Central corneal thickness and progression of the visual field and optic disc in glaucoma

AIMS: To determine whether central corneal thickness (CCT) is a significant predictor of visual field and optic disc progression in open angle glaucoma. METHODS: Data were obtained from a prospective study of glaucoma patients tested with static automated perimetry and confocal scanning laser tomography every 6 months. Progression was determined using a trend based approach called evidence of change (EOC) analysis in which sectoral ordinal scores based on the significance of regression coefficients of visual field pattern deviation and neuroretinal rim area over time are summed. Visual field progression was also determined using the event based glaucoma change probability (GCP) analysis using both total and pattern deviation. RESULTS: The sample contained 101 eyes of 54 patients (mean (SD) age 56.5 (9.8) years) with a mean follow up of 9.2 (0.7) years and 20.7 (2.3) sets of examinations every 6 months. Lower CCT was associated with worse baseline visual fields and lower mean IOP in the follow up. In the longitudinal analysis CCT was not correlated with the EOC scores for visual field or optic disc change. In the GCP analyses, there was a tendency for groups classified as progressing to have lower CCT compared to non-progressing groups. In a multivariate analyses accounting for IOP, the opposite was found, whereby higher CCT was associated with visual field progression. None of the independent factors were predictive of optic disc progression. CONCLUSIONS: In this cohort of patients with established glaucoma, CCT was not a useful index in the risk assessment of visual field and optic disc progression.     

Multifocal VEP and OCT findings in patients with primary open angle glaucoma: A cross-sectional study

ABSTRACT: Bakground To evaluate objectively the anatomical and functional changes of optic nerve in eyes with primary open angle glaucoma (POAG) by the joint use of optical coherence tomography (OCT) and multifocal visual evoked potentials (mfVEP). METHODS: 29 eyes with open angle glaucoma and visual field defects, as well as 20 eyes of 10 age-matched control normal subjects were tested. All participants underwent a complete ophthalmological examination. Moreover, Humphrey visual field test, OCT examination and recording of mfVEP were performed. Amplitude and implicit time of mfVEP, as well as RNFL thickness were measured. Differences in density components of mfVEP and in RNFL thickness among POAG eyes and control eyes were examined using Student's t-test. RESULTS: In glaucomatous eyes the mean Retinal Response Density (RRD) was lower than normal in ring 1, 2 and 3 of mfVEP (p < 0.0001). Specifically the mean amplitude of mfVEP in POAG eyes was estimated at 34.2 +/- 17.6 nV/deg2, 6.9 +/- 4.8 nV/deg2 and 2.6 +/- 1.6 nV/deg2 in rings 1, 2 and 3 respectively. In contrast the mean implicit time was similar to control eyes. In addition, the mean RNFL thickness in POAG eyes was estimated at 76.8 +/- 26.6 mum in the superior area, 52.1 +/- 16.3 mum in the temporal area, 75.9 +/- 32.5 mum in the inferior area and 58.6 +/- 19.4 mum in the nasal area. There was a statistically significant difference in RNFL thickness in all peripapillary areas (p < 0.0001) between POAG eyes and controls, with superior and inferior area to present the highest decrease. CONCLUSIONS: Our study shows that, although Standard Automatic Perimetry is the gold standard to evaluate glaucomatous neuropathy, the joint use of mfVEP and OCT could be useful in better monitoring glaucoma progression.     

Relationship of change in central corneal thickness to visual field progression in eyes with glaucoma

Background

To assess the relationship between baseline central corneal thickness (CCT) and/or ongoing CCT change over time with subsequent visual field progression.

Methods

One hundred sixty three eyes of 163 patients with medically treated glaucoma were followed up for 6.8?±?1.8 years. Exclusion criteria was laser or intraocular surgery. Baseline and follow up CCT, confocal scanning laser tomography and visual fields were performed. CCT and CCT change related to visual field progression using Glaucoma Progress Analysis were assessed. Multivariate logistic regression analysis for predictive factors of glaucoma progression was used to analyze data.

