Rod monochromatism and blue cone monochromatism: pupillary, accommodative and convergence reactions to darkness.

PURPOSE: To elucidate the mechanism of paradoxical pupillary constriction to darkness (PPCD) and the clinical characteristics facilitating this phenomenon. METHODS: Six rod monochromats, three blue cone monochromats, with three obligate BCM carriers, and ten age matched controls were studied. Pupillary responses, refractions and eye positions were measured with an infrared refractometer, with and without background room lighting while being simultaneously recorded on VHS (infrared) video tape from onset of darkness. RESULTS: Only rod monochromats displayed typical paradoxical pupillary responses. Blue cone monochromats and obligate BCM carriers showed reduced pupillary contraction, compared to controls, but no paradoxical pupillary reaction. Changes neither in accommodation nor convergence were found during paradoxical pupillary constriction to darkness in our rod monochromats. CONCLUSIONS: Paradoxical pupillary constrictions to darkness were seen in rod monochromats but were found not to be age or gender related. This constriction was accompanied neither by accommodation nor convergence changes. No significant differences in pupillary responses to darkness were observed in BCMs nor their carriers, although pupillary dilation to darkness seemed slightly impaired as compared to normals.

Relationships among visual acuity demands, convergence, and nystagmus in patients with manifest/latent nystagmus.

BACKGROUND: We investigated the role convergence plays in nystagmus dampening, in particular, relationships among visual acuity demands, convergence, and nystagmus. Previously we showed that subjects with idiopathic infantile nystagmus exhibit a range of responses to acuity targets, one of which is nystagmus blockage syndrome. We report herein eye movement responses to acuity targets of patients with manifest/latent nystagmus. METHODS: Fourteen patients, 11 with latent or manifest latent nystagmus and 3 with combined manifest latent with infantile nystagmus, were asked to indicate the direction of the gap in Landolt C optotypes while their eye movements were recorded. RESULTS: The tested patients exhibited various responses to acuity demands: (1) dampening of nystagmus with convergence (i.e., nystagmus blockage syndrome) (5/14 patients), (2) changes in vergence without nystagmus dampening (2 patients), (3) decrease of nystagmus without convergence (2 patients), and (4) little change in nystagmus or vergence (5 patients). In nystagmus blockage syndrome the amount of convergence increased with acuity demands in two of five patients and the convergence duration in four of five patients; nystagmus dampening increased with acuity demands in one of five patients and the blockage duration in four of five patients. CONCLUSIONS: Many, but not all, patients with manifest/latent nystagmus, similar to those with infantile nystagmus, used convergence to dampen their nystagmus. The convergence response tended to increase with acuity demands, but the amount of dampening was idiosyncratic and not predictably related to the measured convergence across patients.

Congenital periodic alternating nystagmus. Diagnosis and Management.

PURPOSE: The purpose of the study is to investigate diagnostic criteria and treatment methods for patients with congenital periodic alternating nystagmus (PAN). METHODS: A retrospective analysis was performed of clinical findings and serial eye movement recordings of patients with congenital PAN. Eighteen patients observed from 1983 through 1996 and diagnosed with congenital PAN are included. Five of these have ocular or oculocutaneous albinism. Nine of the 18 patients were treated. Three had Kestenbaum operations before referral to the authors, one was treated with baclofen, and five had large recessions of the four horizontal recti. The studied parameters included visual acuity (VA) and abnormal head posture (AHP); temporal aspects of PAN cycle, nystagmus waveforms, frequency, amplitude, and velocity; as well as mean foveation fraction, a mean percentage of the nystagmus cycle spent at retinal slip velocities less than 10 degrees per second. RESULTS: The authors diagnosed PAN in 9% of patients with congenital nystagmus, although most had not been diagnosed with PAN before referral, despite changing nystagmus. Sixteen patients had AHP, typically shifting. The PAN cycle was of variable duration, often with asymmetric right- and left-beating components. Although horizontal jerk nystagmus with accelerating slow phase was predominant, other waveforms were encountered in the active phase of PAN. In the quiet phase (close to null zone), similar, but less intense, oscillations than those in the active phase were characteristic. Half of the patients showed a combination of waveforms in both phases. Baclofen treatment was unsuccessful. Patients who had Kestenbaum procedures remained with AHP in the original or opposite direction, without change in nystagmus or VA. Large recessions of four horizontal recti proved uncomplicated. This treatment improved, at least for several years, AHP and VA and caused favorable changes in nystagmus parameters in all patients. Mean foveation fractions increased significantly after surgery. CONCLUSIONS: Congenital PAN often is underdiagnosed. Differing waveforms may indicate PAN. Evaluation of nystagmus, especially before surgery, for at least 3 minutes, preferably with eye movement recordings, is necessary to diagnose PAN and perhaps prevent Kestenbaum procedures, which seem inappropriate. Large horizontal recti recessions seem to provide safe and promising treatment.

