Average Total Deviation Research Articles

The Relationship Between Artificial Intelligence–Assisted OCT Angiography–Derived Foveal Avascular Zone Parameters and Visual-Field Defect Progression in Eyes with Open-Angle Glaucoma

To investigate clinical factors associated with foveal avascular zone (FAZ) parameters obtained using OCT angiography (OCTA) with assistance from a previously developed artificial intelligence (AI) platform in eyes with open-angle glaucoma (OAG). Retrospective longitudinal. This study followed up 885 eyes of 558 patients with OAG for ≥ 2 years; all eyes underwent≥ 5 Humphrey visual-field (VF) tests and had 3.0×3.0 mm macular OCTA scans available. Average total deviation (TD) in the superior, superocentral, inferocentral, and inferior sectors of the Humphrey 24-2 program was calculated. We collected 3.0×3.0 mm macular OCTA images from each patient and used a previously developed AI platform with these images to obtain FAZ parameters, including FAZ area, FAZ circularity index (CI), and FAZ perimeter. Multivariable linear mixed-effects models were used to analyze the relationship between FAZ parameters, TD or TD slope in each quadrant, and systemic factors, adjusting for potential confounding factors, including axial length. Ophthalmic and systemic variables, FAZ parameters, and TD or TD slope in each quadrant. The multivariable model showed that FAZ parameters were correlated with both TD and TD slope in the inferocentral quadrant (β=-0.244 - 0.168, P < 0.001). Both upper-half and lower-half FAZ parameters were better associated with TD-inferocentral and TD-inferocentral slope than TD-superocentral or TD-superocentral slope in terms of β size and statistical significance, indicating that there was no evident vertical anatomical correspondence between TD in the central quadrant and FAZ parameters. Foveal avascular zone area enlargement was associated with female gender (β=0.242, P= 0.003). Loss of FAZ circularity was associated with both aging and comorbid sleep apnea syndrome (SAS) (yes: 1, no: 0) (β=-0.188, P < 0.001; β=-0.261, P= 0.031, respectively). Foveal avascular zone perimeter elongation was associated with aging and female gender (β=0.084, P= 0.040; β=0.168, P= 0.042, respectively). Artificial intelligence-assisted OCTA-measured FAZ enlargement and irregular shape might be good markers ofocular hypoperfusion and associated inferocentral VF defect progression in eyes with OAG. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Archetypal analysis of longitudinal visual fields for idiopathic intracranial hypertension patients presenting in a clinic setting.

We previously applied archetypal analysis (AA) using visual fields (VF) from the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) to derive a model, which quantified patterns (or archetypes [ATs] of VF loss), anticipated recovery, and identified residual VF deficits. We hypothesized that AA could produce similar results using IIH VFs collected in clinical practice. We applied AA to 803 VFs from 235 eyes with IIH from an outpatient neuro-ophthalmology clinic and created a clinic-derived model of ATs, with the relative weight (RW) and average total deviation (TD) for each AT. We also created a combined-derived model from an input dataset containing the clinic VFs and 2862 VFs from the IIHTT. We used both models to decompose clinic VF into ATs of varying percent weight (PW), correlated presentation AT PW with mean deviation (MD), and evaluated final visit VFs considered "normal" by MD ≥ -2.00 dB for residual abnormal ATs. The 14-AT clinic-derived and combined-derived models revealed similar patterns of VF loss previously identified in the IIHTT model. AT1 (a normal pattern) was most prevalent in both models (RW = 51.8% for clinic-derived; 35.4% for combined-derived). Presentation AT1 PW correlated with final visit MD (r = 0.82, p < 0.001 for the clinic-derived model; r = 0.59, p < 0.001 for the combined-derived model). Both models showed ATs with similar patterns of regional VF loss. The most common patterns of VF loss in "normal" final visit VFs using each model were clinic-derived AT2 (mild global depression with enlarged blind spot; 44/125 VFs; 34%) and combined-derived AT2 (near-normal; 93/149 VFs; 62%). AA provides quantitative values for IIH-related patterns of VF loss that can be used to monitor VF changes in a clinic setting. Presentation AT1 PW is associated with the degree of VF recovery. AA identifies residual VF deficits not otherwise indicated by MD.

