Diagnostic ability of a linear discriminant function for optic nerve head parameters measured with optical coherence tomography for perimetric glaucoma

Comparison of Optical Coherence Tomography Structural Parameters for Diagnosis of Glaucoma in High Myopia

Importance

Diagnosis of glaucoma in highly myopic eyes is challenging. This study compared the glaucoma detection utility of various optical coherence tomography (OCT) parameters for high myopia.

Objective

To compare the diagnostic accuracy of single OCT parameters, the University of North Carolina (UNC) OCT Index, and the temporal raphe sign for discrimination of glaucoma in patients with high myopia.

Design, Setting, and Participants

This was a retrospective cross-sectional study conducted from January 1, 2014, and January 1, 2022. Participants with high myopia (axial length ≥26.0 mm or spherical equivalent ≤-6 diopters) plus glaucoma and participants with high myopia without glaucoma were recruited from a single tertiary hospital in South Korea.

Exposures

Macular ganglion cell-inner plexiform layer (GCIPL) thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters were measured in each participant. The UNC OCT scores and the temporal raphe sign were checked to compare diagnostic utility. Decision tree analysis with single OCT parameters, the UNC OCT Index, and the temporal raphe sign were also applied.

Main outcome and Measures

Area under the receiver operating characteristic curve (AUROC).

Results

A total of 132 individuals with high myopia and glaucoma (mean [SD] age, 50.0 [11.7] years; 78 male [59.1%]) along with 142 individuals with high myopia without glaucoma (mean [SD] age, 50.0 [11.3] years; 79 female [55.6%]) were included in the study. The AUROC of the UNC OCT Index was 0.891 (95% CI, 0.848-0.925). The AUROC of temporal raphe sign positivity was 0.922 (95% CI, 0.883-0.950). The best single OCT parameter was inferotemporal GCIPL thickness (AUROC, 0.951; 95% CI, 0.918-0.973), and its AUROC difference from the UNC OCT Index, temporal raphe sign, mean RNFL thickness, and ONH rim area was 0.060 (95% CI, 0.016-0.103; P = .007); 0.029 (95% CI, -0.009 to 0.068; P = .13), 0.022 (95% CI, -0.012-0.055; P = .21), and 0.075 (95% CI, 0.031-0.118; P < .001), respectively.

Conclusions and Relevance

Results of this cross-sectional study suggest that in discriminating glaucomatous eyes in patients with high myopia, inferotemporal GCIPL thickness yielded the highest AUROC value. The RNFL thickness and GCIPL thickness parameters may play a greater role in glaucoma diagnosis than the ONH parameters in high myopia.

Evaluation of University of North Carolina OCT Index for Diagnosis of Early Glaucoma

PURPOSE

To evaluate the diagnostic performance of the University of North Carolina (UNC) OCT Index based on Cirrus high-definition OCT to discriminate early glaucomatous eyes from normal eyes in clinical practice.

DESIGN

Evaluation of diagnostic test or technology.

PARTICIPANTS

Ninety-eight patients with early glaucoma and 98 age-matched normal subjects.

METHODS

Macular ganglion cell-inner plexiform layer (GCIPL) thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head parameters were measured in each subject. The measurements were run through the UNC OCT algorithm to compare their diagnostic abilities.

MAIN OUTCOME MEASURES

Area under the curve (AUC) of the receiver operating characteristic and sensitivity at 95% specificity.

RESULTS

The AUC of the UNC OCT Index was 0.974. The best AUCs of the single parameters were those of the minimum GCIPL (0.926) of the macular GCIPL, average RNFL (0.916) of the peripapillary RNFL, and rim area (0.964) of the optic nerve head. The AUC of the UNC OCT Index was significantly greater than those of the minimum GCIPL and average RNFL (all P values < 0.05), and also outperformed the rim area. The sensitivity value of the UNC OCT Index (90.8) was greater than that of single OCT parameters (minimum GCIPL, 42.9; average RNFL, 64.3; rim area, 84.7) at 95% specificity.

CONCLUSIONS

The diagnostic performance of the UNC OCT Index in discriminating early glaucomatous eyes from normal eyes is high and exceeds the best optic nerve head, peripapillary RNFL, and macular GCIPL parameters in clinical practice.

Early Glaucoma Discrimination Index

PURPOSE

To develop a new structural algorithm derived from optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness and asymmetry and validate it as a discriminate among normal, suspect, and early primary open-angle glaucoma (POAG).

STUDY DESIGN

A case-controlled observational clinical study.

