Neural networks to identify multiple sclerosis with optical coherence tomography

Purpose:  To compare axonal loss in ganglion cells detected with spectral‐domain optical coherence tomography (OCT) in eyes of patients with multiple sclerosis (MS) versus healthy control subjects using an artificial neural network (ANN). To analyse the capability of the ANN technique to improve the detection of retinal nerve fibre layer (RNFL) damage in patients with multiple sclerosis. Methods:  Patients with multiple sclerosis (n = 106) and age‐matched healthy subjects (n = 115) were enrolled. The Spectralis OCT system was used to obtain the circumpapillary RNFL thickness in both eyes. The 768 RNFL thickness measurements provided by the Spectralis OCT were performed to obtain thickness measurements from 24 uniformly divided locations around the peripapillary RNFL. The performance of the ANN technique for identifying RNFL loss in patients with multiple sclerosis was evaluated. Receiver‐operating characteristic (ROC) curves were used to display the ability of the test to discriminate between MS and healthy eyes in our population. ROC curves obtained using ANN and parameters provided by OCT (mean and 6 sector thicknesses) were compared. Results:  The capability of the ANN technique to detect RNFL loss in patients with multiple sclerosis compared with healthy subjects was good. The area under the ROC curve was 0.945. Compared with the OCT‐provided parameters, the ANN had the largest area under the ROC curve. Conclusions:  Measurements of RNFL thickness obtained with Spectralis OCT have a good ability to differentiate between healthy and individuals with multiple sclerosis. Based on the area under the ROC curve, the ANN performed better than any single OCT parameter.     

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.     

糖尿病患者视网膜神经纤维层OCT测量的形态学观察

背景 传统的观点认为,糖尿病视网膜病变（DR）的主要病理机制是视网膜的微血管病变,但近年来发现糖尿病患者的视功能改变发生于DR的微血管病变发生之前,传统的观点无法解释糖尿病患者在出现可辨认的血管改变之前已有视功能改变的现象. 目的 应用频域光学相干断层扫描（OCT）观察无视网膜血管改变的糖尿病患者、非增生性糖尿病视网膜病变（NPDR）患者视网膜神经纤维层（RNFL）厚度的改变,分析糖尿病患者RNFL厚度与DR的关系. 方法 收集2012年10月至2013年9月于山西省眼科医院就诊且确诊的2型糖尿病患者56例60眼,按DR国际临床分型标准分为非糖尿病视网膜病变（NDR）组26例30眼和NPDR组（轻中度NPDR）30例30眼,同期纳入年龄和性别匹配的健康志愿者30人30眼作为对照.应用OCT对受试者行RNFL厚度测量,包括视盘周围及中心凹周围视网膜360°平均RNFL厚度及鼻上、颞上、颞侧、颞下、鼻下、鼻侧区域的RNFL厚度,比较各组患者RNFL厚度的变化. 结果 NDR组、NPDR组和正常对照组受试者视盘周围平均RNFL厚度分别为（97.46±8.65）、（100.69±16.35）和（109.22±8.69）μm,其中NDR组、NPDR组受试者视盘周围平均RNFL厚度值均低于正常对照组,差异均有统计学意义（P=0.001、0.006）;NDR组视盘周围各象限RNFL厚度均较正常对照组变薄,颞上、颞侧、颞下和鼻下象限RNFL厚度的差异均有统计学意义（P=0.001、0.001、0.001、0.010）;NPDR组视盘周围各象限RNFL厚度均较正常对照组变薄,其中颞上、鼻侧区域RNFL厚度的差异均有统计学意义（P=0.001、0.046）.NDR组、NPDR组和正常对照组平均黄斑区RNFL厚度分别为（33.47±3.39）、（36.81±3.21）、（38.18±2.16）μm,NDR组、NPDR组受试者黄斑区平均RNFL厚度值均低于正常对照组,其中NDR组与正常对照组比较差异有统计学意义（P=0.001）;NDR组黄斑区各区域RNFL厚度较正常     

