Early detection of thinning of retinal nerve fiber layer in glaucomatous eyes by optical coherence tomography 3000: analysis of retinal nerve fiber layer corresponding to the preserved hemivisual field

The retinal nerve fiber layer (RNFL) thickness was measured with the optical coherence tomography using version 3.0 software (OCT3000) in 153 eyes of 153 normal subjects. The mean of the average RNFL thickness over the entire 360 degrees in the control group was 92.5 +/- 12.9 microm which was significantly thinner than the normative data of 95.9 +/- 11.4 microm included with the OCT3000 (p < 0.01). The RNFL thickness decreased with increasing age (p < 0.01, r = -0.395). The RNFL thickness was also measured in 53 eyes of 53 patients with glaucoma whose superior (13 eyes) or inferior (40 eyes) perimetric hemifields were normal. Only the RNFL thickness corresponding to the preserved perimetric hemifields were measured by OCT3000 and scanning laser ophthalmoscopy (SLO). The RNFL thickness in the superior and inferior 30 degrees sectors, the maximum and average RNFL thickness in the superior (S(max) and S(avg)), and inferior quadrants (I(max) and I(avg)) were analyzed.The S(max), S(avg), I(max), I(avg), and the RNFL thickness in the superior (p < 0.05), superotemporal and inferotemporal sectors (p < 0.01) in the glaucoma patients without a nerve fiber layer defect (SLO) were significantly thinner than in the control subjects in same age. OCT3000 measurements showed that the RNFL thickness in glaucomatous eyes with normal perimetric visual fields and SLO was significantly thinner than the RNFL thickness in normal eyes.     

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.     

Nerve fiber layer thickness in glaucoma patients with asymmetric hemifield visual field loss

PURPOSE: To investigate the presence of retinal nerve fiber layer (RNFL) thinning and determine the relationship between RNFL thickness and visual field sensitivity loss in glaucoma patients with asymmetric hemifield visual field loss. PATIENTS AND METHODS: Thirty glaucoma patients with asymmetric hemifield visual field loss and 30 normal control subjects were included in the study. RNFL thickness was measured by optical coherence tomography and visual field sensitivity was measured by automated perimetry. Glaucoma patients with advanced visual field loss restricted to 1 hemifield and early or absent glaucomatous field loss in the other hemifield on the basis of the visual field data were included. Visual field sensitivity and mean deviation (MD) were averaged separately in each of the 2 hemifields. The hemifields in each eye were categorized as early (MD>or=-6 dB) and advanced (MD<-6 dB) glaucomatous hemifields. RESULTS: RNFL thickness measurements in corresponding (eg, superior peripapillary quadrant with inferior hemifield) advanced glaucomatous hemifields (59+/-16 microm) were significantly (P<0.001) lower than in corresponding early glaucomatous hemifields (90+/-25 microm). The mean RNFL thickness in corresponding advanced and early glaucomatous hemifields were significantly lower than in normal control subjects (P<0.0001). On the basis of the normative database supplied by optical coherence tomography software, 100% and 43% of eyes had abnormal RNFL thickness in corresponding advanced and early glaucomatous hemifields, respectively. A linear correlation was found between RNFL thickness and MD in the early (r=0.6; P<0.001) and advanced (r=0.5; P=0.007) glaucomatous hemifields. CONCLUSIONS: RNFL thinning was present in corresponding hemifields of glaucomatous eyes with minimal visual field defect and correlated with visual field sensitivity loss. Measurement of RNFL thickness has potential for detection of early nerve fiber loss owing to glaucoma.     