Costenbader Lecture. Idiopathic infantile nystagmus: diagnosis and treatment.

Current concepts of idiopathic infantile nystagmus are summarized, with special attention to treatment and differential diagnosis of this condition. Advantages of the Anderson procedure over the Kestenbaum procedure are suggested for head turn associated with this condition, and the need for further studies is acknowledged. The importance of the extended slow phase in understanding the waveforms of infantile nystagmus is stressed. Our studies reinforce what I believe to be the natural history of infantile nystagmus, as well as the history of periodic alternating nystagmus. The critical delineation of diagnosing periodic alternating nystagmus is emphasized with respect to the type of operation to avoid overcorrection of head turns in patients with nystagmus. Continued searches for manifest latent nystagmus are important, because that condition is currently the only truly treatable nystagmus. I thank the American Association for Pediatric Ophthalmology and Strabismus for the privilege and honor of presenting the 1997 Costenbader Lecture.

Head and eye movements in children with low vision.

BACKGROUND: Early childhood nystagmus may herald blindness, brain tumors, benign idiopathic motor nystagmus or spasmus nutans. Nystagmus unique to low vision was sought. METHODS: Videotapes and head/ eye movements of 18 congenitally visually impaired subjects were analyzed. RESULTS: Nystagmus of congenitally visually impaired subjects was characterized as small horizontal or vertical movements superimposed on larger oscillations. Small and large nystagmus movements were of pendular or jerk type. Slow-phase jerk nystagmus had increasing, constant and decreasing velocities. Fast-phase nystagmus changed direction periodically. Pendular nystagmus was out of phase and evolved to jerk nystagmus in two subjects. All subjects displayed head nodding, and one stabilized gaze with head movements. CONCLUSION: Eye movement recordings allow characterization and differentiation of subjects with nystagmus and low vision from other nystagmus forms.

Spasmus nutans. A long-term follow-up.

PURPOSE: Nystagmus, head nodding, and anomalous head position are symptoms of spasmus nutans. This disorder appears in early childhood and is thought to be self-limited. However, the visual outcome of patients with spasmus nutans is unclear. The resolution of nystagmus has not been proven with quantitative eye movement recordings. The purpose of this study was to perform long-term follow-up examinations (mean, 5.5 years) of patients with spasmus nutans. METHODS: Ten patients with spasmus nutans were followed up clinically until a mean age of 7 years. Included were quantitative eye and head movement recordings. RESULTS: At their last examination (mean age, 7.1 years), visual acuity in four patients was 20/20 in both eyes, in five patients it was 20/30 or better in at least one eye, and in one patient it was 20/50 in each eye. Three patients had orthotropia with normal stereo acuity. The remaining patients had esotropia, dissociated vertical deviation, amblyopia, or latent nystagmus. All patients had fine, intermittent asymmetric, pendular nystagmus on eye movement recordings. CONCLUSIONS: Good visual acuity can be expected in patients with spasmus nutans; one third have normal stereo acuity. However, subclinical nystagmus persists until at least 5 to 12 years of age.

Visual acuities and scotomas after 3 weeks' levodopa administration in adult amblyopia.

BACKGROUND: Previous studies have shown that both a single dose of levodopa and a 1-week administration of levodopa improve visual functions in adult amblyopic patients. In the present study, we investigated the effect of increased dosage and duration of levodopa on amblyopes' visual functions. METHODS: Visual acuity and visual fields were examined before and after 3 weeks of daily administration of levodopa/carbidopa as well as 1 month and 2 months after completion of drug therapy in a double masked-design. RESULTS: A significant increase in visual acuities and a decrease in fixation point scotomas were found. Changes were of comparable dimension to those found after 1 week of levodopa administration. Improvement of visual functions persisted 2 months after the levodopa/carbidopa administration was completed. CONCLUSION: The present study confirms previous findings of improvement in visual function in amblyopia after levodopa/carbidopa administration. However, increasing the dosage and the duration of levodopa did not enhance the effect in adults.

