Localised wedge shaped defects of the retinal nerve fibre layer in glaucoma.

Glaucoma can be associated with a diffuse or localised loss of the retinal nerve fibre layer (RNFL). This study evaluated the wedge shaped localised RNFL defects. Red free wide angle RNFL photographs of 421 patients with glaucoma and 193 normal subjects were examined. Localised RNFL defects were described for one eye of the normal group and for 20% of the patients with glaucoma. They were usually located in the inferior temporal and superior temporal fundus regions. Within the glaucoma group, localised RNFL defects occurred most often (p < 0.05) in normal pressure glaucoma, followed by primary open angle glaucoma, and finally secondary open angle glaucoma. They were positively associated with disc haemorrhages. The localised RNFL defects had a high specificity to indicate optic nerve damage. The nerve fibre layer defects occurring more likely in mild rather than advanced glaucoma, they were helpful in the diagnosis of early glaucoma. The association between localised RNFL defects and disc haemorrhages and the varying frequency of localised RNFL defects in different types of glaucoma may be important diagnostically and pathogenetically.     

Wedge-shaped retinal nerve fiber layer defects in experimental glaucoma preliminary report

Many investigators have reported that abnormalities in the retinal nerve fiber layer may be the earliest sign of primary open-angle glaucoma. We attempted to create defects in the retinal nerve fiber layer in experimentally induced glaucoma and to examine their histology. By repeated circumferential argon laser photocoagulation of the trabecular meshwork of normal cynomolgus monkeys, we succeeded in causing a continuous increase in intraocular pressure (IOP). During the course of this experiment, cupping of the optic nerve head, wedge-shaped retinal nerve fiber layer defects, and halo glaucomatosus developed, all of which are defects that are similar to those seen clinically in primary open-angle glaucoma. The IOP required for this fundus change was 25, 35, and 43 mmHg, indicating great individual variation. Histological examination revealed localized degeneration, loss of axon bundles, and diffuse thinning of the nerve fiber layer in the area of these wedge-shaped defects in the retinal nerve fiber layer. These results may indicate that the optic-nerve-damaging mechanism, both localized and generalized, is the same in the cynomolgus monkey and in man.     

Morphologic changes in chronic high-pressure experimental glaucoma in rhesus monkeys

PURPOSE: To investigate morphologic changes in the posterior segment of the eye and optic nerve head (ONH) in rhesus monkeys with experimental glaucoma, and to evaluate the effect of age and vascular disease on the glaucomatous damage. METHODS: This study was conducted in 36 eyes of rhesus monkeys 11 to 24 years of age. Experimental glaucoma was produced by laser photocoagulation of the anterior chamber angle in 28 eyes, and the remaining 8 eyes served as the nonglaucomatous group. Of the 28 glaucomatous eyes, 19 belonged to animals with experimental atherosclerosis and chronic arterial hypertension (A-H group); the remaining 9 had no A-H (non-AH group). Among the 8 eyes without glaucoma, 5 belonged to A-H animals and the remaining 3 to animals without A-H. All eyes underwent IOP measurements and fundus photography before laser photocoagulation and serially thereafter for 4 to 60 months (median 22.5 months). After enucleation, eyes were fixed in formalin for light microscopic studies. Morphologic abnormalities were evaluated and graded. Correlation analyses between morphologic parameters and clinical data were performed. RESULTS: The highest IOP ranged from 44 to 80 mmHg, but during the follow-up period median IOP was mostly 28 mmHg (mean 27+/-4.8 mmHg). On histopathologic examination, the eyes showed moderate to severe atrophy of the temporal peripapillary choroid (67%), choriocapillaris (70%), and RPE (12%); axonal atrophy in the retinal nerve fiber layer (85%), prelaminar region (69%), lamina cribrosa (66%), and retrolaminar region (82%); fibrous septal thickening in the lamina cribrosa (77%) and retrolaminar region (86%); bowing backward of the lamina cribrosa (77%); overall tissue atrophy in the prelaminar region (81%); and retinal ganglion cell atrophy (74%). The data showed a positive correlation between the ONH damage and atrophic changes in the temporal peripapillary choroid, and suggested greater damage in animals with A-H than in those without A-H. CONCLUSION: Vascular disease may influence glaucomatous damage in the ONH, as damage in the ONH was greater in animals with A-H than in those without A-H. A similar relationship also may exist between age and glaucomatous damage, but this needs to be investigated further in a larger study. It is postulated that the bowing back of the lamina cribrosa seen in optic disc cupping is produced by retrolaminar septal fibrosis and axonal loss. Although elevated IOP no doubt played an important role, the data suggest that the glaucomatous changes that were observed in this study are not simply mechanical in nature (due to the raised IOP), but may represent a multifactorial phenomenon.     

