ABSTRACT
BACKGROUND: A hospital-based study was conducted in 2007 in Oman to determine the validity of frequency doubling perimetry (FDP). The authors have compared the ability of FDP to detect glaucoma among patients with and without diabetes. METHODS: This was a validity study of the screening procedure. An ophthalmologist and an optometrist examined Omani persons >30 years of age with and without diabetes. They determined glaucomatous field changes by using FDP. The glaucoma specialist labeled the eye and the person as suffering from glaucoma if two criteria were present: (1) optic cup disc and other retinal changes suggestive of glaucoma and (2) field changes on automated perimeter suggestive of glaucoma. Ocular pressure was measured with a Tono-Pen (Medtronic Ophthalmics, Jacksonville, FL). We calculated the validity of glaucoma screening by FDP among persons both with diabetes and without diabetes. RESULTS: We examined 111 eyes of 56 Omani patients (55 eyes of 28 patients with diabetes and 56 eyes of 28 persons without diabetes). Two persons had a history of glaucoma in both eyes. Glaucoma screening by FDP detected five eyes (two eyes of patients with diabetes and three eyes of persons without diabetes) with glaucoma. The specificity of glaucoma screening among those with and without diabetes was 97.4% and 97.3%, respectively. The sensitivity was 6% and 11%, respectively, in these two groups. CONCLUSIONS: Validity of glaucoma screening by FDP is not different among those with and without diabetes. In countries with high rates of diabetes, FDP could be used as a first-level screening tool for glaucoma.
Subject(s)
Diabetes Mellitus/physiopathology , Glaucoma/diagnosis , Visual Field Tests/methods , Adult , Diabetic Retinopathy/diagnosis , Diabetic Retinopathy/pathology , Female , Humans , Male , Mass Screening , Middle Aged , Oman , Optic Disk/pathology , Reproducibility of Results , Retina/pathologyABSTRACT
BACKGROUND: A prevalence survey of blindness and low vision was conducted in Oman in 2005. Here, we present the prevalence and determinants of blindness and low vision among the population >or= 40 years of age. The results are then compared with those of the survey in 1997 and the changes following the 'VISION 2020' initiatives are assessed. METHODS: The survey covered 24 randomly selected clusters (75 houses in each). Teams assessed the distance vision of subjects while wearing glasses. The ophthalmologists examined the anterior segment and fundus to determine the causes of disability. The visual field was tested in those suspected of glaucoma. The prevalence rates of blindness (< 3/60 on presentation), legal blindness (< 6/60) and low vision (< 6/18) were calculated. The data from the 1997 survey was then analyzed to obtain similar rates in the population >or= 40 years of age. RESULTS: The prevalence of blindness was 8.25% (95% CI 7.14-9.36) in the >or= 40 year-old population in 2005. The rate would be 6.95% (95% CI 5.92-7.98) if blindness were defined as vision with best possible correction. The prevalence of legal blindness and low vision were 12% and 45.12%, respectively. In the 1997 survey, the prevalence of blindness in same age group was 7.23% (95% CI 5.91-8.55). Between the two surveys, the prevalence of blindness due to corneal pathology declined from 1.9% to 1.1% but that of blindness due to unoperated cataract increased from 1.8% to 2.3%. CONCLUSIONS: The rate of disability has declined but the number of blind people has increased in Oman. The causes of blindness have changed from communicable/avoidable eye diseases to non-curable/chronic eye diseases, and the number with visual disabilities has increased. An increasing number of operations for cataract and improvements in the care for glaucoma and diabetic retinopathy are recommended.
