Prevalence and associated factors for pterygium in Han and Mongolian adults: a cross-sectional study in inner Mongolian, China.

BACKGROUND: To investigate the prevalence of pterygium and associated factors in Han and Mongolian adults at four survey sites in Inner Mongolia, China. METHODS: We conducted a population-based, cross-sectional study as part of the China National Health Survey (CNHS). By means of a stratified sampling method, we finally included 2651 participants of 30 years of age or older from a total of 3468 eligible residents. Factors associated with pterygium were analysed by a univariate analysis and logistic regression models. RESULTS: The study population included 1910 Han and 741 Mongolian adults. The mean age ± standard deviation of the study cohort was 48.93 ± 11.06 years. The overall prevalence of pterygium was 6.4% (n = 169); 1.4% (n = 38) of the cases were bilateral and 4.8% (n = 128) were unilateral. The most common grade of pterygium was Grade 2. Based on the results of the univariate analysis, eleven factors were included in a multivariate analysis. The results indicated that age (P < 0.001), outdoor occupation (P = 0.026), and time spent in rural areas (P < 0.001) were significantly associated with pterygium. Sex and ethnicity were not identified as risk factors. CONCLUSIONS: Our results indicated that outdoor occupation, old age and more time spent in rural areas were risk factors for pterygium in Inner Mongolia. At the same time, town as a survey site (Hohhot and Tsining District) was a protective factor for pterygium. Ethnicity, gender, smoking, diabetes and high blood pressure are not associated with pterygium.

Prevalence and risk factors for pterygium: a cross-sectional study in Han and Manchu ethnic populations in Hebei, China.

AIMS: To investigate the prevalence, ethnic differences and associated risk factors for pterygium in Han and Manchu populations aged 40-79 years in Hebei province, China. DESIGN: Cross-sectional study, as a part of the China National Health Survey. SETTING: Hebei province, China. PARTICIPANTS: A multistage cluster sampling method with urbanisation level-based stratification was used to select participants for this study. A total of 4591 individuals over 40 years were recruited for this study. Inclusive criteria: (1) residents who had been living in Hebei for more than 1 year; (2) Han individuals with both parents being Han, or Manchu individuals with both parents being Manchu; (3) underwent ophthalmic examinations and (4) information in the questionnaire was complete. MAIN OUTCOME MEASURES: Multiple logistic regression analysis was used to evaluate the association between pterygium prevalence and factors of interest. RESULTS: A total of 3790 individuals (2351 Hans and 1439 Manchus) met the study criteria, of which 248 were diagnosed with pterygium (6.5%). There was no significant difference between the prevalence rates in Hans (6.2%) and Manchus (7.2%) (p=0.232). Multivariate analysis revealed that the risk factors for grade 2 or higher pterygium were increasing age (p<0.001) and rural residence (OR 1.83; 95% CI 1.11 to 3.02; p=0.018), while the protective factors include gender (female) (OR 0.58; 95% CI 0.37 to 0.88; p=0.011), cigarette smoking (OR 0.53; 95% CI 0.34 to 0.83; p=0.005) and myopia (OR 0.50; 95% CI 0.33 to 0.77; p=0.002). Premature menopause (OR 2.66; 95% CI 1.05 to 6.72; p=0.038) increased the risk of grade 2 or higher pterygium in females, while higher high-density lipoprotein (HDL) (OR 1.94; 95% CI 1.08 to 3.47; p=0.027) was a risk factor of grade 2 or higher pterygium in males. CONCLUSION: The overall prevalence of pterygium in Han and Manchu population in Hebei, China was approximately 6.1%. There were no differences in the prevalence of pterygium between Hans and Manchus, and the race was not a risk factor. This is the first study to report on the positive association between premature menopause and pterygium in females and between higher HDL levels and pterygium in males.

Comparison of Pterygium Recurrence Rates Among Different Races and Ethnicities After Primary Pterygium Excision by Surgeons in Training.

