Retinal Nerve Fiber Layer Measurement Variability with Spectral Domain Optical Coherence Tomography

PURPOSE: To evaluate the effect of the scanning laser ophthalmoscope (SLO) guided re-test mode on short- and long-term measurement variability of peripapillary retinal nerve fiber layer (RNFL) thickness obtained by spectral domain-SLO optical coherence tomography (SD-SLO/OCT). METHODS: Seventy five healthy eyes were scanned 3 times per day (intra-session variability) by both the SLO guided re-test mode and the independent mode of SD-SLO/OCT. Subjects were scanned 3 times by both modes at visits within a 2-week interval (inter-session variability). For testing longitudinal variability, 3 separate exams were performed over 6 months by both modes. The coefficient of variation (CV), reproducibility coefficient (RC) and intraclass correlation coefficient of RNFL thickness were compared between the two modes. RESULTS: The intra-session RC and CV ranged from 5.4 to 12.9 microns and 1.76% to 5.72% when measured by independent mode and 5.4 to 12.5 microns and 1.75% to 5.58% by re-test mode, respectively. The inter-session RC and CV ranged from 5.8 to 13.3 microns and 1.89% to 5.78% by independent mode and 5.8 to 12.7 microns and 1.90% to 5.54% by re-test mode, respectively. Intra-session and inter-session variability measurements were not significantly different between the two modes. The longitudinal RC and CV ranged from 8.5 to 19.2 microns and 2.79% to 7.08% by independent mode and 7.5 to 14.4 microns and 2.33% to 6.22% by re-test mode, respectively. Longitudinal measurement variability was significantly lower when measured by the re-test mode compared to the independent mode (average, p = 0.011). CONCLUSIONS: The SLO guided re-test mode for RNFL thickness measurement in SD-SLO/OCT employing a tracking system improved long-term reproducibility by reducing variability induced by inconsistent scan circle placement.

Glaucoma Progression Detection by Retinal Nerve Fiber Layer Measurement Using Scanning Laser Polarimetry: Event and Trend Analysis

PURPOSE: To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. METHODS: Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). RESULTS: Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (+/-standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 +/- 0.148 microm/yr vs. -0.218 +/- 0.151 microm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. CONCLUSIONS: RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

Characterization of Peripapillary Atrophy Using Spectral Domain Optical Coherence Tomography

PURPOSE: To characterize the features of peripapillary atrophy (PPA), as imaged by spectral-domain optical coherence tomography (SD-OCT). METHODS: SD-OCT imaging of the optic disc was performed on healthy eyes, eyes suspected of having glaucoma, and eyes diagnosed with glaucoma. From the peripheral beta-zone, the retinal nerve fiber layer (RNFL), the junction of the inner and outer segments (IS/OS) of the photoreceptor layer, and the Bruch's membrane/retinal pigment epithelium complex layer (BRL) were visualized. RESULTS: Nineteen consecutive eyes of 10 subjects were imaged. The RNFL was observed in the PPA beta-zone of all eyes, and no eye showed an IS/OS complex in the beta-zone. The BRL was absent in the beta-zone of two eyes. The BRL was incomplete or showed posterior bowing in the beta-zone of five eyes. CONCLUSIONS: The common findings in the PPA beta-zone were that the RNFL was present, but the photoreceptor layer was absent. Presence of the BRL was variable in the beta-zone areas.

Clinical Validation of Visual Field Index

PURPOSE: To determine the associations of visual field index (VFI) with advanced glaucoma intervention study (AGIS) score, mean deviation (MD), pattern standard deviation (PSD), and average retinal nerve fiber layer (RNFL) thickness as measured by optical coherence tomography (OCT) and to evaluate the diagnostic abilities of these parameters. METHODS: One hundred fifteen glaucomatous eyes and 78 healthy eyes were enrolled in this cross-sectional study. Each participant had a Humphrey visual field analyzer test and OCT done. The diagnostic abilities of these parameters were analyzed using the receiver operating characteristic (ROC) curve, and we sought to determine the association of these parameters with VFI by Pearson correlation analysis. RESULTS: The associations between analyzed parameters and VFI were statistically significant (all, p<0.001). The area under the ROC curve (AUROC) value of VFI was greater than that of the MD and AGIS score (all, p<0.001) but was not different from the PSD and RNFL average thickness measured by OCT (p=0.756, p=0.638). CONCLUSIONS: The VFI showed significant associations with AGIS score, MD, PSD, and average RNFL thickness as measured by OCT and revealed similar diagnostic abilities as these parameters.

