Optic Nerve Head Measurements Research Articles

Optical Coherence Tomography Measurement of Retinal Nerve Fibre Layer, Optic Nerve Head and Macula in Normal Subjects

The aim of the study was to evaluate the variation in retinal nerve fibre layer (RNFL), optic nerve head (ONH) and macular measurements in healthy Turkish subjects using Stratus optical coherence tomography (OCT). The design is a cross-sectional study of 398 eyes in 199 normal subjects aged between 5 and 70 years. The participants underwent a detailed ophthalmologic examination including imaging with Stratus OCT. RNFL, optic disc and macula fast scan methods were used to obtain the peripapillary RNFL thickness, ONH and macular parameters. The effects on the findings of age, gender and laterality of the eye tested were assessed. The average RNFL thickness and the thickness measured in the superior and temporal quadrants were statistically significantly negatively correlated with age. Similar results were found for mean macular thickness, macular RNFL thickness and for total macular volume. There was no effect of age on ONH measurements. The RNFL thickness in the temporal quadrant was significantly greater in females than in males (p<0.05). The mean macular thickness in 1–3 mm was greater in males than in females (p<0.05). The nasal RNFL thickness was significantly thicker in the right eyes than in the left eyes (p<0.05). We conclude that, in healthy subjects, as age increases there is a significant reduction in peripapillary and macular RNFL thickness and in macular thickness and volume. The hypothesis that RNFL and macular measurements are not symmetrical between the two eyes merits further study.

Correlation between Visual Evoked Potentials and Optical Coherence Tomography Measurements of Optic Nerve Head, Retinal Head, Retinal Nerve Fibre Layer and Macula in Behçet Disease

The aim of the study was to investigate whether a correlation can be found between retinal structural evaluation (optic nerve head (ONH) evaluation, retinal nerve fibre layer thickness, and macular thickness and volume) and functional (visual evoked potentials) (VEPs) findings in Behçet disease (BD) without neurological manifestations. 13 patients with BD and 12 healthy subjects of a similar age were studied. The retinal nerve fibre layer(RNFL) thickness, ONH parameters, macular thickness and volume were measured by commercially available Stratus optical coherence tomography(OCT). Peak latencies of N75, P100, and N145 responses were measured by pattern visual evoked potential examination. The mean disease duration in years was 2,50 ± 0,48 (standard error of mean; SEM). The N75 latencies of the VEP responses were prolonged and the amplitudes lower than controls (p<0.05). The mean RNFL average thickness was significantly reduced in BD patients (104.50 ± 13.88 microns) when compared with those of control subjects (115.85 ± 13.32microns) (p<0.05). The RNFL loss was statistically significant in the superior, temporal and inferior quadrants (p<0.05). There was no significant difference between groups with respect to the ONH or the macular thickness and volume parameters (p>0.05). Average RNFL thickness was significantly correlated to neither the VEP measurements nor the duration of BD (p>0.05). We conclude that the present study suggests a significant reduction in peripapillary RNFL in patients with BD measured by OCT. Although patients in the BD cohort studied here had neither ocular nor neurological involvement prolonged latency and reduced amplitude of the VEP was found. OCT measurements of the retinal nerve fibre layer and VEP measurements may have roles in detecting subclinical neurological involvement in BD.

Optic nerve head analysis of superior segmental optic hypoplasia using Heidelberg retina tomography

