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Biomedical subjects

Donald C Hood

Publications and source records attributed to Donald C Hood.

At least 19 recordsLinked to original sources
PubMed2006

Multifocal visual-evoked potential in unilateral compressive optic neuropathy.

AIM: To evaluate the effects of unilateral compressive optic neuropathy on amplitude and latency of multifocal visual evoked potentials (mfVEPs). METHODS: Static automated perimetry and mfVEP recordings were obtained from six patients with presumed meningiomas affecting one optic nerve. Monocular and interocular amplitude and latency analyses were performed and compared with normal control subjects. RESULTS: The change in the mfVEP amplitude agreed with visual field findings with regard to topography and severity of deviation from normal. The delay in recordable responses from affected eyes ranged from 7.6 to 20.7 ms (interocular analysis) and 7.9 to 13.9 ms (monocular analysis). CONCLUSIONS: Compressive optic neuropathy decreases the amplitude and increases the latency of the mfVEP. The changes in latency were similar to those seen in optic neuritis but larger than those in ischaemic optic neuropathy and glaucoma.

Aged↗
PubMed2006

Contrast-response functions for multifocal visual evoked potentials: a test of a model relating V1 activity to multifocal visual evoked potentials activity.

The multifocal visual evoked potential (mfVEP) is largely generated in V1. To relate the electrical activity recorded from humans to recordings from single cells in nonhuman primate (V1) cortex, contrast-response functions for the human mfVEP were compared to predictions from a model of V1 activity (D. J. Heeger, A. C. Huk, W. S. Geisler, & D. G. Albrecht, 2000) based upon single-cell recordings from monkey V1 (e.g., D. G. Albrecht, 1995; D. G. Albrecht, W. S. Geisler, R. A. Frazor, & A. M. Crane, 2002; D. G. Albrecht & D. B. Hamilton, 1982; W. S. Geisler & D. G. Albrecht, 1997). A second purpose was to fully articulate the assumptions of this model to better understand the implications of this comparison. Finally, as the third purpose, one of these assumptions was tested. Monocular mfVEPs were obtained from normal subjects with a contrast-reversing dartboard pattern. The display contained 16 sectors each with a checkerboard. Both the sectors and the checks were scaled approximately for cortical magnification. In Experiment 1, there were 64 checks per sector. The contrast-response functions were fitted well up to 40% contrast by the theoretical population curve for V1 neurons; there was a systematic deviation for higher contrasts. The model, as articulated here, predicts that the contrast-response function should be the same and independent of the size of the elements in the display. Varying the size of the elements by varying the viewing distance in Experiment 2 produced similar results to those in Experiment 1. In Experiment 3, the viewing distance and sector size were held constant, but the size of the elements (and therefore the number of checks per sector) was varied. Changing check size by a factor of 16 had relatively little effect on the contrast-response function. In general, the mfVEP results were consistent with the model based upon the V1 neuron population. However, two aspects of the results require further exploration. First, there was a systematic deviation from the model's contrast-response function for higher contrasts. This deviation suggests that one or more of the model's assumptions may be violated. Second, the latency of the mfVEP changed far less than expected based upon single-cell data.

Adult↗
PubMed2006

Repeatability of normal multifocal VEP: implications for detecting progression.

