Variability of Heidelberg Retina Tomograph parameters during exercise

Purpose: The purpose of this study was to determine whether exercise affects the stereometric parameters representing optic nerve head (ONH) topography. Methods: ONH topography, intraocular pressure (IOP) and blood pressure of 30 healthy volunteers were monitored before, during and after dynamic exercise raising systolic blood pressure by a minimum of 30 mmHg. Change in the stereometric ONH parameters was calculated. Results: IOP decreased and blood pressure increased during exercise, resulting in an increase in mean ocular perfusion pressure. Exercise was associated with an increase in variance in 17 of the 18 stereometric ONH parameters. The increase in variance was statistically significant in eight parameters, including rim area, cup/disc area ratio and cup shape measure. There was no statistically significant change in image quality. The absolute change from baseline in rim area, cup area, cup/disc area ratio, rim/disc area ratio and rim volume showed a statistically significant (p < 0.05) correlation with change in mean ocular perfusion pressure. Conclusions: Exercise increases variability in stereometric ONH parameters. To avoid increased variance in the stereometric parameters, ONH imaging should be performed after allowing sufficient time to rest.     

用Heidelberg视网膜断层扫描仪对正常人、大杯和青光眼视乳头形态结构的研究

目的：探讨正常人、大杯和原发性开角型青光眼（ｐｒｉｎａｒｙ ｏｐｅｎ ａｎｇｌｅ ｇｌａｕｃｏｍａ,ＰＯＡＧ）患者之间视乳头结构参数之间的差异。方法：用Ｈｅｉｄｅｌｂｅｒｇ视网膜断层扫描仪（Ｈｅｉｄｅｌｂｅｒｇ Ｒｅｔｉｎａ Ｔｏｍｏｇｒａｐｈ,ＨＲＴ）对正常人（２２例４４眼）、大杯（１７例３４眼）和ＰＯＡＧ患者（１９例３７眼）进行视乳头断层扫描,获得视乳头平均地形图图像和视乳头结构诸参数。结果：     

Agreement in identification of glaucomatous progression between the optic disc photography and Heidelberg retina tomography in young glaucomatous patients

AIM:To evaluate concordance between the clinical assessment of glaucomatous progression of the optic disc photography and progression identified by Heidelberg Retina Tomograph (HRT) in patients with suspected primary juvenile open angle glaucoma (JOAG).METHODS:Optic disc photographs and corresponding HRT Ⅱ series were reviewed. Optic disc changes between first and final photographs were noted as well as progression identified by HRT topographic change analysis (TCA) and rim area regression line (RARL) Agreement between progression indentified by photography and HRT methods was assessed. Progression, determined from optic disc photographs by consensus assessment was used as the reference standard.RESULTS: A total of 31 patients (59 eyes) with suspected JOAG were studied. Agreement for progression/no progression between TCA and photography was obtained in 4 progressing eyes and 38 stable eyes (71.19%, k=0.11). Agreement for progression/no progression between RARL and photography was detected in 5 progressing eyes and in 34 stable eyes (66.10%, k=0.15). The number of HRT per patient was statistically higher in the progressing group (P=0.034).CONCLUSION:Agreement for detection of longitudinal changes between photography and HRT analysis was poor. One way to improve the chance of discovery of the progression could be increasing the number of HRT examinations.     

用Heidelberg视网膜断层扫描仪对正常眼压性青光眼与正常人视盘形态结构的对比研究

目的 比较正常人(本文所指正常人指非青光眼者)和正常眼压性青光眼(Normal Tension Glaucoma，NTG)视盘形态结构参数之间的差异，以指导正常眼压青光眼的早期诊断。方法 用Heidelberg视网膜断层扫描仪(Heidelberg Retina Tomograph Ⅱ，HRTⅡ)对正常人40例(80眼)及NTG30例(60眼)的视乳头进行断层扫描，获得视乳头平均地形图像和视乳头结构诸参数。结果 正常人与NTG视乳头结构各参数中视盘面积、视杯面积、杯盘比、盘沿面积、视杯容积、平均视杯深度、最大视杯深度、平均视神经纤维层厚度及视神经纤维层横截面积存在明显差异。结论 HRT能在活体对视乳头结构进行准确分析，视盘面积可能是青光眼的一个易感因素，对NTG早期诊断具有帮助。     