Investigation of progression pattern and associated risk factors in glaucoma patients with initial paracentral scotomas using Humphrey 10-2

Central visual field (VF) progression could directly threaten patientss visual function compared to glaucomatous damage. This study was designed to investigate visual field (VF) progression pattern and associated risk factors including optical coherence topography angiographic (OCT-A) findings in glaucoma patients with initial paracentral scotoma. This prospective, observational study included 122 eyes presenting as initial paracentral scotomas with serial 24-2 and 10-2 VF tests at the glaucoma clinic of Seoul St Mary's Hospital between November 2017 and August 2020. The participants underwent at least 5 serial VF exams and OCT-A at baseline. Numerical values of the initial and final 10-2 VF tests were averaged for each VF test point using the total deviation map. Innermost 10-2 VF progression was defined as three or more new contiguous points at the central 12 points on 10-2 VF. Other clinical characteristics were collected including history of disc hemorrhage and vessel density (VD) was measured from OCT-A images. Linear regression analysis was performed to obtain the change of mean deviation and a cut-off for progression was defined for both 24-2 and 10-2 VFs. The average total deviation maps of the initial 10-2 VF tests shows initial paracentral scotoma located in the superior region in an arcuate pattern that was deep in the 4°–6° region above fixation. This arcuate pattern was more broadly located in the 4°–10° region in the primary open-angle glaucoma (POAG) group, while it was closer to fixation in 0°–4° region in the normal-tension glaucoma (NTG) group. The final average map shows deepening of scotomas in the 4°–10° region in POAG, which deepened closer to the region of fixation in NTG. The diagnosis of NTG (β 1.892; 95% CI 1.225–2.516; P = 0.035) and lower choroidal VD in the peripapillary atrophy (PPA) region (β 0.985; 95% CI 0.975 to 0.995; P = 0.022) were significantly related to innermost 10-2 VF progression. Initial paracentral scotomas in NTG tended to progress closer to the region of fixation, which should be monitored closely. Important progression risk factors related to paracentral scotoma near the fixation were the diagnosis of NTG and reduced choroidal VD in the β-zone PPA region using OCT-A. We should consider vascular risk factors in NTG patients presenting with initial paracentral scotoma to avoid vision threatening progression of glaucoma.

The Relationship Between Optic Disc and Retinal Artery Position and Glaucomatous Visual Field Progression

PurposeTo investigate whether retinal structural parameters, including positions of the optic disc and major retinal arteries, affect glaucomatous progression of the visual field (VF).MethodsIn this cohort study, 116 eyes of 73 patients with primary open angle glaucoma (POAG) were included. VFs were measured using the Humphrey Field Analyzer 24-2 program and the VF was divided into seven sectors according to the corresponding optic disc angle. Average total deviation (TD) was calculated in each sector. Positions of major retinal arteries in the superotemporal and inferotemporal areas were decided by identifying the points where the retinal artery intersected the 3.4-mm-diameter circle around the optic disc. The relationship between sectorial TD VF progression rate and eight variables (age, mean and standard deviation of intraocular pressure during the observation period, baseline sectorial TD value, papillomacular bundle tilt angle, and axial length, along with superior/inferior arterial angle) was investigated.ResultsThe main outcome measures were the association between retinal structural parameters and glaucomatous progression of VF. The superior retinal artery angular position was positively associated with sectorial TD progression rates in two central sectors in the inferior hemifield, which suggests faster VF progression where superior retinal artery angles are narrow. Papillomacular bundle tilt was not associated with TD progression rate in any sector.ConclusionsProgression of the inferior VF was associated with the superior retinal artery angular position in this study of POAG.

An Artificial Intelligence Approach to Assess Spatial Patterns of Retinal Nerve Fiber Layer Thickness Maps in Glaucoma.

