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Impaired vision is caused by refractive errors such as nearsightedness, aging, infection, nutritional and metabolic disorders, and trauma. Impaired vision is one of the most common disorders in the world, affecting an estimated 150 million people worldwide. The Global Vision 2020 program sponsored by the World Health Organization hopes to eliminate two thirds of all preventable blindness by 2020.

The article presents information on a study regarding the estimation of the prevalence of nonrefractive visual impairment and describing its relationship with demographic and systemic risk factors including diabetes. The study analyzed data from the National Health and Nutrition Examination Survey which assessed visual problem among U.S. residents. Demographic data were collected at the household interview, including age, sex, ethnicity, years of schooling and income and questions related to diabetes, access to health care and health insurance coverage were also monitored.

Objective: To determine the prevalence, characteristics, and risk factors for myopic retinopathy in a rural population in Northern China. Methods: The Handan Eye Study is a population based study of eye disease in rural Chinese individuals 30 years or older. Eligible residents underwent a detailed ophthalmic examination including standardized visual acuity tests and retinal photography after pupil dilation. Myopic retinopathy was defined to include signs of staphyloma, lacquer cracks, Fuchs spot, and myopic chorioretinal atrophy. Results: Of the 6830 participants, 6603 (96.7%) had gradable photographs in at least 1 eye for assessment of myopic retinopathy. The mean (SD) age was 51.9 (11.8) years. Myopic retinopathy was observed in 60 participants (84 eyes), a person-specific prevalence of 0.9% (95% confidence interval, 0.7%-1.1%). Twenty-four (40.0%) had bilateral disease. Higher myopic retinopathy prevalence was associated with older age (P<.001) and increasing myopic spherical equivalent refractive error (P<.001). Mean (SD) spherical equivalent refraction was -12.3 (6.1) diopters for eyes with myopic retinopathy compared with -1.6 (1.6) diopters in myopic eyes without myopic retinopathy (P<.001). Bilateral blindness or low vision as defined by best-corrected visual acuity was present in 14 participants (24.6%) with myopic retinopathy. Staphyloma was the most frequent myopic retinopathy sign (86.9%), followed by chorioretinal atrophy (56.0%), lacquer cracks (36.9%), and Fuchs spot (14.3%). Conclusions: Myopic retinopathy was detected in 0.9% of rural Chinese individuals 30 years or older. The prevalence of myopic retinopathy was lower than that in the Beijing Eye Study but was similar to white individuals of similar age in the Australian Blue Mountains Eye Study. [ABSTRACT FROM AUTHOR]

Objectives: To describe the measurement of anterior chamber area and anterior chamber volume by anteriorsegment optical coherence tomography and to investigate the association of these parameters with the presence of narrow angles. Methods: This was a cross-sectional study of subjects aged at least 50 years without ophthalmic symptoms recruited from a community clinic. All participants underwent standardized ocular examination and anterior-segment optical coherence tomography. Customized software was used to measure anterior chamber area (cross-sectional area bounded by the corneal endothelium, anterior surface of iris, and lens within the pupil) and anterior chamber volume (calculated by rotating the anterior chamber area 360° around a vertical axis through the midpoint of the anterior chamber area). An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180° on gonioscopy with the eye in the primary position. Results: A total of 1922 subjects were included in the final analyses, 317 (16.5%) of whom had narrow angles. Mean anterior chamber area (15.6 vs 21.1mm2; P<.001) and anterior chamber volume (97.6 vs 142.1 mm3; P<.001) were smaller in eyes with narrow angles compared with those in eyes without narrow angles. After adjusting for age, sex, anterior chamber depth, axial length, and pupil size, smaller anterior chamber area (odds ratio, 53.2; 95% confidence interval, 27.1-104.5) and anterior chamber volume (odds ratio, 40.2; 95% confidence interval, 21.5-75.2) were significantly associated with the presence of narrow angles. Conclusion: Smaller anterior chamber area and anterior chamber volume were independently associated with narrow angles in Singaporeans, even after controlling for other known ocular risk factors. [ABSTRACT FROM AUTHOR]