Comparative evaluation of optical coherence tomography in glaucomatous, ocular hypertensive and normal eyes

BACKGROUND: To correlate the findings of optical coherence tomography (OCT) evaluation of retinal nerve fiber layer (RNFL) thickness with visual field changes in glaucomatous, ocular hypertensive and normal eyes. MATERIALS AND METHODS: Thirty consecutive normal, 30 consecutive ocular hypertensive and 30 consecutive glaucomatous eyes underwent a complete ophthalmic examination, including applanation tonometry, disc evaluation, (30-2) Humphrey field analyzer white on white (W/W) perimetry and short- wavelength automated perimetry. Thickness of the RNFL around the optic disc was determined with 3.4 mm diameter-wide OCT scans. Average and segmental RNFL thickness values were compared among all groups. A correlation was sought between global indices of perimetry and RNFL thickness. RESULTS: Of the 90 eyes enrolled (mean age of patients 52.32+/-10.11 years), the mean RNFL thickness was significantly less in ocular hypertensive (82.87+/-17.21 mm; P =0.008 and glaucomatous eyes (52.95+/-31.10 microm; P < 0.001), than in normals (94.26+/-12.36 microm). The RNFL was significantly thinner inferiorly in glaucomatous eyes (64.41+/-43.68 microm; P<0.001). than in normals (120.15+/-14.32 microm) and ocular hypertensives (107.87+/-25.79 microm; P<0.001). Ocular hypertensives had thinner RNFL in the nasal, inferior and temporal quadrants (P<0.001) when compared to normals. Global indices in ocular hypertensives on SWAP showed Mean Deviation (MD) of 5.32+/-4.49, Pattern Standard Deviation (PSD) 3.83+/-1.59 and Corrected Pattern Standard Deviation (CPSD) 2.84+/-1.85. The RNFL thickness could not be significantly correlated with global indices of visual fields in ocular hypertensives. CONCLUSION: Optical coherence tomography is capable of detecting changes at the level of RNFL in ocular hypertensive eyes with normal appearance of discs and W/W perimetry fields.     

光学相干断层成像术对原发性开角型青光眼视网膜神经纤维层的定性和定量检测

OBJECTIVE: To study the characteristics of optical coherence tomography (OCT) of primary open angle glaucoma (POAG), the difference of retinal nerve fiber layer (RNFL) thickness between normal persons and patients with POAG and the correlation between RNLF and visual field index. METHODS: Eighty-three cases (149 eyes) with POAG and 83 normal persons (150 eyes) were tested by OCT with circular scans around the optic nerve head (diameter = 3.46 mm) to observe the features of OCT. Statistic analysis was taken to compare the difference of RNFL thickness in quadrants and means between normal and glaucomatous group, and the difference of the thickness among the stages in POAG. Linear correlation and regression analysis was used to show the correlation between RNFL thickness and visual field index of 115 eyes of glaucomatous patients. RESULTS: The RNFL thickness measured by OCT in normal subjects is the thickest in superior and inferior quadrants, less in thickness in temporal and the thinnest in nasal quadrant. The curve showed double peaks. The RNFL of glaucomatous patients showed local thinness or defect, diffuse thinness or combination of the above two types. The mean RNFL thickness of normal group was (90.1 +/- 10.8) microm, (140.4 +/- 10.5) microm, (85.2 +/- 14.0) microm, (140.4 +/- 9.7) microm and (114.2 +/- 6.0) microm, of glaucomatous group was (56.0 +/- 31.0) microm, (81.0 +/- 36.3) microm, (47.1 +/- 27.5) microm, (73.4 +/- 38.4) microm and (64.6 +/- 28.8) microm in temporal, superior, nasal, inferior quadrant and the whole area, respectively. There is significant difference of RNFL thickness between the normal and glaucomatous group (P < 0.000), and there are significant differences among the three stages (early, developing and late) of glaucomatous group (P < 0.000). There is a close negative relationship between RNFL thickness and visual field index (r = -0.796, P < 0.0001). The sensitivity and specificity of RNFL thickness measured by OCT were 93.3% and 92.0%, respectively. CONCLUSION: OCT can quantitatively measure the RNFL thickness and show the difference of RNFL between normal persons and glaucomatous patients. The RNFL thickness gradually decreases while visual field defect increases with the development of POAG.     

