Comparison of optic disk and retinal nerve fiber layer thickness in nonglaucomatous and glaucomatous patients with high myopia

PURPOSE: To assess the optic nerve head (ONH) by optical coherence tomography (OCT), confocal scanning laser ophthalmoscopy (CSLO), and the retinal nerve fiber layer (RNFL) by OCT and scanning laser polarimetry (GDx) in highly myopic subjects. DESIGN: Observational cross-sectional study. METHODS: Thirty-five eyes of highly myopic individuals without glaucoma and 17 eyes of highly myopic patients with glaucoma were included in this study. All patients had myopia higher than 5.0 diopters and ocular axial length higher than 25 mm. In those patients without glaucoma, the intraocular pressure (IOP) was less than 21 mm Hg. RESULTS: Mean (SD) OCT cup-to-disk area ratio was 0.45 (0.30) and 0.58 (0.29) in the nonglaucomatous and glaucomatous subjects, respectively (P = .22); CSLO cup-to-disk area ratio was 0.27 (0.27) and 0.24 (0.23), respectively (P = .75); and OCT-RNFL was 65.2 (26.2) microm and 56.8 (28.6) microm (P = .43). CONCLUSIONS: OCT, CSLO, and GDx are not useful to discriminate nonglaucomatous and glaucomatous subjects that have high myopia.     

正常眼压性青光眼与高眼压性青光眼视神经图像分析的对比研究

目的 探讨正常眼压性青光眼 (normal-tension glaucoma, NTG)与高眼压性青光眼(high-tension glaucoma, HTG)视盘和视神经纤维层(retinal nerve fiber layer, RNFL)损害的差异。 方法 选择具有青光眼性视神经损害或RNFL缺损、相应的视野缺损的青光眼患者,NTG至少2次24 h眼压曲线和多次眼压测量均≤21 mm Hg(1 mm Hg =0.133 kPa)，HTG的眼压至少2次测量≥25 mm Hg。患者进行详细的眼科检查，同时用扫描激光偏振仪(scanning laser polarimetry, SLP)、光学相干断层扫描（optical coherence tomography, OCT）和海德堡视网膜成像仪(Heidelberg retinal tomography, HRT)定量测定视盘形态和RNFL厚度。比较两组视盘总体和相同象限测量参数。 结果 30例 NTG和 19例 HTG (共49只眼)患者的平均年龄分别为(59.6±8.6)岁(39～71岁)和(59.2±12.3)岁(36～75岁)。两组间视野缺损的平均偏差(mean deviation, MD)差异不显著(P＞0.05)。HRT测量的视盘 C/D面积比，除鼻侧象限外,NTG者视盘总体和上、下、颞侧3个象限均显著大于HTG者(P＜0.05 ),而盘缘面积小于HTG者(P＜0.05)；两组间其他视盘参数差异不显著。3种激光扫描技术所测定的总体和象限RNFL厚度，两组间差异不显著。 结论 NTG趋向大 C/D面积比和窄盘缘面积。RNFL缺损的形态分布须更精细和节段性分析。 (中华眼底病杂志, 2002, 18: 109-112)     

Deformation of the rodent optic nerve head and peripapillary structures during acute intraocular pressure elevation

