Reproducibility of retinal nerve fiber thickness measurements using the stratus OCT in normal and glaucomatous eyes

PURPOSE: To determine the reproducibility of Stratus Optical Coherence Tomography (OCT) retinal nerve fiber layer (RNFL) measurements around the optic nerve in normal and glaucomatous eyes. METHODS: One eye was chosen at random from 88 normal subjects and 59 glaucomatous subjects distributed among mild, moderate, and severe glaucoma, determined by visual field testing. Subjects underwent six RNFL thickness measurements performed by a single operator over a 30-minute period with a brief rest between sessions. Three scans were taken with the high-density Standard RNFL protocol, and three were taken with the Fast RNFL protocol, alternating between scan protocols. RESULTS: Reliability, as measured by intraclass correlation coefficient (ICC), was calculated for the overall mean RNFL thickness and for each quadrant. The ICC for the mean Standard RNFL thickness (and lower 95% confidence interval [CI]) in normal and glaucomatous eyes was 0.97 (0.96 CI) and 0.98 (0.97 CI), respectively. The ICC for the mean Fast RNFL thickness in normal and glaucomatous eyes was 0.95 (0.93 CI) and 0.97 (0.95 CI), respectively. Quadrant ICCs ranged between 0.79 and 0.97, with the nasal quadrant being the least reproducible of all four quadrants, using either the Standard or Fast RNFL program. The test-retest variability ranged from 3.5 microm for the average RNFL thickness measurements in normal eyes to 13.8 microm for the nasal quadrant measurements in glaucomatous eyes, which appeared to be the most variable. CONCLUSIONS: Reproducibility of RNFL measurements using the Stratus OCT is excellent in normal and glaucomatous eyes. The nasal quadrant appears to be the most variable measurement. Standard RNFL and Fast RNFL scans are equally reproducible and yield comparable measurements. These findings have implications for the diagnosis of glaucoma and glaucomatous progression.     

Correlation of Peripapillary Choroidal Thickness and Retinal Nerve Fiber Layer Thickness in Normal Subjects and in Patients with Glaucoma

Purpose: This study was designed to compare the normal and glaucomatous eyes regarding retinal nerve fiber layer (RNFL) thickness and peripapillary choroidal thickness (PCT), and to investigate the correlation of RNFL thickness and PCT. Subjects and Methods: Subjects were selected as a convenience sample of those from a tertiary referral practice of glaucoma. Thirty-two glaucomatous eyes were accepted as group 1; 30 normal eyes were accepted as group 2. Groups were compared for RNFL thickness and PCT. Correlations of RNFL thickness and PCT were assessed for each peripapillary location. Results: Mean inferior and superior RNFL thickness in group 1 were significantly lower than the control group; mean thicknesses of temporal and nasal quadrants were not different in the two groups. Mean PCT at 500 µm distance in the inferior, at 1500 µm distance in the superior, at 500, 1000, and 1500 µm distance in the temporal, and at 1000 and 1500 µm distance in nasal quadrants were found to be significantly thinner in the glaucoma group compared with the control group. Retinal nerve fiber thickness was strongly correlated with PCT at all points of inferior quadrants at 500 µm distance in the superior. There was no correlation between RNFL thickness and PCT at any point in the control group. Conclusion: Peripapillary choroidal thickness was thinner in glaucomatous eyes compared with normal eyes. Correlation of PCT and RNFL thickness found in patients with glaucoma did not exist in normal subjects.     

Evaluation of the glaucomatous damage on retinal nerve fiber layer thickness measured by optical coherence tomography