Comparison of optic nerve head parameters using Heidelberg Retina Tomograph 3 and spectral-domain optical coherence tomography

Background: To assess the agreement between the Heidelberg Retina Tomograph and Cirrus spectral‐domain optical coherence tomography (Cirrus HD‐OCT [Carl Zeiss Meditec, Dublin, CA, USA]) when measuring optic disc parameters. Design: Prospective, cross‐sectional study. Participants: A total of 96 glaucoma patients and 21 normal subjects were analysed. Methods: Optic nerve head measurements, including disc area, rim area, cup‐to‐disc ratio and cup volume were obtained using both the Cirrus HD‐OCT and Heidelberg Retina Tomograph 3 (Heidelberg Engineering GmbH, Heidelberg, Germany). Main Outcome Measurements: Bland–Altman plots were used to evaluate the agreement between each of the optic disc parameters. Results: Although Cirrus HD‐OCT values were smaller than Heidelberg Retina Tomograph 3 values for the disc and rim areas, overall the Cirrus HD‐OCT and Heidelberg Retina Tomograph 3 measurements were highly correlated (r = 0.657 to 0.821). As compared with Heidelberg Retina Tomograph 3, disc and rim areas tended to be minimized by Cirrus HD‐OCT, especially when there were large disc and rim areas, although there was no relationship between the discrepancy and the level of measurement of the cup‐to‐disc ratio. The optical coherence tomography overestimated the Heidelberg Retina Tomograph‐determined cup volume, especially when there were large cup volumes. Conclusions: Bland–Altman analyses revealed that with the exception of the cup‐to‐disc ratio, there was poor agreement between the Cirrus HD‐OCT and Heidelberg Retina Tomograph 3 morphometric measurements. In addition, with the exception of the cup‐to‐disc ratio, the optic nerve head measurements could not be directly compared between the Cirrus HD‐OCT and Heidelberg Retina Tomograph 3.     

Study on Stereometric Parameters of Optic Nerve Head of Normal,Big—cup

Purpose: To investigate the difference of stereometric parameters of optic nerve head between the normal subjects and patients with big-cupped disk and primary open angle glaucoma (POAG).Methods: Twenty-two cases (44 eyes) of normal subjects, 17 cases (34 eyes) of patients with big-cupped disk and 19 cases (37 eyes) of patients with POAG underwent Heidelberg Retina Tomograph (HRT) examination to get topography images and stereometric parameters of optic nerve head.Results: The stereometric parameters of optic nerve head of the normal, patients with big-cupped disk and POAG were 1) disk area (mm2): 1. 995± 0. 501, 2. 407±0. 661 and 2. 248±0.498; 2) cup area (mm2): 0.573±0.264, 1. 095±0. 673 and 1. 340±0. 516; 3) cup/disk ratio: 0. 25±0. 095, 0. 428±0. 176 and 0. 589±0.195; 4) rim area (mm2): 1.461±0.328, 1.312±0.418 and 0. 905± 0.409; 5)cup volume (mm3): 0. 108±0. 073, 0. 347±0. 346 and 0. 550 ±0. 394; 6) rim volume (mm3): 0. 421±0. 111, 0. 378±0. 225 and 0. 224±0. 189; 7) mean cup dept     

Assessment of optic disc parameters among healthy adult Malays by Heidelberg Retinal Tomograph II

