Flimmerprovokation im LED-Ganzfeld bei Gesunden und Glaukompatienten

BACKGROUND: Flicker light is an easy method to test sensory function after stress. The aim of this study was to determine the influence of flicker stress on temporal contrast sensitivity in healthy controls and patients with glaucomatous alteration of the optic disk. METHODS: A commercially available full-field stimulator (Retiport, Roland Consult) equipped with white LEDs was modified to perform psychophysical tests. The patients underwent measurements of the recovery time interval from cessation of flicker stress until recognition of a pregiven flicker contrast after photo stress. In addition, we studied contrast sensitivity with a continuous flickering target and with a flicker burst protocol avoiding adaptation to prevailing flicker. All tests were performed at a constant retinal illumination and at a frequency of 37 Hz for provocation as well as for contrast sensitivity tests. SUBJECTS: Normal healthy controls (40), "preperimetric" (62), and "perimetric" (52) open-angle glaucoma patients were studied. Exclusion criteria were age lower than 31 years, visual acuity under 0.6, and perimetric mean defect more than 9.5 dB. RESULTS: Recovery time after flicker stress was significantly longer in patients than in normals and longer in perimetric than in preperimetric patients. Analysis in perimetric patients revealed a larger area under ROC for the provocation test (0.95) than in contrast sensitivity tests (continuous flicker method: 0.90, flicker burst mode: 0.84). CONCLUSION: High-power LEDs which are installed in modern full-field devices can be used as a helpful tool to study psychophysical properties. In the present study it could be shown that threshold, adaptation, and recovery of temporal transfer characteristics are impaired in many patients with glaucoma.     

Linearity can account for the similarity among conventional, frequency-doubling, and gabor-based perimetric tests in the glaucomatous macula.

PURPOSES: The purposes of this study are to compare macular perimetric sensitivities for conventional size III, frequency-doubling, and Gabor stimuli in terms of Weber contrast and to provide a theoretical interpretation of the results. METHODS: Twenty-two patients with glaucoma performed four perimetric tests: a conventional Swedish Interactive Threshold Algorithm (SITA) 10-2 test with Goldmann size III stimuli, two frequency-doubling tests (FDT 10-2, FDT Macula) with counterphase-modulated grating stimuli, and a laboratory-designed test with Gabor stimuli. Perimetric sensitivities were converted to the reciprocal of Weber contrast and sensitivities from different tests were compared using the Bland-Altman method. Effects of ganglion cell loss on perimetric sensitivities were then simulated with a two-stage neural model. RESULTS: The average perimetric loss was similar for all stimuli until advanced stages of ganglion cell loss, in which perimetric loss tended to be greater for size III stimuli than for frequency-doubling and Gabor stimuli. Comparison of the experimental data and model simulation suggests that, in the macula, linear relations between ganglion cell loss and perimetric sensitivity loss hold for all three stimuli. CONCLUSIONS: Linear relations between perimetric loss and ganglion cell loss for all three stimuli can account for the similarity in perimetric loss until advanced stages. The results do not support the hypothesis that redundancy for frequency-doubling stimuli is lower than redundancy for size III stimuli.     

High-frequency flicker visual-evoked potential losses in glaucoma

Anatomic evidence indicates that glaucoma initially destroys large axons before affecting smaller ones. Large axonal size has been correlated with fast, transiently responding retinal ganglion cells (alpha/Y cells). A second population of cells (X cells) does not follow flicker stimulation to as high a frequency as Y cells. The luminance flicker visual-evoked potential (VEP) shows two response maxima as a function of temporal frequency. These two response peaks may indicate driving of the flicker VEP by two separate neuronal populations, possibly X and Y cells. The authors have recorded flicker VEPs as a function of frequency from both normal subjects and glaucoma patients with asymmetric visual field loss in various stages of their disease. The data obtained demonstrate loss of high flicker rate responses apparently preceding and correlated with perimetric field loss and stage of glaucoma. Flicker VEP responses below 13 Hz tend to be preserved, whereas above this frequency the response attenuation is directly proportional to the severity of visual loss. This technique may provide an early warning of ganglion cell loss in the early stages of this disease.     