PURPOSE: To assess the repeatability of the multifocal visual evoked potential (mfVEP) and to compare it with the repeatability of standard automated perimetry (SAP) in the same group of 50 normal controls retested after 1 year. Our second aim was to assess the repeatability of false alarm rates determined previously for the mfVEP using various cluster criteria. METHODS: Fifty individuals with normal vision participated in this study (33 females and 17 males). The age range was 26.7 to 77.9 years and the group average age (+/- SD) was 51.4 (+/- 12.1) years. Pattern-reversal mfVEPs were obtained using a dartboard stimulus pattern in VERIS and two 8-minute runs per eye were averaged. The average number of days between the first and second mfVEP tests was 378 (+/- 58). SAP visual fields were obtained within 17.4 (+/- 20.3) days of the mfVEP using the SITA-standard threshold algorithm. Repeatability of mfVEPs and SAP total deviation values were evaluated by calculating point-wise limits of agreement (LOA). Specificity (1-false alarm rate) was evaluated for a range of cluster criteria, whereby the number and probability level of the points defining a cluster were varied. RESULTS: Point-wise LOA for the mfVEP signal-to-noise ratio (SNR) ranged from 2.0 to 4.3 dB, with an average of 2.9 dB across all 60 locations. For SAP, LOA ranged from 2.4 to 8.9 dB, with an average of 4.0 dB (excluding the points immediately above and below the blind spot). Clusters of abnormal points were not likely to repeat on either mfVEP or SAP. When an mfVEP abnormality was defined as the repeat presence (confirmation) of a 3-point (P < 0.05) cluster anywhere within a single hemifield, only 1 (of 200) monocular hemifield was deemed abnormal. Although the LOA of the mfVEP were similar throughout the field, the limited dynamic range of SNR at superior field locations will limit the ability to follow progression in "depth" at those locations. CONCLUSIONS: Repeatability of the mfVEP was slightly better than SAP visual fields in this group of controls with a 1-year retest interval. This suggests that progression in early stages should be more easily detectable by mfVEP. However, in certain field locations (eg, superior periphery), the relatively more narrow dynamic range of the SNR of the mfVEP may limit detection of progression to just 1 event. Confirmation of a 3-point cluster abnormality is highly suggestive of a true defect on the mfVEP.

Adult↗
PubMed2006

Detecting early functional damage in glaucoma suspect and ocular hypertensive patients with the multifocal VEP technique.

PURPOSE: To determine whether the multifocal visual evoked potential (mfVEP) technique can detect early functional damage in ocular hypertensive (OHT) and glaucoma suspect (GS) patients with normal standard achromatic automated perimetry (SAP) results. PATIENTS AND METHODS: Twenty-five GS patients (25 eyes), 25 patients with OHT (25 eyes), and 50 normal controls (50 eyes) were enrolled in this study. All GS, OHT and normal control eyes had normal SAP as defined by a pattern standard deviation and mean deviation within the 95% confidence interval and a glaucoma hemifield test within normal limits on the Humphrey visual field 24-2 program. Eyes with GS had optic disc changes consistent with glaucoma with or without raised intraocular pressure (IOP), and eyes with OHT showed no evidence of glaucomatous optic neuropathy and IOPs >or=22 mm Hg. Monocular mfVEPs were obtained from both eyes of each subject using a pattern-reversal dartboard array with 60 sectors. The entire display had a radius of 22.3 degrees. The mfVEPs, for each eye, were defined as abnormal when either the monocular or interocular probability plot had a cluster of 3 or more contiguous points with P<0.05 and at least 2 of these points with P<0.01. RESULTS: The mfVEP results were abnormal in 4% of the eyes from normal subjects. Abnormal mfVEPs were detected in 20% of the eyes of GS patients and 16% of the eyes of OHT patients. Significantly more mfVEP abnormalities were detected in GS patients than in normal controls. However, there was no significant difference in mfVEP results between OHT patients and normal controls. CONCLUSIONS: The mfVEP technique can detect visual field deficits in a minority of eyes with glaucomatous optic disks and normal SAP results.

Disease Progression↗
PubMed2006

The effects of retinal abnormalities on the multifocal visual evoked potential.