Background: This study aims to assess the optic disc characteristics in healthy adult Malays and to correlate them with age, gender and refractive errors. Design: Cross‐sectional study. Participants: A total of 200 voluntary participants (106 women and 94 men) among Malay students aged 20 to 37 years at Health Campus, Universiti Sains Malaysia. Methods: The relationship between Heidelberg Retinal Tomograph parameters with age, gender and refractive error were analysed with correlation tests and multiple linear regression analyses. Main Outcome Measures: Twelve parameters, that is, disc area, rim area, cup area, cup to disc area, cup volume, rim volume, height variation contour, cup shape measure, mean cup depth, maximum cup depth, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross‐sectional area. Results: Disc area, rim area and cup : disc area ratio averaged 2.24 ± 0.52 (mean ± standard deviation), 1.64 ± 0.32 and 0.25 ± 0.12 mm², respectively. Five parameters (disc area, cup area, cup volume, cup : disc area ratio and mean retinal nerve fibre layer thickness) showed statistically significant difference between men and women. Age was negatively and significantly correlated with rim area with coefficient r = ?0.21, P = 0.003. All optic disc parameters were significantly correlated (P < 0.05) with disc area, except cup shape measure. Conclusions: One or more of optic disc parameters were affected significantly by age, gender and disc area in healthy adult Malays' eyes. These factors need to be considered during the evaluation of optic disc.     

Test-retest variation in macular thickness measurements with the Heidelberg Retina Tomograph

Purpose: The aim was to evaluate the test-retest variation of macular thickness measurements using the Heidelberg Retina Tomograph (HRT3) Retina Module and compare it with the Stratus optical coherence tomography (OCT). As no normative data has been published for the HRT Retina Module, a secondary purpose was to obtain reference values for this technique. Methods: Thirty healthy subjects and nine patients with macular oedema were examined. The healthy subjects underwent five examinations by two experienced examiners at two different occasions. The patients with maculopathy were examined twice by one examiner on one occasion. All measurements were made with both the HRT3 and the Stratus OCT and the macular thickness measurements were used for calculations of the test-retest variation. Results: In healthy subjects the coefficient of variation (CV) ranged from 4.5 to 8.8 per cent with the HRT3 and from 0.6 to 1.5 per cent with the Stratus OCT. In the nine patients with macular oedema, the HRT CV ranged from 7.9 to16.6 per cent and for OCT from 1.1 to 2.5 per cent. The intra-class correlation in the central area for intra-observer/intra-visit in healthy subjects was 0.78 with the HRT3 and 0.93 with the Stratus OCT. Corresponding values for the patients with macular oedema were 0.64 with the HRT3 and 1.0 with the Stratus OCT. Mean macular thickness was significantly larger in all areas measured with the HRT3 compared with the Stratus OCT. No significant correlations were found between the thickness values from the different instruments. Conclusion: In this study, macular thickness was measured with two different techniques. The HRT3 showed lower repeatability and reproducibility as well as a higher CV compared with the Stratus OCT in both healthy subjects and patients with macular oedema. This difference might be of clinical relevance, even though the nine patients with maculopathy in the current study showed abnormal results with both methods.     

Clinical and experimental findings in Acanthamoeba keratitis with Heidelberg Retina Tomograph III-RCM.

PURPOSE: To observe Acanthamoeba cysts and trophozoites in the corneal tissue of patients and rabbits with Acanthamoeba keratitis (AK), using the Heidelberg Retina Tomograph III Rostock-cornea-module (HRTIII-RCM). METHODS: Eight eyes of seven patients with clinical and laboratory diagnosis of AK, presenting to the Beijing Institute of Ophthalmology between July and December 2006, were included in this study. The laboratory diagnosis in all cases was established by a cytological analysis and culture of the corneal scraping. The scanning with HRTIII-RCM was performed on all the patients. Acanthamoeba cysts and trophozoites in the corneas of three rabbits were observed with the HRTIII-RCM after a suspension of trophozoites was injected into the corneal stromal layer of the rabbits. RESULTS: Acanthamoeba cysts or trophozoites were observed with the HRTIII-RCM in the corneas of all the patients. The size and shape of Acanthamoeba in the tissue of the rabbit corneas was consistent with that in the patients' eyes. The Acanthamoeba cyst presented a round high-contrast particle, 15-20 microm in diameter, with a double wall. In contrast, the trophozoite presented an irregular high-contrast particle, without an apparent wall, 25-40 microm in diameter and with a round conspicuous nucleus. CONCLUSIONS: HRTIII-RCM is a useful non-invasive clinical technique to help to diagnose and monitor the response of AK to therapy.     