OCT测量视网膜神经纤维层和黄斑厚度在青光眼早期诊断中的意义

目的应用光学相干断层成像术（optical coherence tomography，OCT）测量青光眼患者的视网膜神经纤维层（retinal nerve fiber layer，RNFL）厚度和黄斑厚度，比较两者在青光眼早期诊断中的作用。方法应用Stratus OCT测量62例（101眼）正常人和41例（64眼）青光眼患者的RNFL厚度和黄斑厚度，比较正常人和青光眼患者之间．正常人和早期青光眼患者之间上、下、鼻、颞四个象限与平均RNFL厚度、黄斑区内外环各象限厚度和总黄斑体积等参数有无统计学差异：用受试者工作特征曲线下面积（area under the receive operating characteristi ccurve，AROC）评价各个参数在青光眼早期诊断中的作用。结果青光眼患者各象限、平均RNFL厚度和各分区黄斑厚度、总黄斑体积均比正常人减少．差异有显著性（P=0．014—0．000），视乳头旁平均RNFL的AROC最大（0．961），其次为下方RNFL（0．928）和上方RNFL（0．924）。黄斑下方外环区AROC最大（0．876）。早期青光眼患者各象限、平均RNFL厚度和黄斑外环各分区、总黄斑体积较正常人减少，差异有显著性（P=0．021～0．000），而黄斑内环各区与正常人差异无显著性。视乳头旁平均RNFL的AROC最大（0．877），其次为上方RNFL（0．783）和下方RNFL（0．767）。黄斑下方外环区AROC最大（0．728）。结论测量RNFL厚度较测量黄斑厚度具有更强的青光眼早期诊断价值。黄斑厚度测量为青光眼的早期诊断提供了一种新的手段。     

A comparison of optical coherence tomography and retinal nerve fiber layer photography for detection of nerve fiber layer damage in glaucoma

PURPOSE: To compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurements with established methods for assessment of glaucomatous damage using RNFL photography and visual field testing. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-eight eyes of 58 healthy volunteer ocular hypertensive patients, glaucoma suspect patients, and glaucoma patients were included. METHODS: Optical coherence tomography 3.4-mm diameter circular scans were obtained within 3 months of RNFL photography and standard achromatic visual field testing. Three independent observers graded RNFL photographs using two standardized protocols. For each method, superior and inferior arcuate bundles were scored separately, and interobserver and intraobserver variation was measured. Standard achromatic visual field mean deviation in the superior and inferior hemifields was compared with RNFL damage as assessed by photography and OCT RNFL thickness measurements. MAIN OUTCOME MEASURES: Visual field mean deviation and severity of glaucomatous RNFL damage as assessed by photography. RESULTS: Optical coherence tomography RNFL thickness decreased with increasing RNFL damage as assessed by photography using both methods of photographic assessment. Standard achromatic perimetry mean deviation was significantly associated with OCT RNFL thickness (R(2) = 35%-43%) and RNFL photography severity score (R(2) = 18%-29%). CONCLUSIONS: These results suggest that the OCT shows promise for providing quantitative measures of RNFL thickness for diagnosing and monitoring glaucoma.     

Heidelberg retina tomography and optical coherence tomography in normal, ocular-hypertensive, and glaucomatous eyes.

PURPOSE: To evaluate optic disc and retinal nerve fiber layer (RNFL) appearance in normal, ocular-hypertensive, and glaucomatous eyes undergoing confocal scanning laser ophthalmoscopy and optical coherence tomography (OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS: Seventy-eight eyes of 78 consecutive normal (n = 17), ocular-hypertensive (n = 23), and glaucomatous subjects (n = 38) were enrolled. METHODS: Each patient underwent complete ophthalmic examination, achromatic automated perimetry, confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomography [HRT]), and OCT. Topographic HRT parameters (disc area, cup-disc ratio, rim area, rim volume, cup shape measure, mean RNFL thickness, and cross-sectional area) and mean OCT-generated RNFL thickness were evaluated in each group. MAIN OUTCOME MEASURES: OCT and HRT assessment of optic disc and RNFL anatomy. RESULTS: OCT RNFL thickness showed no difference between normal and ocular-hypertensive eyes (P = 0.15) but was significantly less in glaucomatous eyes (P < 0.001). HRT measurements of rim area, cup-disc ratio, cup shape measure, RNFL thickness, and RNFL cross-sectional area were significantly less in glaucomatous eyes (all P < 0.005) and were correlated with mean OCT RNFL thickness (all P < 0.02). RNFL thickness using OCT or HRT was highly correlated with visual field mean defect during achromatic perimetry (P < 0.0001). CONCLUSION: Both HRT and OCT can differentiate glaucomatous from nonglaucomatous eyes. RNFL thickness measurements using OCT correspond to disc topographic parameters using HRT.     

