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OBJECTIVES: To determine if confocal scanning laser (CSL) tomography can quantify optic disc topography in patients with pseudopapilledema (PP) and to contrast the regional topography of the optic disc in PP and pseudotumor cerebri (PTC). MATERIALS AND METHODS: Three-dimensional optic disc images from 10 PP patients PP and 17 PTC patients were obtained using the Heidelberg Retinal Tomograph (HRT). Two conventional HRT parameters, volume above the reference plane and volume above the surface, were used to quantify global disc elevation. In addition, local topography was determined at 100 microm intervals along eight meridians at 100 to 1700 microm from the disc center. The global and local measures of disc topography in the two groups were compared statistically. RESULTS: Significant between group differences were detected for both global measures. Regional analysis revealed vertical symmetry and horizontal asymmetry in PP and PTC as well as significant between group differences in peripapillary height. CONCLUSIONS: CSL tomography can quantify disc elevation in both PP and PTC and may be useful for differentiating disc morphology in PP and PTC. The volume of the disc above the retinal surface is greater in PTC than in PP. However, most of the difference in elevation between the two groups occurs over the disc rim and peripapillary retina.

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PURPOSE: To investigate sensory fusion responses in infants and children with early-onset esotropia to gain insights into the sequence of events that leads to strabismus. METHODS: Sensory fusion was tested by measuring visual evoked potential (VEP) responses to dynamic random dot correlograms (DRDCs) in a group of children (n = 23) with early-onset esotropia. Thirteen children were tested before surgical alignment, and 13 children were tested after surgical alignment (three children were tested before and after surgery). If the angle of strabismus was larger than 5 prism diopters, it was corrected with Fresnel prisms (Fresnel Prism and Lens, Scottsdale, AZ). RESULTS: Five (38%) of the 13 children who were tested before surgery showed detectable VEP responses to correlogram stimuli compared with 11 (85%) of the 13 children who were tested after surgical alignment. There were no significant statistical differences between VEP responses to DRDCs from the postsurgery group and VEP responses from an age-matched control group with normal binocular vision. CONCLUSIONS: The presence of cortical sensory fusion in children with early-onset esotropia suggests that a congenital defect of sensory fusion cannot be the root cause of esotropia in most children. The data suggest that sensory fusion, when measured by VEP responses to DRDCs, is more robust than stereopsis to abnormal binocular experience and support the notion that pathways processing correlated/anticorrelated stimuli may not completely overlap with pathways processing disparity information.

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Visual evoked potentials to pattern reversal (PR-VEPs) are used to assess the integrity and maturation of the visual pathways in infants and young children. To establish normal ranges and to facilitate interpolation, we consider the maturation rate of PR-VEPs using published normative data. Curves based on the logistic function (a sigmoid model) are introduced and compared with three other models: (1) the power law function; (2) the sum of two decaying exponentials; and (3) a two-stage linear model. Although methods vary somewhat, remarkable consistency among laboratories is found for the maturation of the major positivity (P1) of PR-VEP. The P1 occurs at approximately 260 ms in neonates and is quite variable. It matures rapidly before 12-14 weeks of age and becomes much less variable. The logistic model provides a parsimonious description of P1 maturation with most rapid maturation at around 6 weeks of age for large patterns and around 9 weeks for small patterns. As inter-laboratory agreement is generally good, the normal ranges based on this model could be used in centres, which do not have their own normative databases for infant VEPs.

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PURPOSE: To determine the feasibility of adapting confocal scanning laser (CSL) tomography of the optic disc for quantitative evaluation of papilledema in pseudotumor cerebri (PTC). METHODS: Confocal scanning laser tomography of the optic disc was performed in 11 patients with diagnosed PTC and 12 visually normal control subjects of similar age. In five patients with active papilledema, CSL tomography was performed serially over several months. To quantify optic disc characteristics, surface topography was measured in 0.1-mm steps along the horizontal and vertical meridians and four oblique meridians. Best fit polynomial functions, describing surface topography along each meridian, were derived using linear regression analysis. RESULTS: Third-order polynomials provided excellent fits (significantly better than the second-order functions) to the surface topography for all meridians in the control subjects and patients with PTC. In control subjects and PTC patients an asymmetry in the slope of the optic disc contours was evident along the horizontal but not the vertical meridian. In patients with active papilledema a significant elevation of the center of the disc was accompanied by a change in overall surface topography. Each of the PTC patients followed up serially had a pronounced posterior deformation of the disc (i.e., a reduction in papilledema) that was initially apparent in the temporal meridian and did not proceed uniformly across all meridians. CONCLUSIONS: Confocal scanning laser tomography can quantify the magnitude and monitor the resolution of papilledema in PTC. Studies of optic nerve head topography may provide further insight into optic nerve compliance with elevated intracranial pressure.

