Optic Nerve Head Topographic Parameters Research Articles

Value of disc topographic measurements for the discrimination of glaucoma suspects from early primary open angle glaucoma cases: A thin discriminative line

PurposeTo determine the diagnostic value of optic nerve head (ONH) topographic parameters measured by swept-source optical coherence tomography (SS-OCT) in differentiating between early glaucoma cases, glaucoma suspects (GSs), and healthy eyes. MethodsThe files of GSs, those with an early primary open angle glaucoma (POAG) diagnosis, and healthy eyes were retrospectively screened. Demographic characteristics, retinal nerve fibre measurements, visual field examinations, and ONH topographic parameters, including rim area, disc area, vertical and horizontal cup-to-disc ratios (CDRs), and cup volume, were compared between the groups. A receiver operating characteristic (ROC) curve analysis was performed on the ONH parameters. ResultsA total of 170 eyes from 85 GSs, 114 eyes from 57 patients with a diagnosis of early POAG, and 70 healthy eyes from 48 subjects were included in the study. The median age was 52.1 ± 0.9 years for the POAG group, 60.2 ± 1.1 years for the GS group, and 60.5 ± 1.6 for the controls. In the comparison of the ONH parameters between the groups, only rim area statistically significantly differed between the POAG and GS groups. However, all ONH parameters statistically significantly differed between the GS and control groups (p< 0.05). The mean rim areas of the GS, POAG, and control groups were 1.278 ± 0.055 mm2, 1.073 ± 0.065 mm2, and 1.446 ± 0.055 mm2, respectively, being statistically significantly higher in the controls and lower in the POAG group (p < 0.001). The highest area under the curve (AUC) value belonged to vertical CDR for the discrimination of the eyes with POAG from healthy eyes [0.806 (0.728–0.869, p < 0.001] and rim area for the discrimination of POAG cases and GSs [0.728 (0.650–0.797, p < 0.001]. ConclusionThere are significant differences in all ONH parameters between the eyes of GSs and healthy eyes. For the discrimination of early POAG and GS cases, topographic disc parameters may have value. In this study, rim area significantly differed between the GS and POAG groups, and it had the highest AUC value amongst the evaluated ONH parameters in the discrimination of early POAG cases S GSs.

Discrimination of glaucomatous from non-glaucomatous optic neuropathy with swept-source optical coherence tomography

To assess the ability of optic nerve head (ONH) parameters, peripapillary retinal nerve fiber layer (pRNFL), and macular ganglion cell layer (GCL) thickness measurements with swept-source optical coherence tomography (SS-OCT), to discriminate between glaucomatous and non-glaucomatous optic neuropathy (GON and NGON). This retrospective cross-sectional study involved 189 eyes of 189 patients, 133 with GON and 56 with NGON. The NGON group included ischemic optic neuropathy, previous optic neuritis, and compressive, toxic-nutritional, and traumatic optic neuropathy. Bivariate analyses of SS-OCT pRNFL and GCL thickness and ONH parameters were performed. Multivariable logistic regression analysis was employed to obtain predictor variables from OCT values, and the area under the receiver operating characteristic curve (AUROC) was calculated to differentiate between NGON and GON. Bivariate analyses showed that the overall and inferior quadrant of the pNRFL was thinner in the GON group (P=0.044 and P<0.01), while patients with NGON had thinner temporal quadrants (P=0.044). Significant differences between the GON and NGON groups were identified in almost all the ONH topographic parameters. Patients with NGON had thinner superior GCL (P=0.015), but there were no significant differences in GCL overall and inferior thickness. Multivariate logistic regression analysis demonstrated that vertical cup-to-disc ratio (CDR), cup volume, and superior GCL provided independent predictive value for differentiating GON from NGON. The predictive model of these variables along with disc area and age achieved an AUROC=0.944 (95% CI 0.898-0.991). SS-OCT is useful in discriminating GON from NGON. Vertical CDR, cup volume, and superior GCL thickness show the highest predictive value.

