Conjunctival Ultraviolet Autofluorescence Area Research Articles

Could Children's Myopization Have Been Avoided during the Pandemic Confinement? The Conjunctival Ultraviolet Autofluorescence (CUVAF) Biomarker as an Answer.

The objective of this study was to evaluate the association of the presence of conjunctival ultraviolet autofluorescence (CUVAF) with the level and progression of myopia and the impact of reduced sunlight exposure during the COVID-19 pandemic confinement (PC). A retrospective observational study was carried out using three cohorts, children (9-17 years old), young adults (18-25 years old), and adults (>40 years old) with myopia (≤0.75D) and at least three annual eye examinations (before and after PC). All participants underwent an automatic objective refraction and CUVAF area analysis. All the participants filled out a questionnaire regarding lifestyle and myopia history. The 298 recruited participants showed that during the PC, children's and young adults' myopia progression rate increased on average by -0.50 and -0.30 D/year, respectively, compared with the pre-pandemic level (p < 0.0001 and p < 0.01). A significantly greater progression was observed in those with low baseline myopia compared to those with moderate or high myopia (p < 0.01). CUVAF shows its protective effect associated with outdoor activity (OA) with regard to the age of onset of myopia and mean diopters (p < 0.01). In fact, although there were no differences in the increase in diopters between children with and without CUVAF during the PC, those who had CUVAF started with lower gains (-0.3 D/year) compared to those who did not (-0.5 D/year; p < 0.05). The myopia treatments (atropine drops, Ortho-K, and MiSight® contact lenses) showed a reduction effect in myopic progression rate post-PC in comparison with non-treated children (p < 0.0001, p < 0.0001 and p < 0.01, respectively). The strict restriction of OA during PC led to the rate of myopia progression doubling among children and young adults. This progression occurred mainly in children with previously low myopia, and CUVAF, as a biomarker of OA, reflects its potential to provide benefits in the form of recommended behavioral changes to protect against the development of myopia.

Conjunctival ultraviolet autofluorescence as a biomarker of outdoor exposure in myopia: a systematic review and meta-analysis

Outdoor exposure is considered the primary modifiable risk factor in preventing the development of myopia. This effect is thought to be attributed to the light-induced synthesis and release of dopamine in the retina. However, until recent years, there was no objective quantifiable method available to measure the association between time spent outdoors and myopia. It is only recently that the conjunctival ultraviolet autofluorescence (CUVAF) area, serving as a biomarker for sun exposure, has begun to be utilized in numerous studies. To provide a comprehensive summary of the relevant evidence pertaining to the association between the CUVAF area and myopia across different geographic regions and age groups, a systematic review and meta-analysis were conducted. The search encompassed multiple databases, including MEDLINE, SCIENCE DIRECT, GOOGLE SCHOLAR, WEB OF SCIENCE, and SCOPUS, and utilized specific search terms such as "conjunctival ultraviolet autofluorescence", "CUVAF", "UVAF", "objective marker of ocular sun exposure", "myopia", "degenerative myopia", and "high myopia". The bibliographic research included papers published between the years 2006 and 2022. A total of 4051 records were initially identified, and after duplicates were removed, 49 articles underwent full-text review. Nine articles were included in the systematic review. These studies covered myopia and outdoor exposure across different regions (Australia, Europe and India) with a total population of 3615 individuals. They found that myopes generally had smaller CUVAF areas compared to non-myopes. The meta-analysis confirmed this, revealing statistically smaller CUVAF areas in myopic patients, with a mean difference of − 3.30 mm2 (95% CI − 5.53; − 1.06). Additionally, some studies showed a positive correlation between more outdoor exposure and larger CUVAF areas. In terms of outdoor exposure time, myopic patients reported less time outdoors than non-myopic individuals, with a mean difference of − 3.38 h/week (95% CI − 4.66; − 2.09). Overall, these findings highlight the connection between outdoor exposure, CUVAF area and myopia, with regional variations playing a significant role. The results of this meta-analysis validate CUVAF as a quantitative method to objectively measure outdoor exposure in relation with myopia development.

