的 探讨应用准分子激光原位角膜磨镶术(LASIK)治疗伴有先天性眼球震颤的近视的疗效.方法 对14例(28眼)伴有眼球震颤的近视施行LASIK治疗,等效球镜度数在-5.00～-12.00 D之间,排除角膜炎症,圆锥角膜等眼科疾病.眼球震颤类型:14例均为水平冲动型眼球震颤,眼震值4～～8 mm,震颤频率2～3次/s,其中轻度代偿头位10例,明显代偿头位4例.结果 术后眼球震颤幅度较术前变小,眼震值3～6 mm,震动频率1～2次/s;术后的裸眼视力与术前最佳矫正视力差异无统计学意义;术前的平均屈光度为(-5.21±0.48)D,术后1年为(-0.32±0.25)D.结论 LASIK治疗伴有眼球震颤的近视疗效确切,安全.     

Active blockage and rest position nystagmus: electromyographic demonstration of two types of ocular induced head-turn

A differentiation of two types of head-turns due to nystagmus, by means of electromyography (EMG) is demonstrated in this paper. The first type is represented by patients who actively block the nystagmus, by means of an increase of discharge of the extraocular muscles who are synergistic and responsible for the head-turn. This block has the same features of the block of nystagmus in covergence and usually exceeds 10–15° from the primary position. The second type is made out of patients whose head-turn is explained with the null-position of Kestenbaum. Here the nystagmus simply disappears in the position of head-turn, which usually is of no more than 10–15°. Both types of patients show the same electronystagmographic features in the position of head-turn. This differentiation is useful from the clinical standpoint. In fact, only the first type of head-turn may require, besides a classical Anderson or Kestenbaum procedure, also a posterior fixation suture according to Cuppers. This operation would be useless in the second type of head-turn. Clinical signs useful for differentiating these two types of head-turn are presented as well.     

用增加PARKS法手术治疗先天性运动缺陷型眼球震颤

目的手术治疗先天性运动缺陷型眼球震颤的代偿头位，以期矫正眼位和头位倾斜，消除眼震和提高视力。方法用增加Parks（5、6、7、8mm）法手术治疗指征为代偿头位≥30°者；头位30°时手术量增加40％，头位45°时手术量增加60％。结果9例平均随访18月。头位、眼震强度和视力均明显改善；残余头位均＜15°，全部治愈；眼震强度由术前平均37．34减少到术后平均3．40；视力增加2行以上者占83．3％。结论用增加Parks5、6、7、8mm）法手术治疗代偿头位≥30°的先天性运动缺陷型眼球震颤有显著疗效。     

用PARKS(5、6、7、8mm)法和增加PARKS法手术治疗先天性运动缺陷型眼球震颤

目的:手术方法治疗先天性运动缺陷型眼球震颤。方法:1987—1994年,我们用Parks(5、6、7、8mm)法和增加Parks法手术治疗19例,头位≥30°者手术量增加40％-60％。结果:19例病人,平均随访22个月。头位、眼震强度和视力均明显改善,头位由术前平均30.5°减少到术后平均4.9°;眼震强度由术前平均36.0减少到术后平均9.7;19例病人中的21眼(55.3％)Snellen视力增加2行以上。结论:用Parks(5、6、7、8mm)法和增加Parks手术治疗先天性运动缺陷型眼球震颤有显著疗效。眼科学报 1996;12:110—112。     

Clinical and Electrophysiological Effects of Extraocular Muscle Surgery on Patients with Infantile Nystagmus Syndrome (INS)

The purpose of this report is to summarize clinical and electrophysiological effects of extraocular muscle surgery in patients with INS. Our hypothesis is that surgery on the extraocular muscles of patients with INS changes their nystagmus resulting in improved vision and visual functions. All patients had all four virgin horizontal recti operated on, either for strabismus alone, nystagmus alone, for a head posture due to an eccentric null zone alone or for a head posture due to an eccentric null zone plus strabismus. All patients have been followed for at least 12 months. Subjective outcome measures include the pre- and post-operative binocular best optically corrected null zone acuity (NZA) in 75 patients and gaze dependent acuity (GDA) in 12 patients. Objective outcome measure included null zone width (NZW) in 75 patients. The results are summarized as follows: NZA increased. 1 LogMar or greater in 75% with those patients ≤8 years significantly better. Subjective GDA and NZW measured from eye movement recordings showed persistent, significant increases. This report adds to the evidence that surgery on the extraocular muscles in patients with INS has independent neurological and visual results, from simply reposition the head, eye(s) or visual axis.     

Optokinetic nystagmus in harbor seals (Phoca vitulina)

Harbor seals experience motion due to self-motion and to movement in the external world. However, motion vision has not been studied yet in marine mammals moving in the underwater world. To open up this research, optokinetic nystagmus (OKN) as a basic motion sensing and retinal image stabilizing reflex was studied in four harbor seals during stimulation with moving black-and-white stripe patterns. All seals responded with optokinetic eye movements. Detailed measurements obtained with one animal revealed a moderate gain for horizontal binocular OKN. Monocularly stimulated, the seal displayed a symmetrical OKN with slightly stronger responses to leftward moving stimuli, and, surprisingly, a symmetrical OKN was found in the vertical domain.     

Optokinetic nystagmus is elicited by curvilinear optic flow during high speed curve driving

When analyzing gaze behavior during curve driving, it is commonly accepted that gaze is mostly located in the vicinity of the tangent point, being the point where gaze direction tangents the curve inside edge. This approach neglects the fact that the tangent point is actually motionless only in the limit case when the trajectory precisely follows the curve’s geometry. In this study, we measured gaze behavior during curve driving, with the general hypothesis that gaze is not static, when exposed to a global optical flow due to self-motion. In order to study spatio-temporal aspects of gaze during curve driving, we used a driving simulator coupled to a gaze recording system. Ten participants drove seven runs on a track composed of eight curves of various radii (50, 100, 200 and 500 m), with each radius appearing in both right and left directions. Results showed that average gaze position was, as previously described, located in the vicinity of the tangent point. However, analysis also revealed the presence of a systematic optokinetic nystagmus (OKN) around the tangent point position. The OKN slow phase direction does not match the local optic flow direction, while slow phase speed is about half of the local speed. Higher directional gains are observed when averaging the entire optical flow projected on the simulation display, whereas the best speed gain is obtained for a 2° optic flow area, centered on the instantaneous gaze location. The present study confirms that the tangent point is a privileged feature in the dynamic visual scene during curve driving, and underlines a contribution of the global optical flow to gaze behavior during active self-motion.     

Cortical blindness and occipital lobe seizures induced by cis-platinum

Three patients developed occipital lobe seizures as a manifestation of diaminodichloro platinum (DDP) toxicity. They were characterized in two patients by cortical blindness, ictal nystagmus and a confusional state. The third patient had visual hallucinations followed by grand mal seizures. All the abnormalities in these patients responded to anticonvulsant therapy.     

Spatial distribution of local flash electroretinogram by multi-input stimulation

A method was developed for recording the distribution of the local flash electroretinogram with multi-input stimulation. With the use of a long flash interval, such as 100 ms, the principle and the method are useful for clinicians who know the method for recording the conventional local flash electroretinogram with single-input stimulation. This method results in a long recording time, yet it presents real local flash electroretinogram waveforms at the output.