Flicker-evoked response measured at the optic disc rim is reduced in ocular hypertension and early glaucoma

PURPOSE: To determine in patients with ocular hypertension (OHT) or early glaucoma (EOAG) the change in blood flow measured at the neuroretinal rim of the optic disc in response to a 15-Hz diffuse green luminance flicker, a stimulus that activates predominantly the ganglion cell magnocellular pathway. METHODS: Thirteen patients with EOAG, 29 with OHT, and 16 age-matched control subjects, all with excellent fixation, were examined. Blood flow (F(onh)) at the neuroretinal rim of the optic disc was continuously monitored by laser Doppler flowmetry before and during exposure to a 15-Hz, 30 degrees field green luminance flicker. The response of F(onh) to this stimulus (RF(onh)) was expressed as percentage change in F(onh) between baseline and the last 20 seconds of flicker. Two to three temporal sites of the disc were tested, and the highest RF(onh) was considered for further analysis. RF(onh) results in patients were correlated with morphologic (cup-to-disc area ratio, cup shape neuroretinal rim area) and functional (perimetric mean deviation and pattern electroretinogram amplitude) clinical parameters. RESULTS: In the patients with OHT or EOAG, F(onh) and RF(onh) were both reduced compared with their respective values in the control group. Both quantities decreased significantly with neuroretinal rim area when the patients' data were pooled. No significant correlation was found between F(onh) or RF(onh) and the other morphometric and functional parameters. The group-averaged time course of RF(onh) was not significantly different from that in the normal subjects. CONCLUSIONS: Luminance flicker-evoked RF(onh) is abnormally reduced in patients with OHT or EOAG, indicating an impairment of neurally mediated vasoactivity. The data suggest that PERG-derived neural activity and flicker-evoked RF(onh) can be independently altered early in the disease process.     

Perimetric defects and ganglion cell damage: interpreting linear relations using a two-stage neural model

PURPOSE: To better understand the relations between glaucomatous perimetric defects and ganglion cell damage, a neural model was developed to interpret empiric findings on linear relations between perimetric defects and measures of ganglion cell loss. METHODS: A two-stage model computed responses of ganglion cell mosaics (first stage), then computed perimetric sensitivity in terms of processing by spatial filters (second stage) that pool the ganglion cell responses. Cell death and dysfunction were introduced in a local patch of the first-stage ganglion cell mosaic, and perimetric defect depth was computed for the corresponding region of the visual field. Calculations were performed for both sparse and dense ganglion cell mosaics and for spatial filters with peak frequencies from 0.5 to 4.0 cyc/deg. RESULTS: The model yielded nonlinear functions for perimetric defect depth in decibel versus the percentage of ganglion cell damage, but functions for lower spatial frequencies became linear when perimetric defect was expressed as a percentage of normal. The relations between perimetric defects and percentage of ganglion cell loss were determined primarily by spatial tuning of the second-stage spatial filters. For averaging sensitivities across different visual field locations, linear units (arithmetic mean) can more closely approximate mean ganglion cell loss than decibel units (geometric mean). Fits to data from experimental glaucoma required ganglion cell dysfunction in addition to ganglion cell loss. CONCLUSIONS: Pooling by second-stage spatial filters can account for empiric findings of linear relations between perimetric defects and measures of ganglion cell loss.     

Posterior pole retinal thickness in ocular hypertension and glaucoma: early changes detected by hemispheric asymmetries

PURPOSE: To evaluate retinal thickness at the posterior pole of the fundus in ocular hypertension (OHT) and open-angle glaucoma (OAG), and to correlate morphometric findings with visual sensitivity as determined by automated perimetry. METHODS: One randomly selected eye from 41 patients with clinical diagnosis of OHT (n = 25) or early to moderate OAG (n = 16) and 16 age-matched normal controls was examined. Retinal thickness was measured by Retinal Thickness Analyzer (RTA), acquiring 5 pre-defined scans covering the central 20 degrees of the fundus. RTA average thickness and thickness profile data, including hemispheric asymmetries calculated as relative (superior/inferior and nasal/temporal) or absolute (vertical and horizontal, ie, independent of which hemisphere was thinner) parameters, were calculated. For each eye, white-on-white Humphrey 30-2 visual field results were analyzed, in addition to standard global indices, by quantifying perimetric sensitivities for regions of the posterior pole corresponding to those sampled by the RTA. RESULTS: On average, central retinal thickness was reduced (P < 0.05) in OAG compared with OHT or normal control eyes. Vertical hemispheric absolute thickness asymmetry was increased (P < or = 0.01) in OAG eyes compared with the other groups. Horizontal hemispheric absolute thickness asymmetry was increased (P < 0.01) in both OHT and OAG eyes, compared with control eyes. At least one of the RTA parameters was altered in 13 of 25 OHT (52%) and 12 of 16 OAG eyes (75%), most frequently involving thickness asymmetries. In OAG, but not OHT eyes, superior/inferior asymmetry was positively (r = 0.69, P < 0.01) correlated with the corresponding asymmetry in perimetric sensitivity. CONCLUSIONS: The RTA can reveal increased hemispheric thickness asymmetries in both OHT and OAG eyes. In OAG eyes thickness asymmetries are associated with corresponding perimetric asymmetries. The findings in OHT eyes suggest that localized anatomic and functional damage to inner retina may not develop in parallel early in the disease process.     

