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)     

Glaucomatous damage in normotensive fellow eyes of patients with unilateral hypertensive pseudoexfoliation glaucoma: normotensive pseudoexfoliation glaucoma?

BACKGROUND: The objective of the study was to investigate the prevalence of glaucomatous damage in normotensive fellow eyes of patients with unilateral high-tension pseudoexfoliation (PX) glaucoma. METHODS: Initial examination records of 111 patients with unilateral PX glaucoma with intraocular pressure (IOP) > or = 22 mmHg in the hypertensive eye and IOP < or = 21 mmHg in the normotensive fellow eye without any prior antiglaucomatous treatment were retrospectively studied. Visual field and optic disc examination results were evaluated for glaucomatous damage in the normotensive eyes. RESULTS: Glaucomatous changes were detected in 45 of the 111 fellow eyes (40%). The damage was mild in 25 eyes (22%), moderate in 18 eyes (16%), and severe in 2 (2%). The factors significantly associated with glaucomatous findings in the normotensive eyes were clinical detection of PX, higher age (> or =70 years), higher maximal IOP (> or =18 mmHg) and wider IOP fluctuation (> or =6 mmHg) in the univariate analyses. In the multivariate analysis, associated factors remained as higher maximal IOP (odds ratio = 7.92, confidence interval = 2.82-22.23, P < 0.001) and wider IOP fluctuation (odds ratio = 5.67, confidence interval = 2.05-15.74, P = 0.001). CONCLUSION: Normotensive fellow eyes of patients with unilateral high-tension PX glaucoma are under significant risk of glaucomatous damage, related with the level and the fluctuation range of IOP.     

A comparison of visual field and optic disc appearance depending on the peak intraocular pressure in patients with normal-tension glaucoma

PURPOSE: To investigate the clinical differences between the two groups depending on the peak intraocular pressure(IOP) in patients with normal-tension glaucoma(NTG). METHODS: We studied 96 eyes of 48 NTG patients who were hospitalized for diurnal IOP measurement. Then we selected the eye whose peak IOP was higher than the other, or the right eye if the peak IOP of both eyes was equal. We divided these eyes into a "high-teen" group (peak IOP > or = 16 mmHg) and a "low-teen" group(peak IOP < or = 15 mmHg). We compared these two groups by age, gender, refraction, IOP, visual field defect, optic disc appearance, and tomograph. We used a Humphrey C 30-2 program to estimate the visual field defect and classified the optic disc into four types according to Nicolela's criteria. 22 eyes were imaged with Heidelberg Retina Tomograph (HRT) to obtain topographic parameters of the optic disc. RESULTS: There were no significant differences in age, gender, refraction, optic disc appearance, or tomograph between two groups. The trough and variation range of diurnal IOP were significantly larger in the high-teen group(p < 0.01). The value of mean deviation(MD) given by STATPAC was statistically lower in the high-teen group(p < 0.01). CONCLUSIONS: In patients with NTG, the visual field damage tended to be greater in the high-teen group than in the low-teen group. We surmise that the IOP might influence the progression of visual field defect in NTG.     

Comparison of the Progression of High- and Low-tension Glaucoma as Determined by Two Different Criteria

Purpose

To investigate and compare the progression of medically treated primary open angle glaucoma according to the baseline intraocular pressure (IOP).

Methods

This study included a total of 345 eyes from 345 patients (mean follow-up period, 4.5 years). Eyes were classified into either conventional normal tension glaucoma (cNTG, ≤21 mmHg) or conventional high-tension glaucoma (cHTG, >21 mmHg) groups according to the conventional cut-off value of the IOP. Additionally, the median IOP (15 mmHg) was used to create two other groups (median NTG [mNTG] ≤15 mmHg and median HTG [mHTG] >15 mmHg). Using these values, 306, 39, 153, and 192 eyes were assigned to the cNTG, cHTG, mNTG, and mHTG groups, respectively. Glaucoma progression was determined either by optic disc/retinal nerve fiber layer photographs or serial visual field data.