Quantification of retinal nerve fiber thickness. A comparison of laser scanning ophthalmoscopy, polarimetry and optical coherence tomography in healthy and glaucomatous eyes

Purpose. To evaluate the thickness of the retinal nerve fiber layer (RNFL) in healthy eyes and in eyes of patients with primary open angle glaucoma using the Heidelberg retina tomograph (HRT), the nerve fibre analyser (NFA) and the optical coherence tomograph (OCT). Methods. In this prospective cohort study, 40 normal eyes and 86 eyes of age-matched glaucoma patients were compared by confocal scanning laser tomography using the HRT, scanning laser polarimetry (NFA) and optical coherence tomography (OCT). The RNFL thickness was measured in the superior, inferior, nasal and temporal regions as well as the total circumference. Results. All three methods revealed a statistically significant difference between normal and glaucomatous eyes with respect to the mean RNFL thickness in the inferior and superior regions (p<0.001). The mean RNFL thickness in the superior region was 329 μm (HRT), 87 μm (NFA) and 94 μm (OCT) in healthy volunteers compared to 275 μm (HRT), 72 μm (NFA) and 82 μm (OCT) in the patient group. In the inferior region, it was 323 μm (HRT), 87 μm (NFA) and 93 μm (OCT) in healthy subjects versus 240 μm (HRT), 74 μm (NFA) and 83 μm (OCT) in glaucoma patients. Cut-off points to differentiate between normal and glaucomatous eyes could not be defined. There was no difference in the RNFL thickness of right and left eyes. Conclusions. In RNFL thickness measurements using HRT, NFA and OCT, glaucoma patients showed a significantly thinner RNFL in the superior and inferior areas compared to healthy volunteers. These results confirm the known histological and fundus photographic findings of RNFL thinning near the optic disc in glaucoma patients. Although RNFL thickness cannot be used to diagnose glaucoma in individual patients due to the high interindividual differences, the quantitative assessment of RNFL thickness may complement the diagnostic armamentarium as a sensitive parameter for diagnosing and monitoring glaucomas.     

Diagnostic capability of optical coherence tomography in evaluating the degree of glaucomatous retinal nerve fiber damage

PURPOSE: To evaluate the role and ability of optical coherence tomography (OCT) to detect differences in peripapillary retinal nerve fiber layer (RNFL) thickness between normal and glaucomatous eyes and also between different severities of glaucoma. METHOD: This cross-sectional observational study included 160 eyes of 160 healthy subjects and 134 eyes of 134 patients with primary open-angle glaucoma (POAG). Peripapillary RNFL thickness was measured on OCT using the fast RNFL thickness protocol. The RNFL thickness parameters used for evaluation included average RNFL thickness and inferior, superior, nasal, and temporal RNFL thickness. The glaucomatous eyes were subdivided into three subgroups on the basis of visual field defects and a fourth subgroup of eyes blinded by glaucoma. RNFL thickness parameters were compared among the normal eyes and the glaucoma subgroups. Correlation of global visual field indices with RNFL thickness parameters was also performed. RESULTS: The average RNFL in control subjects, early glaucoma, moderate glaucoma, severe glaucoma, and blind glaucoma were 102.30 +/- 10.34, 77.68 +/- 15.7, 66.07 +/- 15.5, 53.65 +/- 14.2, and 44.93 +/- 4.95 microm, respectively. There was a significant difference in all RNFL thickness parameters between normal and all glaucoma subgroups (P < 0.001). Average and inferior RNFL thicknesses showed the highest area under the receiver operating characteristic curve, with 0.905 and 0.862 for normal versus early glaucoma, 0.705 and 0.722 for early versus moderate glaucoma, 0.737 and 0.717 for moderate versus severe glaucoma, and 0.635 and 0.584 for severe versus blind glaucoma. Both mean deviation (MD) and corrected pattern standard deviation (CPSD) showed a significant correlation with all the RNFL thickness parameters in eyes with glaucoma (P < 0.001). CONCLUSIONS: RNFL thickness measured on OCT may serve as useful adjuncts in accurately and more objectively distinguishing normal from glaucomatous eyes, even in the early stages of glaucoma and may help to differentiate various severities of glaucoma. Average and inferior RNFL thicknesses are among the most efficient parameters for distinguishing such a differentiation. RNFL thicknesses in eyes blinded by glaucoma provide an estimate of the component of the RNFL thickness, which is not related to visual function.     