MATERIALS AND METHODS

In total, 150 subjects (299 eyes) were selected, 61 normal, 46 suspect, and 43 early glaucoma, from Al-Azhar University Hospitals. They were in fifth decade and free from any ocular or systemic diseases affecting the retinal nerve fiber layer. They were investigated by two consecutive perimetry (1 month apart), and three scans of circumpapillary retinal nerve fiber layer (cpRNFL) by using Nidek spectral domain (SD)-OCT 3000 Lite. The cpRNFL thickness (cpRNFLT) and inter-eye asymmetry parameters were analyzed among the three groups. Then some selected parameters were selected and analyzed using a binary logistic regression analysis for developing the new algorithm. The new algorithm was tested for the best fitting, accuracy, and diagnostic ability among the three groups and was validated in the suspect group.

RESULTS

The new algorithm model [early glaucoma discrimination index (EGDI)] works well with only four variables; whole cpRNFLT, inferior quadrant cpRNFLT, inferotemporal clock hour (CH) cpRNFLT, and absolute inter-eye inferior quadrants asymmetry. The highest area under the curve (AUC) obtained from the EGDI among the three groups was 0.854. The validation analysis in the suspect group revealed a higher diagnostic ability in discrimination of early glaucoma with AUC of 0.989 (0.976-1.003).

CONCLUSION

The EGDI showed better diagnostic ability for diagnosis of glaucoma in the pre-perimetric stage. The new OCT algorithm is simple and can be run in any SD-OCT device without dependence on normative data.

HOW TO CITE THIS ARTICLE

Safwat H, Nassar E, Rashwan A. Early Glaucoma Discrimination Index. J Curr Glaucoma Pract 2020;14(1):16-24.

Validation of the UNC OCT Index for the Diagnosis of Early Glaucoma

Purpose

To independently validate the performance of the University of North Carolina Optical Coherence Tomography (UNC OCT) Index in diagnosing and predicting early glaucoma.

Methods

Data of 118 normal subjects (118 eyes) and 96 subjects (96 eyes) with early glaucoma defined as visual field mean deviation (MD) greater than -4 decibels (dB), aged 40 to 80 years, and who were enrolled in the Full-Threshold Testing Size III, V, VI comparison study were used in this study. CIRRUS OCT average and quadrants' retinal nerve fiber layer (RNFL); optic disc vertical cup-to-disc ratio (VCDR), cup-to-disc area ratio, and rim area; and average, minimum, and six sectoral ganglion cell-inner plexiform layer (GCIPL) measurements were run through the UNC OCT Index algorithm. Area under the receiver operating characteristic curve (AUC) and sensitivities at 95% and 99% specificity were calculated and compared between single parameters and the UNC OCT Index.

Results

Mean age was 60.1 ± 11.0 years for normal subjects and 66.5 ± 8.1 years for glaucoma patients (P < 0.001). MD was 0.29 ± 1.04 dB and -1.30 ± 1.35 dB in normal and glaucomatous eyes (P < 0.001), respectively. The AUC of the UNC OCT Index was 0.96. The best single metrics when compared to the UNC OCT Index were VCDR (0.93, P = 0.054), average RNFL (0.92, P = 0.014), and minimum GCIPL (0.91, P = 0.009). The sensitivities at 95% and 99% specificity were 85.4% and 76.0% (UNC OCT Index), 71.9% and 62.5% (VCDR, all P < 0.001), 64.6% and 53.1% (average RNFL, all P < 0.001), and 66.7% and 58.3% (minimum GCIPL, all P < 0.001), respectively.

Conclusions

The findings confirm that the UNC OCT Index may provide improved diagnostic perforce over that of single OCT parameters and may be a good tool for detection of early glaucoma.

Translational Relevance

The UNC OCT Index algorithm may be incorporated easily into routine clinical practice and be useful for detecting early glaucoma.

