Richard W. Hertle

Computerized method of visual acuity testing: Adaptation of the Amblyopia Treatment Study visual acuity testing protocol

PURPOSEnTo report a computerized method for determining visual acuity in children using the Amblyopia Treatment Study visual acuity testing protocol.nnnMETHODSnA 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.nnnRESULTSnTest-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.nnnCONCLUSIONSnWe 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.

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

PURPOSEnHuman 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.nnnMETHODSnAn 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.nnnRESULTSnThe 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.nnnCONCLUSIONSnSevering 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.

PURPOSEnThe 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.nnnBACKGROUNDnThe 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.nnnMETHODSnForty-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.nnnRESULTSnPatient 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.nnnCONCLUSIONSnCommon 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.

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, Tenons capsule, and conjunctiva.

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.

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

BACKGROUND AND PURPOSEnWe 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.nnnMETHODSnThe 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.nnnRESULTSnThirty-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.nnnCONCLUSIONSnThe 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.

Sino-orbital-cerebral aspergillosis in immunocompromised pediatric patients.

In the immunocompetent host, aspergillosis of the nose and paranasal sinuses presents as a chronic sinusitis or as an isolated aspergilloma. This infection seldom involves the orbit in immunocompetent patients, and it is responsive to surgical debridement and antifungal therapy. By comparison invasive aspergillosis of the paranasal sinuses in immunocompromised hosts commonly extends into the orbit and brain. This infection has been reported in adults with an underlying malignancy and, more recently, in adult patients with HIV infection. Invasive aspergillosis of the paranasal sinuses also occurs in immunosuppressed children, but orbital and intracerebral involvement is uncommon 10 and has not been previously reported in children with HIV infection. Herein we present three cases of sino-orbital-cerebral aspergillosis occurring in immunocompromised children, two of whom had HIV infection. We further examine the predisposing factors, clinical presentation, radiologic characteristics, clinical course and histopathologic features of sino-orbital-cerebral aspergillosis in these children and those reported in the literature.

Ocular and Adnexal Findings in Patients with Facial Mierosomias

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 Childrens 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.

Effects of tenotomy surgery on congenital nystagmus waveforms in adult patients. Part I. Wavelet spectral analysis

Congenital nystagmus (CN) is an aperiodic oscillatory eye movement disorder. Horizontal rectus tenotomy with simple re-attachment has been proposed as a therapy for CN. This therapy might affect vision and/or eye movements. Another paper deals with improvements in visual acuity. This and the companion paper examine changes in eye movements. In this study, we examined the effect of tenotomy on nystagmus waveforms using wavelet spectral analysis. No common effect was found across the patients on the wavelet spectra of the CN beat, suggesting that tenotomy surgery has no effect, or only a quite small effect, on the waveform structure of CN.

EFFECTS OF TENOTOMY SURGERY ON CONGENITAL NYSTAGMUS WAVEFORMS IN ADULT PATIENTS. PART II. DYNAMICAL SYSTEMS ANALYSIS

Congenital nystagmus (CN) is an aperiodic oscillatory eye movement disorder of unknown etiology. We examined the effect of horizontal rectus tenotomy with simple re-attachment on the dimensionality of the dynamical mechanism underlying CN. The correlation dimensions (CDs) were calculated from eight patients who had tenotomy surgery. We found no significant differences in the CDs that could be associated with the surgery. The change in dimensionality was less than 5% on average. The results suggest that the tenotomy has no effect, or only a quite small effect, on the underlying mechanism of the CN beats.