PURPOSE. To evaluate the effect of acutely elevated intraocular pressure (IOP) on retinal thickness and optic nerve head (ONH) structure in the rat eye by spectral domain-optical coherence tomography (SD-OCT). METHODS. Fourteen adult male Brown-Norway rats were studied under anesthesia (ketamine/xylazine/acepromazine, 55:5:1 mg/kg intramuscularly). Both eyes were imaged by SD-OCT on two baseline occasions several weeks before and again 2 and 4 weeks after the acute IOP imaging session. During the acute IOP session, SD-OCT imaging was performed 10 minutes after IOP was manometrically set at 15 mm Hg and then at 10, 30, and 60 minutes after IOP had been elevated to 50 mm Hg (n = 8) and again 10 and 30 minutes after IOP had been lowered back to 15 mm Hg (recovery). In two additional groups, IOP elevation was set to 70 mm Hg (n = 4) or 40 mm Hg (n = 2). Acute IOP results are reported for a pattern of 49 horizontal B-scans spanning a 20° square and follow-up results for peripapillary circular B-scans. Retinal and retinal nerve fiber layer (RNFL) thicknesses were measured with custom software by manual image segmentation. Friedman and Dunn's tests were used to assess acute and longer-term effects of acute IOP elevation. RESULTS. Acute IOP elevation to 50 mm Hg caused rapid (within seconds) deformation of the ONH and peripapillary structures, including posterior displacement of the ONH surface and outward bowing of peripapillary tissue; retinal thickness decreased progressively from 10 to 30 to 60 minutes by 16%, 18%, and 20% within the area of Bruch's membrane opening (BMO; P < 0.0001) by 8%, 9%, and 11% within the central 10° (excluding the BMO; P < 0.0001) but only by 1%, 2%, and 2.4% beyond the central 10° (P < 0.0001). Recovery was progressive and nearly complete by 30 minutes. Acute IOP elevation to 40 and 70 mm Hg produced similar structural changes, but 70 mm Hg also interfered with retinal blood flow. There were no changes in peripapillary retinal or RNFL thickness (P = 0.08 and P = 0.16, respectively) measured 2 and 4 weeks after acute elevation to 50 mm Hg. CONCLUSIONS. Acute IOP elevation in the rodent eye causes rapid, reversible posterior deformation of the ONH and thinning of the peripapillary retina, with only minimal retinal thinning beyond 5° of the ONH. No permanent changes in peripapillary retinal or RNFL thickness (for up to 1 month of follow-up) were caused by 60 minutes of IOP elevation to 50 mm Hg.     

Retinal nerve fiber layer measurements using laser scanning polarimetry in different stages of glaucomatous optic nerve damage

PURPOSE: To evaluate the diagnostic value of polarimetric measurements of the retinal nerve fiber layer (RNFL) thickness in different stages of glaucomatous optic nerve damage. METHODS: The study included 92 eyes of 46 controls (age 41.0+/-13.7 years) and a heterogeneous group of 232 eyes of 135 patients with different stages of glaucomatous optic nerve damage (age 54.0+/-10.2 years; 68 patients with primary open-angle glaucoma, 56 with normal-pressure glaucoma and 11 patients with secondary glaucoma due to primary dispersion syndrome or pseudoexfoliation syndrome). All control subjects and patients underwent complete ophthalmological examinations including scanning laser polarimetry of the RNFL using the GDx (Laser Diagnostic Technologies, San Diego, Calif.) and 15 degrees color stereo optic disc photographs. Only subjects and patients with disc area less than 3.4 mm(2) were included in the study. The total glaucoma group were divided into four subgroups according to the morphological criteria of the neuroretinal rim. RESULTS: The stage of morphological glaucomatous optic nerve damage was classified as follows: stage 0: n=92, stage 1: n=103, stage 2: n=65, stage 3: n=40, and stage 4: n=19. Differences in mean polarimetric retardation between controls and eyes with glaucoma were significant for all parameters except the variable symmetry. The most significant differences between controls and eyes with glaucomatous optic nerve damage were found with the "number" variable assigned by the neural network analysis ( P<0.001). With increasing stage of glaucomatous optic nerve damage, separation of the variable "the number" increased significantly. At a predetermined specificity of 90% the sensitivity of the groups with different stages of morphological glaucomatous optic nerve damage increased from 32% for stage 1 to 90% for stage 4. CONCLUSION: Polarimetric measurement of the RNFL thickness is significantly associated with morphological glaucomatous optic nerve damage. The fast performance, easy handling, and low cost of RNFL polarimetry mean that it can be included in the routine examination of glaucoma patients. Further study and refinement of this technique are indicated to improve its usefulness in both clinical diagnosis and in population-based case identification.     

