Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The role of ultrasound biomicroscopy in surgical planning for limbal dermoids

PURPOSE

Limbal dermoids usually involve corneal stroma and more rarely might extend into the anterior chamber. Depending on the size and amount of penetration of the lesion, different therapeutic approaches are indicated. Depth information is difficult to obtain by slit-lamp examination because the structure is opaque. We investigated the use of ultrasound biomicroscopic (UBM) examination for surgical planning in limbal dermoids.

METHODS

The UBM (Zeiss Humphrey) with its 50-MHz probe was used for preoperative evaluation of the depth of penetration in two cases of infantile limbal dermoid. Histology specimens of the lesion corresponding to the UBM images were obtained.

RESULTS

UBM was able to distinguish normal cornea from the more sonolucent lesion. Presence or absence of Descemet's membrane could be identified. Depth of involvement of limbal dermoids could be assessed.

CONCLUSION

UBM is able to assess depth involvement of opaque corneal lesions such as limbal dermoids. Because planning of the surgical approach in these cases is facilitated by preoperative knowledge about the depth of penetration of these opaque lesions, UBM can be regarded as a helpful tool in the clinical management.

Clinical characteristics of surgically treated adult strabismus

BACKGROUND

Strabismus is present in approximately 4% of the population with most forms becoming clinically evident in infancy and childhood. Adult strabismus, including that resulting from recurrent childhood deviations, varies in etiology, presentation, symptomatology, and response to treatment. This report is intended to prospectively characterize adults who required surgical correction of their strabismic deviation.

METHODS

Beginning in 1991, a prospective computerized database was collected that contained all clinical, laboratory, and surgical information on the adult ocular motility service at the Scheie Eye Institute and The Children's Hospital of Philadelphia (Philadelphia, Pa). Analysis of those patients who underwent surgical correction of their strabismus is included in this report. Demography, clinical characteristics, and surgical procedures including results were analyzed separately in adults with their strabismus beginning before visual maturation (BVM) (9 years of age) and after visual maturation (AVM).

RESULTS

A minimum of 6 months and average of 1.8 years follow up is reported on 262 procedures in 255 patients with an average age of 37 between January 1991 and January 1996. Sixty-two percent of patients had their strabismus onset BVM. Fifty-one percent of BVM patients and 80% of AVM patients had incomitant deviations. Adjustable suture surgery was performed on 97% of all patients, with 28% of BVM and 57% of AVM patients having multiplanar surgery. Successful motor alignment was achieved in 85% of all patients after one surgical procedure. Sensory success was achieved in 81% of all AVM patients and 25% of all BVM patients. Subjective success was 94% in both groups of patients.

CONCLUSIONS

Numerous differences exist between childhood and adult strabismus characteristics and response to surgery. Although strabismus surgery is effective, differences in results reflect the varied physiology regarding etiology, pathophysiology, and symptomology. Classification into AVM and BVM groups will provide continued clarity for future studies.

Ocular manifestations of genetic and developmental diseases

Ophthalmic genetics is a rapidly expanding field that includes both clinical and basic sciences. Clinical descriptions of syndromes and new diagnostic testing both reflect the increase in knowledge and technology of molecular biology. Technologic advances have resulted in old diseases being described in new ways and being attributed to new pathophysiologic mechanisms. This review is intended to update the past year's contributions in ophthalmic genetics. Discussion is by disease type, which is familiar to most clinicians.

Comitant esodeviation resulting from neurologic insult in children

PURPOSE

Our purpose was to establish whether comitance was a common or uncommon finding in children with esodeviation associated with a neurologic insult.

METHODS

A retrospective chart review was performed of children with acquired esodeviation associated with an identifiable neurologic insult.

RESULTS

Examinations of 30 children seen over a 2-year period were analyzed. Twenty-two (73%) had brain tumors. Twelve (40%) had comitant esodeviation, and the other 18 (60%) had incomitant measurements. Of the patients with comitant esodeviation, 6 had normal abduction OU (two after recovery from bilateral sixth nerve palsies), and 6 had mild or minimal abduction deficits. Moderate or severe abduction deficits were associated with incomitant measurements.

CONCLUSIONS

Comitant esodeviation can be common in children with identifiable neurologic insults.