Results

Thinner baseline CCT was associated with more advanced damage at presentation, mean deviation (MD) (r?=?0.17, p?=?0.02) and neuroretinal rim area (NRR) (r?=?0.20, p?=?0.02). Progressing eyes had significantly thinner (p?=?0.01) baseline CCT compared to non-progressing eyes. The slope of visual field change was significantly greater (p?=?0.05) for thinner (<540 μm) as compared to thicker eyes. A small but significant CCT reduction (12.78?±?13.35 μm, p?<?0.0001) was noted in all eyes; however, there was no significant difference (p?=?0.95) in the amount of change between progressing and non-progressing eyes. CCT change did not correlate with MD or NRR change. A thinner CCT (Odds ratio?=?1.80, p?=?0.02), but not CCT change (Odds ratio?=?1.07, p?=?0.69), was a significant risk factor for glaucoma progression.

Conclusions

CCT correlates significantly with the amount of glaucomatous damage at presentation. Thinner corneas may be associated with increased risk of visual field progression. CCT reduced slightly over time in eyes with glaucoma; but the magnitude of this change was not related to visual field progression.     

Twenty-year follow-up of visual field defects in primary glaucoma eyes

PURPOSE: The time course of visual field defects in patients with primary glaucoma was investigated for 20 or more years. METHODS: The subjects were 51 eyes of 29 patients (open angle glaucoma, 40 eyes of 21 patients angle closure glaucoma, 11 eyes of 8 patients). The mean intraocular pressure of these subjects was within 21 mmHg during the follow-up periods. All the eyes were monitored with Goldmann's perimetry, and the visual field was graded using Kozaki's classification. RESULTS: At the 20-year follow-up, 68% of the open angle cases and 45% of the angle closure cases had significant progression of visual field defects. There was no significant difference in average intraocular pressure during the follow-up period between the progression group and the stable group. CONCLUSION: These results suggested that, in a follow-up of twenty years, visual field defects both in primary open angle glaucoma and chronic angle closure glaucoma can progress frequently, even if the intraocular pressure of these patients was well controlled.     

Central corneal thickness in children: stability over time

PURPOSE: To evaluate central corneal thickness (CCT) in children over time. DESIGN: Prospective observational case series. METHODS: CCT was measured by ultrasonic pachymetry in 69 eyes of 38 subjects age 3 to 14 years recruited from the Duke University Eye Center. Subjects included patients with and without glaucoma. RESULTS: For eyes on no glaucoma medication, the mean change in CCT was -1.9 +/- 14 microm (n = 30; mean time between CCT measurements, 567 days). For eyes on stable glaucoma medication, the mean change in CCT was +8.1 +/- 26 microm (n = 27; mean time between CCT measurements, 580 days). For eyes with a change in medical therapy between visits, the mean change in CCT was -3.8 +/- 24 microm (n = 8, mean number of days between visits 723). Four eyes underwent trabeculectomy between measurements and experienced a mean change in CCT of -9.0 +/- 6 microm with a mean of 1257 days between measurements. These CCT changes were not statistically significant. CONCLUSIONS: CCT of children ages 3 to 14 years appears stable over a one- to two-year interval.     

Relationship between central corneal thickness and localized retinal nerve fiber layer defect in normal-tension glaucoma

PURPOSE: To determine whether central corneal thickness (CCT) is related to the extent of localized retinal nerve fiber layer (RNFL) defect at the initial examination of normal-tension glaucoma (NTG) patients. PATIENTS AND METHODS: Seventy-five eyes of 75 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual field defects at the initial visit to a glaucoma specialist were selected for this study. All participants completed refraction, Goldmann applanation tonometry, CCT measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. Each patient's age, spherical equivalent, intraocular pressure, CCT, approximation of the RNFL defect to the fovea (angle alpha), circumferential width of the RNFL defects (angle beta), horizontal and vertical cup-to-disc ratios, and mean deviation of visual field were analyzed. RESULTS: In univariate and multivariate analyses, lower CCT was significantly associated with increased horizontal and vertical cup-to-disc ratios, decreased angle alpha, and increased angle beta. For a decrease of 10 microm of CCT, horizontal and vertical cup-to-disc ratios increased by 0.020, angle alpha decreased by 1.58 degrees, and angle beta increased by 1.71 degrees, respectively. CONCLUSION: CCT is a significant factor in predicting the extent of localized RNFL defect at the initial examination of NTG patients.     