Retinal nerve fiber layer thickness in human eyes

· Background: A study was carried out to measure the thickness of the retinal nerve fiber layer (RNFL) at the optic disc border. · Methods: RNFL thickness at the optic disc border was histomorphometrically measured on histological sections of 22 human eyes with normal optic nerves and 21 human eyes with absolute secondary angle-closure glaucoma. For three eyes with normal optic nerves, serial sections through the whole optic disc area were available. · Results: In the eyes with normal optic nerves, the RNFL at the optic disc border showed a double hump configuration with the highest mean thickness in the inferior quadrant (mean ± S.D: 266±64 μm), followed by the superior quadrant (240±57 μm), the nasal quadrant (220±70 μm), and finally the temporal quadrant (170±58 μm). In the three globes with serial sections, RNFL was thickest at the inferior disc pole (397±58 μm), followed by the superior disc pole (313±38 μm), the nasal disc pole (165±19 μm), and finally the temporal disc pole (131±15 μm). In the eyes with absolute glaucoma, mean thickness of the remainder of the RNFL was 40±18 μm with no marked differences between the disc regions. · Conclusions: In normal eyes, the RNFL shows a double hump configuration with its thinnest part at the temporal disc pole, followed by the nasal disc pole and the superior disc pole. RNFL is thickest at the inferior disc pole. In glaucomatous optic neuropathy, the inner limiting membrane moves backward about 60–100 μm at the temporal disc border, and more than 200 μm at the inferior and superior disc poles. Received: 24 July 1998 Revised version received: 29 September 1998 Accepted: 22 October 1998     

青光眼视网膜神经纤维层厚度变化及其与视野缺损的相关性

目的　利用光学相干断层扫描（ｏｐｔｉｃａｌｃｏｈｅｒｅｎｃｅｔｏｍｏｇｒａｐｈｙ,ＯＣＴ）检测早期原发性开角型青光眼和可疑青光眼患者视网膜神经纤维层（ｒｅｔｉｎａｌｎｅｒｖｅｆｉｂｅｒｌａｙｅｒ,ＲＮＦＬ）厚度的变化,并分析其与视野缺损的相关性。方法　收集来我院就诊的可疑青光眼患者３５例（６３眼）为Ａ组,早期原发性开角型青光眼患者４１例（７２眼）为Ｂ组,对照组３４例（６６眼）为Ｃ组,采用ＯＣＴ仪和Ｈｕｍｐｈｒｅｙ７４０ｉ全自动视野计分别对３组受检者进行视盘周围ＲＮ-ＦＬ厚度和视野检测,比较３组患者的ＲＮＦＬ厚度,分析青光眼组ＲＮＦＬ厚度与视野缺损间的关系。结果　Ａ组的上方、下方象限及平均ＲＮＦＬ厚度与Ｃ组对应象限比较,差异均有统计学意义（均为Ｐ＜０．０５）;Ｂ组与Ｃ组比较平均及各象限ＲＮＦＬ厚度差异均有统计学意义（均为Ｐ＜０．０５）;Ａ组与Ｂ组比较上方、下方、鼻侧象限及平均ＲＮＦＬ厚度差异均有统计学意义（均为Ｐ＜０．０５）。三组受检者各象限及全周视野缺损两两比较,差异均有统计学意义（均为Ｐ＜０．０５）。Ｂ组平均及各象限ＲＮＦＬ厚度与视野缺损程度均呈负相关（均为Ｐ＜０．０５）。结论　青光眼患者ＲＮＦＬ厚度变薄,并且与视野缺损程度呈负相关。     

