Glaucoma detection is facilitated by luminance modulation of the global flash multifocal electroretinogram

PURPOSE: To investigate the variation of retinal electrophysiological function in glaucoma by using the global flash multifocal electroretinogram (mfERG) stimulation with altered differences in the stimulus luminance of the multifocal flashes, in an attempt to alter the levels of inner retinal contributions. METHODS: The mfERG was assessed with a visual stimulus in steps of four video frames, which consisted of 103 scaled hexagonal elements followed by a dark frame, global flash, and dark frame. The localized luminance difference was set at 96%, 65%, 49%, or 29% stimulus contrast. Thirty subjects with glaucoma and 30 age-matched normal subjects were recruited for visual field and mfERG measurements. RESULTS: This stimulus induces complex local first-order responses with an early direct component (DC) and a later induced component (IC). The luminance-modulated response functions of the DC and IC responses showed markedly different behavior. The peripheral IC showed a linear dependence on luminance difference, whereas the peripheral DC was saturated for higher luminance differences. This saturation became less obvious in subjects with glaucoma, mostly because of greater reduction of the response amplitude in the mid luminance-difference level. An "adaptive index" was calculated from the luminance-difference dependence of the peripheral DC, and it showed a sensitivity of 93%, with a specificity of 95% for differentiating normal from glaucomatous eyes, and also had a significant correlation (r = 0.58) with the glaucomatous visual field defect. CONCLUSIONS: The peripheral DC luminance-modulated response function is altered by the adaptive mechanism that is induced by the global flash; the reduction of the adaptive index may thus relate to an abnormal adaptive mechanism, presumably due to inner retinal damage. Glaucoma appears to produce large reductions of the adaptive index which correlate with field defects.     

Adaptation responses in early age-related maculopathy

PURPOSE: To investigate the global-flash multifocal electroretinogram (mfERG) in early age-related maculopathy (ARM). METHODS: Thirty-two eyes from 20 healthy control subjects and 12 age-matched subjects with early ARM were investigated with the conventional and the global-flash mfERG. Early ARM subjects were graded according to an international grading system. The conventional mfERG consisted of 103 hexagons flickering according to a pseudorandom m-sequence. The global-flash mfERG paradigm used four frames starting with the conventional m-sequence stimulation, followed by a dark frame, a global flash, and another dark frame. The responses include a direct response (DR) and a later induced component (IC). The first-order kernel peak-to-trough response densities of the conventional mfERG (N1P1), the global-flash DR and IC, and the implicit times of the conventional P1, global-flash DR, and IC peak were analyzed after averaging the results into five groups according to five field locations: a central area and four quadrants. RESULTS: There was a significant reduction of the global-flash mfERG DR response density (P < or = 0.05) in the early ARM group compared with the control group. Neither the IC response density nor DR and IC implicit times were significantly impaired. However, the superior retina showed longer implicit times than did the inferior retina for the DR in the early ARM group. There was no significant correlation between funduscopic features and the central averaged responses of the global-flash mfERG (for the DR response density: r = -0.19, P = 0.3, or for the DR implicit time: r = -0.18, P = 0.3). None of the conventional mfERG parameters was significantly different between the two groups. CONCLUSIONS: The global-flash mfERG detects deficits in early ARM before the conventional mfERG. Retinal ischemia may play a role in producing function impairment in ARM.     

Multifocal objective perimetry in the detection of glaucomatous field loss.