PurposeTo evaluate the optic disc characteristics of eyes with superior segmental optic hypoplasia (SSOH) using the Heidelberg retina tomograph (HRT).Patients and methodsThirteen eyes of 13 Japanese patients with SSOH were studied with the HRT (software version: 3.0). The group included six males and seven females, with a mean age of 34.7 years. Six optic disc parameters in the six sectors derived from the patients with SSOH were compared with those of 13 eyes of 13 normal controls. In addition, the diagnostic classification performance of the Frederick S Mikelberg (FSM) discriminant function, glaucoma probability score (GPS), and Moorfields regression analysis (MRA) were assessed.ResultsWhen compared with normal subjects, many of the optic disc parameters were significantly altered in SSOH in the superior sectors. The area under the curve (AUC) for the receiver operating characteristic was 0.932 for the rim area, 0.926 for the cup-to-disc area ratio, and 0.882 for the cup shape measure. Among the HRT parameters, the largest AUC (0.988) was found for the cup shape measure in the nasal superior segment. The proportion classified as outside normal limits by the FSM discriminant function was 92.3% (12 eyes). For GPS, six eyes (46.2%) were classified as outside normal limits. For MRA, when borderline cases were considered test-negative or test-positive, 10 eyes (76.9%) or 11 eyes (84.6%) were classified as outside normal limits, respectively. The AUCs were 0.976 for the FSM discriminant function, 0.914 for the MRA overall classification, and 0.710 for the GPS overall classification.ConclusionsIn eyes with SSOH, there is a significant thinning of the rim, especially in the nasal superior sector. Approximately half of the eyes with SSOH were classified as abnormal using indices developed for detecting glaucoma, but the sectorial analysis revealed that the affected sectors were different from those of glaucoma. Optic nerve head measurements using the HRT may be useful in evaluating the optic disc characteristics in eyes with SSOH.

Effect of systemic moxaverine on ocular blood flow in humans

A number of common eye diseases are associated with ocular perfusion abnormalities. The present study aimed to investigate whether systemically administered moxaverine improves ocular blood flow. Sixteen healthy volunteers were studied in this randomized, double-masked, placebo-controlled, two-way crossover study. Moxaverine in a dose of 150 mg was administered i.v. Ocular haemodynamic parameters were measured before and after drug administration. Retinal arterial and venous diameters were measured with a retinal vessel analyser. Retinal blood velocity was assessed using laser Doppler velocimetry and choroidal and optic nerve head blood flow was measured with laser Doppler flowmetry. Moxaverine increased choroidal blood flow (22.6 ± 27.9%), an effect which was significant versus placebo (p = 0.015). Red blood cell velocity in retinal veins tended to increase by 13.6 ± 13.3% after infusion of moxaverine, but this effect was not significant compared with placebo (p = 0.25). In the optic nerve head moxaverine also tended to increase blood flow (11.8 ± 12.7%), but, again, this effect was not significant versus placebo (p = 0.12). Neither moxaverine nor placebo had an effect on retinal arterial diameters. In retinal veins moxaverine tended to induce vasodilation (2.6 ± 2.8%) and to increase blood flow (19.6 ± 16.5%), but these effects were not significant (both p = 0.12). The present study indicates an increase in choroidal blood flow after systemic infusion of a single dose of moxaverine in healthy subjects. Further studies are warranted to investigate whether these effects are also seen after longterm treatment in patients with ocular vascular disease.

The retinal nerve fiber layer and the optic nerve head morphology after glaucoma surgery

Abstract Purpose To detect and quantify changes in the retinal nerve fiber layer (RNFL) and the optic nerve head (ONH) morphology after glaucoma surgery. Methods 13 eyes of 13 patients with open‐angle glaucoma in which goniotrephining with scleral flap without intraoperative antimetabolites for progressive glaucoma damage was done were included in this prospective study. Before and 6 months after the surgery: the intraocular pressure (IOP) was measured, the thicknes of the RNFL was measured with a scanning laser polarimeter (GDx VCC), the confocal scanning laser ophthalmoscopy measurements of ONH with Heidelberg retina tomograph (HRT 3) were performed and the visual field was tested with Humphrey Field Analyser. Results The mean IOP before surgery was 24.5 ? 2.3 mmHg decreasing 6 months after to a mean of 13.9 ? 3.0 mmHg (p&lt;0.05). The RNFL measurements with GDx VCC revealed no differences between the mean TSNIT Avarage (p=0.383), mean Superior Avarage (p=0.756) and mean Inferior Avarage (p=0.269) before and after surgery. The ONH measurements with HRT 3 revealed postoperatively a significant increase in the mean Rim Area, Rim Volume and Cup Shape Measure, whereas Cup Area, Cup Volume and Linear Cup/Disc Ratio decreased (p&lt;0.05). There were no differences between the mean Height Variation Contour (p=0.678) and Mean RNFL Thickness (p=0.064) before and after surgery. Preoperatively the mean value of the Mean Deviation on automated perimetry was –18.82 ? 8.5 dB improving 6 months postoperatively to a mean of –16.63 ? 7.9 dB (p&lt;0.05). Conclusion Our study demonstrated the beneficial effect of IOP reduction obtained with glaucoma surgery on visual field indices and ONH parameters evaluated by HRT 3.

