Structure–Function Relationships between Spectral-Domain OCT and Standard Achromatic Perimetry

Prediction of Visual Field Progression with Baseline and Longitudinal Structural Measurements Using Deep Learning

PURPOSE

Identifying glaucoma patients at high risk of progression based on widely available structural data is an unmet task in clinical practice. We test the hypothesis that baseline or serial structural measures can predict visual field (VF) progression with deep learning (DL).

DESIGN

Development of a DL algorithm to predict VF progression.

METHODS

3,079 eyes (1,765 patients) with various types of glaucoma and ≥5 VFs, and ≥3 years of follow-up from a tertiary academic center were included. Serial VF mean deviation (MD) rates of change were estimated with linear-regression. VF progression was defined as negative MD slope with p<0.05. A Siamese Neural Network with ResNet-152 backbone pre-trained on ImageNet was designed to predict VF progression using serial optic-disc photographs (ODP), and baseline retinal nerve fiber layer (RNFL) thickness. We tested the model on a separate dataset (427 eyes) with RNFL data from different OCT. The Main Outcome Measure was Area under ROC curve (AUC).

RESULTS

Baseline average (SD) MD was 3.4 (4.9)dB. VF progression was detected in 900 eyes (29%). AUC (95% CI) for model incorporating baseline ODP and RNFL thickness was 0.813 (0.757-0.869). After adding the second and third ODPs, AUC increased to 0.860 and 0.894, respectively (p<0.027). This model also had highest AUC (0.911) for predicting fast progression (MD rate <1.0 dB/year). Model's performance was similar when applied to second dataset using RNFL data from another OCT device (AUC=0.893; 0.837-0.948).

CONCLUSIONS

DL model predicted VF progression with clinically relevant accuracy using baseline RNFL thickness and serial ODPs and can be implemented as a clinical tool after further validation.

Morphology of the optic nerve head and factors affecting it in the Northern Finland birth cohort

PURPOSE

To assess topographic characteristics of the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) and study the effect of ocular and physiological factors on them in a middle-aged population.

METHODS

A 1552-person randomised sample from Northern Finland population aged 45-49 was examined. Laser scanning tomography and optical coherency tomography were performed to obtain measurements for ONH and RNFL morphology. Measurements of the RNFL included global thickness and the six zones used in automated structure-function analysis (S-F analysis). Influence of central corneal thickness (CCT), refractive correction, intraocular pressure (IOP), anterior chamber angle, gender, blood pressure, height, weight and body mass index (BMI) on tomographic data was analysed.

RESULTS

The optic disc area had a strong correlation with all other parameters of ONH morphology (R = 0.261 to 0.706) as did spherical equivalent (R = -0.280 to 0.280). The correlations between ONH and RNFL measurements were weaker (R = 0.057 to 0.180). Gender, CCT, anterior chamber angle, blood pressure, height and BMI had statistically significant, yet feeble, correlations with a number of ONH parameters.

CONCLUSION

Other than spherical equivalent, the studied anatomical and physiological attributes had little predictive value on the ONH morphology. The optic disc area itself had a significant effect on other measurements of ONH tomography and should be taken into consideration when the thresholds for normal ONH morphology are calculated.

Macular integrity assessment microperimeter, Humphrey field analyzer and OCT in glaucoma practice: a correlation study

OBJECTIVE

To compare and correlate retinal sensitivities measured with macular integrity assessment microperimetry (MAIA-MP) and Humphrey field analyzer (HFA) 10-2 tests with structural parameters obtained from optical coherence tomography (OCT) in primary open-angle glaucoma (POAG) and ocular hypertension.

METHODS

This study included 63 participants (22 with POAG, 20 with ocular hypertension, and 21 control individuals). All participants underwent HFA 10-2 and MAIA-MP (macular retinal sensitivity tests) and measurements for optic nerve head (ONH), peripapillary retinal nerve fibre layer thickness (PRNFLT), and ganglion cell inner plexiform layer thickness (GCIPLT) using OCT. The relationship between macular retinal sensitivity and OCT parameters was evaluated by Pearson correlation analysis and linear regression modelling.

RESULTS

POAG cases had a strong association between the MAIA-MP and ONH parameters (optic disc area [ODA], p = 0.037; cup volume, p = 0.043), PRNFLT (average, p = 0.009; inferior PRNFLT, p = 0.004), and GCIPLT in all macula sectors (p ≤ 0.005 for all). HFA 10-2 had a moderate correlation with the ONH parameters (cup-to-disc ratio [CDR], p = 0.042; vertical CDR, p = 0.037; cup volume, p = 0.037; ODA, p = 0.014), PRNFLT (average, inferior, and nasal, p < 0.05 for all), and GCIPLT in all macula sectors (p < 0.005 for all). OHT cases had a weak correlation between HFA 10-2 and nasal and superior PRNFLTs (p = 0.035 and p = 0.047, respectively).

CONCLUSION

MAIA-MP and HFA 10-2 functional parameters have strong correlations with the structural parameters obtained by OCT in POAG cases. Both devices are useful in assessing the central visual field in glaucoma, with MAIA-MP potentially beneficial in patients with limited cooperation or poor vision.

A Global and Sector-Based Comparison of OCT Angiography and Visual Field Defects in Glaucoma

Purpose. To evaluate the correlation of optical coherence tomography angiography (OCTA) and spectral-domain optical coherence tomography (SD-OCT) with visual field for global and sector-based indices among glaucoma and glaucoma-suspected eyes. Patients and Methods. This is a retrospective study, and in total, 48 glaucoma eyes and 31 glaucoma suspect eyes were included. The correlation between visual field parameters and radial peripapillary capillary (RPC) vessel density via OCTA was compared to the correlation with retinal nerve fiber layer (RNFL) thickness via SD-OCT. The RPC vessel density and RNFL thickness were divided into eight sectors, which included the temporal upper, temporal lower, superotemporal, inferotemporal, superonasal, inferonasal, nasal upper, and nasal lower sectors. Pearson correlations with 95% confidence intervals were calculated with resampling, and correlations were compared with a Fisher Z transformation. Results. Both RPC vessel density (R = 0.63, 95% CI [0.24, 0.86]) and RNFL thickness (R = 0.49, 95% CI [0.23, 0.69]) were correlated with the mean deviation when comparing global indices of glaucoma patients. In glaucoma suspects, the correlations between the mean deviation and RPC vessel density (R = 0.21, 95% CI [−0.05, 0.49]) and RNFL thickness (R = 0.01, 95% CI [−0.35, 0.39]) were not significant. Glaucoma eyes had the highest correlation between the mean sensitivity and RPC vessel density and RNFL thickness for the superotemporal, superonasal, temporal upper, and inferotemporal sectors. Conclusion. Across a diverse population and heterogeneous glaucoma types, RPC vessel density measurements correlate with global and sector-wise visual field indices similar to RNFL thickness.

Virtual Reality Oculokinetic Perimetry Test Reproducibility and Relationship to Conventional Perimetry and OCT

Purpose

Vivid Vision Perimetry (VVP; Vivid Vision, Inc) is a novel method for performing in-office and home-based visual field assessment using a virtual reality platform and oculokinetic perimetry. Here we examine the reproducibility of VVP Swift and compare results with conventional standard automated perimetry (SAP) and spectral-domain (SD) OCT.

Design

Cross-sectional study.

Participants

Fourteen eyes of 7 patients with open-angle glaucoma (OAG) (average age, 64.6 years; 29% women) and 10 eyes of 5 patients with suspected glaucoma (average age, 61.8 years; 40% women) were enrolled.

Methods

Patients with OAG and suspected glaucoma were enrolled prospectively and underwent 2 VVP Swift examinations. Results were compared with 1 conventional SAP examination (Humphrey Visual Field [HVF]; Zeiss) and 1 SD OCT examination.

Main Outcome Measures

Mean sensitivity (in decibels) obtained for each eye in 2 VVP Swift test sessions and a conventional SAP examination, thickness of the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) for the SD OCT examination, and mean test durations of the VVP Swift and SAP examinations.

Results

The mean test duration of VVP Swift in both eyes (8.5 minutes) was significantly shorter (P < 0.001) than SAP (12.2 minutes). The average absolute difference of the mean sensitivity between the 2 VVP Swift sessions was found to be 0.73 dB (95% confidence interval [CI], 0.40–1.06). A statistically significant association was found between average mean sensitivity measurements from the VVP and mean deviation (MD) measurements obtained by the HVF with a Pearson correlation coefficient of 0.86 (95% CI, 0.70–0.94; P < 0.001). Mean visual sensitivity measurements from the VVP Swift test were significantly associated with average RNFL thickness (r = 0.66; P = 0.014) and GCC thickness (r = 0.63; P = 0.02), whereas the correlation coefficients between HVF MD and RNFL and GCC were 0.86 (P < 0.001) and 0.83 (P < 0.001), respectively.

Conclusions

Our results demonstrated that the VVP Swift test can generate reproducible results and is comparable with conventional SAP. This suggests that the device can be used by clinicians to assess visual function in glaucoma.

Relationship Between Flicker Modulation Sensitivity and Retinal Ganglion Cell Related Layer Thicknesses

Purpose

Early detection of structural changes in retinal ganglion cells (RGCs) and corresponding changes in visual function is important in early degenerative diseases of the retina, but the sensitivity of both measurements is limited by the inherent variability in healthy subjects. This study investigates the relationships between RGC-related layer thicknesses and foveal and parafoveal flicker modulation sensitivity (FMS) across photopic and mesopic light levels in healthy subjects.

Methods

Photopic and mesopic FMS was measured in 56 young adults, at the point of fixation and at an eccentricity of 5 degrees, in each of the four quadrants. Spectral-domain optical coherence tomography (SD-OCT) was used to measure retinal thicknesses. Relationships between foveal and parafoveal FMS and the retinal thickness in the corresponding region were examined after adjusting for confounding variables.

