Visual conditions affecting eye growth alter diurnal levels of vitreous DOPAC.

In chicks, the diurnal patterns of retinal dopamine synthesis and release are associated with refractive development. To assess the within-day patterns of dopamine release, we assayed vitreal levels of DOPAC (3,4-dihydroxyphenylacetic acid) using high performance liquid chromatography with electrochemical detection, at 4-h intervals over 24 h in eyes with experimental manipulations that change ocular growth rates. Chicks were reared under a 12 h light/12 h dark cycle; experiments began at 12 days of age. Output was assessed by modelling using the robust variance structure of Generalized Estimating Equations. Continuous spectacle lensdefocus or form deprivation: One group experienced non-restricted visual input to both eyes and served as untreated "normal" controls. Three experimental cohorts underwent monocular visual alterations known to alter eye growth and refraction: wearing a diffuser, a negative lens or a positive lens. After one full day of device-wear, chicks were euthanized at 4-h intervals over 24 h (8 birds per time/condition). Brief hyperopic defocus: Chicks wore negative lenses for only 2 daily hours either in the morning (starting at ZT 0; n = 16) or mid-day (starting at ZT 4; n = 8) for 3 days. Vitreal DOPAC was assayed. In chicks with bilateral non-restricted vision, or with continuous defocus or form-deprivation, there was a diurnal variation in vitreal DOPAC levels for all eyes (p < 0.001 for each). In normal controls, DOPAC was highest during the daytime, lowest at night, and equivalent for both eyes. In experimental groups, regardless of whether experiencing a growth stimulatory input (diffuser; negative lens) or growth inhibitory input (positive lens), DOPAC levels were reduced compared both to fellow eyes and to those of normal controls (p < 0.001 for each). These diurnal variations in vitreous DOPAC levels under different visual conditions indicate a complexity for dopaminergic mechanisms in refractive development that requires further study.

The King-Devick test as a determinant of head trauma and concussion in boxers and MMA fighters.

OBJECTIVE: Sports-related concussion has received increasing attention as a cause of short- and long-term neurologic symptoms among athletes. The King-Devick (K-D) test is based on measurement of the speed of rapid number naming (reading aloud single-digit numbers from 3 test cards), and captures impairment of eye movements, attention, language, and other correlates of suboptimal brain function. We investigated the K-D test as a potential rapid sideline screening for concussion in a cohort of boxers and mixed martial arts fighters. METHODS: The K-D test was administered prefight and postfight. The Military Acute Concussion Evaluation (MACE) was administered as a more comprehensive but longer test for concussion. Differences in postfight K-D scores and changes in scores from prefight to postfight were compared for athletes with head trauma during the fight vs those without. RESULTS: Postfight K-D scores (n = 39 participants) were significantly higher (worse) for those with head trauma during the match (59.1 ± 7.4 vs 41.0 ± 6.7 seconds, p < 0.0001, Wilcoxon rank sum test). Those with loss of consciousness showed the greatest worsening from prefight to postfight. Worse postfight K-D scores (r(s) = -0.79, p = 0.0001) and greater worsening of scores (r(s) = 0.90, p < 0.0001) correlated well with postfight MACE scores. Worsening of K-D scores by ≥5 seconds was a distinguishing characteristic noted only among participants with head trauma. High levels of test-retest reliability were observed (intraclass correlation coefficient 0.97 [95% confidence interval 0.90-1.0]). CONCLUSIONS: The K-D test is an accurate and reliable method for identifying athletes with head trauma, and is a strong candidate rapid sideline screening test for concussion.

Meta-regression with partial information on summary trial or patient characteristics.

We present a model for meta-regression in the presence of missing information on some of the study level covariates, obtaining inferences using Bayesian methods. In practice, when confronted with missing covariate data in a meta-regression, it is common to carry out a complete case or available case analysis. We propose to use the full observed data, modelling the joint density as a factorization of a meta-regression model and a conditional factorization of the density for the covariates. With the inclusion of several covariates, inter-relations between these covariates are modelled. Under this joint likelihood-based approach, it is shown that the lesser assumption of the covariates being Missing At Random is imposed, instead of the more usual Missing Completely At Random (MCAR) assumption. The model is easily programmable in WinBUGS, and we examine, through the analysis of two real data sets, sensitivity and robustness of results to the MCAR assumption.