Results

Mean reduction of IOP after medical treatment and of central corneal thickness was lower in the cNTG group, while the prevalence of disc hemorrhage and baseline visual field mean deviation did not differ between the cNTG and cHTG groups. A mean reduction in the IOP was observed after medical treatment, and central corneal thickness was lower in the mNTG group; disc hemorrhage was more frequent in the mNTG than in the mHTG group. Among the 345 analyzed eyes, 100 (29%) showed progression during the follow-up period. In the cHTG group, a higher baseline IOP (hazard ratio, 1.147; p = 0.024) was associated with glaucoma progression. Disc hemorrhage (hazard ratio, 15.533; p < 0.001) was also strongly associated with progression in the mNTG group.

Conclusions

Baseline IOP was a significant risk factor for glaucoma progression in cHTG patients (10% of our total participants), while disc hemorrhage showed the strongest association with progression in the mNTG group, indicating that a cut-off value other than the conventional 21 mmHg is required to define true low-tension glaucoma in populations where NTG predominates among all glaucoma patients.     

Correlation between intraocular pressure level and optic disc changes in high-tension glaucoma suspects

PURPOSE: To assess the correlation between intraocular pressure (IOP) and future optic disc changes in eyes of patients suspected of having high-tension glaucoma and to determine the target pressure in eyes of patients suspected of having high-tension glaucoma. DESIGN: Prospective, comparative, observational case series. PARTICIPANTS: Fifty-seven eyes of 57 patients suspected of having high-tension glaucoma selected from 226 consecutive patients with glaucoma or suspected glaucoma. INTERVENTION: The status of the optic disc and visual fields was evaluated during an initial examination by confocal laser ophthalmoscopy and automatic perimetry, respectively. Fifty-seven eyes were followed up for at least 2.5 years and then underwent a final examination. IOP was measured every 3 months. MAIN OUTCOME MEASURES: The correlation between changes in optic disc status and IOP control during follow-up was determined. Changes in the optic disc were evaluated by using the percentage change in total contour area, neuroretinal rim area, and cup-to-disc ratio. The control IOPs were evaluated on the basis of the percentage of time during which IOP was <18 mmHg (%<18 mmHg control) and <21 mmHg (%<21 mmHg control) during follow-up in each eye. The correlation between visual field changes and IOP control was also analyzed. RESULTS: Results from 48 (84.2%) of 57 participants were included. Patients were followed up for a mean 4.4 years. The %<21 mmHg control was significantly correlated with changes in neuroretinal rim area (r = 0.40; P = 0.0055) and in cup-to-disc ratio (r = -0.40; P = 0.0051) by linear regression analysis. The correlations were also significant if the difference in the length of follow-up was adjusted by multivariate regression analysis. There was no significant correlation between %<18 mmHg control and changes in disc parameters. Seven (14.6%) of 48 eyes had glaucomatous visual field defects at the final examination. The %<21 mmHg control was significantly lower in eyes with visual field changes compared with eyes with no changes (P = 0.0153; unpaired t test). In contrast, %<18 mmHg control was not significantly different between eyes with and without visual field changes (P = 0.3886). CONCLUSIONS: The IOP level correlates with topographic changes in the optic disc in eyes of patients suspected of having high-tension glaucoma. The target pressure for such eyes may need to be between 18 and 21 mmHg, and <18 mmHg is a safe target level in the treatment of patients suspected of having high-tension glaucoma to delay topographic optic disc changes.     

Effect of topical glaucoma medications on optic disc topography in normal tension glaucoma