Prevalence and Risk Factors of Myopia in Young Adults: Review of Findings From the Raine Study.

Myopia tends to develop and progress fastest during childhood, and the age of stabilization has been reported to be 15–16 years old. Thus, most studies on myopia have centered on children. Data on the refractive error profile in young adulthood — a time in life when myopia is thought to have stabilized and refractive error is unaffected by age-related pathology such as cataract — are limited. The Raine Study has been following a community-based cohort of young adults representative of the general Western Australia population since their prenatal periods in 1989–1991, with eye examinations performed when participants were 20 and 28 years old. At 20 years old, prevalence of myopia in the cohort was 25.8%. Using long-term trajectory of serum vitamin D levels and conjunctival ultraviolet autofluorescence (CUVAF) area to objectively quantify sun exposure, the Raine Study confirmed a negative relationship between time spent outdoors and myopia prevalence. However, prospective studies are required to determine the amount of CUVAF area or serum vitamin D levels associated with time duration. Combining data from the Raine Study and several other cohorts, Mendelian randomization studies have confirmed a link between myopia and a genetic predisposition toward higher education. Several novel potential associations of myopia or ocular biometry were investigated, including fetal growth trajectory, which was found to be significantly associated with corneal curvature at 20 years. By age 28, myopia prevalence had increased to 33.2%. Between 20 and 28 years old, myopia progressed and axial length elongated, on average, by −0.041D/year and 0.02 mm/year, respectively. Smaller CUVAF area at follow-up, female sex, and parental myopia were significant risk factors for myopia incidence and progression between 20 and 28 years. Given the limited research in young adults, further investigations are warranted to confirm the Raine Study findings, as well as identify novel genetic or environmental factors of myopia incidence and progression in this age group.

Myopia, Melatonin and Conjunctival Ultraviolet Autofluorescence: A Comparative Cross-sectional Study in Indian Myopes

ABSTRACT Purpose: To explore the role of outdoor light exposure by estimating ocular sun exposure measured by Conjunctival Ultraviolet Autofluorescence (CUVAF) imaging and serum melatonin levels in myopes and non-myopes. Materials & Methods: Age and sex matched emmetropes and myopes (60 each) aged 10–25 years participated. Those with a history of ocular surgery or any ocular or systemic co-morbidity were excluded. Socio-demographic parameters, sun exposure questionnaires, indoor and outdoor activity profile, morning serum melatonin levels, sleep pattern, degree of myopia, ocular biometry and area of CUVAF on ultraviolet photography were noted and analyzed. Results: Mean age of myopes (18 ± 4.5 years) and emmetropes (18.5 ± 4 years) was similar (P = .523). Serum melatonin levels were significantly higher (P = .001) among myopes (89.45 pg/ml) as compared to emmetropes (52.83 pg/ml). Lifetime sun exposure was significantly lower in myopes than emmetropes (P = .0003). Area of CUVAF was inversely related to degree of myopia (P < .0001). Day time sleepiness was greater in myopes (51.7%) than emmetropes (15%) (P < .0001). There was a positive correlation between serum melatonin levels and axial length among myopes (correlation coefficient = 0.27; P = .03). Age and gender had no association with serum melatonin levels. Conclusion: This study demonstrates an inverse relationship between serum melatonin levels and degree of CUVAF in myopes. A novel link between serum melatonin, axial length and outdoor sun exposure is highlighted in the current study.

Role of Conjunctival Ultraviolet Autofluorescence in Ocular Surface Squamous Neoplasia