Role of central corneal thickness on baseline parameters and progression of visual fields in open angle glaucoma

PURPOSE: To evaluate the relationship of central corneal thickness (CCT) to baseline visual field parameters and visual field progression in patients with primary open-angle glaucoma (POAG). METHODS: Charts of consecutive patients with POAG were reviewed to obtain visual field data. Visual field was measured by standard threshold static perimetry. Variables analyzed included mean deviation (MD) and pattern standard deviation (PSD). RESULTS: A total of 121 eyes examined over 4 years were evaluated. A significant negative relationship between CCT and PSD (correlation coefficient: -0.02, p<0.05) was found. Analyses comparing CCT to change in PSD and MD (visual field progression) were statistically not significant. CONCLUSIONS: Patients with thinner corneas initially present with a greater visual field defect, indicating that thin corneas may contribute to advanced glaucomatous damage at the time of diagnosis. However, CCT does not seem to be a significant risk factor for progression of the disease.     

Visual field progression outcomes in glaucoma subtypes

Purpose: To determine whether glaucoma subtype is an independent risk factor for visual field (VF) progression. Methods: We reviewed the charts of glaucoma suspects and glaucoma patients seen in a referral practice between 1999 and 2009. Automated pointwise linear regression analysis determined the rates of VF change. A progression endpoint was determined when two or more adjacent test locations in the same hemifield showed a threshold sensitivity decline at a rate of ≥1.0 dB/year with p < 0.01. Results: We included 841 eyes (841 patients; mean age, 64.1 ± 12.6 years; mean number of VF tests, 10.8 ± 2.8; mean follow‐up, 6.4 ± 1.7 years). The glaucomatous group consisted of angle‐closure glaucoma (76 eyes), juvenile primary open‐angle glaucoma (37 eyes), normal‐tension glaucoma (81 eyes), pigmentary glaucoma (34 eyes), primary open‐angle glaucoma (275 eyes) and exfoliative glaucoma (XFG, 84 eyes). Normal‐tension glaucoma eyes were more likely to present with beta‐zone parapapillary atrophy and disc haemorrhage (p < 0.01). Exfoliative glaucoma eyes had the fastest rates of global VF change (?0.65 dB/year), as well as the highest mean, fluctuation, and peak intraocular pressure during follow‐up (16.5, 3.0 and 22.0 mmHg, respectively) and reached a progression endpoint more frequently (40%). After adjusting for all covariates, including the glaucoma phenotype, there was no difference among groups regarding global rates of VF change and the risk of reaching a progression endpoint. Conclusions: Despite different clinical features, epidemiology and genetics, glaucoma phenotype is not an independent risk factor for VF progression. Rather, variations in well‐known, reported risk factors remain important disease parameters that affect progression.     

Relationship between central corneal thickness and progression of visual field loss in patients with open-angle glaucoma

ObjectiveTo determine whether a relationship exists between central corneal thickness (CCT) and visual field (VF) progression in treated patients with open-angle glaucoma and asymmetric corneal thickness.DesignRetrospective chart review.ParticipantsWe studied 100 charts of patients with open-angle glaucoma and also bilateral CCT and VF data.MethodsCharts from 2 glaucoma subspecialty practices were reviewed. The CCT and the rate of progression and event analysis of visual field data were assessed in all subjects. Subanalysis was performed for subjects whose CCT asymmetry was ≥ 16 μm.ResultsThe mean CCT was 544 ± 40 μm OD and 541 ± 40 μm OS. The mean CCT difference between fellow eyes was 15 ± 11 μm (range, 1 to 52 μm). There was no significant intrasubject difference in the mean deviation (MD) and the pattern standard deviation (PSD) (p =0.917 and p = 0.704, respectively; paired t test). The more advanced VF MDs and PSDs were found in the thin eyes of 47 and 50 subjects, respectively (p = 0.459 and p = 0.317, respectively; χ²). Of the 65 subjects whose visual field indexes were available, 34 had the more rapid visual field index rates of progression in the thin eye (p = 0.400; χ²). Of the 27 subjects for whom event analysis was available, 15 had the worse progression category in the thin eye (p = 0.453, χ2). Subgroup analysis of 48 subjects with ≥ 16 μm CCT asymmetry did not find any significant difference in analyses of field progression between fellow eyes.ConclusionsNo relationship was found between CCT and VF loss in treated patients with primary open-angle glaucoma or normal-tension glaucoma with asymmetrical CCT. Specifically, the thin eye did not have the more advanced VF loss or more rapid VF progression.     

