Linear discriminant score for differentiating early primary open angle glaucoma from glaucoma suspects

Purpose: To determine the diagnostic accuracy of a linear discriminant function (LDF) based on macular ganglion cell complex (GCC), optic nerve head (ONH) and retinal nerve fibre layer (RNFL) for differentiating early primary open-angle glaucoma (POAG) from glaucoma suspects. Methods: In this cross-sectional study, data from consecutive 127 glaucoma suspects and 74 early POAG eyes were analysed. Each patient underwent detailed ocular examination, standard automated perimetry, GCC and ONH and RNFL analysis. After adjusting for age, gender and signal strength using the analysis of covariance; Benjamin–Hochberg multiple testing correction was performed to detect truly significant parameters to calculate the LDF. Subsequently, diagnostic accuracy of GCC and ONH and RNFL were determined. The obtained LDF score was evaluated for diagnostic accuracy in another test set of 32 suspect and 19 glaucomatous eyes. Data were analysed with the R-3.2.1 (R Core Team 2015), analysis of variance, t-test, Chi-square test and receiver operating curve. Results: Among all GCC parameters, infero temporal had the best discriminating power and average RNFL thickness and vertical CDR among ONH and RNFL parameters. LDF scores for GCC had AUROC of 0.809 for a cut-off value 0.07, while scores for ONH and RNFL had AUROC of 0.903 for a cut-off value ? 0.24. Analysis on combined parametric space resulted in avg RNFL thickness, vertical CDR, min GCC + IPL and superior GCC + IPL as key parameters. LDF scores obtained had AUROC of 0.924 for a cut-off value 0.1. The LDF was applied to a test set with an accuracy of 84.31%. Conclusion: The LDF had a better accuracy than individual GCC and ONH and RNFL parameters and can be used for diagnosis of glaucoma.

The Effectiveness of Visual Field C10-2 in the Early Detection of Glaucoma with Parafoveal Scotoma

PURPOSE: To identify the correspondence between the central sensitivity of several visual field (VF) tests and ganglion cell inner plexiform layer (GC-IPL) thickness in early glaucoma patients with parafoveal scotoma. METHODS: Fifty-seven eyes from 57 patients with glaucomatous optic neuropathy and parafoveal scotoma were analyzed using the standard automated perimetry (SAP) C10-2 test, the SAP C24-2 test, and the frequency doubling technology perimetry (FDT) C24-2 test. The correlation between the VF central sensitivity and the GC-IPL thickness from macular scans via optical coherence tomography was analyzed. RESULTS: The central sensitivity was 27.51 ± 5.43 dB, 27.39 ± 5.05 dB, and 22.09 ± 5.08 dB for SAP C24-2, SAP C10-2, and FDT C24-2, respectively. Mean GC-IPL thickness was 70.2 ± 8.5 µm. Using regression analysis, the value of log R² between the logarithmic central sensitivity and GC-IPL thickness was 0.498, and the linear R2 between the antilogarithmic central sensitivity and GC-IPL thickness in SAP C10-2 was 0.486, and both were statistically significant (p < 0.05). This relationship was stronger in early glaucoma patients compared to late glaucoma patients using SAP C10-2. CONCLUSIONS: The structure-function relationship between GC-IPL thickness and central sensitivity was better with SAP C10-2, especially in early glaucoma patients, compared to other VF modalities.

Significance of visual electrophysiological techniques in the early diagnosis of glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

Glaucoma is a group of diseases which can threaten and damage the optic nerve and its visual pathway, leading to visual impairment as a result. Glaucomatous optic neuropathy is a chronic disease accompanied by apoptosis of retinal ganglion cells ( RGCs ) , visual field defect and cupping of optic nerve head. The gold standard in functional glaucoma evaluation is standard automated perimetry ( SAP) , but it is often limited to the subjective feelings of the patients. Still, visual electrophysiological techniques cannot replace the conventional inspection, but with its rapid development, it has provided a new strategy for the early diagnosis of glaucoma as a supplement because it can show changes in amplitude and latency before visual field defect. Here we review three special electroretinograms and multifocal focal visually evoked potentials in the early diagnosis of glaucoma.