PURPOSE: To examine the effects on the amplitude and latency of the multifocal visual evoked potential (mfVEP) in retinal diseases associated with depressed multifocal electroretinograms (mfERG). METHODS: Static automated perimetry (SAP), mfERGs, and mfVEPs were obtained from 15 individuals seen by neuro-ophthalmologists and diagnosed with retinal disease based on funduscopic examination, visual field, and mfERG. Optic neuropathy was ruled out in all cases. Diagnoses included autoimmune retinopathy (n = 3), branch retinal arterial occlusion (n = 3), branch retinal vein occlusion (n = 1), vitamin A deficiency (n = 1), digoxin/age-related macular degeneration (n = 1), multiple evanescent white dot syndrome (n = 1), and nonspecific retinal disease (n = 5). Patients were selected from a larger group based on abnormal mfERG amplitudes covering a diameter of 20 degrees or greater. RESULTS: Fourteen (93%) of 15 patients showed significant mfVEP delays, as determined by either mean latency or the probability of a cluster of delayed local responses. Thirteen of 15 patients had normal mfVEP amplitudes in regions corresponding to markedly reduced or nonrecordable mfERG responses. These findings can be mimicked in normal individuals by viewing the display through a neutral-density filter. CONCLUSIONS: Retinal diseases can result in mfVEPs of relatively normal amplitudes, often with delays, in regions showing decreased mfERG responses and visual field sensitivity loss. Consequently, a retinal problem can be missed, or dismissed as functional, if a diagnosis is based on an mfVEP of normal or near-normal amplitude. Further, in patients with marked mfVEP delays, a retinal problem could be confused with optic neuritis, especially in a patient with a normal appearing fundus.

Adult↗
PubMed2006

A comparison between multifocal and conventional VEP latency changes secondary to glaucomatous damage.

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.

Adolescent↗
PubMed2005

The pattern electroretinogram in glaucoma patients with confirmed visual field deficits.

PURPOSE: To better understand the relationship between the amplitude of the pattern electroretinogram (PERG) and visual loss, measured with static automated perimetry. METHODS: Transient PERGs were recorded in 15 patients (31-77 years) and 16 normal individuals (26-65 years). An eye was considered to have glaucomatous damage only if there was an abnormal disc, an abnormal 24-2 Humphrey visual field result (pattern stand deviation, glaucoma hemifield test, and cluster) and an abnormal multifocal visual evoked potential. All the worse (more affected) eyes of the patients and six of the better eyes met these criteria. The N95 amplitude of the PERG was measured from the positive peak (P50) at approximately 50 ms to the trough at approximately 95 ms. The ratio of N95 to P50-the N95 amplitude divided by the P50 amplitude-was also measured. RESULTS: First, the PERG was within normal limits for 4 (26.7%) of the worse eyes. Overall, 6 (28.6%) of the 21 eyes that met the criteria for glaucomatous damage had normal PERGs on both PERG measures. Because the normal individuals were younger than the patients, an even larger number of normal PERGs might be expected with an age-appropriate control group. Second, the N95 amplitude was nonlinearly related to visual field sensitivity when sensitivity was plotted on a linear plot. Small field losses were associated with disproportionately large losses in PERG amplitude. Third, the PERG from both eyes of a patient were very similar, even when the visual fields suggested very different levels of damage. CONCLUSIONS: These results are consistent with the view that very early damage can affect the PERG, even before the visual field shows a loss. At the same time, it is clear that patients with clear glaucomatous damage can have normal-appearing PERGs. An explanation is proposed to account for these findings.

Adult↗
PubMed2004

The multifocal visual evoked potential: an objective measure of visual fields?

We examined the effects of inter-modal attention and mental arithmetic on Humphrey visual field sensitivity and multifocal visual evoked potential (mfVEP) amplitude. Four normally sighted subjects (ages ranging from 24 to 58 years) participated in this study. Monocular visual field sensitivity was measured under two conditions: (1) standard testing condition and (2) while the subject performed a Paced Auditory Serial Addition Task (PASAT). Monocular mfVEPs were recorded in response to a 60-sector stimulus. The checkerboard pattern in each sector was contrast reversed according to a binary m-sequence. mfVEPs were recorded under two conditions: (1) standard testing conditions and (2) while the subject performed a PASAT. We found that, when compared to the no-task condition, all subjects had locations of significantly reduced Humphrey visual field sensitivities when performing the PASAT. In contrast, there were no significant decreases in mfVEP amplitude in any sector for any of the subjects while performing the PASAT. Our findings indicate that divided attention and ongoing mental processes did not affect the mfVEP. Therefore, the mfVEP provides an objective measure of visual field function that may be useful for some patients with unreliable automated static perimetry results.