Morphometric analysis of human peripapillary retinal nerve fiber layer thickness

PURPOSE: The peripapillary retinal nerve fiber layer (RNFL) thickness pattern in the normal human eye has been well characterized using data obtained with scanning laser polarimetry and optical coherence tomography. The authors sought to characterize the normative peripapillary RNFL thickness and pattern using histologic sections obtained from healthy postmortem human eyes. METHODS: Seventeen unpaired normal postmortem eyes were recruited into this study. Each eye was sectioned using the "umbrella technique" to obtain four concentric peripapillary rings, each centered on the optic disc, with diameters of 3.0, 3.5, 4.0, and 4.5 mm. RNFL thickness data along each ring section was measured at 100 equidistant locations. Thickness data, for each ring diameter, across all eyes were averaged to arrive at normative thickness values for the peripapillary RNFL thickness in eyes processed using this technique. RESULTS: Average RNFL thicknesses (+/-SD) for the 3.5-mm diameter ring were as follows: overall, 60.3 +/- 19.5 microm; superior, 75.3 +/- 26.5 mum; inferior, 69.4 +/- 22.4 microm; nasal, 48.1 +/- 15 microm; temporal, 49.2 +/- 26.4 microm. Qualitatively, the RNFL thickness showed a double-hump pattern with relatively similar superior and inferior peaks and with temporal and nasal troughs. Progressively larger peripapillary rings showed progressively thinner RNFL thickness at all quadrants. In contrast, the relative thickness percentage for each quadrant remained unchanged among the four different diameter rings. CONCLUSIONS: Histologic data from a group of healthy postmortem eyes demonstrate the pattern of RNFL thickness in normal eyes. These data corroborate imaging findings of peripapillary RNFL thickness patterns obtained using commercially available RNFL imaging devices.     

Comparison of retinal nerve fibre layer measurements using optical coherence tomography versions 1 and 3 in eyes with band atrophy of the optic nerve and normal controls

AIMS: To compare retinal nerve fibre layer (RNFL) measurements were carried out with two different versions of an optical coherence tomography device in patients with band atrophy (BA) of the optic nerve and in normal controls. METHODS: The RNFL of 36 eyes (18 with BA and 18 normals) was measured using an earlier version of an optical coherence tomography device (OCT-1). The measurements were repeated using a later version of the same equipment (OCT-3), and the two sets of measurements were compared. RESULTS: Using OCT-1, the peripapillary RNFL thickness (mean+/-SD, in microm) in eyes with BA measured 80.42+/-6.94, 99.81+/-14.00, 61.69+/-13.02, 101.70+/-12.54, and 57.36+/-16.52 corresponding to the total RNFL average, superior, temporal, inferior, and nasal quadrants, respectively. Using OCT-3, the corresponding measurements were 63.11+/-6.76, 81.22+/-13.34, 39.50+/-8.27, 86.72+/-15.16, and 45.05+/-8.03. Each of these measurements was significantly smaller with OCT-3 than with OCT-1. In normal eyes, RNFL average and temporal quadrant OCT-3 values were significantly smaller than OCT-1 values, but there was no significant difference in measurements from the superior, inferior, and nasal quadrant. CONCLUSIONS: RNFL measurements were smaller with OCT-3 than with OCT-1 for almost all parameters in eyes with BA and in the global average and temporal quadrant measurements in normal eyes. Investigators should be aware of this fact when comparing old RNFL measurement with values obtained with later versions of the equipment.     