The relationship between optical coherence tomography and scanning laser polarimetry measurements in glaucoma

PURPOSE: To investigate the relationship between optical coherence tomography (OCT) and scanning laser polarimetry (SLP) in measuring peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes. METHODS: Fifty glaucomatous eyes were evaluated in this study. Evaluations were analyzed two ways. First, parameters of the Stratus OCT (average thickness, superior/inferior average) and GDx VCC (TSNIT average, nerve fiber indicator (NFI), superior/inferior average) were correlated using the Pearson's correlation coefficient (r). Secondly, comparison (r) of these parameters was completed using the mean deviation (MD) of visual field defect. RESULTS: The following parameters were found to be significantly correlated (P < 0.005). TSNIT average/average thickness (r = 0.673), NFI/average thickness (r = -0.742), superior average (r = 0.841), and inferior average (r = 0.736). In the correlation analysis using the severity of visual field defect, all these parameters had statistically meaningful correlations (P < 0.005). CONCLUSIONS: GDx VCC and Stratus OCT are highly correlated in glaucomatous eyes. Therefore, peripapillary RNFL thickness measured by Stratus OCT and GDx VCC may be equally helpful in the diagnosis of glaucoma.     

Scanning laser polarimetry versus frequency-doubling perimetry and conventional threshold perimetry: changes during a 12-month follow-up in preperimetric glaucoma. A pilot study.

PURPOSE: To evaluate the possibility for detecting the progression in preperimetric primary open angle glaucoma (POAG) using scanning laser polarimetry (SLP), frequency-doubling technology (FDT), and conventional automated perimetry (AP). PATIENTS AND METHODS: 22 eyes of 11 preperimetric POAG patients were evaluated using SLP (Nerve Fiber Analyzer, GDx), AP (Humphrey 24-2 threshold test) and FDT (30 degrees threshold test). All eyes had intraocular pressure (IOP) higher than 21 mmHg before treatment, but were consistently lower than 22 mm Hg with unchanged topical medication before and during the study. At the initial evaluation session optic nerve heads showed mild glaucomatous changes but the visual fields were normal (MD better than 2.0 dB, Glaucoma Hemifield Test: within normal limits or borderline). AP and FDT measurements were repeated 6 months later, and all three tests were repeated 12 months after the first investigation. RESULTS: IOP, AP and FDT measurements showed no statistically significant changes during the 12-month follow up period. In contrast to this, a tendency for a glaucomatous type decrease was seen with SLP in the retinal nerve fibre layer (RNFL) thickness parameters (mean superior and inferior sector thickness values, ellipse average thickness and maximal modulation). The mean decrease of RNFL thickness in the superior and inferior sectors was 2.77 microm and 2.48 microm, respectively. Using the two-way nested ANOVA, which considers the relation between the right and left eyes of the subjects, the decrease was statistically significant (p=0.021) for the inferior sector RNFL thickness. CONCLUSION: The results suggest that scanning laser polarimetry is a useful technique to detect and measure glaucomatous progression in early glaucoma. Scanning laser polarimetry of the RNFL may help to detect and quantify early progression even if worsening is not seen with perimetry and FDT tests.     

Impact of diabetic retinopathy on quantitative retinal nerve fiber layer measurement and glaucoma screening

PURPOSE: To investigate the impact of diabetic retinopathy on quantitative retinal nerve fiber layer (RNFL) assessment and diagnostic power for glaucoma by scanning laser polarimetry (GDx-VCC) and optical coherence tomography (StratusOCT). METHODS: The individual RNFL parameters of GDx and OCT were obtained for 170 eyes (one eye from each of 170 subjects [45 healthy, 47 glaucoma, 40 diabetes, and 38 glaucoma with diabetes]) and were compared among the four groups. Diabetic eyes had mild to moderate nonproliferative diabetic retinopathy (NPDR) without maculopathy. In glaucomatous eyes with or without diabetes, the ability to discriminate glaucoma was assessed by the areas under the receiver operating characteristic curves (AUROCs) and the sensitivities at more than 80% and 90% of specificities for each technique. RESULTS: Using GDx-VCC, significant differences (P < 0.05) in RNFL measurement parameters were found for all comparisons except those between glaucomatous eyes with diabetes and without diabetes. StratusOCT parameters did not detect significant differences between age-matched healthy and diabetic eyes. Among the parameters included, the nerve fiber indicator (NFI) of GDx-VCC and the inferior quadrant thickness (IQT) of StratusOCT had the largest AUROCs and sensitivities at specificities greater than 80%: NFI (0.912, 86%) and IQT (0.902, 85%) in glaucomatous eyes with diabetes; NFI (0.935, 92%) and IQT (0.921, 91%) in simple glaucomatous eyes. CONCLUSIONS: Mild to moderate NPDR causes a quantitative discrepancy in RNFL measurements between GDx-VCC and StratusOCT in simple diabetic eyes. However, mild to moderate glaucomatous optic neuropathy can be highly discriminated by the two imaging devices in eyes with diabetic retinopathy.     