Adult↗
PubMed2004

A principal component analysis of multifocal pattern reversal VEP.

Multifocal visual evoked potentials (mfVEP) were recorded with three channels from 31 control subjects. A principal component analysis was applied to all local responses. The first principal component reversed polarity above and below the horizontal meridian in the case of the midline channel and across the vertical meridian in the case of the lateral channel. In addition, the first principal components of the responses around the vertical meridian were reversed in polarity compared to those around the horizontal meridian, consistent with the region near the vertical meridian lying outside the calcarine fissure. A model was proposed that allowed for the construction of a coronal section of V1 based on the distribution of the first principal component. This approach provides a means of deriving a V1 component from mfVEP recordings with only three recording channels.

Adult↗
PubMed2004

A method for comparing electrophysiological, psychophysical, and structural measures of glaucomatous damage.

OBJECTIVE: To develop a method for comparing multifocal visual-evoked potential (mfVEP) responses and behaviorally determined visual fields with structural measures of the optic nerve head. METHODS: Humphrey 24-2 visual fields and mfVEPs were obtained from each eye of 20 patients with open-angle glaucoma. Monocular and interocular analyses were performed to identify locations with abnormal mfVEP responses. Optic discs were assessed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph II). The image of the optic nerve head was divided into 6 sectors. The rim and disc area measurements for each sector were compared with those in a normal database using Moorfields regression analysis. The optic nerve head measurements for the 6 sectors were related to the Humphrey visual field locations and the 60 sectors of the mfVEP display. RESULTS: Of 240 sectors tested (40 eyes x 6 sectors), 18.8% on Humphrey visual field, 22.1% on mfVEP, and 10.8% on confocal scanning laser ophthalmoscopic testing were significantly different from those of control subjects. There were no significant deficits in 165 sectors. There was agreement for 86.7% of the sectors when the Humphrey visual field and mfVEP results were compared. The confocal scanning laser ophthalmoscopic results were in agreement for 84.6% of these sectors. CONCLUSIONS: The method used allows for a comparison among measures of visual function and a structural measure of the optic nerve head. In general, the results of the functional and structural measures showed agreement; however, there were clear examples of disagreements that merit further study.

Adult↗
PubMed2004

Normative ranges and specificity of the multifocal VEP.

PURPOSE: To describe a normative database for the multifocal VEP (mfVEP) and to evaluate specificity for a range of cluster criteria. METHODS: One hundred persons (62 females and 38 males) with normal visual fields and ranging in age from 21.6 to 92.4 years participated in this study. Self-reported race in 80 of these 100 persons was 'White or Caucasian,' eight were 'Black or African-American,' eight were 'Asian,' and four were 'Hispanic or Latino.' Pattern-reversal mfVEPs were obtained using a dartboard stimulus pattern in VERIS and two 8-min runs per eye were averaged. A bootstrap technique was used to estimate the normal range of mfVEP response signal-to-noise ratio (SNR) and inter-ocular amplitude ratio at each location. Specificity (1 - false alarm rate) was evaluated for a range of cluster criteria, whereby the number and probability level of the points defining a cluster were varied. RESULTS: There was no overall effect of age on SNR (r2 = 0.16, p = 0.22) nor was the interaction between age and location significant (F = 0.83, p = 0.82, ANOVA). The location with the largest age effect had an r2 of only 0.13. There was a small but significant effect of sex (t = 2.1, p = 0.04) such that SNR was slightly (11%) larger in females than males, but there was no significant interaction between sex and age (t = 0.82, p = 0.41). There was a slight trend toward higher SNR in the Asian group and lower SNR in the African-American group, but the overall effect of race was not significant (F = 1.99, p = 0.12). Specificity depended on the number and probability level of the points defining a cluster. Specificity did not vary by age group in a simple monotonic manner. False positive rates were slightly higher in females than males, and slightly higher in the African-American group as compared with the Asian group. CONCLUSIONS: Excellent specificity can be achieved for the mfVEP by using particular cluster criteria for monocular and inter-ocular tests. The effects of age, sex, and race were all very small and only the effect of sex was statistically significant. This normative database can be used for analyses of mfVEP results from individual patients with little risk that demographic factors such as age and sex will confound diagnostic accuracy.

