Effect of the Eye Tracking System on the Reproducibility of Measurements Obtained With Spectral-domain Optical Coherence Tomography in Glaucoma.

PURPOSE: The purpose of this study was to evaluate whether the eye tracking system (ETS) improved the reproducibility of a single circle peripapillary retinal nerve fiber layer (RNFL) measurement acquired with spectral-domain optical coherence tomography (OCT). MATERIALS AND METHODS: The sample comprised 205 individuals divided into 2 groups according to intraocular pressure and visual field outcomes. A total of 100 healthy individuals and 105 patients with open-angle glaucoma underwent imaging of the optic nerve head with OCT 3 times during the same session and 2 additional times in subsequent sessions (30 days apart). Intraclass correlation coefficient (ICC), coefficient of variation, and test-retest variability were calculated for the RNFL thickness acquired with and without the ETS enabled, and compared. RESULTS: The glaucoma group mainly comprised patients with moderate glaucoma (mean deviation of standard automated perimetry, -6.73±6.2 dB). The RNFL thicknesses did not differ between acquisitions with or without the ETS activated and disabled. All ICCs were >0.9 in the control and glaucoma groups with or without the ETS activated. The best parameter in the intersession analysis (with ETS activated) was global RNFL thickness (ICC, 0.95; coefficient of variation, 2.7%; and test-retest variability, 2.87 µm). The reproducibility and repeatability of RNFL measurements did not differ significantly between acquisitions with or without the ETS in either group. CONCLUSIONS: The reproducibility of peripapillary RNFL thicknesses acquired with OCT was excellent. The variability between OCT measurements did not decrease with the ETS activated.

Macular Retinal Ganglion Cell Layer Thickness Is Not Reduced in Patients with Obstructive Sleep Apnea.

PURPOSE: To evaluate macular ganglion cell layer (GCL) and ganglion cell-inner plexiform layer (GCIPL) thicknesses in patients with obstructive sleep apnea (OSA) syndrome. METHODS: 73 OSA patients and 67 age-matched controls were consecutively and prospectively enrolled. All participants underwent at least one reliable standard automated perimetry (SAP) and were imaged with spectral-domain optical coherence tomography (OCT) using two different devices. The OCT parameters were compared between groups, and Pearson correlations between main indices of SAP and OCT parameters were calculated. RESULTS: The pattern standard deviation of SAP was higher in the OSA group (p = 0.001). Mean GCIPL thickness was 82.99 ± 10.30 and 80.78 ± 12.15 µm in the control and OSA groups, respectively (p = 0.25), and GCL thickness was 44.93 ± 11.42 µm in the control group and 48.81 ± 10.85 µm in OSA individuals (p = 0.47). Pearson correlations between the GCIPL-GCL measurements and the main indices of SAP were not significant. CONCLUSIONS: Neither GCIPL nor GCL thickness were reduced in OSA subjects compared with healthy individuals. Retinal sensitivity evaluated with SAP was however decreased in OSA patients.

Assessment of the retinal nerve fiber layer in individuals with obstructive sleep apnea.

BACKGROUND: The effect of obstructive sleep apnea (OSA) syndrome in the peripapillary retinal nerve fiber layer (RNFL) thicknesses remains unclear. The purpose of this study was to assess RNFL measurements acquired using scanning laser polarimetry (SLP) and optical coherence tomography (OCT) in patients with OSA. METHODS: The sample of this cross-sectional study included 40 OSA patients and 45 age-matched controls, consecutively and prospectively selected. All participants underwent at least one reliable standard automated perimetry (SAP) test, while RNFL measurements were obtained using the SLP and OCT. The OSA group was divided into 3 sub-groups based on the apnea/hypopnea index (AHI): mild, moderate, or severe OSA. SAP, SLP, and OCT outcomes were compared between the control and OSA groups. The relationship between AHI and RNFL parameters was also evaluated. RESULTS: Age was not different between both groups. Mean deviation of SAP was -0.47 ± 0.9 dB and -1.43 ± 2.3 dB in the control and OSA groups, respectively (p = 0.01). RNFL thickness measured with OCT was similar between groups. OSA patients showed increased nerve fiber indicator (NFI; 20.9 ± 7.9 versus 16.42 ± 7.82; p = 0.01) and decreased superior average (59.74 ± 10.35 versus 63.73 ± 6.58; p = 0.03) obtained with SLP compared with healthy individuals. In the total sample, NFI and AHI were moderately correlated (r = 0.358; p = 0.001). In severe OSA subjects (n = 22), NFI and AHI had a Spearman correlation coefficient of 0.44 (p = 0.04). CONCLUSION: RNFL thickness measured with OCT did not differ significantly between groups. Severe OSA was related to a reduction of the RNFL thickness assessed by SLP.