PURPOSE: To evaluate the relationship between visual field and retinal nerve fiber layer (RNFL) thickness measured by optical coherent tomography (OCT) and to assess the diagnostic ability of OCT to distinguish between early glaucomatous or glaucoma-suspect eyes from normal eyes. DESIGN: Retrospective, non-randomized, cross-sectional study. METHODS: A total of 160 eyes of 120 normal Japanese adults, 23 eyes of 16 patients with ocular hypertension, 38 eyes of 35 glaucoma-suspect patients, and 237 glaucomatous eyes of 140 glaucoma patients were enrolled in the study. The glaucoma group included 89 early glaucomatous eyes. Thickness of the RNFL around the optic disk was determined with three 3.4-mm diameter circle OCT scans. Average and segmental RNFL thickness values were compared among all groups. The correlation between mean deviation and RNFL thickness in glaucomatous eyes was also analyzed. Receiver operating characteristic (ROC) curve area was calculated to discriminate normal eyes from early glaucomatous or glaucoma-suspect eyes. RESULTS: A significant relationship existed between the mean deviation and RNFL thickness in all parameters excluding the 3-o'clock area. The average RNFL thickness had the strongest correlation in all parameters (r = -0.729, P <.001). Retinal nerve fiber layer thickness at the 7-o'clock inferotemporal segment had the widest areas under the ROC curves in all parameters for early glaucomatous eyes (0.873). CONCLUSIONS: Measurement of RNFL thickness by OCT is useful in detecting early RNFL damage. Furthermore, OCT measurements of RNFL thickness may provide clinically relevant information in monitoring glaucomatous changes.     

Correlations between densitometry of red-free photographs and reflectometry with the scanning laser ophthalmoscope in normal subjects and glaucoma patients

Objective: To compare image measurements of the retina produced by scanning laser ophthalmoscopy with those from red-free photographs (RFP) of the nerve fibre layer.Subjects: The left eyes of 23 subjects (10 normal, 7 glaucoma suspect and 6 glaucomatous) were included in this study.Method: All the eyes were photographed using standard red-free photography, and images of the retina were digitised directly from the SLO.Results: The correlation coefficient for all except three subjects was > 0.45, and the probability (p) that R=0 was < 0.05 in all but 5 eyes.Conclusions: The data indicate that variations in retinal surface reflectivity as measured by the SLO are similar to those recorded on negative film during RFP. This further suggests that the SLO can be useful for making objective measurements of the RNFL, without the intermediate and variable steps of photography.Abbreviations RFP red-free photographs - RNFL retinal nerve fibre layer - SLO scanning laser ophthalmoscope     

Correlation between optic nerve head parameters and retinal nerve fibre layer thickness measured by spectral-domain optical coherence tomography in myopic eyes

Background: To evaluate the correlation between optic nerve head parameters and retinal nerve fiber layer thickness measured by Cirrus HD spectral‐domain optical coherence tomography (Cirrus HD‐OCT; Carl Zeiss Meditec) in healthy myopic eyes. Design: Cross‐sectional study. Participants: One hundred and sixty‐one right eyes from 161 healthy young myopic subjects. Methods: Optic nerve head parameters and retinal nerve fiber layer thickness were measured with the Cirrus HD‐OCT. The distance between optic disc margin and scan circle (disc margin‐to‐scan distance) was measured on the Cirrus HD‐OCT en‐face optic nerve head image with aid of National Institutes of Health ImageJ image‐analysis software (developed by Wayne Rasbands, National Institutes of Health, Bethesda, MD). Main Outcome Measures: The correlations among optic nerve head parameters, retinal nerve fibre layer thickness and the disc margin‐to‐scan distance were evaluated with and without adjustment of the magnification effect. Results: Without correction of the magnification effect, the thicker average retinal nerve fiber layer was correlated with greater rim area and lower degree of myopia (P < 0.001). When the magnification effect was corrected, thicker average retinal nerve fibre layer was associated with greater disc area and greater rim area in univariate and multivariate analyses (P ≤ 0.028); however, degrees of myopia and the disc margin‐to‐scan distance were not significantly associated with average RNFL thickness (P ≥ 0.104). Conclusions: Thicker average retinal nerve fibre layer thickness was associated with greater rim and disc areas. Disc margin‐to‐scan distance was not significantly correlated with average retinal nerve fibre layer thickness in healthy myopic eyes.     

