Showing papers by "Harry A. Quigley published in 2006"

The number of people with glaucoma worldwide in 2010 and 2020

Abstract: Aim: To estimate the number of people with open angle (OAG) and angle closure glaucoma (ACG) in 2010 and 2020. Methods: A review of published data with use of prevalence models. Data from population based studies of age specific prevalence of OAG and ACG that satisfied standard definitions were used to construct prevalence models for OAG and ACG by age, sex, and ethnicity, weighting data proportional to sample size of each study. Models were combined with UN world population projections for 2010 and 2020 to derive the estimated number with glaucoma. Results: There will be 60.5 million people with OAG and ACG in 2010, increasing to 79.6 million by 2020, and of these, 74% will have OAG. Women will comprise 55% of OAG, 70% of ACG, and 59% of all glaucoma in 2010. Asians will represent 47% of those with glaucoma and 87% of those with ACG. Bilateral blindness will be present in 4.5 million people with OAG and 3.9 million people with ACG in 2010, rising to 5.9 and 5.3 million people in 2020, respectively. Conclusions: Glaucoma is the second leading cause of blindness worldwide, disproportionately affecting women and Asians.

Visual Field Defects and Retinal Ganglion Cell Losses in Patients With Glaucoma

Abstract: Objective To determine whether the structure-function relationships for glaucoma in humans and experimental glaucoma in monkeys are similar. Methods The study was based on retinal ganglion cell density and visual thresholds in patients with documented glaucoma. Data were analyzed with a model that predicted ganglion cell density from standard clinical perimetry, which was then compared with histologic cell counts. Results The model, without free parameters, produced accurate and relatively precise quantification of ganglion cell density associated with visual field defects. For 437 sets of data, the unity correlation for predicted vs measured cell density had a coefficient of determination of 0.39. The mean absolute deviation of the predicted vs measured values was 2.59 decibels (dB), and the mean ± SD of the distribution of residual errors of prediction was −0.26 ± 3.22 dB. Conclusions Visual field defects based on standard clinical perimetry are proportional to neural losses caused by glaucoma. Clinical Relevance The evidence for quantitative structure-function relationships provides a scientific basis for interpreting glaucomatous neuropathy from visual thresholds and supports the application of standard perimetry to establish the stage of the disease.

Manometric calibration and comparison of TonoLab and TonoPen tonometers in rats with experimental glaucoma and in normal mice.

Abstract: PURPOSE To compare the TonoPen and TonoLab tonometers to each other and to manometrically set intraocular pressure (IOP) in the eyes of normal mice, normal rats, and rats with chronic IOP elevation. METHODS The measurement of IOP by the TonoPen and TonoLab tonometers was made in 21 normal rat eyes, 10 normal mouse eyes, and 16 rats that had either 2 or 4-week experimental glaucoma. IOP was varied from 10 to 50 mm Hg in steps of 10 mm Hg under conditions in which the eye was either open or closed to the reservoir controlling IOP. RESULTS In normal rat eyes, TonoPen overestimated manometric IOP at 10 mm Hg and underestimated it by up to 6 mm Hg at higher IOP, whereas the TonoLab matched set IOP within 1 mm Hg. In glaucoma rat eyes, the TonoLab accurately reflected manometric IOP under open stopcock conditions (linear regression: y = 0.99x -0.62, R = 0.98), whereas in the closed stopcock condition, IOP measured lower at the higher IOP levels (P = 0.0059, paired t test). In uncannulated rat glaucoma eyes, the tonometer used first gave higher IOP [paired t test, P = 0.015 (TonoLab first); P = 0.005 (TonoPen first)]. In normal mouse eyes under the open stopcock condition, the TonoLab nearly matched manometric IOP (linear regression: y = 0.98x + 1.57, R = 0.98). CONCLUSIONS In mouse and rat eyes, including rats with chronic IOP elevation, the TonoLab accurately reflected manometrically set IOP in an efficient manner.

Asymmetries and visual field summaries as predictors of glaucoma in the ocular hypertension treatment study

Abstract: series of papers. 3‐5 This study complements the previous baseline risk factor analysis through an extended examination of visual field data and a study of asymmetries between right and left eyes. We thus firstly constructed a monocular measure summarizing visual field thresholds, and this measure outperformed other monocular indices as predictors of POAG. Asymmetric IOP has been shown to be related to glaucoma and to the presence of glaucomatous visual field defects. 6‐8 Asymmetry in static perimetry thresholds has also been shown to reveal early glaucomatous damage. 9 We thus secondly performed binocular analyses to consider the effect of IOP asymmetry and interocular differences in the visual field thresholds on POAG. Throughout this article we use the term “threshold ” as it is commonly used in perimetric investigations where higher thresholds actually signify better sensitivity. We do this to avoid confusion with the clinical literature even though it is at odds with the reciprocal relationship between threshold and sensitivity in the stricter sense of these terms in basic psychophysics. Mean deviation (MD), pattern standard deviation (PSD),

Test-retest variability in structural and functional parameters of glaucoma damage in the glaucoma imaging longitudinal study

Abstract: PurposeTo determine the test-retest variability in perimetric, optic disc, and macular thickness parameters in a cohort of treated patients with established glaucomaPatients and MethodsIn this cohort study, the authors analyzed the imaging studies and visual field tests at the baseline and 6-month

Dirty little secrets.