Repeatability and Reproducibility of Retinal Nerve Fiber Layer Parameters Measured by Scanning Laser Polarimetry with Enhanced Corneal Compensation in Normal and Glaucomatous Eyes.

OBJECTIVE: To assess the intrasession repeatability and intersession reproducibility of peripapillary retinal nerve fiber layer (RNFL) thickness parameters measured by scanning laser polarimetry (SLP) with enhanced corneal compensation (ECC) in healthy and glaucomatous eyes. METHODS: One randomly selected eye of 82 healthy individuals and 60 glaucoma subjects was evaluated. Three scans were acquired during the first visit to evaluate intravisit repeatability. A different operator obtained two additional scans within 2 months after the first session to determine intervisit reproducibility. The intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) were calculated for all SLP parameters in both groups. RESULTS: ICCs ranged from 0.920 to 0.982 for intravisit measurements and from 0.910 to 0.978 for intervisit measurements. The temporal-superior-nasal-inferior-temporal (TSNIT) average was the highest (0.967 and 0.946) in normal eyes, while nerve fiber indicator (NFI; 0.982) and inferior average (0.978) yielded the best ICC in glaucomatous eyes for intravisit and intervisit measurements, respectively. All COVs were under 10% in both groups, except NFI. TSNIT average had the lowest COV (2.43%) in either type of measurement. Intervisit TRT ranged from 6.48 to 12.84. CONCLUSIONS: The reproducibility of peripapillary RNFL measurements obtained with SLP-ECC was excellent, indicating that SLP-ECC is sufficiently accurate for monitoring glaucoma progression.

Logistic regression analysis for early glaucoma diagnosis using optical coherence tomography.

OBJECTIVE: To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on the retinal nerve fiber layer thickness at each of the 12 clock-hour positions obtained using optical coherence tomography for discriminating between healthy eyes and eyes with early glaucomatous visual field loss. METHODS: We prospectively selected 62 consecutive healthy individuals and 73 patients with open-angle glaucoma to calculate the LDF. Another independent prospective sample of 280 healthy eyes and 302 glaucomatous eyes was used to evaluate the diagnostic accuracy of the LDF. RESULTS: The proposed function was LDF = 15.584 - (12-o'clock segment thickness x 0.032) - (7-o'clock segment thickness x 0.041) - (3-o'clock segment thickness [nasal side] x 0.121). The greatest area under the receiver operating characteristic curve was observed for our LDF in both populations: 0.962 and 0.922. Our LDF and the average thickness yielded sensitivities of 74.5% and 67.8%, respectively, at a fixed specificity of 95%. CONCLUSIONS: The LDF increased the diagnostic ability of the isolated retinal nerve fiber layer thickness at the 12 clock-hour positions. Compared with optical coherence tomography-provided parameters, our LDF had the highest sensitivities at 85% and 95% fixed specificities to discriminate between healthy and early glaucomatous eyes.

Diagnostic ability of the Heidelberg Retina Tomograph 3 for glaucoma.