Diagnostic accuracy of Heidelberg Retina Tomograph III classifications in a Turkish primary open-angle glaucoma population

This study aimed to evaluate the diagnostic accuracy of Moorfields regression analysis (MRA) and the glaucoma probability score (GPS) in primary open-angle glaucoma (POAG) and to measure the level of agreement between the two algorithms in classifying eyes as normal or abnormal in a Turkish population. We prospectively selected 184 healthy subjects and 158 subjects with POAG, who underwent an ophthalmological examination, visual field analysis and imaging with the Heidelberg Retina Tomograph II, using HRT III software, Version 3.0. The diagnostic accuracies of the two classifications were measured when the borderline was taken as either normal (highest specificity criteria) or abnormal (highest sensitivity criteria). The agreement between them was calculated using the unweighted kappa (kappa) coefficient. Optic nerve head topographic parameters showed statistically significant differences between the control and POAG groups (p < 0.001). The parameters with the highest area under the receiver operating characteristic curves were global GPS (0.86), cup : disc area (0.85), rim : disc area (0.85) and vertical cup : disc (0.85). According to the highest specificity criteria, MRA had a sensitivity of 67.7% and a specificity of 95.1%, whereas the GPS had a sensitivity of 70.9% and a specificity of 88.0%. According to the highest sensitivity criteria, MRA had a sensitivity of 81.0% and a specificity of 75.0%, whereas the GPS had a sensitivity of 89.2% and a specificity of 57.6%. A moderate agreement of 68% (233 eyes) with a kappa coefficient of 0.51 was found between MRA and the GPS. The GPS automated classification showed similar sensitivity to MRA, but considerably lower specificity, when applied in a Turkish population.

Discriminating ability of optical coherence tomography data in staging glaucomatous damage

Objective: To evaluate the ability of retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) measurements, as determined by optical coherence tomography (OCT), to discriminate between normal eyesight and glaucoma and also among the different stages of glaucoma. Design: Observational cross-sectional study. Participants: Eighty-one controls and 213 glaucoma patients were enrolled in the study. Methods: The discriminating powers of OCT parameters for the detection of glaucoma and subgroups were compared by the area under the receiver operating characteristic (AUROC) curves. Results: The best RNFL thickness parameters for discriminating between early glaucoma and control eyes were inferior (0.74 [SE 0.04] μm), average (0.74 [SD 0.03] μm), and superior (0.68 [SD 0.03] μm). Among the ONH parameters, the best AUROC curve values were cup area (0.83 [SD 0.33]), cup/disc (C/D) area ratio (0.82 [SD 0.03]), and vertical integrated rim area (VIRA) (0.82 [SD 0.03]). The best AUROC values belonged to the RNFL thickness and were inferior (0.80 [SD 0.03]), superior (0.79 [SD 0.03]), and 6 o’clock (0.78 [SD 0.03]). The highest AUROC values were horizontal integrated rim width (HIRW) (0.74 [SD 0.04]), VIRA (0.64 [SD 0.04]), and rim area (0.63 [SD 0.04]) among the ONH parameters for early versus moderate glaucoma. The best AUROC values were inferior (0.81 [SD 0.03]), 6 o’clock (0.79 [SD 0.03]), and superior (0.78 [SD 0.04]) among the RNFL, and the best AUROC values were cup area (0.81 [SD 0.03]),VIRA (0.81 [SD 0.03]), and C/D area ratio (0.80 [SD 0.03]) among the ONH parameters, for moderate versus advanced glaucoma. Conclusions: RNFL and ONH OCT parameters might provide information for determining glaucomatous damage.