Quantitative eye and head movement recordings of retinal disease mimicking spasmus nutans.

PURPOSE/METHODS: To investigate whether quantitative head and eye movement recordings can distinguish patients with spasmus nutans from patients with retinal diseases mimicking spasmus nutans. A patient with congenital stationary night blindness was followed up for seven years with electro-oculographic eye movement recordings. RESULTS/CONCLUSIONS: Rhythmic head movements and fine, intermittent, asymmetric, disconjugate, high-frequency, out-of-phase pendular nystagmus were recorded. Eye and head movement recordings of patients with congenital stationary night blindness can mimic spasmus nutans.

Treatment of acquired nystagmus with botulinum neurotoxin A.

OBJECTIVE: Acquired nystagmus may cause oscillopsia and in some cases decreased visual acuity. Such symptoms may be debilitating. We evaluated the efficacy of retrobulbar botulinum neurotoxin A in the visual rehabilitation of patients with acquired symptomatic nystagmus. PATIENTS: Adults with acquired nystagmus from multiple sclerosis or brain-stem hemorrhage were recruited for this treatment study. Eligible patients were unable to perform visual tasks that they had performed prior to the onset of the nystagmus. DESIGN AND INTERVENTION: A prospective study evaluated the results of the retrobulbar injection of 25 to 30 U of botulinum neurotoxin A. Patients underwent testing of visual function, including eye movement recordings before and after initial injections. Patients were followed up for changes in their visual function for at least 6 months following the last injection. RESULTS: Six patients (nine eyes) with acquired nystagmus were treated with a series of 17 injections of retrobulbar botulinum neurotoxin A. Each patient had subjective and objective improvement in distance visual acuity following the injection. A reduction in the amplitude of the nystagmus was seen following each of the injections, but the frequency of the nystagmus was generally unchanged. Visual improvement usually lasted no more than 8 weeks. However, improvement persisted for 6 months after injection in two patients with oculopalatal myoclonus. CONCLUSION: Botulinum neurotoxin A transiently improves the visual function of patients with acquired nystagmus. For patients with oculopalatal myoclonus the improvement seems to last longer, about 6 months in two patients.

Eye and head movements in patients with achromatopsia.

The diagnosis of patients with rod monochromatism (RM) and blue-cone monochromatism (BCM) may be difficult. The relative direction and symmetry of nystagmus of the two eyes, as well as the existence or nature of rhythmic head movements, are not known. We analyzed simultaneous eye and head movement recordings of 16 patients with RM and three patients with BCM. Longitudinal examinations were performed in seven patients. Younger patients had pendular, intermittent or continuous oblique nystagmus with both eyes oscillating in phase or out of phase with equal amplitudes. Older patients had continuous symmetrical oblique jerk nystagmus with decreasing velocities in the slow phase. In two children, we demonstrated evolution from pendular to predominantly jerk nystagmus. Rhythmic head movements were detected in all children. Patients with RM and BCM exhibit a distinct entity of nystagmus and can be differentiated from patients with congenital or latent nystagmus. However, eye and head movements can mimic spasmus nutans.

Dissociated vertical deviation (DVD): The saccadic and slow eye movements.

Dissociated vertical deviation (DVD), a vertical strabismus, is often associated with infantile esotropia, latent nystagmus and excyclo-torsion. DVD usually becomes apparent at about three years of age. The authors wished to determine whether DVD is a manifestation of an abnormal motor vergence system or is part of a visual system disorder. Vertical eye movements of six subjects with DVD, on cover-uncover and alternate cover tests, were studied using the magnetic search eye coil system. Asymmetry between the eyes' saccades were quantified during the DVD upward movement and during a trial of pure vertical saccades. In three subjects the vertical deviation increased to its full amount through a smooth vertical divergence movement, and in the other three patients through a combination of smooth and asymmetrical saccade-like movements. The latencies of the DVD, the peak velocity of the deviation movements, its time constant and the asymmetries in the saccades suggest that DVD represents an abnormal vertical vergence system.

Improvement of visual acuity after surgery for nystagmus.