Structural assessment of the optic nerve in patients with obstructive sleep apnea syndrome: Case-control study.

Obstructive sleep apnea syndrome has been identified as a possible risk factor for optic nerve pathology such as glaucoma, nonarteritic ischemic optic neuropathy, and optic disk edema. Accordingly, we aimed to evaluate structural changes of the apparently normal optic nerve in obstructive sleep apnea syndrome patients with effects of its severity. In this prospective case-control study, 47 eyes of 47 obstructive sleep apnea syndrome patients diagnosed with polysomnography and 40 eyes of 40 healthy subjects were included. Spectral-domain optical coherence tomography was used to evaluate the peripapillary retinal nerve fiber layer thickness, optic nerve head topographic parameters, and retinal ganglion cell-inner plexiform layer thickness. The average peripapillary nerve fiber layer thickness was lower in obstructive sleep apnea syndrome patients than in controls (90.74±7.98 vs 94.93±6.13μm; p = 0.008). The average cup/disk ratio and the vertical cup/disk ratio in patients with OSAS were significantly higher compared to the controls (both p < 0.001). However, no significant difference in retinal ganglion cell-inner plexiform layer thickness was found. Even if the retinal ganglion cell-inner plexiform layer thicknesses did not significantly differ between the obstructive sleep apnea syndrome and control groups, obstructive sleep apnea syndrome patients showed a decreased peripapillary nerve fiber layer thickness and increased optic nerve head parameters. These findings can be used as an indicator of optic nerve damage in the early diagnosis of obstructive sleep apnea syndrome patients.

Branch retinal vein occlusion and optic nerve head topographic parameters: the Singapore Indian eye study

AimTo examine the association between branch retinal vein occlusion (BRVO) and quantitative optic disc topographic parameters.MethodsThe Singapore Indian Eye Study (SINDI) is a population-based study of 3400 Singapore Indians aged...

Comparison of Optic Disc Topography in the Cases With Graves Disease and Healthy Controls

To compare the optic nerve head topographic parameters of the cases with Graves disease (GD), and the age and sex-matched control group, by using Heidelberg retinal tomography III. We evaluated both eyes of 65 patients with GD and 54 age and sex-matched controls. For statistical analysis, Mann-Whitney U test and independent sample t test were used. Statistical significance was set as P < 0.05. The study group consisted of 22 male (33.8%) and 43 female (66.2%) GD cases with a mean age of 40.3 ± 11.9 years and the control group consisted of 26 male (48.1%) and 28 female (51.9%) healthy controls with a mean age of 36.9 ± 7.6 years. The differences between the age and sexes of the groups were not statistically significant (P = 0.07 and P = 0.11, respectively). The mean intraocular pressure of the study group was 14.6 ± 2.9 mm Hg (range, 8 to 20 mm Hg), whereas in the control group, it was 13.4 ± 2.1 mm Hg (range, 10 to 19 mm Hg). The difference between the intraocular pressures was statistically significant (P = 0.01). The mean retinal nerve fiber layer (RNFL) thickness (0.31 ± 0.08 mm) and the mean RNFL cross-sectional area (1.5 ± 0.43 mm) of the control group were greater than the mean RNFL thickness (0.25 ± 0.06 mm) and the mean RNFL cross-sectional area (1.30 ± 0.32 mm) of the study group (P = 0.02, P = 0.03 respectively). This result suggests that patients with GD may have thinner RNFL than healthy controls.

Association between corneal biomechanical properties and optic nerve head morphology in newly diagnosed glaucoma patients