PURPOSE: To compare the diagnostic ability of the Heidelberg Retina Tomograph 3 (HRT3) and the Heidelberg Retina Tomograph 2 (HRT2) for discriminating between healthy eyes and eyes with glaucomatous visual field loss. DESIGN: Retrospective cross-sectional study. METHODS: Participants were 93 healthy subjects and 90 patients with open-angle glaucoma. All participants underwent imaging of the optic nerve head with the HRT2. Afterward, HRT data also were analyzed using version 3 of the software without modifying the optic disk contour line. The receiver operating characteristic (ROC) curves between normal and glaucomatous subjects were plotted for the global stereometric parameters of both software versions. Moorfields regression analysis (MRA) and glaucoma probability score (GPS) diagnostic abilities also were compared. RESULTS: The parameters with the largest areas under the ROC curve were the Frederick S. Mikelberg (FSM) discriminant function for the HRT3 (0.948) and the vertical cup-to-disk ratio (0.914) for the HRT2. At a fixed specificity of 95%, the best sensitivity was 74.4% for the Reinhard O.W. Burk (RB) discriminant function of the HRT2 and 83.3% for the FSM discriminant function of the HRT3. The best sensitivity and specificity pairs for the HRT classifications were 85.5% and 76.3%, respectively, for overall MRA2, 84.4% and 83.8%, respectively, for overall MRA3, 93.3% and 58.0%, respectively, for the global color-coded GPS, and 84.4% and 74.1%, respectively, for the global GPS numerical value. CONCLUSIONS: At 95% fixed specificity, most HRT3 parameters exhibited at least the same sensitivity for glaucoma diagnosis as the analogous parameters for the HRT2. The diagnostic ability overall of MRA3 was similar to that of the previous version. GPS exhibited higher sensitivity and somewhat lower specificity than the MRA.

Discriminating between normal and glaucoma-damaged eyes with the Heidelberg Retina Tomograph 3.

PURPOSE: To determine and validate the diagnostic ability of a linear discriminant function (LDF) based on global stereometric parameters obtained using the Heidelberg Retina Tomograph version 3 (HRT3) for discriminating between healthy eyes and eyes with glaucomatous visual field loss. DESIGN: Cross-sectional study. PARTICIPANTS: The authors prospectively selected 81 consecutive healthy subjects and 85 consecutive patients with open-angle glaucoma. Another prospective sample of 225 normal eyes and 210 glaucoma eyes was used to evaluate how well the LDF performed in another population. METHODS: Participants were divided into 2 groups depending on the results of standard automated perimetry and intraocular pressure. All participants underwent imaging of the optic nerve head with the HRT3. MAIN OUTCOME MEASURES: The LDF was calculated according to the stepwise logistic regression results of global optic nerve head parameters and glaucoma probability score numerical values. The diagnostic accuracy of the LDF and other parameters included in the software of the HRT3 was evaluated in another independent population. RESULTS: Based on the results of the stepwise binary logistic regression analysis, the function proposed was LDF = 8.23 - 8.00 x contour line modulation temporal superior + 9.41 x cup shape measure - 4.07 x rim area. The areas under the receiver operating characteristic curve were 0.875 for the LDF, 0.845 for the Frederick S. Mikelberg (FSM) discriminant function, and 0.838 for the Reinhard O. W. Burk (RB) discriminant function. There were no significant differences between these values. The LDF and the FSM and RB discriminant functions yielded sensitivities of 74.2%, 70.4%, and 67.6%, respectively, at a fixed specificity of 85%. CONCLUSIONS: Compared with the HRT-provided parameters, the proposed LDF exhibited higher diagnostic ability than most available analyses. The LDF had a better sensitivity and specificity balance than the FSM and RB discriminant functions, regardless of optic disc size.

Can frequency-doubling technology and short-wavelength automated perimetries detect visual field defects before standard automated perimetry in patients with preperimetric glaucoma?

PURPOSE: To assess the ability of frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) to detect glaucomatous damage in preperimetric glaucoma subjects. PARTICIPANTS: Two hundred seventy-eight eyes of 278 subjects categorized as normal eyes [n=98; intraocular pressure <20 mm Hg, normal optic disc appearance, and standard automated perimetry (SAP)]; preperimetric glaucoma eyes (n=109; normal SAP and retinal nerve fiber layer defects or localized optic disc notching and thinning); and glaucoma patients (n=71; intraocular pressure >21 mm Hg, optic disc compatible with glaucoma, and abnormal SAP). METHODS: The preperimetric glaucoma group underwent at least 2 reliable full-threshold 24-2 Humphrey SAPs, full-threshold C-20 FDT, full-threshold 24-2 SWAP, optic disc topography using the Heidelberg Retina Tomograph II, laser polarimetry using the GDx VCC, and Optical Coherence Tomography (Zeiss Stratus OCT 3000). Receiver operating characteristic curves were plotted for the main Heidelberg Retina Tomograph, Optical Coherence Tomography, and GDx VCC parameters for the normal and glaucoma patients. The area under the receiver operating characteristic curve was used to determine the parameters indicating glaucomatous damage in the optic disc or retinal nerve fiber layer, which were used to establish additional subgroups of patients with preperimetric glaucoma. FDT and SWAP sensitivities were calculated for the patient subsets with structural damage and normal SAP. RESULTS: At least 20% of the patients with preperimetric glaucoma demonstrated functional losses in FDT and SWAP. The more severe the structural damage, the greater the sensitivity for detecting glaucomatous visual field losses. CONCLUSIONS: FDT and SWAP detect functional losses in cases of suspected glaucoma before glaucomatous losses detected by SAP.

