Faculty Bibliography

PURPOSE: To introduce a rapid and objective electrophysiological technique that can assess visual function in the magnocellular pathway, which is thought to be affected in early-stage glaucoma. METHODS: Low-contrast bright or dark isolated-checks were luminance-modulated against a static background at 10 Hz in order to drive preferentially the magnocellular ON or OFF pathway. Visual evoked potentials were recorded during 1-s epochs of stimulation and responses at the stimulus frequency were measured. Artifact rejection features ensured that eight valid runs were obtained per eye. Signal-to-noise ratios (SNR) were derived based on a multivariate statistic. In order to demonstrate its functionality, a small group of patients with glaucoma (N = 18, Snellen acuity of 20/30 or better) and control observers (N = 16) were tested. A participant failed the test if either eye yielded an SNR < or = 1. Receiver-operating-characteristic curve analysis was used to estimate the accuracy of group classification. RESULTS: The instrument was found to elicit reliable responses from control observers. For the 15% bright condition, all control observers yielded significant isolated-check VEPs (icVEPs), whereas the majority of patients failed to do so, indicating significant losses in central visual function. This condition produced the highest classification accuracy (94%), followed by the 10% dark condition (91%). CONCLUSIONS: Both ON and OFF divisions of the magnocellular pathway can be assessed rapidly through the application of the icVEP technique. This measure of central visual function may be of value in the detection of glaucomatous deficits and may complement tests of peripheral function

PURPOSE:: To investigate the location and fixation stability of preferred retinal locations (PRLs) in patients with macular disease, and the relationship among areas of abnormal fundus autofluorescence, the PRL and visual sensitivity. METHODS:: Fifteen patients (15 eyes) were studied. Seven had Stargardt disease, 1 bull's eye maculopathy, 5 age-related macular degeneration, 1 Best disease, and 1 pattern dystrophy. All tested eyes had areas of abnormal fundus autofluorescence. The PRL was evaluated with fundus photography and the Nidek microperimeter. Visual field sensitivity was measured with the Nidek microperimeter. RESULTS:: Of the 15 eyes, 4 had foveal and 11 had eccentric fixation. Eccentric PRLs were above the atrophic lesion and their stability did not depend on the degree of eccentricity from the fovea. Visual sensitivity was markedly decreased in locations corresponding to hypofluorescent areas. Sensitivity was not decreased in hyperfluorescent areas corresponding to flecks but was decreased if hyperfluorescence was in the form of dense annuli. CONCLUSION:: Eccentric PRLs were in the superior retina in regions of normal fundus autofluorescence. Fixation stability was not correlated with the degree of eccentricity from the fovea. To assess the outcomes of treatment trials it is important to use methods that relate retinal morphology to visual function

PURPOSE: To compare conventional visual evoked potential (cVEP) and multifocal visual evoked potential (mfVEP) methods in patients with optic neuritis/multiple sclerosis (ON/MS). METHODS: mfVEPs and cVEPs were obtained from eyes of the 19 patients with multiple sclerosis confirmed on MRI scans, and from eyes of 40 normal controls. For the mfVEP, the display was a pattern-reversal dartboard array, 48 degrees in diameter, which contained 60 sectors. Monocular cVEPs were obtained using a checkerboard stimulus with check sizes of 15' and 60'. For the cVEP, the latency of P100 for both check sizes were measured, while for the mfVEP, the mean latency, percent of locations with abnormal latency, and clusters of contiguous abnormal locations were obtained. RESULTS: For a specificity of 95%, the mfVEP(interocular cluster criterion) showed the highest sensitivity (89.5%) of the 5 monocular or interocular tests. Similarly, when a combined monocular/interocular criterion was employed, the mfVEP(cluster criterion) had the highest sensitivity (94.7%)/specificity (90%), missing only one patient. The combined monocular/interocular cVEP(60') test had a sensitivity (84.2%)/specificity (90%), missing 3 patients, 2 more than did the monocular/interocular mfVEP(cluster) test. CONCLUSION: As the cVEP is more readily available and currently a shorter test, it should be used to screen patients for ON/MS with mfVEP testing added when the cVEP test is negative and the damage is local