PURPOSE: To evaluate the impact of race and ethnicity, surgical technique, and level of surgeon training on recurrence rates after primary pterygium excision. METHODS: A retrospective review of patients who underwent primary pterygium excision at our academic institution was performed. The surgical technique-conjunctival autografting (CAG) or amniotic membrane grafting (AMG)-was chosen at the attending surgeon's discretion, and all surgeries were performed by surgeons in training. The primary outcome measure was pterygium recurrence, defined as regrowth of fibrovascular tissue onto a clear cornea in the region of previous pterygium removal. RESULTS: There was a significant difference in age at presentation between white (64.3 ± 11.4), Hispanic (50.0 ± 13.5), black (64.8 ± 14.5), and Asian (59.3 ± 9.2) patients (P < 0.001). Average time to recurrence was 4.4 ± 3.0 months and was similar between races (P = 0.98). There was a significant difference in recurrence rates between the white (13%), Hispanic (28%), black (33%), and Asian (0%) patients (P = 0.049). Over 12 months, a significant difference in cumulative proportion with recurrence after AMG versus CAG was observed in Hispanic (75% vs. 30%; P = 0.002) and black (100% vs. 42%; P = 0.001) patients. Sex, method of graft fixation (glue, suture, or both), and level of surgeon training showed no difference in pterygium recurrence (P > 0.05). CONCLUSIONS: Hispanic and black patients are more likely to experience pterygium recurrence after AMG than CAG. White patients are less likely than Hispanic or black patients to experience recurrence regardless of the surgical technique. To reduce the likelihood of recurrence, surgeons may consider race and ethnicity when selecting their operative technique.

Variations of pterygium prevalence by age, gender and geographic characteristics in China: A systematic review and meta-analysis.

BACKGROUND: Pterygium is a common chronic ophthalmic condition, which may result in significant visual morbidity or lead to blindness in extreme cases. The prevalence of pterygium in China has not been reported at the sub-national level. METHODS: In this study, we conducted a systematic review and meta-analysis to estimate the prevalence of pterygium in China. China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase and Medline were searched before September 2016. We performed a multilevel mixed-effect meta-regression based on the included studies, our results showed that age, gender and latitude were significantly associated with pterygium prevalence. Based on the final model, the age and gender-specific prevalence of pterygium in 31 Chinese provinces (except Hongkong, Macau and Taiwan) and the whole country was generated. RESULTS: In 2010, the overall prevalence of pterygium in Chinese people aged 15-84 years was 9.84% (95% CI: 6.72-14.14), and the number of pterygium cases in China was 108.65 million (95% CI: 74.23-156.13). CONCLUSIONS: In conclusion, the prevalence of pterygium in Chinese population in 2010 was estimated at both the national and provincial levels. The higher burden of pterygium across the country calls for efforts to advocate public health education encouraging people to take appropriate protective measures.

Ethnic Variations in Pterygium in a Rural Population in Southwestern China: The Yunnan Minority Eye Studies.

PURPOSE: To determine the prevalence and associations of pterygium in a multiethnic adult population in rural China and to examine potential ethnic differences Methods: A total of 6418 adults (2133 ethnic Bai, 2130 ethnic Yi, and 2155 ethnic Han) aged 50 years or older participated in the study. Anterior segment examination was performed without pupil dilation using a slit lamp. Pterygium was defined as a raised fleshy triangular fibrovascular tissue growth of the conjunctiva encroaching onto a clear cornea. RESULTS: Pterygium was least prevalent among adults of Yi ethnicity (29.5%) compared with Bai (39.0%, p < 0.001) or Han (39.5%, p < 0.001) ethnicities. Those of Bai ethnicity were most likely to be affected by severe pterygium (7.5%), while Yi were least likely to be affected (3.8%). Multivariate analysis revealed that increasing age (odds ratio, OR, 1.017), female sex (OR 1.53), lower educational level (OR 1.25), higher blood pressure levels (OR 1.002), and greater time spent outdoors per day (OR 1.09) were significantly associated with a higher prevalence of pterygium, while Yi ethnicity (OR 0.65, comparing Yi with Han) and wearing brimmed hats outdoors (OR 0.82) were protective factors. CONCLUSION: Ethnicity was significantly associated with prevalence of pterygium. Our findings may be applicable to many other countries located within the "pterygium belt" for health resource allocation among different ethnic groups.

Five-Year Incidence and Predictors for Pterygium in a Rural Community in China: The Yunnan Minority Eye Study.