PURPOSE: To test the ability of a new type of multifocal objective perimetry to identify glaucomatous visual field defects. METHODS: A multichannel visual evoked potential was recorded using the ObjectiVision Accumap perimeter. One hundred patients (age, 62.2 +/- 9.8 years, mean MD -6.5 +/- 4.17 dB) with open-angle glaucoma and confirmed glaucomatous visual field defects were tested and compared with the normal database of 100 normal subjects (age, 58.9 +/- 10.7 years). Both eyes were tested, but for determining sensitivity the eye with the lesser field defect was chosen if both qualified. The amplitude and intereye asymmetry coefficient for each zone of the field were calculated. A mean amplitude and multifocal objective perimetry severity index was calculated for each subject. RESULTS: In 95 of 100 (95%) patients with glaucoma Humphrey field defects were correlated with visual evoked potential amplitude reductions identifying a cluster of three or more abnormal zones. In two of five remaining patients with glaucoma the defect was detected on the intereye asymmetry analysis. Topographic location was well correlated with Humphrey fields. Mean amplitude was significantly reduced in 86 of the glaucoma cases (86%). The glaucoma severity index was abnormal in 93 glaucoma cases and showed a correlation with Humphrey MD (r = 0.67 right eyes, 0.69 left eyes). In 37 glaucoma cases with no scotoma by definition in the fellow eye, 22 (59.4%) had an abnormal multifocal objective perimetry, whereas only eight had some other aspect of their Humphrey visual field flagged as abnormal. CONCLUSIONS: Multifocal objective perimetry can assess the visual field and identify glaucomatous visual field defects. It may have the potential for identifying defects earlier than conventional perimetry.     

Thinning of the papillomacular bundle in the glaucomatous eye and its influence on the reference plane of the Heidelberg retinal tomography.

PURPOSE: To measure the thickness of the papillomacular bundle in glaucomatous eyes with good visual acuity and to evaluate the influence of an adjusted reference plane on the Heidelberg retinal tomography result. METHODS: The thickness of the papillomacular bundle was measured with optical coherence tomography in both eyes of eight patients with asymmetric glaucoma. The eye with less glaucomatous damage with normal visual field served as the control. The difference in the thickness of the papillomacular bundle between the control eye and the glaucomatous eye was used to correct the reference plane of Heidelberg retinal tomography. RESULTS: The thickness of the papillomacular bundle in glaucomatous eyes was reduced (P = 0.00037) and was 33.9 +/- 16.5 microm thinner than control eyes. A corrected reference plane in Heidelberg retinal tomography caused an increased classification value (-0.683 +/- 0.164), implying that more glaucoma damage was detected after the correction. In one case the value was shifted from normal to glaucomatous after an adjustment of the reference plane. CONCLUSION: The thickness of the papillomacular bundle is decreased in glaucomatous eyes, though these eyes have good visual acuity. Evaluation of glaucoma with Heidelberg retinal tomography using the standard reference plane may underestimate the glaucoma damage.     

Central corneal thickness in congenital glaucoma

PURPOSE: The aim of this study was to compare central corneal thickness between eyes with congenital glaucoma and normal fellow eyes in unilateral glaucoma or less affected fellow eyes in bilateral glaucoma. METHODS: Eyes of consecutive phakic children with congenital glaucoma and previous glaucoma surgery were examined under chloral hydrate. Complete ophthalmologic examination, central corneal thickness (CCT), axial length, and corneal diameter measurements were performed. Patients were included in the study if presented with intraocular pressure (IOP) less than 21 mm Hg and no biomicroscopic signs of corneal edema. RESULTS: Nine patients were included in the study. The mean CCT in the more affected eye/glaucomatous eye was 522.3 +/- 65.2 microm and in the less affected eye/healthy eye was 579.7 +/- 44.5 microm. This difference was statistically significant (P = 0.0013). CONCLUSION: CCT was significantly thinner in glaucomatous eyes than in normal fellow eyes in phakic children with congenital glaucoma. This finding may be another confounding factor when measuring IOP in these patients.     

The Peritest automatic perimeter in screening for glaucomatous visual field defects

The ability of the Peritest to screen for glaucomatous defects of the visual field was studied by using this automatic perimeter to examine the visual fields of 69 eyes with chronic open-angle glaucoma and 46 normal eyes after manual perimetry had been performed. The Peritest correctly identified 62 (90%) of the glaucomatous eyes as having visual field abnormalities; the other 7 eyes (10%) had false-positive results. Of the 46 normal eyes, 36 (78%) were correctly identified as having normal visual fields; the other 10 eyes (22%) were incorrectly identified as having visual field abnormalities. Thus, the overall rate with which eyes were correctly classified as having normal or abnormal visual fields was 85%, and the rate with which fields were falsely identified as having glaucomatous abnormalities was 15%.     

