Acquired pendular nystagmus

A case of acquired pendular nystagmus is reported in a patient with multiple sclerosis. The nystagmus is vertical and monocular. The nystagmus is binocular after eye closure and is present only in primary position. During exacerbation of multiple sclerosis the pendular nystagmus disappears while bilateral internuclear ophthalmoplegia and rebound nystagmus are observed. On disappearance of internuclear ophthalmoplegia and rebound nystagmus, the pendular nystagmus reappeared.     

Cabergoline in prolactinomas

Cabergoline is a potent, D2-selective new dopamine agonist with a half-life of 65 hours. We report two cases and review the literature on cabergoline in prolactinomas. Cabergoline appears to be more effective and better tolerated than bromocriptine, compliance may be improved, and costs are comparable. In cases of bromocriptine failure, unusually high starting doses of cabergoline may be necessary. Cabergoline may eventually replace bromocriptine as the drug of choice in prolactinomas.     

Time-varying, slow-phase component interaction in congenital nystagmus

We investigated the nystagmus of a 12-year-old boy with suspected X-linked congenital nystagmus (CN) and exophoria to determine the underlying mechanisms and component signals in the 'dual-velocity' and other slow phases of his Asymmetric (a)Periodic Alternating Nystagmus (APAN). Fast Fourier transforms (FFT) were performed on the waveforms and residual data after subtracting a sawtooth waveform whose amplitude and frequency matched those of the jerk nystagmus. The FFT analyses identified two frequency components (jerk--4 Hz and pendular--4 and 8 Hz, variable) that varied differently in intensity and frequency/phase over the time-course of the APAN. We synthesized each of the patient's slow phases using summation of sawtooth and sinusoidal waveforms. The resulting waveforms included jerk (with different slow-phase appearances), dual jerk, and pendular. We demonstrated that the pendular nystagmus seen during the neutral phase of APAN and the appearance of either decelerating (mimicking latent nystagmus), dual-velocity, or dual-jerk slow phases can be explained and produced by the summation of linear and pendular components of variable amplitudes and frequencies/phases. Thus, one mechanism may be responsible for all the variation seen in this patient's slow phases, rather than the less parsimonious hypothesis of a switched-tonic-imbalance mechanism that we had originally suggested to simulate the dual-velocity waveform.     

眼球震颤的诊断与治疗研究进展

眼球震颤是常见的眼球运动障碍疾病,临床诊治困难。随着近年眼球运动记录方法的进步和药物、手术及基因治疗的研究进展,为临床该病的诊断和治疗提供了更多的选择,也为眼球震颤患者带来新的希望。本文就该病诊断与治疗的最新研究进展进行了综述。     

眼球震颤诊治进展

眼球震颤是指双眼有节律的、不自主的,常呈对称共轭性的异常摆动,可根据发病年龄分为先天性眼球震颤和后天获得性眼球震颤。由于目前有限的诊治手段使得眼球震颤成为较为复杂的眼科疑难疾病之一。近年来,国际和国内对该类疾病的检测和诊疗水平在不断进步。本文将对眼球震颤的分类及特点,检查记录方法以及治疗的新进展进行综述。     

A case of monocular nystagmus blockage syndrome and manifest-latent nystagmus

A 24-year-old man, left eye enucleated at the age of ten months, had jerk-right nystagmus with increasing amplitude in abduction and null position in near-extreme adduction. Under occlusion or in darkness, the nystagmus changed to jerk-left, the amplitude increased in adduction and null position was in abduction; as if his left eye had nystagmus blockage syndrome and he was seeing with this absent left eye! The difference between nystagmus blockage syndrome and latent nystagmus is discussed: nystagmus blockage syndrome is manifested by ‘motor’ maneuver of adduction and abduction, whereas latent nystagmus is induced with ‘sensory’ maneuver of occlusion. It suggests that nystagmus blockage syndrome and latent nystagmus may arise from different mechanisms despite their frequent concurrence.     