Multiple defects in the retinal nerve fiber layer in glaucoma

We investigated the parameters that correlated with multiple defects in the retinal nerve fiber layer in 77 human eyes with normal-tension glaucoma, 110 with chronic high-tension glaucoma, and 102 control eyes. All 187 glaucomatous eyes had a nerve defect that was multiple in 20 cases. Correlation was significant between the multiple defect and the type of defect in the nerve fiber layer (P < 0.002), size of the disc (P < 0.02), and oblique insertion of the disc (P < 0.02), as evaluated by the chisquare test. By multivariate analysis, refractive error was a high-ranking risk factor for multiple defect. Eyes with multiple defects tended to have moderate myopia, a focal nerve fiber layer defect and a small optic disc (category scores 0.0932, 0.0878 and 0.0697) and were less likely to have a diffuse defect in the nerve fiber layer, emmetropia or hyperopia, and a normal disc size (category scores –0.1077, –0.0705, and –0.548). The multiple defect in the retinal nerve fiber in glaucoma was frequently focal and correlated with myopia and a small optic disc.This work was supported by grant-in-aid B-02454403 for scientific research from the Ministry of Education, Science and Culture of Japan Offprint requests to: E. Chihara     

慢性闭角型青光眼未发病眼视网膜神经纤维层的厚度

目的:采用偏振激光扫描仪(GDxVCC系统)检测正常眼、慢性闭角型青光眼(chronicangle-closureglaucoma,CACG)有明显视野缺损的患眼及其视野未受损害的另眼(未发病眼)的视网膜神经纤维层(retinalnervefiberlayer,RNFL)厚度,并进行比较,了解未发病眼RNFL厚度变化有无改变,探讨GDxVCC系统在慢性闭角型青光眼早期诊断中的价值。方法:前瞻性对照研究。慢性闭角型青光眼患者26例,1眼具有可重复性视野缺损,其另眼视野检查正常(如:差异概率图上≤1个测试点在5%概率水平以下),将视野正常的未发病眼定为CACG-视野正常组,有视野缺损的已确诊眼为CACG-视野缺损组;24例48眼年龄相匹配的正常人作为对照组。所有入选对象进行视野和GDxVCC系统检查。采用方差分析,对CACG-视野正常组、CACG-视野缺损组、正常对照组的RNFL参数进行两两比较GDxVCC检测RNFL厚度。结果:与正常对照组相比,CACG患者视野未受损组眼的视网膜神经纤维层变薄。但视野未受损眼的RNFL明显厚于视野缺损眼。3组的各RNFL参数差异均有显著统计学意义;CACG—视野正常组与正常对照组间下方平均值和神经纤维指数(P=0.073,P=0.054)差异无显著统计学意义,但其椭圆平均值、上方平均值及TSNIT标准差与正常对照组相比有极显著统计学意义(P=0.002,P=0.002,P=0.010)。结论:GDxVCC系统可以更早地检测出CACG未发病眼RNFL结构损害,对临床处理早期CACG具有指导意义。     

Study of retinal nerve fibre layer thickness in eyes with high tension glaucoma and hemifield defect