Detection of early glaucoma with optical coherence tomography (StratusOCT)

PURPOSE: To evaluate the performance of optical coherence tomography (StratusOCT) for discriminating eyes with early glaucoma from normal eyes. METHODS: Thirty eyes with established early glaucomatous visual field defects (EGVF group), 30 eyes with evidence of early glaucomatous optic neuropathy with normal standard achromatic perimetry [early glaucoma by disc (EGD)], and 33 age-matched normal eyes with good quality StratusOCT nerve fiber layer (NFL) images were enrolled. Average NFL thickness and NFL thickness at quadrants and sectors, areas under receiver operator characteristic curves, and sensitivities at 80% and 90% specificity were evaluated. RESULTS: The average (+/-SD) mean deviation in the EGVF group was -3.4 (+/-1.7) dB. Receiver operator characteristic curves showed areas under the curve (AUC) for NFL thickness in the superior quadrant (AUC=0.75+/-0.07) and in the inferior quadrant (AUC=0.94+/-0.03) to be the best StratusOCT parameters for discrimination of normal controls from EGD and EGVF eyes, respectively. The best parameter for detection of EGD eyes at 80% and 90% specificities was NFL thickness at superior quadrant (51% and 36% sensitivities, respectively). The best parameter for detection of EGVF eyes at 80% and 90% specificities was NFL thickness in the inferior quadrant (90% and 87% sensitivities, respectively). CONCLUSIONS: Optical coherence tomography (StratusOCT) showed good sensitivity and specificity in a group of glaucoma patients with early visual field loss. In patients with normal visual fields in whom the optic disc appeared glaucomatous to glaucoma specialists, half were confirmed to have StratusOCT findings consistent with damage from glaucoma.     

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。     

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.     

Comparison of retinal nerve fiber layer thickness and optic disk algorithms with optical coherence tomography to detect glaucoma

PURPOSE: To compare the performance of the retinal nerve fiber layer (RNFL) thickness and optic disk algorithms as determined by optical coherence tomography to detect glaucoma. DESIGN: Observational cross-sectional study. METHODS: setting: Academic tertiary-care center. study population: One eye from 42 control subjects and 65 patients with open-angle glaucoma with visual acuity of > or =20/40, and no other ocular pathologic condition. observation procedures: Two optical coherence tomography algorithms were used: "fast RNFL thickness" and "fast optic disk." main outcome measures: Area under the receiver operating characteristic curves and sensitivities at fixed specificities were used. Discriminating ability of the average RNFL thickness and RNFL thickness in clock-hour sectors and quadrants was compared with the parameters that were derived from the fast optic disk algorithm. Classification and regression trees were used to determine the best combination of parameters for the detection of glaucoma. RESULTS: The average visual field mean deviation (+/-SD) was 0.0 +/- 1.3 and -5.3 +/- 5.0 dB in the control and glaucoma groups, respectively. The RNFL thickness at the 7 o'clock sector, inferior quadrant, and the vertical C/D ratio had the highest area under the receiver operating characteristic curves (0.93 +/- 0.02, 0.92 +/- 0.03, and 0.90 +/- 0.03, respectively). At 90% specificity, the best sensitivities (+/-SE) from each algorithm were 86% +/- 3% for RNFL thickness at the 7 o'clock sector and 79% +/- 4% for horizontal integrated rim width (estimated rim area). The combination of inferior quadrant RNFL thickness and vertical C/D ratio achieved the best classification (misclassification rate, 6.2%). CONCLUSION: The fast optic disk algorithm performs as well as the fast RNFL thickness algorithm for discrimination of glaucoma from normal eyes. A combination of the two algorithms may provide enhanced diagnostic performance.     

Increasing sampling density improves reproducibility of optical coherence tomography measurements.