Ability of spectral domain optical coherence tomography peripapillary retinal nerve fiber layer thickness measurements to identify early glaucoma.

Purpose: To evaluate the ability of spectral domain optical coherence tomography (OCT) peripapillary retinal nerve fiber layer thickness (RNFLT) parameters to distinguish normal eyes from those with early glaucoma in Asian Indian eyes. Design: Observational cross-sectional study. Materials and Methods: One hundred and seventy eight eyes (83 glaucoma patients and 95 age matched healthy subjects) of subjects more than 40 years of age were included in the study. All subjects underwent RNFLT measurement with spectral OCT/ scanning laser ophthalmoscope (SLO) after dilatation. Sensitivity, specificity and area under the receiving operating characteristic curve (AROC) were calculated for various OCT peripapillary RNFL parameters. Results: The mean RNFLT in healthy subjects and patients with early glaucoma were 105.7 ± 5.1 μm and 90.7 ± 7.5 μm, respectively. The largest AROC was found for 12 o’clock- hour (0.98), average (0.96) and superior quadrant RNFLT (0.9). When target specificity was set at ≥ 90% and ≥ 80%, the parameters with highest sensitivity were 12 o’clock -hour (91.6%), average RNFLT (85.3%) and 12 o’ clock- hour (96.8 %), average RNFLT (94.7%) respectively. Conclusion: Our study showed good ability of spectral OCT/ SLO to differentiate normal eyes from patients with early glaucoma and hence it may serve as an useful adjunct for early diagnosis of glaucoma.

Retinal Nerve Fiber Layer Thickness Analysis in Early Glaucoma

PURPOSE: To investigate the difference between superior and inferior peripapillary retinal nerve fiber layer (RNFL) thickness in early glaucoma patients who have RNFL defect in either superior quadrant or inferior quadrant and to determine if it can be useful to detect early glaucomatous change. METHODS: Eighty eight patients with early glaucoma who have RNFL defect in either the superior quadrant or the inferior quadrant as confirmed by red free photograph (40 eyes with normal standard automated perimetry and 48 eyes with early glaucomatous visual field loss) were divided into the superior RNFL defect group and the inferior RNFL defect group. The average RNFL thickness was measured in the superior and inferior quadrants using optical coherence tomography and the thickness differences between the superior and the inferior quadrants (S-I difference) were compared among early glaucoma eyes and 59 normal controls. Then, discriminative power of the S-I difference was assessed by area under ROC (AUROC). RESULTS: The average thickness of the RNFL showed a statistically significant difference between early glaucoma eyes and normal controls (P<0.05). S-I differences of the superior RNFL defect group and inferior RNFL defect group in preperimetric patients and in early perimetric patients were -20.5+/-16.4 micrometer and 15.0+/-14.2 micrometer, -24.0+/-17.2 micrometer and 18.4+/-16.7 micrometer, respectively, which were significantly greater than that of the normal control group (-8.2+/-17.1 micrometer). AUROC of S-I difference in the superior and inferior defect groups of preperimetric patients were 0.691, 0.872, respectively. CONCLUSIONS: The difference in RNFL thickness between the superior and inferior quadrants (S-I difference) in early glaucoma patients was larger than in normal controls. We expect that this parameter of RNFL analysis using OCT can be useful in detecting early glaucoma.