Effects of Age on Optical Coherence Tomography Measurements of Healthy Retinal Nerve Fiber Layer, Macula, and Optic Nerve Head

To determine the effects of age on global and sectoral peripapillary retinal nerve fiber layer (RNFL), macular thicknesses, and optic nerve head (ONH) parameters in healthy subjects using optical coherence tomography (OCT). Retrospective, cross-sectional observational study. A total of 226 eyes from 124 healthy subjects were included. Healthy subjects were scanned using the Fast RNFL, Fast Macula, and Fast ONH scan patterns on a Stratus OCT (Carl Zeiss Meditec, Dublin, CA). All global and sectoral RNFL and macular parameters and global ONH parameters were modeled in terms of age using linear mixed effects models. Normalized slopes were also calculated by dividing the slopes by the mean value of the OCT parameter for interparameter comparison. Slope of each OCT parameter across age. All global and sectoral RNFL thickness parameters statistically significantly decreased with increasing age, except for the temporal quadrant and clock hours 8 to 10, which were not statistically different from a slope of zero. Highest absolute slopes were in the inferior and superior quadrant RNFL and clock hour 1 (superior nasal). Normalized slopes showed a similar rate in all sectors except for the temporal clock hours (8-10). All macular thickness parameters statistically significantly decreased with increasing age, except for the central fovea sector, which had a slight positive slope that was not statistically significant. The nasal outer sector had the greatest absolute slope. Normalized macular slope in the outer ring was similar to the normalized slopes in the RNFL. Normalized inner ring had shallower slope than the outer ring with a similar rate in all quadrants. Disc area remained nearly constant across the ages, but cup area increased and rim area decreased with age, both of which were statistically significant. Global and regional changes caused by the effects of age on RNFL, macula, and ONH OCT measurements should be considered when assessing eyes over time. Proprietary or commercial disclosure may be found after the references.

Optic disc and retinal nerve fiber layer analysis in perimetrically unaffected eyes of glaucoma patients: an optical coherence tomography study

Abstract Purpose To evaluate whether optical coherence tomography (StratusOCT) may detect early changes in perimetrically unaffected (PU) fellow eyes of glaucomatous patients by analysis of retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH). Methods 37 glaucomatous patients with unilateral field loss and 34 age‐matched controls were recruited. In glaucoma patients, PU eyes and the affected ones were analyzed separately. For each group, mean values (±SD) of age, mean deviation, pattern standard deviation, as well as RNFL thickness parameters and ONH measurements were calculated. Comparisons between fellow eyes of glaucoma patients and between healthy and PU eyes of glaucoma patients conducted with t test and Mann‐Whitney U‐test, respectively. Number of clock‐hour sectors flagged with probability levels &lt;5% or &lt;1% were collected and differences between healthy subjects and PU eyes of glaucoma patients evaluated on Fisher exact test. Results Global (Average Thickness) and sectoral parameters (Inferior and Nasal Average), Max‐min, as well as 2‐ and 6‐o’clock sectors resulted significantly thinner in PU eyes than in control group, whereas ONH analysis did not provide any significant difference between the two groups. Proportion of eyes with clock‐hour position flagged with probability &lt;5% or &lt;1% was not significantly different between healthy and PU eyes. Conclusion PU eyes of glaucoma patients represent a group at risk to develop functional impairment over time since an early RNFL thinning was identified on OCT.

Interobserver variability in confocal optic nerve analysis (HRT)

To study the observer-related variability of optic nerve head (ONH) measurements using confocal laser scanning tomography (HRT I) in a screening setting. Six experienced glaucoma specialists independently evaluated 50 ONH topographies from 25 adults using HRT software ver. 2.01 in a masked fashion. ONH topographies were obtained from a cohort study of 882 healthy adults and additionally included one patient with glaucomatous eyes. A glaucoma-screening-like setting was intended. The mean interobserver difference was defined as the mean percentual difference between an observer's analysis and the mean of all six observers for all eyes and all observers. The interobserver range was calculated for each eye as the percentual difference between the lowest and highest measurement, with the highest measurement as denominator. Additionally, Kendall's coefficient of rank concordance was assessed for the main HRT parameters. Mean disc area ranged from 1.83 +/- 0.49 to 2.21 +/- 0.40 mm(2) (mean interobserver difference: 8.3%; interobserver range: 5-50%; rank concordance: 0.86). The lowest mean interobserver differences were found for mean retinal nerve fibre layer thickness (RNFLT; 6.5%), maximum cup depth (2.9%) and cup shape (6.8%). An increased interobserver range was significantly correlated to a low cup to disc area ratio (r=0.64, P<0.0001). The observer-dependent diagnostic variability of HRT measurements can lead to divergent diagnostic evaluation of the ONH in a screening setting. Any HRT software relying on a reference database is exposed to relevant observer-related variability of the disc area. For screening purposes, HRT measurements should be completed by other diagnostic methods to compensate for possible diagnostic uncertainty.