To investigate the association between corneal biomechanics and optic nerve head morphology in newly diagnosed primary open-angle glaucoma patients. Hospital based prospective study. Forty-two untreated newly diagnosed primary open-angle glaucoma patients. Patients underwent corneal hysteresis measurement using the Ocular Response Analyzer and confocal scanning laser ophthalmoscopy for optic nerve head topography evaluation. One eye was selected randomly for analysis. Data collected included age, race, gender, intraocular pressure and central corneal thickness. Multiple regression analysis (controlling for baseline intraocular pressure and disc area) was used to investigate factors associated with the following optic nerve head topographic parameters: linear cup-to-disc ratio and mean cup depth. Mean age of participants was 66.7 ± 11.8 years. Corneal hysteresis was the only factor significantly associated with both mean cup depth (correlation coefficient [r] = -0.34, P = 0.03) and cup-to-disc ratio (r = -0.41, P = 0.01). Central corneal thickness was significantly associated with mean cup depth (r = -0.35, P = 0.02), but not with cup-to-disc ratio (r = -0.25, P = 0.13). Although a trend towards a positive association between age and cup-to-disc ratio was identified (r = 0.26, P = 0.08), age was not significantly associated with mean cup depth (r = 0.06, P = 0.72). When comparing fellow eyes of patients with bilateral glaucoma, the eye with higher corneal hysteresis had smaller cup-to-disc ratio in 75% of the cases. In untreated newly diagnosed primary open-angle glaucoma patients, those with thinner corneas and mainly lower corneal hysteresis values had a larger cup-to-disc ratio and deeper cup, independently of intraocular pressure values and disc size.

Topographic Differences between Large and Normal Optic Discs: A Confocal Scanning Laser Ophthalmoscopy Study

The aim of the study was to investigate the optic nerve head parameters of healthy macrodiscs to provide standard measurements for them to be the basis for future quantitative comparisons. Sixty-nine subjects with macrodisc (disc area larger than 2.82 mm(2)) and 91 healthy controls (disc area between 1.16 and 2.82 mm(2)) were recruited. After a complete ophthalmic examination, confocal scanning laser ophthalmoscopy was performed in all participants. The stereometric parameters of confocal scanning laser ophthalmoscopy examination and the proportion of subjects classified as normal, borderline, and glaucomatous by the Moorfield Regression Analysis were compared between groups. A total of 160 subjects were included in the study. The average disc sizes in the control and macrodisc groups were 2.14 ± 0.33 mm(2) and 3.36 ± 0.36 mm(2), respectively. Cup area (p<0.001), rim area (p=0.01), cup volume (p<0.001), cup/disc area ratio (p<0.001), linear cup/disc ratio (p<0.001), mean cup depth (p<0.001), maximum cup depth (p<0.001), and cup shape measure (p<0.001) differed significantly between the 2 groups. The parameters of the optic nerve head which did not differ significantly between groups were rim volume (p=0.17) and height variation contour (p=0.88). A significantly higher number of eyes were erroneously identified as abnormal (15.1% vs 79.4%) by Moorfield Regression Analysis in the macrodisc group (p<0.001). Rim volume and height variation contour were the only optic nerve head topographic parameters that were similar in eyes with large and normal disc sizes. They seem to be promising parameters in the evaluation and comparison of the optic nerve head of subjects with macrodisc.

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.

Correlación entre los índices globales de la perimetría automatizada convencional y los parámetros topográficos papilares (Heidelberg Retina Tomograph II)

To correlate the optic nerve head topographic parameters measured by the Heidelberg Retina Tomograph II (HRT) with the perimetric indices of standard automated perimetry (SAP). This study included 101 normal subjects, 247 ocular hypertensive eyes (increased intraocular pressure with normal SAP) and 102 glaucomatous subjects (IOP above 21 mm Hg and abnormal standard automated perimetry). Only one eye was randomly chosen from each subject for the study. The visual field was evaluated by means of Humphrey Field Analyzer (24-2 full threshold strategy). The HRT II (Heidelberg Engineering) was used to acquire and measure the optic disc topographic parameters. Pearson correlations between topographic data and perimetric indices were performed for the total sample and each group of patients. The distribution of values obtained in the samples was normal. A significant correlation was found between several optic disc parameters and the global indices of SAP. Rim area, rim volume, cup/disc area ratio, rim/disc area ratio, cup shape measurement, RNFL cross-sectional area, and discriminant functions FSM and RB, showed the strongest correlation with the visual field indices in the total and glaucoma groups (RIM AREA: total group: r=0.32; p=4.14x10(-11)/glaucoma group: r=0.28; p=0.004. RIM VOLUME: total group: r=0.26; p=1.55x10(-7)/glaucoma group: r=0.26; p=0.006). The ocular hypertensive group showed few significant correlations. The correlations found between standard automated perimetry and HRT defined topographic parameters allow a better understanding of glaucomatous damage and make decision-making easier.