Structural and Functional Relationships in Glaucoma Using Standard Automated Perimetry and the Humphrey Matrix

PURPOSE: To evaluate and compare correlations between structural and functional loss in glaucoma as assessed by optical coherence tomography (OCT), scanning laser polarimetry (GDx VCC, as this was the model used in this study), standard automated perimetry (SAP), and the Humphrey Matrix (Matrix). METHODS: Ninety glaucomatous eyes identified with SAP and 112 eyes diagnosed using Matrix were independently classified into six subgroups, either S1/M1 (MD>-6dB), S2/M2 (-12

C-reactive Protein and Lipid Profiles in Korean Patients With Normal Tension Glaucoma

PURPOSE: To compare high-sensitivity C-reactive protein (hsCRP) levels and lipid profiles between Korean normal tension glaucoma (NTG) patients and healthy controls. METHODS: This cross-sectional study included 38 Korean patients with NTG and 38 age- and sex-matched healthy control subjects. We excluded the patients with cardiovascular risk factors and other systemic diseases that might affect CRP levels and lipid profiles. Each patient underwent a Humphrey visual field examination and blood sampling for hsCRP and lipid profile analyses. Subsequently, the NTG patients were classified into two groups based on their untreated intraocular pressure (IOP) level: low NTG (LNTG) with IOP13 and 0.05) after exclusion of Korean patients with cardiovascular risk factors. There was no significant association between hsCRP and visual field indices (p>0.05). CONCLUSIONS: High-sensitivity C-reactive protein-related vascular inflammatory conditions may not be directly associated with the development of NTG, regardless of the untreated IOP level.

Performance of Humphrey Matrix Frequency Doubling Technology Perimetry and Standard Automated Perimetry Global Indices

PURPOSE: To evaluate and compare the diagnostic performance of Humphrey Matrix frequency doubling technology perimetry (Matrix) global indices with standard automated perimetry (SAP) for glaucoma discrimination. METHODS: Forty-seven healthy and 63 glaucomatous subjects were included in this study. Glaucoma was defined as having glaucomatous optic disc and glaucomatous visual field defect. Correlations of mean deviation (MD) and pattern standard deviation (PSD) between Matrix and SAP were evaluated. Areas under receiver operating characteristic curves (AUCs) for discriminating healthy from glaucoma, sensitivity, and cut-off value at fixed specificity of MD and PSD were determined in Matrix and SAP. RESULTS: MD and PSD from Matrix were highly correlated with SAP data in glaucomatous eyes (r=0.80, 0.69 p<0.001, <0.001). The AUCs of MD and PSD from Matrix (0.941, 0.921) were of comparable diagnostic capability to SAP data (0.876, 0.923, p=0.068, 0.927). The sensitivity at 90% specificity of MD was 67.9% in SAP, 76.4% in Matrix, with the cut off value of MD at 90% specificity at -3.10dB in SAP and -3.72dB in Matrix. CONCLUSIONS: MD and PSD data from Matrix and SAP significantly correlated in glaucomatous eyes and showed similar diagnostic performance for discriminating healthy from glaucoma however, both MD and PSD are scaled differently on SAP and Matrix, which suggests that application of these parameters in a manner similar to that used in SAP should be employed with caution.