PURPOSE: To determine the 5-year cumulative incidence of pterygium and its associated predictors in the Bai Chinese population in a rural community. METHODS: This population-based study included 2133 subjects aged 50 years or older in 2010 and was repeated in 2015 with 1520 subjects (71.3%) participating in the follow-up examination. Participants with pterygium in either eye in 2010 were excluded from the analysis related to incidence. Anterior segment examination was performed without pupil dilation using a slit lamp, and pterygium was defined as a raised fleshy triangular fibrovascular tissue growth of the conjunctiva encroaching onto the clear cornea. RESULTS: The 5-year cumulative incidence of pterygium was 6.8% [95% confidence interval (CI), 5.2-8.4] and was significantly higher in women compared with men (8.8% vs. 3.8%; P = 0.003). The age-specific incidence was 7.7%, 6.5%, and 5.6% in those aged 50-59, 60-69, 70 years, or older at the baseline, respectively. Outdoor occupation was the only predictor, which remained to be significantly associated with a higher incidence of pterygium in multivariate analysis (odds ratio = 2.52, 95% CI, 1.27-4.95). The predictive effect of outdoor occupation on incident pterygium was moderate with an area under the curve in the receiver operating characteristic analysis of 0.59 (95% CI, 0.53-0.66). CONCLUSIONS: The incidence of pterygium in this rural cohort was higher compared to a previous report in Chinese in urban areas. The findings are important for health policy makers to project future burden of pterygium and make proper decisions on health resource allocation.

Analysis of the GSTM1-null polymorphism in patients with pterygium from Goiânia, Goiás Brazil.

The first reports about pterygium date back to Hippocrates, and this disease still threatens vision health around the world. Pterygium is a formation of fibrous tissue consisting of highly vascularized epithelial and subepithelial tissue that grows excessively and with an abnormal shape on the cornea. Many physical and biological factors are associated with the pathogenesis of pterygium, including heat, dust, and other particles in the atmosphere, and immunological mechanisms, mechanisms involving extracellular matrix reorganization, growth factors, cytokines, apoptosis, and angiogenesis. The aim of this study was to further investigate the association between polymorphisms in GSTM1 and the formation of pterygium. We collected peripheral blood samples from 90 patients diagnosed with pterygium and from 23 subjects with-out the disease in order to perform molecular analysis of the GSTM1 gene. Subjects with one or two copies of the GSTM1 allele had a normal genotype while those without any copies of the allele had a null geno-type. The chi-square test or the Fisher exact test was performed in order to investigate possible associations between the molecular analysis and the risk of pterygium. A significant difference between the frequency of the GSTM1-null genotype in patient and control groups was identified. However, sub-group analysis found that the GSTM1-null genotype was statistically significant in men, but not in women, and in Caucasians, but not in Brown or Black groups. Furthermore, the GSTM1-null geno-type was not related to any of the risk factors analyzed: cases in family, occupational exposure, smoking, hypertension, and diabetes.

Pterygium in patients from Goiânia, Goiás, Brazil.

Pterygium is an inflammatory and degenerative ocular surface disease in which the conjunctiva on the cornea grows to form a fibrous tissue in the shape of a triangle. The disorder may be characterized by cell proliferation, inflammatory processes, fibrosis, angiogenesis, and destruction of the extracellular matrix. The anomaly is considered a degenerative eye disease and is erroneously confused with cataract. It displays similar features to those of tumors, such as local invasion, metaplasia of epithelial cells, presence of oncogenic viruses (human papilloma virus), inactivation of tumor suppressor genes (e.g., p53), and loss of heterozygosity. The treatment of pterygium is based on factors such as the evolution and progression of the disease, risk factors, symptoms, and patient age. Considerations about the best technique for the surgical removal of pterygium remain controversial, and complications and recurrence are very common. The development of new surgical techniques and adjuvant drugs is thus necessary. This study aims to analyze and compare the frequency of the GSTT1 genotypes in relation to pterygium through statistical analyzes in order to build a genotypic profile for the Replicon patients. The genotypic profile of the GSTT1-null polymorphism in Goiânia showed no significant difference when the frequency of the null genotype was compared between the control and experimental groups. The null genotype was more frequent in the population studied. Furthermore, the GSTT1 genotype was not related to the analyzed risk factors for pterygium, namely gender, ethnicity, family history, occupational exposure, smoking, hypertension, and diabetes.