PURPOSE: To investigate the effects of topical glaucoma medications on optic disc topography in patients with normal tension glaucoma (NTG) using confocal scanning laser ophthalmoscopy. SUBJECTS AND METHODS: We enrolled 39 NTG patients (39 eyes) who had not been treated for glaucoma. A combined medication of 0.005% latanoprost and 0.5% timolol gel was administered. Optic disc parameters were measured before and after the treatment using the Heidelberg Retina Tomograph (HRT). The treatment period was 20.2 +/- 6.4 days (mean +/- SD). RESULTS: Administration of these two drugs significantly decreased the intraocular pressure (IOP) from 16.7 +/- 1.9 mmHg to 12.3 +/- 1.9 mmHg (26.7 +/- 8.7% decrease). Cup area, cup/disk area ratio and cup volume decreased significantly, while the rim area increased significantly. Linear progression analysis showed a significant correlation between the percent decrease in the IOP and the topographic changes in the cup area, cup/disk area ratio, rim area, cup volume, rim volume, and height variation contour. When the subjects were divided into two groups: patients with high baseline IOP of more than 16 mmHg (HNTG group) and those with low baseline IOP below 15 mmHg (LNTG group), significant changes in several parameters were observed only in the HNTG group. CONCLUSIONS: These results suggest that the topographic changes in the optic disc were induced by the short-term topical glaucoma medications prescribed for the NTG patients, and the changes in several HRT parameters correlated with the percent decrease in the IOP.     

高眼压性和正常眼压性原发性开角型青光眼视神经损害特征的比较

目的探讨高眼压性原发性开角型青光眼(POAG)和正常眼压性青光眼(NTG)患者视神经损害的不同特点。方法应用德国Heidelberg公司生产的视网膜断层扫描仪对高眼压性POAG39例(47只眼)和NTG32例(38只眼)进行定量视盘参数和神经纤维层检查,并行眼底立体照相观察视网膜神经纤维层(RNFL)缺损类型,检测静态定量视野,并对检查结果进行比较。结果(1)NTG组视盘总体参数和分区(除颞侧外)盘沿面积、沿/盘面积小于高眼压性POAG组,而C/D大于高眼压性POAG组;平均RNFL厚度和RNFL面积在颞下和颞上小于高眼压性POAG组;总体盘沿容积小于高眼压性POAG组,总体平均视杯深度和颞下视杯面积大于高眼压性POAG组,两组差异均有统计学意义(P<005)。两组颞侧视盘各参数比较,差异无统计学意义(P>005)。(2)RNFL缺损类型高眼压性POAG组RNFL弥漫性缺损占5319%,局限性缺损占426%;NTG组弥漫性缺损占2105%,局限性缺损占5526%。两组RNFL缺损类型构成比比较,差异有统计学意义(P<001)。结论NTG较高眼压性POAG具有较大的C/D值、C/D面积比和窄盘沿面积,RNFL丢失严重。高眼压性POAG患者的RNFL以弥漫性缺损为主,NTG患者的RNFL以局限性缺损为主。两者视神经损害具有不同特点,其损害机制可能不同。(中华眼科杂志,2005,41136140)     

Sectorization of central 10-deg visual field in open-angle glaucoma

Purpose: To obtain an optimal clustering of the test points of the Humphrey 10-2 program in glaucoma for brief evaluation of the visual field characteristics in the central 10-deg field and to examine its clinical usefulness. Methods: We applied VARCLUS, a new clustering algorithm, to 379 visual fields obtained with the 10-2 program of the Humphey perimeter from 211 eyes of 140 normal-tension glaucoma (NTG) patients and 168 eyes of 111 primary open-angle glaucoma (POAG) patients with the mean deviation (Statpac 2) –15 dB. Based on the interpoint correlation of deviation of the measured threshold value from age-corrected normal reference (total deviation), the 68 2-deg grid points were mathematically clustered, i.e., the central 10-deg visual field was divided into sectors. Between 76 eyes of 76 POAG patients with the peak intraocular pressure (IOP) 25 mmHg (high-tension group) and 85 eyes of 85 NTG patients with the peak IOP 18 mmHg (low-tension group) which had similar mean deviation and age, the mean of total deviation in each obtained sector was compared. Results: The central 10-deg visual field in glaucoma was divided into 10 sectors. The sector pattern obtained was compatible with the projection of nerve fiber layers, with no sectors extending over the horizontal meridian, and it was not completely symmetrical around the horizontal meridian. A group of sectors in the superior arcuate area was significantly more depressed in the low-tension group, while a group of sectors in the inferior centrocecal area was significantly more depressed in the high-tension group. Conclusion: We suggest that the sector pattern obtained here is useful to provide brief evaluation of the result of the 10-2 program and that it may be used in the study of the central visual field in glaucoma.     