Frequency doubling technology perimetry with the Humphrey Matrix 30-2 test

PURPOSE: To assess the Humphrey Matrix 30-2 test in detecting functional glaucomatous damage. PATIENTS AND METHODS: One eye in each of 60 healthy individuals, 108 patients with ocular hypertension (OHT), and 150 patients with preperimetric (48) or perimetric (102) high-tension primary open-angle glaucoma (POAG) were considered. Visual fields were assessed by the standard automated perimetry (SAP) Humphrey Field Analyzer 30-2, frequency doubling technology (FDT) N-30, and Humphrey Matrix 30-2 tests. Significantly abnormal points in the pattern deviation probability plot, testing time, sensitivity, specificity, and area under the receiver operating characteristic curve of the FDT tests were evaluated. RESULTS: FDT revealed a significantly greater percentage of depressed points than did SAP in OHT and preperimetric POAG eyes. The FDT-N-30 test showed a significantly greater percentage of areas with P < 5% in the OHT, preperimetric POAG, and early POAG groups. The Matrix-30-2 test provided an area under the receiver operating characteristic curve slightly lower than the FDT-N-30 test in the preperimetric POAG group, and significantly greater in the perimetric POAG group. CONCLUSIONS: FDT perimetry appeared more sensitive than SAP in detecting early glaucomatous VF loss. The FDT-N-30 test showed a slightly higher ability to detect early glaucomatous damage in patients at risk for the development of glaucoma, whereas the Matrix-30-2 test provided a more detailed characterization of the glaucomatous VF loss pattern, although it required 30% more time.     

Psychophysical investigation of ganglion cell loss in early glaucoma

PURPOSE: To evaluate ganglion cell loss in early glaucoma using a variety of psychophysical tests and to identify optimal perimetric technique(s) for detection of early glaucomatous visual function loss. METHODS: Five perimetric tests, short wavelength automated perimetry (SWAP), temporal modulation perimetry (TMP), frequency doubling technology perimetry (FDT), detection acuity perimetry (DAP), and resolution acuity perimetry (RAP) were compared in their ability to discriminate between normal individuals and patients with early glaucoma or glaucoma suspects. Comparisons were also made by their ability to produce repeatable defects. The tests examined different visual functions that are likely to be mediated by different retinal ganglion cell subpopulations, thereby permitting examination of hypotheses of ganglion cell death in early glaucoma. RESULTS: All visual field tests demonstrated high performance in separating glaucoma patients from normal individuals. SWAP, TMP, FDT, and DAP provided the greatest discrimination between normal individuals and high- and low-risk glaucoma suspects. However, SWAP, TMP, and FDT obtained better consistency across the various analysis approaches (global indices and pointwise) than DAP and RAP. Of all the test types, FDT exhibited the highest proportion of repeatable abnormal test locations, with poor confirmation rates achieved by DAP and RAP. CONCLUSION: The performance of SWAP, FDT, and TMP suggests that these test types may all be suitable for detection of early loss of visual function in glaucoma. Ganglion cell subpopulations with lower levels of redundancy and/or those with larger cell sizes offer the most parsimonious explanation for earliest ganglion cell losses occurring in glaucoma.     