Association between risk factors and retinal nerve fiber layer loss in early stages of diabetic retinopathy

AIM:To investigate the changes of retinal nerve fiber layer(RNFL)among normal individuals,diabetic patients without diabetic retinopathy(NDR)and non-proliferative diabetic retinopathy(NPDR),and explore the possible risk factors of early diabetic retinopathy(DR).METHODS:In this cross-sectional study,107 participants were divided in three groups.Totally 31 normal individuals(control group),40 diabetic patients without DR(NDR group)and 36 patients with NPDR(NPDR group)were included.Optical coherence tomography(OCT)was used to detect RNFL thickness and other optic disc parameters among different groups.The potential association between RNFL loss and systemic risk factors were assessed for DR,including diabetes duration,body mass index(BMI),hemoglobin A1 c(Hb A1 c),serum lipids,and blood pressure.RESULTS:The average and each quadrant RNFL thickness were thinner in NPDR group compared to control group of the right(P=0.00,P=0.01,P=0.01,P=0.02,P=0.04)and left eyes(P=0.00,P=0.00,P=0.00,P=0.03,P=0.04).The average,superior and inferior RNFL thickness were thinner in NDR group compared to the NPDR group of the right(P=0.00,P=0.02,P=0.03)and left eyes(P=0.00,P=0.00,P=0.01).Diabetic duration was negatively correlated with the superior,inferior,and average RNFL thickness of the right(r=-0.385,P=0.001;r=-0.366,P=0.001;r=-0.503,P=0.000)and left eyes(r=-0.271,P=0.018;r=0.278,P=0.015;r=-0.260,P=0.023).Hb A1 c was negatively correlated with the superior,inferior,and average RNFL thickness of the right(r=-0.316 P=0.005;r=-0.414,P=0.000;r=-0.418,P=0.000)and left eyes(r=-0.367,P=0.001;r=-0.250,P=0.030;r=-0.393,P=0.000).Systolic pressure was negatively correlated with the inferior and average RNFL thickness of the right eye(r=-0.402,P=0.000;r=-0.371,P=0.001)and was negatively correlated with the superior and average RNFL thickness of the left eye(r=-0.264,P=0.021;r=-0.233,P=0.043).CONCLUSION:RNFL loss,especially in the superior and inferior quadrants,may be the earliest structural change of the retina in diabetic patients,and is also associated with diabetic duration,Hb A1 c,and systolic pressure.     

Retrobulbar administration of purified anti-nerve growth factor in developing rats induces structural and biochemical changes in the retina and cornea

AIM:To develop an experimental model of endogenous nerve growth factor(NGF)deprivation by retrobulbar administration of purified neutralizing anti-NGF antibodies in young Sprague-Dawley rats and provide further information on NGF expression in the retina and cornea.METHODS:Sixty old pathogen-free Sprague Dawley rats(p14,post-natal days)were treated with repeated retrobulbar injections of neutralizing anti-NGF(2μL,100μg/m L,every 3 d).After 2 wk(p28),retinal and corneal tissues were investigated for morphological,biochemical,and molecular expression of trkANGFR by using Western blotting or immunofluorescence.Rhodopsin as well as protein profile expression were also investigated.RESULTS:Chronic retrobulbar neutralizing anti-NGF antibodies changed the distribution of trkANGFR immunoreactivity at retinal level,while no changes were detected for global trkANGFR protein expression.By contrary,the treatment resulted in the increase of corneal trkANGFR expression.Retinal tissues showed a decreased rhodopsin expression as well as reduced number of both rhodopsin expressing and total retinal cells,as observed after single cell extraction.A decreased expression of ICAM-1,IL-17 and IL-13 as well as an increased expression of IL-21 typified retinal extracts.No significant changes were observed for corneal tissues.CONCLUSION:The reduced availability of endogenous NGF,as produced by chronic retrobulbar anti-NGF administration,produce a quick response from retinal tissues,with respect to corneal ones,suggesting the presence of early compensatory mechanisms to protect retinal networking.     

