Clinical and ocular motor analysis of the infantile nystagmus syndrome in the first 6 months of life.

BACKGROUND/AIMS: The infantile nystagmus syndrome (INS) usually begins in infancy and may or may not be associated with visual sensory system abnormalities. Little is known about its specific waveforms in the first 6 months of life or their relation to the developing visual system. This study identifies the clinical and ocular motility characteristics of the INS and establishes the range of waveforms present in the first 6 months of life. METHODS: 27 infants with involuntary ocular oscillations typical of INS are included in this analysis. They were evaluated both clinically and with motility recordings. Eye movement analysis was performed off line from computer analysis of digitised data. Variables analysed included age, sex, vision, ocular abnormalities, head position, and null zone, neutral zone characteristics, symmetry, conjugacy, waveforms, frequencies, and foveation times. RESULTS: Ages ranged from 3 to 6.5 months (average 4.9 months). 15 patients (56%) had abnormal vision for age, nine (33%) had strabismus, five (19%) had an anomalous head posture, 13 (48%) had oculographic null and neutral positions, nine (33%) had binocular asymmetry, and only two showed consistent dysconjugacy. Average binocular frequency was 3.3 Hz, monocular frequency 6.6 Hz. Average foveation periods were longer and more "jerk" wave forms were observed in those patients with normal vision. CONCLUSIONS: Common clinical characteristics and eye movement waveforms of INS begin in the first few months of infancy and waveform analysis at this time may help with both diagnosis and visual status.

Onset of oscillopsia after visual maturation in patients with congenital nystagmus.

PURPOSE: To describe the clinical and oculographic characteristics of a cohort of five patients with congenital nystagmus (CN) and late-onset oscillopsia caused by a coincidental decline in other visual and/or ocular motor functions. DESIGN: Retrospective, observational, case series. PARTICIPANTS: Five visually mature patients with CN and recent-onset oscillopsia were evaluated clinically and with motility recordings. INTERVENTION: Eye movement analysis was performed off-line by computer analysis of digitized data. Nystagmus was analyzed for null-zone characteristics, waveforms, frequency, amplitudes, and slow-phase drift velocity during foveation. Surgical and medical treatment of associated ocular conditions in four of five patients. MAIN OUTCOME MEASURES: Presence of symptomatic oscillopsia and average time during foveation periods of slow-phase drift velocity less than 10 degrees /second. RESULTS: One of the five patients had associated rod-cone dystrophy, and another had recurrence of childhood head posturing with return of an eccentric null zone. The remaining three patients had decompensated strabismus associated with their oscillopsia. All five patients complained of oscillopsia in primary position that was relieved in the four who received treatment. Treatment included prismatic correction in one patient and surgery in three. Recordings in primary position after treatment showed increased duration during foveation periods of slow-phase drift velocity less than 10 degrees /second and an overall decreased intensity (amplitude/frequency) of the nystagmus. CONCLUSIONS: Symptomatic oscillopsia in patients with CN is unusual. This visually disturbing symptom can be precipitated by new or changing associated visual sensory conditions (e.g., decompensating strabismus, retinal degeneration). If the associated conditions can be treated, then accompanying oscillopsia may be relieved.

Computerized method of visual acuity testing: adaptation of the amblyopia treatment study visual acuity testing protocol.

PURPOSE: To report a computerized method for determining visual acuity in children using the Amblyopia Treatment Study visual acuity testing protocol. METHODS: A computerized visual acuity tester was developed that uses a programmed handheld device that uses the Palm operating system (Palm, Inc, Santa Clara, California). The handheld device communicates with a personal computer running a Linux operating system and 17-inch monitor. At a test distance of 3 m, single letters can be displayed from 20/800 to 20/12. A C program on the handheld device runs the Amblyopia Treatment Study visual acuity testing protocol. Using this method, visual acuity was tested in both the right and left eyes, and then the testing was repeated in 156 children age 3 to 7 years at four clinical sites. RESULTS: Test-retest reliability was high (r =.92 and 0.95 for and right and left eyes, respectively), with 88% of right eye retests and 94% of left eye retests within 0.1 logarithm of minimal angle of resolution (logMAR) units of the initial test. The 95% confidence interval for an acuity score was calculated to be the score +/- 0.13 logMAR units. For a change between two acuity scores, the 95% confidence interval was the difference +/- 0.19 logMAR units. CONCLUSIONS: We have developed a computerized method for measurement of visual acuity. Automation of the Amblyopia Treatment Study visual acuity testing protocol is an effective method of testing visual acuity in children 3 to 7 years of age.