Sensitivity and specificity of the Swedish interactive threshold algorithm for glaucomatous visual field defects

PURPOSE: To determine the sensitivity and specificity of two new visual field algorithms in detecting glaucomatous visual field defects: (1) Swedish interactive threshold algorithm (SITA) standard and (2) SITA fast. DESIGN: Prospective observational case series. PARTICIPANTS: Ninety normal subjects and 82 glaucoma patients. TESTING: Central 30 degrees fields were performed with the Humphrey visual field analyzer 30-2 program (Humphrey Systems, Dublin, CA) using full threshold, SITA standard, and SITA fast algorithms on the same day for two or more sessions within a 1-month period. MAIN OUTCOME MEASURES: Sensitivity and specificity in detecting glaucomatous visual field defects with SITA standard and SITA fast using full threshold testing as the reference standard. RESULTS: The sensitivity of SITA standard and SITA fast in detecting glaucomatous defects overall was 98% and 95%, respectively. In the subset of mild glaucomatous field defects (26 patients), sensitivity of SITA standard was 92% versus 85% with SITA fast. Sensitivity was 100% for both algorithms in moderate to severe glaucomatous defects. Specificity for glaucoma defects using SITA standard and SITA fast was 96% for both algorithms. SITA standard reduced test-taking time from full threshold by 52% in normal subjects and 47% in glaucoma patients (P < 0.001). SITA fast reduced test-taking time by 72% in normal subjects and 65% in glaucoma patients (P < 0.001). Mean deviation values were 0.4 dB and 0.8 dB better in SITA standard and SITA fast fields, respectively, in normal subjects (P < 0.001), and 0.7 dB and 1.2 dB in SITA standard and SITA fast fields, respectively, in glaucoma patients (P < 0.001) compared with full threshold values. CONCLUSIONS: The new algorithms for measuring visual fields, SITA standard and SITA fast, have excellent sensitivity and specificity for glaucomatous visual field loss with considerable savings in time.     

The use of RADAAR (ratio of rim area to disc area asymmetry) in detecting glaucoma and its severity

BACKGROUND: In a previous study it was shown that the asymmetry of rim area and disc area of fellow eyes expressed as a ratio (rim area to disc area asymmetry ratio [RADAAR]) was associated with the diagnosis of glaucoma in patients with highly asymmetric disease. Furthermore, this ratio was able to distinguish these patients from groups of glaucoma suspects and subjects without glaucoma. The purpose of this study was to investigate whether the RADAAR correlates with the diagnosis and severity of glaucoma in a large glaucomatous population. METHODS: We reviewed the records of 140 randomly selected patients with open-angle, normal-tension or pseudoexfoliative glaucoma evaluated at the glaucoma service of a tertiary care centre in Philadelphia between January 1996 and April 2000. Heidelberg Retina Tomograph (HRT) disc area, rim area, cup-to-disc area ratio, pattern-standard deviation and mean deviation as well as maximum intraocular pressure (IOP) were recorded. Disc staging and visual fields determined severity of glaucoma, and fellow eyes were classified as "better" or "worse." RESULTS: The RADAAR was significantly correlated with IOP (r = 0.23, p < 0.03), mean deviation (r = -0.22, p < 0.02), cup-to-disc area ratio (r = 0.19, p < 0.03) and disc stage of glaucomatous optic nerve damage (r = 0.17, p < 0.05) in "worse" eyes. RADAAR groups were also correlated with fellow-eye differences in mean deviation (p < 0.05) and cup-to-disc area ratio (p < 0.02). INTERPRETATION: The RADAAR, a new HRT-derived measure of asymmetry in fellow eyes, is associated with the diagnosis of glaucoma and its severity.     

Quantitative evaluation of the optic nerve head in patients with unilateral visual field loss from primary open-angle glaucoma

Measurable structural alterations of the optic nerve head may precede visual field abnormalities in early open-angle glaucoma. The authors studied the optic nerve heads of 10 patients with unilateral visual field loss from primary open-angle glaucoma, and 12 age- and sex-matched normal subjects. Topographic optic nerve head parameters were measured with a system of computerized image analysis (Rodenstock Analyzer, G. Rodenstock Instrumente GMBH, Munich, W. Germany). In patients with asymmetric primary open-angle glaucoma, eyes with normal visual fields had a slightly larger mean (+/- standard error of the mean) disc rim area (0.90 +/- 0.04 mm2) than eyes with glaucomatous visual field defects (0.78 +/- 0.05 mm2). However, both sets of eyes in the asymmetric primary open-angle glaucoma patients had smaller mean disc rim areas (P less than 0.0007) than did the control group (1.27 +/- 0.09 mm2). These findings support the hypothesis that loss of the optic disc rim can be detected before perimetric abnormalities develop in primary open-angle glaucoma.     