Objective: To evaluate the adjunctive role of conjunctival autofluorescence in the management of ocular surface squamous neoplasia (OSSN). Materials and Methods: Seventeen patients with clinically diagnosed OSSN were included. Morphological characteristics, type of OSSN, and autofluorescence photographs of the lesion were captured. Presence and area of conjunctival ultraviolet autofluorescence (CUVAF) were the main outcome measures. Results: Overall, 17 patients with 15 (88%) primary and 2 (12%) recurrent OSSN were included. Common locations were temporal (n = 10), nasal (n = 5), and diffuse variety (n = 2). Morphologically, there were 4 (22.2%) nodular, 4 (22.2%) leucoplakic, 3 (16.7%) gelatinous, and 1 (5.5%) each of papillary, nodulo-ulcerative, and diffuse variety. Mixed morphology was present in 4 eyes (22.2%). Sixteen of 18 eyes (88.9%) with OSSN displayed autofluorescence on CUVAF images. The mean area of CUVAF was 15.82 mm² (10.77–19.59 mm²). Autofluorescence was reported in 8 eyes (44.4%) which had negative reports on impression cytology. Conclusions: Conjunctival autofluorescence was seen in the majority of cases with OSSN, in spite of negative cytology reports. Our study demonstrates that CUVAF may serve as an effective ancillary, non-invasive, and resource-friendly tool for supplementing the clinical diagnosis of OSSN, especially in diffuse and recurrent lesions that are not amenable to surgical intervention.

Conjunctival Ultraviolet Autofluorescence as a Measure of Riboflavin and Ultraviolet and Accelerated Cross-Linking Exposure in Keratoconic Patients.

Purpose: The study was performed to analyze the prevalence of the conjunctival ultraviolet autofluorescence (CUVAF) area in keratoconic eyes and changes caused by UVA-irradiation as a component of accelerated corneal cross-linking (aCXL). Methods: The study group involved 20 keratoconic patients subjected to aCXL surgery in one eye. The comparative group consisted of 111 age- and sex-matched patients with healthy corneas. The images of the anterior segment in both patient groups were taken using a Coroneo camera. In the study group the photos were taken before and immediately after the surgery, and 7 and 30 days following the procedure. Results: Nasal and temporal autofluorescence area (AN+T) were significantly smaller in a keratoconic patients group compared to control group (p = 0.0001). Patients with the third stage of keratoconus had significantly higher AN+T (p = 0.0277) compared with individuals with lower stage keratoconus. No statistically significant CUVAF changes were observed after the aCXL procedure. In keratoconic patients with primary CUVAF undergoing aCXL, a temporary fast enlargement of the autofluorescence area was observed. Conclusions: The eyes undergoing the aCXL procedure showed no difference in the size of the CUVAF area but such patients should be in strict follow-up in order to reveal UV-related ocular surface diseases.

Has the Sun Protection Campaign in Australia Reduced the Need for Pterygium Surgery Nationally?

ABSTRACT Background The Slip! Slop! Slap! Sunsmart safety campaign was an Australian initiative implemented in the 1980s. To assess this campaign’s effect on pterygium, we examined the rate of pterygium surgery across Australia and described the prevalence and associations of pterygium in Perth, Australia’s sunniest capital city. Methods The rate of pterygium surgery was examined using Australian Medicare data. A cross-sectional analysis of the Generation 1 (Gen1) cohort of the Raine Study was performed to investigate the prevalence of pterygium in Perth. We investigated the association between pterygium and conjunctival ultraviolet autofluorescence (CUVAF) area, an objective biomarker of sun exposure, and demographics and health variables derived from a detailed questionnaire. Results Between 1994 and 2017, the rate of Medicare funded pterygium surgery in Western Australia fell 11%, well below the national average decline of 47%. Of the 1049 Gen1 Raine Study participants, 994 (571 females; mean age 56.7 years, range = 40.9–81.7) were included in the analysis. The lifetime prevalence of pterygium was 8.4% (n = 83). A higher prevalence of pterygium was associated with outdoor occupation (p-trend = 0.007), male sex (p-trend 0.01) and increasing CUVAF area (p-value <0.001). Conclusions The effect of Australia’s Slip! Slop! Slap! Sunsmart safety campaign on pterygium been mixed. Since 1994, the rate of private pterygium surgery has declined significantly in all Australian states except Western Australia. Perth, Western Australia, has the highest pterygium prevalence of any mainland-Australian cohort. Higher CUVAF area, male sex, and outdoor occupation were associated with an increased risk of pterygium.