Results

Total macular and inner retinal layer (IRL) thicknesses in the parafoveal ring were significant predictors of photopic (P = 0.034) and mesopic (P = 0.034) parafoveal FMS, respectively. The superior peripapillary retinal nerve fiber layer (pRNFL) thickness was a contributing factor to the inferior parafoveal FMS (photopic: P = 0.006 and mesopic: P = 0.021) and the inferior pRNFL thickness was also a contributing factor to the superior parafoveal FMS (photopic: P < 0.001 and mesopic: P = 0.015).

Conclusions

The pRNFL thicknesses predict parafoveal FMS for both mesopic and photopic conditions in healthy eyes.

Translational Relevance

The measurement of rapid flicker sensitivity in the parafoveal retina together with the pRNFL thickness profiles measured before the onset of disease, may provide a more sensitive biomarker for detecting loss of sensitivity caused by the earliest neurodegenerative changes in the eyes.

Combined structure-function analysis in glaucoma screening

AIM

To assess the applicability of a structure-function (S-F) analysis combining spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry (SAP) in glaucoma screening in a middle-aged population.

METHODS

A randomised sample of 3001 Caucasian participants aged 45-49 years of the Northern Finland Birth Cohort Eye Study was examined. We performed an eye examination, including 24-2 SAP, optic nerve head (ONH) and retinal nerve fibre layer (RNFL) photography and SD-OCT of the peripapillary RNFL. The S-F report was generated by Forum Glaucoma Workplace software. OCT, SAP and the S-F analysis were evaluated against clinical glaucoma diagnosis, that is, the positive '2 out of 3' rule based on the clinician's evaluation of ONH and RNFL photographs and visual fields (VFs).

RESULTS

At a specificity of 97.5%, the sensitivity for glaucomatous damage was 26% for abnormal OCT, 35% for SAP and 44% for S-F analysis. Estimated areas under the curve were 0.74, 0.85 and 0.76, and the corresponding positive predictive values were 8 %, 10% and 12%, respectively. By applying a classification tree approach combining OCT, SAP and defect localisation data, a sensitivity of 77% was achieved at 90% specificity. In a localisation analysis of glaucomatous structural and functional defects, the correlation with glaucoma increased significantly if the abnormal VF test points were located on borderline or abnormal OCT zones.

CONCLUSION

SAP performs slightly better than OCT in glaucoma screening of middle-aged population. However, the diagnostic capability can be improved by S-F analysis.

Relationship between peripapillary vessel density and visual function based on Garway-Heath sectorization in open-angle glaucoma

Purpose:

To investigate the relationship between peripapillary vessel density (pVD) and visual field sensitivity (VFS) and between peripapillary retinal nerve fiber layer thickness (pRNFLT) and VFS, based on Garway-Heath sectorization in open-angle glaucoma patients.

Methods:

Sixty-six eyes of healthy subjects and 84 eyes of glaucoma subjects were included. All subjects underwent several eye examinations, including standard automated perimetry and optical coherence tomography angiography. Sectoral structure-function relationships based on the Garway-Heath sectorization were compared among normal subjects, the ‘mild glaucoma,’ and ‘moderate-to-severe glaucoma’ group. Multivariate analyses were performed for each sector to determine the factors related to VFS. The diagnostic abilities of vessel density parameters and RNFLT were evaluated by calculating the area under the receiver operating characteristic curves (AUROC).

Results:

The correlation between pVD-VFS and pRNFLT-VFS was statistically significant in the glaucoma group independent of the VFS sector. In the glaucoma group, VFS in the temportal sector was statistically related in a multivariate model to pVD, pRNFLT and age (R² = 0.721; P = 0.007, < 0.001, .15, respectively). We found pRNFLT and age were significantly associated with VFS in glaucoma. The AUROC values of pVD in the inferotemporal sector of the total, mild, and moderate-to-severe glaucoma (0.843, 0.714, and 0.972, respectively) were comparable to pRNFLT in this sector (0.833, 0.718, 0.948, respectively).

Conclusion:

Since the relationship between pVD and VFS in the papillomacular area was significant, measuring pVD and RNFLT in the corresponding area will be valuable in expanding our pathophysiologic knowledge of the paracentral field defects in glaucoma.

Structure-Function Mapping Using a Three-Dimensional Neuroretinal Rim Parameter Derived From Spectral Domain Optical Coherence Tomography Volume Scans

Purpose

To assess the structure-function relationship in glaucoma using Humphrey visual field (HVF) perimetry and a three-dimensional neuroretinal rim parameter derived from spectral domain optical coherence tomography (SD-OCT) volume scans.

Methods

Structure-function correlation was analyzed globally and regionally (four quadrants and four sectors). Structural data included peripapillary retinal nerve fiber layer (RNFL) thickness and minimum distance band (MDB) neuroretinal rim thickness, defined as the shortest distance between the inner cup surface and the outer retinal pigment epithelium/Bruch's membrane complex. Logarithmic regression analyses were performed and Pearson correlation coefficients determined to assess relationship strength.

Results

The study consisted of 102 open-angle glaucoma patients and 58 healthy subjects. The Pearson correlation coefficient for global MDB thickness (R = 0.585) was higher than for global RNFL thickness (R = 0.492), but the difference was not statistically significant (P = 0.18). The correlation coefficients for regional MDB thicknesses and corresponding HVF sensitivities were higher than those for regional RNFL thicknesses and HVF in six out of eight regions (P = 0.08 to 0.47). In the remaining two out of eight regions, the correlation coefficients were higher for RNFL thickness than for MDB thickness (P = 0.15 to 0.20).

Conclusions

Three-dimensional MDB neuroretinal rim thickness relates to visual function as strongly as the most commonly used SD-OCT parameter for glaucoma, two-dimensional peripapillary RNFL thickness.

Translational Relevance

This paper illustrates the potential for 3D OCT algorithms to improve in vivo imaging in glaucoma.

Mapping the binocular scotoma in macular degeneration

When the scotoma is binocular in macular degeneration (MD), it often obscures objects of interest, causing individuals to miss information. To map the binocular scotoma as precisely as current methods that map the monocular scotoma, we propose an iterative eye-tracker method. Study participants included nine individuals with MD and four age-matched controls. We measured the extent of the monocular scotomata using a scanning laser ophthalmoscope/optical coherence tomography (SLO/OCT). Then, we precisely mapped monocular and binocular scotomata with an eye tracker, while fixation was monitored. Participants responded whenever they detected briefly flashed dots, which were first presented on a coarse grid, and then at manually selected points to refine the shape and edges of the scotoma. Monocular scotomata measured in the SLO and eye tracker are highly similar, validating the eye-tracking method for scotoma mapping. Moreover, all participants used clustered fixation loci corresponding to their dominant preferred fixation locus. Critically, for individuals with binocular scotomata, the binocular map from the eye tracker was consistent with the overlap of the monocular scotoma profiles from the SLO. Thus, eye-tracker-based perimetry offers a reliable and sensitive tool for measuring both monocular and binocular scotomata, unlike the SLO/OCT that is limited to monocular viewing.

Visual Field Cluster Map Corresponding to Bruch Membrane Opening-minimum Rim Area Sectors in Open-angle Glaucoma

PRéCIS:: We generated a new visual field (VF) cluster map corresponding to Bruch membrane opening-minimum rim area (BMO-MRA) sectors, which described in detail the structure-function relationships between the optic nerve head and VF in patients with open-angle glaucoma.

PURPOSE

The purpose of this study was to investigate the structure-function relationship between BMO-MRA and VF in patients with open-angle glaucoma.

MATERIALS AND METHODS

We retrospectively reviewed 67 eyes of 50 patients with open-angle glaucoma who underwent spectral-domain optical coherence tomography for BMO-MRA and the Humphrey VF test. BMO-MRA of the glaucomatous optic nerve head was divided into 12 sectors. The correlation between BMO-MRA sectors and the VF points was analyzed to generate a new VF cluster map.

RESULTS

Forty-three of the 52 VF points showed a significant correlation with at least 1 BMO-MRA sector. The VF cluster map was generated using the BMO-MRA sectors and each VF point that showed the most correlation. The superior hemifield correlated with 5, 6, 7, and 8 o'clock positions (ρ=0.312 to 0.710), whereas the inferior hemifield correlated with 10, 11, 12, and 2 o'clock positions (ρ=0.241 to 0.483). The VF cluster maps of superior and inferior hemifields showed different configurations of VF clusters and topographical relationships with the glaucomatous optic nerve head.

CONCLUSION

The newly generated VF cluster map corresponding to BMO-MRA sectors showed a significant structure-function relationship and could be useful in the diagnosis and evaluation of glaucoma.

Attention-Guided 3D-CNN Framework for Glaucoma Detection and Structural-Functional Association Using Volumetric Images

The direct analysis of 3D Optical Coherence Tomography (OCT) volumes enables deep learning models (DL) to learn spatial structural information and discover new bio-markers that are relevant to glaucoma. Downsampling 3D input volumes is the state-of-art solution to accommodate for the limited number of training volumes as well as the available computing resources. However, this limits the network's ability to learn from small retinal structures in OCT volumes. In this paper, our goal is to improve the performance by providing guidance to DL model during training in order to learn from finer ocular structures in 3D OCT volumes. Therefore, we propose an end-to-end attention guided 3D DL model for glaucoma detection and estimating visual function from retinal structures. The model consists of three pathways with the same network architecture but different inputs. One input is the original 3D-OCT cube and the other two are computed during training guided by the 3D gradient class activation heatmaps. Each pathway outputs the class-label and the whole model is trained concurrently to minimize the sum of losses from three pathways. The final output is obtained by fusing the predictions of the three pathways. Also, to explore the robustness and generalizability of the proposed model, we apply the model on a classification task for glaucoma detection as well as a regression task to estimate visual field index (VFI) (a value between 0 and 100). A 5-fold cross-validation with a total of 3782 and 10,370 OCT scans is used to train and evaluate the classification and regression models, respectively. The glaucoma detection model achieved an area under the curve (AUC) of 93.8% compared with 86.8% for a baseline model without the attention-guided component. The model also outperformed six different feature based machine learning approaches that use scanner computed measurements for training. Further, we also assessed the contribution of different retinal layers that are relevant to glaucoma. The VFI estimation model achieved a Pearson correlation and median absolute error of 0.75 and 3.6%, respectively, for a test set of size 3100 cubes.