AIM: To quantitatively evaluate retinal nerve fibre layer (RNFL) difference in areas of apparently normal appearing visual field in eyes with high tension glaucoma (HTG) and hemifield defects using scanning laser polarimetry. METHODS: 40 eyes from 40 patients with HTG with superior or inferior hemifield defects based on the Humphrey field analyser (HFA) underwent RNFL thickness measurements. 20 normal eyes from 20 subjects matched in age and refractive error were selected as a control group. The RNFL thickness was measured with a scanning laser polarimeter. Mean RNFL thickness was evaluated in four quadrants (superior, inferior, nasal, and temporal). A superior or inferior quadrant in the defined ring of scanning laser polarimetry corresponds to inferior or superior hemifield in HFA. RESULTS: The mean RNFL thickness in the unaffected quadrant (the quadrant corresponding to the hemifield with apparently normal visual field based on HFA) of the HTG group was significantly thinner than the average RNFL thickness of the corresponding quadrant of the control eyes. The RNFL thickness of the unaffected quadrant in the eyes with HTG was reduced and statistically similar to that of the affected quadrant. Symmetry, calculated as the ratio of superior to inferior RNFL thickness, showed no statistical difference between the study and control group. CONCLUSION: Changes in RNFL are present in the apparently normal hemifield in the eyes with HTG. The thickness of the RNFL is reduced symmetrically in both superior and inferior quadrants based on the GDx parameters.     

Automated static perimetry and nerve fibre layer defects in glaucoma and controls

Correlation of psychophysical tests and structural changes is essential in the management of glaucoma. We compared the mean sensitivity and the short-term fluctuation in eyes with and without defects in the retinal nerve fibre layer in 41 glaucoma patients and 40 controls. In the glaucoma group 87.2% of eyes with visual field defects and 42.3% without visual field defects showed nerve fibre loss. In the control group 36.3% showed nerve fibre loss. In manifest glaucoma the mean sensitivity was 10.9 +/- 7.2 dB in eyes with nerve fibre loss and 19.2 +/- 3.9 dB in eyes without nerve fibre loss. This difference was statistically significant. The corresponding difference in glaucoma suspects and controls was not statistically significant. There was no difference between the short-term fluctuation in the three groups regardless of nerve fibre loss.     

Progression of retinal nerve fibre layer damage in betaxolol- and timolol-treated glaucoma patients

PURPOSE: It has been suggested that there are differences between selective and non-selective beta-blocking agents in their ability to protect glaucomatous eyes. The purpose of this study was to follow glaucoma patients treated with either betaxolol 0.5% or timolol 0.25% ophthalmic solutions and to compare the rate and degree of progression in retinal nerve fibre layer (RNFL) defects between the groups. METHODS: A total of 64 patients were prospectively recruited in a double-masked study and randomly divided into two treatment groups. Retinal nerve fibre layer photographs were analysed. The incidence and total amount of progression in each group were recorded. The rate of impairment was demonstrated using Kaplan Meier survival curves. RESULTS: The analysis included 27 patients treated with betaxolol and 28 patients treated with timolol. Of these, 30% of betaxolol-treated patients and 46% of timolol-treated patients had RNFL damage progression (p = 0.20). The total amount or rate of progression did not differ significantly between the two groups. There was no significant difference in intraocular pressure (IOP) levels between the groups (p = 0.68) during follow-up. The degree of RNFL deterioration did not correlate to the amount of IOP reduction. CONCLUSION: The group treated with betaxolol 0.5% and the group treated with timolol 0.25% did not differ significantly in RNFL damage progression.     