Reproducibility of volumetric macular measurements in diabetic patients with the Heidelberg Retina Tomograph

Aims: To quantify diabetic macular edema by confocal scanning laser ophthalmoscopy and assess its usefulness by determining the reproducibility of topographic measurements at the macula. Methods: The volumes above reference plane bound by a 2 mm diameter circle centred on the fovea were measured by two observers. The reference plane was adjusted to the lowest point of the height variation of the contour line. The reproducibility of this technique was assessed in 20 eyes of 20 diabetic patients of which 8 eyes had macular edema. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times. Results: For all diabetic eyes, the intra scan coefficients of variability measured 14.71% to 21.21%, the inter scan coefficient of variability was 30.46%. The average standard deviations were 0.053 mm³ for one examination per scan, 0.047 mm³ for two examinations per scan and 0.044 mm³ for three examinations per scan. Linear regression demonstrated an increase in standard deviation with greater volumetric measurements (p < 0.001). We found good correlation (r = 0.959, p < 0.001) and strong agreement between the two observer's findings for all 20 eyes. For the 8 eyes with macular edema, the coefficients of variability were similar to those calculated for all 20 eyes. The average SD for one examination per scan were 0.078 mm³, 0.069 mm³ for two examinations per scan and 0.062 mm³for three examinations per scan. We found good correlation (r = 0.945, p < 0.001) and strong agreement between the two observer's findings in eyes with edema. Conclusion: The reproducibility of this technique has been demonstrated in diabetic eyes. This may have useful clinical applications for the quantification of diabetic macular edema and monitoring of laser therapy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Diagnostic accuracy of Heidelberg Retina Tomograph III classifications in a Turkish primary open‐angle glaucoma population

Purpose: This study aimed to evaluate the diagnostic accuracy of Moorfields regression analysis (MRA) and the glaucoma probability score (GPS) in primary open‐angle glaucoma (POAG) and to measure the level of agreement between the two algorithms in classifying eyes as normal or abnormal in a Turkish population. Methods: We prospectively selected 184 healthy subjects and 158 subjects with POAG, who underwent an ophthalmological examination, visual field analysis and imaging with the Heidelberg Retina Tomograph II, using HRT III software, Version 3.0. The diagnostic accuracies of the two classifications were measured when the borderline was taken as either normal (highest specificity criteria) or abnormal (highest sensitivity criteria). The agreement between them was calculated using the unweighted kappa (κ) coefficient. Results: Optic nerve head topographic parameters showed statistically significant differences between the control and POAG groups (p < 0.001). The parameters with the highest area under the receiver operating characteristic curves were global GPS (0.86), cup : disc area (0.85), rim : disc area (0.85) and vertical cup : disc (0.85). According to the highest specificity criteria, MRA had a sensitivity of 67.7% and a specificity of 95.1%, whereas the GPS had a sensitivity of 70.9% and a specificity of 88.0%. According to the highest sensitivity criteria, MRA had a sensitivity of 81.0% and a specificity of 75.0%, whereas the GPS had a sensitivity of 89.2% and a specificity of 57.6%. A moderate agreement of 68% (233 eyes) with a κ coefficient of 0.51 was found between MRA and the GPS. Conclusions: The GPS automated classification showed similar sensitivity to MRA, but considerably lower specificity, when applied in a Turkish population.     

Heidelberg retina tomograph parameters of the optic disc in eyes with progressive retinal nerve fibre layer defects

