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Marcia Regina Kimie Higashi Mitsuhiro, Sergio Munoz, Adriana Berezovsky, Cristina Cunha, Joao M Furtado, Galton Vasconcelos, Marcos Jacob Cohen, Jacob Moyses Cohen, Rubens Belfort Jr, Solange Rios Salomao; Characterization of Pterygium as Primary Cause of Visual Impairment/Blindness in Older Adults from Urban Areas of Parintins: The Brazilian Amazon Region Eye Survey. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6205.
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© ARVO (1962-2015); The Authors (2016-present)
Ultraviolet (UV) radiation is the most commonly reported risk factor associated to the occurrence of pterygium. Parintins is located 02o37’42”S latitude and 56o44’09’’W longitude in the center of the Brazilian Amazon region, an equatorial territory with high exposure to UV rays. The purpose of this study is to characterize visually impaired/blind eyes attributable to pterygium in older adults from urban Parintins City, Brazil.
The Brazilian Amazon Region Eye Survey (BARES) is an ongoing population-based cross-sectional study to determine prevalence and causes of visual impairment/blindness of residents of urban and rural areas, aged 45 years and older. Eligible participants from urban areas were invited for ophthalmic assessment including presenting (PVA), best-corrected visual acuity (BCVA), anterior segment evaluation by slit-lamp, refraction and fundoscopy. Eyes with pterygium as the principal cause of BCVA ≤20/40 were photographed and the size of the lesion was calculated. Thickness of the lesion was measured in the most prominent section with anterior segment spectral-domain optical coherence tomography (ASSD-OCT). Correlations between size and thickness of the lesions with best-corrected visual acuity, gender, refractive errors and schooling were performed.
In a cohort of 579 participants, pterygium was detected in 322 (55.5%), bilaterally occurring in 201. Out of these, 18 subjects (13 females) with 22 eyes (14 unilateral and 4 bilateral) had visual impairment caused by pterygium (5.6%). Nasal lesions only were present in 20 eyes, temporal lesions only in 2 eyes and both nasal and temporal lesions in 10 eyes. Lesion sizes ranged from 0.15 to 0.64 (mean= 0.36±0.13) of corneal diameter. Pterygium thickness ranged from 222 to 736 mm (mean=389±104 mm). Visual impairment (BCVA <20/40) was found in 19 eyes and blindness (BCVA <20/200) was present in 3 eyes. No correlations were found between lesion size/thickness with BCVA, gender, refractive error and schooling.
In this cohort of this at-risk population, pterygium was highly prevalent and caused visual impairment/blindness in 3.1% of participants. Lesion size wasn’t a good predictor of visual impairment as well as thickness. Further studies with larger sample sizes are needed to better understand the visual deficit associated with this disorder.
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