Objective: To assess the ability of high-definition optical coherence tomography (HD-OCT) to image the anterior chamber angle. Methods: Forty-five consecutive subjects with phakic eyes underwent gonioscopy and anterior chamber angle imaging with HD-OCT adapted with a 60-diopter aspheric lens mounted over the imaging aperture. The patients' fixation was directed to the side using an external fixation light, and scans were taken of the temporal and nasal quadrants. The visibility of angle structures was assessed and the diagnosis of angle closure using HD-OCT was compared with that of gonioscopy. Results: The majority of subjects were Chinese (91.1%) and female (62.2%). Cross-sectional HD-OCT allowed in vivo visualization of the scleral spur in 71 of 90 quadrants (78.9%) and the termination of the Descemet membrane (Schwalbe line) in 84 of 90 quadrants (93.3%). It was possible to image the trabecular mesh work in 56 quadrants (62.2%). Angle closure was observed in 17 eyes with gonioscopy and 12 eyes with HD-OCT (P=.12, McNemar test). The 2 modalities showed good agreement for angle closure diagnosis by quadrant (=0.65). Conclusion: The adapted HD-OCT provided magnified views of the anterior chamber angle and allowed visualization of the Schwalbe line and trabecular meshwork in most eyes. [ABSTRACT FROM AUTHOR]

Objectives: To compare methods to estimate the incidence of visual field progression used by 3 large randomized trials of glaucoma treatment by applying these methods to a common data set of annually obtained visual field measurements of patients with glaucoma followed up for an average of 6 years. Methods: The methods used by the Advanced Glaucoma Intervention Study (AGIS), the Collaborative Initial Glaucoma Treatment Study (CIGTS), and the Early Manifest Glaucoma Treatment study (EMGT) were applied to 67 eyes of 56 patients with glaucoma enrolled in a 10-year natural history study of glaucoma using Program 30-2 of the Humphrey Field Analyzer (Humphrey Instruments, San Leandro, Calif). The incidence of apparent visual field progression was estimated for each method. Extent of agreement between the methods was calculated, and time to apparent progression was compared. Results: The proportion of patients progressing was 11%, 22%, and 23% with AGIS, CIGTS, and EMGT methods, respectively. Clinical assessment identified 23% of patients who progressed, but only half of these were also identified by CIGTS or EMGT methods. The CIGTS and the EMGT had comparable incidence rates, but only half of those identified by 1 method were also identified by the other. Conclusions: The EMGT and CIGTS methods produced rates of apparent progression that were twice those of the AGIS method. Although EMGT, CIGTS, and clinical assessment rates were comparable, they did not identify the same patients as having had field progression. [ABSTRACT FROM AUTHOR]

Objective: To evaluate changes in the speed of pupil constriction and in anterior segment parameters after laser peripheral iridotomy (LPI) in patients with angle closure using anterior segment optical coherence tomography., Methods: In this prospective observational study, videos of pupil and anterior segment changes in response to illumination were captured with real-time video recording using anterior segment optical coherence tomography and were analyzed frame by frame before and after LPI. Customized software was used to measure the speed of pupil constriction and changes in anterior chamber depth and anterior chamber area, as well as iris thickness at 750 μm from the scleral spur, at the sphincter muscle region (0.75 mm from the pupillary margin), and at the mid-iris location (half the distance between the scleral spur and the pupillary margin). Pupil diameter, angle opening distance, and trabecular-iris space area at 500 μm from the scleral spur were determined. The speed of pupil constriction was defined as the rate of pupil diameter change in response to illumination., Results: Twenty-nine patients were included. Most were Chinese (26 of 29 [90%]) and female (18 of 29 [62%]). The anterior chamber area, angle opening distance at 500 μm from the scleral spur, and trabecular-iris space area at 500 μm from the scleral spur were significantly higher after LPI (P < .001). A significant increase was observed in the speed of pupil constriction after LPI (P < .005). In response to illumination, the rate of change in iris thickness at the sphincter muscle region and at 750 μm from the scleral spur was faster after LPI (P < .05). Similarly, an increase was observed in the speed of change of angle-opening distance at 500 μm from the scleral spur in response to illumination after LPI (P < .05)., Conclusions: In patients with angle closure, changes in dynamic iridopupillary behavior are observed after LPI. The speed of pupillary constriction is faster after LPI.