Vision related quality of life in multiple sclerosis: correlation with new measures of low and high contrast letter acuity.

OBJECTIVE: To examine the relation between low contrast letter acuity, a new visual function test for multiple sclerosis (MS) trials, and vision targeted health related quality of life (HRQOL). METHODS: Patients in this cross sectional study were part of an ongoing investigation of visual function in MS. Patients were tested binocularly using low contrast letter acuity and Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity (VA) charts. The 25 Item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25), 10 Item Neuro-Ophthalmic Supplement to the NEI-VFQ-25, Impact of Visual Impairment Scale and Short Form 36 Health Survey (SF-36) were administered. RESULTS: Among 167 patients, mean age was 48 (10) years, with median Expanded Disability Status Scale (EDSS) 2.0 (range 1.0-7.5), and median binocular Snellen acuity equivalent (ETDRS charts) 20/16 (range 20/12.5 to 20/100). Reductions in vision specific HRQOL were associated with lower (worse) scores for low contrast letter acuity and VA (p<0.001, linear regression, accounting for age). Two line differences in visual function were associated, on average, with >4 point (6.7-10.9 point) worsening in the NEI-VFQ-25 composite score, reductions that are considered clinically meaningful. Scores for the 10 Item Neuro-Ophthalmic Supplement to the NEI-VFQ-25 also correlated well with visual function. Associations between reduced low contrast acuity and worse vision targeted HRQOL remained significant in models accounting for high contrast VA, EDSS and history of acute optic neuritis. CONCLUSIONS: Low contrast letter acuity scores correlate well with HRQOL in MS. Two line differences in scores for low contrast acuity and VA reflect clinically meaningful differences in vision targeted HRQOL. Low contrast acuity testing provides information on patient reported aspects of vision, supporting use of these measures in MS clinical trials.

Contrast letter acuity as a visual component for the Multiple Sclerosis Functional Composite.

BACKGROUND: Visual dysfunction is one of the most common causes of disability in multiple sclerosis (MS). The Multiple Sclerosis Functional Composite (MSFC), a new clinical trial outcome measure, does not currently include a test of visual function. OBJECTIVE: To examine contrast letter acuity as a candidate visual function test for the MSFC. METHODS: Binocular contrast letter acuity testing (Sloan charts) was performed in a subgroup of participants from the International Multiple Sclerosis Secondary Progressive Avonex Controlled Trial (IMPACT Substudy) and in MS patients and disease-free control subjects from a cross-sectional study of visual outcome measures (Multiple Sclerosis Vision Prospective cohort [MVP cohort]). High-contrast visual acuity was measured in both studies; MVP cohort participants underwent additional binocular testing for contrast sensitivity (Pelli-Robson chart), color vision (D-15 desaturated test), and visual field (Esterman test, Humphrey Field Analyzer II). RESULTS: Contrast letter acuity (Sloan charts, p < 0.0001, receiver operating characteristic curve analysis) and contrast sensitivity (Pelli-Robson chart, p = 0.003) best distinguished MS patients from disease-free control subjects in the MVP cohort. Correlations of Sloan chart scores with MSFC and Expanded Disability Statue Scale (EDSS) scores in both studies were significant and moderate in magnitude, demonstrating that Sloan chart scores reflect visual and neurologic dysfunction not entirely captured by the EDSS or MSFC. CONCLUSIONS: Among clinical measures, contrast letter acuity (Sloan charts) and contrast sensitivity (Pelli-Robson chart) demonstrate the greatest capacity to identify binocular visual dysfunction in MS. Sloan chart testing also captures unique aspects of neurologic dysfunction not captured by current EDSS or MSFC components, making it a strong candidate visual function test for the MSFC.

Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome.