Longitudinal Macular Structure-Function Relationships in Glaucoma

PURPOSE

To investigate the relationship between longitudinal changes in macular thickness measurements from OCT and changes in central visual field (VF) in patients with glaucoma with central or advanced damage at baseline.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

A total of 116 eyes with ≥3 years of follow-up and ≥5 macular OCT images and central 10° VF tests were selected.

METHODS

OCT superpixels and VF locations were matched correcting for retinal ganglion cell (RGC) displacement. Superpixel thickness and VF total deviation (TD) values, in both logarithmic and linear scales, were averaged within 3 eccentricities (3.4°, 5.6°, and 6.8°) and superior and inferior hemiretinas and hemifields. We estimated pointwise TD rates of change and rates of change at superpixels for full macular thickness (FMT), ganglion cell complex (GCC), ganglion cell inner plexiform layer (GCIPL), and ganglion cell layer (GCL). Correlation of structure-function (SF) rates of change was investigated with parametric tests. We compared the proportion of worsening and positive slopes for superpixels and VF test locations (negative vs. positive rates of change with P < 0.05) throughout the follow-up period. Permutation analyses were used to control specificity.

MAIN OUTCOME MEASURES

Magnitude of correlation between structural and functional rates of change and proportion of worsening and positive slopes as a function of follow-up time.

RESULTS

The median (interquartile range) follow-up and number of exams were 4.2 (3.7-4.6) years and 8 (7-9), respectively. The highest correlation of change rates was observed at 3.4° and 5.6° eccentricities (r = 0.24, 0.41, 0.40, and 0.40 for FMT, GCC, GCIPL, and GCL for 3.4° eccentricity and r = 0.28, 0.32, 0.31, and 0.32 for FMT, GCC, GCIPL, and GCL for 5.6° eccentricity, respectively). Although GCC measures demonstrated the highest overall longitudinal SF correlations, the differences were not statistically significant. Significant structural worsening was more frequently detected than functional deterioration at 3- and 5-year time points (P < 0.025). Permutation analyses also confirmed this finding.

CONCLUSIONS

Correlations between central structural and functional rates of change were weak to fair in this cohort. Structural changes were detected more frequently than functional changes. Measurements of both structure and function are required for optimal detection of central progression.

Estimating Visual Field Mean Deviation using Optical Coherence Tomographic Nerve Fiber Layer Measurements in Glaucoma Patients

To construct an optical coherence tomography (OCT) nerve fiber layer (NFL) parameter that has maximal correlation and agreement with visual field (VF) mean deviation (MD). The NFL_MD parameter in dB scale was calculated from the peripapillary NFL thickness profile nonlinear transformation and VF area-weighted averaging. From the Advanced Imaging for Glaucoma study, 245 normal, 420 pre-perimetric glaucoma (PPG), and 289 perimetric glaucoma (PG) eyes were selected. NFL_MD had significantly higher correlation (Pearson R: 0.68 vs 0.55, p < 0.001) with VF_MD than the overall NFL thickness. NFL_MD also had significantly higher sensitivity in detecting PPG (0.14 vs 0.08) and PG (0.60 vs 0.43) at the 99% specificity level. NFL_MD had better reproducibility than VF_MD (0.35 vs 0.69 dB, p < 0.001). The differences between NFL_MD and VF_MD were -0.34 ± 1.71 dB, -0.01 ± 2.08 dB and 3.54 ± 3.18 dB and 7.17 ± 2.68 dB for PPG, early PG, moderate PG, and severe PG subgroups, respectively. In summary, OCT-based NFL_MD has better correlation with VF_MD and greater diagnostic sensitivity than the average NFL thickness. It has better reproducibility than VF_MD, which may be advantageous in detecting progression. It agrees well with VF_MD in early glaucoma but underestimates damage in moderate~advanced stages.

Longitudinal Macular Structure-Function Relationships in Glaucoma and Their Sources of Variability

PURPOSE

To review central structure-function (SF) relationships in glaucoma; to compare contributions of within-session and between-session variability to total variability of macular optical coherence tomography (OCT) thickness measurements; and to test the hypothesis that longitudinal within-eye variability of central SF relationships is smaller than between-individual variability.

METHODS

We reviewed the pertinent literature on central SF relationships in glaucoma. Thirty-eight eyes (20 normal or glaucoma subjects) had ×3 macular images per session over 3 sessions, and superpixels thickness measurements for ganglion cell layer (GCL), ganglion cell/inner plexiform layer (GCIPL), ganglion cell complex (GCC), and full macular thickness (FMT) were exported. Linear mixed models were used for estimating contributions of between- and within-session variability to total thickness variability. One hundred twenty eyes with ≥3 10° visual fields (VFs)/OCT images were enrolled for the longitudinal study. We investigated within-eye longitudinal SF relationships (GCIPL thickness vs VF total deviations) with a change-point regression model and compared within-eye to between-individual variabilities with components-of-variance models.

RESULTS

In the cross-sectional study, the between-session component contributed 8%, 11%, 11%, and 36% of total variability for GCL, GCIPL, GCC, and FMT, respectively. In the longitudinal study, between-individual variability explained 78%, 77%, and 67% of total SF variability at 3.4°, 5.6°, and 6.8° eccentricities, respectively (P < .05). SF relationships remained stable over time within individual eyes.

CONCLUSIONS

Within-session variability accounts for most of macular thickness variability over time. Longitudinal within-eye SF variability is smaller than between-individual variability. Study of within-eye SF relationships could help clinicians better understand SF linking in glaucoma and help refine progression algorithms. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Association of Functional Loss With the Biomechanical Response of the Optic Nerve Head to Acute Transient Intraocular Pressure Elevations

Importance

The acute biomechanical response of the optic nerve head (ONH) to intraocular pressure (IOP) elevations may serve as a biomarker for the development and progression of glaucoma.

Objective

To evaluate the association between visual field loss and the biomechanical response of the ONH to acute transient IOP elevations.

Design, Setting, and Participants

In this observational study, 91 Chinese patients (23 with primary open-angle glaucoma [POAG], 45 with primary angle-closure glaucoma, and 23 without glaucoma) were recruited from September 3, 2014, through February 2, 2017. Optical coherence tomography scans of the ONH were acquired at baseline and at 2 sequential IOP elevations (0.64 N and then 0.90 N, by applying forces to the anterior sclera using an ophthalmodynamometer). In each optical coherence tomography volume, lamina cribrosa depth (LCD) and minimum rim width (MRW) were calculated. The mean deviation (MD) and the visual field index (VFI), as assessed by automated perimetry, were correlated with IOP-induced changes of LCD and MRW globally and sectorially.

Main Outcomes and Measures

The LCD, MRW, MD, and VFI.

Results

Among the 91 patients, 39 (42.9%) were women; the mean (SD) age was 65.48 (7.23) years. In POAG eyes, a greater change in LCD (anterior displacement) was associated with worse MD and VFI (R = -0.64; 95% CI, -0.97 to -0.31; P = .001; and R = -0.57; 95% CI, -0.94 to -0.19; P = .005, respectively) at the first IOP elevation, and a greater reduction in MRW was also associated with worse MD and VFI (first IOP elevation: R = -0.48; 95% CI, -0.86 to -0.09; P = .02; and R = -0.57; 95% CI, -0.94 to -0.20; P = .004, respectively; second IOP elevation: R = -0.56; 95% CI, -0.98 to -0.13; P = .01; and R = -0.60; 95% CI, -1.03 to -0.17; P = .008, respectively), after adjusting for age, sex, and baseline IOP. A correlation was found between the reduction in MRW in the inferior-temporal sector and the corresponding visual field cluster in POAG eyes at the second elevation (ρ = -0.55; 95% CI, -0.78 to -0.18; P = .006).

Conclusions and Relevance

The biomechanical response of the ONH to acute IOP elevations was associated with established visual field loss in POAG eyes, but not in primary angle-closure glaucoma eyes. This suggests that ONH biomechanics may be related to glaucoma severity in POAG and that the 2 glaucoma subgroups exhibit inherently different biomechanical properties.

Evaluation of two-dimensional Bruch's membrane opening minimum rim area for glaucoma diagnostics in a large patient cohort

PURPOSE

To characterize the two-dimensional parameter Bruch's membrane opening minimum rim area (BMO-MRA) in spectral domain optical coherence tomography (SD-OCT) of the optic nerve head (ONH) compared to minimum rim width (BMO-MRW) and retinal nerve fibre layer (RNFL) thickness in a large patient cohort.

METHODS

Case-control, cross-sectional study of 705 eyes of 445 participants. A total of 449 eyes with glaucoma, 67 eyes with ocular hypertension and 189 healthy controls, underwent SD-OCT and confocal laser scanning tomography (CSLT), visual field testing and clinical examination. Morphometric ONH parameters, visual field function and diagnostic power were compared. Main outcome measures were SD-OCT-derived BMO-MRA, BMO-MRW, RNFL thickness and CSLT-derived rim area (DM-RA).