Comparison Between Dynamic Contour Tonometry and Goldmann Applanation Tonometry

PURPOSE: To compare the intraocular pressures (IOPs) measured by dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT), and to investigate the association of IOPs on eyes of varying central corneal thickness (CCT). METHODS: In this prospective study, 451 eyes of 233 subjects were enrolled. IOPs were measured by GAT and DCT. CCT was measured three times and the average was calculated. Each eye was classified into one of three groups according to CCT: low CCT (group A, CCT550 micrometer, n=142). In each group, we investigated the association of CCT with IOP measurement by GAT and DCT. RESULTS: The IOPs measured by GAT and DCT were significantly associated for all eyes (R=0.853, p<0.001, Pearson correlation). CCT was related with both IOP measurement by GAT and DCT with statistical significance (mixed effect model, p<0.001). However, subgroup analysis showed that CCT affected IOP measured by GAT for groups B and C, whereas it affected IOP measured by DCT only for group C. CONCLUSIONS: IOP measured by DCT was not affected by CCT in eyes with low to normal CCT, whereas this measurement was affected in eyes of high CCT range. CCT may have less effect on IOP measurements using DCT than those obtained by GAT, within a specified range of CCT.

Twenty-Four Hour Blood Pressure Pattern in Patients With Normal Tension Glaucoma in the Habitual Position

PURPOSE: To investigate the relationship between blood pressure (BP) parameters in the habitual position and glaucomatous damage at initial presentation in patients with untreated normal tension glaucoma (NTG). METHODS: Fifty-four eyes from 54 subjects diagnosed with NTG were consecutively enrolled. BP was measured with an automated ambulatory monitoring device in the habitual position during 24-hour in-hospitalization. Patients were classified into three groups: non-dippers, dippers, and over-dippers. corresponded to the degree of reduction in their nocturnal mean arterial pressure (MAP) compared with their diurnal MAP. Regression models were used to evaluate potential risk factors, including: age, pre-admission office intraocular pressure (IOP), central corneal thickness (CCT), and BP parameters. Functional outcome variables for glaucomatous damage included mean deviation (MD) and pattern standard deviation (PSD) on a Humphrey field analyzer (HFA). Anatomic outcome variables were TSNIT score (temporal, superior, nasal, inferior, and temporal) average, superior average, inferior average, and nerve fiber indicator (NFI) score on scanning laser polarimetry with variable corneal compensation (SLP-VCC; GDx-VCC). RESULTS: Marked systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP fluctuation were noted in the over-dipper group (p<0.05). A linear regression analysis model revealed that nocturnal trough DBP and MAP, average nocturnal SBP, and MAP were all significantly associated with a decreased average TSNIT score and an increased NFI score. CONCLUSIONS: Nocturnal BP reduction estimated in the habitual position was associated with structural damage in eyes with NTG. This finding may suggest systemic vascular etiology of NTG development associated with nocturnal BP reduction.

Evaluation of Glaucomatous Damage in the Fellow Eyes of Patients With Unilateral Retinal Vein Occlusion

PURPOSE: To investigate the visual field (VF) and retinal nerve fiber layer (RNFL) status of the fellow eyes in patients with unilateral retinal vein occlusion (RVO). METHODS: Fifty patients with unilateral RVO and 35 normal control subjects wereconsecutively recruited. Humphrey VF parameters and RNFL status using scanning laser polarimetry with variable corneal compensation (GDx-VCC) were compared between the fellow eyes of the patients with unilateral RVO and control eyes. We also assessed the risk factors for the development of glaucomatous damage in the fellow eyes of unilateral RVO patients. RESULTS: Twelve fellow eyes out of 50 patients with unilateral RVO showed glaucomatous VF and RNFL changes assessed by GDx-VCC. VF indices and RNFL thickness parameters in the study group were significantly lower than those in the control group (p<0.05). Increased age and vertical cup-to-disc ratio were significantly associated with severity of VF and RNFL damage in the fellow eye of unilateral RVO patients (p<0.05). CONCLUSIONS: The fellow eyes in patients with unilateral RVO showed significantly worse VF indices and lower RNFL thickness than normal control eyes. The glaucomatous change should be carefully monitored in the fellow eyes of unilateral RVO patients.