Clinical comparison of pascal dynamic contour tonometry and goldmann applanation tonometry in asymmetric open-angle glaucoma

PURPOSE: To investigate and compare the relationships between glaucomatous visual field loss and intraocular pressure (IOP) as measured by both Pascal dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT). PATIENTS AND METHODS: All primary open-angle glaucoma and normal tension glaucoma patients seen between July 2005 and June 2006 with at least 2 sets of good-quality, bilateral DCT and GAT measurements were retrospectively identified. Additional inclusion criteria required that all subjects had repeatable, asymmetric glaucomatous visual field loss that corresponded with asymmetric glaucomatous optic neuropathy. After mean IOP values were computed and visual fields were scored using Advanced Glaucoma Intervention Study (AGIS) criteria, paired-eye comparisons were conducted using right versus left eyes and higher versus lower AGIS-score eyes. RESULTS: Sixty-seven (42 primary open-angle glaucoma, 25 normal tension glaucoma) subjects met all criteria for study inclusion. Per paired t test, mean DCT-IOP was significantly higher in the higher AGIS-score eyes compared with the lower AGIS-score eyes (16.3 vs. 15.5 mm Hg, P=0.004), whereas GAT-IOP was not significantly different in these same eyes (14.5 vs. 14.4 mm Hg, P=0.56). Mean IOP difference between the 2 methods was significantly larger in higher versus lower AGIS-score eyes (P<0.001), and 72% of the subjects demonstrated larger intermethod IOP differences in their higher AGIS-score eye compared with their lower AGIS-score eye (P<0.001; 95% confidence interval: 0.59-0.82). Multivariate linear regression analysis revealed that AGIS-score differences between eyes were independently associated with both intermethod IOP differences between eyes (P=0.004) and central corneal thickness (CCT) differences between eyes (P=0.04). CCT, however, was not associated with intermethod IOP differences within or between eyes. CONCLUSIONS: These findings suggest that DCT-IOP is correlated with glaucomatous damage, and moreover, DCT-IOP is more closely related to extent of glaucoma damage than is GAT-IOP. The most likely explanation for these results is that GAT-IOP systematically underestimates IOP compared with DCT-IOP. Our findings also support the hypothesis that corneal biomechanical factors other than CCT are major confounders of applanation tonometry measurements.     

The frequency distribution of earliest glaucomatous visual field defects documented by automatic perimetry

2500-3000 eyes with ocular hypertension, with or without established glaucoma in the fellow eye, were followed with automatic perimetry for several years. Forty-five eyes showed a documented change from repeated normal fields to reproducible glaucomatous visual field loss. The location of the defective points in the first pathological field of each eye was registered. The resulting frequency distribution is shown and discussed.     

Visual field progression in patients with initially unilateral visual field loss from chronic open-angle glaucoma

PURPOSE: To investigate visual field progression in patients with initially unilateral glaucomatous visual field loss, and to determine risk factors for progression. DESIGN: Retrospective observational case series. PARTICIPANTS: Forty-eight consecutive patients with primary open-angle glaucoma, pseudoexfoliative glaucoma, or pigmentary glaucoma, seen over an 18-month period, who initially had unilateral visual field loss as defined by use of modified Anderson criteria. Patients were followed with standard Humphrey perimetry for a minimum of 2 years. METHODS: Progression was defined by use of modified Anderson criteria, and Advanced Glaucoma Intervention Study (AGIS) and Collaborative Initial Glaucoma Treatment Study scores. MAIN OUTCOME MEASURE: Visual field progression. RESULTS: Three patients (6.2%) had fellow eye progression over a mean follow-up of 76 months and duration of disease of 8.7 years. Fellow eye progression correlated with progression of the first-affected eye (P = 0.044). Ten patients (21%) had progression of the first-affected eye; these eyes had a larger initial cup/disc ratio compared with stable eyes (P = 0.041). Increasing initial AGIS score was associated with progression (P: = 0.003). Kaplan-Meier survival analysis estimated the risk of progression at 5 years to be 25% in first-affected eyes and 7.2% in fellow eyes. CONCLUSIONS: In this population, the risk of fellow eye progression in patients with initially unilateral visual field loss from open-angle glaucoma is low. Progression is higher in eyes with visual field loss at initial testing, and the risk of progression increases as the level of initial visual field loss increases.     