Diabetes-associated retinal nerve fiber damage evaluated with scanning laser polarimetry

PURPOSE: To evaluate retinal nerve fiber layer (RNFL) thickness in patients with diabetes mellitus compared with age-matched normal control subjects, to assess the correlation between the RNFL thickness and the severity of retinopathy, and to investigate whether diabetes mellitus is a potential source of abnormal results in glaucoma screening or evaluation with scanning laser polarimetry (SLP). DESIGN: Cross-sectional analysis of normal and diabetic eyes. METHODS: setting: Institutional clinical study. patients: One hundred twenty-eight subjects with type 2 diabetes mellitus and 50 age-matched normal control subjects without glaucoma or glaucoma-suspect. All patients underwent imaging with SLP and repeatable automated perimetry. Subjects with diabetes mellitus were classified into four stages on the basis of the severity of retinopathy that was assessed by dilated funduscopic examination, high-quality fundus color photography, and fluorescein angiography. MAIN OUTCOME MEASURES: The SLP (GDx VCC software, version 5.5.0) parameters. RESULTS: The RNFL thickness in patients with diabetes mellitus was reduced significantly compared with age-matched normal control eyes (P < .01). Moreover, all RNFL thickness parameters of the GDx VCC software decreased significantly as an exacerbation of diabetic retinopathy (P = .0019, P = .0045, P = .0010 for temporal-superior-nasal-inferior-temporal (TSNIT) average, superior average, inferior average, respectively). The nerve fiber indicator also increased significantly (P < .0001), despite an absence of glaucomatous optic nerve damages. CONCLUSION: The RNFL thickness in type 2 diabetes mellitus, which was measured by GDx VCC software, significantly decreased with the severity of diabetic retinopathy. The presence of diabetes mellitus can be a source of false-positive results and overestimation of glaucomatous optic neuropathy when eyes are screened with GDx VCC software.     

Comparison between GDx VCC scanning laser polarimetry and Stratus OCT optical coherence tomography in the diagnosis of chronic glaucoma

PURPOSE: To compare the abilities of scanning laser polarimetry with the variable corneal compensator (GDx VCC) with those of optical coherence tomography (Stratus OCT) in discriminating between healthy and early-to-moderate perimetric glaucomatous eyes. METHODS: A total of 95 glaucomatous patients (mean deviation - 3.7 +/- 3.0 dB, pattern standard deviation 4.5 +/- 2.7 dB) and 62 control subjects underwent imaging by the GDx VCC and Stratus OCT using both optic nerve head (ONH) and retinal nerve fibre layer (RNFL) scan protocols. One eye per patient was considered. Sensitivity at > or = 90% specificity and area under the receiver operating characteristic curve (AROC) were calculated for each GDx VCC and Stratus OCT index. RESULTS: The largest AROCs with Stratus OCT were associated with cup : disc area ratio (0.88) for ONH scan indices, and with average thickness (0.84) for RNFL scan indices. The nerve fibre indicator provided the greatest AROC for the GDx VCC indices (0.85). CONCLUSIONS: Both the GDx VCC and Stratus OCT instruments were shown to be useful in the detection of glaucomatous damage. The best performing indices for the GDx VCC and Stratus OCT with both ONH and RNFL scans gave similar AROCs, showing a moderate sensitivity in early-to-moderate glaucoma patients.     