The sub-clinical see-saw nystagmus embedded in infantile nystagmus

A transient, decompensated vertical phoria in an individual with infantile nystagmus syndrome (INS) resulted in two images that oscillated vertically-a diplopic oscillopsia. Ocular motor studies during the vertical oscillopsia recreated by vertical prisms, led to the identification of a sub-clinical see-saw nystagmus (SSN), present under the prism-induced diplopic condition. Retrospective analysis of ocular motor recordings made prior to the above episode of vertical diplopia revealed the presence of that same sub-clinical SSN. The SSN had not been detected previously despite extensive observations and recordings of this subject's pendular IN over a period of forty years. Three- dimensional search-coil data from fourteen additional INS subjects (with pendular and jerk waveforms) confirmed the existence of sub-clinical SSN embedded within the clinically detectable horizontal-torsional IN in seven of the fifteen and a sub-clinical, conjugate, vertical component in the remaining eight. Unlike the clinically visible SSN found in achiasma, the cause of this sub-clinical SSN is hypothesized to be due to a failure of the forces of the oblique muscles (responsible for the torsional component of the IN) to balance out the associated forces of the vertical recti; the net result is a small, sub-clinical SSN. Thus, so-called "horizontal" IN is actually a horizontal-torsional oscillation with a secondary, sub-clinical SSN or conjugate vertical component. The suppression of oscillopsia by efference copy in INS appears to be accomplished for each eye individually, even in a binocular individual. However, failure to fuse the two images results in oscillopsia of one of them.     

Adamantiades-Behcet disease: diagnosis and current concepts in management of ocular manifestations

Adamantiades-Behcet disease is a relapsing systemic vasculitis that may involve the eyes, skin, and almost all other organ systems. The comprehensive ophthalmologist plays a key role by not only making the diagnosis but also by monitoring inflammatory status to guide systemic therapy. If left untreated, the disease has a high likelihood of causing blindness and death. Adamantiades-Behcet disease with retinal involvement is now considered an absolute indication for systemic immunomodulatory therapy. The diagnostic signs, potential complications, and treatment modalities currently available for ocular Adamantiades-Behcet disease are reviewed.     

Foveation dynamics in congenital nystagmus II: Smooth pursuit

It has been shown that, during 5 seconds of fixation, an individual with congenital nystagmus (CN) can repeatedly (beat-to-beat) foveate (SD = 12.87 minarc) and maintain low retinal slip velocities (SD = 118.36 minarc/sec). Smooth pursuit data from several CN subjects showed that eye velocities during these foveation intervals approximated target velocity. Despite some claims that CN is caused by absent or reversed smooth pursuit, those with CN hardly ever experience oscillopsia or exhibit any accompanying symptoms of such deficits in pursuit; they are able to master sports requiring tracking of rapidly moving small objects (e.g. racquetball or handball). We developed and describe several new methods to accurately assess the function of smooth pursuit in an individual with typical idiopathic CN. We investigated the dynamics of CN foveation periods during smooth pursuit to test the hypothesis that eye velocities would match target velocities during these periods. Unity or near-unity instantaneous (beat-to-beat) pursuit gains of both experimenter-moved and subject-moved targets at peak velocities ranging from only a few deg/sec up to 210°/sec were measured. The dynamic neutral zone was found to shift oppositely to target direction by amounts proportional to the increase in target speed. Our methods proved that eye velocity is made to match target velocity during the foveation intervals and support the conclusion that smooth pursuit in individuals with CN is functioning normally in the presence of the CN oscillation. In addition, we hypothesize that the same fixation mechanism that prevents oscillopsia during fixation of stationary targets, also does so during pursuit.General Terms CN Congenital nystagmus - CS Catch-up saccade - DNZ Dynamic neutral zone - SNZ Static neutral zone - SD Standard deviation CN Waveforms Jef Jerk with extended foveation - JR(L) Jerk right (left) - JR(L)ef Jerk right (left) with extended foveation - Pfs Pendular with foveating saccades - Pfl(r)s Pendular with left (right) foveating saccades - PPrfs Pseudopendular with right foveating saccades - R(L)PC Right (left) pseudocycloid Calculated (Statistical) Terms Gav Average gain - Gfp Gain calculated during the foveation period - RERfp Mean retinal error position during foveation period     