PURPOSE: The authors compared the preoperative and postoperative binocular visual acuities and eye movement recordings of patients who underwent eye muscle surgery consisting of the Anderson-Kestenbaum procedure or the artificial divergence procedure modeled after Cüppers, or a combination of both procedures, for the treatment of infantile nystagmus with head turn. METHODS: Binocular visual acuities and eye movement recordings by electro-oculography (EOG) were compared preoperatively with those done within 3 weeks postoperatively. Shifting and broadening of the minimal intensity zone and foveation time and changing of the waveform were measured. The treatment of 6 of 18 patients was based on the artificial divergence principle; for 7 patients, treatment was in accordance with the Anderson-Kestenbaum principle; and 5 patients had combined procedures. RESULTS: The improvement in binocular visual acuities was two Snellen lines or more in one of six patients in the artificial divergence group and four of five patients in the combined treatment group. The EOG recordings showed shifting of the minimal intensity zone toward the primary position in all three groups. A broadening of the minimal intensity zone occurred mostly in the artificial divergence and combined groups. Increases in foveation time and changes in waveforms from jerk to jerk with foveation were found in three of six patients in the artificial divergence group and in two of five patients in the combined group. CONCLUSION: With less muscle surgery, the artificial divergence and combined operations gave better vision improvement than the Anderson-Kestenbaum operation.

Visual acuities and scotomas after one week levodopa administration in human amblyopia.

The authors previously showed that a single dose of levodopa improves the contrast sensitivity and decreases the size of fixation point scotomas in amblyopic patients. In the present study, they investigated the effect of levodopa after 1 wk of daily administration using a cross-over, double masked design. The decrease of fixation point scotomas was confirmed with automatic static perimetry. An improvement of visual acuity occurred in 70% of the patients after 1 wk of levodopa administration compared to only 22% in the authors' previous study using one single dose. The improvements in visual acuities and visual fields persisted even after the levodopa administration was completed.

Head nodding is compensatory in spasmus nutans.

BACKGROUND: Spasmus nutans is defined as asymmetric nystagmus with associated head nodding in childhood. It is not clear whether head nodding is a compensatory mechanism to control the nystagmus or an involuntary movement of pathologic origin. METHODS: The authors analyzed the relation between head and eye movements by simultaneous eye and head movement recordings of 35 patients with spasmus nutans. RESULTS: In 21 of these patients, the fine, fast, dissociated nystagmus changed during head nodding to larger and slower symmetric eye movements with both eyes oscillating at the same amplitude in phase and 180 degrees out of phase to the head movements, corresponding to a normal compensatory vestibulo-ocular reflex. CONCLUSION: These findings indicate that head nodding is compensatory in spasmus nutans.

Visual-evoked cortical potentials in dissociated vertical deviation.

It is debatable whether chiasmatic misrouting of temporal optic-nerve fibers (similar to that found in ocular albinism) is also characteristic of dissociated vertical deviation. Pattern appearance, pattern reversal, and diffuse-flash, monocular full-field visual-evoked cortical potentials were recorded from albino and normal human subjects and subjects with dissociated vertical deviation. Pattern appearance was the most reliable stimulus for evaluating lateralization (albino-type misrouting) in adult albino patients, and diffuse-flash stimulation was almost as reliable in children. Pattern reversal was found to be an unreliable indicator. Lateralization was not evident among patients with dissociated vertical deviation, as determined by the three modes of stimulation. Our data supported earlier findings that pattern appearance is the most appropriate technique to detect lateralization. Our findings differed from those of previous reports in demonstrating that reliability of the lateralization phenomenon increases with age up to approximately 15 years. Pattern reversal stimulation was not reliable in patients with horizontal nystagmus.

Skin impedance comparisons of electrodes for electro-oculography.

In an effort to define the most comfortable electrode needing the simplest skin preparation with low and stable skin impedance, we compared the impedance between skin electrodes and Stat-Trace II St-102 EKG electrodes (Niko Med USA, New Brunswick, NJ)--the latter being renamed "dry electrodes" because they are used without electrolyte paste--on 12 normal subjects with two different skin preparations, with and without alcohol. The dry electrodes were found to have lower impedance than the skin electrodes. With each skin preparation the alcohol scored better, 7.2 kOhm vs 16.5 kOhm, respectively, and "no preparation" worse, 13.8 kOhm vs 22.7 kOhm, respectively, (but still acceptable when the dry electrode was used). The dry electrode's impedance was quite stable from the moment of application while the skin electrode's impedance drifted dramatically for 30 minutes. If the dry electrode was halved in area of skin contact, as often is necessary with the nasal electrode in children, the impedance rose proportionally but remained acceptable. We conclude that the new dry electrodes give us improved electro-oculography records and suggest their use, particularly for infants and young children where ease of application and simple skin preparation are particularly important.