Comparison of retinal nerve fibre layer thickness and visual field loss between different glaucoma groups

BACKGROUND/AIMS: Scanning laser polarimetry (SLP) uses a confocal scanning laser ophthalmoscope with an integrated polarimeter to evaluate the thickness of the retinal nerve fibre layer (RNFL). The aim of this study was to verify the ability of the SLP to detect differences in RNFL thickness between normal and glaucomatous eyes and between glaucomatous eyes subdivided in groups by the severity of visual field damage. METHODS: This was a cross sectional retrospective study. The charts of 40 healthy subjects and 68 glaucoma patients who underwent complete ophthalmological examination, optic disc stereophotography, peripapillary, and macular SLP imaging were reviewed. The right eye of subjects eligible for the study was enrolled. Only eyes with SLP examinations indicating a minimised effect of anterior segment birefringence based on macular image were included. The ability of retardation parameters to discriminate between healthy and glaucomatous eyes was evaluated. Based on visual field loss, glaucoma patients were subdivided in three subgroups (early, moderate, and severe). RNFL thickness between healthy control group and glaucoma subgroups was compared. RNFL thickness and visual field loss correlation was evaluated. RESULTS: There was a significant difference in superior and inferior maximum RNFL thickness between normal and glaucomatous eyes (p<0.001). With these two parameters, the area under receiver operator characteristic curve was 0.75 and 0.74, respectively. Superior and inferior RNFL thickness was significantly different between healthy control group and all glaucoma subgroups (p<0.001) and between glaucoma subgroups (p<0.05), except for early and moderate glaucoma subgroups (p>0.05). Linear regression showed a weak correlation between RNFL thickness and visual field loss. CONCLUSION: These results suggest that once visual field loss is established, smaller reductions in the RNFL thickness detected by SLP are necessary for a given reduction of mean defect value.     

Optical coherence tomography measurement of the retinal nerve fiber layer in normal and juvenile glaucomatous eyes

The aim of this study was to quantitatively assess and compare the thickness of the retinal nerve fiber layer (RNFL) in normal and glaucomatous eyes of children using the optical coherence tomograph. The mean RNFL thickness of normal eyes (n=26) was compared with that of glaucomatous eyes (n=26). The eyes were classified into diagnostic groups based on conventional ophthalmological physical examination, Humphrey 30-2 visual fields, stereoscopic optic nerve head photography, and optical coherence tomography. The mean RNFL was significantly thinner in glaucomatous eyes than in normal eyes: 95+/-26.3 and 132+/-24.5 microm, respectively. More specifically, the RNFL was significantly thinner in glaucomatous eyes than in normal eyes in the inferior quadrant: 87+/-23.5 and 122+/-24.2 microm, respectively. The mean and inferior quadrant RFNL thicknesses as measured by the optical coherence tomograph showed a statistically significant correlation with glaucoma. Optical coherence tomography may contribute to tracking of juvenile glaucoma progression.     

Peripapillary fundus perimetry in eyes with glaucoma

AIMS: To evaluate, with fundus perimetry, the peripapillary differential light threshold (DLT) in eyes with glaucoma and ocular hypertension (OHT), and compare it with peripapillary retinal nerve fibre layer (RNFL) thickness. METHODS: 35 glaucomatous, 29 OHT and 24 control eyes were included. Peripapillary DLT at 1 degrees from the optic nerve head was quantified with fundus perimetry; peripapillary RNFL thickness was measured over the same area by optical coherence tomography. RESULTS: Mean (SD) peripapillary DLT was 19.2 (1.7), 17.6 (4.2) and 10.1 (6.9) dB in control, OHT and glaucomatous eyes, respectively (p<0.001). Mean (SD) RNFL thickness was 98.4 (35.3), 83.9 (35.1) and 55.8 (28.2) microm, respectively (p<0.001). Mean peripapillary DLT showed higher sensitivity and specificity in differentiating the three groups compared with RNFL thickness. CONCLUSION: Progressive, significant reduction of peripapillary DLT was documented in OHT and glaucomatous eyes compared with controls (p<0.001). DLT reduction parallels RNFL reduction.     

Interpretation of RNFLT values in multiple sclerosis‐associated acute optic neuritis using high‐resolution SD‐OCT device