视网膜神经纤维层厚度与糖尿病视网膜病变程度的相关性研究

目的通过光学相干断层扫描(optical coherence tomography,OCT)仪观察具有不同视网膜病变程度的2型糖尿病患者及正常人视网膜神经纤维层(retinal nerve fiber layer,RNFL)厚度,探讨RNFL厚度与糖尿病视网膜病变(diabetic retinopathy,DR)的程度是否有相关性。方法正常对照组50人89眼,2型糖尿病患者75例130眼,按DR国际临床分型标准分为无糖尿病视网膜病变(non-diabetic retinopathy,NDR)组37例70眼、非增生性糖尿病视网膜病变(non-proliferative diabetic retinopathy,NPDR)组21例33眼、增生性糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)组17例27眼,所有患者均行眼科常规检查和OCT检查;OCT测量数据包括:视盘周围360°平均及上方、下方、鼻侧和颞侧平均RNFL厚度。结果正常对照组RNFL厚度视盘360°平均为(106.80±9.28)μm、上方(130.24±16.13)μm、下方(137.50±14.12)μm、鼻侧(75.02±8.90)μm、颞侧(84.20±12.39)μm;NDR组RNFL厚度360°平均为(104.20±7.12)μm、上方(120.46±20.40)μm、下方(137.63±11.18)μm、鼻侧(74.42±6.50)μm、颞侧(84.38±12.58)μm;NPDR组RNFL厚度360°平均为(86.67±4.22)μm、上方(105.97±7.22)μm、下方(114.97±5.29)μm、鼻侧(52.93±7.86)μm、颞侧(72.81±6.91)μm;PDR组RNFL厚度360°平均为(127.92±6.44)μm、上方(154.48±9.28)μm、下方(167.22±9.59)μm、鼻侧(83.33±9.83)μm、颞侧(106.63±10.40)μm。与正常对照组相比,NPDR、PDR组各方位RNFL厚度差异均有统计学意义(均为P<0.05),NPDR组变薄而PDR组变厚;NDR组与正常对照组比较,只有360°平均及上方有统计学意义(均为P<0.05);NDR、NPDR、PDR三组间两两比较,差异均有统计学意义(均为P<0.05)。结论糖尿病患者RNFL厚度的变化与DR的程度具有相关性,NDR及NPDR患者RNFL厚度变薄提示眼底开始出现神经节细胞凋亡的可能,当RNFL厚度由薄转为增厚则提示出病变的进行性加重,对临床早期诊断及治疗具有指导意义。     

Development of a novel reference plane for the Heidelberg retina tomograph with optical coherence tomography measurements

PURPOSE: To develop an ideal reference plane for the Heidelberg Retina Tomograph (HRT) with the assistance of optical coherence tomography (OCT) measurements of the mean retinal nerve fiber layer (RNFL) thickness. PATIENTS AND METHODS: The mean RNFL thickness was measured with OCT in eyes with early glaucoma (n = 50) and age-matched normal eyes (n = 40) at a circle as close as possible to the disc margin without touching it. Glaucomatous eyes were enrolled from chronic open-angle glaucoma patients with reproducible glaucomatous visual field defects with standard automated perimetry. One eye of each patient was randomly selected. A new reference plane was defined as located posteriorly from the mean height of the contour line by the amount of mean RNFL thickness measured with the OCT. Receiver-operating characteristic (ROC) curves were generated to compare the ability of parameters obtained with the conventional and the new reference plane to differentiate glaucomatous eyes from normal eyes. The same analysis was performed for early glaucomatous eyes with myopic refractive errors (n = 25). RESULTS: The areas under the ROC curves (AUCs) were greater for rim area, rim area/disc area, and rim volume with the new reference plane compared with those with the conventional reference plane, but they were not significantly different. When the same analysis was performed for myopic glaucomatous eyes, the AUCs for rim area, rim area/disc area, and rim volume with the new reference plane were greater than those with the conventional reference plane ( = 0.002, 0.010, and 0.034, respectively). CONCLUSION: A novel reference plane for the HRT defined by OCT measurements may improve the ability of the HRT to detect early glaucoma, especially in eyes with tilted discs.     

