Usefulness of Automated Measurements of Localized Retinal Nerve Fiber Layer Defects Area Using Significance Map

PURPOSE: To evaluate the usefulness of automated measurements of the localized retinal nerve fiber layer (RNFL) defects area in patients with glaucoma. METHODS: Fifty one patients with localized RNFL defects in RNFL red-free photographs and 53 healthy subjects were included. All participants were imaged with 3D spectral-domain optical coherence tomography (OCT). The area of defects was measured with the RNFL significance map (red = p < 1% and yellow = p < 5%) using Image J manually and Matlab software automatically. The area under the receiver operating characteristic curve (AUC) was calculated for the RNFL defect area of the RNFL photograph and RNFL maps, circumpapillary RNFL thickness, optic disc parameter, and macular inner retina thickness. RESULTS: High correlation was observed between manually and automatically measured defect areas in the significance map (red area r = 0.904, red and yellow area r = 0.890). The AUC for manually and automatically measured defects area (0.987, 0.966; p < 5%, p = 0.31, respectively) in the significance map was comparable. The latter demonstrated slightly higher but insignificant difference in AUC for inferior quadrant circumpapillary RNFL thickness (0.936; p = 0.22) and was significantly higher than the inferior ganglion cell layer plus inner plexiform layer thickness (0.894) and vertical cup to disc ratio (0.869) (p = 0.018, p = 0.008, respectively). CONCLUSIONS: The automated measurements of the RNFL defect area in the significance map performed adequately in detecting localized RNFL defects and had a better performance than macular inner retina and optic nerve parameters.

Comparison of Retinal Nerve Fiber Layer Thickness Measured by Spectral-Domain and Time-Domain Optical Coherence Tomography

PURPOSE: To compare retinal nerve fiber layer (RNFL) thickness measured by time domain (Stratus) and spectral domain (3D) optical coherence tomography (OCT). METHODS: Sixty-nine normal subjects and 92 glaucoma patients were included in the present study. Peripapillary RNFL thickness was measured with Stratus fast RNFL scan and 3D optic disc cube scan on the same day. The relationship between RNFL thickness measurements of the two OCTs were evaluated using a Pearson's correlation analysis. A Bland-Altman plot was used for the comparison of Stratus-OCT and 3D-OCT. RESULTS: In all subjects, average, superior, and inferior quadrant RNFL thicknesses measured by Stratus-OCT were thicker than those measured by 3D-OCT. In contrast, temporal and nasal quadrant RNFL thicknesses measured by 3D-OCT were thicker than those measured by Stratus-OCT. Although there were absolute value differences in RNFL thicknesses, high correlation was observed between Stratus-OCT and 3D-OCT (average: r = 0.897, temporal quadrant: r = 0.728, superior quadrant: r = 0.811, nasal quadrant: r = 0.678, and inferior quadrant: r = 0.905). Bland-Altman plots showed that Stratus-OCT values were greater than 3D-OCT values with relatively high RNFL thickness and the opposite with low RNFL thickness. CONCLUSIONS: For thicker RNFL, Stratus-OCT measurements tend to be greater than 3D-OCT, while for thinner RNFL, 3D-OCT measurements tend to be greater than Stratus-OCT. This difference must be taken into account if comparing measurements made with a Stratus-OCT to the measurements of a 3D-OCT.

Comparison of Diagnostic Ability of 3D and Stratus Optical Coherence Tomography in Early Glaucoma