PURPOSE: To assess the normal variations in retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT). SUBJECTS AND METHODS: Both eyes of 48 individuals (age 56.4+/-9.5 y) with normal vision and refractive errors between +/-6.0 D were tested with the fast RNFL scan protocol of the OCT3 (Zeiss Meditech). Their 256-point RNFL profiles were exported for analysis. The location and peak amplitude of the maxima of the RNFL profiles were measured. Intersubject and interocular variations were assessed with a coefficient of determination, R2. An R2 of 1.0 indicated that the average profile from all 48 individuals (or of the 2 eyes) accounted for 100% of the variation of an individual eye's profile. RESULTS: The R2 for the interocular comparison was good, with averages of 0.91+/-0.07 (right eye) and 0.92+/-0.05 (left eye). The R2 for the comparison of the individual's profile to the mean group profile was only 0.61+/-0.29 (right eye) and 0.65+/-0.24 (left eye), with 27% of the R2 values below 0.5. Even after normalizing each individual's profile by its mean, R2 was only 0.75+/-0.16 (0.75+/-0.16) for the right (left) eye. The location of the peaks for the right (left) eye ranged over 91 degrees (88 degrees) for the superior peak and over 64 degrees (66 degrees) for the inferior peak. The range of peak amplitudes for the right (left) eye spanned a factor of 1.7 (1.8) and 2.0 (1.7) for the superior and inferior peaks, respectively. CONCLUSIONS: There was a wide variation in the amplitude and shape of the individual RNFL profiles. However, the RNFL profiles of the 2 eyes of an individual were extremely similar. Adding an interocular comparison with OCT RNFL tests should help identify some false positives

PURPOSE: The presence or absence of functional changes associated with solitary, congenital, hypopigmented lesions of the retinal pigment epithelium (RPE) have been a matter of controversy. This case report describes retinal and functional findings in a young patient with such a lesion. METHODS: A 10-year-old Hispanic female with a solitary congential hypopigmented spot of the RPE was examined using fundus photography, fluorescein angiography, autofluorescence imaging (AF) and optical coherence tomography (OCT). Functional analyses were performed using the Humphrey 24 - 2 visual field, Goldmann perimetry and the multifocal ERG (mfERG). RESULTS: A small visual field defect was demonstrated on both Goldmann perimetry (I/ 2e test object) and on Humphrey 24 - 2 visual field testing (significant at the 0.5 % level for pattern deviation). The multifocal ERG response amplitudes were decreased in the corresponding area and increased in implicit time. Autofluorescence imaging showed an absence of fluorescence corresponding to the area of the lesion. OCT findings were indicative of a small amount of subretinal fluid or schisis-like changes overlying the RPE anomaly. CONCLUSION: The results indicate that solitary, albinotic spots of the RPE can be associated with visual field defects and outer retinal deficits; these may be related to impaired RPE function and/or chronic exudative changes

PURPOSE/OBJECTIVE:To report a case of cilioretinal artery occlusion with normal fluorescein angiography findings that was evaluated by electroretinography (ERG) and microperimetry. METHODS:A 64-year-old-man presented with an oval paracentral scotoma in the temporal field of the left eye that became more evident after cataract surgery. Fundus photography, fluorescein angiography, ERG, multifocal ERG, and microperimetry were performed. RESULTS:Multifocal ERG showed decreased signal amplitudes in areas corresponding to areas with a visual defect as detected by microperimetry. Pattern ERG also showed a defect in the P50 component. Findings of fundus photography, fluorescein angiography, and full-field ERG were within normal limits. CONCLUSION/CONCLUSIONS:This case demonstrates the possibility of using ERG and microperimetry as noninvasive tools in the diagnosis of cilioretinal artery occlusion.

AIM: To assess the accuracy of optical coherence tomography (OCT) in detecting damage to a hemifield, patients with hemifield defects confirmed on both static automated perimetry (SAP) and multifocal visual evoked potentials (mfVEP) were studied. METHODS: Eyes of 40 patients with concomitant SAP and mfVEP glaucomatous loss and 25 controls underwent OCT retinal nerve fibre layer (RNFL), mfVEP and 24-2 SAP tests. For the mfVEP and 24-2 SAP, a hemifield was defined as abnormal based upon cluster criteria. On OCT, a hemifield was considered abnormal if one of the five clock hour sectors (3 and 9 o'clock excluded) was at <1% (red) or two were at <5% (yellow). RESULTS: Seventy seven (43%) of the hemifields were abnormal on both mfVEP and SAP tests. The OCT was abnormal for 73 (95%) of these. Only 1 (1%) of the 100 hemifields of the controls was abnormal on OCT. Sensitivity/specificity (one eye per person) was 95/98%. CONCLUSIONS: The OCT RNFL test accurately detects abnormal hemifields confirmed on both subjective and objective functional tests. Identifying abnormal hemifields with a criterion of 1 red (1%) or 2 yellow (5%) clock hours may prove useful in clinical practice