Structure–function relationship in ocular hypertension and glaucoma: interindividual and interocular analysis by OCT and pattern ERG

BACKGROUND: Pattern electroretinogram (PERG) and optical coherence tomography (OCT) represent objective probes to investigate respectively the function of retinal ganglion cells and their structure as retinal nerve fiber layer (RNFL) thickness. We examined interindividual (II) correlations of PERG amplitude and RNFL thickness, as well as correlations between interocular (IO) differences in both measures, in ocular hypertension (OHT) and early glaucoma (EG) patients. METHODS: Thirty-one OHT, 34 EG (mean deviation: -1 to -6 dB) and 16 age-matched controls were examined in both eyes. Participants had clear optical media, no or moderate refractive errors and no concomitant ocular or systemic diseases. PERGs were elicited by counterphased (16.28 reversals/second) gratings (1.6 cycles/degree spatial frequency). The Fourier isolated 2nd harmonic PERG amplitude and phase were measured. RNFL thickness was quantified by means of OCT Stratus according to a standard protocol. Average, superior and inferior RNFL thicknesses were considered. RESULTS: Mean PERG amplitude was decreased (p < 0.01) in both OHT and EG patients compared to controls. Mean RNFL thicknesses were reduced (p < 0.01) in EG patients compared to both OHT and controls. In OHT patients, PERG amplitude did not correlate significantly with RNFL thickness in both II and IO analysis. In EG patients, PERG amplitude was positively correlated with RNFL thickness in both II (p < 0.005) and IO (p < 0.001) analysis. The slope of the correlation predicted that PERG losses exceeded systematically RNFL losses when the latter were between 0 and -0.25 log units. CONCLUSIONS: Both II and IO analyses revealed a lack of structure-function relationship in OHT, suggesting that, at this disease stage, PERG losses appear to affect primarily retinal/optic nerve head function. In EG they reflect both dysfunction and RNFL loss.     

Foveal and non-foveal measures of short wavelength sensitive pathways in glaucoma and ocular hypertension

Blue-sensitive cone thresholds (the ability to detect blue test lights presented on a bright yellow background) were measured to examine foveal and central vision field sensitivity in groups of 33 glaucoma, 31 ocular hypertension (OHT) and 24 age matched normal subjects. Results showed these thresholds were substantially reduced (in all areas tested) for the glaucoma group (approximately 0.8 log units) and less reduced for the OHT group (approximately 0.2 log units), when compared to the normal group threshold. Measures of red-sensitive and green-sensitive cone thresholds showed no difference for all three groups. Furthermore, 16% of the OHT group showed visual field abnormalities for the blue-sensitive cone threshold measure. We conclude that efforts to detect early function loss in glaucoma and OHT could be improved using these measures in clinical practice.     

Light perception and flicker perimetry. Effect of refractive error, artificial media opacities and pupillary size]

The influence of defocus, artificial media opacities and pupil size on perimetric thresholds in automated light sense and flicker perimetry was investigated in 20 eyes of 20 normal subjects. Thresholds were determined at 13 locations in the central visual field. Blurring the retinal image by a small defocus or by slight artificial media opacities causes a measurable reduction in light-difference sensitivity. Flicker fusion frequency, however, is much more resistant to degradation of the retinal image. Artificial pupil size has a similar effect on both light-difference sensitivity and flicker fusion frequency. The present study shows that perimetric methods using temporal threshold criteria should be more suitable for the detection of neuronal damage in the presence of factors disturbing the quality of the retinal image than methods using static criteria.     

A statistical model for the evaluation of sensory tests in glaucoma,depending on optic disc damage

PURPOSE: To analyze the sensitivity of various sensory tests adjusted for glaucomatous optic disc damage. METHODS: In a cross-sectional study, the results of testing of 196 control subjects (age range, 18-69 years) and 308 patients with chronic open-angle glaucoma (age range, 18-70 years) were included. The perimetric mean defect (MD), a temporal contrast sensitivity test (TCS), a spatiotemporal contrast sensitivity test (STCS), the peak time of a blue-on-yellow visual evoked potential (BYVEP), and the amplitude of a pattern-reversal electroretinogram (PERG) were evaluated by a specific logistic regression model. This model included glaucomatous damage, quantified by neuroretinal rim area corrected for disc size, as a covariate of sensitivity. RESULTS: Sensitivity of diagnostic tests increased for all procedures with increasing loss of neuroretinal rim area. With progressing optic disc damage, MD and STCS showed higher sensitivity than did TCS. BYVEP showed a higher sensitivity than PERG in all disease stages. In general, the psychophysical tests were more sensitive than the electrophysiological ones. CONCLUSIONS: The specific model used in this study was an appropriate tool to analyze the sensitivity of several sensory glaucoma tests in relation to disease stage. Moreover, tests that were more sensitive in early disease stages (TCS) and others that were more sensitive in more advanced stages (MD, STCS) were identified.     