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OBJECTIVE: To describe the pattern reversal visual evoked potentials (VEPs) that were used to monitor and quantify early visual development following treatment for dense, unilateral, congenital cataract. DESIGN: Longitudinal prospective study. PATIENTS: Six infants who underwent surgery and contact lens correction before age 5 months and who had good compliance with occlusion therapy throughout the first 3 years of life. RESULTS: Initially, VEPs from aphakic eyes showed marked abnormalities, including small amplitudes, prolonged latencies, missing components, and absent VEPs to small check sizes. Threshold check size was elevated by 3 octaves or more. With part-time occlusion of the opposite eye, VEPs normalized rapidly in the first year, but residual deficits remained to age 4 years when visual acuities were between 20/50 and 20/120 in aphakic eyes. Threshold check size clearly differentiated between aphakic and normal eyes and was the only VEP parameter that was correlated with single-letter visual acuity. Thus, threshold check size had greater clinical use than measures of pattern VEPs based on latency, amplitude, or waveform. CONCLUSIONS: Patients treated for unilateral congenital cataract, who have early surgery and contact lens correction and comply with occlusion therapy, show a period of rapid VEP maturation and have a good visual prognosis.

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Visual evoked potentials (VEPs), that provide unequivocal objective evidence of cortical binocularity have been recorded from adults and young infants using a new VEP system developed for this purpose. The system uses alternating field stereoscopy (AFS) to present separate visual stimuli to each eye. With this system, the binocular image pairs to the right and left eyes alternate at a high rate on a single video monitor. The subject wears spectacles incorporating light-scattering liquid crystal lenses which alternate electronically between opaque and clear modes in synchrony with the video monitor. To detect cortical binocularity, the system analyzes VEP activity mathematically and identifies significant responses at test frequencies reflecting binocular cortical interactions exclusively. Three types of binocular stimuli were presented: (1) dynamic random dot correlograms (correlograms); (2) dynamic random dot stereograms (stereograms); and (3) dichoptic checkerboard stimuli. The correlograms are generated when moving random dot patterns presented to each eye alternate between two phases, correlated and anticorrelated. With the stereograms, portions of random dot patterns presented to each eye are shifted horizontally relative to each other at a fixed rate, alternately producing crossed and uncrossed binocular disparities. Subjectively, these patterns appear to shift in depth. Dichoptic checkerboard stimuli are regular checkerboard patterns which reverse at different rates (frequencies) for each eye. Binocular VEPs are generated due to cortical interactions at the difference (beat) frequency. Using this VEP system, we have recorded binocular VEPs from 10 normal adults and more than 40 infant subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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Pattern visual evoked potentials (P-VEPs) were recorded in 161 human infants who were between 3 weeks and 2 yr of age. The latency of the first reproducible positive peak in the P-VEP was measured monocularly and binocularly for five sizes of phase alterations checkerboard stimuli (range: 120' to 7.5' check widths). Rapid visual maturation in the first 6 months of life was shown by the development of reproducible P-VEPs to smaller check sizes and by a rapid decrease in the latency of the first reproducible positive peak. Monocular P-VEPs have slightly longer latencies than the binocular P-VEPs. This latency difference is invariant with age, but is significantly greater with larger check stimuli. Normal ranges for this large population are provided as a reference for clinical studies.

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A case of primary Ewing's sarcoma of the orbit and paranasal sinuses in a 6-yearold boy is reported. The child presented with headaches and unilateral visual loss. Loss of vision as a result of optic nerve involvement with primary Ewing's sarcoma is extremely rare.

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We have documented visual and auditory neurotoxicity in 42 of 89 patients with transfusion-dependent anemia who were receiving iron chelation therapy with subcutaneous deferoxamine (DFO). Of the affected groups, 13 presented with visual loss or deafness or both, and ophthalmologic, audiologic, and visual evoked potential studies (VEPs) uncovered abnormalities in 29 more. Four patients with visual loss had optic neuropathy with a marked decrease in acuity and loss of color vision. These 4, and 16 other asymptomatic patients, had abnormal VEPs. When DFO was stopped, 3 of 4 with visual problems regained normal visual function but VEPs remained abnormal. Of the other 16 with abnormal VEPs, 9 became normal or improved and 7 did not change; on restarting DFO, the 9 became abnormal again. There were 22 abnormal audiograms that showed a high-frequency sensorineural deficit; 13 patients were symptomatic and 4 needed hearing aids. On stopping DFO, 9 became asymptomatic but 15 audiograms remained abnormal and 2 deteriorated further on restarting the drug. An analysis of the clinical data showed that members of the affected group were younger, had lower serum ferritin values, and were self-administering higher doses of DFO/kg body weight. Significantly lower doses of DFO were being taken by patients without abnormalities than by those with visual symptoms, abnormal audiograms, or prolonged VEPs (P less than 0.001, less than 0.006, and less than 0.04, respectively). The data implicate high-dose DFO as a central factor in the pathogenesis of the neurotoxicity. Our serial studies provide the basis for effective yet safe DFO administration for patients who require the agent.