Purpose: Optical coherence tomography (OCT) has emerged as the technique of choice in measuring the retinal nerve fibre layer (RNFL) quantitatively. It is suggested that RNFL reduction may correlate with lesion burden and diffuse axonal degeneration in the whole CNS of patients with multiple sclerosis (MS). However, RNFL changes because of optic neuritis (ON) must be taken into account. Methods: Twenty‐three patients with acute ON (46 eyes) associated with clinical definite MS (23 ON eyes, 23 fellow eyes) and 23 sex‐ and age‐matched healthy controls were studied. Retinal nerve fibre layer thickness (RNFLT) was measured at baseline, using a high‐resolution spectral domain OCT (SD‐OCT) applying circular, peripapillary OCT scans with a novel eye‐tracking mechanism. Results: The internal OCT software was able to identify RNFL atrophy in three out of five of the acute ON eyes and one out of four of the fellow eyes with previous ON episodes. Retinal nerve fibre layer thickness of two ON (8.7%) and five fellow eyes (21.7%) was overestimated, thus located within the 95% and 5% confidence interval of the company standard values (not marked pathologic). In contrast, our comparison with age‐ and sex‐matched controls revealed RNFL atrophy suggestive of prior, clinically silent RNFL loss in ON and fellow eyes (30.4%). Conclusion: Retinal nerve fibre layer thickness measurements at a single time‐point seem to have a limited role in detecting prior clinically silent optic nerve injury. Our data suggest that affected eyes should be compared with the fellow eyes and a sufficient number of age‐ and sex‐matched controls to allow the detection of even subtle RNFL changes at baseline. The role of OCT for disease monitoring of MS must be evaluated in detail, as ON is often the initial symptom of MS.     

Comparison of algorithms for detection of localised nerve fibre layer defects using scanning laser polarimetry

AIMS: To evaluate different algorithms used to analyse retinal nerve fibre layer thickness (RNFL) data obtained by scanning laser polarimetry, in order to compare their relative abilities to discriminate between patients with glaucomatous localised nerve fibre layer defects and normal subjects. METHODS: 48 eyes of 48 glaucomatous patients with localised RNFL defects and 53 eyes of 53 healthy subjects were included in this study. The localised RNFL defects were identified by RNFL photography and/or slit lamp biomicroscopic examination. All patients were submitted to RNFL examination using scanning laser polarimetry (GDx nerve fibre analyser, Laser Diagnostic Technologies, Inc, San Diego, CA, USA). Three methods of analysis of polarimetry data were used: GDx software provided parameters; RNFL thickness measurements in 16 equal sectors around the optic disc (sectoral analysis); and Fourier analysis of the curve of distribution of RNFL thickness measurements. Linear discriminant functions were developed to assess sensitivity and specificity of the sectoral based analysis and Fourier analysis and were compared to the GDx parameters. In addition, areas under the receiver operating characteristic (ROC) curves were compared. RESULTS: At a fixed specificity of 91%, the sensitivity of the linear discriminant function from sectoral data (LDF sectoral) was 81%, with an area under the ROC curve of 0.93. The linear discriminant function from Fourier measures had a comparable performance, with an area under the ROC curve of 0.93, and sensitivity of 71% for specificity at 91%. At the same specificity, the sensitivities of the GDx software provided parameters ranged from 15% to 40%. The areas under the ROC curves for the LDF sectoral and LDF Fourier were significantly greater than the ROC curve area for the single best GDx parameter. CONCLUSION: The sectoral based analysis and the Fourier analysis of RNFL polarimetry data resulted in an improved detection of eyes with glaucomatous localised nerve fibre layer defects compared to the GDx software provided parameters.     

Specificity and sensitivity of glaucoma detection in the Japanese population using scanning laser polarimetry.

AIMS: To investigate the usefulness of the scanning laser polarimeter (GDx; GDx Nerve Fiber Analyzer) for glaucoma detection in the Japanese population, and to investigate the difference in the thickness of retinal nerve fibre layer (RNFL) between normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). METHODS: 69 eyes of 69 normal subjects and 115 eyes of 115 chronic open angle glaucoma patients (60 NTG and 55 POAG patients) were studied. The thickness of RNFL was measured with GDx. An eye was diagnosed as glaucomatous, if at least one original GDx variable showed p <5%. The difference in thickness of RNFL between the NTG and POAG groups was then investigated. RESULTS: 46 normal eyes (66.7%) were diagnosed as not glaucomatous (no variables showing p <5%), and 93 glaucomatous eyes (46 NTG and 47 POAG eyes) (80.9%) were diagnosed as glaucomatous. Actual values of average thickness, ellipse average, superior average, and superior integral were significantly lower in the POAG group than those in the NTG group. CONCLUSIONS: New variables which elucidate focal RNFL defects or early changes are needed to improve the moderate detection ability found in this present study. The pattern of the change in RNFL may differ in NTG and POAG groups.     