Change in Optic Nerve Head Topography in Progression of Early Glaucoma

PURPOSE: To investigate the clinical manifestation and the structural optic disc changes according to the development of reproducible visual field defects in a group of preperimetric patients converting to early glaucoma. METHODS: Standard automated perimetry (Humphrey Field Analyzer) was performed every six months in 294 preperimetric patients. Each subject was classified as either converter or non-converter according to glaucomatous visual field changes, and the clinical manifestations were analyzed retrospectively. Sequential optic disc images were obtained using the TopSS scanning laser ophthalmoscope (TopSS(TM)) and optic disc parameters were measured to determine if any change had occurred. RESULTS: A total of 44 eyes from 44 subjects (14.9%) in 294 patients subsequently developed early glaucomatous field loss (converters). The progression rate of visual field defect is 0.43dB/year. In respect to age, sex, refractive error, and diabetes mellitus, no significant differences were observed. Elevated IOP, hypertension, and family history of glaucoma were detected more frequently in the converter group than in the non-converter group. Among TopSS parameters, cup-to-disc ratio, effective area, volume above, maximum slope, and neuroretinal rim area showed statistically significant change. Changes of the neuroretinal rim were prominent in superior and inferior sectors. CONCLUSIONS: Among TopSS parameters, cup-to-disc ratio, effective area, volume above, and neuroretinal rim are useful in detecting the progression of glaucoma. Furthermore, neuroretinal rim changes in each sector may provide clinically relevant information in detecting and monitoring the progression of glaucoma.

Change in Optic Nerve Head Topography in Progression of Early Glaucoma

PURPOSE: To investigate the clinical manifestation and the structural optic disc changes according to the development of reproducible visual field defects in a group of preperimetric patients converting to early glaucoma. METHODS: Standard automated perimetry (Humphrey Field Analyzer) was performed every six months in 294 preperimetric patients. Each subject was classified as either converter or non-converter according to glaucomatous visual field changes, and the clinical manifestations were analyzed retrospectively. Sequential optic disc images were obtained using the TopSS scanning laser ophthalmoscope (TopSS(TM)) and optic disc parameters were measured to determine if any change had occurred. RESULTS: A total of 44 eyes from 44 subjects (14.9%) in 294 patients subsequently developed early glaucomatous field loss (converters). The progression rate of visual field defect is 0.43dB/year. In respect to age, sex, refractive error, and diabetes mellitus, no significant differences were observed. Elevated IOP, hypertension, and family history of glaucoma were detected more frequently in the converter group than in the non-converter group. Among TopSS parameters, cup-to-disc ratio, effective area, volume above, maximum slope, and neuroretinal rim area showed statistically significant change. Changes of the neuroretinal rim were prominent in superior and inferior sectors. CONCLUSIONS: Among TopSS parameters, cup-to-disc ratio, effective area, volume above, and neuroretinal rim are useful in detecting the progression of glaucoma. Furthermore, neuroretinal rim changes in each sector may provide clinically relevant information in detecting and monitoring the progression of glaucoma.

Discriminating Ability of Scanning Laser Polarimetry with Variable Corneal Compensation in Normal and Glaucomatous Eyes

PURPOSE: We investigated the diagnostic ability of scanning laser polarimetry with variable corneal compensation (GDx VCC) parameters to distinguish glaucomatous eyes with different degrees of visual field abnormality from normal eyes. METHODS: Subjects were divided into a control group (n=47) and an early to moderate glaucoma group (n=100). The latter included 53 early glaucoma patients (mean deviation > -6dB with a Humphrey Field Analyzer). Using a receiver operating characteristic (ROC) curve, the diagnostic power of GDx VCC parameters was analyzed and the correlations between those parameters and Humphrey Field Analyzer (HFA) indices were statistically analyzed. RESULTS: Nerve fiber indicator (NFI) provided the best discriminating ability with the highest area under the ROC curve (AUROC) value for detecting eyes with early to moderate perimetric glaucoma. TSNIT average showed the highest AUROC value for detecting eyes with early perimetric glaucoma. The optimal NFI cut-off value to discriminate between the control group and early to moderate group was 22, offering the best combination of sensitivity (88.0%) and specificity (83.0%). The optimal TSNIT average cut-off value to discriminate between the control group and early glaucoma group was 53.49 micrometer, providing the best combination of sensitivity (84.9%) and specificity (85.1%). Most of the thickness parameters showed higher AUROC values than those of the ratio or modulation parameters. A statistically significant correlation was found between the GDx VCC parameters and HFA indices. CONCLUSIONS: Measurement of the retinal nerve fiber layer (RNFL) by scanning laser polarimetry with variable corneal compensation is useful in discriminating between normal and glaucomatous eyes.