Purpose: To determine the Heidelberg retina tomograph (HRT) parameters that identify glaucomatous changes in optic nerve head (ONH) topography associated with progression of retinal nerve fibre layer (RNFL) defects. Methods: A total of 68 eyes with open‐angle glaucoma were included in this retrospective study: 34 eyes showed progression of an RNFL defect during the follow‐up period and 34 eyes did not. Successful RNFL photographs and scanning laser tomography examinations with the HRT were taken in all patients at each of three visits. The change in HRT parameter values during follow‐up was calculated. Results: Progression of the RNFL defect was statistically significantly correlated (p = 0.049) with only one topographic ONH parameter, the cup shape measure. The best combination of two parameters (p = 0.009) included the maximum cup depth and the linear cup : disc area ratio; the best combination of three parameters (p = 0.007) included the maximum cup depth, the linear cup : disc area ratio and the horizontal cup : disc area ratio. Sensitivity and specificity values were 52.9% and 73.5%, respectively, for the cup shape measure, 70.6% and 73.5%, respectively, for the two‐parameter combination, and 76.5% and 79.4%, respectively, for the three‐parameter combination. The areas under the receiver operating characteristic curve were 0.617, 0.724 and 0.753, respectively. Conclusions: The results indicate that the HRT parameters may be used to detect small ONH changes associated with progression of the RNFL defect. With the exception of the cup shape measure, the parameters which provide the best correlation with progression differ from those considered optimal for recognizing the presence or absence of glaucoma.     

Optic disc classification by the Heidelberg Retina Tomograph and by physicians with varying experience of glaucoma

Purpose

To compare the diagnostic accuracy of the Heidelberg Retina Tomograph''s (HRT) Moorfields regression analysis (MRA) and glaucoma probability score (GPS) with that of subjective grading of optic disc photographs performed by ophthalmologists with varying experience of glaucoma and by ophthalmology residents.

Methods

Digitized disc photographs and HRT images from 97 glaucoma patients with visual field defects and 138 healthy individuals were classified as either within normal limits (WNL), borderline (BL), or outside normal limits (ONL). Sensitivity and specificity were compared for MRA, GPS, and the physicians. Analyses were also made according to disc size and for advanced visual field loss.

Results

Forty-five physicians participated. When BL results were regarded as normal, sensitivity was significantly higher (P<5%) for both MRA and GPS compared with the average physician, 87%, 79%, and 62%, respectively. Specificity ranged from 86% for MRA to 97% for general ophthalmologists, but the differences were not significant. In eyes with small discs, sensitivity was 75% for MRA, 60% for the average doctor, and 25% for GPS; in eyes with large discs, sensitivity was 100% for both GPS and MRA, but only 68% for physicians.

Conclusion

Our results suggest that sensitivity of MRA is superior to that of the average physician, but not that of glaucoma experts. MRA correctly classified all eyes with advanced glaucoma and showed the best sensitivity in eyes with small optic discs.     

Retinal tomographic measurements in optic disc pit

Background: The aim was to assess the Heidelberg Retina Tomograph II measurements in optic disc pit. Methods: The study included 10 patients with a unilateral optic disc pit. The patients had no other ocular conditions except refractive errors. Normal fellow eyes of the patients were used as a control group. Optic nerve head topographic analyses were performed using a confocal scanning laser ophthalmoscope, Heidelberg Retina Tomograph II (HRT II). Results: The topographic parameters of the eyes with optic disc pit and normal fellow eyes were as follows, respectively: disc area (3.77 ± 1.50 and 3.07 ± 0.83 mm²), cup area (1.99 ± 1.71 and 1.09 ± 0.54 mm²), rim area (1.67 ± 0.55 and 1.87 ± 0.75 mm²), cup volume (0.94 ± 1.24 and 0.34 ± 0.27 mm³), rim volume (0.51 ± 0.40 and 0.55 ± 0.19 mm³), mean cup depth (0.44 ± 0.20 and 0.31 ± 0.11 mm) and mean retinal nerve fibre layer thickness (0.25 ± 0.20 and 0.28 ± 0.59 mm). Eyes with an optic disc pit were found to have significantly larger disc area compared to fellow eyes (p = 0.038). All the other parameters showed no statistically significant interocular differences (p > 0.05). Conclusion: Our study demonstrates that the optic disc pit affects only the disc area measurement in HRT II. Other changes in optic nerve head morphometric parameters were insignificant. The clinician must be careful in the evaluation of HRT II results with respect to optic disc area in a disc with a pit.     

Heidelberg Retina Tomograph (HRT3) in Population-based Epidemiology: Normative Values and Criteria for Glaucomatous Optic Neuropathy

Purpose: To establish normative values for Heidelberg Retina Tomograph (HRT3) variables and to develop HRT3-based criteria for glaucomatous optic neuropathy for epidemiological research in a white population.