Successful visual rehabilitation after neonatal penetrating keratoplasty

BACKGROUND

Penetrating keratoplasty in infancy and childhood has traditionally met with limited visual success due to a combination of unique physiology and technical problems in this patient population. With the advances in microsurgical instrumentation, corneal preservation, and visual developmental physiology ophthalmologists are finding increasing indications for penetrating keratoplasty in the childhood population. The long term results of neonatal penetrating keratoplasty in two patients with unilateral congenital corneal opacification are reported.

METHODS

Penetrating keratoplasty was performed on one eye in each of two infants within the first 3 weeks of life. Amblyopia treatment and optical therapy have been continued since surgery.

RESULTS

After 6 years both grafts have remained clear. One patient developed the infantile esotropia syndrome. Visual development using Snellen optotypes is age normal for both transplanted eyes.

CONCLUSIONS

Penetrating keratoplasty when combined with optical correction and amblyopia therapy may restore and preserve vision in selected patients with congenital corneal opacification if performed in the neonatal period.

Adjustable horizontal rectus recession surgery for disparate distance-near ocular deviations

Strabismic deviations which display incomitance changing from distance fixation to near fixation are the result of many disturbances of both the supranuclear and infranuclear ocular motor system. This report details the surgical treatment and outcome of 6 patients with disparate distance-near deviations due to different etiologies. The surgical procedure involves recessing all four horizontal recti on both eyes using the adjustable suture technique. The approach to surgery consisted of operating on the vergence angle with the larger deviation with a bilateral lateral rectus recession (BLREC) or a bilateral medial rectus recession (BMREC) and simultaneously operating on the smaller vergence angle, treating the total induced deviation with the bilateral recession not used first (remaining BLREC or BMREC). All patients had a significant decrease in their distance-near disparity, increased horizontal comitance, normalization of their accommodative convergence to accommodation ratios, and resolution of diplopia. A four horizontal recti muscle, adjustable suture recession is another technique that can be added to the treatment regimens for distance-near disparity strabismic syndromes.

Ocular manifestations of genetic and developmental diseases

Although ophthalmic involvement in developmental and genetic abnormalities has been recognized for centuries, it is only recently, due to new discoveries in molecular biology, that our classification and pathophysiology of congenital eye diseases have been advanced. In the next few years these advances will increasingly influence aspects of diagnosis classification, and therapy in ophthalmology. Tests for acquired and inherited diseases in opthalmology are being revolutionized by biotechnical innovations. The molecular genetics of ocular diseases is currently undergoing changes in classification due to intense investigations using advanced biotechnology. The potential for new treatment modalities, such as gene therapy, for molecular eye diseases, once thought to be pure fiction, is now a reality. This paper will outline recent changes in classification, organization, and general knowledge regarding inherited eye diseases.

Visually impaired children with sensory defect nystagmus, normal appearing fundi and normal ERGS

The differentiation of congenital motor nystagmus (CMN) from sensory defect nystagmus (SDN) in early life is a common diagnostic problem, since their wave forms are indistinguishable. A diagnosis of SDN is made when fundal or ERG abnormalities are present. CMN is generally diagnosed by exclusion. This approach can lead to late or incorrect diagnosis, and to the overlooking of important genetic implications. In addition, the classification of congenital nystagmus into pure motor and sensory types is inadequate. The authors present case reports illustrating this problem and suggest strict criteria for a diagnosis of CMN. They also point out that a miscellaneous group of rare disorders of the macula tend to be overlooked and misdiagnosed.

The use of hyaluronic acid during adjustable suture surgery

We prospectively studied the force required to move an extraocular muscle after adjustable suture surgery with and without the perioperative use of hyaluronic acid (Healon). The 15 muscles that received hyaluronic acid averaged 15.0 g of force to move the muscle 2.0 mm which was significantly different than the average force of 36.15 g required for the 13 control muscles. The decreased force required to adjust the muscle along with potential antiinflammatory properties of hyaluronic acid make this a useful adjunct during adjustable suture surgery.

Hypopyon uveitis in patients with acquired immunodeficiency syndrome treated for systemic Mycobacterium avium complex infection with rifabutin

OBJECTIVE

Iridocyclitis has been identified as a dosage-dependent side effect in patients with the acquired immunodeficiency syndrome (AIDS) who are treated for Mycobacterium avium complex (MAC) infection with systemic rifabutin. We reviewed cases of acute hypopyon uveitis occurring in patients with AIDS to establish whether there was an association.

DESIGN

Retrospective case series.