角膜中央厚度与原发性开角型青光眼视网膜神经纤维层厚度的关系

目的:研究原发性开角型青光眼患者的角膜中央厚度(central corneal thickness,CCT)与开角型青光眼严重程度之间的关系。方法:对眼科门诊原发性开角型青光眼患者30例60眼分别进行视野,OCT检查中央角膜厚度及视神经纤维层厚度,并进行统计学分析。结果:研究组中开角型青光眼患者的平均中央角膜厚度为561.8±44.9(483～609)μm。根据同一患者双侧中央角膜厚度分组,组间视野平均缺损(MD),平均视神经层厚度(average retinal nerve fiber layer,Average RNFL)有显著性差异(P=0.034,P=0.012),CCT较薄组MD值及平均视神经层厚度均较低。CCT与MD,平均视网膜神经纤维层厚度正相关(P=0.043,P=0.006)。结论:中央角膜厚度与开角型青光眼视神经损伤有一定相关性。     

术后眼压正常的原发性开角型青光眼中央角膜厚度与视神经受损关系

目的 探讨手术后眼压达正常的原发性开角型青光眼(primary open angle glaucoma,POAG)患者中央角膜厚度(Central Corneal Thickness,CCT)与视野、视神经损害进展的关系.方法 对127例施行小梁切除术的原发性开角型青光眼患者进行角膜测厚、视野检查及海德堡视网膜断层扫描(HRT-2).根据CCT将127例患者分成两组:第一组CCT<540μm(n=59),第二组CCT≥540μm(n=68).手术后1个月开始检查,随访2年,对所得数据进行分析.结果 两组术后2年除了视盘面积(DA)无差异外,其平均视野缺损值(MD)、视杯面积(CA)、最大视杯深度(MxCD)、杯盘面积比(C/DAR)、盘沿面积(RA)、视杯形态测量(CSM)、平均视网膜神经纤维厚度(mRNFLT)与首诊比较差异均有统计学意义(P<0.05),且第一组上述指标的进展均较第二组加快(P<0.05).结论 原发性开角型青光眼患者即使手术后眼压控制正常,其视野及视神经仍出现继续损害,角膜厚度薄者视野及视神经的损害更明显.     

Update on prospective glaucoma intervention studies

BACKGROUND: Previously published prospective therapeutic intervention studies in ocular hypertension and glaucoma are summarized. MATERIAL AND METHODS: The concept of intraocular pressure reduction was evaluated in normal tension glaucoma ["Early manifest glaucoma trial (EMGT)"], the "Collaborative normal-tension glaucoma study (CNTGS)" and ocular hypertension ["Ocular hypertensive study (OHTS)" as well as the "European glaucoma prevention study (EGPS)"]. Early open angle glaucoma patients were included in the EMGT trial as well as the "Collaborative initial glaucoma treatment study (CIGTS)", whereas advanced glaucoma patients were examined in the "Advanced glaucoma intervention study (AGIS)". RESULTS: The study design, the results and the conclusions will be highlighted in the text. CONCLUSIONS: The therapeutic concept of intraocular pressure reduction decreases the risk of progression by 50 % in normal tension glaucoma, ocular hypertension and early open angle glaucoma. The mean pressure reduction to 12 mmHg in advanced glaucoma abolished visual field progression. The natural course of the disease documented by the control groups is now known. Sensitive glaucoma progression detection is clinically available by glaucoma change probability maps (Humphrey-full threshold perimetry) used in the EMGT.     