Comparability of retinal nerve fiber layer thickness measurements of optical coherence tomography instruments

PURPOSE: To compare retinal nerve fiber layer (RNFL) measurements between two ocular coherence tomography (OCT) instruments (OCT 2000 and Stratus OCT; Carl Zeiss Meditec, Dublin, CA) and compare their diagnostic precision. METHODS: One hundred thirty-nine consecutive subjects were imaged (3 x 3.4-mm diameter circular scans) on the same day with each instrument. Thirty-five patients were excluded due to poor-quality images. RNFL thicknesses measured by the two instruments were compared, and receiver operating characteristic (ROC) curves were used to determine diagnostic precision. RESULTS: A randomly selected eye of each of 104 participants (28 with open-angle glaucoma, 40 with suspected glaucoma, and 36 healthy subjects) was analyzed. RNFL thickness measurements generally were thicker with OCT 2000 than with Stratus OCT. The difference in global RNFL thickness between instruments was within 20 microm in 66 (65%) of subjects and within 10 microm (the instrument's limit of resolution) in 25 (25%) subjects. Application of a correction factor to OCT 2000 measurements predicted Stratus OCT RNFL thickness within 10 microm of the observed measurement in 75% of the eyes. For both instruments, highest ROC curve areas (better discrimination between glaucomatous and normal eyes) were found in the inferior sector. Discrimination using global RNFL thickness was better with Stratus OCT than OCT 2000 (P = 0.043). CONCLUSIONS: RNFL thickness measurements measured by OCT 2000 can be approximated to measurements made by Stratus OCT using correction factors calculated by this study. However, there remains considerable variability that exceeds the limits of resolution afforded by the instruments themselves. Therefore comparisons between instruments using these approximations should be interpreted with caution.     

Blue-on-yellow perimetry and optical coherence tomography in patients with preperimetric glaucoma

Purpose: To investigate the diagnostic ability of blue‐on‐yellow perimetry (B/YP) and Stratus optical coherence tomography (OCT) in discriminating preperimetric glaucoma from normal eyes. Methods: A total 40 eyes of 40 normal subjects, 38 eyes of 38 preperimetric glaucoma patients (normal standard automated perimetry [SAP] and retinal nerve fibre layer [RNFL] defects or localized optic disc notching and thinning) were enrolled in the study. All the patients underwent SAP and B/YP tests, and OCT measurements. The correlation between B/YP indices and OCT parameters in the eyes with preperimetric glaucoma was analysed. Receiver operating characteristic (ROC) curve area was calculated to discriminate preperimetric glaucoma from normal eyes. Results: In preperimetric glaucoma, 42% eyes (16/38) had B/YP visual field loss, and 68% eyes (26/38) had RNFL defects with OCT measurements. A mild significant correlation was found between B/YP pattern standard deviation (PSD) and average RNFL thickness (Avg.Thi) (R² = 0.112, P = 0.012), superior maximum (Smax) (R² = 0.140, P = 0.005) and maximum‐minimum (Max‐Min) (R² = 0.074, P = 0.042) in the preperimetric glaucoma group. The areas under the ROC curve for B/YP PSD and B/YP mean deviation were 0.721 and 0.665, respectively, and the three OCT parameters with the widest areas under the ROC curve were Avg.Thi (0.719), inferior average (Iavg) (0.718) and nasal average (Navg) (0.706). The highest sensitivity of the individual B/YP indices and OCT parameters for detection of preperimetric glaucoma was B/YP mean deviation (32%) and Smax/Navg (40%) at 90% specificity; the highest sensitivity of the individual B/YP indices and OCT parameters was B/YP PSD (49%) and Iavg (56%) at 80% specificity. Conclusion: The sensitivity of B/YP indices and Stratus OCT RNFL thickness parameters is low for detecting preperimetric glaucoma, suggesting that BYP and OCT as utilized in this study have limited utility in the detection of preperimetric glaucoma.     

Retinal nerve fiber layer analysis: relationship between optical coherence tomography and red-free photography.