SETTING

Outpatient clinic and inpatient hospital-based ophthalmology referral practice and infectious disease specialty service.

PATIENTS

Seven patients with AIDS, aged 10 to 40 years, presenting with acute unilateral hypopyon mimicking infectious endophthalmitis.

MAIN OUTCOME MEASURES

Findings from complete ophthalmological evaluation and ancillary laboratory testing.

RESULTS

At the time of presentation, all seven patients were receiving treatment for MAC infection with rifabutin (dosage range, 300 to 600 mg/d) and clarithromycin. Results of microbiological investigations in five patients were negative. Iridocyclitis became bilateral in all seven patients, and hypopyon developed in the contralateral eye in five of seven patients. Hypopyon resolved rapidly with intensive topical corticosteroid therapy. Residual inflammation responded to topical corticosteroids with or without reduction of the rifabutin dosage.

CONCLUSIONS

Concomitant use of rifabutin, clarithromycin, and fluconazole may precipitate hypopyon uveitis in patients with AIDS being treated for MAC infection.

Application of the potassium-titanyl-phosphate laser during extraocular muscle surgery: technique and histopathology

We determined laser parameters and delivery system requirements for successful use of the potassium-titanyl-phosphate (KTP) laser for strabismus surgery and its histopathologic effect on extraocular muscle, tendon, sclera, and cornea of human and rabbit eyes. Enucleated cadaver eyes and exenterated rabbit orbital contents were used. Using a 200-microns fiberoptic tip delivery system, varying laser energies were used to perform muscle insertion site and corneal damage, tenotomies, and myotomies. Pulse durations of 0.5 second and energies above 0.8 watt were needed for tenotomy or myotomy. No damage to the surrounding tissues or sclera was observed with laser tenotomy or myotomy performed 0.5 mm from the insertion site. Energy above 0.8 watt applied directly caused full thickness disruption. In comparison to scissor myotomy, the laser provided charring of the superficial tissues. This study shows that the KTP laser can be safely and accurately used for extraocular muscle tenotomy or myotomy.

The visual-evoked response in infants with central visual impairment

We studied ten children with central visual impairment with a known neurologic defect and an abnormal visual-evoked response who had results of repeat electrophysiologic testing evaluated at the Children's Hospital of Philadelphia from December 1989 through July 1991. Central visual impairment is defined as poor visual function with a normal anterior visual pathway. Age at first examination ranged from 5 to 48 months with a followup of two to 31 months. Repeat visual-evoked response testing showed improvement in seven patients and no change in three. Grating acuity as measured by the Teller acuity card procedure, performed in nine of ten patients, improved in seven, showed no change in one, and declined in one. We found a potentially favorable prognosis for those infants with central visual impairment, despite an initially abnormal visual-evoked response. We used a clinical approach to this disorder to improve diagnostic categorization and prognostic capabilities in central visual impairment.

Ophthalmic features and visual prognosis in the Treacher-Collins syndrome

The ocular findings and visual prognosis were reviewed in 24 patients with the Treacher-Collins syndrome who were evaluated in the craniofacial clinic in the Division of Pediatric Ophthalmology at Children's Hospital of Philadelphia between 1980 and 1991. All patients had some abnormality. Vision loss was present in 37% of patients. Amblyopia was present in 33%, significant refractive errors were present in 58%, and anisometropia was documented in 17%. Strabismus was present in 37% and significant lid and adnexal abnormalities were seen in 96%. The prognosis for normal vision in at least one eye is good but vision loss secondary to amblyopia is more resistant to treatment owing to other medical problems and social concerns.

The intraoperative oculocardiac reflex as a predictor of postoperative vaso-vagal responses during adjustable suture surgery