RESULTS

Mean ONH area was 2.11 ± 0.57 mm² ; mean BMO area was 1.89 ± 0.45 mm² . Correlation of mean deviation in visual field to morphometric parameters was ρ = 0.70, (p < 0.001) for RNFL thickness, ρ = 0.68 (p < 0.001) for BMO-MRA, ρ = 0.66 (p < 0.001) for BMO-MRW. These correlations were not significantly different (p > 0.05), while DM-RA correlated significantly worse (ρ = 0.55; p < 0.001). In receiver operating characteristics, the calculated area under the curve (AUC) and sensitivity at 90% specificity to differentiate glaucoma were 0.87% and 70.1% for BMO-MRA, 0.86% and 68.1% for RNFL thickness, 0.84% and 66.0% for BMO-MRW, 0.82% and 51.3% for DM-RA.

CONCLUSIONS

In a heterogenous clinical cohort of glaucoma patients, all analysed SD-OCT parameters excel DM-RA of CSLT. The two-dimensional parameter BMO-MRA shows comparable levels of diagnostic power to detect glaucoma compared to established parameters BMO-MRW and RNFL thickness. Given higher comparability between ONH sizes, BMO-MRA might become an additional standard tool in SD-OCT imaging for glaucoma.

Peripapillary microvasculature in the retinal nerve fiber layer in glaucoma by optical coherence tomography angiography: focal structural and functional correlations and diagnostic performance

Purpose

To quantify peripapillary microvasculature within the retinal nerve fiber layer (RNFL) in primary open-angle glaucoma (POAG) and normal eyes, determine association of perfusion parameters with structural and functional measures, and report diagnostic accuracy of perfusion parameters.

Patients and methods

POAG and normal patients underwent 6×6 mm² optic nerve head scans (Angioplex optical coherence tomography angiography [OCTA]; Cirrus HD-OCT 5000) and Humphrey Field Analyzer II-i 24-2 visual field (VF) testing. Prototype software performed semiautomatic segmentation to create RNFL en face images and quantified vessel area density (VAD), vessel skeleton density (VSD), and vessel complexity index (VCI) in the optic nerve head globally and focally. Generalized estimating equations models assessed association of OCTA parameters with VF mean deviation (MD) and RNFL thickness.

Results

Thirty-eight POAG and 17 normal eyes were studied. Global VAD, VSD, and VCI were reduced in mild POAG vs normal (P<0.02) and moderate-severe vs mild POAG (P<0.04). Stepwise focal reductions across disease stage were demonstrated for OCTA parameters in the inferior hemisphere (P<0.05); reduction in OCTA parameters in mild POAG vs normal was demonstrated in inferior and superior quadrants (P<0.05). Reduced global VF MD was associated with reduced VAD, VSD, and VCI (P=0.0007, 0.0013, <0.0001; R²=0.449, 0.312, 0.399, respectively), and global RNFL thickness was associated with VAD, VSD, and VCI (P<0.0001; R²=0.499, 0.524, 0.542), superior and inferior hemifield MD were associated with corresponding VAD, VSD, and VCI (P≤0.001; R² from 0.208 to 0.513). RNFL thickness in all quadrants was associated with corresponding OCTA parameters (P<0.05; R² from 0.213 to 0.394), except temporal VAD and VCI. Area under curves for VAD, VSD, and VCI demonstrated good diagnostic ability (0.868, 0.855, 0.868; P<0.0001).

Conclusion

Glaucomatous eyes showed stepwise reductions in RNFL microcirculation across severity; focal reductions in the inferior hemisphere and inferior and superior quadrants were most significant. OCTA parameters had stronger associations with structural rather than functional measures of glaucoma.

Visual field defects and retinal nerve fiber imaging in patients with obstructive sleep apnea syndrome and in healthy controls

Background

To assess the retinal sensitivity in obstructive sleep apnea hypopnea syndrome (OSAHS) patients evaluated with standard automated perimetry (SAP). And to correlate the functional SAP results with structural parameters obtained with optical coherence tomography (OCT).

Methods

This prospective, observational, case-control study consisted of 63 eyes of 63 OSAHS patients (mean age 51.7 ± 12.7 years, best corrected visual acuity ≥20/25, refractive error less than three spherical or two cylindrical diopters, and intraocular pressure < 21 mmHg) who were enrolled and compared with 38 eyes of 38 age-matched controls. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured by Stratus OCT and SAP sensitivities and indices were explored with Humphrey Field Analyzer perimeter. Correlations between functional and structural parameters were calculated, as well as the relationship between ophthalmologic and systemic indices in OSAHS patients.

Results

OSAHS patients showed a significant reduction of the sensitivity for superior visual field division (p = 0.034, t-student test). When dividing the OSAHS group in accordance with the severity of the disease, nasal peripapillary RNFL thickness was significantly lower in severe OSAHS than that in controls and mild-moderate cases (p = 0.031 and p = 0.016 respectively, Mann-Whitney U test). There were no differences between groups for SAP parameters.

We found no correlation between structural and functional variables. The central visual field sensitivity of the SAP revealed a poor Pearson correlation with the apnea-hipopnea index (0.284, p = 0.024).

Conclusions

Retinal sensitivity show minor differences between healthy subjects and OSAHS. Functional deterioration in OSAHS patients is not easy to demonstrate with visual field examination.

Bruch's membrane opening-based optical coherence tomography of the optic nerve head: a useful diagnostic tool to detect glaucoma in macrodiscs

PurposeTo compare Bruch's membrane opening (BMO)-based spectral domain optical coherence tomography (SD-OCT) and margin based confocal scanning laser tomography (CSLT) of the optic nerve head (ONH) to visual field function in large optic discs (macrodiscs) and to assess performance for glaucoma detection.MethodsIn a case-control, cross-sectional study, 125 eyes of 125 patients with disc size >2.45 mm², thereof 44 glaucoma and 11 ocular hypertension (OHT) patients and 70 healthy controls underwent SD-OCT and CSLT examination, visual field testing and clinical evaluation. Mean outcome measures BMO-based minimum rim width (BMO-MRW), retinal nerve fiber layer thickness (RNFLT) in SD-OCT, and rim area measured in CSLT were compared and correlated to visual field function.ResultsAll participants had a mean disc area of 2.91±0.38 mm² in CSLT and a BMO area of 2.45±0.39 mm² (r=0.76;P<0.001). In glaucoma patients, visual field mean deviation was -10.0±6.1 dB. Global BMO-MRW correlated better to visual field function (Spearman's Rho (ρ)=0.71; P<0.001) than RNFLT (ρ=0.52;P<0.001) and CSLT rim area (ρ=0.63; P<0.001). BMO-MRW was significantly decreased with higher visual field loss (P<0.001). In ROC analysis, diagnostic power to differentiate glaucoma patients and healthy controls was highest for BMO-MRW (Area under curve, AUC=0.96; sensitivity at 95% specificity=82%). Rim area in CSLT (AUC=0.91; sensitivity=61.0%; P=0.04) and RNFLT (AUC=0.89; sensitivity=61%; P=0.01) were significantly less powerful.ConclusionsIn macrodiscs, BMO-MRW has the best diagnostic power to discriminate glaucoma patients from normal controls compared to RNFLT and rim area in CSLT. Additionally, BMO-MRW seems to reflect the structure-function relationship better than the other two parameters.

Morphology of the optic nerve head in glaucomatous eyes with visual field defects in superior or inferior hemifield

PURPOSE

To evaluate the morphology of optic nerve head (ONH) and border tissue (BT) of Elschnig in glaucomatous eyes with visual field defects in superior or inferior hemifield.

METHODS

In a case-control study, we included 25 patients with superior arcuate scotoma, 25 patients with inferior arcuate scotoma, and 25 healthy controls. They received visual field testing, measurement of peripapillary retinal nerve fiber layer (RNFL) thickness, and ONH examination in a radial pattern with spectral-domain optical coherence tomography. In each ONH scan, the length of Bruch membrane opening (BMO) and BT were measured. Pattern deviation of 6 areas of the visual field and RNFL thickness in corresponding sectors was calculated.

RESULTS

Mean BMO length did not differ between groups. Compared with controls, glaucomatous eyes with superior scotoma had a greater BT length in inferior sectors (p<0.001), and eyes with inferior scotoma had a greater BT length in superotemporal sectors (p = 0.006). In both groups, a significant correlation was found between BT length and pattern deviation and RNFL thickness of corresponding sectors of superior and inferior hemifields.

CONCLUSIONS

In patients with arcuate scotoma in one hemifield, the length of the BT correlates with glaucomatous anatomical and functional damage.

5-year disease progression of patients across the glaucoma spectrum assessed by structural and functional tools

Background

Assessment of spectral-domain optical coherence tomography (SD-OCT) compared with visual fields, to detect progression across the glaucoma spectrum.

Methods

In this study, adult glaucoma suspects and patients, with baseline retinal nerve fibre layer (RNFL) thickness on SD-OCT and reliable visual field (VF) tests on Humphrey Field Analyser (HFA) prior to March 2010, were recruited. Functional and structural progression over at least 5 years was compared using Glaucoma Progression Analysis (GPA) and VF index (VFI) on HFA and Guided Progression Analysis (GPA-OCT) on SD-OCT, respectively. Agreement of progression detection between the two modalities was computed using κ statistics.

Results

122 subjects (63 glaucoma suspects; 59 glaucoma patients) were enrolled. Of 18 suspects who progressed to glaucoma, 13 showed progression by GPA-OCT, 4 by GPA, 7 by VFI and 2 were concordant. In the 14 glaucoma patients who progressed, GPA-OCT detected progression in 6, GPA in five and VFI in six. GPA-OCT had poor agreement with GPA in glaucoma suspects (Kappa 0.15; p=0.13) and patients (Kappa 0.10; p=0.45). VFI had better agreement with GPA-OCT in glaucoma suspects (Kappa 0.34; p=0.01) than glaucoma patients (Kappa 0.12; p=0.36). Progressors by VF in both groups had similar percentage change from baseline RNFL thickness (−9.9% vs −8.6% p=0.46), even though the absolute change was significantly greater in suspects(−8.75µ vs−6.4µ p=0.03).