PURPOSE: To determine macular pigment (MP) in patients with inherited retinal degeneration and the response of MP and vision to supplementation of lutein. METHODS: Patients with retinitis pigmentosa (RP) or Usher syndrome and normal subjects had MP optical density profiles measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity, and retinal thickness (by optical coherence tomography [OCT]) were quantified. The effects on MP and central vision of 6 months of lutein supplementation at 20 mg/d were determined. RESULTS: MP density in the patients as a group did not differ from normal. Among patients with lower MP, there was a higher percentage of females, smokers, and light-colored irides. Disease expression tended to be more severe in patients with lower MP. Inner retinal thickness by OCT correlated positively with MP density in the patients. After supplementation, all participants showed an increase in serum lutein. Only approximately half the patients showed a statistically significant increase in MP. Retinal nonresponders had slightly greater disease severity but were otherwise not distinguishable from responders. Central vision was unchanged after supplementation. CONCLUSIONS: Factors previously associated with lower or higher MP density in normal subjects showed similar associations in RP and Usher syndrome. In addition, MP in patients may be affected by stage of retinal disease, especially that leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in many but not all patients. There was no change in central vision after 6 months of lutein supplementation, but long-term influences on the natural history of these retinal degenerations require further study.

Corneal surface area: an index of anterior segment growth.

Corneal surface area and perimeter were assessed as novel indices to monitor anterior segment growth, using chicks reared under different photoperiods. We obtained central and mid-peripheral corneal curvatures using photokeratometry. Anatomical tracings of the anterior corneal surface also were made from freeze-dried non-fixed preparations of the anterior segments of the same eyes. Using either photokeratometry or anatomical data, the profile of the anterior corneal surface was fit to a general equation for conical sections; corneal surface area was estimated from surfaces of revolution. Optical techniques modeled the chick cornea as a circle or as an ellipse closely resembling a circle. The anatomical technique, in contrast, modeled the chick corneal profile as a hyperbola. Potential explanations of this discrepancy are discussed. Regardless of which model is evaluated, the corneal surface area and perimeter of two-week-old chicks are affected by the photoperiod of rearing. Corneal surface area in particular proved more sensitive than conventional measurements in identifying anterior segment effects of rearing under different photoperiods. Analysis of corneal area may prove useful in evaluating the mechanisms governing anterior segment growth.

Laser burn intensity and the risk for choroidal neovascularization in the CNVPT Fellow Eye Study.

OBJECTIVE: To explore the relationship between laser burn intensity and the subsequent risk for development of choroidal neovascularization (CNV) in eyes assigned to the treatment group of the Fellow Eye Study (FES) of the Choroidal Neovascularization Prevention Trial (CNVPT), using computerized methods for laser burn quantitation, and to examine the association between laser burn intensity and (1) drusen reduction and (2) visual acuity. METHODS: Color fundus images before and immediately after laser treatment in the CNVPT FES were available for 53 of 59 eyes. Prelaser and postlaser treatment images were analyzed using custom-developed computer software, allowing for laser burn identification and quantitation. As measures of laser burn intensity, we derived integrated burn rating (IBR) (the integral of the normalized intensity difference divided by the burn pixels), and the maximum burn intensity (MAX). We identified CNV using fluorescein angiography. A Cox proportional hazards model was fit to the time to development of CNV. Baseline and 6-month color photographs were used to determine reduction in drusen. Visual acuity was measured using a standardized protocol. RESULTS: The IBR and MAX spanned 4.5 logarithm units. After adjusting for smoking history and predominant drusen size, the risk ratio for CNV per logarithm unit of increasing laser burn intensity for each measure was 2.0 (P =.05) for MAX and 1.7 (P =.07) for IBR. When patients were divided into high- and low-intensity treatment groups of equal size, the high-intensity group had more drusen reduction (57% vs 32%; P =.14). There was no effect of laser intensity on change in visual acuity at 6 months. CONCLUSION: Higher-intensity prophylactic laser applications appear to be associated with a greater risk for development of CNV and with more extensive drusen reduction.

Visual loss in children with neurofibromatosis type 1 and optic pathway gliomas: relation to tumor location by magnetic resonance imaging.