Ability of Scanning Laser Polarimetry (GDx) to Discriminate among Early Glaucomatous, Ocular Hypertensive and Normal Eyes in the Korean Population

We investigated the ability of the GDx-Nerve Fiber Analyzer (NFA) to discriminate between normal and early glaucomatous eyes among Korean individuals by reviewing the medical records of 217 consecutive subjects: 61 early glaucoma patients, 68 ocular hypertensive patients, and 88 normal subjects. GDx parameters were compared using ANOVA. The Receiver Operating Characteristics (ROC) curve for each GDx-NFA variable was used to diagnose each parameter, and Pearson correlation coefficients were calculated to assess the association between GDx-NFA parameters and visual field indices in early glaucoma. The best GDx parameters to discriminate between early glaucomatous and normal subjects were the number, maximum modulation, ellipse modulation and inferior ratio (i.e. area under the ROC curve > 0.8). A value for the Number of equal to or greater than 27 was optimal for detecting early glaucoma, with a sensitivity of 80.3% and specificity of 80.7%. In addition, symmetry was positively correlated with the corrected pattern standard deviation (CPSD) among visual field indices in early glaucoma.

Sensitivity and Specificity of Frequency Doubling Perimetry FDPin Early Glaucoma

We evaluated the sensitivity and specificity of Frequency doubling perimetry[FDP]with fourty-nine normal subjects and twenty-six patients of early glaucomatous field change. We regarded Humphrey field analyzer[HFA]30-2 GHT as gold standard. 'True positive 'was regarded as 'outside normal limit 'or P-value of MD or PSD below 0.05 at HFA, 'abnormal 'at FDP P-value of MD or PSD below 0.05. MD of early glaucoma was -5.4 decibel at HFA and -6.61 decibel at FDP, Sensitivity of early glaucoma was 96.1%with FDP and 84.6%with HFA;specificity, 89.7%with FDP and 83.6%with HFA. We could confirm FDP threshold test showed good sensitivity in detecting early glaucoma. Especially, use of PSD increased efficiency of the test.

Clinical Significance of Nasal Step Index in Early Glaucoma

Nasal step index(NSI) is an index of light sensitivity of the nasal step area, the early sign of visual field defects in glaucoma. It represents the asymmetry between the upper-nasal and lower-nasal quadrant within 30 degree field. We applied this index to 66 eyes with normal visual field and 204 eyes with mild-to-moderate glaucomatous visual field defect (mean defect(MD)or=1.04), respectively. AUC values related to the validity of this study were NSI-1:0.38, NSI-2;0.44 and MD;0.83 in early glaucoma patients. But AUC values in high NFBI patients were NSI -1;0.50, NSI -2;0.50, MD;0.82. Therefore, NSI is shown to have lesser diagnostic value than MD in detection of early glaucoma in this study.

The Inspection for the Clinical Usefulness of the Pericecal Index in Early Glaucoma Automated Visual Fields

Many visual field indices have been used for the rapid, precise evaluation of the Humphrey automated visual field. The clinical usefulness of Pericecal Index(PI), the mean sensitivity of 11 test points around the blind spot, was studied in the diagnosis of early glaucoma. PI was calculated in 60 eyes with low tension glaucoma(LTG)[mean defect<10dB], 60 eyes with early visual field change[general reduction of sensitivity(GRS)] and in 60 normal eyes. The difference between glaucomatolls eyes and normal eyes was statistically significant(p<0.01). And also compared PI with the mean sensitivity of 11 control points, located at same eccentricity in lower field and used this as the Control Area(CA). More over, the mean sensitivity of these points in glaucomatous and normal eyes was compared. The difference between PI and CI was only statistically significant in glaucomatolls eyes. On the other hand, We found a significant difference between normal and glaucomatolls control points. Thus we concluded that PI can be the useful visual field indix for the diagnosis of early glaucoma.

Comparisons Between Nerve Fiber Bundle Index and Mean Defect in Early Glaucoma

Nerve fiber bundle index(NFBI) is a new index which detects visual field depression in 21 nerve fiber bundle zones, reflecting the topographical arrangement of visual field defects. We applied this index to 39 eyes with normal visual field and 131 eyes with early glau-comatous field defect(mean defect