Adult↗
PubMed2004

Increasing the sensitivity of the multifocal visual evoked potential (mfVEP) technique: incorporating information from higher order kernels using a principal component analysis method.

Principal component analysis (PCA) was employed to enhance the multifocal visual evoked potential (mfVEP) technique. First, by using four principal components, the separation of mfVEP signals from noises was improved. Second, two otherwise unused higher order kernels, the 2nd slice of the 2nd order kernel and the 4th order kernels, were utilized by combining information obtained from the PCA. The PCA-kernel method improves the efficiency of the mfVEP test. The false positive rate, based upon an analysis of a noise window, was decreased by a factor of about one-third and the improvement in sensitivity of detecting glaucomatous defects was nearly as good as a doubling of the recording time.

Diagnostic Techniques, Ophthalmological↗
PubMed2004

Determining abnormal interocular latencies of multifocal visual evoked potentials.

PURPOSE: To describe methods for measuring interocular latency differences of multifocal visual evoked potentials (mfVEP) and for determining regions with abnormal interocular latencies in patients. METHODS: The mfVEPs from 100 individuals with normal visual fields and normal fundus examinations were analyzed. Individuals ranged in age from 21.6 to 92.4 years. The stimulus was a 60 sector, pattern-reversing dartboard display. Each sector had 16 checks, 8 white (200 cd/m2) and 8 black (< 1 cd/m2). Interocular latency was measured as the temporal shift producing the best cross-correlation value between the corresponding responses of each eye. The 'corrected interocular latency' was defined as the difference between this shift and the mean interocular latency (shift) for a particular sector and recording channel. RESULTS: The variability of the corrected interocular latency decreased as the signal-to-noise ratio (SNR) of the mfVEP responses increased. For example, the 95% confidence intervals decreased from over 16 ms to under 4 ms as SNR increased. Grouping and summing the responses also lead to an increase in SNR and a decrease in the confidence interval. The results of various cluster criteria were also derived. A cluster criterion (e.g. two or more contiguous points within a hemisphere exceeding a given confidence interval), can serve to increase the specificity for detection of eyes or individuals with abnormal interocular latencies. For example, while 21% of the eyes had 3 or more points exceeding the 5% confidence interval, only 1.8% of the eyes had a cluster of 3 or more of these points. Finally, interocular latency was only weakly correlated with age (r = 0.26). CONCLUSION: In testing for abnormalities in interocular latencies, the confidence interval should be based upon the SNR of the response. Grouping and summing responses to increase SNR or employing a cluster test may also prove useful.

Acute Disease↗
PubMed2004

Determining abnormal latencies of multifocal visual evoked potentials: a monocular analysis.

PURPOSE: To describe a methodology for measuring abnormal timing of monocular multifocal visual evoked potentials (mfVEP). METHODS: The mfVEPs from 100 individuals with normal visual fields and normal fundus exams were analyzed. The stimulus was a 60 sector, pattern-reversing dartboard display. For each of the 60 locations of the dartboard and each channel and each eye, a template was derived based upon the average of the responses from the 100 normal individuals. In deriving this template, care was taken to exclude those responses reversed in polarity as compared to the average response. The best array of responses for each individual was compared to these templates. The relative latency of each response was measured as the temporal shift producing the best cross-correlation value. RESULTS: The 95% confidence interval (CI) decreased as the signal-to-noise ratio (SNR) of the mfVEP responses increased. For example, the 95% CI decreased from over 17 ms to under 9 ms as the SNR increased. Grouping and summing the responses also lead to an increase in SNR and a decrease in CI. Because the number of points exceeding the CI is not randomly distributed among normal individuals, a cluster criterion (e.g. two or more contiguous points within a hemisphere exceeding a given confidence interval) can be helpful. For example, while 18% of the eyes had 5 or more points exceeding the 5% confidence interval, only 6.5% of the eyes had a cluster of 5 of these points. The correlation between relative latency and age was relatively low (r = 0.46). CONCLUSION: For detecting abnormalities in the timing of monocular, mfVEP responses, a template method provides a reasonable approach. In devising a particular test for abnormal timing, the CI should be based upon the SNR of the response. In addition, grouping and summing responses to increase SNR or employing a cluster test may also prove useful.