Diagnostic ability of Humphrey perimetry, Octopus perimetry, and optical coherence tomography for glaucomatous optic neuropathy

PurposeTo evaluate and compare the diagnostic accuracy of the Humphrey Field Analyzer (HFA), Octopus perimetry, and Cirrus OCT for glaucomatous optic neuropathy.MethodsEighty-eight healthy individuals and 150 open-angle glaucoma patients were consecutive and prospectively selected. Eligibility criteria for the glaucoma group were intraocular pressure ≥21 mm Hg and glaucomatous optic nerve head morphology. All subjects underwent a reliable standard automated perimetry with the HFA and Octopus perimeter, and were imaged with the Cirrus OCT. Receiver-operating characteristic (ROC) curves were plotted for the threshold values and main indices of the HFA and Octopus, the peripapillary retinal nerve fiber layer thicknesses, and the optic nerve head parameters. Sensitivities at 85 and 95% fixed-specificities were also calculated. The best areas under the ROC curves (AUCs) were compared using the DeLong method.ResultsIn the glaucoma group, mean deviation (MD) was -5.42±4.6 dB for HFA and 3.90±3.6 dB for Octopus. The MD of the HFA (0.966; P<0.001), mean sensitivity of the Octopus (0.941; P<0.001), and average cup-to-disc (C/D) ratio measured by the Cirrus OCT (0.958; P<0.001) had the largest AUCs for each test studied. There were no significant differences among them. Sensitivities at 95% fixed-specificity were 82% for pattern standard deviation of the HFA, 81.3% for average C/D ratio of OCT, and 80% for the MD of the Octopus.ConclusionsHFA, Octopus, and Cirrus OCT demonstrated similar diagnostic accuracies for glaucomatous optic neuropathy. Visual field and OCT provide supplementary information and thus these tests are not interchangeable.

Clinical Use of an Optical Coherence Tomography Linear Discriminant Function for Differentiating Glaucoma From Normal Eyes

PURPOSE

To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness obtained using high-definition optical coherence tomography (Cirrus HD-OCT) for discriminating between healthy controls and early glaucoma subjects.

METHODS

We prospectively selected 214 healthy controls and 152 glaucoma subjects (teaching set) and another independent sample of 86 healthy controls and 71 glaucoma subjects (validating set). Two scans, including 1 macular and 1 peripapillary RNFL scan, were obtained. After calculating the LDF in the teaching set using the binary logistic regression analysis, receiver operating characteristic curves were plotted and compared between the OCT-provided parameters and LDF in the validating set.

RESULTS

The proposed LDF was 16.529-(0.132×superior RNFL)-(0.064×inferior RNFL)+(0.039×12 o'clock RNFL)+(0.038×1 o'clock RNFL)+(0.084×superior GCIPL)-(0.144×minimum GCIPL). The highest area under the receiver operating characteristic (AUROC) curve was obtained for LDF in both sets (AUROC=0.95 and 0.96). In the validating set, the LDF showed significantly higher AUROC than the best RNFL (inferior RNFL=0.91) and GCIPL parameter (minimum GCIPL=0.88). The LDF yielded a sensitivity of 93.0% at a fixed specificity of 85.0%.

CONCLUSIONS

The LDF showed better diagnostic ability for differentiating between healthy and early glaucoma subjects than individual OCT parameters. A classification algorithm based on the LDF can be used in the OCT analysis for glaucoma diagnosis.

Discrimination of Glaucoma Patients From Healthy Individuals Using Combined Parameters From Spectral-domain Optical Coherence Tomography in an African American Population

PURPOSE

To create a multivariable predictive model for glaucoma in an exclusively African American population and to compare the performance of the model with individual structural parameters derived from SD-OCT.

PATIENTS AND METHODS

A total of 103 healthy eyes and 118 glaucomatous eyes of African American patients underwent SD-OCT optic disc and macular scanning. Twenty-seven optic nerve head, retinal nerve fiber layer (RNFL), and ganglion cell parameters were collected. A multivariable model was derived using a backward elimination variable selection procedure. Areas under the curve were used to measure the diagnostic performance of the individual parameters and the multivariable model.

RESULTS

The best performing parameters for glaucoma patients included inferior quadrant thickness (AUC=0.9239), average RNFL thickness (AUC=0.9209), sup2 RNFL thickness (AUC=0.9157), superior quadrant thickness (AUC=0.8906), and vertical CDR (AUC=0.8640). The best performing parameters for early glaucoma patients were sup2 RNFL thickness (AUC=0.8680), inferior quadrant thickness (AUC=0.8571), average RNFL thickness (AUC=0.8550), superior quadrant thickness (AUC=0.8420), and inf2 RNFL thickness (AUC=0.8420). The AUC of the multivariable model was 0.8918 for early glaucoma and 0.9744 for moderate/advanced glaucoma. There was some variability in the performance of the model based on disc size.

CONCLUSIONS

These findings confirm that several individual RNFL, ONH, and GCA parameters have excellent diagnostic performance in differentiating glaucomatous patients from healthy patients in African American population. A multivariable model was developed and validated with high diagnostic accuracy.