Rates of visual field progression in clinical glaucoma care

Purpose: To investigate rates of visual field progression and factors associated with progression rate in open‐angle glaucoma in clinical glaucoma care. Methods: We performed a retrospective chart review of all patients with manifest primary open‐angle glaucoma (POAG) and pseudoexfoliation glaucoma (PEXG) followed ≥ 5 years with ≥5 SITA Standard fields. Exclusion criteria were minimal. Demographics, intraocular pressure values (IOP), treatment and treatment changes, and visual field (VF) data were recorded. VF progression rates were calculated as slopes of mean deviation (MD) over time. Results: Five hundred and eighty‐three patients were eligible. Three hundred and sixty‐seven (62%) had POAG and 221 (38%) PEXG. Median MD at study start was ?10.0 dB. Mean follow‐up time was 7.8 years (SD ± 1.2); mean number of VF tests was 8.9 (SD ± 2.8). Progression rates varied very much among patients with a mean of ?0.80 dB/year (SD ± 0.82; median rate, ?0.62), and 5.6% of patients progressed at rates worse than ?2.5 dB per year A negative slope of MD values was observed in 89% of patients. Mean IOP of all visits decreased over the study period from 20.15 to 18.10 mmHg. Higher age and mean IOP, and more intensive treatment were associated with more rapid progression, while PEXG and IOP variation were not, if treatment intensity was taken into account. Conclusion: Rates of visual field progression in manifest glaucoma with field loss in ordinary clinical care were highly variable. Progression rates rapid enough to influence quality of life were common.     

高度近视合并青光眼患者黄斑区脉络膜厚度的多元回归分析

目的：探讨高度近视合并原发性开角型青光眼（ POAG ）患者的黄斑区脉络膜厚度分布特征及影响黄斑区脉络膜厚度的相关因素。方法：研究共纳入高度近视合并POAG患者18例32眼, POAG患者20例36眼,以及高度近视患者21例33眼。采用频域OCT增强深度扫描测定中心凹下（ SFCT ）、距中心凹1 mm和3 mm处上、下、鼻、颞四个方位的脉络膜厚度（S1CT、S3CT、I1CT、I3CT、N1CT、N3CT、T1CT、T3CT）。比较三组间黄斑区脉络膜厚度的差异,并利用多元回归分析对POAG患者的诊断、屈光度、年龄、眼压、角膜厚度、视野缺损等对黄斑区脉络膜厚度的影响进行分析。结果：高度近视合并POAG患者的黄斑区脉络膜厚度较POAG患者在各测量位置均明显变薄（均P＜0．05）,但与高度近视患者在各测量点的脉络膜厚度差异均无统计学意义（均P＞0．05）。屈光度是POAG患者黄斑区各测量点脉络膜厚度的主要影响因素,颞侧距中心凹3 mm处的脉络膜厚度（ S3 CT ）受年龄的影响,而诊断、视野缺损、眼压及角膜厚度不是脉络膜厚度的影响因素。结论：高度近视合并POAG患者黄斑区脉络膜厚度比单纯POAG患者薄,但与高度近视患者无统计学差异,黄斑区脉络膜厚度与青光眼性视神经损伤程度无明显关联。     

Disc and field damage in patients with unilateral visual field loss from primary open-angle glaucoma

To assess the temporal relationship between field and disc change in early glaucoma, 24 patients with unilateral visual field loss from primary open angle glaucoma were identified for planimetric optic disc measurements. Cross-sectional analysis of disc rim area was performed and compared to 25 age-matched normal controls. The mean (±SD) disc rim area in eyes with normal visual fields (1.10 ± 0.31 mm²) was slightly larger than that of eyes with visual field loss (0.90 ± 0.33 mm²). The mean disc rim area in the control group (1.49 ± 0.19 mm²) was significantly different from both sets of eyes in the asymmetric primary open angle glaucoma patients (p = 0.000). These findings support the hypothesis that loss of the optic disc rim can be detected before perimetric abnormalities develop in patients with glaucoma.     

The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry

AIMS: To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT). METHODS: CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. RESULTS: A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 mum increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p< or = 0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects. CONCLUSION: IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen.     