Conclusion

Structural change appears to be more useful to detect progression in glaucoma suspects, while functional change is a better indicator as the disease progresses. Percentage change from baseline RNFL thickness was a better measure than absolute change in RNFL.

Structure-Function Relationships in Perimetric Glaucoma: Comparison of Minimum-Rim Width and Retinal Nerve Fiber Layer Parameters

Purpose

To test the hypotheses that: (1) structure–function (SF) relationships between visual fields (VF) and Bruch's membrane opening-based minimum rim width (BMO-MRW) measurements are superior to those for peripapillary retinal nerve fiber layer (pRNFL) in perimetric glaucoma; (2) BMO-MRW measurements may extend the utility of structural measurement across the range of glaucoma severity; and (3) to estimate the influence of Bruch's membrane opening (BMO) size on BMO-MRW measurements.

Methods

One hundred eight perimetric glaucoma eyes (68 patients) with good quality spectral-domain optical coherence tomography images of the optic disc and pRNFL, and reliable VF within 6 months were recruited. Relationship of global and sectoral BMO-MRW and pRNFL thickness with corresponding VF parameters and the influence of normalizing BMO-MRW (on BMO circumference, nBMO-MRW) on SF relationships were investigated. Broken-stick models were used to compare the point at which pRNFL and BMO-MRW parameters reached their measurement floor.

Results

The median (interquartile range) of VF mean deviation was −5.9 (−12.6 to −3.6) dB. Spearman correlation coefficients between pRNFL, BMO-MRW, and nBMO-MRW measures and corresponding VF cluster average deviations ranged between 0.55 to 0.80, 0.35 to 0.66, and 0.38 to 0.65, respectively. Bruch's membrane opening–MRW parameters demonstrated weaker SF relationships compared with pRNFL globally and in temporal, temporal-superior, and nasal-inferior sectors (P < 0.03). Normalization of BMO-MRW did not significantly influence SF relationships.

Conclusions

Structure–function relationships were somewhat weaker with BMO-MRW parameters compared with pRNFL in eyes with perimetric glaucoma. Bruch's membrane opening–MRW normalization did not significantly change SF relationships in this group of eyes with mild departures from average BMO size.

Retinal vasculature in glaucoma: a review

Despite the critical impact of glaucoma on global blindness, its aetiology is not fully characterised. Elevated intraocular pressure is highly associated with glaucomatous optic neuropathy. However, visual field loss still progresses in some patients with normal or even low intraocular pressure. Vascular factors have been suggested to play a role in glaucoma development, based on numerous studies showing associations of glaucoma with blood pressure, ocular perfusion pressure, vasospasm, cardiovascular disease and ocular blood flow. As the retinal vasculature is the only part of the human circulation that readily allows non-invasive visualisation of the microcirculation, a number of quantitative retinal vascular parameters measured from retinal photographs using computer software (eg, calibre, fractal dimension, tortuosity and branching angle) are currently being explored for any association with glaucoma and its progression. Several population-based and clinical studies have reported that changes in retinal vasculature (eg, retinal arteriolar narrowing and decreased fractal dimension) are associated with optic nerve damage and glaucoma, supporting the vascular theory of glaucoma pathogenesis. This review summarises recent findings on the relationships between quantitatively measured structural retinal vascular changes with glaucoma and other markers of optic nerve head damage, including retinal nerve fibre layer thickness. Clinical implications, recent new advances in retinal vascular imaging (eg, optical coherence tomography angiography) and future research directions are also discussed.

The Relative Odds of Progressing by Structural and Functional Tests in Glaucoma

PURPOSE

The purpose of this study was to evaluate the effect of disease severity and number of tests acquired during follow-up on the relative odds of identifying progression by structural or functional tests in glaucoma.

METHODS

This was an observational cohort study involving 462 eyes of 305 patients with glaucoma and 62 eyes of 49 healthy subjects. Glaucoma patients and healthy subjects were followed for an average of 3.6 ± 0.9 and 3.8 ± 0.9 years, with a median (interquantile range) of 8 (6-9) and 7 (6-8) visits, respectively. At each visit, subjects underwent visual field assessment with standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) evaluation by spectral-domain optical coherence tomography (SD-OCT). Slopes of change in SAP mean sensitivity and OCT RNFL thickness over time were estimated by linear regression using progressively cumulative visits over time. Cutoff values for age-related expected rates of change for each test were obtained from the healthy group. Progression by SD-OCT and/or SAP was determined if the slope of change was statistically significant and also lower (faster) than the fifth percentile cutoff calculated from the healthy group. A generalized estimating equation logistic regression model was used to evaluate the relative odds of progressing by OCT versus SAP in glaucoma eyes.

RESULTS

Eyes with less severe disease at baseline had a higher chance of being detected as progressing by SD-OCT but not by SAP, whereas an increase in disease severity at baseline increased the chance that the eye would be detected as progressing by SAP but not SD-OCT. Each 1 dB higher MD was associated with a 5% increase in the odds of detecting progression by SD-OCT versus SAP (odds ratio = 1.05 per 1 dB; 95% confidence interval: 1.01-1.09; P = 0.005).

CONCLUSIONS

The ability to detect glaucoma progression by SAP versus SD-OCT is significantly influenced by the stage of disease. Our results may provide useful information for guiding clinicians on the relative utility of these tests for detecting change throughout the disease continuum.

Relationship between Retinal Nerve Fiber Layer Thickness and Hemoglobin Present in the Optic Nerve Head in Glaucoma

Purpose

To observe the relationship between topographic hemoglobin levels in the optic nerve head (ONH), the rim thickness (BMO-MRW), and retinal nerve fiber layer (RNFL) thickness.

Methods

96 normal eyes and 82 glaucomas were examined using TOP strategy (Octopus 300 perimeter), SPECTRALIS OCT, and Laguna ONhE program which estimates hemoglobin from conventional color photographs (Horus Scope DEC 200 fundus camera).

Results

The correlation between Laguna ONhE glaucoma discriminant function (GDF) and SPECTRALIS BMO-MRW was R = 0.81 (P < 0.0001), similar to that between the BMO-MRW and BMO-RNFL thicknesses (R = 0.85, P < 0.0001) (P = 0.227 between both R values). GDF correlated well with RNFL thicknesses in the 360 degrees around the nerve, similar to mean perimetric sensitivity (MS) and BMO-MRW. The amount of hemoglobin in the nasal and temporal sectors showed low correlation with superior and inferior RNFL thicknesses. The superotemporal and inferotemporal sectors located on the vertical diameter of the disk showed good intercorrelation but without a clear RNFL topographic relationship.

Conclusion

GDF showed high correlation with RNFL thickness. Except in the nasal and temporal sectors, ONH hemoglobin correlated well with RNFL thickness.

Relationship between Optical Coherence Tomography Angiography Vessel Density and Severity of Visual Field Loss in Glaucoma

PURPOSE

To evaluate the association between vessel density measurements using optical coherence tomography angiography (OCT-A) and severity of visual field loss in primary open-angle glaucoma.

DESIGN

Observational, cross-sectional study.

PARTICIPANTS

A total of 153 eyes from 31 healthy participants, 48 glaucoma suspects, and 74 glaucoma patients enrolled in the Diagnostic Innovations in Glaucoma Study.

METHODS

All eyes underwent imaging using OCT-A (Angiovue; Optovue, Fremont, CA), spectral-domain OCT (Avanti; Optovue), and standard automated perimetry (SAP). Retinal vasculature information was summarized as vessel density, the percentage of area occupied by flowing blood vessels in the selected region. Two measurements from the retinal nerve fiber layer (RNFL) were used: circumpapillary vessel density (cpVD) (750-μm-wide elliptical annulus around the optic disc) and whole-image vessel density (wiVD) (entire 4.5×4.5-mm scan field).

MAIN OUTCOME MEASURES

Associations between the severity of visual field loss, reported as SAP mean deviation (MD), and OCT-A vessel density.

RESULTS

Compared with glaucoma eyes, normal eyes demonstrated a denser microvascular network within the RNFL. Vessel density was higher in normal eyes followed by glaucoma suspects, mild glaucoma, and moderate to severe glaucoma eyes for wiVD (55.5%, 51.3%, 48.3%, and 41.7%, respectively) and for cpVD (62.8%, 61.0%, 57.5%, 49.6%, respectively) (P < 0.001 for both). The association between SAP MD with cpVD and wiVD was stronger (R² = 0.54 and R² = 0.51, respectively) than the association between SAP MD with RNFL (R² = 0.36) and rim area (R² = 0.19) (P < 0.05 for all). Multivariate regression analysis showed that each 1% decrease in wiVD was associated with 0.66 decibel (dB) loss in MD and each 1% decrease in cpVD was associated with 0.64 dB loss in MD. In addition, the association between vessel density and severity of visual field damage was found to be significant even after controlling for the effect of structural loss.

CONCLUSIONS

Decreased vessel density was significantly associated with the severity of visual field damage independent of the structural loss. Optical coherence tomography angiography is a promising technology in glaucoma management, potentially enhancing the understanding of the role of vasculature in the pathophysiology of the disease.

Structural and Functional Evaluations for the Early Detection of Glaucoma

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection.

The use of Bruch's membrane opening-based optical coherence tomography of the optic nerve head for glaucoma detection in microdiscs

PURPOSE

To assess the performance of Bruch's membrane opening (BMO)-based spectral domain optical coherence tomography (SD-OCT) of the optic nerve head for glaucoma detection in microdiscs in comparison with confocal scanning laser tomography (CSLT).

DESIGN

Retrospective cohort study.

METHODS

82 eyes of 82 patients with disc size <1.63 mm² underwent SD-OCT and CSLT measurements, visual field testing and clinical examination. BMO-based minimal rim width (BMO-MRW), retinal nerve fibre layer thickness (RNFLT) in SD-OCT and rim area measured in CSLT were compared and correlated with visual field defects.