Structure-Function Relationship between Frequency-Doubling Technology Perimetry and Optical Coherence Tomography in Glaucoma

Purpose: To assess the relationship between the retinal nerve fibre layer (RNFL) thickness and the frequency-doubling technology perimetry (FDT) outcome. Methods: Sixty-two healthy individuals and 72 glaucoma patients were prospectively selected. All participants underwent a reliable FDT and optical coherence tomography (OCT). Pearson correlations were calculated between the unlogged threshold values of FDT and RNFL thicknesses measured by OCT. Results: Mild to moderate correlations were found between a few points from FDT and RNFL thicknesses in the vertical axis. The nasal superior area of FDT and the RNFL thickness at the 7-o'clock position had the strongest correlation (0.434, p < 0.001). Conclusions: The poor agreement between FDT and OCT parameters suggests that both instruments assess different characteristics of glaucomatous optic neuropathy. The map obtained validates previously reported clinical findings and contributes to a better understanding of the structure-function relationship in glaucoma. © 2014 S. Karger AG, Basel.

Retina measurements for diagnosis of Parkinson disease

PURPOSE

To test the diagnostic ability of spectral domain optical coherence tomography for the detection of Parkinson disease using retinal nerve fiber layer and retinal thickness parameters. Retinal pigment epithelium produces levodopa.

METHODS

Patients with Parkinson disease (n = 111) and healthy subjects (n = 200) were enrolled. The Spectralis optical coherence tomography was used to obtain retinal nerve fiber layer thickness and retinal measurements. Two linear discriminant functions (LDFs) were developed, one using retinal nerve fiber layer parameters and another using retinal thickness. A validating set was used to test the performance of both LDFs. Receiver operating characteristic curves were plotted and compared with the standard parameters provided by optical coherence tomography for both LDFs. Sensitivity and specificity were used to evaluate diagnostic performance.

RESULTS

The Retinal LDF combines only retinal thickness parameters and provided the best performance: 31.173 + 0.026 × temporal outer - 0.267 × superior outer + 0.159 × nasal outer - 0.197 × inferior outer - 0.060 × superior inner + 0.049 × foveal thickness. The largest areas under the receiver operating characteristic curve were 0.902 for Retinal LDF. The Retinal LDF yielded the highest sensitivity values.

CONCLUSION

Measurements of retinal thickness differentiate between subjects who are healthy and those with advanced Parkinson disease.

Assessment of the optic disc morphology using spectral-domain optical coherence tomography and scanning laser ophthalmoscopy

Objective. To compare the equivalent optic nerve head (OHN) parameters obtained with confocal scanning laser ophthalmoscopy (HRT3) and spectral-domain optical coherence tomography (OCT) in healthy and glaucoma patients. Methods. One hundred and eighty-two consecutive healthy subjects and 156 patients with open-angle glaucoma were divided into 2 groups according to intraocular pressure and visual field outcomes. All participants underwent imaging of the ONH with the HRT3 and the Cirrus OCT. The ONH parameters and the receiver operating characteristic (ROC) curves were compared between both groups. Results. Mean age did not differ between the normal and glaucoma groups (59.55 ± 9.7 years and 61.05 ± 9.4 years, resp.; P = 0.15). Rim area, average cup-to-disc (C/D) ratio, vertical C/D ratio, and cup volume were different between both instruments (P < 0.001). All equivalent ONH parameters, except disc area, were different between both groups (P < 0.001). The best areas under the ROC curve were observed for vertical C/D ratio (0.980 for OCT and 0.942 for HRT3; P = 0.11). Sensitivities at 95% fixed-specificities of OCT parameters were higher than those of HRT3. Conclusions. Equivalent ONH parameters of Cirrus OCT and HRT3 are different and cannot be used interchangeably. ONH parameters measured with OCT yielded a slightly better diagnostic performance.