Interocular asymmetry of optic disc size and its relevance to visual field loss in normal-tension glaucoma

We evaluated the relevance of interocular asymmetry of optic disc size to the level of intraocular pressure and the extent of optic disc and visual field changes in normal-tension glaucoma (NTG). Fifty-two eyes of 26 patients with NTG were measured for optic disc topography using a computerized image analysis system (IMAGEnet, Topcon), diurnal intraocular pressure (IOP), and Octopus automated visual field. Of the 26 patients, 22 had interocular asymmetry of the optic disc area of at least 0.01 mm² and of mean IOP of at least 0.3 mmHg. Of these 22 patients, 8 had the higher mean IOP in the eye with the larger optic disc. In these 8 patients, the visual field defect was significantly more advanced in the eye with the larger optic disc (Wilcoxon signed ranks test, P < 0.05). These findings appear to support the hypothesis that an eye with a large optic disc may be more vulnerable to a rise in IOP.     

Risk factors for progression of normal‐tension glaucoma under β‐blocker monotherapy

Purpose: To prospectively study prognostic factors for normal‐tension glaucoma (NTG) under treatment with topical β‐blocker. Methods: One hundred and forty‐six eyes of 146 patients with NTG with a mean untreated intraocular pressure (IOP) of 14 mmHg, mild to moderate visual field damage and mean spherical equivalent refraction of ?3.5 (?8.0 to +2.0) dioptre were randomized to topical nipradilol or timolol and followed for 3 years. The Humphrey full threshold 30‐2 visual field test was performed every 6 months, and optic disc photographs were obtained every 12 months. Progression was defined as visual field progression, optic disc and/or peripapillary nerve fibre layer change, and factors relating to progression were evaluated using Cox proportional hazards models. Results: IOP decreased by 1.0 mmHg over the 3‐year period, during which 35% showed progression according to the aforementioned criteria. Optic disc haemorrhage (hazard ratio [HR] 4.00, p < 0.001) and less extent of myopia (per dioptre, HR 1.15, p = 0.013) were significant risk factors. When progression was defined by visual field progression only, less extent of myopia was again a significant risk factor (HR 1.17, p = 0.038). Conclusion: Beside optic disc haemorrhage, less extent of myopia was a risk factor for progression in the current NTG population where most patients were mildly myopic and IOP during follow‐up averaged 13.2 mmHg under topical β‐blocker.     

Screening for glaucoma in a general population with the non-mydriatic fundus camera and the frequency doubling perimeter

PURPOSE: To evaluate the usefulness of non-mydriatic fundus camera (NMFu-camera) and frequency doubling perimeter (FDP) for detecting glaucoma in a general population. METHODS: This prospective observational multicenter study consisted in screening for glaucoma in the populations of three Belgian cities. Intraocular pressure (IOP) was measured with non-contact pneumo-tonometer (NCT) and applanation tonometry (AT) if NCT IOP was > or = 17 mmHg. Visual field was screened with FDP (C-20-5) and digitized optic disc photographs (ODPs) were taken with NMFu-camera. FDP was considered abnormal if at least one defective point was found. ODPs were graded as normal or glaucomatous by consensus of three glaucoma specialists. Optic disc and visual field results were matched per eye. Subjects with known ocular hypertension and/or treated primary open angle glaucoma were excluded from the analysis. RESULTS: A total of 1620 subjects were included in the study. Their mean age was 63.2 years. AT IOP was > 21 mmHg in 8.2%. A total of 98.1% of ODPs could be interpreted. Glaucomatous optic discs were detected in 3.5% of the subjects. In this group only 24% had an AT IOP > or = 22 mmHg. FDP was abnormal in 44.5%. The sensitivity and specificity of FDP to identify patients with an optic disc graded as glaucomatous were 58.6% and 64.3% respectively. CONCLUSIONS: The combined use of the NMFu-camera and the FDP is a feasible method for an initial glaucoma mass screening. NMFu-camera may be a useful and quick method to screen for glaucomatous damage in a community. FDP in screening strategy was revealed to be not sensitive enough when setting the cut-off value at one defective test location. IOP measurements were confirmed to be a poor tool to detect glaucomatous damage.     