Relationship between Scanning Laser Polarimetry with Enhanced Corneal Compensation and with Variable Corneal Compensation

PURPOSE: To evaluate the structure-function relationships between retinal sensitivity measured by Humphrey visual field analyzer (HVFA) and the retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry (SLP) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC) in glaucomatous and healthy eyes. METHODS: Fifty-three eyes with an atypical birefringence pattern (ABP) based on SLP-VCC (28 glaucomatous eyes and 25 normal healthy eyes) were enrolled in this cross-sectional study. RNFL thickness was measured by both VCC and ECC techniques, and the visual field was examined by HVFA with 24-2 full-threshold program. The relationships between RNFL measurements in superior and inferior sectors and corresponding retinal mean sensitivity were sought globally and regionally with linear regression analysis in each group. Coefficients of the determination were calculated and compared between VCC and ECC techniques. RESULTS: In eyes with ABP, R2 values for the association between SLP parameters and retinal sensitivity were 0.06-0.16 with VCC, whereas they were 0.21-0.48 with ECC. The association of RNFL thickness with retinal sensitivity was significantly better with ECC than with VCC in 5 out of 8 regression models between SLP parameters and HVF parameters (P<0.05). CONCLUSIONS: The strength of the structure-function association was higher with ECC than with VCC in eyes with ABP, which suggests that the ECC algorithm is a better approach for evaluating the structure-function relationship in eyes with ABP.

The Relationship Between Parameters Measured by Optical Coherence Tomography and Visual Field Indices

PURPOSE: To evaluate the diagnostic ability of optic disc topographic parameters and the retinal nerve fiber layer (RNFL) thickness parameter measured by optical coherence tomography (OCT) and to determine the association of these structural parameters with visual field indices. METHODS: Fifty-six glaucomatous eyes and 65 healthy control eyes were enrolled in this retrospective cross-sectional study. Each subject had a 24-2 full threshold test on a Humphrey visual field analyzer and an optical coherence tomographic evaluation. The parameters from the fast RNFL thickness algorithm and the fast optic disc algorithm were analyzed by an ROC curve, and we sought to determine the association of these parameters with visual field indices by linear and logarithmic regression. RESULTS: The area under the receiver operating characteristic curve (AUROC) value of the fast optic disc algorithm parameters ranged from 0.78 to 0.79 and that of the fast RNFL thickness algorithm parameters ranged from 0.74 to 0.81. The associations between the parameters from the fast optic disc algorithm and from the fast RNFL thickness algorithm with visual field indices were statistically significant (P<0.001). CONCLUSIONS: The fast optic disc algorithm and the fast RNFL algorithm revealed comparable diagnostic ability in discriminating glaucoma and significant associations with visual field indices.

Diagnostic Ability of Scanning Laser Polarimetry with Enhanced Corneal Compensation in the Eye with Typical and Atypical Retadation Pattern

PURPOSE: To investigate the relationship between the SLP-VCC parameters and the SLP-ECC parameters in the eyes with typical retardation pattern (TRP) and atypical retardation pattern (ARP), and the sensitivities and specificities of the SLP-VCC parameters and the SLP-ECC parameters in the eye with TRP and ARP. METHODS: In this prospective study, 72 eyes with TRP images (30 glaucomatous and 42 normal eyes) and 53 eyes with ARP images (28 glaucomatous and 25 normal eyes) were recruited. For each group, we analyzed relationship between each parameters of GDx-VCC and GDx-ECC and the diagnostic ability of GDx-ECC by using the ROC curve. RESULTS: In the eyes with TRP, TSNIT average was significantly lower by GDx-ECC than GDx-VCC in the control group. Inferior average was significantly higher by GDx-ECC than GDx-VCC in both glaucomatous and normal group. TSNIT standard deviation was significantly higher by GDx-ECC than GDx-VCC in both groups. NFI was significantly lower by GDx-ECC than GDx-VCC in both groups. TSS (typical scan score) was significantly higher by GDx-ECC than GDx-VCC in both groups. In the eyes with ARP, TSNIT average was significantly lower by GDx-ECC than GDx-VCC in both groups. Superior and Inferior average was not different between GDx-ECC and GDx-VCC. TSNIT standard deviation was significantly higher by GDx-ECC than GDx-VCC in both groups. NFI was not different between groups. TSS was significantly higher by GDx-ECC than GDx-VCC in both groups. Comparison of ROC curve for the SLP parameters revealed no difference between VCC and ECC. TSNIT standard deviation, however, showed relatively high value in GDx-ECC compared with GDx-VCC. CONCLUSIONS: GDx-ECC has comparable diagnostic ability in discriminating glaucomatous and normal eyes with GDx-VCC and TSNIT standard deviation by the GDx-ECC algorithm could be a useful parameter in discriminating glaucomatous and normal eyes.