PurposeThe purpose of this study was to classify the spatial patterns of retinal nerve fiber layer thickness (RNFLT) and assess their associations with visual field (VF) loss in glaucoma.MethodsWe used paired reliable 24-2 VFs and optical coherence tomography scans of 691 eyes from 691 patients. The RNFLT maps were used to determine the RNFLT patterns (RPs) by non-negative matrix factorization (NMF). The RPs were correlated with mean deviation (MD), spherical equivalent (SE), and major blood vessel locations. The RPs were further used to predict the 52 total deviation (TD) values by linear regression compared with models using 24 15-degree sectors. Last, we associated the RPs with average TDs of the central upper two locations (C2-TD). Stepwise regression was applied to remove redundant features.ResultsNMF highlighted 16 distinct RPs. Twelve RPs had arcuate-like informative zones (iZones): six with superior iZones, five with inferior iZones, and one RP with a bi-hemifield iZone, and four with non-arcuate-like temporal or nasal iZones. Twelve, nine, nine, and nine RPs were significantly (P < 0.05) correlated to MD, SE, and superior and inferior artery locations, respectively. Using RPs significantly (P < 0.05) improved the prediction of 52 TDs compared with using 24 15-degree sectors. Using RPs significantly (P < 0.001) improved the C2-TD prediction related to thinning in the inferior vulnerability zone compared with using the 24 sectoral RNFLTs.ConclusionsUsing RPs improved the VF prediction compared with using sectoral RNFLTs.Translational RelevanceThe RPs characterizing both pathological and anatomical variations can potentially assist clinicians better assess RNFLT loss.

The Relationship Between Intraocular Pressure and Rates of Central Versus Peripheral Visual Field Progression.

In this longitudinal prospective cohort study of open-angle glaucoma patients, intraocular pressure (IOP) parameters (mean, fluctuation, and maximum) had a similar effect on glaucomatous progression in the central and peripheral visual field (VF) regions. To study the effects of IOP on rates of glaucomatous central versus peripheral VF progression. The African Descent and Glaucoma Evaluation Study (ADAGES) is a longitudinal prospective cohort study that recruited patients from 3 centers. A sample of those with established glaucoma were included in this study. The mean peripheral sensitivity (MPS) and the mean central sensitivity (MCS) were defined based upon the average total deviation of the peripheral and central (10 degrees) points of the 24-2 VF, respectively. Progression was based upon central and peripheral change from linear mixed-effects models. The relationships between VF progression and IOP mean, maximum, and fluctuation as continuous variables were also investigated. Main outcome measures were MPS and MCS progression rates. A total of 452 eyes of 344 patients were studied. The mean number of VFs (SD) for each eye was 13.3 (6.4) over 9.1 (3.7) years. The mean baseline MD was -5.1 (3.9) dB and the mean rate of MD change was -0.26 dB/y [95% confidence interval (CI): -0.33 to -0.20, P<0.001]. Mean rates of MPS (-0.27 dB/y, 95% CI: -0.33 to -0.22, P<0.001) and MCS change (-0.26 dB/y, 95% CI: -0.31 to -0.21, P<0.001) were similar (P=0.351). Mean, fluctuation, and maximum IOP were significantly associated with MPS and MCS (all P<0.025). The effect of IOP parameters on VF progression was statistically similar between central and peripheral VF regions.

The optic nerve head vasoreactive response to systemic hyperoxia and visual field defect progression in open-angle glaucoma, a pilot study.

To investigate the effect of optic nerve head (ONH) tissue vasoreactivity on glaucoma visual field defect progression. This prospective, longitudinal study comprised 28 eyes of 16 patients with open-angle glaucoma. Baseline data were obtained from oxygen inhalation testing, including laser speckle flowgraphy measurements of tissue-area mean blur rate (MT), which represents ONH tissue blood flow, and the mean percentage change in MT (MT-change). Follow-up data were collected for at least 2years, including at least 5 reliable visual field tests. The average total deviation (TD) was calculated in each sector of the Garway-Heath map; in this study, superior, central and inferior TD corresponded to inferior, temporal and superior MT or MT-change, respectively. MT and MT-change in three sectors per eye were included as explanatory variables in a multivariable linear mixed-effects model, with TD slope set as the response variable. At baseline, lower MT and higher diastolic blood pressure were associated with lower MT-change (p<0.05). Additionally, MT-change significantly contributed to TD slope in the corresponding sectors (β=0.41, p=0.01). Weaker ONH tissue vasoreactivity to systemic hyperoxia, assessed with laser speckle flowgraphy, was associated with lower baseline ONH tissue blood flow, higher diastolic blood pressure and rapid visual field defect progression. Laser speckle flowgraphy variables during oxygen provocation testing may represent potentially useful predictive biomarkers of glaucoma progression.