Clinical and oculographic response to Dexedrine in a patient with rod-cone dystrophy, exotropia, and congenital aperiodic alternating nystagmus.

PURPOSE: We report a child with retinal dystrophy and congenital (a)periodic alternating nystagmus (APAN) who responded immediately with improved visual function and electrooculographic parameters after taking the psychopharmacologic stimulant Dexedrine Spansule (Glaxo-Smith Kline, NC, USA) as part of treatment for his Attention Deficit Disorder. DESIGN: Interventional case report. METHODS: General ophthalmic, ocular motor and sensorimotor examinations and ocular motility recordings were performed before and after administration of the drug Dexedrine Spansule. RESULTS: The patient's binocular visual acuity improved only at 1.5 after medicine hours from 20/63 to 20/50, his exotropic deviation decreased from 25 to 10 prism diopters, his stereopsis increased from none to 800 sec/arc and ocular motility recordings showed increased foveation periods and more and lengthened APAN transition/null zones. CONCLUSION: For unexplained reasons the stimulant Dexedrine "paradoxically" improved the nystagmus, binocular function and visual acuity in this patient with retinal dystrophy and congenital nystagmus. This observation may be the basis for investigation of a new pharmacological treatment approach to patients with congenital nystagmus or strabismus.

Marked variability amongst pediatric ophthalmologists in designating the diagnostic gaze position angles in ocular motility evaluations.

BACKGROUND: Management of strabismus relies on accurate evaluation of binocular alignment in standard gaze positions. In 1962, Stuart & Burian noted that, without adopting a standard routine, "measurements of various patients could not be compared, and there will be considerable difference in measurement from one examination to another and by different examiners" (1). Diagnostic position gaze angles are not routinely measured. Is this important? SUBJECTS AND METHODS: Subjects were 82 volunteer experts recruited from attendees at the 1998 American Association for Pediatric Ophthalmology and Strabismus (AAPOS) scientific meeting. One author served as examinee for all testing. The actual head posture was measured for the expert designated primary position, right and left gazes, head tilts and up- and downgazes using the CROM device. The examinee fixated at a six meter distance accommodative target. Examiners were asked to mimic their office routine. Eighty-two subjects ranging from 29 to 69 years of age, consisting of 24 females and 58 males were recruited. Sixty-nine were pediatric ophthalmologists, 7 orthoptists, 4 international members and 2 members in training. Eight subjects also underwent re-testing. Years in practice averaged 11.5. RESULTS: Range of head posture measurements: For "Horizontal Gaze": 10 to 50 degrees; For "Vertical Gaze": 4 to 58 degrees; For "Head Tilts": 20 to 50 degrees. There was no substantial difference between initial and repeat measurements. CONCLUSION: There is a surprisingly high degree of variability amongst expert observers in defining standard gaze positions. These results may explain some of the inconsistent outcomes noted in the strabismus literature. The implication for transferring data from publication to practice and in designing multicentered protocols is concerning. Without defining and maintaining a standard for binocular alignment measurements, comparison between studies and examiners is not possible.

The amblyopia treatment study visual acuity testing protocol.

OBJECTIVE: To evaluate the reliability of a new visual acuity testing protocol for children using isolated surrounded HOTV optotypes. METHODS: After initial pilot testing and modification, the protocol was evaluated using the Baylor-Video Acuity Tester (BVAT) to present isolated surrounded HOTV optotypes. At 6 sites, the protocol was evaluated for testability in 178 children aged 2 to 7 years and for reliability in a subset of 88 children. Twenty-eight percent of the 178 children were classified as having amblyopia. RESULTS: Using the modified protocol, testability ranged from 24% in 2-year-olds to 96% in 5- to 7-year-olds. Test-retest reliability was high (r = 0.82), with 93% of retest scores within 0.1 logMAR unit of the initial test score. The 95% confidence interval for an acuity score was calculated to be the score +/-0.125 logMAR unit. For a change between 2 acuity scores, the 95% confidence interval was the difference +/-0.18 logMAR unit. CONCLUSIONS: The visual acuity protocol had a high level of testability in 3- to 7-year-olds and excellent test-retest reliability. The protocol has been incorporated into the multicenter Amblyopia Treatment Study and has wide potential application for standardizing visual acuity testing in children.