Comparison of optic nerve head topography in healthy adults using a Heidelberg retina tomograph and retinal thickness analyzer

To compare optic nerve head topographies measured using a Heidelberg retina tomograph I (HRT) and a retinal thickness analyzer (RTA) and thereby to determine clinical agreement between the two devices. Also, to investigate the reproducibility of optic nerve head measurements using the HRT and RTA. The study included 50 normal left eyes of 50 white adults. Ophthalmologic examination, keratometry, fundus photography, and examination with HRT and RTA were performed. To determine reproducibility, 10 volunteers had repeated examinations after a week. Mean (SD), median, and 5th and 95th percentiles were calculated for the HRT and RTA measurements and differences in measurements between HRT and RTA were tested for statistical significance. Clinical agreement was assessed with limits of agreement and reproducibility by a repeatability coefficient and intraclass correlation coefficient (ICC). Statistically significant differences (P < 0.05) between measurements by HRT and RTA were observed for all topographic parameters, except for rim area (P = 0.051) and height variation contour (P = 0.054). The limits of agreement between HRT and RTA were wide. The repeatability coefficient for HRT was good (< or =0.10) for all parameters, except for retinal nerve fibre layer (RNFL) cross-sectional area (0.28). The repeatability coefficient for RTA was >0.10 for cup area (0.15), rim area (0.19), maximum cup depth (0.13), height variation contour (0.11), and RNFL cross-sectional area (0.14). The ICC was good (> or =90%) for all parameters, except for mean RNFL thickness (89%) for HRT, and height variation contour (84%) for RTA. The observed differences within the limits of agreement were clinically important. Therefore, the two devices cannot be used interchangeably in clinical practice.

Correlation Between Retinal Nerve Fiber Layer Thickness and Central Corneal Thickness in Patients With Ocular Hypertension: An Optical Coherence Tomography Study

To correlate the retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters measured by optical coherence tomography (OCT) with central corneal thickness (CCT) measurements in patients with ocular hypertension (OHT). Observational cross-sectional study. setting: Tertiary care referral teaching institute. study population: Fifty-one eyes of 51 patients with OHT and 35 eyes of 35 normal subjects. Both groups were stratified into thin (CCT < or =555 microm) and thick (CCT >555 microm) cornea subsets. Ocular hypertensives were further stratified by CCT into < or =555 microm, 556 to 588 microm, and >588 microm subsets. observation procedure: RNFL thickness (average, superior average, and inferior average) and ONH parameters were measured by OCT. CCT was measured by ultrasonic pachymetry. main outcome measures: Correlation between CCT and OCT measurements of RNFL and ONH parameters. In the OHT group, CCT correlated significantly with all three RNFL measurements (Pearson's coefficient r = 0.412, 0.484, and 0.380, respectively) but with only four ONH parameters (cup-to-disk area ratio, cup area, rim area, and horizontally integrated rim width; r = -0.459, -0.283, 0.421, and 0.436, respectively). The RNFL in ocular hypertensives with CCT < or =555 microm was significantly thinner than in those with thick corneas (analysis of variance, post hoc Bonferroni comparisons, P < .001). RNFL thickness of normal subjects and ocular hypertensives with CCT >555 microm were similar. Ocular hypertensives with CCT < or =555 microm may represent patients who have either very early undetected glaucoma or an inherent structural predisposition to glaucomatous damage. This may in part explain the higher risk of these patients for progression to glaucoma.