Comparison of Retinal Nerve Fiber Layer Measurements between NTG and HTG using GDx-VCC

PURPOSE: To compare quantitative polarimetric measurements in eyes with NTG and HTG using GDx-VCC. Both groups were matched by age and glaucoma stage based on the Humphrey visual field test. METHODS: We retrospectively reviewed the records of 146 patients who underwent Humphrey field analysis (HFA) and GDx-VCC. We compared outcomes of retinal nerve fiber layer (RNFL) parameters among the three groups by ANOVA and between each pair of groups using the Tukey-Kramer Post-Hoc test. We also evaluated the sensitivity and specificity of GDx-VCC in detecting glaucoma in each group. RESULTS: The mean age and HFA mean deviation (MD) were 55.6+/-9.5 years and -0.8+/-1.5 dB in 47 control patients, 59.4+/-9.0 years and -5.77+/-4.38 dB in 49 NTG patients, and 59.4+/-11.7 years and -8.09+/-6.77 dB in 51 HTG patients, respectively. All thickness parameters were lower in HTG patients compared to NTG patients, but there were no significant differences in ratio parameters between age-matched early HTG and NTG patients. The sensitivity of GDx-VCC was significantly higher in both early and total HTG patients compared to the respective groups of NTG patients. CONCLUSIONS: Compared to eyes with NTG, eyes with HTG showed reduced RNFL thickness and ratio parameters when patients were age and visual field matched. GDx-VCC appeared to be more sensitive in detecting RNFL damage in HTG patients.

Scanning Laser Polarimetry Using Variable Corneal Compensation in Detection of Localized Visual Field Defects

PURPOSE: To evaluate the ability of scanning laser polarimetry parameters and a novel deviation-map algorithm to discriminate between healthy and early glaucomatous eyes with localized visual field defects confined in one hemifield. METHODS: In this prospective case-controlled study, 61 glaucomatous eyes with localized visual field defects and 66 normal controls were enrolled. Humphrey field analyzer 24-2 glaucoma hemifield test and scanning laser polarimetry (GDx-VCC ) were used. RESULTS: There were significant differences in the mean parametric values of TSNIT average, superior average, inferior average, and TSNIT SD (P<0.05) between the glaucoma group and normal subjects. The sensitivity of each GDx-VCC variable was as follows: TSNIT average, 47.5%; superior average, 31.1%; inferior average, 47.5%; and TSNIT SD, 24.6% (when abnormal was defined as P<0.05). The overall sensitivities combining each probability scale and severity score at 80%, 90%, and 95% specificity were 90.2%, 72.1%, and 59%, respectively. There was a statistically significant correlation between the GDx-VCC severity score and the visual field severity score (P<0.05). CONCLUSIONS: GDx-VCC parameters may not be sufficiently sensitive to detect glaucomatous patients with localized visual field damage. Our algorithm using the GDx-VCC deviation map may enhance the understanding of GDx-VCC in terms of the locality, deviation size, and severity of localized RNFL defects in eyes with localized visual field loss.