PURPOSE: To compare the ability of three dimensional spectral-domain optical coherence tomography (3D OCT) and Stratus OCT to detect early glaucoma. METHODS: The optic disc topographic and retinal nerve fiber layer (RNFL) thickness parameters were measured by 3D OCT and Stratus OCT in 69 normal eyes and 48 early glaucoma eyes. The discriminating abilities of the two techniques for detection of glaucoma were compared by the area under the receiver operating characteristic curves (AUC). RESULTS: The best Stratus OCT parameters and criterion that differentiated normal from early glaucoma based on AUC were horizontal integrated rim width (0.85) for optic nerve head parameters, inferior quadrant (0.88) for RNFL parameters, and > or =1 clock-hour abnormal at the 5% level (0.81) based on the normative database for criteria. The best 3D OCT parameters and criterion that differentiated normal from early glaucoma were vertical cup-to-disc ratio (0.85), 11 o'clock RNFL thickness (0.86), and > or =1 clock-hour abnormal at the 1% level (0.78), respectively. When all corresponding the best parameters and criterion were compared, there were no significant differences between the AUCs for Stratus OCT and 3D OCT (p = 0.95, p = 0.73, p = 0.45, respectively). CONCLUSIONS: Stratus OCT and 3D OCT had similar diagnostic ability for detection of early glaucoma.

Optic Disc Pit with Peripapillary Retinoschisis Presenting as a Localized Retinal Nerve Fiber Layer Defect

A 59-year-old woman was referred to our clinic for a glaucoma evaluation. The visual acuity and intraocular pressure were normal in both eyes. However, red-free fundus photography in the left eye showed a superotemporal wedge-shaped retinal nerve fiber layer defect, and visual field testing showed a corresponding partial arcuate scotoma. In an optical coherence tomography examination, the macula was flat, but an arcuate-shaped peripapillary retinoschisis was found. Further, the retinoschisis seemed to be connected with a superotemporal optic pit shown in a disc photograph. After 3 months of a topical prostaglandin analogue medication, the intraocular pressure in the retinoschisis eye was lowered from 14 to 10 mmHg and the peripapillary retinoschisis was almost resolved. We report a rare case of an optic disc pit with peripapillary retinoschisis presenting as a localized retinal nerve fiber layer defect.

A Case of Optic Nerve Atrophy with Severe Disc Cupping after Methanol Poisoning

We report a rare case of optic nerve atrophy with severe disc cupping resulting from methanol poisoning. A 30-year-old man presented to the hospital complaining of decreased visual acuity in both eyes a day after drinking alcohol containing methanol. His initial visual acuity allowed for only visualizing hand motion and not corrected in either eye. Initial intraocular pressure was within normal limits in both eyes. Initial fundus examination showed optic disc swelling in both eyes. Four years later, he visited our hospital for an eye evaluation. Visual acuity in both eyes still only allowed for visualizing hand motion. No nystagmus was observed in either eye during the optokinetic nystagmus test, and no waves were found in a visual evoked potential test. No specific change was noted on brain magnetic resonance imaging. On fundus examination, there was disc pallor in both eyes and disc cupping with a high cup/disc (C/D) ratio above 0.9 in the left eye. C/D ratio of the right eye was 0.5. Methanol poisoning may induce glaucomatous disc cupping in the late stage as well as optic atrophy. One possible mechanism of disc cupping is ganglion cell loss due to acute demyelination of the retrobulbar optic nerve. This report is the first photographic evidence of methanol induced optic disc cupping in Korea.

False Negative Findings of Optical Coherence Tomography in Eyes with Localized Nerve Fiber Layer Defects

PURPOSE: To identify the risk factors associated with false negative findings of optical coherence tomography (Stratus OCT) in patients with photographic localized retinal nerve fiber layer (RNFL) defects. METHODS: Twenty-four patients with preperimetric glaucoma and 173 patients with perimetric glaucoma, all with localized RNFL defects were included in the present study. The patients were divided into 2 groups according to the presence or absence of detection of photographic defects by OCT. Gender, age, refractive error, diabetes, hypertension, central corneal thickness, type of glaucoma, mean deviation, pattern standard deviation, average RNFL thickness, disc area, and photographic RNFL defect related variables (location, number, and angular width) were compared between the 2 groups. Each variable was initially evaluated by univariate analysis and significant variables (p < 0.1) were included in the logistic regression analysis. RESULTS: Photographic RNFL defects were not detected by OCT in 51 (25.9%) of the 197 eyes. The angular locations and widths of RNFL defects by OCT were significantly correlated with those of RNFL defects by red-free RNFL photographs (Pearson correlation coefficient R = 0.98 and 0.64, respectively). Logistic regression analysis revealed the risk factors for false negative findings of OCT included average RNFL thickness (odds ratio = 1.106, 95% confidence interval [CI] = 1.057-1.156, p < 0.001) and angular width of defect (odds ratio = 0.929, 95% CI = 0.884-0.977, p = 0.004). CONCLUSIONS: This present study suggests that false negative findings of OCT in patients with photographic localized RNFL defects were associated with thicker RNFL thickness and smaller angular width of RNFL defect.