Foveation dynamics in congenital nystagmus I: Fixation

Congenital nystagmus (CN) has been described as a fixation nystagmus implying an inability to fixate a target. However, each cycle of CN contains a target-foveation period during which the eye velocity is at, or near, zero. Prolongation of foveation time, reduction of retinal image velocity and cycle-to-cycle foveation repeatability all contribute to increased visual acuity. We developed several methods to accurately measure the dynamics of foveation in CN; their use is illustrated on an individual with typical idiopathic CN and no afferent defects. During eight 5-second intervals of fixation on a stationary target, the horizontal standard deviation (SD) of the mean foveation position (FPOS) was 12.82 minarc and the SD of foveation velocity was 118.36 minarc/sec. The SD of the means of total eye position and of the non-foveating peak of the CN were 43.17 and 25.32 minarc respectively. The mean foveation-time interval (eye velocity 4°/sec) was 57.27 msec. The SD FPOS for the best 1-second interval (4 successive CN cycles), in a typical 5-second record, was 0.71 minarc. Histograms revealed peaks of eye position at 0 ± 10 minarc and of eye velocity at 0 ± 240 minarc/sec. The small vertical component of the CN (16 minarc peak-to-peak) had a SD of 6.56 minarc. A nystagmus foveation function related to visual acuity was derived that was more sensitive than CN intensity. The increased visual acuity resulting from the use of convergence or base-out prisms was due to increased foveation time. Although it might appear that CN is a defect of fixation, this individual with CN had strong fixation reflexes in the sense that he was able to accurately (within 1 minarc) achieve (interbeat) and maintain (intrabeat) target foveation for appreciable periods of time. Our data support the hypothesis that individuals with idiopathic CN do not have a primary disturbance of fixation.General Terms AVG DIST Average values during distance fixation - CN Congenital nystagmus - DIST + PRS Fixation at distance with prisms - GANGLE Gaze angle - NFF Nystagmus foveation function - SD Standard deviation (STD) CN Waveforms Jef Jerk with extended foveation - LPC Left pseudocycloid - Pfs Pendular with foveating saccades - PPfs Pseudopendular with foveating saccades Calculated (Statistical) Terms EPOS Mean eye position - FPOS Mean foveation period position - freq Mean frequency of CN - FVEL Mean foveation period velocity - I CN intensity (PPA^*freq) - NFP Mean non-foveating peak position - PPA Mean peak-to-peak amplitude - PSVEL Mean post-saccadic velocity - REPF Mean range of eye position during foveation period - TFOV Mean time (duration) of foveation period - %F/E The SD of FPOS as a percentage of EPOS - %N/E The SD of NFP as a percentage of EPOS - %REP/PPA REP as a percentage of PPA - %TFOV TFOV as a percentage of the CN period (1/freq) - Tf/SDFPV The NFF = (TFOV)(freq)/[(SD FPOS)(SD FVEL)] - kTf/SDFP Approximation to the NFF = k(TFOV)(freq)/(SD FPOS)     

Long-term results of four horizontal rectus muscle recession in nystagmus treatment

Purpose: To report the long-term results of four horizontal rectus muscle recessions that were performed for infantile nystagmus syndrome treatment.

Methods: In this case series, patients with infantile nystagmus syndrome who had four horizontal muscle recessions previously were recruited and ophthalmological examination and electronystagmography recordings were performed. Objectively, amplitude and frequency of nystagmus were measured from the recordings and the intensity was calculated. Visual acuity, stereopsis, and alignment were evaluated and compared with the preoperative and postoperative values.

Results: The records of the 12 patients who had four horizontal rectus muscle recession surgery were evaluated and six patients (5 male, 1 female) who had regular follow-ups were included in this study. Mean follow-up was 14.17?±?0.41 years (minimum 14 years, maximum 15 years) and mean age of patients at the last visit was 22 years (20-28 years). On subjective evaluation, two-thirds (4/6) of the patients were satisfied with the surgical results and had the impression that after surgery, nystagmus decreased in intensity and head posture improved. On objective evaluation, visual acuity was found to be the same, however, stereopsis improved (preoperatively and postoperatively median stereopsis was 600?sec arc vs 200?sec arc final). The decrease in nystagmus amplitude and frequency was still maintained.