Prevalence and racial differences in pterygium: a cross-sectional study in Han and Uygur adults in Xinjiang, China.

PURPOSE: To understand the prevalence and associated risk factors of pterygium in Han and Uygur population in Xinjiang, China and to assess the racial differences. METHODS: A cross-sectional study was conducted in two rural and three urban regions of Xinjiang. A multistage and stratified sampling method was used to select representative samples. Risk factors associated with pterygium were screened in logistic regression models. RESULTS: Among 4617 participants aged 30 years and older, 2452 were Han and 2165 were Uygur Nationality adults. The overall prevalence of pterygium was 11.95% (n = 546), with 4.27% (n = 197) were bilateral and 7.56% (n = 349) were unilateral. Multivariate analysis indicated that race, age, and rural residence were significantly associated with any pterygium (P < 0.001 for all). The prevalence of pterygium (P < 0.01) in Han subjects was higher than that of Uygur subjects. Both age and rural residence were associated with any pterygium in Han and Uygur. Low education level had significant positive association with pterygium in Han population (P < 0.001). CONCLUSIONS: Pterygium affects approximately one-ninth of Han and Uygur population. Compared with Uygur, Han ethnicity is a significant risk factor of pterygium. Our results indicated a higher prevalence of pterygium in rural areas of Xinjiang, China compared with urban cities. Age increase was also associated with presence of pterygium. Strategies are warranted to prevent the serious effects caused by pterygium.

Transcriptomic profiling explains racial disparities in pterygium patients treated with doxycycline.

PURPOSE: To understand the differential responses to doxycycline between Caucasian and Hispanic patients observed in a previous clinical trial. METHODS: Primary cultures were established using pterygia excised from male Caucasian (n = 3) and Hispanic (n = 6) patients. The response of these cells to doxycycline was tested in a toxicity assay. In addition, a complete transcriptome was obtained from the nine samples, and the results were analyzed using false discovery rate statistics. Results were confirmed by quantitative RT (qRT)-PCR and Western blotting for a limited set of genes. RESULTS: Caucasian pterygium cells underwent apoptosis upon exposure to doxycycline, whereas Hispanic cells survived the treatment. Transcriptomic analysis showed profound differences between cells of both ethnicities, even before treatment, implicating important cellular pathways such as the mitochondrial oxidative phosphorylation chain, the proteasome, and the components of the extracellular matrix. Following exposure to doxycycline, there was a significant increase in proapoptotic proteins, regulators of the cell cycle, and components of the mitochondrial membrane in Caucasian cells but not in their Hispanic counterparts. There was a good correlation between data obtained by ultrasequencing and those generated by qRT-PCR or Western blotting. CONCLUSIONS: The lack of response to doxycycline observed in Hispanic pterygium patients in a previous clinical trial can be explained by the genetic protection afforded to the cells in this ethnic background against apoptosis and cell death. New therapeutic options must be devised for these patients.

Prevalence of and risk factors for pterygia in a rural Northern Chinese population.

PURPOSE: To determine the prevalence of and associated risk factors for pterygia development in a high-latitude-dwelling Northern Chinese population. METHODS: A prospective population-based survey was conducted between November 2008 and July 2009. A stratified, clustered, randomized sampling procedure was used to select 8445 subjects, aged ≥18 years, all with diagnosed, graded pterygia. Risk factors associated with the occurrence of pterygia were evaluated according to logistic regression models. RESULTS: A total of 8445 residents (aged 18-94 years) from the Heilongjiang Province, China, participated in the study. Of these, 208 (2.5%) had at least one diagnosed pterygium. The prevalence of bilateral pterygia was 1.2% (95% confidence interval, CI, 1.0-1.4%). According to multivariable analysis, pterygia were significantly more likely to occur in persons aged 70-94 years than in those aged 18-39 years (odds ratio, OR, 29.0, 95% CI 13.6-61.6, p < 0.01). Pterygia were significantly associated with male sex (OR 1.9, 95% CI 1.4-2.6, p < 0.01) and outdoor work (OR 1.8, 95% CI 1.2-2.6, p < 0.01). Multivariable analysis indicated that pterygia were not associated with smoking status (OR 1.0, 95% CI 0.8-1.4) or alcohol intake (OR 1.0, 95% CI 0.7-1.4, p > 0.05). CONCLUSIONS: This study details the occurrence of and risk factors for pterygia in a Chinese population residing in a rural, high-latitude, cold-climate area of Northern China. The primary risk factors for pterygia were age, male sex, and outdoor work.

Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi-ethnic patients in the Malay Peninsula.

PURPOSE: The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula. METHODS: DNA was extracted from 45 specimens of freshly obtained primary and recurrent pterygia from patients and from 11 normal conjunctival swabs from volunteers with no ocular surface lesion as control. The presence of HPV DNA was detected by nested PCR. PCR-positive samples were subjected to DNA sequencing to determine the HPV genotypes. Real-time PCR with HPV16 and HPV18 type-specific TaqMan probes was employed to determine the viral DNA copy number. RESULTS: Of 45 pterygia samples with acceptable DNA quality, 29 (64.4%) were positive for HPV DNA, whereas all the normal conjunctiva swabs were HPV negative. Type 18 was the most prevalent (41.4% of positive samples) genotype followed by type 16 (27.6%). There was one case each of the less common HPV58 and HPV59. Seven of the samples harboured mixed infections of both HPV16 and HPV18. All the four known recurrent pterygia samples were HPV-positive, whereas the sole early-stage pterygium sample in the study was HPV-negative. There was no significant association between HPV-positive status with gender or age. A high proportion of patients from the Indian ethnic group (five of six) were HPV-positive, whereas the Malay patients were found to have higher HPV positivity than the Chinese. The viral load of HPV18 samples ranged between 2 × 10(2) and 3 × 10(4) copies per µg, whereas the viral load of HPV16 specimen was 4 × 10(1) to 10(2) copies per µg. CONCLUSION: This report describes for the first time the quantitative measurement of HPV viral DNA for pterygium samples. The high prevalence of oncogenic HPVs in our samples suggests a possible role for HPV in the pathogenesis of pterygia. Moreover, the relatively low HPV viral load is concordant with the premalignant nature of this ocular condition.

Chronic inflammatory cells and damaged limbal cells in pterygium.

BACKGROUND: Chronic inflammation in pterygium occurrence has not been explained. Whether damaged limbal basal epithelial cells are associated with pterygium occurrence in black Africans is not clear. OBJECTIVE: To explain chronic inflammation in pterygium, and to clarify whether damaged limbal basal epithelial cells were associated with pterygium occurrence in black Africans. METHODS: Chronic inflammatory changes and damaged limbal basal epithelial cells were assessed in 59 samples. RESULTS: Chronic inflammatory cells were present in 59 pterygia. Inflammatory cell count in 5 (27.8%) of 18 small pterygia was >200 (high) while in 22 (53.7%) of 41 large growths was <200 (low); p = 0.25. The proportion of pterygia with high counts tended to increase with pterygium extent. Twenty (33.9%) of 59 pterygia recurred after surgery. Ten (50%) of 20 samples had high cell counts and 10 (50%), low counts; p = 0.40. P53 expression was detected in 11 (18.6%) of 59 pterygium samples and 5 (71.4%) of 7 controls; p = 0.007. MMP 1 staining was present in 14 (23.7%) of 59 sections and 5 (71.4%) of 7 controls; p = 0.02. MMP2 in 16 (27.1%) cases and 5 (71.4%) controls; p = 0.03. MMP3 was overexpressed in 16 (27.1%) of 59 cases and 5 (71.4%) controls; p = 0.03. CONCLUSIONS: Mild chronic inflammation has a tendency to be more frequent than severe inflammation in pterygia. It is clear that damaged limbal basal epithelial cells are unlikely to be related to pterygium occurrence.

The prevalence of and risk factors associated with pterygium in a rural adult Chinese population: the Handan Eye Study.