PURPOSE: Comparison of retinal nerve fiber layer (RNFL) thickness measurements using optical coherence tomography (OCT) to the clinical standard red-free photography (evaluated semiquantitatively), in relation to functional visual field damage in primary open-angle glaucoma (POAG) patients, ocular hypertensives, and POAG suspects. METHODS: Concurrent, cross-sectional study. In four age-matched groups (42 patients with early to moderate POAG, 34 ocular hypertensives, 22 POAG suspects, and 25 normal controls), RNFL was assessed with OCT, standardized red-free photographic scoring method and standard achromatic perimetry. RESULTS: OCT RNFL thickness decreases with increased RNFL damage (detected with red-free photography). The global average OCT RNFL thickness correlated significantly with the photographic total RNFL score (r = .650, P = .0001). Both OCT and photographic scoring system were able to find significantly thinner RNFL in the glaucoma group as compared with normals (P = .0001 for both), ocular hypertensives (P = .0001 for both), and suspects (P = .0001 for both). However, neither OCT nor photography could significantly differentiate between ocular hypertensives, suspects, and normals. Both OCT and photography were significantly correlated with VF loss. For the percentage of VF points depressed <5%, the correlation was highest for OCT (r = -0.615 for OCT and r = -0.476 for photography). OCT had a higher diagnostic accuracy than photography (86% and 77%, respectively). CONCLUSION: For RNFL thickness measurements, the presence of high correlations between OCT, photographic scores, and functional visual field loss suggest the validity of OCT measurements. The higher diagnostic accuracy of OCT RNFL measurements suggests its potential advantage for detection of early cases of glaucoma.     

Attenuation of the retinal nerve fibre layer and reduced retinal function assessed by optical coherence tomography and full‐field electroretinography in patients exposed to vigabatrin medication

Purpose: To investigate the clinical value of assessment of peripapillary retinal nerve fibre layer (RNFL) thickness with OCT in addition to the evaluation of retinal function measured by full‐field electroretinography (ff‐ERG) in patients with suspected vigabatrin (VGB)‐attributed visual field defects. Methods: Visual fields from adult patients in our clinical follow‐up program for VGB medication were analysed. Twelve patients with suspected VGB‐attributed visual field defects were selected for the study. They were re‐examined with computerized kinetic perimetry, ff‐ERG and OCT (2D circle scan). Results: Constricted visual fields were found in all patients. Comparative analysis of ff‐ERG parameters showed reduced b‐wave amplitudes for the isolated and the combined rod and cone responses (p < 0.0001). The a‐wave, reflecting photoreceptor activity, was reduced (p = 0.001), as well as the summed amplitude of oscillatory potentials (p = 0.029), corresponding to inner retinal function. OCT measurements demonstrated attenuation of the RNFL in nine of 12 patients, most frequently superiorly and/or inferiorly. No temporal attenuation was found. Significant positive correlations were found between the total averaged RNFL thickness, superior and inferior RNFL thickness and reduced ff‐ERG parameters. Positive correlations were also found between RNFL thickness and isopter areas. Conclusion: OCT measurements can detect attenuation of the RNFL in patients exposed to VGB medication. RNFL thickness correlates with reduced ff‐ERG parameters and isopter areas of constricted visual fields, indicating that VGB is retino‐toxic on several levels, from photoreceptors to ganglion cells. The study also supports previous studies, suggesting that OCT measurement of the RNFL thickness may be of clinical value in monitoring patients on vigabatrin therapy.     

Optical coherence tomography, frequency-doubling technology, and colour Doppler imaging in ocular hypertension