Three-dimensional Retinal Imaging with High-Speed Ultrahigh-Resolution Optical Coherence Tomography

To demonstrate high-speed, ultrahigh-resolution, 3-dimensional optical coherence tomography (3D OCT) and new protocols for retinal imaging. Ultrahigh-resolution OCT using broadband light sources achieves axial image resolutions of approximately 2 microm compared with standard 10-microm-resolution OCT current commercial instruments. High-speed OCT using spectral/Fourier domain detection enables dramatic increases in imaging speeds. Three-dimensional OCT retinal imaging is performed in normal human subjects using high-speed ultrahigh-resolution OCT. Three-dimensional OCT data of the macula and optic disc are acquired using a dense raster scan pattern. New processing and display methods for generating virtual OCT fundus images; cross-sectional OCT images with arbitrary orientations; quantitative maps of retinal, nerve fiber layer, and other intraretinal layer thicknesses; and optic nerve head topographic parameters are demonstrated. Three-dimensional OCT imaging enables new imaging protocols that improve visualization and mapping of retinal microstructure. An OCT fundus image can be generated directly from the 3D OCT data, which enables precise and repeatable registration of cross-sectional OCT images and thickness maps with fundus features. Optical coherence tomography images with arbitrary orientations, such as circumpapillary scans, can be generated from 3D OCT data. Mapping of total retinal thickness and thicknesses of the nerve fiber layer, photoreceptor layer, and other intraretinal layers is demonstrated. Measurement of optic nerve head topography and disc parameters is also possible. Three-dimensional OCT enables measurements that are similar to those of standard instruments, including the StratusOCT, GDx, HRT, and RTA. Three-dimensional OCT imaging can be performed using high-speed ultrahigh-resolution OCT. Three-dimensional OCT provides comprehensive visualization and mapping of retinal microstructures. The high data acquisition speeds enable high-density data sets with large numbers of transverse positions on the retina, which reduces the possibility of missing focal pathologies. In addition to providing image information such as OCT cross-sectional images, OCT fundus images, and 3D rendering, quantitative measurement and mapping of intraretinal layer thickness and topographic features of the optic disc are possible. We hope that 3D OCT imaging may help to elucidate the structural changes associated with retinal disease as well as improve early diagnosis and monitoring of disease progression and response to treatment.

Laser Scanning Tomography of the Optic Nerve Head in a Normal Elderly Population: The Bridlington Eye Assessment Project

To assess optic nerve head topographic parameters using the Heidelberg Retina Tomograph (HRT) II (Heidelberg Engineering GmbH, Dossenheim, Germany) in a normal elderly population. Optic nerve head analysis of 918 eyes of 459 normal elderly patients was performed. All patients were consecutive in a cohort screened for eye disease. Normal subjects were defined with a normal visual field on automated suprathreshold screening, intraocular pressure less than 22 mmHg, and minimum corrected visual acuity of 6/12. All optic discs were contoured by two investigators and the mean parameters analyzed. The effects of age, sex, and disc size were assessed. Subjects' (262 women and 197 men) mean age was 72.6 +/- 5.1 (SD) years (range, 65.5-89.3). Mean +/- SD global disc area, cup/disc area ratio, and neuroretinal rim area were 1.98 +/- 0.36 mm2, 0.22 +/- 0.14, and 1.52 +/- 0.31 mm2, respectively. Disc area did not differ significantly based on eye side or sex. The women were found to have a significantly larger rim volume, mean retinal nerve fiber layer (RNFL) thickness, and cross-sectional area than the men and tended to have smaller cup areas/volumes and cup/disc area ratios. Most tomography parameters were found to be significantly influenced by disc size. To the authors' knowledge, this is the first large study of optic nerve head parameters in the elderly normal population using the HRT II. This age range is particularly relevant to glaucoma detection and pertinent to discriminant analyses separating normal subjects from glaucoma in screening for the disease. Given the systematic differences between the parameters in men and women, reference ranges should be quoted by sex.