Sectoral Differences in the Association of Optic Nerve Head Blood Flow and Glaucomatous Visual Field Defect Severity and Progression.

To investigate sectoral differences in the relationship between optic nerve head tissue blood flow, anatomically corresponding visual field defect severity, and future progression. This retrospective longitudinal medical chart review comprised 508 eyes of 319 open-angle glaucoma patients (mean deviation: -9.2 ± 7.0 dB), followed for an average of 4.7 ± 1.1 years; an average 11.7 ± 3.7 visual field tests were performed. Average total deviation (TD) was calculated in the superior, central, and inferior sectors of the Humphrey 24-2 program. The optic nerve head was divided to obtain inferior, temporal, and superior tissue-area mean blur rate (MT), derived from laser speckle flowgraphy. At baseline, the correlation between MT and TD was compared in anatomically corresponding sectors. We performed a multivariate analysis to determine the contribution of baseline MT to corresponding TD slope and to determine background factors influencing superior to temporal MT. We used a linear-mixed effect model for the statistical analysis. At baseline, the highest β coefficients were found between MT-superior and TD-inferior, MT-temporal and TD-central, and between MT-inferior and TD-superior, in that order (β = 0.38, β = 0.27, β = 0.26, respectively). MT-superior and MT-temporal independently contributed to corresponding TD slope (P < 0.05). Male sex, high body mass index, and the prevalence of sleep apnea syndrome were contributing factors to lower superior to temporal MT (P < 0.05). Review of medical history, measurements of systemic variables, and laser speckle flowgraphy parameters might help clinicians to predict visual field defect severity and progression.

Factors Related to Superior and Inferior Hemifield Defects in Primary Open-Angle Glaucoma.

Purpose We aimed to investigate factors related to superior and inferior hemifield defects in primary open-angle glaucoma (POAG). Methods Sixty-seven subjects with newly diagnosed, untreated POAG underwent optical coherence tomography (OCT) of the disc area, macular ganglion cell complex (mGCC), and circumpapillary retinal nerve fiber layer (cpRNFL) thickness within 6 months of the visual field (VF) test. Based on the VF and OCT results, 40 subjects had a superior and 27 an inferior hemifield defect. Clinical data including visual acuity, refractive error, disc hemorrhage, VF indexes, and medical history were recorded. Results Average mGCC thickness corresponding to the defective hemifields was thinner in the superior VF defect group than in the inferior VF defect group (P=0.003). Average total deviation (TD) was comparable between the two groups. However, the superior VF defect group had a higher prevalence of defects (P=0.001) and lower TD (P=0.002) within central 5 degrees of VF than the inferior VF defect group. In multivariate regression analyses, the temporal-lower and inferior-temporal cpRNFL thicknesses were significant contributing factors to the inferior mGCC thickness in the superior VF defect group. In the inferior VF defect group, the disc area, family history of glaucoma, and temporal-upper cpRNFL thickness contributed to the superior mGCC thickness. Conclusion The inferior mGCC thickness corresponding to the superior hemifield defect group was significantly thinner than the superior mGCC thickness corresponding to the inferior hemifield defect group. The factors related to the reduction of the corresponding mGCC thickness may differ between superior VF defect and inferior VF defect groups.

Comparison of visual field tests in glaucoma patients with a central visual field defect

ObjectiveTo compare the 24-2 and 10-2 visual fields (VFs) and investigate the degree of differences between the 2 tests in glaucomatous eyes with central VF defects. DesignRetrospective study. ParticipantsIn all, 99 eyes of 99 glaucoma patients who underwent both the 24-2 VF and 10-2 VF tests within 6 months were enrolled. MethodsGlaucomatous eyes with damage involving a central VF defect were divided into 3 groups based on the average total deviation (TD) of 12 central points in the 24-2 VF test. The TD difference was calculated by subtracting the average TD of the 10-2 VF test from the average TD of 12 central points in the 24-2 VF test. The absolute central TD difference in each quadrant was defined as the absolute value of the TD value obtained by subtracting the average TD of 4 central points in the 10-2 VF test from the innermost TD in the 24-2 VF test in each quadrant. ResultsThe TD differences differed significantly between the severe group and the early and moderate groups ( p < 0.001). In the superonasal quadrant, the absolute central TD difference was significantly greater in the moderate group than in the early group ( p < 0.05). In the superotemporal quadrant, the absolute central TD difference was significantly greater in the severe group than in the other 2 groups ( p < 0.001). ConclusionsOur results indicate that the results of VF tests for different VFs can be inconsistent, depending on the degree of central defects and the VF quadrant.