Correlation between optic disc topography and retinal nerve fibre layer measurements in glaucoma

PURPOSE: To test the correlation between optic disc topography (as measured by confocal scanning laser ophthalmoscopy [CSLO]) and retinal nerve fibre layer (RNFL) measurements (as measured by scanning laser polarimetry [SLP]) in glaucoma. MATERIAL AND METHODS: A total of 112 patients with primary open-angle glaucoma and 88 normal individuals were enrolled in the study. All individuals underwent a thorough ophthalmic evaluation, a 24-2 full threshold Humphrey visual field, SLP with the GDx (Version 1.0.12) and CSLO with the TOPSS. Receiver operator characteristic curves were created for each individual CSLO and SLP parameter. Linear correlations between the four best parameters from each device were calculated. Finally, linear correlations between the same variables, controlled for the severity of visual field damage, were calculated. RESULTS: The best individual parameters in the diagnosis of glaucoma for each device were cup area, vertical cup : disc ratio, cup : disc area ratio and average cup depth for CSLO, and the Number, maximum modulation, ellipse modulation and superior nasal for SLP. Moderate to strong correlations were observed in 62% of the pairs. However, only 6% and 12% of the correlations remained moderate when we controlled for the visual field mean deviation and correct pattern standard deviation, respectively. CONCLUSIONS: The correlation between optic disc topography and RNFL measurements in glaucoma patients is moderate and highly dependent on the level of visual field loss.     

Optic disk and retinal nerve fiber layer damage after transient central retinal artery occlusion: an experimental study in rhesus monkeys

PURPOSE: To evaluate the retinal tolerance time to acute ischemic insult in middle-aged or elderly rhesus monkeys with pre-existing atherosclerosis and arterial hypertension. METHODS: In 39 eyes of 39 middle-aged and elderly rhesus monkeys with a mean age of 19.5 +/- 2. 8 years, occlusion of the central retinal artery was produced by temporary clamping of the central retinal artery at its site of entry into the dural sheath of the optic nerve for 97 to 300 minutes. Stereoscopic color fundus photography and fluorescein fundus angiography were performed before central retinal artery occlusion and serially thereafter. Retinal nerve fiber layer damage and optic disk changes were assessed by comparing morphometric evaluation of the color fundus photographs taken before central retinal artery occlusion and color fundus photographs taken at the end of the study. RESULTS: There was a significant correlation between duration of central retinal artery occlusion and decreased visibility of retinal nerve fiber layer (P =.018) and increasing optic disk pallor (P =. 014), and a trend between residual retinal circulation and decreased visibility of retinal nerve fiber layer (P =.085) and optic disk pallor (P =.162). However, there was a marked interindividual variation between the length of central retinal artery occlusion and degree of increased optic disk pallor and decreased visibility of the retinal nerve fiber layer, even among eyes with similar duration of central retinal artery occlusion. Complete or almost total optic nerve atrophy and nerve fiber damage were present in all eyes in which the duration of central retinal artery occlusion was 240 minutes or more. CONCLUSIONS: The findings of this study, compared with our previous study in young healthy rhesus monkeys, indicate that in middle-aged or elderly atherosclerotic and arterial hypertensive rhesus monkeys, central retinal artery occlusion for less than 100 minutes produced no apparent morphometric evidence of optic nerve damage; however, central retinal artery occlusion of 105 minutes but less than 240 minutes produced a variable degree of damage; central retinal artery occlusion for 240 minutes or more produced total or almost total optic nerve atrophy and nerve fiber damage.     

Comparison of localised nerve fibre layer defects in normal tension glaucoma and primary open angle glaucoma

AIM: To compare the pattern of localised nerve fibre layer (NFL) defects in normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). METHODS: 50 NTG eyes and 36 POAG eyes, all with localised NFL defects, were enrolled. On retinal NFL photography, the proximity of the defect to the centre of the fovea (angle alpha) and the sum of the angular width of the defects (angle beta) were determined. Angle alpha was the angle made by a line from the centre of the fovea to the disc centre and a line from the disc centre to the disc margin, where the nearest border of the defect met. The patterns of localised NFL defects in NTG and POAG were compared with angles alpha and beta. Independent t test was used for statistical analysis. RESULTS: Angle alpha in NTG (35.1 (SD 20.0) degrees ) was significantly smaller than that of POAG (45.9 (21.9) degrees ) (p=0.02), while angle beta in NTG (49.0 (31.9) degrees ) was significantly larger than that of POAG (33.1 (23.9) degrees ) (p=0.01). CONCLUSIONS: The pattern of NFL defects in NTG was different from that in POAG. Localised NFL defects in NTG were closer to the fovea and wider in width than those in POAG.     