Visual Field Cluster Map Corresponding to Retinal Nerve Fiber Layer Sectors in Glaucoma

PURPOSE: To generate a map relating visual field (VF) test points to corresponding areas of the retinal nerve fiber layer (RNFL) measured with optical coherence tomography (OCT) in patients with localized RNFL defects. METHODS: Twenty-four patients with preperimetric glaucoma and 173 patients with perimetric glaucoma, all with localized RNFL defects, underwent standard automated perimetry (SAP) and OCT measurements. To define zones of related point, factor analysis of the mean thresholds for the SAP test points was performed, independently for each hemifield. A map relating the VF zones to the 12 OCT sectors was plotted based on the strongest correlations between both techniques. RESULTS: Factor analysis divided the VF points into five VF zones for each hemifield. Distribution of the VF zones for the superior and inferior hemifields was slightly asymmetric. Linear regression results showed that superior VF zones corresponding to the superior arcuate and nasal step regions were best correlated with 6- and 7-o'clock RNFL sectors (inferior and inferior temporal) of thickness (r = 0.51-0.59). RNFL thinning (defined by abnormal sector at p < 5%) and regional decreases in SAP sensitivity (defined by abnormal pattern deviation at p < 5%) were topographically related. CONCLUSIONS: A newly developed VF cluster map revealed significant topographical structure-function relationships, especially in the arcuate and nasal step region of the VF.

Diagnostic Ability of Stratus OCT Using Korean Normative Database for Early Detection of Normal-Tension Glaucoma

PURPOSE: To determine if korean normative database improve diagnostic ability of Stratus OCT for detection of glaucoma. METHODS: Peripapillary retinal nerve fiber layer (RNFL) and optic nerve head regions were measured using a Stratus OCT. The normative data were collected from 129 normal individuals. We obtained values at the 5% and 1% levels according to the disc area stratified into equal thirds to minimize the error by the individual variation of optic disc size and these levels were considered abnormal. One eye of each 94 normal-tension glaucoma patients with early visual field defects (mean deviaton = -3.84+/-1.40dB) and 87 another normal subjects were enrolled. Glaucoma was defined by visual field defects. RESULTS: The use of Korean normative database had higher sensitivity and no significant difference of specificity than that of a Stratus OCT except for a few parameters. The criteria that show the highest diagnostic ability were 1 > or = quadrants RNFL thickness abnormal at the or = clock hours abnormal at the < 5% when using a Stratus OCT normative database (sensitivity = 71.3%, specificity = 87.4%) (p=0.004, p=0.180, respectively, McNemar test). CONCLUSIONS: The criterion using a Korean normative database had higher sensitivity and no difference of specificity compared with criterion using a Stratus OCT normative database. The best criterion using a Korean normative database may be helpful for early detection of normal-tension glaucoma.

Discrimination between Normal and Early Stage of Glaucomatous Eyes Using the Stratus Optical Coherence Tomography

PURPOSE: To evaluate the diagnostic ability of Stratus optical coherence tomography (OCT) parameters to distinguish normal eyes from those with early glaucomatous visual field defects. METHODS: One eye each of 52 normal-tension glaucoma patients with early visual field defects (mean deviation, -3.98+/-1.30dB; range, -0.01 to -5.86dB) and 88 age-matched normal subjects were enrolled. The Peripapillary retinal nerve fiber layer (RNFL) and optic nerve head regions were scanned using the Stratus OCT. Areas under the receiver operating characteristic curve (AROC) and the sensitivity and specificity for various OCT parameters were used to assess the performance of OCT. RESULTS: The AROC for the C/D area ratio was 0.865. Other high AROC values included the vertical C/D ratio (0.848), the average RNFL thickness (0.813), and the RNFL thickness in the inferior quadrant (0.791). A stepwise discriminant analysis found that a combination of the C/D area ratio and RNFL thickness in the inferior quadrant could correctly identify 86.4% of the normals and 80.8% of the glaucoma patients (AROC=0.893). CONCLUSIONS: In our sample of patients with early visual field defects, Stratus OCT parameters showed moderate discriminating abilities. Combining the C/D area ratio and RNFL thickness in the inferior quadrant by discriminant analysis improved the diagnostic ability to detect glaucoma.