Examination and refractive management of patients with nystagmus.

Patients with nystagmus present unique challenges to the ophthalmologist. These patients can be difficult to examine and refract. Treatment options to improve vision or reduce disturbing visual symptoms are limited, which is disappointing to the patient and frustrating to the clinician. This paper will provide the clinician with one method of clinically organizing nystagmus, describe the patients who may benefit from optical treatments, and discuss the methodology used in their implementation. Techniques that will be discussed include patient examination and objective and subjective refraction. Optical treatments discussed include spectacles, prisms, contact lenses, and retinal image stabilization.

Ocular motor signs in an infant with carbohydrate-deficient glycoprotein syndrome type Ia.

PURPOSE: To document the evolution of ocular motor abnormalities in an infant with carbohydrate-deficient glycoprotein syndrome. METHODS: Case report. An infant with carbohydrate-deficient glycoprotein syndrome type 1a underwent magnetic resonance imaging and infrared eye movement recording. RESULTS: A 10-month-old male with carbohydrate-deficient glycoprotein syndrome type Ia had rapid horizontal oscillations of the eyes when startled or awakened from sleep. Clinical examination confirmed this finding and disclosed congenital ocular motor apraxia with a reduced vestibulo-ocular reflex. Infrared eye movement recording showed ocular flutter and square wave jerks superimposed on a horizontal pendular nystagmus. Magnetic resonance imaging showed diffuse cerebellar hypoplasia. CONCLUSION: Carbohydrate-deficient glycoprotein syndrome type Ia can be associated with multiple cerebellar eye signs including ocular flutter, square-wave jerks, and congenital ocular motor apraxia.

Oculographic and clinical characterization of thirty-seven children with anomalous head postures, nystagmus, and strabismus: the basis of a clinical algorithm.

BACKGROUND AND PURPOSE: We studied children with nystagmus who also had anomalous head postures and strabismus to determine the etiology of the conditions and present a diagnostic clinical algorithm. METHODS: The patients for this study were among the 560 patients evaluated in the ocular motor neurophysiology laboratory between the years 1991 and 1997. Clinical characteristics, infrared oculography data, and medical and surgical treatments were entered into a database for analysis. Oculography was performed on all patients according to a standard protocol, and data were stored and analyzed off-line. Etiology of anomalous head posture was determined with both clinical and oculography information. RESULTS: Thirty-seven children are the subjects of this report. The etiology of anomalous head posture was a "gaze null" due to congenital nystagmus in 23 (62%) patients, an "adduction null" due to manifest latent nystagmus in 12 (32%) patients, spasmus nutans in 1 (3%) patient, and strabismus in 1 (3%) patient. The patients' ages ranged from 9 months to 12 years and averaged 4.4 years. Sixty-nine percent were male patients. Nineteen (63%) of 30 patients had abnormal recognition (linear optotype) acuity in at least 1 eye on monocular cover; the recognition remained abnormal in 5 (17%) of 30 patients under binocular conditions. Thirty percent of patients had amblyopia, 16% had some structural disease of the eyes, 22% had some systemic syndrome or abnormality, 57% had a significant refractive error, and 27% had some ability to fuse. CONCLUSIONS: The major etiology for anomalous head posture in these patients was to adopt a gaze null due to congenital nystagmus (62% of patients) regardless of the direction of their anomalous head posture or type of strabismus. Moving the fixing eye as the first step for the anomalous head posture, combined with moving the nonfixing eye for the resulting strabismus may help treat these patients.

A new surgery for congenital nystagmus: effects of tenotomy on an achiasmatic canine and the role of extraocular proprioception.