Assessing Responses of the Macula in Patients with Macular Holes using a New System Measuring Localized Visual Acuity and the mfERG

Purpose: To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. Methods: We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21° diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45° diameter using the mfERG. Results: In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21° diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8° in affected eyes. In the central 2°, 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Conclusions: Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).     

Multifocal electroretinograms in early primary open-angle glaucoma

PURPOSE: To determine the utility of multifocal electroretinograms (mfERGs) in patients with early primary open-angle glaucoma (POAG) with unilateral visual field abnormalities. METHODS: mfERGs were recorded from 24 eyes of 12 cases of early POAG (stage I for 1 eye and stage II for the other eye on the Kosaki scale). The implicit times and amplitudes of the second-order kernel summed for the whole visual field, for the superior and inferior hemi-fields, and for quadrantic fields of the stage I and stage II eyes were compared. RESULTS: Neither the first- nor the second-order kernels of the mfERGs showed any changes reflecting glaucomatous visual field abnormalities. The implicit times and amplitudes of the second-order kernel summed for the whole visual field, the superior and inferior hemi-visual fields, and quadrantic visual fields of the stage I and stage II eyes were also not significantly different. CONCLUSIONS: We conclude that because the second-order kernel of the mfERG does not correlate with the visual field abnormality in early POAG, the second-order kernel of the mfERG that can be recorded at present is highly unlikely to reflect the function of the ganglion cells in the inner retinal layers.     

Glaucomatous damage in normotensive fellow eyes of patients with unilateral hypertensive pseudoexfoliation glaucoma: normotensive pseudoexfoliation glaucoma?

BACKGROUND: The objective of the study was to investigate the prevalence of glaucomatous damage in normotensive fellow eyes of patients with unilateral high-tension pseudoexfoliation (PX) glaucoma. METHODS: Initial examination records of 111 patients with unilateral PX glaucoma with intraocular pressure (IOP) > or = 22 mmHg in the hypertensive eye and IOP < or = 21 mmHg in the normotensive fellow eye without any prior antiglaucomatous treatment were retrospectively studied. Visual field and optic disc examination results were evaluated for glaucomatous damage in the normotensive eyes. RESULTS: Glaucomatous changes were detected in 45 of the 111 fellow eyes (40%). The damage was mild in 25 eyes (22%), moderate in 18 eyes (16%), and severe in 2 (2%). The factors significantly associated with glaucomatous findings in the normotensive eyes were clinical detection of PX, higher age (> or =70 years), higher maximal IOP (> or =18 mmHg) and wider IOP fluctuation (> or =6 mmHg) in the univariate analyses. In the multivariate analysis, associated factors remained as higher maximal IOP (odds ratio = 7.92, confidence interval = 2.82-22.23, P < 0.001) and wider IOP fluctuation (odds ratio = 5.67, confidence interval = 2.05-15.74, P = 0.001). CONCLUSION: Normotensive fellow eyes of patients with unilateral high-tension PX glaucoma are under significant risk of glaucomatous damage, related with the level and the fluctuation range of IOP.     

Polarimetric measurement of retinal nerve fiber layer thickness in glaucoma diagnosis