Conclusions: Nystagmus surgery on four horizontal rectus muscles has positive effects on binocular function and nystagmus parameters in the long-term follow-up. As we could not treat the primary pathology, the visual acuity was about the same but the decrease in nystagmus amplitude and frequency was still maintained with better stereopsis, and patient satisfaction.     

Foveation dynamics in congenital nystagmus III: Vestibulo-ocular reflex

It has been shown that, during fixation of a stationary target with a fixed head, an individual with congenital nystagmus (CN) can repeatedly (beat-to-beat) foveate (within 13 minarc) and maintain low retinal slip velocities (less than 4°/sec). With the head in motion, vestibuloocular reflex (VOR) data showed eye velocities during these foveation periods that approximation head veloicty. Despite some claims that the VOR of CN subjects was deficient or absent, individuals with CN hardly ever complain of oscillopsia or exhibit any of the symptoms that would accompany such deficits in the VOR, whether during simple walking and running or while skiing down a mogul field. We developed and describe several different and unrelated methods to accurately assess the function of the VOR in an individual with typical idiopathic CN. We investigated the dynamics of CN foveation periods during head rotation to test the hypothesis that eye velocities would match head velocities during these periods. At about 1 Hz, horizontal VOR instantaneous (beat-to-beat) gains were 0.96 in the light and 0.94 in the dark while imagining a stationary target. Vertical VOR gains were 1.00 and 0.99 for these two conditions at the same frequency; the CN was horizontal. Also, during the VOR there is a CN neutral-zone shift comparable to that found during smooth pursuit. Our methods demonstrated that gaze velocity was held constant during foveation periods and we conclude that the VOR in this subject is functioning normally in the presence of the CN oscillation. Based on our findings in this and previous studies, we hypothesize that CN may be due to a peripheral instability.General Terms BS Braking saccade - CN Congenital nystagmus - CS Catch-up saccade - DNZ Dynamic neutral zone - FS Foveating saccade - NFP Non-foveating peak - SNZ Static neutral zone - SD Standard deviation - VOR Vestibulo-ocular reflex CN Waveforms JLef Jerk left with extended foveation - Pfr(l)s Pendular with right (left) foveating saccades - PPr(l)fs Pseudopendular with right (left) foveating saccades - R(L)PC Right (left) pseudocycloid Calculated (Statistical) Terms Gav Average gain - Gfp Gain calculated during the foveation period - RERfp Mean retinal error position during foveation period     

Acute inflammatory demyelinating optic neuritis: current concepts in diagnosis and management.

BACKGROUND: Optic neuritis (ON), defined as an inflammatory demyelinating optic neuropathy, is a frequent cause of visual loss owing to optic nerve dysfunction in young or middle-aged patients. ON can be seen in isolation or in association with multiple sclerosis (MS). Highlighting the importance of this association is the fact that approximately 20% of patients with MS will present with ON. METHODS: Review was conducted of the literature and pertinent clinical trials. CONCLUSION: Although the vision prognosis of patients with ON is excellent, with or without the use of corticosteroids, a minority of patients will suffer from significantly poor vision. ON may be the heralding manifestation of MS; the risk stratification for the future development of MS in patients presenting with ON can be determined by the number of white matter lesions on the baseline cerebral magnetic resonance imaging study. To date, 2 randomized, placebo-controlled studies have found that patients with a clinically isolated demyelinating syndrome, such as ON, at risk for MS, may benefit from the early institution of a disease-modifying drug.     

Postnatal development of optokinetic after nystagmus in human infants

During the first few months of life after birth human infants when tested monocularly move their unoccluded eye nasalward in darkness after viewing a large textured visual field moving either nasalward or temporalward. The eye movements in darkness are optokinetic after nystagmus (OKAN) which is an aftereffect of a reflex horizontal following eye movement, optokinetic nystagmus (OKN). Not until 4-5 months of age did temporalward field motion evoke OKAN with temporalward slow phase. The nasalward slow phase of OKAN that responded earlier to temporalward field motion appears to underlie the delayed development of reflex following eye movements in the temporalward direction.     

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.     