PURPOSE: To describe the prevalence and risk factors for pterygium in a rural adult Chinese population. METHODS: A total of 7557 people aged 30 years and over were randomly selected from 13 villages in a rural county, Yongnian, within Handan district, Hebei Province of China. All eligible subjects were invited to undergo a comprehensive eye examination. A slit-lamp was used to examine the anterior segment for evidence of pterygium. Pterygium was graded for severity (G1 to G3) by visibility of episcleral vessels. RESULTS: Of 6685 participants (88.5% of 7557) included in this study, pterygium was present in 401 (6.0%). Using direct standardization to the 2000 China population census for rural residents, the prevalence of pterygium was 7.1% (95% confidence interval [CI], 6.5-7.8%) among subjects aged 40+ years, and 4.8% (95% CI 4.3-5.3%) when including those aged 30-39 years. Pterygium was more common in men than in women (age-adjusted odds ratio [OR] 2.0, 95% CI 1.4-2.8). Prevalence increased with age (OR 1.8, 95% CI 1.6-2.1 per decade increase in age). Current smoking appeared to be protective (OR 0.5, 95% CI 0.4-0.7). Of eyes with any pterygium, 4.6% (95% CI 1.9-7.3%) had low vision. CONCLUSION: Approximately one in ten adults had pterygium in this rural Chinese population. Age and male sex were positively, and current smoking negatively associated with the prevalence of pterygium.

Prevalence of and risk factors for pterygium in rural adult chinese populations of the Bai nationality in Dali: the Yunnan Minority Eye Study.

PURPOSE: The purpose of the study was to describe the prevalence, severity, and associated risk factors for pterygium in a population-based sample of rural residents of the Bai minority population in rural Dali, China. METHODS: A population-based survey of Chinese Bai Nationality aged ≥50 years from randomly selected block groups in southwestern China was conducted. A clinical examination by experienced ophthalmologists was carried out, and the presence of pterygium was diagnosed at the examination. Pterygium was graded clinically by slit lamp examination. Questionnaires were conducted on risk factors. RESULTS: From a total of 2742 eligible subjects, 2133 (77.8%) were examined. The prevalence of pterygium was high (overall 39.0% [95% confidence interval (CI) 37.0-41.0]). Women had a higher rate than men (27.3% vs. 11.7%, respectively). In multivariate analysis, pterygium was independently associated with increasing age (odds ratio [OR] 1.55 [95% CI 1.24-1.93], 1.47 [95% CI 1.13-1.91], and 1.79 [95% CI 1.17-2.73], respectively, for persons 60-69 years, 70-79 years, and 80 years and older compared with 50-59 years), female sex (OR 1.42 [95% CI 1.08-1.88]), lack of formal education (OR 1.26 [95% CI 1.03-1.56]), and presence of outdoor work (OR 1.51 [95% CI 1.10-1.92]). Height, weight, hypertension, diabetes, smoking, and alcohol use history were not associated with pterygium. CONCLUSIONS: The prevalence of pterygium in Dali is 39.0% among Chinese Bai aged 50 years and older. Independent associations with increasing age (>59 years), female sex, lack of education, and occupations linked to outdoor work suggest a multifactorial cause of this condition.

Traditional eye medication and pterygium occurrence in Limpopo Province.

BACKGROUND: The relative importance of environmental and hereditary factors in the occurrence of pterygium in African blacks has not been reported. AIM: To investigate the relative significance of factors associated with pterygium occurrence. METHODS: This was a prospective case-controlled study where 150 pterygium patients and 150 controls participated. Interviews were conducted, eyes examined and multivariate analysis done. The families of 51 pterygium cases and 50 controls were examined for presence of pterygium. RESULTS: Of 150 cases and 150 controls, 79 (52.6%) and 60 (40%) used traditional eye drops (odds ratio (OR) 2.03; p=0.009. Ten cases (6.6%) and 26 controls (17.3%) had unstable tear film (OR 0.30; p=0.007. Forty-six cases (30.6%) and 15 controls (10%) reported a positive family history (OR 3.93; p<0.001). Groups of 3 - 5 pterygium cases in a household occurred in 36 of 51 pterygium families (70.5%) v. 1 of 50 controls (2%). CONCLUSIONS: Pterygium occurrence was associated with the use of traditional eye drops, a positive family history and having groups of diagnosed pterygium-affected relatives. However, unstable tear film seemed protective against pterygium occurrence.

Prevalence of and racial differences in pterygium: a multiethnic population study in Asians.