RESULTS

51 patients with glaucoma, 11 patients with ocular hypertension (OHT) and 20 healthy controls had a mean disc area of 1.36±0.19 mm² in CSLT, and BMO area was 1.45±0.22 mm² (r=0.17; p=0.12). In patients with glaucoma, visual field mean defect was -7.5±6.7 dB. Global BMO-MRW correlated better with visual field function (Spearman's r=0.65; p<0.001) than RNFLT (r=0.58; p≤0.001) and CSLT rim area (r=0.47; p=0.004). BMO-MRW significantly deteriorated with progressive visual field loss (p<0.001). In receiver operating characteristic analysis, sensitivity of BMO-MRW was 68.6% at 95% specificity (area under curve (AUC)=0.87), similar to sensitivity of RNFLT (66.4%; AUC=0.81). Performance of CSLT rim area was significantly worse (AUC=0.70, p=0.008). In healthy controls, mean BMO-MRW was 344.3±64.1 µm, mean RNFLT 78.0±11.3 µm and CSLT mean rim area 1.07±0.18 mm².

CONCLUSIONS

In small optic discs, BMO-MRW and peripapillary RNFLT (OCT) have similar sensitivity to discriminate patients with glaucoma from normal controls; both exceed CSLT rim area in diagnostic power. In glaucomatous patients, BMO-MRW correlates strongest with visual field function.

Structure-Function Relationship between Flicker-Defined Form Perimetry and Spectral-Domain Optical Coherence Tomography in Glaucoma Suspects

PURPOSE

To evaluate the relationship between functional parameters of repeated flicker-defined form perimetry (FDF) and structural parameters of spectral-domain optical coherence tomography (SD-OCT) in glaucoma suspects with normal findings in achromatic standard automated perimetry (SAP).

METHODS

Patients with optic nerve heads (ONH) clinically suspicious for glaucoma and normal SAP findings were enrolled in this prospective study. Each participant underwent visual field (VF) testing with FDF perimetry, using the Heidelberg Edge Perimeter (HEP, Heidelberg Engineering, Heidelberg, Germany) at two consecutive visits. Peripapillary RNFL thickness was obtained by SD-OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Correlations and regression analyses of global and sectoral peripapillary RNFL thickness with corresponding global and regional VF sensitivities were investigated.

RESULTS

A consecutive series of 65 study eyes of 36 patients were prospectively included. The second FDF test (HEP II) was used for analysis. Cluster-point based suspicious VF defects were found in 34 eyes (52%). Significant correlations were observed between mean global MD (PSD) of HEP II and SD-OCT-based global peripapillary RNFL thickness (r = 0.380, p = 0.003 for MD and r = -0.516, p < 0.001 for PSD) and RNFL classification scores (R² = 0.157, p = 0.002 for MD and R² = 0.172, p = 0.001 for PSD). Correlations between mean global MD and PSD of HEP II and sectoral peripapillary RNFL thickness and classification scores showed highest correlations between function and structure for the temporal superior and temporal inferior sectors whereas sectoral MD and PSD correlated weaker with sectoral RNFL thickness. Correlations between linear RNFL values and untransformed logarithmic MD values for each segment were less significant than correlations between logarithmic MD values and RNFL thickness.

CONCLUSIONS

In glaucoma suspects with normal SAP, global and sectoral peripapillary RNFL thickness is correlated with sensitivity and VF defects in FDF perimetry.

Enhancement of Visual Field Predictions with Pointwise Exponential Regression (PER) and Pointwise Linear Regression (PLR)

Purpose

The study was conducted to evaluate threshold smoothing algorithms to enhance prediction of the rates of visual field (VF) worsening in glaucoma.

Methods

We studied 798 patients with primary open-angle glaucoma and 6 or more years of follow-up who underwent 8 or more VF examinations. Thresholds at each VF location for the first 4 years or first half of the follow-up time (whichever was greater) were smoothed with clusters defined by the nearest neighbor (NN), Garway-Heath, Glaucoma Hemifield Test (GHT), and weighting by the correlation of rates at all other VF locations. Thresholds were regressed with a pointwise exponential regression (PER) model and a pointwise linear regression (PLR) model. Smaller root mean square error (RMSE) values of the differences between the observed and the predicted thresholds at last two follow-ups indicated better model predictions.

Results

The mean (SD) follow-up times for the smoothing and prediction phase were 5.3 (1.5) and 10.5 (3.9) years. The mean RMSE values for the PER and PLR models were unsmoothed data, 6.09 and 6.55; NN, 3.40 and 3.42; Garway-Heath, 3.47 and 3.48; GHT, 3.57 and 3.74; and correlation of rates, 3.59 and 3.64.

Conclusions

Smoothed VF data predicted better than unsmoothed data. Nearest neighbor provided the best predictions; PER also predicted consistently more accurately than PLR. Smoothing algorithms should be used when forecasting VF results with PER or PLR.

Translational Relevance

The application of smoothing algorithms on VF data can improve forecasting in VF points to assist in treatment decisions.

Optical Coherence Tomography Angiography of the Peripapillary Retina in Glaucoma

IMPORTANCE

Vascular factors may have important roles in the pathophysiology of glaucoma. A practical method for the clinical evaluation of ocular perfusion is needed to improve glaucoma management.

OBJECTIVE

To detect peripapillary retinal perfusion in glaucomatous eyes compared with normal eyes using optical coherence tomography (OCT) angiography.

DESIGN, SETTING, AND PARTICIPANTS

Prospective observational study performed from July 24, 2013, to April 17, 2014. Participants were recruited and tested at Casey Eye Institute, Oregon Health & Science University. In total, 12 glaucomatous eyes and 12 age-matched normal eyes were analyzed. The optic disc region was imaged twice using a 3 × 3-mm scan by a 70-kHz, 840-nm-wavelength spectral OCT system. The split-spectrum amplitude-decorrelation angiography algorithm was used. Peripapillary flow index was calculated as the mean decorrelation value in the peripapillary region, defined as a 700-µm-wide elliptical annulus around the disc. Peripapillary vessel density was the percentage area occupied by vessels. The data statistical analysis was performed from October 30, 2013, to May 30, 2014.

MAIN OUTCOMES AND MEASURES

Variability was assessed by the coefficient of variation. The Mann-Whitney test was used to compare the 2 groups of eyes. Correlations between vascular and visual field variables were assessed by linear regression analysis.

RESULTS

In 12 normal eyes, a dense microvascular network around the disc was visible on OCT angiography. In 12 glaucomatous eyes, this network was visibly attenuated globally and focally. In normal eyes, between-visit reproducibilities of peripapillary flow index and peripapillary vessel density were 4.3% and 2.7% of the coefficient of variation, respectively, while the population variabilities of peripapillary flow index and peripapillary vessel density were 8.2% and 3.0% of the coefficient of variation, respectively. Peripapillary flow index and peripapillary vessel density in glaucomatous eyes were lower than those in normal eyes (P < .001 for both). Peripapillary flow index (Pearson r = -0.808) and peripapillary vessel density (Pearson r = -0.835) were highly correlated with visual field pattern standard deviation in glaucomatous eyes (P = .001 for both). The areas under the receiver operating characteristic curve for normal vs glaucomatous eyes were 0.892 for peripapillary flow index and 0.938 for peripapillary vessel density.

CONCLUSIONS AND RELEVANCE

Using OCT angiography, reduced peripapillary retinal perfusion in glaucomatous eyes can be visualized as focal defects and quantified as peripapillary flow index and peripapillary vessel density, with high repeatability and reproducibility. Quantitative OCT angiography may have value in future studies to determine its potential usefulness in glaucoma evaluation.

Retinal Thickness and the Structure/Function Relationship in the Eyes of Older Adults with Glaucoma

Glaucoma is common and shows high prevalence in older adults. However, there are few studies on the structure/function relationship in older adults with glaucoma. This prospective, cross-sectional study (conducted between February and August 2014), enrolled 102 eyes of 102 subjects aged over 75 years, including 57 eyes with primary open angle glaucoma (POAG), 15 eyes with pseudoexfoliation glaucoma (PXG), and 30 healthy eyes. Multiple regression analysis was used to determine the correlation of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular parameters to mean deviation (MD) to and standard automated perimetry (SAP)-measured sensitivity, assessed with the 30–2 and 10–2 programs. In each 10–2 SAP test point, Spearman’s rank correlation coefficient was used to compare macular retinal nerve fiber layer thickness (mRNFLT), macular ganglion cell-inner plexiform layer thickness (GCIPLT), and mRNFL+GCIPL thickness (GCCT) with sensitivity after adjusting for retinal ganglion cell (RGC) displacement. In eyes with POAG and PXG, cpRNFLT was significantly correlated with 30–2 MD and 30–2 sensitivity. Multiple regression analysis revealed that the POAG had significantly lower cpRNFLT, mRNFLT, GCIPLT, and GCCT according to the severity of disease than control eyes after adjusting for sensitivity, age, sex, and axial length. The PXG eyes had significantly lower cpRNFLT, mRNFLT, and GCCT when compared with the early to moderate POAG eyes. GCCT was significantly correlated with 10–2 sensitivity, except in one juxtafoveal point, (r = 0.338–0.778) in the POAG eyes. The periphery of the central 10° area showed a good correlation between sensitivity and mRNFLT, while the central 5.8° showed a good correlation between sensitivity and GCIPLT. The correlation between structure and function was significant, and objective and quantitative method with OCT assessing glaucoma that does not require patient ability could be a possible parameter to assess diagnosis and progression in older patients with glaucoma.

Retinal nerve fiber layer thickness in prematurity is correlated with stage of retinopathy of prematurity

PURPOSE

To compare retinal nerve fiber layer (RNFL) thickness profiles between preterm and full-term children and to investigate factors affecting the RNFL distribution in preterm children.