Predicting Future Self-Reported Motor Vehicle Collisions in Subjects with Primary Open-Angle Glaucoma Using the Penalized Support Vector Machine Method.

PurposeWe predict the likelihood of a future motor vehicle collision (MVC) from visual function data, attitudes to driving, and past MVC history using the penalized support vector machine (pSVM) in subjects with primary open-angle glaucoma (POAG).MethodsPatients with POAG were screened prospectively for eligibility and 185 were analyzed in this study. Self-reported MVCs of all participants were recorded for 3 years from the baseline using a survey questionnaire every 12 months. A binocular integrated visual field (IVF) was calculated for each patient by merging a patient's monocular Humphrey Field Analyzer (HFA) visual fields (VFs). The IVF was divided into six regions, based on eccentricity and the right or left hemifield, and the average of the total deviation (TD) values in each of these six areas was calculated. Then, the future MVCs were predicted using various variables, including age, sex, 63 variables of 52 TD values, mean of the TD values, visual acuities (VAs), six sector average TDs with (predpenSVM_all) and without (predpenSVM_basic) the attitudes in driving, and also past MVC history, using the pSVM method, applying the leave-one-out cross validation.ResultsThe relationship between predpenSVM_basic and the future MVC approached significance (odds ratio = 1.15, [0.99–1.29], P = 0.064, logistic regression). A significant relationship was observed between predpenSVM_all and the future MVC (odds ratio = 1.21, P = 0.0015).ConclusionsIt was useful to predict future MVCs in patients with POAG using visual function metrics, patients' attitudes to driving, and past MVC history, using the pSVM.Translational RelevanceCareful consideration is needed when predicting future MVCs in POAG patients using visual function, and without driving attitude and MVC history.

Association between Optic Nerve Head Microcirculation and Macular Ganglion Cell Complex Thickness in Eyes with Untreated Normal Tension Glaucoma and a Hemifield Defect.

Purpose. We evaluated the association between optic nerve head (ONH) microcirculation and macular ganglion cell complex (mGCC) thickness in patients with untreated normal tension glaucoma (NTG) and a hemifield defect. Methods. The medical records of 47 patients with untreated NTG were retrospectively reviewed. Laser speckle flowgraphy was used to obtain mean blur rate (MBR), a relative measure of blood flow. Average total deviation (TD), mGCC, and the circumpapillary retinal nerve fiber layer (cpRNFL) thickness were also analyzed. Results. All parameters corresponding to the defective hemifield were significantly lower than those corresponding to the normal hemifield. In the defective hemifield, MBR was correlated with TD, mGCC, and cpRNFL thickness. In the normal hemifield, MBR was only correlated with mGCC thickness, and multiple regression analysis showed that mGCC thickness was a significant contributing factor of the MBR. Conclusion. MBR was well correlated with mGCC thickness in eyes with untreated NTG and a hemifield defect. In the normal hemifield, mGCC thickness was a contributing factor of the MBR indicating that ONH circulatory dysfunction may be associated with retinal structural changes in the early stages of glaucoma. A reduction in ONH microcirculation may be an early indicator of the presence and progression of glaucoma.

Investigating the Influence of Visual Function and Systemic Risk Factors on Falls and Injurious Falls in Glaucoma Using the Structural Equation Modeling.