Mild systemic hypoxia and photopic visual field sensitivity

Purpose. Flickering stimuli increase the metabolic demand of the retina, making it a sensitive perimetric stimulus to the early onset of retinal disease. We determine whether flickering stimuli are a sensitive indicator of vision deficits resulting from acute, mild systemic hypoxia when compared to standard static perimetry. Methods. Static and flicker visual perimetry were performed in 14 healthy young participants while breathing 12% oxygen (hypoxia) under photopic illumination. The hypoxia visual field data were compared with the field data measured during normoxia. Absolute sensitivities (in dB) were analysed in seven concentric rings at 1°, 3°, 6°, 10°, 15°, 22° and 30° eccentricities as well as mean defect (MD) and pattern defect (PD) were calculated. Preliminary data are reported for mesopic light levels. Results. Under photopic illumination, flicker and static visual field sensitivities at all eccentricities were not significantly different between hypoxia and normoxia conditions. The mean defect and pattern defect were not significantly different for either test between the two oxygenation conditions. Conclusion. Although flicker stimulation increases cellular metabolism, flicker photopic visual field impairment is not detected during mild hypoxia. These findings contrast with electrophysiological flicker tests in young participants that show impairment at photopic illumination during the same levels of mild hypoxia. Potential mechanisms contributing to the difference between the visual fields and electrophysiological flicker tests including variability in perimetric data, neuronal adaptation and vascular autoregulation are considered. The data have implications for the use of visual perimetry in the detection of ischaemic/hypoxic retinal disorders under photopic and mesopic light levels.     

Association between localized visual field losses and thickness deviation of the nerve fiber layer in glaucoma

PURPOSE: To perform a correlation between morphology and function by studying local perimetric field losses and thickness reduction of the nerve layer in corresponding areas. METHOD: Forty-seven patients with "preperimetric" open-angle glaucoma, 95 patients with "perimetric" open-angle glaucoma, and 75 control subjects had perimetric (Octopus) and polarimetric measurements. Criteria for exclusion: optic discs larger than 4 mm, media opacities, polarimetric hourglass pattern in the macular image. Thickness values of the retinal nerve fiber layer were determined in 14 upper and 14 lower sectors (10 degrees each) as well as nasally and temporally (40 degrees each) as provided from the GDx (software version 4000). The healthy control subjects served to determine age-corrected thickness deviation in all sectors. Analyses were calculated in eight nerve fiber bundle related areas. Due to non-linear relationships between perimetric defects and corresponding thickness deviation non-parametric tests were used. RESULTS: Localized visual field defects in the present perimetric patients were highest in upper and lower visual field areas abutting the nasal meridian. Thickness loss of nerve fiber layer however was highest in more circumferential upper and lower nerve fiber bundles. Correlations between local mean defects and deviation of the retinal nerve fiber layer thickness from normals showed a clear association for corresponding areas. The correlation coefficients were significant (P < 0.01) for all arcuate superior and inferior visual field zones except horizontally and not for the area of the lower nasal step. CONCLUSION: The present correspondence map indicates that focal perimetric defects can be identified best polarimetrically if they occur in the arcuate bundles of the visual field. A lack of correspondence was observed in the area of the papillo-macular bundle.     

Stellenwert einer perimetrischen Differenzialdiagnostik beim primären Offenwinkelglaukom

Functional deficits in glaucomatous optic neuropathy are, apart from other disturbances in the visual field, typically detected with achromatic perimetry as a well accepted gold standard. With the development of new perimetric devices and strategies (e.g. short wave perimetry, frequency doubling perimetry and flicker perimetry) individually different patterns of scotomas in the different perimetric devices could be recognized. The reasons for this could be a different sensitivity reaction of the ganglion cell subpopulations to an increased intraocular pressure as well as an influence of the underlying systemic diseases. To obtain a differentiated detection of the functional loss in the visual field in glaucoma, the use of different perimetric methods seems to be reasonable and helpful.     

Balance between pattern and flicker sensitivities in the visual fields of ophthalmological patients.