Assessment of optic nerve head topographic parameters with a confocal scanning laser ophthalmoscope.

To assess the disc area, age, sex, laterality (side of the eyes) and refractive error dependent differences in optic nerve head topographic parameters in a normal population. Optic nerve head topographic analysis of both eyes of 551 healthy Turkish subjects aged 11-75 years (1102 eyes) was performed using a confocal scanning laser ophthalmoscope, the Heidelberg Retinal Tomograph II (HRT II). The effects of disc size, sex, laterality (side of the eyes), age and refractive error on optic nerve head topographic parameters were assessed. Subjects were divided into three different age groups (<30 years, 30-60 years, >60 years) and three different disc area groups (<2.00 mm(2), 2.00-2.25 mm(2), >2.25 mm(2)). Disc area, topography standard deviation and a total of 12 topographic parameters were calculated by HRT II for each subject. Statistical analysis was performed using Student's t-test, multiple regression analysis, Tukey-HSD test, anova and Pearson's correlation coefficient. A total of 543 subjects (298 women and 245 men) were included in the study. The mean disc area of the subjects was 2.12 +/- 0.47 mm(2) (range 1.16-4.98 mm(2)). The mean refractive error of the subjects was -0.58 +/- 1.71 D (range -4.75 D to +4.25 D). The mean cup shape measure was -0.21 +/- 0.07 (95% confidence interval -0.07 to -0.35). The disc area was significantly correlated with all of the topographic parameters but two; namely, the cup shape measure and the height variation contour. Significant age-related differences were detected in four parameters (mean retinal nerve fibre layer [RNFL] thickness, disc area, cup-to-disc area ratio, cup area) and significant sex-related differences were detected three parameters (mean RNFL thickness, height variation contour, RNFL cross-sectional area). However, there were no significant differences in any of the parameters for laterality and refractive error. The parameter cup shape measure did not correlate with any of the five variables investigated. Cup shape measure was the only optic nerve head topographic parameter that was independent of age, sex, disc area, laterality and the refractive error. It seems to be a promising parameter in evaluation and comparison of the optic discs of normal subjects, with different disc area, age, sex, refraction error and laterality, as being independent of the main variation factors of the disc topography.

Reproducibility of the Measurements of the Optic Nerve Head Topographic Variables with a Confocal Scanning Laser Ophthalmoscope

Purpose: To determine the optic nerve head topographic parameters with the least variability in repeat measurements. Methods: We randomly selected and evaluated 1 eye each of 20 healthy subjects, a total of 20 eyes. We used the confocal scanning laser ophthalmoscope (CSLO) for optic nerve head analysis. The disc area and a total of 13 parameters were determined by Top SS. Each subject was examined five times, each time on a different day, during a 2-month period. We obtained a series of five 10 × 10° images for each eye per visit. Three of the five images were randomly selected to create a mean image. Coefficients of variation of each of the 13 variables studied were calculated separately by using those five different optic nerve head topographic measurements. Results: The subjects were 11 women and 9 men. The mean age of the subjects was 30.5 ± 6.9. The mean optic disc areas were 2.26 ± 0.39 mm 2 and 1.96 ± 0.37 mm 2 for the men and the women, respectively ( P > .05). The mean coefficient of variation for measurement of the variables was found to range between 1.2% and 9.8%. The variables, cup shape, volume above, average depth, and volume below, were found to yield the best reproducible measurements. Conclusion: The CSLO with its highly reproducible measurements (<10% error) offers a highly objective, safe, and effective method for clinical use in measurements of the topography of the optic nerve head. The subtle differences in the variables, cup shape, volume above, average depth, and volume below, may be of vital importance in the follow-up of those diseases requiring longitudinal monitoring of the optic nerve head, namely ocular hypertension and glaucoma.