PURPOSE: Human eye-movement recordings have documented that surgical treatment of congenital nystagmus (CN) also produces a broadening of the null zone and changes in foveation that allow increased acuity. We used the achiasmatic Belgian sheepdog, a spontaneously occurring animal model of human CN and see-saw nystagmus (SSN), to test the hypothesis that changes induced by surgical interruption of the extraocular muscle afference without a change in muscle-length tension could damp both oscillations. METHODS: An achiasmatic dog with CN and SSN underwent videotaping and infrared oculography in a sling apparatus and head restraints before and after all extraocular muscles (stage 1: 4 horizontal rectus muscles and stage 2 [4 months later]: 4 vertical rectus muscles and 4 oblique muscles) were surgically tenotomized and immediately reattached at their original insertions. RESULTS: The dog had immediate and persistent visible, behavioral, and oculographic changes after each stage of this new procedure. These included damped CN and SSN, increased ability to maintain fixation, and increased periods of maintaining the target image on the area centralis over a broad range of gaze angles. CONCLUSIONS: Severing and reattaching the tendons of the extraocular muscles affect some as-yet-unknown combination of central nervous system processes producing the above results. This new procedure may prove effective in patients with CN with either no null, a null at primary position, or a time-varying null (due to asymmetric, (a)periodic, alternating nystagmus). We infer from our results in an achiasmatic dog that tenotomy is the probable cause of the damping documented in human CN after Anderson-Kestenbaum procedures and should also damp CN and SSN in achiasma in humans. It may also prove useful in acquired nystagmus to reduce oscillopsia. The success of tenotomy in damping nystagmus in this animal suggests that the proprioceptive feedback loop has a more important role in ocular-motor control than has been appreciated. Finally, we propose a modified bimedial recession procedure, on the basis of the damping effects of tenotomy.

Retinal hemorrhages caused by accidental household trauma.

Traumatic retinal hemorrhages in young children are considered pathognomonic of child abuse. We identified 3 children with unilateral retinal hemorrhages caused by accidental household trauma. The hemorrhages were ipsilateral to intracranial hemorrhage and isolated to the posterior retinal pole.

Clinical and ocular motor analysis of congenital nystagmus in infancy.

PURPOSE: The purpose of this study was to identify the clinical and ocular motility characteristics of congenital nystagmus and to establish the range of waveforms present in infancy. BACKGROUND: The clinical condition of congenital nystagmus usually begins in infancy and may or may not be associated with visual sensory system abnormalities. Little is known about its specific waveforms in infancy or their relationship to the developing visual system. METHODS: Forty-three infants with involuntary ocular oscillations typical of congenital nystagmus were included in this analysis. They were evaluated both clinically and with motility recordings. Eye movement analysis was performed off line from both chart recordings and computer analysis of digitized data. Variables analyzed included age, sex, vision, ocular abnormalities, head position, null-zone or neutral-zone characteristics, symmetry, conjugacy, waveforms, frequencies, foveation times, and responses to convergence and to monocular cover. RESULTS: Patient ages ranged from 3 to 18 months (average, 9.2 months). Seventeen patients (40%) had abnormal vision, 3 had a positive family history of nystagmus, 11 had strabismus, 16 (37%) had a head posture, 26 (60%) had null and neutral positions, 14 (33%) had binocular asymmetry, and all were horizontally conjugate. Average binocular frequency was 2.8 Hz, and average monocular frequency was 4.6 Hz. The waveforms were both jerk and pendular; average foveation periods in patients with normal vision were more than twice as long as those in patients with abnormal vision. CONCLUSIONS: Common clinical characteristics and eye-movement waveforms of congenital nystagmus begin in infancy, and waveform analysis at this time helps with both diagnosis and visual status.

Correlation of postoperative extraocular muscle suture adjustment with its immediate effect on the strabismic deviation.

PURPOSE: To determine if any relationship exists between the amount of adjustment using this surgical technique and resulting changes in the strabismic deviation. METHODS: A prospective database obtained between the years 1991 and 1996 was used to obtain retrospective clinical information and data for this study. We found in the database 172 postoperatively adjusted muscles in 159 patients who could be included in this study. All patients had their muscles adjusted postoperatively within the first 24 hours after surgery. Information retrieved specific to this study included the post-surgical, pre-adjustment strabismic deviation, the amount and direction of the adjustment and the resulting deviation immediately after this postoperative adjustment. Statistical analysis was performed on the total and individual muscles, as well as the direction of adjustment, comparing pre- to post-adjustment binocular deviations. RESULTS: There was a significant overall relationship between the millimeters of postoperative adjustment and the amount of change in the binocular deviation (p<.0001). This relationship was more linear under 3.0 mm of postoperative adjustment. The effect of the amount of postop' adjustment when advancing the muscle was significantly greater than when recessing the muscle (p<.0001). There was more effect per mm of postop' adjustment of horizontal muscles than vertical muscles (p=.004). CONCLUSIONS: There is a linear correlation of postoperative extraocular muscle adjustment when advancing an adjustable muscle but this correlation is more variable for adjustments over 3.0 mm. The effect of adjustment per mm is greater when adjusting horizontal than vertical muscles. There is a poor correlation for further recession. Prediction Equations are provided to enhance clinical results of this technique.