Methods: Consecutive participants in the Rotterdam Study were examined with HRT and simultaneous stereoscopic fundus photography (ImageNet) in addition to other ophthalmic examinations including intraocular pressure (IOP) measurements and perimetry. Normative values for all HRT3 variables were determined in participants who met all the following criteria: no glaucomatous visual field loss (GVFL), an IOP of 21mmHg or less, no IOP lowering treatment, and a negative family history of glaucoma. Sensitivity was determined in participants with glaucomatous visual field loss at a fixed high specificity of 97.5% ? a value commonly used in population-based epidemiology.

Results: A total of 2516 participants were included in this study of whom 66 had glaucomatous visual field loss in at least one eye and 1680 fulfilled the criteria for contributing to the normative values. The HRT3 linear cup-disc ratio (LCDR) variable, adjusted for disc area, showed the highest sensitivity, 35%, at the required specificity of 97.5%. The 97.5th percentile of the LCDR was 0.67 for small discs (up to 1.5mm²), 0.73 for medium-sized discs and 0.79 for large discs (above 2.0mm²). The HRT3 Glaucoma Probability Score and previously published linear discriminant functions showed a lower sensitivity than LCDR at this specificity.

Conclusions: At the high specificity of 97.5% as is commonly used in population-based epidemiology, the sensitivity of the HRT3 is low ? albeit not lower than that of the vertical cup-disc ratio as assessed with simultaneous stereoscopic fundus photography and analyzed with the ImageNet software. The LCDR variable, stratified for disc area, seems to be the most suitable variable to develop criteria for glaucomatous optic neuropathy for epidemiological purposes.     

Sensitivity and specificity of Heidelberg Retinal Tomography II parameters in detecting early and moderate glaucomatous damage: effect of disc size

PURPOSE: To determine the efficacy of Heidelberg Retinal Tomography II (HRTII) parameters in differentiating normal eyes from eyes with early or moderate glaucomatous damage. METHODS: HRTII tests were performed on 70 eyes of 70 patients with early or moderate glaucomatous damage, and 70 eyes of 70 healthy subjects. HRTII stereometric parameters, global and sectorial rim area parameters were recorded. Sensitivity and specificity of each parameter were calculated. Cases were divided into three groups according to disc size as large, medium and small, and mean values of parameters in glaucoma and control groups were compared. RESULTS: Mean disc area was larger in the glaucoma group (P < 0.05). There was a significant difference between the two groups for all stereometric parameters, except height variation contour, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross-sectional area stereometric parameters. There was also a significant difference between the groups for global, temporal, superior temporal and inferior temporal rim area parameters. In small discs, however, this difference disappeared in all parameters except temporal rim area and superior temporal rim area sectorial parameters. When all the cases were included, the quartet parameters having the highest specificity (80%) and sensitivity (74.3%) were cup volume, rim volume, cup shape measure and height variation contour parameters. CONCLUSION: Some HRTII parameters have better sensitivity and specificity than the others. It is necessary to pay special attention in evaluating small discs.     

海德堡视网膜断层扫描仪测量正常人视盘参数

目的 :建立正常人群海德堡视网膜断层扫描仪 (Heidelbergretinatomograph ,HRT)视盘参数的正常值 ,明确哪些因素对正常人HRT视盘参数有影响。方法 :选用 10 2例 (13 2只眼 )正常人 ,用HRT进行视盘扫描 ,视盘参数包括视盘面积、视杯面积和容积、盘沿面积和容积、视杯形态、视杯平均深度和最大深度、杯 /盘面积比、沿 /盘面积比、平均视网膜神经纤维层(retinalnervefiberlayer,RNFL)厚度和横截面积、水平C/D和垂直C/D。计算正常人视盘参数范围 ,用直线回归的方法判断视盘大小和年龄对视盘参数的影响。结果 :正常人左右眼和男女间视盘各参数差异无显著意义 (P >0 0 5)。年龄与RNFL厚度及横截面积呈负相关 ,相关系数分别为 -0 2 3 4和 -0 2 3 5,其余各参数与年龄无关。盘沿容积和视杯最大深度不受视盘大小的影响 ,其余各参数均与视盘大小呈线性相关。结论 :HRT可定量检测正常人视盘参数 ;正常人视盘参数变异很大 ,盘沿容积不受视盘大小的影响 ,是一个区分正常与早期青光眼的很好的参数     