Acute Disease↗
PubMed2004

Auto-immune-like cone dystrophy.

PURPOSE: To describe rapid loss of cone vision in an adult due to putative auto-immune rejection. METHODS: Clinical and electrophysiological examination, including full-field and multi-focal electroretinograms (ERGs), were used to assess retinal function. Serum was analyzed for antibodies to retinal antigens. RESULTS: The patient lost cone vision in the course of several months while rod vision remained unaffected. Initially short wavelength (S) cone function appeared more resistant to the degeneration. Cancer associated retinal antibodies were present in the sera of the patient but no cancer has been found. CONCLUSION: Rapid loss of cone function can occur in an adult without a concomitant neoplasm although serum antibodies to retinal antigens suggest an autoimmune cause.

Aged↗
PubMed2004

Electrophysiologic imaging of retinal and optic nerve damage: the multifocal technique.

Multifocal VEP technology is still in its infancy. Although many aspects of the recording and analysis will be improved with time, the mfVEP can be used in the clinic today. It can help to identify functional (nonorganic) problems, demyelinating diseases, glaucomatous damage, and poor field takers. Given the software and techniques needed to record and interpret the results, mfVEP testing should be performed in centers experienced with this technique.

Diagnosis, Differential↗
PubMed2004

Detecting early to mild glaucomatous damage: a comparison of the multifocal VEP and automated perimetry.

PURPOSE: To gain better understanding of the relationship between abnormalities detected by the multifocal VEP (mfVEP) compared with those detected by static achromatic, automated perimetry in patients with glaucoma. METHODS: Fifty patients were studied who had open-angle glaucoma that met the following criteria: (1) a mean deviation (MD) of better than -8 dB in both eyes on the 24-2 Humphrey visual field (HVF) test (Carl Zeiss Meditec, Dublin, CA); and (2) glaucomatous damage in at least one eye, as defined by a glaucomatous optic disc and an abnormal 24-2 HVF test result (pattern standard deviation [PSD] <5% and/or glaucoma hemifield test [GHT] results outside normal limits). Monocular mfVEPs were obtained from each eye by using a pattern-reversal dartboard array, 44.5 degrees in diameter, which contained 60 sectors. Recording electrodes were placed at the inion (I) and I+4 cm, and also at two lateral locations up 1 cm and over 4 cm from I. Monocular and interocular mfVEP probability plots were derived by comparing the results with those of normal control subjects. For both the HVF and mfVEP probability plots, a hemifield was classified as abnormal if three or more contiguous points were significant at less than 5%, with at least one at less than 1%. RESULTS: Of the 200 hemifields tested (50 patients x two eyes x two hemifields), 75 showed significant clusters on the HVF, and 74 (monocular probability plot) and 93 (monocular or interocular plot) showed significant clusters on the mfVEP. Overall, the HVF and mfVEP results agreed on 74% of the hemifields, and 90 hemifields were normal and 58 were abnormal on both the mfVEP (interocular and/or monocular abnormal) and HVF cluster tests. Of the 52 disagreements, 35 hemifields had a significant cluster on the mfVEP, but not on the HVF, whereas the reverse was true of 17 hemifields. A case-by-case analysis indicated that misses and false-positive results occurred on both the HVF and mfVEP tests. CONCLUSIONS: As predicted from a theoretical analysis, under these conditions (i.e., the signal-to-noise level) the HVF and monocular mfVEP tests showed a comparable number of defects, and, with the addition of the interocular test, the mfVEP showed more abnormalities than the HVF. However, although there were abnormalities detected by the mfVEP that were missed by the HVF, the reverse was true as well.

Adult↗