Factors Influencing Optic Disc and Retinal Nerve Fiber Layer Parameters Measured by Optical Coherence Tomography

PURPOSE: To determine the factors influence retinal nerve fiber layer (RNFL) and optic nerve head (ONH) parameters measured by Stratus optical coherence tomography (OCT). METHODS: Topographic RNFL thickness and optic disc parameters of 129 healthy Korean subjects of aged 14 to 87 were measured using the fast retinal nerve fiber layer thickness and fast optic disk algorithms of Stratus OCT. One eye of each subject was randomly selected for statistical analysis. Using multiple linear regression, the effect of optic disc area, age, refractive error, and zone beta on each parameter was analyzed. RESULTS: Large discs had large horizontal integrated rim width (HIRW), cup area, rim area, C/D area ratio, and vertical C/D ratio. The thickness of average, superior, inferior, and nasal quadrant RNFL increased significantly with an increase in optic disc area. Average and superior quadrant RNFL thickness, and HIRW decreased with age. Refractive error showed a correlation with the vertical integrated rim area, horizontal C/D ratio, and temporal quadrant RNFL thickness. Gender and zone beta had no statistically significant influence on ONH and RNFL parameters. CONCLUSIONS: This study shows that optic disc size affects most RNFL thickness and ONH parameters. Because of the relationships revealed in this study, optic disc area in addition to age should be considered when the Stratus OCT RNFL thickness and ONH parameters are interpreted.

The Influence of Demographic Characteristics on the Qualitative Signs of Glaucomatous Optic Disc

PURPOSE: To evaluate the influence of age, gender, and refractive error on the qualitative signs of glaucomatous optic nerve damage in normal eyes. METHODS: We evaluated color optic disc photographs for the presence or absence of 10 qualitative signs: rim shape alteration (alteration of ISN'T rule), thinnest rim width outside the temporal sector, rim notch, optic disc hemorrhage, baring of circumlinear vessel, bayonetting of vessel, nasalization of vessel, abnormally large peripapillary atrophy, abnormal form of peripapillary atrophy, and zone beta in 181 eyes of 181 normal subjects. The influence of age, gender, and refractive error on each qualitative sign was analysed by multiple logistic regression. RESULTS: Refractive error was related to zone beta (odds ratio=2.29, 95% confidence interval [CI]=1.21~4.33, p=0.009) and the frequency of zone beta was higher in myopic eyes. Age was weakly associated with abnormally large peripapillary atrophy (odds ratio=1.03, 95% CI=1.01~1.06, p=0.02). Gender, on the other hand, had no influence on qualitative signs. CONCLUSIONS: Our findings indicate that the qualitative signs of glaucomatous optic nerve damage were not affected by age, gender, and refractive error, except for zone beta and abnormally large peripapillary atrophy. Myopia was related to zone beta, and age was related to abnormally large peripapillary atrophy in normal eyes.