PURPOSE: To examine the potential for visual acuity loss, and its relation to extent and location of optic pathway gliomas in a cohort of children with neurofibromatosis type 1 studied with magnetic resonance imaging. METHODS: We reviewed the neuro-ophthalmologic records and brain/orbital magnetic resonance imaging scans for 43 consecutive pediatric patients with neurofibromatosis type 1 and optic pathway gliomas who were followed at the Children's Hospital of Philadelphia. The presence of visual loss, defined as abnormal visual acuity for age in one or both eyes, was determined. Optic pathway gliomas were classified by tumor extent and location according to involvement of the optic nerves, chiasm, and postchiasmal structures by magnetic resonance imaging. RESULTS: Involvement of the optic tracts and other postchiasmal structures at tumor diagnosis was associated with a significantly higher probability of visual acuity loss (P =.048, chi-square test). Visual loss was noted in 20 of 43 patients (47%) at a median age of 4 years; however, three patients developed visual acuity loss for the first time during adolescence. CONCLUSIONS: In pediatric patients with neurofibromatosis type 1 and optic pathway gliomas, the likelihood of visual loss is dependent on the extent and location of the tumor by magnetic resonance imaging and is particularly associated with involvement of postchiasmal structures. Furthermore, older age during childhood (adolescence) does not preclude the occurrence of visual loss. Close follow-up beyond the early childhood years, particularly for those with postchiasmal tumor, is recommended.

Portable pupillography of the swinging flashlight test to detect afferent pupillary defects.

OBJECTIVE: To investigate the ability of a portable, personal computer-driven, pupillometer to record the pupillary response curve during the swinging flashlight test. Also, to determine whether these response curves can be used to identify and quantify relative asymmetry in the pupillary light reflex between eyes in healthy volunteers with simulated afferent pupil defects (APDs) and patients with optic neuropathies. DESIGN: Comparative, observational case series and instrument validation. PARTICIPANTS: Healthy volunteers with no known ocular disease and patients (n = 20) with various optic neuropathies noted to have relative APDs on examination. METHODS: Pupillary response curves of the right eye were recorded with a portable, electronic, infrared pupillometer from healthy volunteers (with and without simulated APDs) and patients with APDs while the light stimulus alternated between eyes, simulating the swinging flashlight test. Simulated APDs in healthy volunteers were created with increasingly dense neutral density filters in front of the left eye. MAIN OUTCOME MEASURES: Differences in constriction amplitude, latency, and constriction velocity of the pupillary response with right eye stimulation versus left eye stimulation in both groups of subjects. RESULTS: A significant correlation between neutral density filter strength and intereye differences was seen for all measurement parameters in volunteers with simulated APDs. Depending on the measurement parameter and stimulus intensity, simulated APDs of 0.6 log units or more could be distinguished from normal responses. Clinically graded true APDs had intereye differences similar to simulated APDs of the same density. Those with real and simulated APDs of 0.9 log units or more could be distinguished from healthy volunteers with 80% sensitivity and 92% specificity. Responses from those with real and simulated small APDs of 0.3 to 0.6 log units could not be distinguished reliably. CONCLUSIONS: Portable, personal-computer driven, electronic, infrared pupillography can record the swinging flashlight test accurately and identify large afferent pupillary defects. An affordable, portable, reliable device for identifying relative APDs would be useful in the identification and follow-up of patients with neurogenic vision loss.

Impact of pill organizers and blister packs on adherence to pill taking in two vitamin supplementation trials.

The impact of pill organizers on pill taking was determined in the Trial of Antioxidant Vitamins C and E (TRACE) Study, a factorial trial of vitamin C and vitamin E supplementation in 184 individuals. Participants were recruited in 1996-1997 and randomized to one of two groups (pill organizer or no organizer) and to one of four supplement groups for 2 months. The pill count (observed/expected X 100%) distribution was similar in the organizer and no organizer group for both vitamins. Mean differences in changes in serum vitamin levels between active and placebo groups did not differ by pill organizer use. The impact of pill organizers and blister packs was compared in another trial, the Vitamins, Teachers, and Longevity (VITAL) Study, in 297 individuals randomized in 1993-1994 to receive study pills either in blister packs or in pill organizers and to take one of two supplements. Among those with lower adherence, the pill count distribution in the blister-pack group exceeded that in the organizer group. Mean differences in serum vitamin E levels between active and placebo groups did not differ by types of pill packaging. In summary, use of blister packs, but not pill organizers, improved adherence as measured by pill counts among those with lower adherence. Neither pill delivery system improved adherence as measured by serum vitamin levels.

New low-contrast vision charts: reliability and test characteristics in patients with multiple sclerosis.