PURPOSE: Published series of peripapillary retinal nerve fiber layer (RNFL) measurements using optical coherence tomography (OCT) have sampled 100 evenly distributed points on a 360 degrees peripapillary circular scan. The goal of this study was to determine whether a four-fold increase in sampling density improves the reproducibility of OCT measurements. METHODS: Complete ophthalmic examinations, achromatic automated perimetry, and OCT imaging were performed in all patients. The OCT scanning consisted of three superior and inferior quadrantic scans (100 sampling points/quadrant) and three circular scans (25 points/quadrant). The RNFL thickness measurements and coefficient of variation (CV) were calculated for the superior and inferior quadrants for each sampling density technique. RESULTS: The study included 22 eyes of 22 patients (3 control subjects; 2 patients with ocular hypertension; and 17 patients with glaucoma). Quadrants with associated glaucomatous visual field loss on automated achromatic perimetry had thinner RNFLs than quadrants without functional defects for both the 25- and 100-points/quadrant scans. For quadrants associated with normal visual hemifields (n = 22), there was no difference between the 25- and 100-points/quadrant scans in mean RNFL thickness and CV. Among quadrants with visual field defects (n = 22), RNFL thickness measurements were thinner in the 25-points/quadrant scans than in the 100-points/quadrant scans. The CV for the 25-points/quadrant scans (25.9%) was significantly higher than that for the 100-points/quadrant scans (11.9%). CONCLUSION: Increasing the sampling density of OCT scans provides less variable representation of RNFL thickness. The optimal sampling density to achieve maximal reliability of OCT scans remains to be determined.     

Retinal nerve fiber layer thickness evaluation using optical coherence tomography in eyes with optic disc hemorrhage.

BACKGROUND AND OBJECTIVE: To examine the association between disc hemorrhage and retinal nerve fiber layer (RNFL) thickness. PATIENTS AND METHODS: RNFL thicknesses were measured using optical coherence tomography at the location of disc hemorrhage, at the superior or inferior symmetrical area of the same eyes, and at equivalent locations in contralateral eyes without disc hemorrhage. RNFL thicknesses were compared using the paired-sample t test. For recurrent hemorrhages, the correlation between the number of recurrences and RNFL thickness was examined using Kendall's tau-b method. RESULTS: Thirty-two disc hemorrhages were found in 32 eyes with normal tension or primary open-angle glaucoma. RNFL thicknesses in areas with disc hemorrhage were thinner than those in superior or inferior symmetrical locations in the same eyes (81.7 +/- 32.9 vs 100.7 +/- 34.5 microns, P = .005), but were not different from those in equivalent locations in contralateral eyes (92.8 +/- 31.7 microns, P = .092). Number of recurrent hemorrhages and RNFL thicknesses at sites of recurrent hemorrhages tended to show a negative correlation (correlation coefficient = -0.260, P = .079). CONCLUSIONS: Disc hemorrhage is associated with RNFL thinning measured by optical coherence tomography, and a negative correlation was found between recurrent hemorrhages and RNFL thickness.     

Multifocal VEP and OCT findings in patients with primary open angle glaucoma: A cross-sectional study

ABSTRACT: Bakground To evaluate objectively the anatomical and functional changes of optic nerve in eyes with primary open angle glaucoma (POAG) by the joint use of optical coherence tomography (OCT) and multifocal visual evoked potentials (mfVEP). METHODS: 29 eyes with open angle glaucoma and visual field defects, as well as 20 eyes of 10 age-matched control normal subjects were tested. All participants underwent a complete ophthalmological examination. Moreover, Humphrey visual field test, OCT examination and recording of mfVEP were performed. Amplitude and implicit time of mfVEP, as well as RNFL thickness were measured. Differences in density components of mfVEP and in RNFL thickness among POAG eyes and control eyes were examined using Student's t-test. RESULTS: In glaucomatous eyes the mean Retinal Response Density (RRD) was lower than normal in ring 1, 2 and 3 of mfVEP (p < 0.0001). Specifically the mean amplitude of mfVEP in POAG eyes was estimated at 34.2 +/- 17.6 nV/deg2, 6.9 +/- 4.8 nV/deg2 and 2.6 +/- 1.6 nV/deg2 in rings 1, 2 and 3 respectively. In contrast the mean implicit time was similar to control eyes. In addition, the mean RNFL thickness in POAG eyes was estimated at 76.8 +/- 26.6 mum in the superior area, 52.1 +/- 16.3 mum in the temporal area, 75.9 +/- 32.5 mum in the inferior area and 58.6 +/- 19.4 mum in the nasal area. There was a statistically significant difference in RNFL thickness in all peripapillary areas (p < 0.0001) between POAG eyes and controls, with superior and inferior area to present the highest decrease. CONCLUSIONS: Our study shows that, although Standard Automatic Perimetry is the gold standard to evaluate glaucomatous neuropathy, the joint use of mfVEP and OCT could be useful in better monitoring glaucoma progression.     