Optic Nerve Head Appearance in Chronic Primary Angle-Closure Glaucoma and Primary Open-Angle Glaucoma

PURPOSE: To evaluate the morphologic characteristics of the optic nerve head in chronic primary angle-closure glaucoma (CPACG) and primary open-angle glaucoma (POAG). METHODS: The study included 77 normal subjects, 82 patients with CPACG, and 120 patients with POAG. Age and refraction in the POAG and normal control groups were matched to those of the CPACG group. Using color optic disc photographs, the presence or absence of qualitative signs for differentiating between normal and glaucoma eyes were recorded. RESULTS: A rim notch was observed in 9 eyes (11.0%) in the CPACG group and in 27 eyes (22.5%) in the POAG group (P=0.04). Disc hemorrhage was found in 4 eyes (3.3%) in the POAG group and was not found in the CPACG group (P=0.15). Neither groups varied significantly in frequency of rim shape alteration (alteration of ISN'T rule), thinnest rim width outside the temporal sector, baring of the circumlinear vessel, bayonetting of vessel, nasalization of vessel, abnormally large peripapillary atrophy, abnormal form of peripapillary atrophy, or zone beta. CONCLUSIONS: Compared with the CPACG group, rim notches and disc hemorrhages were found more often in the POAG group. These results suggest that CPACG and POAG have at least partially different pathogenesis.

Comparison of Glaucomatous Optic Nerve Damage in Primary Angle-Closure Glaucoma with and without Acute Attack

PURPOSE: To compare the glaucomatous optic nerve damage in primary angle-closure glaucoma (PACG) with acute attack (acute PACG; AACG) and PACG without acute attack (chronic PACG; CACG). METHODS: The study subjects were 84 normal individuals, 130 AACG patients, and 86 CACG patients. Color optic disc photographs were evaluated for the presence or absence of 10 qualitative signs to differentiate between normal and glaucomatous optic discs. RESULTS: Abnormally shaped rim width (alteration of ISN'T rule), bared circumlinear vessel, vessel bayonetting, rim width narrower than the temporal sector, and zone beta (nasal and superotemporal sectors) were detected more frequently in the CACG group than in the AACG group (P< 0.05). The most accurate qualitative sign was abnormally shaped rim width in both groups. The specificity and sensitivity of abnormally shaped rim width were 71.4% and 60.8% for AACG, and 71.4% and 81.4% for CACG, respectively. CONCLUSIONS: The optic disc damage is greater in CACG than in AACG.

Glaucomatous Optic Nerve Damage in the Fellow Eyes of Acute Angle-Closure Glaucoma

PURPOSE: To determine whether glaucomatous optic nerve damage occurs in the fellow eyes of patients with unilateral acute primary angle-closure glaucoma. METHODS: This study included both eyes of 75 subjects with unilateral acute primary angle-closure glaucoma in one eye, and 92 eyes of age- and refraction-matched normal controls. The presence or absence of qualitative signs for differentiating between normal and glaucoma eyes, vertical cup to disc ratio, and extent of zone beta were recorded. All subjects underwent examination with a Humphrey Field Analyser. RESULTS: Twelve fellow eyes (16%), 28 attacked eyes (37.3%), and no eyes in the control group had a vertical cup to disc ratio of 0.7 or greater (p<0.05). Thinnest rim width outside the temporal sector, rim shape alteration (alteration of ISN'T rule), baring of circumlinear vessel, and abnormal form of peripapillary atrophy were detected more frequently in fellow eyes than in normal controls (P<0.05). After excluding the attacked eyes with vertical cup to disc ratios of 0.69 or less and their fellow eyes, interocular correlation of mean deviation (r=0.31), corrected pattern standard deviation (r=0.32), extent of zone beta (r=0.57), and vertical cup to disc ratio (r=0.38) for attacked and fellow eyes were significant (p<0.05). CONCLUSIONS: Some of the fellow eyes of patients with unilateral acute primary angle-closure glaucoma had glaucomatous optic nerve damage, particularly the fellow eyes with a large cup to disc ratio.