Comparison of Goldmann applanation tonometry, rebound tonometry and dynamic contour tonometry in normal and glaucomatous eyes

AIM: To compare the intraocular pressure (IOP) measurements obtained with the rebound tonometry (RT), dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in normal and glaucomatous eyes and investigate the effects of central corneal thickness (CCT) and corneal curvature (CC) on IOP measurements. METHODS: One hundred and twenty-four eyes of 124 subjects were enrolled in this cross-sectional study. Fifty-six of participants were healthy individuals and 68 of them were glaucomatous patients. IOP was measured on each subject always in the same order, ICare RT-Pascal DCT-GAT, after a minimum interval of 10min between measurements. CCT and CC were measured using a rotating Scheimpflug camera before the IOP measurements in all subjects. One way repeated measures ANOVA, Pearson correlation coefficient and regression analysis, and Bland-Altman analysis was used for the statistical assessment. RESULTS: Mean IOP for all enrolled eyes was 16.00±3.80 mm Hg for GAT, 16.99±4.91 mm Hg for RT, and 20.40±4.44 mm Hg for DCT. Mean differences between GAT and RT was -1.75±3.41 mm Hg in normal (P<0.001) and -0.37±3.00 mm Hg in glaucomatous eyes (P=0.563). Mean differences between GAT and DCT was -4.06±3.42 mm Hg in normal (P<0.001) and -4.67±3.12 mm Hg in glaucomatous eyes (P<0.001). GAT and RT were significantly positive correlated with CCT in normal (r=0.317, P=0.017 and r=0.576, P<0.001, respectively) and glaucomatous eyes (r=0.290, P=0.016 and r=0.351, P=0.003, respectively). DCT was also significantly positive correlated with CCT in normal eyes (r=0.424, P=0.001) but not in glaucomatous eyes (r=0.170, P=0.165). All tonometers were unaffected by CC. CONCLUSION: IOP measurements by RT and DCT were significantly higher than GAT. DCT has highest IOP measurements among these tonometers. RT was most influenced tonometer from CCT although all tonometers were significantly positive correlated with CCT except DCT in glaucomatous eyes. CC did not influence IOP measurements.     

Comparison of intraocular pressure readings with Perkins, Tonopen, iCare 200, and iCare Home to manometry in cadaveric eyes

AIM: To compare intraocular pressure (IOP) readings obtained with Perkins tonometry, iCare Home, iCare 200, and Tonopen to IOP readings obtained with the manometer of a perfusion system to assess the accuracy and reproducibility of each method of tonometry at set pressures. METHODS: The IOP of human cadaveric eyes (n=2) was measured using a manometer inserted into the eye through the optic nerve. IOP measurements were obtained using a Perkins tonometer, iCare Home, iCare 200, and Tonopen. These measurements were compared to set point IOP measurements of a manometer to determine accuracy and reproducibility of each device. RESULTS: Mean IOP readings obtained with the Perkins tonometer compared to manometer readings demonstrated a difference of -1.0±5.0 mm Hg (P=0.45), indicating a lower reading on average than manometery although not significant. Mean IOP difference between iCare 200 and manometer was 5.3±2.2 mm Hg (P<0.0001). Mean difference in IOP between iCare Home and manometer was 3.5±2.4 mm Hg (P=0.0004). Mean IOP difference compared to manometer was 4.6±4.0 mm Hg for the Tonopen (P<0.0001). IOP measurements obtained with the Perkins tonometer demonstrated a standard deviation of 5.0 mm Hg while the Tonopen measurements demonstrated a 4.0 mm Hg standard deviation. In comparison, iCare 200 and iCare Home demonstrated 2.2 and 2.4 mm Hg standard deviation, respectively. CONCLUSION: Applanation tonometry produces more accurate IOP readings than rebound tonometry or Tonopen, however it demonstrates greater variability than the other forms of tonometry. Rebound tonometry is more reproducible but tends to over-estimate IOP.     

Can frequency-doubling technology and short-wavelength automated perimetries detect visual field defects before standard automated perimetry in patients with preperimetric glaucoma?