Quantification of the retinal nerve fibre layer thickness in normal Indian eyes with optical coherence tomography

PURPOSE: To quantitatively assess the normative values for peripapillary retinal nerve fibre layer (RNFL) thickness with Optical Coherence Tomography (OCT 3) in Indian subjects. METHODS: The peripapillary retinal nerve fibre layer of 146 normal subjects was imaged on OCT 3 in this cross-sectional study. Thickness of the RNFL around the disc was determined with three 3.4 mm diameter circle OCT scan. The RNFL thickness was measured in four quadrants; superior, nasal, inferior and temporal. The data was analysed using SAS commercial statistical software. Influence of age and gender was evaluated on various measured parameters using unpaired t test, one-way analysis variance (ANOVA) and Pearson's correlation coefficient. RESULTS: One hundred and forty six eyes of 146 patients, 84 males and 62 females were studied. The average RNFL thickness in the sample population under study was 104.27 +/- 8.51 (95% CI 87.25-121). The RNFL was thickest in the inferior quadrant, followed by the superior quadrant, and progressively less in nasal and temporal quadrant. The difference between inferior and superior quadrants was not statistically significant. Age had a significant negative correlation with average RNFL thickness (r = -0.321, P = 0.000) and with average superior (r = -0.233, P = 0.005) and average inferior RNFL thickness (r = -0.234, P = 0.004). There was no effect of gender on various RNFL thickness parameters. CONCLUSIONS: RNFL thickness is significantly correlated with age, but not with gender. This normative database of RNFL thickness with OCT in Indian eyes is similar to previously reported values in normal Asian eyes.     

Comparison of retinal nerve fibre layer thickness with visual evoked potential and visual field in patients with multiple sclerosis

Background: To evaluate retinal nerve fibre layer thickness and to compare results with visual evoked potentials and visual field in patients with multiple sclerosis. Design: A prospective, case‐control study, university hospital setting. Participants: Seventy‐three eyes of 37 multiple sclerosis patients and 74 eyes of 37 healthy subjects. Methods: All patients underwent a complete neurological and ophthalmological examination and peri‐papillary retinal nerve fibre layer thickness was evaluated using scanning laser polarimetry (GDx). Furthermore, visual evoked potential and visual field testing were performed. Main Outcome Measures: The χ² test, Student's t‐test, Mann–Whitney U‐test and Pearson's correlation coefficient analysis of the GDx, visual evoked potential and visual field testing parameters. Results: GDx measurements showed significantly more retinal nerve fibre layer damage in the patients than in the control groups. Comparison of the GDx parameters between patients with optic neuritis and non‐optic neuritis demonstrated a statistically significant difference in symmetry (P = 0.046) and superior/nasal parameters (P = 0.009). A correlation was found between the number, superior and inferior ratio parameters, and P100 amplitude obtained with visual evoked potential in patients with non‐optic neuritis. Additionally, there was a correlation between the number, inferior ratio and superior/nasal parameters, and the mean deviation of visual field in the non‐optic neuritis group. Conclusions: For retinal nerve fibre layer thickness measurements in multiple sclerosis patients, the GDx, along with other techniques, such as visual evoked potential, can be used as a diagnostic and follow‐up criterion, particularly in patients without optic neuritis.     

The retinal nerve fibre layer thickness in glaucomatous hydrophthalmic eyes assessed by scanning laser polarimetry with variable corneal compensation in comparison with age‐matched healthy children