Reproducibility of Optic Nerve Head Measurements Obtained by Optical Coherence Tomography

To evaluate reproducibility of optic nerve head (ONH) morphometry measurements obtained by optical coherence tomography (the fast optical disk protocol of the -Zeiss model 3000 OCT system) in normal and glaucomatous eyes. Prospective instrument-evaluation study. ONH measurements for 20 eyes were obtained in eight scan sessions taken during two visits to an ophthalmology clinic (10 normal patients, 10 glaucoma patients, one eye per subject). At every one of the eight sessions for each eye, estimates of eight ONH morphometry variables (see Main outcome measures) were obtained. The first two sessions were performed by two operators, followed by a 30-minute break. The same operators then completed a third and fourth session. This sequence was duplicated on a second visit. Intrasession, intersession, intervisit, and interoperator reproducibility of the eight variables were calculated by the use of a components variance model. Intraclass correlation coefficients (ICC) were used to assess reliability. Vertical integrated rim area, horizontal integrated rim area, disk area, cup area, rim area, cup/disk area ratio, cup/disk horizontal ratio, cup/disk vertical ratio. With the exception of the horizontal integrated rim area and rim area in normal subjects, the factor subject was the most important source of variance for all variables. Reliability values as measured by ICC for normal eyes were above 81%, with the exception of measurements of the horizontal integrated rim area (23.1%), rim area (33.3%), and disk area (64.7%). For glaucomatous eyes all values were above 85%, with the exception of the disk area (68.1%). ONH measurements obtained using the fast optical disk protocol of the Zeiss 3000 OCT system show good reproducibility, for both normal and glaucomatous eyes.

Analysis of Retinal Nerve Fiber Layer and Optic Nerve Head in Glaucoma with Different Reference Plane Offsets, Using Optical Coherence Tomography

To evaluate the performance of retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters analyzed with different offsets of reference plane in detecting early glaucomatous changes and in correlation with visual function using optical coherence tomography (OCT). This was a cross-sectional study consisting of 41 normal subjects and 30 with early and 40 with advanced glaucoma. RNFL thickness and ONH parameters were measured with reference planes positioned at 95, 150, and 205 microm above the level of retinal pigment epithelium (RPE). Discriminating power for early glaucoma detection and correlation with visual field MD for each parameter at different levels of reference plane were compared by using the analyses of area under the receiver operating characteristic curves (AUCs) and linear regression, respectively. All ONH measurements were significantly different between normal and glaucoma groups, irrespective of the level of reference plane. In normal eyes, changing the reference plane position resulted in significant differences in ONH measurements. Among all the parameters examined, integrated rim volume and RNFL thickness measured at 150 microm above the RPE showed the largest AUC (0.966) for early glaucoma detection, and the strongest correlation with visual function (r = 0.793), respectively. OCT analysis of the ONH and RNFL is useful for early glaucoma detection. Among the three reference planes examined in this study, measurements analyzed at 150 microm above the RPE demonstrated the best performance for glaucoma detection and correlation with visual function. Compared with ONH measurements, RNFL thickness may be a better indicator, reflecting retinal ganglion cell function and monitoring disease progression.

Les lasers diagnostiques dans le glaucome : la polarimétrie à balayage laser (GDx VCC) et la tomographie confocale par balayage laser (HRT)

Automated structural measurements of retinal nerve fibers and optic nerve head are possible with new lasers providing objective and reproductible data for analysis. Scanning laser polarimetry (GDx VCC), based on retardation of polarized light, assesses peripapillary nerve fiber layer thickness. Confocal scanning laser tomography yields precise topographic maps of the optic disc and peripapillary retina. The advantages, applications for glaucoma detection, both in a screening setting as well as for monitoring progression, limitations and pitfalls need to be well known and results should be analyzed with clinical data.

