Characteristics and prevalence of pterygium in small communities along the Solimões and Japurá rivers of the Brazilian Amazon Rainforest

Abstract

Purpose: To evaluate the prevalence and characteristics of pterygium in small communities along the Solimões and Japurá rivers, State of Amazonas, Brazil. Design: cross-sectional study. Methods: This study was carried out on populations of the Brazilian Amazon rainforest. Data were collected by two separate ophthalmologists in three expeditions, covering 55 local communities. A total number of 1295 patients were examined, of which 659 were over 18 years old. The patients diagnosed with pterygium answered a questionnaire addressing gender, age and outdoor activity. Pterygium lesion sizes were graded as grade 1 (lesion covers until limbus), grade 2 (lesion covers cornea by 2 mm), grade 3 (lesion surrounds the pupil) and grade 4 (lesion crosses the pupil). Results: Pterygium prevalence was 21.2% for the overall population and 41.1% in those over 18 years old. Patients between 40-50 years old were most affected by pterygium. Pterygium data distribution by gender showed that 57.8% were men. The majority of the patients diagnosed with pterygium was active outdoors (89.5%). Subjects affected in both eyes were 75.6%. Of the total population positive to pterygium the majority was grade 1 (44%) and 2 (48.7%). Most of the patients (85%) developed nasal pterygium. Conclusion: This study shows one of the highest prevalences of pterygium in the world, covering a Brazilian region never studied before.

Impact of Photochemical Reactions Induced by UV Light in Pterygium Lesions

“…Our results are similar to those obtained by F. Duman [30], based on a study group of 158 patients, who presented double pterygium in 5% of the cases, and also by M. Bikbov who studied a group of 138 patients [19]. Other studies conducted by Ribeiro and Bikbov also confirm the preference of this lesion for the nasal aspect [19,31]. This is mainly due to two different factors: environmental context that influences the distribution of UV radiation along the palpebral fissure, and Peripheral Light Focusing (PLF).…”

“…We did not perform a study of lesions' progression over a certain period of time. For our study, we report a variation of pterygium lesions' dimension between 1 mm to 8 mm, with an average of 3.83±1.47, a very high value compared to a study conducted by Mohammad-Salih PA in 2008 [34], where the lesion size varied between 0.25 and 6.50, as well as another study managed by LAM Ribeiro in 2011 [31], where 93% of all patients had lesions smaller than 2 mm. We observed a probability of pterygium formation similar for all age groups, indicating thus an independence degree for this parameter.…”

“…From our study lot, a number of 40 patients (representing 34% of the total number of patients) presented bilateral lesions. Bikbov reported a similar value -32.6% patients with bilateral pterygium [18], while two more studies on sample populations from Brazil [31] and Myanman [33] reported more extreme values: 75.6%, respectively 8%.…”

Prevalência de ametropias e oftalmopatias no quilombo São José da Serra - Valença - RJ

“…In 2010, Shiratori 37 found a prevalence of 8.12% for pterygium in the city of Botucatu/SP. Recently, while studying riverine populations in the Solimões and Japurá rivers in the Brazilian Amazon, Ribeiro 38 found some of the highest rates of pterygium in the world: 21.2% in the general population and 41.1% in adults older than 18 years. The 1.09% prevalence of pterygium found in Quilombo San José is low compared to other regions in Brazil and to the black rural population in Nigeria (8.2%).…”

Oftalmologia e atenção primária a saúde

“…Dez por cento dos estudos abordaram epidemiologia de doenças oculares. Destes, aproximadamente 85% foram realizados em instituições como hospitais e clínicas oftalmológicas e apenas 15% concluíram estudos epidemiológicos considerando dados de comunidades ou em âmbito populacional (1,2) . Quando se faz um estudo para estimar a distribuição estatística de doenças em hospital ou clínica especializada, ela pode sofrer viés, pois estes centros tendem a concentrar doentes mais graves.…”