PURPOSE: To evaluate reliability and diagnostic value of polarimetric measurements of the retinal nerve fiber layer (RNFL) thickness in the diagnosis of glaucoma. METHODS: The study included 81 eyes with perimetric glaucoma with glaucomatous changes of the optic disc and visual field defects; 52 eyes with preperimetric glaucoma with glaucomatous optic disc abnormalities and normal achromatic visual fields; and 70 normal eyes. For determination of reliability, four examiners repeated polarimetric measurements five times in ten normal subjects. RESULTS: The polarimetric variables were significantly correlated with increasing mean visual field defect and decreasing neuroretinal rim area. In correlation analyses with visual field defects, correlation coefficients were highest for the variable "superior/nasal ratio" and "the Number," a variable calculated by the neural network of the device. In correlations with neuroretinal rim area, correlation coefficients were highest for measurements of the inferior nerve fiber layer thickness. The preperimetric glaucoma group and the control group differed significantly in the variables "superior/nasal ratio" and "the Number" and, to a smaller degree, in the variables "superior/temporal ratio" and "superior/inferior ratio." The Number variable had a sensitivity of 82% and 58% at a predefined specificity of 80% in separating perimetric glaucoma patients and preperimetric glaucoma patients, respectively, from control subjects. Reproducibility of the polarimetric measurements ranged between 70% and 89%. CONCLUSION: Polarimetric measurements of the RNFL thickness can detect glaucomatous optic nerve damage in patients with visual field loss, and in some patients with preperimetric glaucomatous optic nerve damage. Considering the fast performance, easy handling, and low maintenance costs, RNFL polarimetry may be helpful in glaucoma diagnosis.     

The effect of contrast and luminance on mfERG responses in a monkey model of glaucoma

PURPOSE: To evaluate the effect of contrast and luminance attenuation on the multifocal electroretinogram (mfERG) responses of normal and glaucomatous eyes of cynomolgus monkeys. METHODS: Nine adult male cynomolgus monkeys with unilateral experimentally induced glaucoma were used. Hypertension-induced damage was confirmed by tomography of the optic disc. mfERGs were recorded with five different stimulus contrasts and/or luminance settings. The first-order and the first slice of second-order responses were analyzed. RESULTS: Waveforms of normal and glaucomatous eyes differed in shape and amplitude. Second-order responses contributed to first-order responses of the signals in the normal eyes, but made a negligible contribution to the signals in the glaucomatous eyes. Contrast and luminance attenuation affected both first- and second-order responses. The differences between signals in normal and glaucomatous eyes were sufficiently large for an unsupervised clustering algorithm to achieve accurate segregation. CONCLUSIONS: The observations in this study indicate that outer and inner retinal generators participate in first-order mfERG responses and that both inner and outer retinal contributors respond to contrast and luminance changes in stimulus. The hypertension-induced changes in the mfERG furthermore suggest damage to both inner and outer retina.     

Detection of early glaucoma with optical coherence tomography (StratusOCT)

PURPOSE: To evaluate the performance of optical coherence tomography (StratusOCT) for discriminating eyes with early glaucoma from normal eyes. METHODS: Thirty eyes with established early glaucomatous visual field defects (EGVF group), 30 eyes with evidence of early glaucomatous optic neuropathy with normal standard achromatic perimetry [early glaucoma by disc (EGD)], and 33 age-matched normal eyes with good quality StratusOCT nerve fiber layer (NFL) images were enrolled. Average NFL thickness and NFL thickness at quadrants and sectors, areas under receiver operator characteristic curves, and sensitivities at 80% and 90% specificity were evaluated. RESULTS: The average (+/-SD) mean deviation in the EGVF group was -3.4 (+/-1.7) dB. Receiver operator characteristic curves showed areas under the curve (AUC) for NFL thickness in the superior quadrant (AUC=0.75+/-0.07) and in the inferior quadrant (AUC=0.94+/-0.03) to be the best StratusOCT parameters for discrimination of normal controls from EGD and EGVF eyes, respectively. The best parameter for detection of EGD eyes at 80% and 90% specificities was NFL thickness at superior quadrant (51% and 36% sensitivities, respectively). The best parameter for detection of EGVF eyes at 80% and 90% specificities was NFL thickness in the inferior quadrant (90% and 87% sensitivities, respectively). CONCLUSIONS: Optical coherence tomography (StratusOCT) showed good sensitivity and specificity in a group of glaucoma patients with early visual field loss. In patients with normal visual fields in whom the optic disc appeared glaucomatous to glaucoma specialists, half were confirmed to have StratusOCT findings consistent with damage from glaucoma.     