Influence of experimental chronic high-pressure glaucoma on age-related macular degeneration in rhesus monkeys

PURPOSE: To assess prospectively whether development of age-related macular degeneration is influenced by experimentally induced chronic high-pressure glaucoma, and whether age-related macular degeneration influences the appearance of the optic nerve head in experimental chronic high-pressure glaucoma in older rhesus monkeys. METHODS: The longitudinal study included 102 eyes of 52 rhesus monkeys. The total study group was divided into a group with experimentally induced unilateral chronic high-pressure glaucoma (n = 40 eyes) and a normal control group (n = 62 eyes). Additionally, arterial hypertension and atherosclerosis were experimentally induced in both study groups in a similar percentage of monkeys. Mean monkey age at the end of the study was 19.6 +/- 3.1 years (range, 13-24 years). The macular region, optic disc, and retinal nerve fiber layer were morphometrically evaluated by color wide-angle fundus photographs taken at baseline and at the end of the study. RESULTS: The degree of age-related macular degeneration, measured as number and area of drusen in the foveal and extrafoveal region of the macula, did not differ significantly between the two study groups. In the glaucomatous group, the degree of macular degeneration was statistically independent of the development of parapapillary atrophy, loss of neuroretinal rim, and decrease in the visibility of the retinal nerve fiber layer. CONCLUSIONS: Development of age-related macular degeneration in rhesus monkeys is independent of concomitant chronic high-pressure glaucoma, including the development of glaucomatous parapapillary chorioretinal atrophy. Conversely, age-related macular degeneration does not markedly influence the course of experimental chronic high-pressure glaucoma or the development of parapapillary atrophy in monkeys.     

Rates of retinal nerve fibre layer thickness change in glaucoma patients and control subjects

Purpose

To examine the rates of retinal nerve fibre layer thickness (RNFLT) change in glaucoma patients and healthy, age-similar control subjects with three techniques: scanning laser polarimetry with variable corneal compensation (VCC) and enhanced corneal compensation (ECC), and time-domain optical coherence tomography (OCT).

Methods

Sixty-one patients and thirty-three controls were examined with each technique and with standard automated perimetry (SAP) every 6 months. Rates of global RNFLT change and SAP mean deviation (MD) change were estimated with linear mixed-effects models.

Results

The median (interquartile range) baseline age was 64.4 (58.2, 71.0) years for patients and 62.4 (56.3, 70.1) years for controls (P=0.56). There was a median of seven examinations over 3.1 years for patients and six examinations in 3.0 years for controls. Baseline visual field MD and RNFLT for all imaging modalities were significantly lower (P<0.01) in patients compared with controls. Rates of RNFLT change were not significantly different between patients and controls (P≥0.19). Mean rates of VCC-measured RNFLT change were −0.18 and −0.37 μm per year in patients and controls, whereas the respective figures for ECC and OCT were −0.13 and −0.31 μm per year, and 0.04 and 0.61 μm per year. Mean rates of MD change were −0.20 and 0.03 dB per year in patients and controls, respectively (P=0.01).

Conclusion

Rates of RNFLT change in glaucoma patients were not statistically different from control subjects for any modality. A significantly negative rate of MD change in patients suggests a genuine, continued deterioration in these patients not reflected by RNFLT changes.     