Relationship between spectral-domain optical coherence tomography and standard automated perimetry in healthy and glaucoma patients

Objective. To evaluate the relationship between spectral-domain optical coherence tomography (OCT) and standard automated perimetry (SAP) in healthy and glaucoma individuals. Methods. The sample comprised 338 individuals divided into 2 groups according to intraocular pressure and visual field outcomes. All participants underwent a reliable SAP and imaging of the optic nerve head with the Cirrus OCT. Pearson correlations were calculated between threshold sensitivity values of SAP (converted to linear scale) and OCT parameters. Results. Mean age did not differ between the control and glaucoma groups (59.55 ± 9.7 years and 61.05 ± 9.4 years, resp.; P = 0.15). Significant differences were found for the threshold sensitivities at each of the 52 points evaluated with SAP (P < 0.001) and the peripapillary retinal nerve fiber layer (RNFL) thicknesses, except at 3 and 9 clock-hour positions between both groups. Mild to moderate correlations (ranging between 0.286 and 0.593; P < 0.001) were observed between SAP and most OCT parameters in the glaucoma group. The strongest correlations were found between the inferior RNFL thickness and the superior hemifield points. The healthy group showed lower and weaker correlations than the glaucoma group. Conclusions. Peripapillary RNFL thickness measured with Cirrus OCT showed mild to moderate correlations with SAP in glaucoma patients.

Short- and long-term phasing of intraocular pressure in stable and progressive glaucoma

AIMS

To evaluate short- (ST) and long-term (LT) intraocular pressure (IOP) in patients with stable (SG) and progressive glaucoma (PG).

MATERIALS AND METHODS

Fifty-two patients with treated glaucoma received a baseline 24-hour IOP curve and, every 6 months for 2 years, office-hour curve plus visual field test. Based on field changes, they were divided into 24 SG and 28 PG. ST and LT IOP mean, peak and fluctuation (standard deviation of measurements) were calculated. Parameters determining progression were evaluated by logistic regression.

RESULTS

At ST, SG and PG, respectively, had mean IOP of 16.8 ± 2.2 and 15.3 ± 1.8 mm Hg; peak of 19.7 ± 3.3, 17.4 ± 2.3 mm Hg; fluctuation of 2.3 ± 1.2, and 1.6 ± 0.6 mm Hg. LT parameters did not change in SG, whereas a significant increase of mean (+1.0 ± 1.5 mm Hg, p = 0.05), peak (2.0 ± 2.4 mm Hg, p = 0.0002), and fluctuation (0.5 ± 1.1 mm Hg, p = 0.008) occurred in PG. Mean, peak, and fluctuation were correlated, except mean and fluctuation in the long term. Association with progression was shown for change in mean IOP between ST and LT, and ST peak.

CONCLUSIONS

SG and PG may show different IOP parameters when intensively measured at baseline and follow-up. Mean IOP change between ST and LT periods and ST peak were the parameters associated with progression.

Comparison of automated analysis of Cirrus HD OCT spectral-domain optical coherence tomography with stereo photographs of the optic disc

OBJECTIVE

To evaluate a new automated analysis of optic disc images obtained by spectral-domain optical coherence tomography (SD OCT). Areas of the optic disc, cup, and neural rim in SD OCT images were compared with these areas from stereoscopic photographs to represent the current traditional optic nerve evaluation. The repeatability of measurements by each method was determined and compared.

DESIGN

Evaluation of diagnostic technology.

PARTICIPANTS

One hundred nineteen healthy eyes, 23 eyes with glaucoma, and 7 glaucoma suspect eyes.

METHODS

Optic disc and cup margins were traced from stereoscopic photographs by 3 individuals independently. Optic disc margins and rim widths were determined automatically in SD OCT. A subset of photographs was examined and traced a second time, and duplicate SD OCT images also were analyzed.

MAIN OUTCOME MEASURES

Agreement among photograph readers, between duplicate readings, and between SD OCT and photographs were quantified by the intraclass correlation coefficient (ICC), by the root mean square, and by the standard deviation of the differences.

RESULTS

Optic disc areas tended to be slightly larger when judged in photographs than by SD OCT, whereas cup areas were similar. Cup and optic disc areas showed good correlation (0.8) between the average photographic reading and SD OCT, but only fair correlation of rim areas (0.4). The SD OCT was highly reproducible (ICC, 0.96-0.99). Each reader also was consistent with himself on duplicate readings of 21 photographs (ICC, 0.80-0.88 for rim area and 0.95-0.98 for all other measurements), but reproducibility was not as good as SD OCT. Measurements derived from SD OCT did not differ from photographic readings more than the readings of photographs by different readers differed from each other.

CONCLUSIONS

Designation of the cup and optic disc boundaries by an automated analysis of SD OCT was within the range of variable designations by different readers from color stereoscopic photographs, but use of different landmarks typically made the designation of the optic disc size somewhat smaller in the automated analysis. There was better repeatability among measurements from SD OCT than from among readers of photographs. The repeatability of automated measurement of SD OCT images is promising for use both in diagnosis and in monitoring of progression.