Downbeat nystagmus in an infant: Spontaneous resolution during infancy

Downbeat nystagmus (DBN) has been associated with pathologic as well as idiopathic conditions. DBN may occur during infancy or childhood or may be congenital. In all reported cases, the DBN persisted. The authors report an infant with DBN that resolved within the first year of life.

The patient's DBN was observed by six weeks of age. The patient preferred to keep her head in a chin-down position. Her physical and neurologic examination was otherwise normal. Family history contained no nystagmus. The DBN was documented by both vertical DC electro-oculography and infrared oculography. The DBN slow phases were predominantly of constant velocity. Subsquent magnetic resonance imaging studies and metabolic investigations were negative. The DBN was clinically undetectable at nine months of age. A repeat oculographic study at one year of age confirmed the resolution of DBN.

It is suggested that, in this case, DBN was caused by an immaturity of central connections associated with the vertical canal pathways and its resolution paralleled their later maturation.     

Topical lambda-cyhalothrin in reducing eye oscillations in a canine model of infantile nystagmus syndrome

Purpose:To determine the ocular and systemic safety of using topical Lambda-Cyhalothrin (LCL) in a canine model of infantile nystagmus syndrome (INS). The rationale for this proposal is based on a case study of a patient whose INS improved after inadvertent ocular exposure to a pyrethroid pesticide containing LCL.Methods:After in-vitro safety testing and IUCAC approval, we studied increasing concentrations of topical LCL drops (0.002% to 0.07%) in canines with a purposely bred defect in the RPE65 gene resulting in both retinal degeneration and INS. We collected data on ocular and systemic effects and performed eye-movement recordings (EMR).Results:At the 0.07% concentration dose of LCL, there was minimal, reversible, conjunctival hyperemia. There was no other ocular or systemic toxicity. At the 0.06% dose, there was a visible decrease in the INS and EMR showed a 153%–240% increase in the nystagmus acuity function and a 30%–70% decrease in amplitude across gaze. There was also a 40%–60% decrease in intraocular pressure while on the drop in both eyes.Conclusion:This animal study suggests this new pharmacological agent has potential for topical treatment of both INS and diseases with raised intraocular pressure. Further, this new treatment approach confirms the importance of extraocular muscle proprioception in ocular motor diseases and their treatment.     

Soft Contact Lenses to Optimize Vision in Adults with Idiopathic Infantile Nystagmus: A Pilot Parallel Randomized Controlled Trial

Purpose: The optimal management of infantile nystagmus syndrome (INS) is still unclear. Contact lenses (CL) may be superior to glasses in improving visual function in INS but it is not known whether their beneficial effects are due to optical correction alone, or to an additional proprioceptive effect, and whether soft CLs would be as effective as rigid CLs. There is little data on feasibility and and the present study aimed to provide this information.

Methods: We completed a pilot Randomized Control Trial (RCT) at a single tertiary referral centre in London, UK. We enrolled 38 adults with idiopathic INS and randomised them to either plano CL (with corrective spectacles if required) or to corrective CL. CL wear was required for a minimum of 2 weeks. Primary outcome measures were feasibility and safety of CL wear in INS; secondary outcome measures were visual acuity and nystagmus waveform parameters.

Results: 27 completed the study (27/38,71%). 4 partcipants withdrew due to difficulty with CL insertion/removal and 7 were lost to follow up. CL tolerability was high (24/27,89%) - 2 found the CLs irritant, and 1 had an exacerbation of allergic eye disease. At two weeks, mean improvement in binocular visual acuity from baseline with plano CLs was 0.07 logMAR (95% confidence interval (CI: 0.03-0.11) and 0.06 logMAR with fully corrective CLs (95% CI:0.02-0.1). Mean improvement in the eXpanded Nystagmus Acuity Function (NAFX, a nystagmus acuity function based on eye movement recording) with plano CLs was -0.04(95% CI: -0.08-0.005) and -0.05 with fully corrective CLs(95% CI: -0.09–0.003).

Conclusions: CLs are well tolerated, with a low risk profile. Whilst our study was not powered to detect significant changes in BCVA and waveform parameters between treatment arms, we observed a trend towards an improvement in visual function at two weeks from baseline with CLs.