Diagnostic ability of Heidelberg Retina Tomograph 3 classifications: glaucoma probability score versus Moorfields regression analysis.

PURPOSE: To evaluate the usefulness of the glaucoma probability score (GPS), which does not require manual outlining of the disc boundaries, and the Moorfields regression classification (MRA), which requires manual outlining of the disc boundaries, for discriminating between healthy and glaucomatous eyes, using the Heidelberg Retina Tomograph. DESIGN: Cross-sectional study. PARTICIPANTS: We prospectively selected 71 consecutive healthy subjects and 115 consecutive patients with open-angle glaucoma. METHODS: Participants were divided into 2 groups depending on the results of standard automated perimetry and intraocular pressure. All participants underwent imaging of the optic nerve head with the Heidelberg Retina Tomograph 3. All tests were performed within 1 month of each subject's date of enrollment into the study by examiners masked to the other findings. MAIN OUTCOME MEASURES: The sensitivity and specificity of all parameters of the MRA and GPS classifications were calculated. The diagnostic accuracy at different severities of glaucoma and optic disc sizes was also evaluated. Receiver operating characteristic curves were plotted for the GPS values. RESULTS: The MRA global classification had a sensitivity of 73.9% and a specificity of 91.5%. The GPS global classification had a sensitivity of 58.2% and a specificity of 94.4%. The GPS had slightly higher sensitivity and somewhat lower specificity than the MRA when there was mild damage indicated by visual field tests. The MRA had the best discrimination capability for moderate and severe glaucoma. Both the GPS and MRA had lower sensitivity and higher specificity for small optic discs (<1.7 mm2) compared with medium and large discs. CONCLUSIONS: In general, the diagnostic performance of the GPS was similar to that of the MRA. The diagnostic accuracy of both classifications depends on the optic disc size and the glaucoma severity.

Frequency-doubling technology: searching for the optimum diagnostic criteria for glaucoma.

PURPOSE: To determine the diagnostic criteria of perimetry using frequency-doubling technology (FDT) with the best possible sensitivity-specificity balance for glaucoma diagnosis. METHODS: A total of 92 healthy control subjects and 110 patients with varying degrees of glaucomatous visual field loss on standard automated perimetry (SAP) were used to obtain the best diagnostic criterion for the disease, by using screening C-20-1 and threshold C-20 strategies from original FDT perimetry. Another prospective sample of 52 normal eyes and 64 glaucoma eyes was used to test how well this optimum criterion performs in other populations. Receiver operating characteristic (ROC) curves were plotted for the number of altered points at each level of probability for the C-20-1 and threshold C-20 modes. In addition, ROC curves were calculated for the global indices of the threshold C-20 strategy. RESULTS: The best criterion for the C-20-1 strategy is the presence of one or more altered points with p < 1% (57.81% sensitivity and 100% specificity). The optimum criteria for glaucoma diagnosis for the threshold C-20 strategy are the presence of five or more altered points with p < 5% and/or two or more altered points with p < 2% and/or at least one altered point with p < 1% at any location (79.68% sensitivity and 94.2% specificity). CONCLUSIONS: By using the C-20-1 strategy, a p < 1% defect anywhere showed 100% specificity with the lowest test duration. The criteria proposed for the threshold C-20 algorithm presented a good sensitivity-specificity balance. The threshold C-20 test provides higher sensitivity than the C-20-1 strategy but takes about five times longer to perform.