Agreement between stereoscopic photographs, clinical assessment, Heidelberg retina tomograph and digital stereoscopic optic disc camera in estimating vertical cup:disc ratio

BACKGROUND: The purpose of the present study was to determine the agreement between stereo photography, Heidelberg retina tomograph (HRT), digital stereoscopic optic disc camera (DISCAM) and ophthalmoscopy in estimating the vertical cup : disc ratio (VCDR). METHODS: One hundred and ninety-nine eyes of 100 subjects from glaucoma clinics were examined by a single glaucoma specialist and the VCDR on ophthalmoscopy was recorded. All eyes were classified as definite glaucoma, glaucoma suspect or no glaucoma based on the entire clinical assessment. Two glaucoma specialists viewed stereo photographs of the eyes separately and independently. A trained technician acquired HRT and DISCAM images. The agreement of VCDR among the four modalities was assessed by the method described by Bland and Altman. RESULTS: Of the 199 eyes, 28.1% were classified as definite glaucoma, 36.2% as glaucoma suspect and 35.7% as no glaucoma. The 2 SD for the agreement between the two glaucoma specialists using stereo photographs was 0.18 VCDR. The 2 SD for the agreement between stereo photographs and HRT, DISCAM and ophthalmoscopy were 0.31, 0.31 and 0.28, respectively. The 2 SD for ophthalmoscopy and HRT was 0.32, for ophthalmoscopy and DISCAM it was 0.32, and for HRT and DISCAM it was 0.22. When the eyes were divided into tertiles according disc size and VCDR, the 2 SD was higher for smaller optic discs (<1.5 mm vertical height) and smaller optic cups (VCDR <0.4). CONCLUSIONS: There was good agreement between VCDR values estimated independently using stereo photographs by the two clinicians. However, when the different modalities were compared using Bland and Altman analysis, all showed poor agreement with a large 2 SD. The agreement was worse for small discs and smaller cups. The VCDR values obtained by the different methods were found not to be interchangeable in a clinic setting.     

Agreement between Heidelberg Retina Tomograph-I and -II in detecting glaucomatous changes using topographic change analysis

Purpose

To evaluate the suitability of including both Heidelberg Retina Tomograph-I (HRT-I) and HRT-II examinations in the same longitudinal series for HRT topographic change analysis (TCA) and to evaluate parabolic error correction (PEC) to improve the agreement between HRT-I and HRT-II examinations.

Methods

A total of 66 eyes from the University of California San Diego Diagnostic Innovations in Glaucoma Study with baseline HRT-I and HRT-II examinations obtained on the same day and ≥3 HRT-II follow-up examinations were included. Two TCA analyses, HRT-I examination at baseline (HRT-I–mixed series) and HRT-II examination at baseline (HRT-II–only series) were compared. Agreement between the HRT-I–mixed and HRT-II–only series were estimated using Bland–Altman plots. Agreement was assessed: (1) using the current HRT software settings (PEC applied only to HRT-II–only series), and (2) modified HRT settings (PEC also applied to HRT-I–mixed series).

Results

With current HRT software settings, the HRT-I–mixed series significantly overestimated change locations (ie, red pixels) compared with the HRT-II–only series as indicated by statistically significant proportional biases in the Bland–Altman analysis. By applying PEC to HRT-I–mixed series there were no statistically significant biases in the TCA parameter estimates compared with the HRT-II–only series.

Conclusion

In some eyes, HRT-I and HRT-II baseline examinations are not interchangeable in TCA analysis without parabolic error correction. HRT-I–mixed series detected more changes characteristic of glaucoma when there were only minimal changes in the HRT-II–only series. Our results suggest that in the majority of cases, with PEC, HRT-I examinations may be included in a longitudinal series containing HRT-II examinations.