Purpose: To compare the thickness of the retinal nerve fibre layer (RNFL) in hydrophthalmic glaucomatous eyes in children with age‐matched healthy controls using scanning laser polarimetry with variable corneal compensation (GDxVCC). Methods: Twenty hydrophthalmic eyes of 20 patients with the mean age of 10.64 ± 3.02 years being treated for congenital or infantile glaucoma were included in the analysis. Evaluation of RNFL thickness measured by GDxVCC in standard Temporal‐Superior‐Nasal‐Inferior‐Temporal (TSNIT) parameters was performed. The results were compared to TSNIT values of an age‐matched control group of 120 healthy children published recently as referential values. The correlation between horizontal corneal diameter and RNFL thickness in hydrophthalmic eyes was also investigated. Results: The mean ± SD values in TSNIT Average, Superior Average, Inferior Average and TSNIT SD in hydrophthalmic eyes were 52.3 ± 11.4, 59.7 ± 17.1, 62.0 ± 15.6 and 20.0 ± 7.8 μm, respectively. All these values were significantly lower compared to referential TSNIT parameters of age‐matched healthy eyes (p = 0.021, p = 0.001, p = 0.003 and p = 0.018, respectively). A substantial number of hydrophthalmic eyes laid below the level of 5% probability of normality in respective TSNIT parameters: 30% of the eyes in TSNIT average, 50% of the eyes in superior average, 30% of the eyes in inferior average and 45% of the eyes in TSNIT SD. No significant correlation between enlarged corneal diameter and RNFL thickness was found. Conclusions: The mean values of all standard TSNIT parameters assessed using GDxVCC in hydrophthalmic glaucomatous eyes in children were significantly lower in comparison with referential values of healthy age‐matched children.     

频域光学相干断层扫描在视网膜神经纤维层厚度测量中的应用

目的应用频域光学相干断层扫描（OCT）测量非青光眼受试者和青光眼患者的视盘周视网膜神经纤维层（RNFL）厚度,并对测量结果进行重复性检验。方法非青光眼受试者和青光眼患者各30例纳入研究,随机选取受试者一侧眼的数据进行统计分析。应用Spectralis OCT对每位受试者进行视盘周RNFL厚度测量,应用“随诊”模式进行3次扫描。计算出受试者内部标准筹（Sw）、变异系数（CV）和同类相关系数（ICC）,以评价该仪器测量的可重复性。应用Spearman秩相关系数分析评估每位受试者RNFL厚度平均数值与其3次测量的标准差之间的天系。结果非青光眼受试者的CV数值范围为1．44％（全周厚度平均值）～2．58％（颞侧象限）,青光眼患者的CV为1．73％（全周）～3．24％（颞侧象限）;非青光眼受试者的ICC数值范围为0．977（颞侧象限）～0．990（鼻下45。扇形区）,青光眼患者的ICC数值范围为0．981（颞侧象限）～0．997（下方象限）;非青光眼受试者的Sw为1．33μm（全周）～2．36μm（颞上45°扇形区）,青光眼患者的Sw为1．13μm（全周）～2．26μm（鼻上45。扇形区）;RNFL厚度数值与测量变异性间无明显相关性（P〉0．05）。结论高速扫描和眼跟踪系统使Spectralis OCT在测量非青光眼受试者和青光眼患者的视盘周RNFL厚度均有良好的可重复性,是青光眼长期随诊中对于其结构性损害可信赖的影像学检查技术。     

Comparison of glaucomatous parameters in normal, ocular hypertensive and glaucomatous eyes using optical coherence tomography 3000

This study was performed to evaluate optic disc appearance, retinal nerve fiber layer (RNFL) thickness, and macular thickness in normal, ocular hypertensive (OHT) and glaucomatous eyes using optical coherence tomography (OCT) 3000. One hundred fifty-eight eyes of 167 consecutive subjects were enrolled: 60 normal, 53 OHT, and 54 glaucomatous. OCT topographic parameters of cup diameter, cup area, rim area, and cup/disc area ratio were significantly less in OHT eyes than in normal eyes and were significantly less in glaucomatous eyes than in normal and OHT eyes. RNFL was significantly thinner in OHT eyes than in normal eyes in the inferior quadrant, and in glaucomatous eyes than in OHT and normal eyes in the mean and for all four quadrants. Macular thickness was significantly thinner in glaucomatous eyes than in OHT and normal eyes throughout all subdivisions. Optic disc parameters, and RNFL and macular thickness measurements made with OCT may be useful in the clinical assessment of glaucoma.     