Evaluation of optic nerve head and peripapillary retinal blood flow in glaucoma patients, ocular hypertensives, and normal subjects

Purpose To compare optic nerve head (ONH) and peripapillary retinal blood flow in subjects with open-angle glaucoma (OAG), ocular hypertension (OHT), and normal eyes (NOR) using full-field perfusion analysis of scanning laser Doppler flowmetry (SLDF) images. Design Prospective, nonrandomized clinical trial. Methods Twenty uncontrolled OAG patients, 20 uncontrolled OHT patients, and 20 normal volunteers were prospectively enrolled. Mean ONH and peripapillary retinal blood flow measurements were performed by SLDF version 3.3 using five Heidelberg Retina Flowmeter (Heidelberg Engineering, Heidelberg, Germany) images. Statistical evaluations were performed on the three study groups using one-way analysis of variance. Flow values of the neuroretinal rim of the ONH, nasal peripapillary retina, and temporal peripapillary retina were then correlated with the clinical parameters of age, cup/disk (C/D) ratio, intraocular pressure (IOP), visual field mean defect, maximum-recorded IOP, and ocular perfusion pressure. Results Neuroretinal rim blood flow in the OAG group was 158 ± 79 arbitrary units (au), whereas in the OHT group it was 277 ± 158 au, and in the NOR group it was 272 ± 93 au. Differences were statistically significant between the OAG group and each of the other groups ( P = .001) but not between OHT and NOR groups ( P = .91). Peripapillary retinal flow values showed no statistically significant differences between groups ( P = .76 nasal and 0.93 temporal). Neuroretinal rim flow values showed a significant inverse correlation with C/D ratio ( P = .001). Mean neuroretinal rim blood flow was significantly higher (350 ± 184 au) in the 10 OHT patients with C/D ratios < 0.4 when compared with the 10 OHT patients with larger C/D ratios (203 ± 79 au) ( P = .039). Conversely, peripapillary retinal blood flow showed no significant correlation with any clinical parameter. Conclusion Open-angle glaucoma patients had significantly lower blood flow in the ONH compared with OHT patients and normal volunteers. No significant differences in ONH blood flow were found between ocular hypertensives and normal volunteers. For peripapillary retinal blood flow, no significant difference was seen between any groups. Neuroretinal rim blood flow was significantly inversely correlated to increased C/D ratio. Ocular hypertensives with larger C/D ratios demonstrated significantly lower rim blood flow compared with those with smaller C/D ratios, suggesting that rim perfusion might be reduced in high-risk ocular hypertensives before the manifestation of visual field defects.

Comparison of optic nerve head assessment with a digital stereoscopic camera (discam), scanning laser ophthalmoscopy, and stereophotography

Purpose To compare computer-assisted planimetry using the Discam system (Marcher Enterprises Ltd., Hereford, UK), confocal scanning laser ophthalmoscopy (CSLO), and stereoscopic disc photography with respect to optic nerve head (ONH) measurements and glaucoma status. Design Comparative, observational case series and interobserver variability study. Methods Three hundred eighty-six eyes of 233 consecutive subjects were imaged with the Discam, and a subset underwent ONH evaluation with CSLO (n = 297), stereoscopic photography (n = 233), or both. Subjects were classified into normal, glaucoma suspect, and glaucoma groups based on clinical findings of slit-lamp disc examination and visual field testing. Agreement of cup-to-disc ratio measurements among the three technologies was assessed by the intraclass correlation coefficient (ICC) and areas under the receiver operator characteristic (AROC) curves. Main outcome measures Cup-to-disc ratio as measured by Discam, CSLO, and stereography. Results Intraclass correlation coefficients calculated using the two-way random effects model for comparing Discam, CSLO, and stereography among cup-to-disc area ratio, vertical cup-to-disc ratio, and horizontal cup-to-disc ratio were 0.46 to 0.53. The ICC was higher for eyes with larger optic discs (0.51) than those with smaller ones (0.32). The ICC calculated using the fixed effects model for the Discam and CSLO comparison was 0.72. Areas under the receiver operator characteristic curves were 0.67 to 0.80 among the three technologies comparing normal with glaucomatous eyes. In general, there was no statistically significant difference between techniques with respect to sensitivity and specificity of glaucoma detection. Conclusions There is good agreement between ONH measurements obtained by Discam, CSLO, and stereography; however, the results are not interchangeable. Similar AROC curve values among all three techniques imply that the Discam, CSLO, and stereography perform equally for the determination of glaucoma status.

Correlation analysis of visual field thresholds and scanning laser ophthalmoscopic optic nerve head measurements in glaucoma.