METHODS

We performed Spectral domain optical coherence tomography (SD-OCT) peripapillary RNFL circular scan centered on the optic disc in 50 premature and 58 full-term children. RNFL thickness profiles were compared between preterm and full-term children using a linear regression model. Among preterm patients in this study, 20 patients previously received laser treatment for severe retinopathy of prematurity (ROP).

RESULTS

Global average, nasal, and superior disc RNFL thickness profiles were significantly smaller in preterm children (92.70±16.57 μm, 56.02±17.04 μm, and 108.74±27.36 μm, respectively) compared with full-term children (101.63±9.21 μm, P=0.006, 69.14±14.15 μm, P<0.001, and superior, 129.11±18.14 μm, P<0.001, respectively). Multivariable analysis revealed that ROP stage was inversely correlated with nasal RNFL thickness (P=0.010).

CONCLUSIONS

Our SD-OCT data demonstrate decreased global average, nasal, and superior disc RNFL thicknesses in preterm children. ROP stage was inversely correlated with nasal RNFL thickness. Further studies are needed to better understand the association between these structural changes and visual functions in preterm children.

Estimating the Amount of Hemoglobin in the Neuroretinal Rim Using Color Images and OCT

PURPOSE

To calculate the amount of hemoglobin (Hb) in the optic nerve head (ONH), using superimposed color fundus images with disc, rim and cup boundaries obtained by OCT-Cirrus.

MATERIAL AND METHODS

We examined 100 healthy and 121 glaucomatous eyes using Oculus-Spark perimetry, Cirrus-OCT and Visucam (Zeiss) ONH color images. The Laguna ONhE program was then used to calculate the amount of Hb in the cup and six sectors of the rim. Receiver operating characteristic (ROC) analysis was performed and correlations between parameters were calculated.

RESULTS

In suspected and confirmed glaucoma, Hb was significantly lower than controls in all rim sectors, especially the inferior and superonasal (p < 0.0001). Mean deviation (MD) of visual field regions showed greater correlation with the amount of Hb in the superior and inferior sectors of the rim than with rim area (p = 0.02) or nerve fiber layer thickness (p < 0.0001). On ROC analysis, the best diagnostic indicators were OCT rim area, vertical cup/disc ratio (C/D) and Glaucoma Discriminant Function (GDF) of Laguna ONhE, without significant differences.

CONCLUSIONS

The amount of Hb in the ONH seems to have an important relationship with glaucomatous visual field sensitivity. The remaining rim has insufficient perfusion in many cases of glaucoma.

Macular structure-function relationship at various spatial locations in glaucoma

BACKGROUND/AIMS

To study whether the structure-function (S-F) relationship in glaucoma differs according to macular location using spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry 10-2 and 24-2 visual fields (VFs).

METHODS

We enrolled 151 eyes of 151 healthy, preperimetric and perimetric glaucomatous subjects. Macular ganglion cell-inner plexiform layer thicknesses at different parafoveal locations were measured using Cirrus SD-OCT. The mean sensitivity of 10-2 and 24-2 VFs was recorded in the decibel and 1/L scales. The topographic relationships between structure and function were assessed at different parafoveal and hemimacular locations using 'weighted' correlation coefficients. The strength of S-F relationships between macular ganglion cell-inner plexiform layer thickness measurements and VF mean sensitivity in various parafoveal locations and in superior and inferior hemimacula was compared using Steiger's test.

RESULTS

The temporal parafoveal sector showed a significantly greater S-F relationship in each hemimacula compared with other parafoveal sectors (p<0.05). The inferior hemimacula showed a significantly greater S-F relationship than superior hemimacula (p<0.001).

CONCLUSIONS

The strength of the S-F associations at the temporal parafoveal location is significantly greater than that of the central or nasal parafoveal location in each hemimacula. The strength of the S-F association is significantly greater in the inferior hemimacula than in the superior hemimacula.

Glaucoma morphologic damage estimated from functional tests

PURPOSE

To compare direct morphologic measurements with the ones deduced from functional tests.

METHODS

A total of 111 normal eyes (examined twice) and 112 consecutive eyes with suspected or confirmed glaucoma were analyzed using Spark strategy (Oculus Easyfield Perimeter) and Cirrus optical coherence tomography (OCT). The threshold values were used to deduce the thickness of the retinal nerve fiber layer (RNFL) in 25 sectors. They were also used to derive a normalized value of the neuroretinal rim area, correcting the influence of the optic disc area size, and expressing the result as a percentage of their normal average relation.

RESULTS

The correlation between the deduced and the measured RNFL thicknesses were r = 0.77 (p&lt;0.001, standard error [SE] = 15.4 µm in normal and 15.1 µm in glaucomatous eyes) in the sector to sector comparison, and r = 0.80 (p&lt;0.000001, SE = 10.0 µm in normal and 10.4 µm in glaucomatous eyes) for the average thickness. In normal subjects, the SE of deducing a second OCT result from the previous one was 13.2 µm in the sector by sector analysis and 4.6 µm for average thickness. The correlation between the deduced and measured rim area was r = 0.87 (p&lt;0.000001, SE = 6.7% in normal and 15.9% in glaucomatous eyes). Receiver operating characteristic analysis yielded the following areas, sensitivities, and specificities: measured thickness: 0.89, 75.5%, 91.5%; deduced thickness: 0.91, 86.5%, 93.4%; measured rim area: 0.96, 89.2%, 95.3%; deduced rim area: 0.94, 82.9%, 96.2%. Additionally, the results in a new series of 71 normal and 68 glaucomatous eyes are verified.

CONCLUSIONS

Spark perimetry allowed deducing glaucomatous morphologic alterations with significant accuracy.

Use of the structure-function relationship in detecting glaucoma progression in early glaucoma

Background

To evaluate the use of optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness and visual field (VF) measurements in detecting disease progression in patients with early glaucoma.

Methods

Over a 3-year period, this study examined 60 eyes of 39 glaucoma patients whose total deviation in the superior or inferior hemifield was more than -6 dB. All eyes underwent at least four serial RNFL measurements performed by Cirrus OCT, with the first and last measurements separated by at least three years. On the same day as the RNFL imaging, VF testing was also performed by using the Swedish Interactive Threshold Algorithm Standard 30–2 program of the Humphrey Field Analyzer. Serial RNFL thicknesses and VF progression were assessed using the Guided Progression Analysis (GPA) software program. RNFL thickness progression and VF progression were evaluated by the event analysis.

Results

The mean observation period was 57.6 ± 10.0 months, and during this time, a total of 366 OCT and 366 VF measurements were performed. Using only OCT, progression was found in 2 eyes, while progression was found in 1 eye when only using VF GPA. When combined measurement findings were used, the analysis found progression in 8 eyes.

Conclusions

When mild VF defect is present, OCT RNFL thickness measurements can be helpful in discerning glaucoma progression.

Multivariable logistic regression model: a novel mathematical model that predicts visual field sensitivity from macular ganglion cell complex thickness in glaucoma

Purpose

To design a mathematical model that can predict the relationship between the ganglion cell complex (GCC) thickness and visual field sensitivity (VFS) in glaucoma patients.

Design

Retrospective cross-sectional case series.

Method

Within 3 months from VFS measurements by the Humphrey field analyzer 10-2 program, 83 eyes underwent macular GCC thickness measurements by spectral-domain optical coherence tomography (SD-OCT). Data were used to construct a multiple logistic model that depicted the relationship between the explanatory variables (GCC thickness, age, sex, and spherical equivalent of refractive errors) determined by a regression analysis and the mean VFS corresponding to the SD-OCT scanned area. Analyses were performed in half or 8 segmented local areas as well as in whole scanned areas. A simple logistic model that included GCC thickness as the single explanatory variable was also constructed. The ability of the logistic models to depict the real GCC thickness/VFS in SAP distribution was analyzed by the χ² test of goodness-of-fit. The significance of the model effect was analyzed by analysis of variance (ANOVA).

Results

Scatter plots between the GCC thickness and the mean VFS showed sigmoid curves. The χ² test of goodness-of-fit revealed that the multiple logistic models showed a good fit for the real GCC thickness/VFS distribution in all areas except the nasal-inferior-outer area. ANOVA revealed that all of the multiple logistic models significantly predicted the VFS based on the explanatory variables. Although simple logistic models also exhibited significant VFS predictability based on the GCC thickness, the model effect was less than that observed for the multiple logistic models.

Conclusions

The currently proposed logistic models are useful methods for depicting relationships between the explanatory variables, including the GCC thickness, and the mean VFS in glaucoma patients.

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.

Effect of a variability-adjusted algorithm on the efficiency of perimetric testing

PURPOSE

Variability in perimetry increases with the amount of damage, making it difficult for testing algorithms to efficiently converge to the true sensitivity. This study describes a variability-adjusted algorithm (VAA), in which step size increases with variability.

METHODS

Contrasts were transformed to a new scale wherein the SD of frequency-of-seeing curves remains 1 unit for any sensitivity. A Bayesian thresholding procedure based on the existing Zippy Estimation by Sequential Testing (ZEST) algorithm was simulated on this new scale, and results converted back to decibels. The root-mean-squared (RMS) error from true sensitivity based on these simulations was compared against that achieved by ZEST using the same number of presentations. The procedure was repeated after limiting sensitivities to 15 dB or higher, the lower limit of reliable sensitivities using standard white-on-white perimetry in glaucoma, for both algorithms.

RESULTS

When the true sensitivity was 35 dB, with starting estimate also 35 dB, RMS errors of the algorithms were similar, ranging from 1.39 dB to 1.60 dB. When true sensitivity was instead 20 dB, with starting estimate 35 dB, VAA reduced the RMS error from 7.43 dB to 3.66 dB. Limiting sensitivities at 15 dB or higher reduced RMS errors, except when true sensitivity was near 15 dB.