We measured the balance between visual sensitivities to pattern and to flicker rather than measuring absolute sensitivities to pattern or flicker. The test target was a 2-cycle deg-1 sinewave grating that was counterphase modulated at 8 Hz. Seventeen points in the visual field were tested out to eccentricities of 24 degrees. We examined 10 control subjects, 6 patients with glaucoma 10 with ocular hypertension, and 10 with multiple sclerosis. For controls pattern sensitivity was lower than flicker sensitivity in central vision. The converse held in peripheral vision. The balance between pattern sensitivity and flicker sensitivity was markedly abnormal in part or all of the visual field for many patients. There were examples in all patient groups. In some patients flicker sensitivity was depressed relative to pattern. In others the converse was true. Of 10 patients with ocular hypertension and no perimetric field loss 8 had a significantly abnormal ratio between pattern sensitivity and flicker sensitivity at some point in the visual field. The balance between pattern and flicker sensitivity was more sensitive to visual pathology than absolute sensitivity to either pattern or flicker. We conclude that the relationship between pattern and flicker sensitivity may be more sensitive to visual field damage than is conventional perimetry or visual acuity perimetry.     

The comparison of topical ibopamine 2% with tonography to identify the outflow resistance in eyes with ocular hypertension

BACKGROUND: To evaluate the ability of topical ibopamine 2% to detect outflow resistance by comparing it with the tonography test in eyes with ocular hypertension (OHT). METHODS: 62 eyes with OHT and 33 control eyes were included in this prospective study. Tonography was done manually as a standard outflow facility measurement. We used a C value of 0.18 mul/min/mm Hg or less and a P(o)/C value of 100 and above as a positive tonographic test. The ibopamine test performed on the following day was considered positive if there was an intraocular pressure (IOP) change of at least 3 mm Hg. RESULTS: The sensitivity of the tonography and ibopamine tests was 69 and 53%, respectively, in eyes with OHT. The specificity of both tests was 97%. Although the sensitivity of the tonography test is higher than that of the ibopamine test, the difference between both was not statistically significant in these eyes (p = 0.409). Positive results in tonography were associated with higher IOP, while the results were not dependent on the IOP in the ibopamine test. Both tests together were positive in 33.87% (21 eyes) and negative in 11.29% (7 eyes) in 62 eyes with OHT. CONCLUSION: This study revealed that the ibopamine provocation test can detect outflow system resistance in eyes with OHT comparable with tonography which is a traditional outflow facility measurement. Ibopamine, however, can detect the eye with outflow impairment by a different and IOP-independent way, while tonography depends on IOP.     

A basis for customising perimetric locations within the macula in glaucoma

Purpose

It has been recognised that the 24‐2 grid used for perimetry may poorly sample the macula, which has been recently identified as a critical region for diagnosing and managing patients with glaucoma. We compared data derived from patients and controls to investigate the efficacy of a basis for customising perimetric locations within the macula, guided by en face images of retinal nerve fibre layer (RNFL ) bundles.

Methods

We used SD ‐OCT en face montages ( www.heidelbergengineering.com ) of the RNFL in 10 patients with glaucoma (ages 56–80 years, median 67.5 years) and 30 age‐similar controls (ages 47–77, median 58). These patients were selected because of either the absence of perimetric defect while glaucomatous damage to the RNFL bundles was observed, or because of perimetric defect that did not reflect the extent and locations of the glaucomatous damage that appeared in the RNFL images. We used a customised blob stimulus for perimetric testing (a Gaussian blob with 0.25° standard deviation) at 10‐2 grid locations, to assess the correspondence between perimetric defects and damaged RNFL bundles observed on en face images and perimetric defects. Data from the age‐similar controls were used to compute total deviation (TD ) and pattern deviation (PD ) values at each location; a perimetric defect for a location was defined as a TD or PD value of ?0.5 log unit or deeper. A McNemar's test was used to compare the proportions of locations with perimetric defects that fell outside the damaged RNFL bundles, with and without accounting for displacement of ganglion cell bodies.

Results

All patients but one had perimetric defects that were consistent with the patterns of damaged RNFL bundles observed on the en face images. We found six abnormal perimetric locations of 2040 tested in controls and 132 abnormal perimetric locations of 680 tested in patients. The proportions of abnormal locations that fell outside the damaged RNFL bundles, with and without accounting for displacement of the ganglion cell bodies were 0.08 and 0.07, respectively. The difference between the two proportions did not reach statistical significance (p  = 0.5 for a one‐tailed test).