Diffuse nerve fiber layer loss in normal tension glaucoma

14 eyes of 14 normal tension glaucoma (NTG) patients with the maximum intraocular pressure (IOP) 19 mmHg and 16 eyes of 16 NTG patients with the maximum IOP<19 mmHg were examined. All patients had a scotoma confined to the upper or lower hemifield. Eyes with the maximum IOP a 19 mmHg showed significantly diffuse retinal nerve fiber layer (RNFL) loss in the RNFL area corresponded to the spared visual hemifield as compared to those with the maximum IOP<19 mmHg. The result suggests that, even in NTG, IOP may be an important factor causing optic nerve damage.Abbreviations NTG Normal Tension Glaucoma     

Risk factors for progression of normal-tension glaucoma under β-blocker monotherapy

Purpose: To prospectively study prognostic factors for normal-tension glaucoma (NTG) under treatment with topical β-blocker. Methods: One hundred and forty-six eyes of 146 patients with NTG with a mean untreated intraocular pressure (IOP) of 14?mmHg, mild to moderate visual field damage and mean spherical equivalent refraction of -3.5 (-8.0 to +2.0) dioptre were randomized to topical nipradilol or timolol and followed for 3?years. The Humphrey full threshold 30-2 visual field test was performed every 6?months, and optic disc photographs were obtained every 12?months. Progression was defined as visual field progression, optic disc and/or peripapillary nerve fibre layer change, and factors relating to progression were evaluated using Cox proportional hazards models. Results: IOP decreased by 1.0?mmHg over the 3-year period, during which 35% showed progression according to the aforementioned criteria. Optic disc haemorrhage (hazard ratio [HR] 4.00, p?相似文献   

Intraocular pressure reduction with topical medications and progression of normal‐tension glaucoma: a 12‐year mean follow‐up study

Purpose: To investigate whether the amount of intraocular pressure (IOP) reduction with topical medications is associated with the progression of normal‐tension glaucoma (NTG) and to identify risk factors for NTG progression. Methods: The medical records of 121 eyes of 121 NTG patients, who were treated with topical medications for more than 7 years, were reviewed. NTG progression was defined by either structural (optic disc or retinal nerve fibre layer) or functional (visual field) deterioration. Patients were divided into tertile groups according to the percentage IOP reduction from baseline, and the cumulative probability of NTG progression between upper and lower tertile group was compared using Kaplan–Meier survival analysis. Multivariate analysis with Cox’s proportional hazard model was performed to identify the hazard ratio (HR) of clinical factors for NTG progression. Results: The average follow‐up period was 12.2 years, and 56 of 121 eyes (46.3%) showed the NTG progression. Kaplan–Meier analysis revealed that upper tertile group (percentage IOP reduction >22.1%) showed a greater cumulative probability of non‐progression than lower tertile group (percentage IOP reduction < 13.3%; p = 0.012). Multivariate Cox’s proportional hazard model indicated that percentage reduction of IOP (HR = 0.964; p = 0.007) and the occurrence of disc haemorrhage (HR = 2.410; p = 0.008) were significantly associated with NTG progression. Conclusions: The amount of IOP reduction using topical medications was related to NTG progression, and lower percentage reduction in IOP was a consistent risk factor for progression.     

Comparison of visual field defects in the low-tension glaucomas with those in the high-tension glaucomas

We compared the visual fields of 79 eyes (48 patients) with low-tension glaucoma (intraocular pressure less than 21 mm Hg) to the visual fields of 106 eyes (74 patients) with high-tension glaucoma (intraocular pressure greater than 30 mm Hg). Both groups had similar amounts of total field loss as determined by computerized threshold perimetry. Scotomas in the low-tension group had a steeper slope (P less than .001), were significantly closer to fixation (P less than .001), and had greater depth (P less than .001) than those in the high-tension group. These findings suggested that more than one causative factor is important in the production of optic nerve damage in glaucoma.     