Measurement of retinal nerve fibre layer by scanning laser polarimetry and high pass resolution perimetry in normal tension glaucoma with relatively high or low intraocular pressure

AIMS: To determine whether any differences may exist in the relation between the neural capacity as determined by high pass resolution perimetry and the thickness of the retinal nerve fibre layer (RNFL) in patients having normal tension glaucoma (NTG) with a relatively high intraocular pressure (IOP) between 16 and 21 mm Hg (HNTG) v those with a lower IOP below 15 mm Hg (LNTG). METHODS: Scanning laser polarimetry and high pass resolution perimetry were performed in 20 eyes of 20 patients with HNTG and 21 eyes of 21 patients with LNTG. The correlation between total and regional thickness of the peripapillary RNFL and the corresponding total and regional neural capacity with linear regression analysis were evaluated. RESULTS: Overall, although the total RNFL thickness was not significantly correlated with the total neural capacity, the RNFL thickness in each of the superior and inferior quadrants was significantly correlated with the corresponding regional neural capacity (r = 0.44, p = 0.0045; r = 0.39, p = 0.0126 for each). The RNFL thickness in each of the superior and inferior quadrants in the HNTG group was significantly correlated with the corresponding regional neural capacity (r = 0.52, p = 0.0196; r = 0.49, p = 0.0286 for each). No significant correlation between neural capacity and the RNFL thickness was observed either globally or regionally in the LNTG group. CONCLUSION: The degree of the correlation between neural capacity as determined by high pass resolution perimetry and thickness of the RNFL as measured by scanning laser polarimetry appeared to differ in NTG patients with an IOP higher than 15 mm Hg v those with a lower IOP.     

原发性慢性闭角型青光眼视网膜神经纤维层损害及相关因素研究

目的 观察原发性慢性闭角型青光眼患者(chronic primary angle closure glaucoma,CACG)活体视网膜神经纤维层(retinal nerve fiberlayer thickness,RNFL)损害;分析CACG不同房角粘连程度间RNFL差异及平均RNFL厚度和视野平均缺损(mean visual fielddefects,MD)的相关性.方法 对CACG患者36例(64只眼)和正常人82名(82只眼)用光学相干断层扫描仪(optical coherence tomography,OCT)测量RNFL厚度,比较两者间的差异;比较CACG中无房角粘连、房角粘连范嗣＜1/2和≥1/2圆周眼的RNFL损害的差异;对CACG平均RNFL与相应视野的MD值进行Pearson直线相关分析.结果 CACG平均RNFL(80.61±23.96)μm与正常人(103.7±9.92)μm比较有统计学差异(P＜0.05);CACG平均RNFL厚度在无房角粘连眼(98.46±12.34)μm、粘连范围＜1/2(93.93±14.78)μm和粘连≥1,2圆周眼(69.78±23.82)μm的RNFL的差异有统计学意义(P＜0.05).CACG平均RNFL厚度与视野缺损(MD值)呈正相关(r=0.652,P＜0.001).结论 CACG的RNFL较正常人明显减少;随着CACG病程的发展,平均RNFL厚度减少,视野平均缺损增加.     

Comparative study of retinal nerve fiber layer loss in normal-tension glaucoma and chronic open-angle glaucoma

PURPOSE: To clarify whether loss of the retinal nerve fiber layer in normal-tension glaucoma (NTG) differs from that in chronic open-angle glaucoma (COAG). METHODS: Using a scanning laser polarimeter, retinal nerve fiber layer thickness (RNFLT) was measured in 21 patients with NTG, 21 patients with COAG and 21 normal controls. The three groups were matched for age, and the NTG and COAG groups were matched for visual field loss. RESULTS: The mean RNFLT was significantly less in the NTG than in the control group and less in the COAG than in the controls and NTG group. Although the correlations between the parameters of RNFLT and homotopic visual field measurements were significant in COAG, none of the correlations were significant in NTG. CONCLUSIONS: The present results suggest that loss of the retinal nerve fiber layer in NTG differs from that in COAG.     