OBJECTIVE: To investigate the role of structural and functional measurements in the assessment of internal limiting membrane (ILM) peeling for the treatment of eyes with macular pucker. METHODS: Ten patients with macular pucker who underwent pars plana vitrectomy with ILM peeling were studied prospectively. Visual acuity measurement, standard automated achromatic perimetry, multifocal electroretinography (mfERG), and optical coherence tomography (OCT) were performed before and 3 months after surgery. Four surgical samples obtained from similar patients were analyzed with electron microscopy. RESULTS: Three months after surgery, mean visual acuity +/- SD was significantly improved from 0.4 +/- 0.11 logMAR to 0.19 +/- 0.13 logMAR (P < or = 0.002), and mean central retinal thickness +/- SD was significantly decreased 428 +/- 73 microm to 326 +/- 34 microm (P < or = 0.002). The mfERG response amplitudes were slightly decreased in eight patients, and five of these patients also had asymptomatic decreases in visual field sensitivity. The electron micrographs revealed segments of Muller cell footplates on the retinal side of the ILM in all four specimens. CONCLUSION: In this study, the use of mfERG, OCT, and standard automated achromatic perimetry showed changes in macular function and structure postoperatively. These measures of visual function and structure allow for better evaluation of the surgical outcome and understanding of the changes that may occur after ILM peeling

PURPOSE: To investigate possible adverse effects of a yellow-tinted intraocular lens (IOL) on scotopic sensitivity and hue discrimination. SETTING: Departments of Ophthalmology, Columbia University and New York University School of Medicine, New York, New York, USA. METHODS: Nine patients with a yellow-tinted IOL in 1 eye and a colorless ultraviolet IOL in the fellow eye and 9 young phakic subjects with and without a yellow-tinted clip-on lens were tested. Hue discrimination was measured with the Farnsworth-Munsell (FM) 100-hue test. Dark-adapted thresholds to 440 nm, 500 nm, and 650 nm lights were measured at 23 locations using a modified Humphrey perimeter, and dark-adapted thresholds to white light were measured at 15 degrees temporal retina. RESULTS: In the 9 patients, there were no significant differences in dark-adapted sensitivities to 440, 500, 650 nm, or white-light stimuli and no differences in FM 100-hue error scores between eyes with yellow-tinted IOLs and those with colorless IOLs. Similarly, in young phakic subjects, there were no significant differences in FM 100-hue error scores or dark-adapted sensitivity to the white light with and without the yellow-tinted clip-on lens. However, with the clip-on lens, mean sensitivities to the 440 nm, 500 nm, and 650 nm stimuli were significantly decreased by 2.7 to 2.8 dB, 0.7 to 1.0 dB, and 0 to 1.2 dB, respectively. CONCLUSION: Results suggest that implantation of a yellow-tinted IOL has non-significant effect on scotopic sensitivity and hue discrimination

PURPOSE: To compare latencies of conventional visual evoked potentials (cVEPs) and multifocal VEPs (mfVEPs) in the same patients. Previous reports of prolonged cVEP latency suggest a vehicle for detecting abnormal ganglion cells and for monitoring neuroprotection. METHODS: Seventy-five glaucomatous eyes (47 patients), 75 eyes with suspected glaucoma (46 patients), and 41 control eyes (22 subjects) underwent achromatic automated perimetry and mfVEP and cVEP testing. The mfVEP stimulus was a scaled dart board with 60 sectors; each sector was a pattern-reversing checkerboard. The cVEP stimulus was a reversing checkerboard with checks of either 15 minutes or 60 minutes in width. RESULTS: Relatively few glaucomatous eyes had latencies that fell outside the range of control eyes, and there was little difference between the cVEP and mfVEP results. In the glaucoma group, 12.3% (15 minutes cVEP), 8% (60 minutes cVEP), and 17.3% (mfVEP) of the eyes and 5.3% (15 minutes cVEP), 6.7% (60 minutes cVEP), and 5.3% (mfVEP) of the suspect eyes exceeded the normal range. The glaucomatous eyes had, on average, relatively small increases in latency, compared with the control or suspect groups. Further, the latency of both the mfVEP and cVEP bore no obvious relationship to the mean deviation of the visual field. CONCLUSIONS: Contrary to previous reports, prolonged VEP delays were present in a minority of patients with glaucoma. Either a delayed VEP is not a good indicator of damaged, as opposed to dead, retinal ganglion cells, or there are relatively few patients who exhibit evidence of damaged ganglion cells