CONCLUSIONS

VAA reduces perimetric variability without increasing test duration in cases in which the starting estimate of sensitivity is too high; for example, due to a small scotoma. Limiting the range of possible sensitivities at 15 dB or higher made algorithms more efficient, unless the true sensitivity was near this limit. This framework provides a new family of test algorithms that may benefit patients.

Correlation of retinal nerve fiber layer thickness and visual fields in glaucoma: a broken stick model

PURPOSE

To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss.

DESIGN

Retrospective cross-sectional study.

METHODS

Eighty-seven healthy and 108 glaucoma subjects (1 eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey Visual Field Analyzer 750i) and spectral-domain optical coherence tomography RNFL scans. Comparison of RNFL thickness values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was used to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point.

RESULTS

The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (P < .001).

CONCLUSIONS

In open-angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable.

A method to estimate the amount of neuroretinal rim tissue in glaucoma: comparison with current methods for measuring rim area

PURPOSE

To test whether the minimum rim area assessed by spectral domain optical coherence tomography (SD-OCT), based on the shortest distance from the Bruch membrane opening (BMO) to the inner limiting membrane, corresponds more closely to retinal nerve fiber layer (RNFL) thickness and visual field mean deviation (MD) than current rim measures in early glaucoma.

DESIGN

Prospective cross-sectional study.

METHODS

We studied 221 participants with non-endstage glaucoma or high-risk ocular hypertension and performed standard automated perimetry. We received SD-OCT and confocal scanning laser ophthalmoscopy (CSLO) scans on the same day. Rim area measured by CSLO was compared with 3 SD-OCT rim measures from radial B-scans: horizontal rim area between BMO and inner limiting membrane within the BMO plane; mean minimum rim width (BMO-MRW); and minimum rim area (BMO-MRA) optimized within sectors and then summed. Correlations between these measures and either MD from perimetry or RNFL thickness from SD-OCT were compared using the Steiger test.

RESULTS

RNFL thickness was better correlated with BMO-MRA (r = 0.676) or BMO-MRW (r = 0.680) than with either CSLO rim area (r = 0.330, P < 0.001) or horizontal rim area (r = 0.482, P < 0.001). MD was better correlated with BMO-MRA (r = 0.534) or BMO-MRW (r = 0.546) than with either CSLO rim area (r = 0.321, P < 0.001) or horizontal rim area (0.403, P < 0.001). The correlation between MD and RNFL thickness was r = 0.646.

CONCLUSIONS

Minimum rim measurements from SD-OCT are significantly better correlated to both RNFL thickness and MD than rim measurements within the BMO plane or based on the clinical disc margin. They provide new structural parameters for both diagnostic and research purposes in glaucoma.

Study of long term structural and functional changes in medically controlled glaucoma

AIM

Prospectively analyze the long term structural and functional changes in patients of primary open angle glaucoma (POAG) receiving medical therapy (beta blockers and non beta blockers). In this study an attempt has been made to evaluate whether medical reduction of IOP prevents or delays the progression of glaucomatous visual field loss and/or optic nerve damage in patients with open angle glaucoma.

METHODS

Study conducted over a period of 27 months, at a tertiary eye care hospital including both eyes of 40 patients with POAG. Group 1 (20 patients, 40 eyes) received beta-blockers, and Group 2 (20 patients, 40 eyes) received non-beta-blockers. Each patient underwent intraocular pressure measurement, best corrected visual acuity, slit-lamp, fundus examination, gonioscopy, central corneal thickness, visual field assessment by Humphrey automated perimetry and retinal nerve fibre layer thickness by Stratus optical coherence tomography at baseline and at two subsequent visits. The average time interval between each visit was 10-11 months. The statistical analysis was done using one-way analysis of variance (ANOVA). Post-hoc test, using tukey' method were adopted. Probablity (P) value of 0.05 or less was considered to be statistically significant.

RESULTS

A total of 80 eyes of 40 patients of POAG were enrolled, 24 males, 16 females, age group 50-80 years. In both beta and non beta blocker group, reduction (improvement) in mean IOP from initial levels to the levels achieved at the 2nd and 3rd visits was statistically significant. One way ANOVA (df=2), fisher f value=11.64, P=0.000, one way ANOVA (df=3), fisher f value=35.61, P=0.000. Both mean deviation (MD) and pattern standard deviation (PSD) in both beta and non beta blockers at different visits were not statistically significant. Retinal nerve fibre layer thickness (RNFL) -only mean inferior retinal nerve fibre layer, the difference between the mean value in beta and non beta blocker groupwere statistically significant. [unpaired t test value (df=78) =2.27, P=0.03]. Side effects with beta blocker were conjunctival hyperemia (10%), burning (5%), and conjunctival hyperemia (5%) in non beta blockers.

CONCLUSION

Non-beta-blockers are as effective as beta-blockers in bringing about a significant lowering of intraocular pressure to the normal range, and in preventing progressive damage to the visual fields and retinal nerve fibre layer. The absence of systemic side effects and superior IOP lowering efficacy has made non beta-blockers attractive for first line therapy for the treatment of glaucoma worldwide.

Combination of optic disc rim area and retinal nerve fiber layer thickness for early glaucoma detection by using spectral domain OCT

BACKGROUND

To compare the diagnostic ability of optic disc rim area (RA), retinal nerve fiber layer thickness (RNFLT), and their combination on sector-based analysis of spectral domain optical coherence tomography (Cirrus OCT) in discriminating subjects with early-stage open angle glaucoma (OAG) from normal subjects.

METHODS

RA and RNFLT of 78 early OAG and 80 normal subjects were measured on Cirrus OCT at the global area, 4 quadrants, 12 clock hours, and 7 + 11 o'clock (a sector that includes 7 and 11 o'clock). A new parameter, RR (a multiplication of the RA and RNFLT) was derived to identify the best combination of the two parameters. Areas under the receiver operating characteristics curves (AUCs) of RA, RNFLT, and RR were compared.

RESULTS

AUCs of RA were larger than those of RNFLT at nasal quadrant, at 1-5 o'clock on Cirrus OCT (all P values < 0.05). At the remaining areas, the two parameters were not significantly different on both devices (all P values > 0.05). RR had significantly larger AUCs than those of both RA and RNFLT at 7 + 11 o'clock (0.931 for RA, 0.933 for RNFLT, and 0.968 for RR) and global area (0.914 for RA, 0.905 for RNFLT, and 0.935 for RR), which were the two areas with largest AUCs.

CONCLUSIONS

RR outperformed both RA and RNFLT of the Cirrus OCT, especially at areas with diagnostic importance. This suggests that combinations of RA and RNFLT by sector-based analysis of Cirrus OCT would be promising to determine early glaucoma.

Correlation between peripapillary retinal nerve fiber layer thickness and fundus autofluorescence in primary open-angle glaucoma

Purpose

To investigate the relationship between retinal nerve fiber layer (RNFL) thickness and retinal pigment epithelium alterations in patients with advanced glaucomatous visual field defects.

Methods

A consecutive, prospective series of 82 study eyes with primary open-angle glaucoma and advanced glaucomatous visual field defects were included in this study. All study participants underwent a full ophthalmic examination followed by visual field testing with standard automated perimetry as well as spectral-domain optical coherence tomography (SD-OCT) for peripapillary RNFL thickness and Optos wide-field fundus autofluorescence (FAF) images. A pattern grid with corresponding locations between functional visual field sectors and structural peripapillary RNFL thickness was aligned to the FAF images at corresponding location. Mean FAF intensity (range: 0 = black and 255 = white) of each evaluated sector (superotemporal, temporal, inferotemporal, inferonasal, nasal, superonasal) was correlated with the corresponding peripapillary RNFL thickness obtained with SD-OCT.

Results

Correlation analyses between sectoral RNFL thickness and standardized FAF intensity in the corresponding topographic retina segments revealed partly significant correlations with correlation coefficients ranging between 0.004 and 0.376 and were statistically significant in the temporal inferior central field (r = 0.324, P = 0.036) and the nasal field (r = 0.376, P = 0.014).

Conclusion

Retinal pigment epithelium abnormalities correlate with corresponding peripapillary RNFL damage, especially in the temporal inferior sector of patients with advanced glaucomatous visual field defects. A further evaluation of FAF as a potential predictive parameter for glaucomatous damage is necessary.

Progressive loss of retinal ganglion cell function precedes structural loss by several years in glaucoma suspects

PURPOSE

We determined the time lag between loss of retinal ganglion cell function and retinal nerve fiber layer (RNFL) thickness.

METHODS

Glaucoma suspects were followed for at least four years. Patients underwent pattern electroretinography (PERG), optical coherence tomography (OCT) of the RNFL, and standard automated perimetry testing at 6-month intervals. Comparisons were made between changes in all testing modalities. To compare PERG and OCT measurements on a normalized scale, we calculated the dynamic range of PERG amplitude and RNFL thickness. The time lag between function and structure was defined as the difference in time-to-criterion loss between PERG amplitude and RNFL thickness.

RESULTS

For PERG (P < 0.001) and RNFL (P = 0.030), there was a statistically significant difference between the slopes corresponding to the lowest baseline PERG amplitude stratum (≤50%) and the reference stratum (>90%). Post hoc comparisons demonstrated highly significant differences between RNFL thicknesses of eyes in the stratum with most severely affected PERG (≤50%) and the two strata with least affected PERG (>70%). Estimates suggested that the PERG amplitude takes 1.9 to 2.5 years to lose 10% of its initial amplitude, whereas the RNFL thickness takes 9.9 to 10.4 years to lose 10% of its initial thickness. Thus, the time lag between PERG amplitude and RNFL thickness to lose 10% of their initial values is on the order of 8 years.

CONCLUSIONS

In patients who are glaucoma suspects, PERG signal anticipates an equivalent loss of OCT signal by several years.