PurposeTo investigate the relationship between visual function and the risks of falling and injurious falls in subjects with primary open angle glaucoma (POAG)MethodsQuestionnaires were conducted in 365 POAG patients to assess history of falls and falls with injury and general patient health. Structural equation modeling (SEM) was used to investigate the relationship between visual function, as measured by a patient’s binocular integrated visual field and visual acuity (VA), general health and the risks of falling and injurious falls.ResultsAmong the 365 subjects, 55 subjects experienced falls in the past year. A significant difference was observed in worse-eye VA between the faller and non-faller groups (p = 0.03). SEM of fallers obtained a Root Mean Square Error of Approximation (RMSEA) of 0.035 and a Comparative Fit Index (CFI) of 0.99. The 95% confidence intervals (CI) of regression coefficients from this model suggested better VA and worse VA were significant risk factors for falling. Among the 55 fallers, 22 subjects experienced an associated injury. There was a significant difference in gender between the non-injurious and injurious faller groups (p = 0.002). SEM of injurious fallers obtained a RMSEA of 0.074 and a CFI of 0.97. In this SEM model, the 95% CI of regression coefficients suggested gender and average total deviation values in the lower peripheral visual field were significant risk factors for an injurious fall.ConclusionsThis study suggests that worse-eye and better-eye VAs are associated with falls. Furthermore, patients with inferior visual field loss and females were found to be at greater risk of injurious falls.

Prevalence and Nature of Early Glaucomatous Defects in the Central 10° of the Visual Field

The macula is essential for visual functioning and is known to be affected even in early glaucoma. However, little is currently understood about the prevalence and nature of central vision loss in early glaucoma. To determine the prevalence and characteristics of visual field (VF) defects in the central 10° in glaucoma suspects and patients with mild glaucoma using a prospective design. This prospective observational cohort study was conducted at an outpatient glaucoma specialty clinic. One hundred eyes from 74 patients with glaucomatous optic neuropathy and a 24-2 VF with mean deviation better than -6 dB were prospectively studied and tested with a 10-2 test. Reliable: VF hemifields were classified as abnormal based on a cluster criterion, and abnormal 10-2 VFs were categorized based on the pattern of abnormal points: arcuatelike, widespread, or other. In addition, at each point of the 10-2 VF, the total deviation values were averaged across eyes and the number of abnormal points with total deviation values below a specific criterion level were calculated. RESULTS There appeared to be as many abnormal 10-2 hemifields (53%) as abnormal 24-2 hemifields (59%). Of the eyes with normal 24-2 hemifields, 16% were classified as abnormal when the 10-2 test was used. Of the abnormal 10-2 hemifields, 68%, 8%, and 25% were arcuatelike, widespread, and other, respectively. The average total deviation values and number of abnormal points plots revealed superior VF defects that were deeper and closer to fixation than those in the inferior VF. The 10-2 VF was abnormal in nearly as many hemifields as was the 24-2 VF, including some with normal 24-2 VF, suggesting that the 24-2 test is not optimal for detecting early damage of the macula. The pattern of the defects was in agreement with a recent model of macular damage.

Correlation of magnetic resonance imaging optic nerve parameters to optical coherence tomography and the visual field in glaucoma

To determine the viability of using magnetic resonance imaging measurement of optic nerve morphology as an objective analysis of glaucomatous damage. Retrospective study conducted at Tohoku University Hospital. Thirty-eight eyes of 19 patients with open-angle glaucoma. Patients were scanned with T2-weighted and 3-T diffusion tensor magnetic resonance imaging, and parameters of the optic nerve, including fractional anisotropy, apparent diffusion coefficient and cross-sectional area, were determined. Conventional parameters of glaucomatous damage, including circumpapillary and macular retinal nerve fibre layer thickness, and mean deviation and average total deviation of the central 16 test points from the Humphrey Field Analyzer, were then compared with the magnetic resonance imaging-derived parameters. Spearman's coefficient of correlation was calculated to determine the significance of the correlation. Correlation coefficient between the magnetic resonance imaging parameters and the parameters of glaucomatous damage. Mean deviation was significantly correlated with all magnetic resonance imaging parameters (fractional anisotropy: r = 0.53, apparent diffusion coefficient: r = -0.44, cross-sectional area: r = 0.70). Circumpapillary retinal nerve fibre layer thickness was significantly correlated with fractional anisotropy (r = 0.60) and cross-sectional area (r = 0.47), but not apparent diffusion coefficient (r = -0.29). Central macular function and macular retinal nerve fibre layer thickness were also significantly correlated with magnetic resonance imaging parameters. Optic nerve magnetic resonance imaging parameters were significantly correlated to glaucomatous damage. Magnetic resonance imaging analysis of the optic nerve may, thus, have value as an objective instrument to assess glaucomatous degeneration, including the function of the macula.