The quantitative assessment of visual function in multiple sclerosis (MS) clinical trials has been limited to Snellen visual acuity. The purpose of this study was to examine the inter-rater reliability and test characteristics of a new visual outcome measure, the Low-Contrast Sloan Letter Charts, in patients with MS and visually-asymptomatic volunteers. Contrast letter acuity scores (letter scores) were measured at each of four contrast levels (100, 5, 1.25 and 0.6%) by two independent raters. Inter-rater agreement was described with the intraclass correlation coefficient (ICC) and comparison of mean scores. Excellent inter-rater agreement (ICC=0.86 - 0.95) was demonstrated at each contrast level among MS patients (n=100) and visually-asymptomatic volunteers (n=33). Average letter scores at the lowest contrast level (0.6%) were highly variable in the MS group, even among patients with visual acuities of 20/20 or better, and among those who required no assistance for ambulation. Low-Contrast Sloan Letter Chart testing is a highly reliable method of visual assessment, and provides information on an aspect of neurologic impairment in MS which is not captured by Snellen visual acuity or ambulation status. This new method demonstrates excellent potential as a visual function outcome measure for future MS clinical trials.

One-year outcomes of panretinal photocoagulation in proliferative diabetic retinopathy.

PURPOSE: To describe the clinical features and complications of diabetic retinopathy, visual acuity, and number of repeat treatments after panretinal photocoagulation for proliferative diabetic retinopathy in a tertiary care center. METHODS: A cohort study was conducted with data collection from medical records of patients undergoing panretinal photocoagulation between 1985 and 1995 at the Scheie Eye Institute; 297 eyes of 186 patients were eligible for study. RESULTS: The presence of neovascularization of the disk at baseline, an earlier onset of diabetes, and a shorter duration of disease before panretinal photocoagulation were the strongest risk factors for needing an additional panretinal photocoagulation treatment. Sixty-two percent of eyes with poor visual acuity (< or =20/200) at baseline still had poor visual acuity at 1 year, and 76% with good visual acuity (> or =20/40) at baseline maintained good visual acuity at 1 year. Poor vision at baseline was the only risk factor for having poor vision at 1 year. Vitreous hemorrhage was present in 44% of eyes at baseline. New vitreous hemorrhage developed in 37% of eyes during the first year after panretinal photocoagulation. A traction retinal detachment was present in 4% of eyes at baseline and newly developed in 6% of eyes during follow-up. A repeat panretinal photocoagulation treatment was performed in 39% of eyes after initial treatment. A vitrectomy was performed in 10% of eyes from baseline through the 1-year follow-up visit. CONCLUSIONS: The data from this study are useful for counseling patients with respect to likely visual outcome, possibility of major complications from proliferative diabetic retinopathy, and the chance of undergoing additional laser treatment after panretinal photocoagulation.

Psychophysical evidence for rod vulnerability in age-related macular degeneration.

PURPOSE: To determine whether there is rod system dysfunction in the central retina of patients with age-related macular degeneration (AMD). METHODS: Dark-adapted sensitivity (500-nm stimulus) and light-adapted sensitivity (600 nm) were measured psychophysically at 52 loci in the central 38 degrees (diameter) of retina in 80 patients with AMD, and results were compared with those from older adult normal controls. All dark-adapted data were corrected for preretinal absorption. RESULTS: Mean field dark-adapted sensitivity was significantly lower in AMD patients as a group than in normal subjects. Within the AMD group were subsets of patients with normal mean dark- and light-adapted sensitivities; reduced dark-adapted sensitivities without detectable light-adapted losses; both types of losses; and, least commonly, only light-adapted losses. Regional retinal analyses of the dark-adapted deficit indicated the greatest severity was 2 degrees to 4 degrees or approximately 1 mm from the fovea, and the deficit decreased with increasing eccentricity. CONCLUSIONS: These psychophysical results are consistent with histopathologic findings of a selective vulnerability for parafoveal rod photoreceptors in AMD. The different patterns of rod and cone system losses among patients at similar clinical stages reinforces the notion that AMD is a group of disorders with underlying heterogeneity of mechanism of visual loss. Dark-adapted macula-wide testing may be a useful complement to the more traditional outcome measures of fundus pathology and foveal cone-based psychophysics in future AMD trials.

Self-reported visual dysfunction in multiple sclerosis: results from the 25-Item National Eye Institute Visual Function Questionnaire (VFQ-25).