Automated detection of wedge-shaped defects in polarimetric images of the retinal nerve fibre layer

PURPOSE: Automated glaucoma detection in images obtained by scanning laser polarimetry is currently insensitive to local abnormalities, impairing its performance. The purpose of this investigation was to test and validate a recently proposed algorithm for detecting wedge-shaped defects. METHODS: In all, 31 eyes of healthy subjects and 37 eyes of glaucoma patients were imaged with a GDx. Each image was classified by two experts in one of four classes, depending on how clear any wedge could be identified. The detection algorithm itself aimed at detecting and combining the edges of the wedge. The performance of both the experts and the algorithm were evaluated. RESULTS: The interobserver correlation, expressed as ICC(3,1), was 0.77. For the clearest cases, the algorithm yielded a sensitivity of 80% at a specificity of 93%, with an area under the ROC of 0.95. Including less obvious cases by the experts resulted in a sensitivity of 55% at a specificity of 95%, with an area under the ROC of 0.89. CONCLUSIONS: It is possible to automatically detect many wedge-shaped defects at a fairly low rate of false-positives. Any detected wedge defect is presented in a user-friendly way, which may assist the clinician in making a diagnosis.     

Localized wedge-shaped defects of retinal nerve fiber layer and disc hemorrhage in glaucoma.

OBJECTIVE: To evaluate frequencies of localized wedge-shaped defects of the retinal nerve fiber layer (RNFL) in eyes with and without disc hemorrhage in normal-tension glaucoma (NTG) and primary open-angle glaucoma (POAG). This study also aims to define a topographic correlation between disc hemorrhage and localized RNFL defects in POAG. DESIGN: Cross-sectional study. PARTICIPANTS AND CONTROLS: The authors studied 83 eyes of 83 patients with NTG (male/female = 23/60; age, 58.8+/-12.9 years) and 20 eyes of 20 patients with POAG (male/female = 9/11; age, 61.6+/-11.4 years); subjects in both groups had developed new disc hemorrhage at the time of enrollment. The authors randomly selected 45 eyes of 45 patients with NTG (male/female = 20/25; age, 62.0+/-9.3 years) and 24 eyes of 24 patients with POAG (male/female = 13/11; age, 56.3+/-14.5 years) with no history of disc hemorrhage during the follow-up period of more than 2 years. METHODS: Visual field in the patients with POAG was matched to that of the patients with NTG regarding global indices for both the hemorrhage and the nonhemorrhage groups. Localized wedge-shaped defects of RNFL were identified by scanning laser ophthalmoscopy using an argon-blue laser. MAIN OUTCOME MEASURES: The frequency of localized RNFL defects and the relationship between the locations of disc hemorrhages and localized RNFL defects were determined. RESULTS: Localized wedge-shaped defects of RNFL occurred significantly more often in the hemorrhage group than in the nonhemorrhage group in both NTG (Fisher's exact probability test, P < 0.0001) and POAG (P < 0.05) patients. Regardless of the presence of disc hemorrhage, there was no significant difference in the frequency of localized RNFL defects between patients with NTG and those with POAG. Most disc hemorrhages were present in the vicinity of the border between localized RNFL defects and relatively healthy-looking RNFL in both patients with POAG and those with NTG. CONCLUSION: Disc hemorrhage is associated with localized damage of RNFL in both NTG and POAG.     

Optic nerve and retinal nerve fiber layer analyzers in glaucoma

There is mounting evidence that retinal nerve fiber layer (RNFL) loss precedes detectable visual field loss in early glaucomatous optic neuropathy. However, examination and photography of the RNFL is a difficult technique in many patients, particularly older individuals, and eyes with small pupils and media opacities. It is subjective, qualitative, variably reproducible, and often unreliable. Furthermore, optic nerve head and RNFL photography is time consuming, operator dependent, has limited sensitivity and specificity, and requires storage space. Imaging technologies have emerged which enable clinicians to perform accurate, objective, and quantitative measurements of the RNFL and optic nerve head topography. There is good agreement between such measurements and clinical estimates of optic nerve head structure and visual function. The reproducibility of these instruments suggests that they have the potential to detect structural change over time. This report will review the technological principles, reproducibility, sensitivity and specificity, capacity to detect glaucomatous progression, and limitations of currently available ocular imaging technologies.