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As deferoxamine (DFO) appeared to have certain toxic effects on the sensory pathways in some of our patients on nightly subcutaneous deferoxamine (DFO) for transfusion-dependent anemia, treatment was stopped in all of these patients to obtain a comprehensive baseline assessment of sensory function. Visual evoked potentials (VEPs) were studied in all patients; the 77 described in this report all had normal ophthalmological examinations. Abnormally prolonged VEP latencies were found in 21%. The patients remained off DFO for 2-6 months, and most of those with abnormal VEPs who were retested showed improvement in their VEPs over this period with the VEPs returning to within normal range in half the cases; two showed no change. Since restarting DFO, VEP latencies in 10 of these patients have increased again beyond normal limits, as have the VEPs in 7 who had previously normal VEPs. Although most of the 77 patients have VEPs that are currently normal and stable while on DFO, a significant sub-group have abnormal VEPs that appear sensitive to the administration of DFO and may reflect a vulnerability to DFO neurotoxicity. These data suggest that the VEPs can detect subclinical toxic effects of DFO on the visual system and should be considered as a monitor for patients receiving chronic DFO therapy.

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Of 89 patients receiving nightly subcutaneous deferoxamine for transfusion-dependent thalassemia major or Diamond-Blackfan anemia, 13 presented with visual loss or deafness of acute onset or both. Detailed ophthalmologic, audiologic, and evoked-potential studies uncovered abnormalities caused by neurotoxicity in 27 more. Four patients with visual loss had optic neuropathy, with a marked decrease in acuity, loss of color vision, and delayed visual evoked potentials. Five asymptomatic patients had changes in the pigment of the retinal epithelium. The hearing loss was characterized by a high-frequency sensorineural deficit, which necessitated hearing aids in six patients. When deferoxamine was stopped, recovery of vision was complete in 2 patients and partial in 2, and in 22 patients with abnormal audiograms, reversal of the hearing deficit was complete in 4 and partial in 1. An analysis of the clinical data showed that members of the affected group were younger, had lower serum ferritin values, and were self-administering higher doses of deferoxamine per kilogram of body weight. Significantly lower doses of deferoxamine were being taken by patients without abnormalities than by those with visual symptoms, abnormal audiograms, or prolonged evoked potentials (P less than 0.001, less than 0.006, and less than 0.04, respectively). The data implicate high-dose deferoxamine as a central factor in the pathogenesis of the neurotoxicity. We strongly recommend careful regulation of the deferoxamine dosage and serial audiovisual monitoring in all patients receiving the drug.

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Contrast sensitivity measurements were obtained from 64 patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus who had normal Snellen acuity and minimal or no visible diabetic retinopathy. Contrast thresholds were determined for stationary gratings at six spatial frequencies, ranging from 0.5 to 22.8 cycles/degree (c/deg), and for 1.0-c/deg gratings phase-alternated at 15 Hz. Data from each group of diabetic patients were compared with data from age-matched normal subjects. We found that (1) patients with IDDM and no retinopathy had normal contrast sensitivity, (2) patients with NIDDM and no retinopathy had abnormal contrast sensitivity at only one spatial frequency (22.8 c/deg), and (3) patients with NIDDM and background retinopathy had abnormal contrast sensitivity at all spatial frequencies tested. We also found a dissociation of Snellen acuity and contrast sensitivity, indicating that contrast sensitivity can be used as an early index of changes in the retina not demonstrated by measurements of visual acuity.

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A 60-year-old man fell; a subdural hematoma developed and he lost consciousness. Visual evoked potentials demonstrated a total conduction block in the left optic nerve and slowed conduction on stimulation of the right eye. He died four weeks later, and necropsy showed focal infarcts in the intracranial portion of both optic nerves.

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Optic nerve hypoplasia is frequently associated with congenital CNS anomalies and endocrine disturbances. In a prospective study of 93 children with this condition, we found that 78% of those with bilateral involvement, poor vision, and nystagmus (group 1) had additional nonocular developmental abnormalities. In contrast, among children with unilateral optic nerve hypoplasia (group 2) or with bilateral segmental hypoplasia and good vision (group 3), only 21% had nonocular developmental disturbances. Delayed development in 23 children was the most frequent nonvisual problem associated with optic nerve hypoplasia, and in five cases it occurred in the absence of detectable CNS, endocrine, or medical abnormalities. Nine patients had decreased levels of thyroid hormone; three, decreased levels of growth hormone; and three, decreased levels of both. Five had histories of neonatal hypoglycemia. Of the children with endocrine disturbances, ten had delayed development, but only seven had anomalies on computed tomographic scan.

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It has been suggested that the pupillary response to hydroxyamphetamine hydrobromide eyedrops will separate distal from proximal lesions of the sympathetic pathway from the brain to the eye (the pupil fails to dilate in postganglionic lesions). We studied the pupillary response to hydroxyamphetamine in two groups of rabbits with surgically produced Horner's syndrome. Rabbits in one group had postganglionic lesions. In all animals, a miotic pupil developed ipsilateral to the surgical lesion, and oculosympathetic paresis was confirmed in each by testing pupillary response to topically applied cocaine. In rabbits with postganglionic lesions, hydroxyamphetamine failed to dilate the miotic (Horner's) pupils as well as it dilated the normal pupils, while in rabbits with preganglionic lesions both miotic and normal pupils dilated equally. Hydroxyamphetamine appears to be a diagnostically useful drug in Horner's syndrome.

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