测量中央角膜厚度在青光眼诊治中的意义

眼压测量值是诊治青光眼的基本数据.近年来的研究结果 表明Goldmann压平眼压计等多种眼压计的测量值与中央角膜厚度(CCT)相关.由于人群中CCT个体差异明显,因此测量CCT对于了解患者实际眼压水平具有重要意义.此外,最新研究结果 显示薄角膜是高眼压症发展成为原发性开角型青光眼的独立危险因素,但薄角膜是否为发生青光眼性损伤的危险因素之一尚在争论中.有学者认为CCT的测量应当成为诊治青光眼的常规检查方法 之一.(中华眼科杂志,2009,45:184-188)     

Comparison of central corneal thickness in patients participating in a glaucoma screening programme and those who were examined in the glaucoma unit

BACKGROUND: The aim of this study was to compare central corneal thickness (CCT) and intraocular pressure in patients participating in a glaucoma screening programme and patients who were examined in the glaucoma unit. MATERIALS AND METHODS: 406 patients of a glaucoma screening programme (Salzburg-Moorfields collaborative glaucoma study) were included in this study. In addition a group of 406 patients who were admitted to the glaucoma clinic for a detailed glaucoma examination was included (outpatient clinic group). In all participants central corneal thickness (CCT) was measured and possible relations of CCT within the study groups were statistically analysed. RESULTS: In the population screening group the mean central corneal thickness in normal subjects was 536+/-4.3 microm, in patients with ocular hypertension (OHT) 552+/-5.7 microm, patients suffering from a normal tension glaucoma (NTG) showed a mean CCT of 534+/-14.2 microm and those with primary open angle glaucoma (POAG) had a value of 521+/-17.9 microm. In the 'outpatient clinic group' the OHT subgroup had a mean CCT of 553+/-6.8 microm, the NTG subgroup of 529+/-26.5 microm and the one with POAG had a mean of 527+/-19.8 microm. In addition, CCT was measured in all glaucoma patients whose "partner" eye was healthy (544+/-5 microm) and included in this study as part of the normal subgroup. In both groups (screening group and outpatient group), CCT was significantly higher in OHT patients than in normals. In contrast, no statistically significant difference between normals and NTG or POAG patients was detected. Intraocular pressure was significantly lower in the screening groups than in the other ones. CONCLUSIONS: Our data confirm the previously published results concerning OHT and healthy subjects. In this study no significant difference between NTG or POAG subjects and normal eyes was detected. The lower IOP in the screening population can be explained by the fact that patients contacting the screening program are self selected whereas patients of the glaucoma unit are admitted by practising ophthalmologists and are, therefore, rather advanced cases or carrying special risk factors.     

Timolol increased retrobulbar flow velocities in untreated glaucoma eyes but not in ocular hypertension

PURPOSE: To investigate retrobulbar blood flow velocities and the effects of topical timolol treatment in eyes with newly detected, previously untreated open angle glaucoma or ocular hypertension. METHODS: Fifteen eyes with open angle glaucoma (OAG) and 12 eyes with ocular hypertension (OH), in the same number of patients, all untreated and newly detected, were examined with colour Doppler imaging of retrobulbar vessels before and after 1 month of topical timolol treatment (0.5% Timoptic BID). RESULTS: Baseline central retinal artery end diastolic velocity was lower (48%, p=0.0002) and resistive index higher (7.6%, p=0.018) in the OAG group than in the OH group. In the glaucoma group mean end diastolic velocity increased by 41%, (p=0.006) while resistive index decreased by 5.8%, (p=0.02) on treatment, while no significant changes were seen in the OH group. Blood flow velocities in the ophthalmic artery did not change with treatment. Baseline IOP and IOP reduction did not differ between OAG and OH group. CONCLUSION: Peripheral resistance to blood flow was found to be increased in untreated glaucoma eyes as compared to a similar group of eyes with ocular hypertension. Timolol treatment diminished resistance significantly in the glaucoma group, but not in the ocular hypertension group. Thus the two groups responded differently to timolol treatment. The reaction to IOP lowering treatment could indicate defective autoregulation in the glaucoma group.