Correlation Between Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry in Glaucoma Suspects and Glaucomatous Eyes

The aim of this study was to determine the relationship between the frequency doubling technology (FDT) screening algorithm and parapapillary retinal nerve fiber layer (RNFL) thickness in the eyes of glaucoma suspects and patients with open angle glaucoma. FDT C20-1 screening program and a scanning laser polarimetry (SLP) system (GDx-NFA) was used to assess 53 glaucomatous eyes, 53 glaucoma suspects and 36 normal control eyes. In glaucomatous eyes, there were correlations between the FDT the screening algorithm and RNFL retardation values in several polarimetric indices, most significantly "inferior thickness" (r = -0.321, P = 0.029). In the eyes of glaucoma suspects, however, we observed no correlation between the FDT results and RNFL retardation values (r = 0.080, P > 0.05, "inferior thickness"). In glaucomatous eyes, the abnormal scores obtained with FDT screening program correlated negatively with RNFL retardation values, as measured by SLP. Despite poor correlation between the FDT abnormal score and RNFL retardation value in glaucoma suspects, detection of abnormality using the FDT screening protocol may aid in the assessment of early glaucomatous structural damage.

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.

The Relationship between the Duration of IOP Elevation during LASIK and Nerve Fiber Layer Thickness Measured by GDx(R)

PURPOSE: To determine the effect of temporary intraocular pressure (IOP) elevation during laser in situ keratomileusis (LASIK) on retinal nerve fiber layer measurement by scanning laser polarimetry in a clinical trial. METHODS: The duration of IOP elevation was recorded during LASIK and scanning laser polarimetry (GDx(R) Retinal Nerve Fiber Analyzer. Laser Diagnostic Technologies, Inc, San Diego, California) measurements were performed in 60 eyes of 30 consecutive patients before and after the LASIK procedure. RESULTS: The mean duration of IOP elevation during LASIK was 27.2+/-4.5 seconds. The mean retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry were 73.2+/-12.8 micro meter preoperatively, 65.6+/-12.7 at postoperative 1 month and 66.0+/-9.8 micro meter at postopertive 3 months. The mean postoperative 1 month and 3 months values showed significantly reduced RNFL thickness. But, there was no relationship between the duration of IOP elevation and the amount of nerve fiber layer thickness reduction. (R2=0.064, p=0.627) Furthermore, there were no interval change between the retardation values of postoperative 1 month and 3 months (p=0.706). CONCLUSIONS: There was no relationship between the duration of IOP elevation during LASIK and the postoperative reduction of RNFL thickness measured by scanning laser polarimetry. When using scanning laser polarimetry as a helpful diagnostic and follow-up tool for glaucoma, care should be taken in the interpretation of the result after LASIK procedure. If a comparison is likely to be needed in the future, this image should be obtained after the LASIK procedure to set the postoperative baseline.

Interocular comparison of nerve fiber layer thickness and its relation with optic disc size in normal subjects

We conducted an investigation of the relation between RNFL thickness and optic disc size along with an interocular comparison of optic disc size, RNFL thickness, and RNFL density in healthy subjects. A total of 64 normal eyes from 32 Korean volunteers were enrolled in this study. A GDx Nerve Fiber Analyzer with software version 2.0.09 was used to image all subjects. Optic disc size was measured by pi x (horizontal radius) x (vertical radius). The RNFL density of each quadrant was calculated by dividing each quadrant integral by the total integral. Optic disc size was positively correlated with the total RNFL thickness (r = 0.615, p < 0.01). Optic disc size and RNFL density were inversely related in the superior quadrant (r = -0.248, p < 0.05). There was a significant positive correlation between optic disc size and RNFL density in the nasal quadrant (r = 0.439, p < 0.01) and the temporal quadrant to a certain degree. A significant positive correlation was found between the right and left eyes in terms of total RNFL thickness in and that of each quadrant. Interocular RNFL density was positively correlated in both the temporal and nasal quadrants. These findings must be considered when one evaluates and compares RNFL measurements between two eyes as is often the case where both eyes are usually affected in the course of glaucomatous RNFL damage.

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.