Adjustable suture surgery has become a popular method of strabismus correction in those cases in which results are less predictable, such as reoperations, thyroid ophthalmopathy, and blind eyes. Complications related to adjustable strabismus surgery are, in general, no different than those related to standard surgical techniques. We noticed a subgroup of patients who experienced significant vaso-vagal responses (V-VR) during postoperative adjustment and sought to discover a method of identifying these patients prior to adjustment. Sixty patients were studied prospectively from July 1991 to July 1992. All patients had surgery under general anesthesia and were adjusted 24 hours later. A positive oculocardiac reflex (OCR) occurred when a 10% or greater intraoperative change in heart rate was associated with traction on an extraocular muscle. A positive V-VR postoperatively consisted of one or more subjective findings (dizziness, light-headedness, nausea, or body temperature changes), and two or more objective findings (10% or greater change in heart rate, hypotension, pallor, diaphoresis, vomiting, disorientation, or loss of consciousness). Variables studied for predictive value included OCR, age, sex, strabismus type, previous surgery, muscle adjusted, and systemic disease. Twenty-five patients (41.6%) had a positive V-VR during adjustment. Twenty-seven patients (45%) had a positive OCR. Eighty-five percent of patients with a positive OCR and 9% of patients with a negative OCR had a positive V-VR. Younger patients were also more likely to have a positive V-VR. A positive intraoperative OCR under general anesthesia during strabismus surgery is highly predictive of a postoperative V-VR during planned adjustment.

Insertion site dynamics and histology in a rabbit model after conventional or suspension rectus recession combined with ipsilateral antagonist resection

We have used a rabbit model to study insertion movement, rotational forces, disinsertion forces, and histology of the surgically created insertion site after recession of the inferior rectus (IR) using a conventional (CONV) or suspension (SUS) technique combined with an ipsilateral superior rectus (SR) resection. During the 5-week observation period, the CONV and SUS recessed IR showed an initial posterior movement followed by an anterior movement while all resected SR had an initial posterior movement which remained stable. SR rotational forces increased and IR remained constant throughout the 5-week observation period. There were no rotation force differences between the SUS and CONV recession techniques. Disinsertion forces showed an initial large decrease in force followed by a gradual increase to preoperative levels by 3 postoperative weeks. Disinsertion force differences between the CONV and SUS recessions were observed for 5 weeks after surgery. Histologic analysis showed a delayed inflammatory response on the SUS recession compared to the CONV recession and at the middle of the insertion compared to the poles which was minimized by 3 weeks after surgery.

Congenital unilateral fibrosis, blepharoptosis, and enophthalmos syndrome

The authors report four cases of the rarest form of the congenital fibrosis syndrome. This disorder is exhibited in infancy as unilateral blepharoptosis, strabismus, limited ductions, globe displacement (enophthalmos and blepharoptosis), and decreased vision, usually due to amblyopia. Forced ductions are positive and surgical exploration confirms anomalous muscle structure. Computed tomography and magnetic resonance imaging studies in these four patients were diagnostically beneficial, showing extraocular muscle and tendinous insertion involvement, and poorly defined intraconal and extraconal masses that had the appearance of scar or inflammatory tissue. All patients had globe displacement. The opposite eye and intracranial contents were normal in all of our patients. Results of histopathologic examination obtained at surgery in three of these patients show replacement of affected structures by fibrous tissue and included the extraocular muscles, orbital fat, Tenon's capsule, and conjunctiva.

Ocular and adnexal findings in patients with facial microsomias

The authors reviewed the ocular findings in 49 patients with facial microsomias not considered part of a known syndrome. Five patients had bifacial microsomia, and 44 patients had hemifacial microsomia. These patients were evaluated in the Craniofacial Clinic in the Division of Pediatric Ophthalmology at Children's Hospital of Philadelphia between the years 1979 and 1989. Ocular or adnexal abnormalities were present in 67% of patients. Visual loss was present in 8% of eyes. Amblyopia was present in 16% of patients. Significant refractive errors were present in 27% of patients, and anisometropia was documented in 8%. Strabismus was present in 22% of patients, and significant lid and adnexal abnormalities were seen in 41%. Because ocular or adnexal findings present in a significant percentage of patients with more mild forms of facial microsomias, regular examinations to uncover and treat these abnormalities are recommended.

Epibulbar squamous cell carcinomas in brothers with Xeroderma pigmentosa

We report two brothers aged 6.6 and 5 years old with the De Sanctis-Cacchione variant of Xeroderma Pigmentosa. They had typically severe skin, and ocular and neurologic involvement. Both had epibulbar squamous cell carcinomas. The oldest presented with a large, invasive, epibulbar mass of the left eye which required enucleation. He also had an invasive squamous cell carcinoma of the right lower lid. The younger brother presented with a smaller papillomatous lesion at the medial limbus of the right eye. After removal, this was found to be squamous cell carcinoma in-situ. Flow cytometry done on the tumors revealed diploidy. The case descriptions, histopathology, and discussion of ocular manifestations are presented.