Diagnostic Ability of Qualitative Signs and Characteristics of Optic Disc in Angle-Closure Glaucoma and Open-Angle Glaucoma

PURPOSE: To evaluate the ability of qualitative signs for glaucoma diagnosis, both alone and in combination, to discriminate between eyes with and without glaucomatous visual field damage. Furthermore, we investigated whether the characteristic optic disc changes in primary angle-closure glaucoma (PACG) differ from those in primary open-angle glaucoma (POAG). METHODS: Using color polaroid optic disc photographs, we examined 10 qualitative signs in 177 patients with PACG, 184 patients with POAG, and 181 normal subjects. RESULTS: Rim notches and rim shape alteration were found more frequently in patients with POAG than in those with PACG (p-6 dB) of the PACG and POAG groups, the best qualitative sign was rim shape alteration, and area under the receiver operating characteristic (ROC) curve was 0.696 and 0.768, respectively. The area under the ROC curve for the combination of qualitative signs was 0.802 and 0.918, respectively. CONCLUSIONS: These results suggest that glaucomatous disc damage was less pronounced in the PACG eyes than in the POAG eyes with similar visual field damage. A combination of the qualitative signs of optic disc using multiple logistic regression modelling improved the diagnostic ability.

Accuracy of Optic Disc Parameters Obtained by the Heidelberg Retina Tomograph in the Diagnosis of Glaucoma

PURPOSE: To determine which optic disc topographic parameters, obtained by the Heidelberg Retina Tomograph (HRT), are most useful to distinguish normal eyes from those with early to moderate glaucomatous visual field defects. METHODS: From each of 92 normal subjects and 154 patients with primary open-angle glaucoma one randomly selected eye was studied. The Humphrey perimeter, program C 30-2 visual fields, and 13 HRT parameters (software 2.01, includes rim to disc area ratio) were utilized. Because some of the optic disc parameters depend on the optic disc area, these parameters were corrected for the effect of disc area. The total glaucoma group was divided into three subgroups according to the visual field defects: early (mean deviation [MD] >-6 dB, 65 eyes), moderate (MD -6 to -12 dB, 49 eyes), and severe (MD <-12 dB, 40 eyes) glaucoma groups. RESULTS: In eyes with early glaucoma (MD = -3.43 +/- 1.60 dB), the sensitivity, specificity, accuracy, and areas under the receiver operating characteristic curve were, respectively: rim area (69%, 71%, 70%, 0.802), rim to disc area ratio (69%, 72%, 71%, 0.799), cup area (72%, 70%, 71%, 0.789) and cup to disc area ratio (69%, 70%, 69%, 0.790). In eyes with moderate glaucoma (MD = -8.75 +/- 1.88 dB), they were, respectively: rim area (78%, 86%, 83%, 0.872), rim to disc area ratio (76%, 86%, 82%, 0.869), cup area (76%, 87%, 83%, 0.864) and cup to disc area ratio (78%, 84%, 82%, 0.862). There was considerable overlap in HRT parameters between the normal and early glaucoma groups. CONCLUSIONS: The diagnostic value of single optic disc parameter had its limitations in the diagnosis of early stage glaucoma.

The Effect of Intravitreal Triamcinolone Acetonide on Intraocular Pressure

PURPOSE: To evaluate the effect of a single intravitreal injection of 4.0 mg/0.1ml triamcinolone acetonide on intraocular pressure (IOP). METHODS: Retrospective studies were conducted by reviewing the charts of 26 eyes of 24 patients that were followed up for 16 weeks after intravitreal triamcinolone injection. The IOPs before and after triamcinolone injection were measured with Goldmann applanation tonometer. RESULTS: Within 16 weeks after intravitreal triamcinolone acetonide injection, 23 of 26 eyes (88.5%) demonstrated an increment in IOP of 5 mmHg or greater, and 6 of 26 (23.1%) had an increment of 10 mmHg or greater. The mean duration of the increase in IOP of 5 mmHg or greater was 5.5 weeks (standard deviation=4.4), and the mean time to reach maximum IOP was 6.6 weeks (standard deviation=4.4). The difference between the mean pre-injection IOP (14.12 mmHg, n=26) and the maximum post-injection IOP (24.65 mmHg, n=26) was statistically significant (P<0.001). All eyes that needed treatment responded to topical glaucoma medication. CONCLUSIONS: An increment in IOP is a common complication after a single intravitreal injection of 4.0 mg/0.1ml triamcinolone acetonide and despite this serious increment in IOP, it was controlled by topical glaucoma medication.