PURPOSE: To assess the ability of frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) to detect glaucomatous damage in preperimetric glaucoma subjects. PARTICIPANTS: Two hundred seventy-eight eyes of 278 subjects categorized as normal eyes [n=98; intraocular pressure <20 mm Hg, normal optic disc appearance, and standard automated perimetry (SAP)]; preperimetric glaucoma eyes (n=109; normal SAP and retinal nerve fiber layer defects or localized optic disc notching and thinning); and glaucoma patients (n=71; intraocular pressure >21 mm Hg, optic disc compatible with glaucoma, and abnormal SAP). METHODS: The preperimetric glaucoma group underwent at least 2 reliable full-threshold 24-2 Humphrey SAPs, full-threshold C-20 FDT, full-threshold 24-2 SWAP, optic disc topography using the Heidelberg Retina Tomograph II, laser polarimetry using the GDx VCC, and Optical Coherence Tomography (Zeiss Stratus OCT 3000). Receiver operating characteristic curves were plotted for the main Heidelberg Retina Tomograph, Optical Coherence Tomography, and GDx VCC parameters for the normal and glaucoma patients. The area under the receiver operating characteristic curve was used to determine the parameters indicating glaucomatous damage in the optic disc or retinal nerve fiber layer, which were used to establish additional subgroups of patients with preperimetric glaucoma. FDT and SWAP sensitivities were calculated for the patient subsets with structural damage and normal SAP. RESULTS: At least 20% of the patients with preperimetric glaucoma demonstrated functional losses in FDT and SWAP. The more severe the structural damage, the greater the sensitivity for detecting glaucomatous visual field losses. CONCLUSIONS: FDT and SWAP detect functional losses in cases of suspected glaucoma before glaucomatous losses detected by SAP.     

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

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

Effects of chronic elevated intraocular pressure on parameters of optical coherence tomography in rhesus monkeys

AIM: To determine the progression of parameters from optical coherence tomography (OCT) in chronic elevated intraocular pressure (IOP) monkeys. METHODS: A chronic elevated IOP model of rhesus monkeys was induced by laser photocoagulation. Representative OCT parameters, including the average and four-quadrant retinal nerve fiber layer (RNFL) thickness, and parameters from optic nerve head (ONH) analysis were collected before and after laser treatments biweekly for up to 28wk. The performance of each parameter for early progression detection was analyzed. The progressive trends toward elevated IOP were analyzed using a linear mixed-effects model. RESULTS: There were 10 successfully maintained high IOP eyes in 7 monkeys. The follow-up time was 24±5.37wk. With cumulative IOP elevation, the cup area, rim area and C/D area ratio were statistically significantly changed as early as 2wk after elevated IOP induction (P<0.05). The quadrant RNFL thickness changed at 6wk after high IOP induction, and the superior and inferior RNFL thicknesses exhibited more obvious reductions than other quadrants. The average RNFL thickness was the last one to show a significant decrease at 8wk. CONCLUSION: The parameters of ONH are most sensitive to elevated IOP in a primate glaucomatous model. These findings suggest that we should focus on those parameters instead of RNFL thickness in patients with elevated IOP, as they might present with earlier glaucomatous changes.     

Glaucoma detection using the GDx nerve fiber analyzer and the retinal thickness analyzer (RTA)

PURPOSE: To compare the ability of the nerve fiber analyzer (GDx) and the retinal thickness analyzer (RTA) to discriminate between glaucomatous and healthy eyes. METHODS: Thirty-seven glaucoma patients (early to moderate severity) and 34 healthy controls were included. Glaucoma patients were defined as those with two repeatable abnormal visual fields by automated perimetry within 1 year. All subjects were examined with a GDx scanning laser polarimeter and RTA. Twelve GDx retinal nerve fiber layer parameters and 12 RTA optic disk topography parameters were obtained. GDx and RTA measurements were compared between both experimental groups using t-tests. Areas under the receiver operating characteristic curves (AUROC) for discriminating between healthy and glaucomatous eyes using GDx and RTA parameters were calculated and compared, and sensitivities at >or=80% and >or=95% specificity were reported. RESULTS: Statistically significant differences between glaucomatous and healthy eyes were found for most GDx and RTA parameters. For GDx, the parameter with the largest AUROC for discriminating between healthy and glaucomatous eyes was the number (AUROC = 0.91, sensitivity = 85% at specificity = 84%, sensitivity = 73% at specificity = 95%). For RTA, the parameter with the largest AUROC was mean cup depth (AUROC = 0.79, sensitivity = 61% at specificity = 82%, sensitivity = 33% at specificity = 95%). The AUROC for the GDx number was significantly larger than the AUROC for RTA mean cup depth (p<0.05). CONCLUSIONS: GDx showed better discrimination and better sensitivities at fixed specificities than RTA. The currently available RTA optic disk analysis software likely cannot replace GDx RNFL analysis software for successful glaucoma diagnosis.     