Reproducibility of nerve fiber layer thickness measurements by use of optical coherence tomography

OBJECTIVE: To evaluate the reproducibility of optical coherence tomograph (OCT) retinal nerve fiber layer (RNFL) measurements in normal and glaucomatous eyes by means of the commercially available OCT 2000 instrument (Humphrey Systems, Dublin, CA). DESIGN: Prospective instrument validation study. PARTICIPANTS: One eye each from 10 normal subjects and 10 glaucoma patients. METHODS: Twenty subjects underwent a total of eight scanning sessions during two independent visits. In each session, five circular scans centered on the optic nerve head were performed. The first two sessions were performed by two experienced technicians. Followed by a 30-minute break, a third and a fourth session was completed by the same technicians. This sequence was duplicated on a second visit. Intrasession, intersession, intervisit, and interoperator reproducibility of quadrant and global RNFL measurements were calculated by use of a components of variance model. MAIN OUTCOME MEASURES: RNFL thickness. RESULTS: The coefficient of variation for the mean RNFL thickness was significantly smaller (P = 0.02) in normal eyes (6.9%) than in glaucoma eyes (11.8%). The estimated root mean squared error based on the statistical model using three scans per patient was 5.8 and 8.0 micrometer for normal and glaucoma eyes, respectively. A components of variance model showed most of the variance (79%) to be due to differences between patients. Only a modest contribution to variability was found for session (1%), visit (5%), and operator (2%). CONCLUSION: With the commercially available OCT, our results indicate that the RNFL measurements are reproducible for both normal and glaucomatous eyes.     

Quantitative assessment of structural damage in eyes with localized visual field abnormalities

PURPOSE: To evaluate the pattern of structural damage in the macula and peripapillary retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT) and scanning laser polarimetry (SLP-VCC) in glaucomatous eyes with localized visual field defects. DESIGN: Prospective, cross-sectional analysis. METHODS: Complete examination, automated achromatic perimetry (AAP), Stratus OCT imaging (512 A-scans) of the peripapillary retina and macula, and SLP-VCC imaging of the peripapillary RNFL were performed. Thickness values in the retinal segments associated with the visual field defect (glaucomatous segments) were compared with corresponding segments across the horizontal raphe (nonglaucomatous segments) and age-matched normal controls. RESULTS: Forty eyes of 40 patients (20 normal, 20 glaucomatous) were enrolled (mean age, 71 +/- 10 years; range, 50 to 89). Mean RNFL thickness using SLP-VCC and OCT in the nonglaucomatous segments of glaucomatous eyes (54.0 +/- 9.7 microm, 64.7 +/- 19.0 microm) were significantly (P =.009, <0.0001) reduced compared with the thickness measurements in the corresponding segments of age-matched normal subjects (62.5 +/- 9.2 microm, 105.6 +/- 19.0 microm) respectively. No significant (P =.4) differences in the macular thickness measurements were observed between nonglaucomatous (239.0 +/- 19.4 microm) and normal segments (243.5 +/- 15.0 microm). Compared with age-matched controls, RNFL thickness in the nonglaucomatous segment was abnormal in 15 of 20 patients (75%) with SLP-VCC and in 18 of 20 patients (90%) with OCT. Macular thickness in the nonglaucomatous segment was abnormal in 11 of 20 patients (55%). CONCLUSIONS: Diffuse RNFL and retinal ganglion cell loss is present in eyes with localized visual field abnormalities. Detection of localized changes in macular thickness is limited by measurement overlap among normal and glaucomatous eyes.