Visual impairment is one of the most common clinical manifestations of Multiple Sclerosis (MS), and is strongly related to overall health-related quality of life (HRQOL) in MS and other disorders. However, the assessment of vision-specific HRQOL in patients with MS has been limited. The purpose of this study was to examine self-reported visual dysfunction in a clinically heterogeneous MS cohort using the 25-Item National Eye Institute Visual Function Questionnaire (VFQ-25). The VFQ-25 was administered by telephone interview to a subset of participants in a follow-up study to a phase III trial of interferon beta-1a for relapsing-remitting MS. Mean VFQ-25 composite scores and selected sub-scale scores were significantly lower (worse) among patients in our MS cohort (n=35) compared with a published reference group of patients with no history of chronic eye disease (n= 118). These differences were observed despite a relatively younger age and tighter distribution of binocular visual acuities in the MS cohort Patients with MS in this study thus demonstrated a greater degree of self-reported visual dysfunction, as measured by the VFQ-25, compared with an eye disease-free reference group. The VFQ-25 is a potentially useful measure of vision-specific HRQOL in patients with MS.

Laser-induced drusen reduction improves visual function at 1 year. Choroidal Neovascularization Prevention Trial Research Group.

OBJECTIVE: To describe the relationship of laser-induced drusen reduction to change in visual function at 1 year among patients enrolled in the Choroidal Neovascularization Prevention Trial (CNVPT). DESIGN: Comparison of groups with and without drusen reduction; follow-up of a randomized controlled trial. PARTICIPANTS: Evaluations of drusen and visual acuity at baseline and at 1 year were performed for 351 eyes of the 432 eyes enrolled in the CNVPT Bilateral Drusen Study and Fellow Eye Study (81%). One hundred eighty-four eyes were assigned to observation, and 167 eyes were assigned to laser treatment. Eyes with conditions that precluded an analysis of drusen reduction, such as those that developed choroidal neovascularization (CNV) within the first year, are excluded from this analysis. METHODS: Change in macular drusen between initial visit and after 1 year was assessed by side-by-side grading by evaluators masked to information on visual function. Visual acuity, contrast threshold, and critical print size were measured by certified visual function examiners. MAIN OUTCOME MEASURES: Change in visual acuity is the primary outcome. Change in contrast threshold and change in critical print size are secondary outcome measures. RESULTS: Laser-treated eyes with 50% or more drusen reduction at 1 year had more 1- and 2-line increases in visual acuity and less losses in visual acuity compared with laser-treated eyes with less drusen reduction or with observed eyes (P = 0.001). Similar improvements were noted for contrast threshold but not critical print size at 1 year. CONCLUSIONS: Laser-induced drusen reduction is associated with improved visual acuity and contrast sensitivity in eyes at 1 year. Longer term effects of laser-induced drusen reduction on visual function require additional observation. The overall potential value of laser treatment in eyes with high-risk drusen requires consideration of not only short-term effects on vision but also the effects of CNV and atrophy on vision.

Optic nerve blood flow in glaucoma: effect of systemic hypertension.

PURPOSE: To investigate optic nerve head blood flow in patients with glaucoma and to assess the effect of systemic hypertension. METHODS: This study included 24 eyes of 24 patients with primary open-angle glaucoma. Eleven of these patients had a history of systemic hypertension. Results in patients with glaucoma were compared with those of 13 eyes of 13 age-matched normal controls. Determinations of relative optic nerve head blood velocity, volume, and flow were obtained with laser Doppler flowmetry in the superotemporal and inferotemporal neuroretinal rim and also in the cup. Means of the velocity, volume, and flow of these three measurement sites were calculated for each subject. RESULTS: Mean overall optic nerve head blood flow was 29% lower in glaucoma patients than in normal controls (t test, P < .001). This decrease in flow was mainly caused by a decrease of 23% in mean blood velocity (P < .001). Mean flow in glaucoma patients without systemic hypertension was 26% lower than that of glaucoma patients with hypertension (Tukey honest significant difference test, P = .05). A significant direct correlation was observed between mean flow and mean blood pressure (R = 0.51, P < .02). CONCLUSIONS: Optic nerve blood flow is reduced in glaucoma patients. Glaucoma patients without systemic hypertension have lower optic nerve blood flow than those with hypertension. Our results raise concerns that treatment of systemic hypertension may further decrease optic nerve blood flow in glaucoma patients.