Application of Discriminant, Classification Tree and Neural Network Analysis to Differentiate between Potential Glaucoma Suspects with and without Visual Field Defects

Purpose: This study has two objectives. The first one is to investigate the question whether it is possible to discriminate between eyes with and without a glaucomateous visual field defect based on standard ophthalmologic examinations as well as optic nerve head topographic parameters. The second objective raises the question of the ability of several suggested statistical models to generalize their results to new, previously unseen patients.Methods: To investigate the above addressed question: (a) independent, two-sidedt-tests, (b) a linear discriminant analysis with a forward stepwise variable selection algorithm, (c) four classification tree analyses and (d) three different neural network models with a forward, backward and a genetic variable selection algorithm were applied to 1020 subjects with a normal visual field and 110 subjects with a glaucomateous visual field defect. The Humphrey Visual Field Analyzer was used to test the visual fields and the TopSS®Scanning Laser Tomograph measured the optic nerve topography. A 10-fold cross-validation method was used for the models (b), (c) and (d) to compute approximative 95% confidence intervals for the specificity and sensitivity rates.A literature study of 18 studies dealt with the question whether/how the generalization error was controlled (control of sample bias, cross-validation procedures, training net size for valid generalization). It was also looked up whether point estimators or 95% confidence intervals were used to report specificity and sensitivity rates.Results: (a) Only few differences of the means could be found between both groups, including age, existing eye diseases, best corrected visual acuity and visual field parameters. The linear discriminant analysis (b), the classification tree analyses (c) and the neural networks (d) ended up with high specificity rates, but low sensitivity rates.The literature study showed that three models did not apply a cross-validation procedure to report their results. Two models used a test sample cross-validation and thirteen used a v-fold cross-validation method. Although most authors reported confidence intervals for the area under the ROC, no author reported confidence intervals for the true, but unknown sensitivity and specificity rates.Conclusions: (a) The results of this study suggest that the combination of standard ophthalmologic eye parameters and optic nerve head topographic parameters of the TopSS®instrument are not sufficient to discriminate properly among normal eyes and eyes with a glaucomateous visual field defect. (b) We follow important suggestions given in statistical learning theory for proper generalization and suggest to apply these methods to the given models or to models in future. At least three conditions should be met: (1) confidence intervals instead of point estimators to assess the classification performance of a model (control of test sample bias); (2) sensitivity and specificity rates should be estimated instead of reporting a point estimator for the area under the ROC and (3) the generalization error should be reported both in a training and a test sample and methods should be applied to select an appropriate training sample size for valid generalization.

Correlation Between Blue Chromatic Macular Sensitivity and Optic Disc Change in Early Glaucoma Patients

To investigate the relationship between morphological changes of the optic nerve head (ONH) and macular sensitivity(MS) determined with blue-on-yellow(B on Y) and white on white (W on W) perimetry in normal subjects and patients with glaucoma. One randomly chosen eye was evaluated in each of 28 normal subjects, 23 patients with ocular hypertension(OH), and 23 patients with early primary open-angle glaucoma(POAG). Mean values for MS by B on Y and W on W perimetry were obtained with the macular program using a modified Humphrey Field Analyzer(HFA). The Heidelberg Retina Tomograph(HRT) with software version 2.01 was used to evaluate the topographic parameters of temporal sector in ONH. There was no significant difference in temporal topographic parameters of ONH among the three clinical groups. Mean values for MS of B on Y and W on W perimetry in early POAG were significantly lower than in normal subjects and OH. Mean values for MS of W on W perimetry showed no significant correlation with ONH parameters of the temporal sector. In early POAG, mean values for MS of B on Y perimetry significantly correlated with cup area, cup/disc area ratio, cup volume, and rim volume in the temporal sector of ONH. The measurement of mean MS of B on Y might be able to detect the glaucomatous optic nerve damage due to increased intraocular pressure prior to the morphological changes of ONH in early stages of glaucoma.