Conclusions

We demonstrated that it is effective to customise perimetric locations within the macula, guided by en face images of the RNFL bundles. The perimetric losses found with a 10‐2 grid demonstrated similar patterns as the damaged RNFL bundles observed on the en face images.

     

The photopic negative response of the blue-on-yellow flash-electroretinogram in glaucomas and normal subjects

The photopic negative response of the flash-electroretinogram driven by the middle- and long-wavelength cones has been shown to be reduced in non-human primates with experimental glaucoma and in human patients with glaucoma. The photopic negative response for the blue-sensitive response has been studied using a blue-green silent-substitution-technique on a red background. The aim of this study was to re-evaluate the value of the photopic negative response of the blue-sensitive pathway in glaucoma using a conventional flash-electroretinogram. In 37 eyes of 37 controls (age: 53 +/- 13.6 years) and 37 eyes of 37 patients with open-angle glaucoma of different perimetric visual field defects (age: 58.3 +/- 10 years; MD: 11.7 +/- 6.7 dB) of the Erlangen glaucoma registry Ganzfeld flash-electroretinograms (LKC, UTAS 3000) were recorded using blue Xenon-flashes of increasing photopic luminance (0.013, 0.018, 0.030, and 0.052 cd s/m(2); 440 nm) on a bright yellow background (238 cd/m(2); 550 nm) after 2 min of light adaptation. Amplitudes and implicit times of the photopic negative response and of L&M-cone- and S-cone-driven b-waves were compared between glaucomas and controls for all flash energies (unpaired t-test). The amplitudes of the photopic negative response were significantly reduced in glaucoma patients for all flash energies (P < 0.001). The implicit times of L&M-cone-driven b-wave (0.013, 0.018, 0.030, and 0.052 cd s/m(2)) and S-cone-driven b-wave (0.030 and 0.052 cd s/m(2)) were significantly prolonged in glaucoma patients (P < 0.05). The changes in these implicit times, however, are very small (1.5 ms or less). The other measures did not differ significantly. The amplitude of the photopic negative response and the implicit times of the L&M-cone and S-cone b-wave in the same responses of the blue-on-yellow flash-electroretinogram are potentially useful in the evaluation of inner-retinal function in glaucoma.     

Influence of learning effect on blue-on-yellow perimetry

PURPOSE. Some studies have found that a significant blue-on-yellow perimetry (B/YP) learning effect exists in patients with ocular hypertension (OHT) or open-angle glaucoma who were experienced in standard automated perimetry. However, very little is known about the B/YP learning effect in normal subjects and patients without previous white-on-white perimetry (W/WP) experience. Meanwhile, it is unclear whether the B/YP learning effect is influenced by age and refraction. METHODS. Twenty healthy subjects, 26 OHT and 14 primary open angle glaucoma (POAG) patients, underwent three full-threshold B/YP tests at intervals of 7 to 21 days. Of the 60 subjects, 38 had no previous W/WP experiences, 22 had previous W/WP experiences for at least two times. The parameters investigated to detect a learning effect were the perimetric indices and the test duration (TD). RESULTS. Learning effects were demonstrated for mean deviation (MD), pattern standard deviation (PSD), short-term fluctuation (SF), and TD. Significant differences were found between the MD, PSD, SF, and TD of the first test and those of the second and third tests (p<0.05). However, no difference was found between those parameters of the second and third tests. No statistically significant differences were noted in terms of MD1st-2nd, MD1st-3rd, PSD1st-2nd, PSD1st-3rd, TD1st-2nd, and TD1st-3rd between the group with W/WP experience and the group without previous W/WP experience (p>0.05). No statistically significant differences were noted in terms of those parameters among the normal subjects and the patients with OHT or POAG (p>0.05). No significant difference was found in the B/YP learning effect among various age groups (p>0.05) and among various refraction groups (p>0.05). CONCLUSIONS. A significant learning effect was observed between the first and the second or third tests and the perimetric indices appeared improved at full-threshold B/YP. The previous W/WP experience and the subject age and refraction did not influence the B/YP learning effect. This above all should be taken into account when considering the clinical use of this test to avoid erroneous diagnostic conclusions.