Morphometric evaluation of changes with time in optic disc structure and thickness of retinal nerve fibre layer in chronic ocular hypertensive monkeys

We examined the time course of changes in optic disc structure by means of a scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT) in ocular hypertensive (experimental glaucoma) monkeys, and clarified the relationships between the histological RNFL thickness and HRT parameters. Further, the time course of changes in retinal nerve fiber layer (RNFL) thickness in individual eyes was measured using a scanning laser polarimeter with fixed corneal polarization compensator (GDx FCC). In the present study, two separate experiments were carried out. A chronic intraocular pressure (IOP) elevation was induced by laser trabeculoplasty in the left eye in 11 cynomolgus monkeys. In Experiment 1, the HRT and GDx parameters were measured 12 weeks after the laser treatment in 10 eyes in five monkeys. In Experiment 2, the time course of changes in the HRT and GDx parameters was examined before and 1, 3, 4, 5, 6, 8, 10, 12, 14, and 16 weeks after the laser treatment in 12 eyes in six monkeys. The retardation values (thickness parameters) obtained from the GDx were used to derive thickness and ratio parameters in the superior, inferior, nasal and temporal quadrants. Ratio parameters were expressed as a ratio of superior and inferior quadrant to nasal quadrant. After the last measurements, each eye was enucleated, and retinal cross sections were prepared for histological analysis. In the left (hypertensive) eyes, IOP was persistently elevated throughout the observation periods in both Experiments 1 and 2. In the HRT measurements in Experiment 1, seven out of eight global topographic parameters (exception, disc area) were statistically different between the hypertensive and control eyes 12 weeks after the laser treatment. In Experiment 2, the HRT parameters changed in a time-dependent manner, but each of them almost plateaued at about 4 weeks after the laser treatment. Significant correlations were seen between the histological mean RNFL thickness at 1.5 disc diameters from the optic disc margin and the HRT parameters in 21 eyes from 11 monkeys in Experiments 1 and 2. Especially good correlations with histological mean RNFL thickness were seen for the rim volume and cup volume. In Experiment 1, good correlations were found between GDx ratio parameters and histological RNFL thickness in individual right control eyes (n=5). In individual left experimental glaucoma eyes of Experiment 2 (n=6), GDx ratio parameters declined in a time-dependent manner alongside the IOP elevation. In conclusion, alongside the IOP elevation, time-related changes in optic disc topography and RNFL thickness were demonstrated in monkey eyes using HRT and GDx. HRT (rim and cup) parameters showed good correlations with histological RNFL thickness, and significant interrelations.     

Objective retinal nerve fiber laser assessment by scanning laser polarimetry in patients with chiasmal compression

PURPOSE: To assess the evaluation ability of retinal nerve fiber layer (RNFL) in patients with visual tracts' compression and to assess the correlation between visual field loss and changes in RNFL. MATERIAL AND METHODS: Polarimetric RNFL analysis (scanning laser polarimeter- NFA/GDx, software version 1.0.16, LDT(inc)) and kinetic perimetry were done in 41 eyes with different types of optic chiasma compression and in 40 healthy eyes, age matched controls. RESULTS: In eyes with optic chiasma compression most of the GDx parameters were statistically different from the control group (P<0.05). In eyes with normal visual fields and with optic chiasma compression most of GDx parameters were statistically different from the other analyzed groups. CONCLUSIONS: GDx may be a helpful tool in diagnosis of optic chiasma diseases. GDx is a useful visual prognostic indicator in the preoperative assessment of optic chiasma compression. Objective RNFL assessment is especially important in patients with serious visual field loss and poor visual acuity.     