Context: Over the past decade, chronic illnesses with ophthalmic sequelae such as diabetes and diabetic retinopathy have increased., Objectives: To estimate prevalence of nonrefractive visual impairment and to describe its relationship with demographic and systemic risk factors including diagnosed diabetes., Design, Setting, and Participants: The National Health and Nutrition Examination Survey (NHANES) examined a representative sample of the US noninstitutionalized population. In 1999-2002 and 2005-2008, 9471 and 10,480 participants aged 20 years or older received questionnaires, laboratory tests, and physical examinations. Visual acuity of less than 20/40 aided by autorefractor was classified as nonrefractive visual impairment., Main Outcome Measure: Nonrefractive visual impairment., Results: Weighted prevalence of nonrefractive visual impairment increased 21% among US adults aged 20 years and older from 1.4% in 1999-2002 to 1.7% in 2005-2008 (P = .03); and increased 40% among non-Hispanic whites aged 20-39 years from 0.5% to 0.7% (P = .008). In multivariable analyses, statistically significant risk factors for nonrefractive visual impairment in 1999-2002 included age (per year odds ratio [OR], 1.07; 95% CI, 1.05-1.09), poverty (OR, 2.18; 95% CI, 1.31-3.64), lack of insurance (OR, 1.85; 95% CI, 1.16-2.95), and diabetes with 10 or more years since diagnosis (OR, 1.93; 95% CI, 1.15-3.25). In 2005-2008, risk factors included age (OR, 1.05; 95% CI, 1.04-1.07), poverty (OR, 2.23; 95% CI, 1.55-3.22), education less than high school (OR, 2.11; 95% CI, 1.54-2.90), and diabetes with 10 or more years since diagnosis (OR, 2.67; 95% CI, 1.64-4.37). Prevalence of diabetes with 10 or more years since diagnosis increased 22% overall from 2.8% to 3.6% (P = .02); and 133% among non-Hispanic whites aged 20-39 years from 0.3% to 0.7% (P < .001)., Conclusion: Prevalence of nonrefractive visual impairment was significantly higher in 2005-2008 than in 1999-2002 and may be attributable, in part, to higher prevalence of diabetes, an associated risk factor that increased in prevalence during this time period.

Objective: To determine the prevalence, characteristics, and risk factors for myopic retinopathy in a rural population in Northern China., Methods: The Handan Eye Study is a population-based study of eye disease in rural Chinese individuals 30 years or older. Eligible residents underwent a detailed ophthalmic examination including standardized visual acuity tests and retinal photography after pupil dilation. Myopic retinopathy was defined to include signs of staphyloma, lacquer cracks, Fuchs spot, and myopic chorioretinal atrophy., Results: Of the 6830 participants, 6603 (96.7%) had gradable photographs in at least 1 eye for assessment of myopic retinopathy. The mean (SD) age was 51.9 (11.8) years. Myopic retinopathy was observed in 60 participants (84 eyes), a person-specific prevalence of 0.9% (95% confidence interval, 0.7%-1.1%). Twenty-four (40.0%) had bilateral disease. Higher myopic retinopathy prevalence was associated with older age (P < .001) and increasing myopic spherical equivalent refractive error (P < .001). Mean (SD) spherical equivalent refraction was -12.3 (6.1) diopters for eyes with myopic retinopathy compared with -1.6 (1.6) diopters in myopic eyes without myopic retinopathy (P < .001). Bilateral blindness or low vision as defined by best-corrected visual acuity was present in 14 participants (24.6%) with myopic retinopathy. Staphyloma was the most frequent myopic retinopathy sign (86.9%), followed by chorioretinal atrophy (56.0%), lacquer cracks (36.9%), and Fuchs spot (14.3%)., Conclusions: Myopic retinopathy was detected in 0.9% of rural Chinese individuals 30 years or older. The prevalence of myopic retinopathy was lower than that in the Beijing Eye Study but was similar to white individuals of similar age in the Australian Blue Mountains Eye Study.

Objectives: To describe the measurement of anterior chamber area and anterior chamber volume by anterior-segment optical coherence tomography and to investigate the association of these parameters with the presence of narrow angles., Methods: This was a cross-sectional study of subjects aged at least 50 years without ophthalmic symptoms recruited from a community clinic. All participants underwent standardized ocular examination and anterior-segment optical coherence tomography. Customized software was used to measure anterior chamber area (cross-sectional area bounded by the corneal endothelium, anterior surface of iris, and lens within the pupil) and anterior chamber volume (calculated by rotating the anterior chamber area 360° around a vertical axis through the midpoint of the anterior chamber area). An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180° on gonioscopy with the eye in the primary position., Results: A total of 1922 subjects were included in the final analyses, 317 (16.5%) of whom had narrow angles. Mean anterior chamber area (15.6 vs 21.1 mm(2); P < .001) and anterior chamber volume (97.6 vs 142.1 mm(3); P < .001) were smaller in eyes with narrow angles compared with those in eyes without narrow angles. After adjusting for age, sex, anterior chamber depth, axial length, and pupil size, smaller anterior chamber area (odds ratio, 53.2; 95% confidence interval, 27.1-104.5) and anterior chamber volume (odds ratio, 40.2; 95% confidence interval, 21.5-75.2) were significantly associated with the presence of narrow angles., Conclusion: Smaller anterior chamber area and anterior chamber volume were independently associated with narrow angles in Singaporeans, even after controlling for other known ocular risk factors.