Comparison of the influence of cataract and pupil size on retinal nerve fibre layer thickness measurements with time-domain and spectral-domain optical coherence tomography

Background: To investigate and compare the effect of cataract and pupil size on retinal nerve fibre layer (RNFL) thickness measurements using spectral‐domain optical coherence tomography (Cirrus OCT) and time‐domain OCT (Stratus OCT). Design: Prospective, hospital‐based study. Participants: Twenty‐five eyes from 25 normal subjects undergoing cataract surgery. Methods: Three retinal nerve fibre layer (RNFL) thickness measurements were taken before and after dilation, preoperatively and postoperatively, using Cirrus 200 × 200 Optic Disc Scan and Stratus Fast RNFL Scan. Main Outcome Measures: Linear regression, intraclass correlation coefficient (ICC) and coefficient of variation analysis. Results: Cataract removal caused significant increase in RNFL measurements in both modalities (Cirrus P < 0.02; Stratus P < 0.001). There was no significant difference in the increase in measurements between the two machines. Pupil dilation had variable and non‐statistically significant effect in both (P > 0.05). ICC showed excellent reproducibility with Cirrus OCT after mydriasis, preoperatively (ICC = 0.78–0.90) and postoperatively (ICC = 0.90–0.97), but poor reproducibility before mydriasis (P < 0.75). Stratus OCT achieved excellent reproducibility after cataract removal both before (ICC = 0.86–0.96) and after mydriasis (ICC = 0.92–0.95), but poor reproducibility before cataract surgery (P < 0.75). Conclusions: Cataracts, not pupil size, cause significant underestimation of RNFL measurements in both Cirrus and Stratus OCT. The extent of influence exerted does not appear different between the two instruments. Reproducibility of each machine appears to be affected differently. Mydriasis is required to achieve excellent reproducibility with Cirrus OCT, and media clarity is required with Stratus OCT.     

Evaluation of retinal nerve fiber layer thickness in the area of apparently normal hemifield in glaucomatous eyes with optical coherence tomography

PURPOSE: The authors investigated the correlation between visual field defects detected by automated perimetry and the thickness of the retinal nerve fiber layer measured with optical coherence tomography, and examined whether there is a decrease in retinal nerve fiber layer thickness in the apparently normal hemifield of glaucomatous eyes. PATIENTS AND METHODS: Forty-one patients with glaucoma and 41 normal control subjects were included in this study. Statistical correlations between the sum of the total deviation of 37 stimuli of each hemifield and the ratio of decrease in retinal nerve fiber layer thickness were evaluated. The statistical difference between the retinal nerve fiber layer thickness of the apparently normal hemifield in glaucomatous eyes and that of the corresponding hemifield in normal subjects was also evaluated. RESULTS: There was a statistically significant correlation in the sum of the total deviation and retinal nerve fiber layer thickness decrease ratio (superior hemifield, P = 0.001; inferior hemifield, P = 0.003). There was no significant decrease in retinal nerve fiber layer thickness in the area that corresponded to the normal visual field in the hemifield defect with respect to the horizontal meridian in glaucomatous eyes (superior side, P = 0.148; inferior side, P = 0.341). CONCLUSIONS: Optical coherence tomography was capable of demonstrating and measuring retinal nerve fiber layer abnormalities. No changes in the retinal nerve fiber layer thickness of the apparently normal hemifield were observed in glaucomatous eyes.     

Correlation between retinal nerve fibre layer thickness and retinal sensitivity

Purpose: To evaluate the relationship between retinal nerve fibre layer (RNFL) thickness measured by optical coherence tomography (OCT) and light threshold values obtained with the Micro Perimeter 1 (MP1). Methods: Forty‐nine normal subjects and 37 glaucoma patients were included. Thickness of the RNFL around the optic disc was measured with Stratus OCT scans, and static threshold perimetry was performed with the MP1 at the same visit. Total average and mean 12‐clock‐hour RNFL thickness were measured with Stratus OCT. An automated 4‐2‐1 staircase strategy with Goldmann III stimuli was used for MP1. The correspondence between Stratus OCT and MP1 RNFL measurements in each clock‐hour was best fit by a second‐order polynomial. Results: Average RNFL thickness in the normal group was significantly higher than that in the glaucoma group in each clock hour. Comparing the normal and glaucomatous groups, retinal sensitivity differed significantly at 6, 7, 8 and 11 o’clock. In these regions, structure–function relationships were generally stronger than in other regions. Conclusions: Structure–function associations may be strong when loss of nerve fibres is severe. However, significant reduction in retinal sensitivity does not emerge until the atrophy of nerve fibres is severe.     

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.