Efficacy of ripasudil in reducing intraocular pressure and medication score for ocular hypertension with inflammation and corticosteroid

AIM: To investigate the efficacy of ripasudil, a Rho kinase inhibitor, in reducing intraocular pressure (IOP) and medication scores of anti-glaucoma drugs in patients with ocular hypertension with inflammation and corticosteroid. METHODS: The study included 11 patients diagnosed with ocular hypertension with inflammation and corticosteroid, all of whom were prescribed ripasudil eye drops and followed up for at least 2y after the initiation of treatment. IOP was measured using a non-contact tonometer before enrollment and at each follow-up visit. The medication score of glaucoma eye drops was calculated for each patient. RESULTS: The mean IOP (26.4±2.9 mm Hg before treatment) significantly decreased after ripasudil therapy (13.7±3.3 mm Hg at 3mo) and remained stable in the low-teens during the 2-year follow-up period (P<0.0001). A significant decrease in the medication score was observed at 12mo or later after the initiation of ripasudil therapy (P<0.05). Both baseline medication scores and glaucomatous optic disc change rates were significantly higher in the five eyes that required glaucoma surgery during the 2-year observation period than the 10 eyes that did not require surgery. CONCLUSION: Our results demonstrate the efficacy of ripasudil, in reducing IOP and the medication score over a 2-year treatment period in patients with ocular hypertension with inflammation and corticosteroid. Our findings also suggest that ripasudil could reduce the IOP in uveitic glaucoma patients with both lower baseline medication score and lower glaucomatous optic disc change rate.     

Correlation between confocal scanning laser ophthalmoscopy and scanning laser polarimetry in open angle glaucoma

PURPOSE: To correlate the findings of confocal scanning laser ophthalmoscopy and scanning laser polarimetry in diagnosed cases of glaucoma with established visual field defects. METHODS: A total of 53 diagnosed cases of primary open angle glaucoma that had at least two recorded of IOP more than 21 mm Hg on Goldmann applanation tonometry, open angles on gonioscopy and glaucomatous visual field defects on automated perimetry, were examined by confocal scanning laser ophthalmoscopy (HRT-II) and scanning laser polarimetry (GDx-NFA), in random order. RESULTS: The number on GDx advanced analysis had a significant (p < 0.05) correlation with the rim area (r = -0.279; p = 0.043), cup area (r = 0.311; p = 0.023) and the vertical cup: disc ratio (r = 0.376; p = 0.006). The correlation between HRT-II stereometric parameters and GDx advanced analysis parameters was significant (p < 0.05) for more parameters targeting the inferior pole of the disc than the superior pole. Numerically, the worst values of GDx parameters were associated with a worse result on Moorfields regression analysis, but there was poor agreement between the diagnostic labels like within or outside normal limits as obtained on GDx and HRT-II. CONCLUSIONS: Nerve fiber loss as detected on GDx correlates well with topographic optic nerve head changes as measured with the HRT-II. However, automated diagnosis on the two machines showed poor agreement.     

Retinal nerve fiber layer thickness changes after an acute increase in intraocular pressure

PURPOSE: To determine whether the increase in intraocular pressure (IOP) for 45 seconds during laser in situ keratomileusis (LASIK) suction can induce a decrease in retinal nerve fiber layer thickness (RNFLT) assessed by a confocal scanning laser polarimeter. SETTING: Jules Gonin Hospital, University of Lausanne, Lausanne, Switzerland. METHODS: Eleven normal volunteers were enrolled in the study. The optic disc of each eye was analyzed by the GDx(R) Nerve Fiber Analyzer (Laser Diagnostic Technologies, Inc.), version 1.0.14. Using the standard circle that appears as a 10-pixel green circle on the GDx display, the system assessed the RNFLT at 1.75 disc diameter from the outer edge of the optic nerve head. To further evaluate the possible retinal nerve fiber layer (RNFL) loss, the 360-degree circumference was divided into 36 segments measuring 10 degrees each and the RNFLT was calculated for each sector. All subjects had a GDx assessment before 100 mm Hg ocular compression of 1 eye for 45 seconds and then 2 minutes and 1 month after compression. RESULTS: Before compression, the mean RNFLT was 69.09 microm +/- 10.96 (SD); it was 69.27 +/- 10.98 microm after 2 minutes and 67.00 +/- 10.58 microm after 1 month. No statistically significant difference was found between the before and after measurements. CONCLUSION: A 45-second acute increase in IOP, such as during LASIK suction, did not decrease the RNFLT in normal eyes.