PURPOSE: To study in ocular hypertension (OH) the retinal nerve fibre layer (RNFL) with optical coherence tomography (OCT) and the neuronal function with frequency-doubling technology (FDT) to assess which of the two methods was more sensitive in detecting early glaucomatous damage. Furthermore, a colour Doppler imaging (CDI) of the optic nerve was carried out to highlight any correlation with RNFL thickness and FDT abnormality. MATERIALS AND METHODS: We enrolled 28 ocular hypertensive patients who underwent OCT of the RNFL and FDT. Moreover, we performed a CDI of the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs). RESULTS: The patients with OH following OCT revealed a significant thinning in the RNFL as compared to the control group only in the inferior quadrant: 122.250+/-14.091 vs131.750+/-10.729 mum (P<0.045). As regards FDT, there was a significant difference between the two groups only for pattern standard deviation (PSD): 3.873+/-1.488 vs1.938+/-0.704 dB (P<0.044). In OH and in the control group, CDI resistance index (RI) in the OA was 0.768+/-0.012 vs0.745+/-0.019 (P<0.022), in the CRA was 0.66+/-0.012 vs0.645+/-0.019 (P<0.032), and in PCAs was 0.673+/-0.039 vs0.622+/-0.012 (P<0.037). The OCT had a sensitivity of 83% but only in the inferior RNFL quadrant. The FDT-PSD revealed a sensitivity of 85%. CONCLUSIONS: Both FDT and OCT detect early glaucomatous damage with a slightly superior sensitivity of FDT vsOCT. The CDI measurements suggest that circulatory abnormalities may have a role in the development of OCT and FDT damage.     

Evaluation of scanning resolution on retinal nerve fiber layer measurement using optical coherence tomography in normal and glaucomatous eyes

PURPOSE: To evaluate the effect of varying the scanning resolution of optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) measurement on diagnostic sensitivity and functional correlation in glaucoma. PATIENTS AND METHODS: 314 eyes from 182 subjects including 107 normal eyes, 83 glaucoma suspect eyes, and 124 glaucoma eyes were included in this cross-sectional study. Standard automated perimetry and OCT measurement of RNFL thickness were performed. Each individual underwent two scanning protocols: (1) fast RNFL thickness (3.4) scan (with resolution of 256 scan points) and (2) RNFL thickness (3.4) scan (with resolution of 512 scan points). RNFL thickness was compared among the groups. Diagnostic sensitivity was evaluated with Receiver Operating Characteristic (ROC) Curve. Relationship between RNFL thickness and visual field mean deviation was examined using linear regression analysis. RESULTS: Measured RNFL thickness using fast RNFL thickness (3.4) scan was significantly higher compared with RNFL thickness (3.4) scan in average, superior, nasal and inferior RNFL in all diagnostic groups. Comparing normal and glaucoma groups, RNFL thickness (3.4) scan produced the largest area under the ROC curve (0.912) based on average RNFL thickness. A stronger correlation between average RNFL and visual field mean deviation was found in RNFL thickness (3.4) scan (R = 0.75, R = 0.56). CONCLUSIONS: Higher resolution RNFL scan provides better diagnostic sensitivity in glaucoma detection and a stronger correlation with visual function.     

Comparison of the Diagnostic Ability of Retinal Nerve Fiber Layer Thickness Measured using Time Domain and Spectral Domain Optical Coherence Tomography in Primary Open Angle Glaucoma

 Purpose: To evaluate and compare the diagnostic ability of retinal nerve fiber layer (RNFL) thickness measurements using time domain (Stratus) and spectral domain (Cirrus HD) optical coherence tomography (OCT) in preperimetric and early primary open angle glaucoma (POAG). Methods: A total 62 eyes of 62 normal subjects, 47 eyes of 47 early perimetric damage POAG patients and 30 eyes of 30 preperimetric glaucoma patients were chosen in the study. All the subjects underwent peripapillary RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT on the same day by a single trained operator. The RNFL thickness measured by Stratus OCT and Cirrus HD-OCT was statistically compared using paired t-tests. The relationship between RNFL thickness measured by two OCT instruments was evaluated using Pearson’s correlation coefficient. Areas under the receiver operating characteristic curves (AROC) were calculated and compared. Results: RNFL thickness measured using Stratus OCT was generally thicker than that using Cirrus HD-OCT(P＜0.05). A highly significant correlation between the two OCT instruments measurements was found in four quadrants and average RNFL thickness measurements (P＜0.001). The average RNFL thickness of Cirrus HD-OCT had significantly (P = 0.006) higher diagnostic ability (AROC = 0.951) than that of Stratus OCT (AROC = 0.881) in preperimetric glaucoma. There were no significant differences between the AROCs for other RNFL thickness parameters from Cirrus HD-OCT and Stratus OCT in preperimetric and early glaucoma (P＞0.05). Conclusion: Significant differences and an excellent correlation were noted in terms of RNFL thickness measurements using Stratus OCT and Cirrus HD-OCT. Cirrus HD-OCT presented higher diagnostic ability for preperimetric glaucoma.     