Myopia and advanced-stage open-angle glaucoma

OBJECTIVE: To investigate the effect of myopic refraction on the central visual field in patients with advanced open-angle glaucoma (OAG). DESIGN: Multicenter cross-sectional study. PARTICIPANTS: Three hundred thirteen OAG eyes (176 eyes of 176 primary open-angle glaucoma [POAG] patients and 137 eyes of 137 normal-tension glaucoma [NTG] patients) with clear ocular media and a mean deviation (MD) <-15 dB. Patients with a recorded maximum intraocular pressure (IOP) of 22 mmHg or greater were classified as POAG, and those with an IOP of 21 mmHg or less were classified as NTG. METHODS: Multiple regression analysis was used to study the influence of refraction on 12 central test points of the C30-2 Humphrey program, and the differences in visual field defects between POAG and NTG eyes were examined using logistic discriminant analysis. In the multiple regression analysis, total deviation (TD) of the 12 test points was graded and used as the dependent variable, and MD and the spherical equivalent refraction were the explanatory variables. In the logistic discrimination analysis, TD, MD, and refraction were covariants that determined the OAG subtypes. MAIN OUTCOME MEASURES: TD values of the 12 central test points (C30-2 program). RESULTS: Higher myopic refraction was significantly associated with more damage at a point just temporal and inferior to the fixation point in POAG eyes, whereas it was significantly associated with less damage at test points just temporal and superior to the fixation point in NTG eyes. After correcting for the influence of refraction, POAG eyes had significantly more damage at a test point just temporal and inferior to the fixation point, whereas NTG eyes had significantly more damage at those test points nasal and inferior to the fixation point. CONCLUSIONS: High myopia constitutes a threat to the remaining lower cecocentral visual field and is one of the factors that interfere with the quality of vision in advanced OAG with high IOP but not low IOP.     

Central corneal thickness in low-tension glaucoma

BACKGROUND: It is possible that the intraocular pressure (IOP) is underestimated in eyes whose central cornea is thinner than normal. The objective of this study was to determine and establish the significance of central corneal thickness in patients with low-tension (normal-tension) glaucoma compared with those with chronic open-angle glaucoma (COAG) or ocular hypertension and healthy eyes. METHODS: The study was carried out from February 1998 to May 1999. Central corneal thickness was measured by ultrasonic pachymetry and IOP was measured by Goldmann applanation tonometry in 25 patients with low-tension glaucoma (untreated IOP less than 21 mm Hg with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 80 patients with COAG (untreated IOP 21 mm Hg or greater with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 16 patients with ocular hypertension (untreated IOP 21 mm Hg or greater, with normal optic nerve head and no history of glaucoma or elevated IOP, and normal visual field on automated perimetry) and 50 control subjects (untreated IOP less than 21 mm Hg with normal optic nerve head and no history of glaucoma or elevated IOP). Analysis with Pearson's product-moment correlation was performed to determine the correlation of IOP and central corneal thickness, and one-way analysis of variance was used to compare corneal thickness between groups. RESULTS: The central cornea was significantly thinner in the low-tension glaucoma group (mean 513.2 mu [standard deviation (SD) 26.1 mu]) than in the COAG group (mean 548.2 mu [SD 35.0 mu]) and the control group (mean 556.7 mu [SD 35.9 mu]) (p < 0.001). No significant difference in corneal thickness was found between the COAG and control groups. The ocular hypertension group had significantly thicker corneas (mean 597.5 mu [SD 23.6 mu]) than the three other groups (p < 0.001). INTERPRETATION: Patients with low-tension glaucoma may have thinner corneas than patients with COAG and healthy subjects. This results in underestimation of their IOP. Corneal thickness should be taken into account when managing these patients to avoid undertreatment.     