In a cross-sectional study of 50 consecutive primary open-angle glaucoma cases, full threshold 30-2 visual fields on Humphrey Visual Field Analyser were correlated to stereometric parameters obtained using a scanning laser ophthalmoscope (HRT II). The strength of linear correlation between the stereometric parameters and visual thresholds was used to generate a correspondence map between the optic disc and the visual field. Rim/disc area ratio and cup/disc area ratio correlated with the visual thresholds at the highest number of points in the visual fields. Thresholds at superior hemifield locations correlated best with the rim/disc area ratio and cup/disc area ratio in the inferonasal sector and the ones in the inferior hemifield correlated best with the rim/disc area ratio and cup/disc area ratio in the superotemporal sector. Optic disc parameters correlated better with inferior field locations and non-edge points than superior field locations and edge points. The data indicate that rim/disc area ratio and cup/disc area ratio measurements on HRT II have a good correlation with visual field damage seen on automated visual fields.

Comparison of optic nerve head measurements obtained by optical coherence tomography and confocal scanning laser ophthalmoscopy

Purpose To evaluate the relationship between optic nerve head (ONH) measurements generated by optical coherence tomography (OCT; versions 2 and 3) and confocal scanning laser ophthalmoscopy (CSLO) and to compare the association between OCT and CSLO ONH measurements with glaucoma disease status, as determined by clinical evaluation and perimetry. Design Cross-sectional study. Methods In a prospective study in the glaucoma service of an academic department of ophthalmology, 159 eyes (97 subjects) and 77 eyes (44 subjects) were recruited in two separate periods. All subjects were scanned with a CSLO device. Subjects tested within the first period of recruitment were scanned with OCT version 2 and in the second period with OCT version 3. The main outcome measure was the correlation between automatic and manually defined OCT ONH measurements and the correlation of CSLO and OCT ONH measurements between devices and with glaucoma disease status. Results A high correlation was found between ONH measurements obtained by the automatic determination of ONH margin and those obtained by manual tracing of the disk margin ( r = .93 to .98). Optical coherence tomography and CSLO ONH measurements were highly correlated. Optical coherence tomography-measured mean disk area was significantly larger than that measured by CSLO, as were all other disk size-related parameters. The areas under the receiver operator characteristic (AROC) curves for the associations between CSLO and OCT ONH measurements and clinical diagnosis were found to be similar and in the range of 0.47 to 0.79 for both devices. Conclusions Automated OCT ONH measurements correlate highly with those obtained by manual tracing of disk margin. Optical coherence tomography and CSLO ONH analyses are highly correlated and have similar associations with glaucoma disease status.

Reproducibility of topographic measurements of the optic nerve head with the Heidelberg Retina Tomograph using separate and imported contour lines

Purpose: To investigate whether topographical measurements of the optic nerve head are more reproducible when the contour line is redrawn for each image as opposed to imported using the Heidelberg Retina Tomograph (HRT). Introduction: Optic nerve head topography can be measured in vivo using Confocal Scanning Laser Ophthalmoscopes such as the HRT. Image analysis requires that the area of the optic disc is defined by subjectively drawing a contour line around Elschnig's ring. The HRT software can export this contour line between images for a subject, or the contour line can be redrawn. Method: Ten eyes of ten normal volunteers (40–60 years) were analysed with the HRT. Seven 10° images of the optic disc were taken by one observer for each randomly selected eye. Focus and scan depth settings were kept constant. All available stereometric parameters were analysed using three methods: (1) with a separately drawn contour line for each individual image, (2) with a contour line imported from the first image into subsequent images of the series, (3) by repeatedly redrawing the contour line for a single image from each eye. All contour lines were drawn by one observer. Mean co-efficients of variation were calculated for each parameter for the three methods. Results: The mean co-efficient of variation for the parameters ranged from 1.7–23.4% (method 1), 0–20% (method 2) and 1.6–13.4% (method 3). Conclusion: These results show that redrawn contour lines increase variability. Topographical measurements of the optic nerve head are more reproducible if the contour line is imported across subsequent images rather than redrawn for each individual image.