Correlation Between Retinal Nerve Fiber Layer Thickness and Visual Field Sensitivity: Diffuse Atrophy Imaging Study

To identify the correlation between retinal nerve fiber layer (RNFL) thickness and visual field sensitivity in healthy eyes with preperimetric and perimetric glaucoma and to estimate the functional RNFL loss in eyes with pre-perimetric glaucoma. One hundred and two eyes with glaucoma and diffuse RNFL atrophy and 102 healthy eyes were enrolled. The correlation between optical coherence tomography (OCT)-measured RNFL thickness of the superior (clock-hour segments 10, 11, 12, 1, 2, and 3) and inferior (clock-hour segments 5, 6, 7, and 8) area and the average total deviations of the inferior and superior hemifields in standard automated perimetry (SAP) were evaluated using the simple linear model, respectively. The OCT-measured RNFL thickness was assumed to comprise functional and residual thicknesses; the residual thickness was calculated from the simple linear model and the eyes with severe diffuse RNFL atrophy. Functional RNFL thickness was compared between groups. Twenty-seven eyes had preperimetric and 75 eyes had perimetric glaucoma. The coefficient of determination (R(2)) of the simple linear model was 0.71 to 0.77 for the correlation between RNFL thickness and total deviation of SAP. The estimated residual thickness was 50.4 to 56.5 μm. On comparison with normal eyes, eyes with preperimetric glaucoma were estimated to have 37% to 41% functional RNFL loss. The correlation between RNFL thickness and SAP sensitivity was well explained by the simple linear model. Approximately 40% loss of the functional RNFL was found in preperimetric glaucoma.

Receiver-operating characteristic analysis of multifocal VEPs to diagnose and quantify glaucomatous functional damage

To test whether multifocal visual evoked potential (mfVEP) recording using two perpendicularly placed channels, as previously reported, to measure the degree of signal-to-noise ratio (SNR) distribution overlap between a signal window and a noise window would efficiently detect and quantify glaucomatous damage. Humphrey visual field (HVF) and mfVEP were recorded from 56 patients with primary open-angle glaucoma and mean deviation less than -15 dB and 62 age-matched ophthalmologically normal individuals. Areas under the receiver-operating characteristic curve (SNR-AUC) were calculated based on the proportion of mfVEP responses that exceeded a specific SNR criterion for both windows. Abnormal sectors with an SNR deviated from the previously established norm with P<5% and 1% were counted. Diagnostic accuracy of the SNR-AUC was similar to that of the average total deviation (TD) of the HVF. The hemifield agreement to detect a defect in mfVEP and HVF was 77.1-87.3%, which was similar to previous reports using multiple channels. Correlation coefficients between SNR-AUC and average TD (0.74 in the upper hemifield and 0.65 in the lower) were significantly higher than those between the sums of abnormal locations on the mfVEP and HVF probability plots (0.27 and 0.33, respectively). Two perpendicular channels can detect and quantify functional damage due to glaucoma. The SNR-AUC may be used as a global index to quantify diffuse glaucomatous functional loss.

SU‐E‐T‐155: Evaluation of An in Vivo Device for Daily Patient Treatment Delivery Measurements Using a Varian Linear Accelerator