PURPOSE: To describe the prevalence and risk factors of pterygium in a multiethnic Asian population and to examine racial differences. DESIGN: Population-based study in Singapore, located 1° north of the equator. PARTICIPANTS: Data were analyzed from 8906 participants from 3 population-based studies of Malays, Indians, and Chinese persons 40 years of age and older conducted between 2004 and 2011. METHODS: Standardized slit-lamp examinations were performed by trained study ophthalmologists to examine the anterior segment for evidence of pterygium. Every subject underwent standardized systemic and ocular examinations, interviewer-administered questionnaires, and blood investigations for risk factor assessment. Regression and principle component analysis models were constructed to study the relationship of race and other factors to pterygium. MAIN OUTCOME MEASURES: Any pterygium and severe (grade 3 or opaque) pterygium. RESULTS: The overall prevalence of any pterygium was 10.1% (n = 900), of which severe pterygium was seen in 1.6% (n = 142). The prevalence of any pterygium was more common in Malays (15.5%) than Chinese (7.0%; P<0.001) or Indians (7.0%; P<0.001). Multivariate analysis revealed increasing age (P<0.001), male gender (P<0.001), Malay race (P<0.001), and having a poorer education level (P<0.001) as significant factors for any pterygium. Race contributed significantly to presence of any pterygium (41%; P<0.001) or presence in both eyes (33%; P<0.001) compared with other risk factors. Severe pterygium was associated with outdoor occupation (P = 0.02), but race was not a significant risk factor in multivariate analysis. CONCLUSIONS: This population-based study in Asian persons of different races living in the same geographical location at the equator indicated that race is a significant risk factor for pterygium, with Malays having higher prevalence than Indians and Chinese, while controlling for other risk factors.

Characteristics and prevalence of pterygium in small communities along the Solimões and Japurá rivers of the Brazilian Amazon Rainforest / Características e prevalência do pterígio em comunidades ribeirinhas dos Rios Solimões e Japurá localizados na Amazônia Brasileira

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 percent for the overall population and 41.1 percent 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 percent were men. The majority of the patients diagnosed with pterygium was active outdoors (89.5 percent). Subjects affected in both eyes were 75.6 percent. Of the total population positive to pterygium the majority was grade 1 (44 percent) and 2 (48.7 percent). Most of the patients (85 percent) developed nasal pterygium. CONCLUSION: This study shows one of the highest prevalences of pterygium in the world, covering a Brazilian region never studied before.

OBJETIVO: Avaliar a prevalência e as características do pterígio em comunidades ribeirinhas dos rios Solimões e Japurá, estado do Amazonas, Brasil. MÉTODOS: Foi realizado um estudo observacional, em comunidades ribeirinhas dos rios Solimões e Japurá. Os dados foram coletados por dois avaliadores em três expedições médico oftalmológicas, num período de 9 meses, que abrangeram 55 comunidades ribeirinhas, totalizando 1295 pacientes examinados, sendo 659 maiores de 18 anos. Os portadores de pterígio foram analisados através de um questionário abrangendo sexo, idade e atividade laborativa ao sol ou não. O tamanho da lesão foi quantificado em graus. RESULTADOS: A prevalência do pterígio na população geral foi de 21.2 por cento. A prevalência entre os maiores de 18 anos foi de 41.1 por cento. A faixa etária mais acometida foi a de 41 a 50 anos. Dos portadores, 42.2 por cento eram do sexo feminino e 57.8 por cento do sexo masculino. 89.5 por cento dos pacientes acometidos pela lesão trabalhavam ao ar livre. Dos portadores, 75.6 por cento apresentavam acometimento de ambos os olhos. Dos pacientes acometidos, 48.7 por cento possuíam pterígio grau 2, 44.0 por cento apresentavam a lesão de grau 1, 5.4 por cento de grau 3 e 1.8 por cento de grau 4. Dos olhos acometidos, 85.0 por cento apresentavam somente pterígio nasal, 2.9 por cento apresentavam somente pterígio temporal e 14.5 por cento apresentavam pterígio temporal e nasal. CONCLUSÃO: Nosso estudo, nos rios Solimões e Japurá, revelou a existência de uma das maiores taxas de pterígio do mundo, em uma região que nunca havia sido avaliada.