Comparison of localized retinal nerve fiber layer defects between a low-teen intraocular pressure group and a high-teen intraocular pressure group in normal-tension glaucoma patients

PURPOSE: To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients. METHODS: Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of 15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups. RESULTS: Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07). CONCLUSIONS: Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.     

The amount of intraocular pressure rise during pharmacological pupillary dilatation is an indicator of the likelihood of future progression of glaucoma

AIM: To determine if there is a relationship between the amount of increase in IOP following dilatation with a cycloplegic agent and the future course of glaucoma. METHOD: A retrospective chart review of 100 eyes from 55 subjects with open-angle glaucoma who had had IOP measured before and after pharmacological pupillary dilatation was performed to establish the rate of progression of glaucoma, based on serial evaluation of the visual fields using the glaucoma staging system 2 (GSS 2), and optic discs using the disc damage likelihood scale (DDLS). Progressive visual field loss was defined as an increase of two or more stages with the GSS 2 and progressive deterioration of the disc was defined as an increase of two or more stages with the DDLS. Mean follow-up time was 7.2 years. RESULTS: A total of 26 eyes showed glaucomatous progression. The likelihood of progression of glaucoma was related to the amount of IOP increase after pharmacological pupillary dilatation. For every 1 mmHg increase in IOP, the odds of progression increased 24% (p = 0.008). The likelihood of progression of glaucoma, however, was not related to the baseline IOP, which was 20.63 mmHg (SD = 4.59 mmHg) in those showing deterioration of disc or field and 19.72 mmHg (SD = 5.32 mmHg) in those not worsening according to our definition. CONCLUSION: In patients with open-angle glaucoma, the amount of increase in IOP caused by pharmacological pupillary dilatation is related to the likelihood of future progression of glaucoma.     

Intravascular oxygen saturation in retinal vessels in normal subjects and open-angle glaucoma subjects

PURPOSE: To measure the oxygen saturation (SO(2)) in retinal arterioles and venules in patients with glaucomatous optic neuropathy. METHODS: We examined SO(2) in retinal arterioles and venules simultaneously by imaging spectrometry. Oxygen saturation was evaluated according to the difference of the extinction spectra of haemoglobin and oxyhaemoglobin. The arterio-venous difference (avD) was calculated by (SO(2art) - SO(2ven)). The optic nerve head topography was estimated by Heidelberg retinal tomography and the visual field using the Octopus G1. We examined one eye in each of 58 healthy persons (mean age 58.6 +/- 10.7 years; mean rim area 1.52 +/- 0.33 mm(2); mean defect 0.65 +/- 1.31 dB; mean intraocular pressure [IOP] 18.5 +/- 2.7 mmHg), 49 patients with normal-tension primary open-angle glaucoma (NTG) (mean age 63.0 +/- 8.5 years; mean rim area 0.89 +/- 0.34 mm(2); mean defect 5.4 +/- 4.1 dB; mean IOP 19.2 +/- 2.9 mmHg), and 45 patients with high-tension primary open-angle glaucoma (POAG) (mean age 62.6 +/- 10.3 years; mean rim area 0.97 +/- 0.47 mm(2); mean defect 7.1 +/- 6.4 dB; mean IOP 31.6 +/- 10.8 mmHg). RESULTS: The intraclass correlation coefficients of the SO(2) measurement were 0.82 (arteriole) and 0.59 (venule). In normal eyes, the SO(2art), SO(2ven) and avD were 92.3 +/- 3.4%, 55.7 +/- 6.8% and 36.6 +/- 7.0%, respectively. Equivalent data were 89.7 +/- 5.4%, 56.0 +/- 8.3% and 33.7 +/- 10.6%, respectively, in NTG eyes and 91.4 +/- 4.0%, 58.3 +/- 10.5% and 33.1 +/- 11.5%, respectively, in POAG eyes. Over all examined eyes, the arteriolar SO(2) and the retinal arterio-venous difference correlated significantly with the rim area. CONCLUSION: Eyes with NTG showed significantly decreased arteriolar SO(2). These changes were not seen in POAG patients.