Color Doppler imaging study of retrobulbar hemodynamics in chronic angle-closure glaucoma

PURPOSE: To evaluate the retrobulbar hemodynamics in patients with chronic angle-closure glaucoma (CACG) by using color Doppler imaging (CDI) and to correlate the degree of glaucomatous visual field loss with the hemodynamic parameters. DESIGN: Prospective case series. PARTICIPANTS AND CONTROLS: Twenty-six Chinese patients with CACG and 26 age-matched and gender-matched normal subjects were recruited. All CACG patients had history of chronic intraocular pressure (IOP) elevation and asymmetric visual field defects between their fellow eyes. After receiving laser peripheral iridotomy and/or filtration surgery, all of them had bilateral medication-free controlled IOP before enrolling into the study. METHODS: Each subject underwent CDI measurement in the central retinal artery (CRA) and the nasal and temporal short posterior ciliary arteries (PCA). Visual fields of the CACG patients were obtained with Humphrey 24-2 program. The visual field defects were scored with the Advanced Glaucoma Intervention Study (AGIS) system. For each CACG patient, the eye with lower AGIS score was defined as the better eye and the eye with higher score as the worse eye. MAIN OUTCOME MEASURES: Peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) were determined. RESULTS: The EDV in the CRA and the temporal PCA was decreased significantly (P = 0.041 and 0.023, respectively) in the worse eyes of CACG patients compared with those in the control eyes. The better eyes of CACG patients showed no significant change in hemodynamic parameters compared with the control eyes. While comparing the fellow eyes of CACG patients, the worse eyes had significantly lower EDV in the temporal PCA (P = 0.012) than the contralateral better eyes. In 11 CACG patients with a difference of at least 8 in AGIS visual field scores between their fellow eyes, the worse eyes had significantly lower EDV (P = 0.041) in the CRA and lower PSV (P = 0.018) and EDV (P = 0.018) in the temporal PCA compared with those in the contralateral eyes. In multivariate regression analysis, the AGIS scores were significantly correlated with the PSV in the CRA (P = 0.015) and with the EDV (P < 0.001) and RI (P = 0.027) in the temporal PCA in patients with CACG. CONCLUSIONS: Patients with well-controlled CACG may have decreased retrobulbar blood flow velocities and increased vascular resistance in the CRA and temporal PCA. The degree of retrobulbar hemodynamic impairment was well correlated with the degree of glaucomatous visual field loss.     

Nerve fiber layer thickness in glaucoma patients with asymmetric hemifield visual field loss

PURPOSE: To investigate the presence of retinal nerve fiber layer (RNFL) thinning and determine the relationship between RNFL thickness and visual field sensitivity loss in glaucoma patients with asymmetric hemifield visual field loss. PATIENTS AND METHODS: Thirty glaucoma patients with asymmetric hemifield visual field loss and 30 normal control subjects were included in the study. RNFL thickness was measured by optical coherence tomography and visual field sensitivity was measured by automated perimetry. Glaucoma patients with advanced visual field loss restricted to 1 hemifield and early or absent glaucomatous field loss in the other hemifield on the basis of the visual field data were included. Visual field sensitivity and mean deviation (MD) were averaged separately in each of the 2 hemifields. The hemifields in each eye were categorized as early (MD>or=-6 dB) and advanced (MD<-6 dB) glaucomatous hemifields. RESULTS: RNFL thickness measurements in corresponding (eg, superior peripapillary quadrant with inferior hemifield) advanced glaucomatous hemifields (59+/-16 microm) were significantly (P<0.001) lower than in corresponding early glaucomatous hemifields (90+/-25 microm). The mean RNFL thickness in corresponding advanced and early glaucomatous hemifields were significantly lower than in normal control subjects (P<0.0001). On the basis of the normative database supplied by optical coherence tomography software, 100% and 43% of eyes had abnormal RNFL thickness in corresponding advanced and early glaucomatous hemifields, respectively. A linear correlation was found between RNFL thickness and MD in the early (r=0.6; P<0.001) and advanced (r=0.5; P=0.007) glaucomatous hemifields. CONCLUSIONS: RNFL thinning was present in corresponding hemifields of glaucomatous eyes with minimal visual field defect and correlated with visual field sensitivity loss. Measurement of RNFL thickness has potential for detection of early nerve fiber loss owing to glaucoma.