Abstract: munication between doctor and patient, cost of therapy in time and money, patient attitudes towards health and disease, side-effects of treatment and a host of other risk factors. Some are inherent to OAG and others are similar to those relevant to all disease management. We can learn much from studies of these issues in other chronic diseases. One disturbing finding is the failure of women with OAG to fill prescriptions at the same rate as men do. The cited study detected behaviour from pharmacy data, so it is not clear whether women were being offered fewer prescriptions than men by their doctors, or whether women were not filling prescriptions as often as men were. Either explanation requires our attention. Gender bias was suspected in the application of cardiac surgery, but clinical variation and patient choice may partly explain the conclusion. If women cannot or will not start and continue OAG treatment as often as men, we should learn why this is the case and intervene effectively. We need to develop electronic monitoring systems that are incorporated into eyedrop bottles to study who is cooperating with treatment. These could be used covertly in a research mode, or overtly to assist patients to improve cooperation with treatment. Research is needed to monitor actual behaviour by doctors and patients. In doing so, we will learn what works, so that preferred practice patterns of the future will be evidence-based.

Gaze behavior of the visually impaired during street crossing.

Abstract: PURPOSE: This study explored the gaze patterns of fully sighted and visually impaired subjects during the high-risk activity of crossing the street. METHODS: Gaze behavior of 12 fully sighted subjects, nine with visual impairment resulting from age-related macular degeneration and 12 with impairment resulting from glaucoma, was monitored using a portable eye tracker as they crossed at two unfamiliar intersections. RESULTS: All subject groups fixated primarily on vehicles and crossing elements but changed their fixation behavior as they moved from "walking to the curb" to "standing at the curb" and to "crossing the street." A comparison of where subjects fixated in the 4-second time period before crossing showed that the fully sighted who waited for the light to change fixated on the light, whereas the fully sighted who crossed early fixated primarily on vehicles. Visually impaired subjects crossing early or waiting for the light fixate primarily on vehicles. CONCLUSIONS: Vision status affects fixation allocation while performing the high-risk activity of street crossing. Crossing decision-making strategy corresponds to fixation behavior only for the fully sighted subjects. Language: en

Macular symmetry testing for glaucoma detection.

Abstract: To the Editor: We are writing in reference to the article by Bagga H, Greenfield D, and Knighton R, ‘‘Macular Symmetry Testing for Glaucome Detection’’. We thank the authors for highlighting the concept of measuring macular thickness as a surrogate measure of ganglion cell loss. However, the authors state ‘‘we hypothesized that localized retinal ganglion cell atrophy may occur in the macula producing asymmetric macular thickness across the horizontal retinal meridian.’’ We would like to bring to their attention our article in which we originally proposed the concept of localized ganglion cell atrophy in the macula as well as the concept of measurement of the asymmetry across the horizontal meridian in glaucoma patients. This was done by use of the retinal thickness analyzer, and we commend the authors in demonstrating the same with the OCT. We also appreciate their welldone study and were pleased to see that they also reached similar conclusions using another instrument.

Long–Term Outcomes in Fellow Eyes After Acute Primary Angle Closure in the Contralateral Eye

Abstract: PURPOSE To determine the long-term outcome of the contralateral eye in Asian persons with a unilateral attack of acute primary angle closure (APAC). DESIGN Cross-sectional observational case series. PARTICIPANTS Seventy-nine individuals who were examined from 4 to 10 years after a unilateral episode of APAC at 2 Singapore hospitals. METHODS All subjects underwent a complete eye examination. The optic discs were graded clinically and photographically for the presence of glaucomatous optic neuropathy, and automated visual field tests were assessed for damage. All visual fields and optic nerve photographs (when available) underwent a second evaluation by a masked glaucoma specialist, who assessed whether the changes were compatible with glaucoma. MAIN OUTCOME MEASURES Glaucomatous optic neuropathy, intraocular pressure (IOP), and visual impairment (defined as best-corrected visual acuity of worse than 6/12). RESULTS Ninety of 138 eligible patients (65.2%) with APAC were examined, 79 with unilateral attacks. Subjects were predominantly Chinese (n = 68; 86%). There were 54 females (68%), and mean age was 68.5+/-8.9 years (standard deviation) at the time of APAC, with a mean duration of 6.3+/-1.5 years from the time of the APAC episode to the study examination. The contralateral eyes of 7 patients (8.9%) had definite or probable glaucoma, 2 of whom were felt to have glaucoma in that eye at the time of the attack. Three eyes had markedly cupped optic discs (cup-to-disc ratio > or = 0.9). Thirteen eyes (16.9%) had best-corrected vision worse than 6/12, due to cataract in almost half the cases. Only 1 eye had vision < 6/60, the cause of which was corneal decompensation. One other patient had only a central island remaining with vision of 6/12. Mean IOP of the study participants was 15.7+/-4.7 mmHg, with 6 subjects (7.6%) having undergone trabeculectomy. CONCLUSIONS Definite or probable glaucoma was present at the time of diagnosis in 2 (2.5%) fellow eyes and developed in an additional 5 (6.5%) with a mean follow-up of 6 years. More than 80% of this cohort retained good vision in the contralateral eye, in contrast to the eye that underwent APAC. Unoperated cataract accounted for most of the visual impairment in this group.