Characteristics and Risk Factors for Visual Field Defects in Acute Primary Angle-Closure Glaucoma

PURPOSE: To determine the characteristics of visual field defects in acute primary angle-closure glaucoma and identify risk factors affecting such field defects. METHODS: Automated static perimetry was performed in 60 patients at least 3 months after remission of the acute attack. Glaucomatous visual field defects were defined as 3 or more contiguous points on the pattern deviation plot depressed at p<5% level and one point depressed at a p<1% level. RESULTS: Visual field defects were seen in 40 (67%) of 60 patients. The upper nasal area was most frequently and more severely affected. Only 2 cases (5%) presented a localized type defect. The multiple logistic regression showed that sex (odds ratio=23.1, 95% confidence interval [CI]=3.2 ~ 168.6, p=0.002) and vertical cup to disc ratio (odds ratio=5.5, 95% CI=1.2 ~ 24.8, p=0.03) were significant risk factors for visual field defects. Duration of the acute attack was a marginally significant risk factor (odds ratio=5.2, 95% CI=0.8 ~ 31.8, p=0.08). CONCLUSIONS: The upper nasal visual field was affected most frequently and more severely. The localized defect was rare. Women and the large vertical cup to disc ratio were associated with increased risk for visual field defects. A longer duration of the acute attack seems to more likely develop visual field damage.

Linear Discriminant Function for Detecting Glaucomatous Optic Nerve Damage

PURPOSE: To determine whether the linear discriminant function of optic disc parameters measured with confocal scanning laser tomography can improve the differentiation between normal and glaucoma eyes. METHODS: One eye was randomly selected from 92 normal subjects and 154 primary open-angle glaucoma patients. The Humphrey perimeter, program C 30-2 visual fields, and 13 Heidelberg Retina Tomograph parameters (software 2.01, includes rim to disc area ratio) were utilized. Glaucoma was defined as an abnormal visual field and intraocular pressure greater than 22 mm Hg. The appearance of the optic nerve head was not taken as a diagnostic criterion. Because some of the optic disc parameters depend on the size of the optic disc, these parameters were corrected for the effect of disc area. RESULTS: Stepwise discriminant analysis indicated that the most valuable optic disc parameters for the detection of glaucomatous optic nerve damage were rim area for the early glaucoma group (65 eyes, average mean deviation [MD] = -3.43 +/- 1.60 dB) and mean retinal nerve fiber layer thickness, rim volume, and rim area for the moderate glaucoma group (49 eyes, average MD = -8.75 +/- 1.88 dB). The sensitivity, specificity, and accuracy were 69%, 71%, and 70%, respectively, for the early glaucoma group and 78%, 92%, and 87%, respectively, for the moderate glaucoma group. CONCLUSIONS: The linear discriminant function was not sensitive enough to detect early glaucomatous optic nerve damage. Hence the result of discriminant analysis has to be interpreted in the context of all other clinical data available.

The Influence of Age, Gender, Refractive Error, and Optic Disc Area on the HRT Parameters in Normal Eyes

PURPOSE: To study the influence of age, gender, refractive error, and optic disc size on the optic disc parameters measured with the Heidelberg Retina Tomograph (HRT; software 2.01) in normal eyes. METHODS: Ninety-two normal subjects (mean refractive error +/- SD: -0.15 +/- 1.64 D, range -6.63 to +3.38 D) were examined using HRT. The influence of age, refraction, and disc area on each parameter was analysed by multiple linear regression. RESULTS: Large discs had large values of cup area, cup volume, rim area, cup to disc area ratio, and mean cup depth. Large discs had small values of rim to disc area ratio. However, rim volume, maximum cup depth, cup shape measure, height variation contour, mean retinal nerve fiber layer thickness, and retinal nerve fiber layer cross-sectional area were not related to disc area. Most parameters were independent of age or refractive error except for a few parameters. Age was weakly related to disc area. Refractive error was weakly associated with cup shape measure. Gender had no statistically significant influence on optic disc parameters. CONCLUSIONS: These results indicate that several optic disc parameters have better correlations with the optic disc area than age, gender, and refractive error. These differences must be considered in the evaluation of optic disc for glaucoma.