Purpose: A clinical evaluation of a commercially available dosimetric device for in‐vivo monitoring of IMRT and VMAT treatments. Methods: The Device for Advanced Verification of IMRT Deliveries (DAVID) system (PTW, Freiburg, Germany) is a transparent multi‐wire harp chamber that can slide into the wedge slot of a Varian linear accelerator. Its 40 measurement wires correspond to the positions of the leaf pairs of a Millennium‐80 MLC, with a projected spacing at isocenter of 5 mm. The DAVID was inserted into the beam during deliveries of clinically approved IMRT and VMAT treatments. The ability of the DAVID to detect errors in MLC positions was tested by introducing small errors into the plans. The reproducibility of measurements was tested for several disease sites over a series of deliveries. Results: The reproducibility of IMRT and VMAT plans is good. The maximum deviation of any one leaf among all plans and all deliveries was 3.11% (IMRT) and −2.09% (VMAT). The maximum total deviation among all plans and all deliveries was 3.41% (IMRT) and −1.99% (VMAT). The average total deviation among all plans and all deliveries for IMRT was 1.35% ± 1.06% and for VMAT was 0.40% ± 1.35%. When intentional errors were introduced, the DAVID could consistently detect leaf position errors when the resulting gap differed from the plan by great than or equal to 1 mm. Conclusions: The DAVID system is a useful, reliable tool for daily in‐vivo monitoring of patient treatments. It is capable of detecting errors as small as 1 mm, and requires no additional time or effort by the treatment staff for data collection. The DAVID system can provide assurance that every fraction of an IMRT or VMAT treatment is being executed as planned.This work partially supported by PTW (Freiburg, Germany).

Visual field loss in patients with normal-tension glaucoma under topical nipradilol or timolol: Subgroup and subfield analyses of the nipradilol-timolol study

To estimate the deterioration rates of visual field loss in Japanese normal-tension glaucoma (NTG) patients under either topical nipradilol or timolol, and to explore intergroup differences in the treatment results. A total of 146 NTG patients with mild to moderate damage were randomized to either nipradilol or timolol and followed for 3 years with a periodic comprehensive ophthalmological visual field examination (30-2 Humphrey perimeter program) every 6 months (the Nipradilol-Timolol Study). The time course of mean deviation (MD), the average total deviation (TD(mean)) in four subfields, and the corrected pattern standard deviation (CPSD) were compared between the two groups using regression analysis with a linear mixed effect model. The estimated slope for MD (dB/year) was -0.03 in the nipradilol and -0.05 in the timolol group (P > 0.4). In both groups, TD(mean) in the superior-central subfield and CPSD showed significant changes (-0.3 and 0.2-0.3, P <or= 0.001). In the patients with early visual field loss or those younger than 40 years, deterioration of some visual field parameters tended to be slower in the nipradilol group than in the timolol group. During 3 years of monotherapy with either nipradilol or timolol in NTG patients, only TD(mean) in the superior-central subfield and the CPSD changed significantly without any intergroup differences.

Retinal Nerve Fiber Structure versus Visual Field Function in Patients with Ischemic Optic Neuropathy: A Test of a Linear Model

To test a linear model relating the regional loss in retinal nerve fiber (RNFL) thickness to the corresponding regional loss in sensitivity with data from patients with previous anterior ischemic optic neuropathy (AION). Case-control study. Twenty-four individuals with AION and 20 with normal vision were tested. The time since the AION attack ranged from 5.2 months to more than 20.3 years (median, 2.95 years). Eyes were tested with standard automated perimetry (SAP) and with optical coherence tomography (OCT), both RNFL thickness scans. The average RNFL thickness of the inferior and superior disc sectors was plotted against the average total deviations (linear units) of the corresponding superior and inferior arcuate field regions, and a linear model was fitted. According to the model, the RNFL thickness R=s(o)T+b, (1), where T is the relative SAP sensitivity loss (on a linear scale; e.g., for -3 dB, T = 0.5), s(o) is the RNFL thickness attributable to axons in the healthy or normal state (T = 1.0), and b is the residual RNFL measured when all sensitivity and axons are lost. Optical coherence tomography RNFL thickness and SAP sensitivity. The data from the AION patients resembled the data from glaucoma patients previously tested and were described by the linear model. For patients with SAP losses of more than -10 dB in the arcuate region, the RNFL thickness provided an estimate of residual RNFL thickness, b. The median value of b (45.5 microm) was similar to the value for patients with glaucoma. It varied among individuals (range, 30.4-63.3 microm), showing a very weak correlation with patient's age (r = 0.30) and the time since the AION episode (r = 0.26), but an excellent correlation (r(2) = 0.94; P<0.01) with the value of s(o), estimated from the unaffected eyes. The relationship between a structure (OCT RNFL thickness) and function (SAP sensitivity loss) is the same for patients with AION and glaucoma and can be approximated by a simple linear model. The model may provide a framework for identifying those patients with ganglion cell axons that are malfunctioning but are alive.