Retinal nerve fiber layer measurement by optical coherence tomography in glaucoma suspects with short-wavelength perimetry abnormalities

PURPOSE: To compare retinal nerve fiber layer (RNFL) measurements in normal and glaucoma subjects with short-wavelength automatic perimetry (SWAP) abnormalities and in chronic primary open-angle glaucoma (CPOAG) patients using optical coherence tomography (OCT). METHODS: Forty-eight eyes of normal subjects, 34 eyes of glaucoma suspects with SWAP abnormalities, and 38 eyes of early CPOAG subjects were recruited. All normal and glaucoma suspects had normal conventional automated perimetry visual field results. All participants underwent full clinical ophthalmologic evaluation followed by OCT RNFL measurements. RESULTS: Compared with normal controls, OCT RNFL thickness was significantly lower in glaucoma suspects with abnormal SWAP (inferotemporal and superotemporal thickness values) and CPOAG patients (average, superior, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01). Some parameters were found to be significantly lower in CPOAG patients than the glaucoma suspects with abnormal SWAP (average, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01). CONCLUSIONS: OCT RNFL measurements appear to correlate well with SWAP abnormalities in glaucoma, and may detect glaucomatous damage earlier than standard conventional automated perimetry. This study suggests that OCT may recognize the earliest evidence of structure alterations in CPOAG.     

Retinal nerve fiber loss in high- and normal-tension glaucoma by optical coherence tomography.

PURPOSE: To compare the pattern of retinal nerve fiber layer (RNFL) damages in high-tension and normal-tension primary chronic open-angle glaucoma using optical coherence tomography (OCT). METHODS: Age- and refractive error-matched patients with normal-tension glaucoma (NTG) (n = 38) and high-tension glaucoma (HTG) (n = 48) and normal subjects (n = 48) were recruited. All subjects underwent complete eye examinations and OCT RNFL assessments. RESULTS: No statistically significant difference was found between eyes with HTG and NTG for any OCT RNFL thickness parameters (p > 0.05). Inferotemporal thickness values were significantly lower than the superotemporal thickness values in both glaucoma groups (p < 0.001), but no difference was observed in the normal group. Compared with the results from normal subjects, several OCT parameters, including average, superior, inferior, inferotemporal, and superotemporal values, were significantly lower in patients with HTG and NTG (p < 0.01). CONCLUSIONS: A mixture of diffuse RNFL damage (superotemporal and inferotemporal regions) and local damage in inferotemporal region was observed in patients with HTG and NTG, suggesting that HTG and NTG may undergo same pathological process.     

Application of shape-based analysis methods to OCT retinal nerve fiber layer data in glaucoma

PURPOSE: (1) To evaluate the performance of shape-based analysis [wavelet-Fourier analysis (WFA) and fast Fourier analysis (FFA)] applied to retinal nerve fiber layer (RNFL) thickness values obtained from the optical coherence tomograph (OCT) to discriminate healthy and glaucomatous eyes. (2) To compare the performance of the shape-based metrics to that of the standard OCT output measures (Inferior Average and Average Thickness). METHODS: RNFL values were obtained from 152 eyes of 152 individuals (83 healthy and 69 "mild"-stage perimetric glaucoma). WFA and FFA were performed on the RNFL values and linear discriminant functions for both were obtained using Fisher linear discriminant analysis. Performance was evaluated by calculating sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (ROC area). RESULTS: The ROC area of the shape-based methods [0.94 (WFA) and 0.88 (FFA)] was greater than that of OCT metrics [0.81 (Inferior Average) and 0.74 (Average Thickness)]. Specifically, WFAs performance was significantly better than both the FFA (P=0.009) and the Inferior Average (P=0.001). Inferior average performed significantly better than Average Thickness (P=0.006). CONCLUSIONS: The ability to differentiate glaucomatous from healthy eyes using stratus OCT measurements is improved by using these analysis methods that emphasize the shape of the RNFL thickness pattern.