Conjunctival ultraviolet autofluorescence area, but not intensity, is associated with myopia

BackgroundConjunctival ultraviolet autofluorescence (CUVAF) has been used as a biomarker of time spent outdoors. Smaller CUVAF area is associated with myopia in southern hemisphere cohorts. Further research is required to determine if this association is replicated in northern latitudes and whether average CUVAF intensity is a valuable metric. This prospective study explored the association between myopia, CUVAF (area and intensity) and additional indicators of sun exposure (vitamin D3 and self‐reported sun exposure preferences) across seasons at a location of 55° north.MethodsYoung adults (age 18–20) provided blood samples biannually (March/April and September/October) over an 18‐month period (four phases) for the assessment of 25‐hydroxyvitamin D (25(OH)D3) concentrations (liquid chromatography‐tandem mass spectrometry). CUVAF (total area, average intensity) and self‐reported sun exposure preferences were recorded at each phase. Axial length and corneal radius were measured. Refractive error was measured by autorefractor and spherical equivalent refraction used to classify participants into refractive groups: myopic (spherical equivalent refraction ≤ −0.50 DS) or non‐myopic.ResultsFifty‐four participants (24 myopes, 30 non‐myopes) participated. CUVAF area was negatively associated with the presence of myopia (odds ratio = 0.94, 95 per cent confidence interval = 0.90–0.98, p = 0.002). Myopes = 4.5 mm2 (interquartile range [IQR] 0.95–6.4 mm2), non‐myopes = 7.0 mm2 (IQR = 2.0–10.7 mm2). No significant association was found between CUVAF intensity and refractive group (p = 0.17). There was no significant association between sun exposure preferences or serum concentration of 25(OH)D3 and refractive status (all p ≥ 0.21). CUVAF measures were not associated with ocular biometry measures (all p ≥ 0.084). CUVAF area was unaffected by season (all p ≥ 0.45) and variations in CUVAF area over the study period did not exceed the repeatability of the measurement technique.ConclusionMyopia was associated with smaller areas of CUVAF indicative of less cumulative ultraviolet‐B exposure. These findings suggest that CUVAF measures are a useful, non‐invasive biomarker of the time spent outdoors in adults in northern hemisphere populations.

Photodamage of the anterior eye surface from UV radiation. Adequate methods of protection

Introduction: Ultraviolet (UV) light is electromagnetic radiation with a wavelength from 400 nm to 10 nm, occupying the light spectrum between the visible light and the X-rays. Essential for the normal development of the body in moderate, excessive exposure to UV radiation can lead to many diseases. Absorption of UV radiation from the eye is in correlation with the wavelength, and most of it is absorbed by the cornea and the conjunctiva. To objectively measure the UV radiation reaching the eye, the method of conjunctival autofluorescence is developed. Purpose: To present our first data and impressions of the sun protection habits and conjunctival ultraviolet autofluorescence (UVAF) of a randomly selected target group. Materials and Methods: A prospective, randomized study, including photographs of 123 subjects (246 eyes) and 200 questionnaires. Results: Results are based on the study of 123 subjects (246 eyes). Each eye is documented in three pictures - eye in first position, temporal gaze (documenting nasal part of the limbus) and nasal gaze (documenting temporal part of the limbus). Results were analyzed with specialized software [14], [15] and show that 83 persons (67.48%) have conjunctival autofluorescence, as women prevail (women n=47 persons, men n=36 persons). The participants in the study were aged between 5 and 88 years (average age=39). The area of conjunctival UVAF tends to increase with (Norfolk Islands Eye Study - NIES). No correlation between intensive sun exposure (resp. UV radiation) and a sharp increase in the dimensions of the UVAF zone is established, suggesting a chronic damage, in support of which is the demonstrative eye damage in people with high-risk occupations (associated with electric welding, lifeguards and other outdoor occupations). Insufficient sun protection habits and incompetence about the UV radiation are documented and analyzed with the questionnaire. 87% of the surveyed believe that there is a risk of UV damage only in the summer. A significant percentage (55%) do not pay attention to the special protective equipment such as umbrellas and caps Conclusions: The survey results are based on the thesis, that conjunctival UV autofluorescence is an objective marker of UV exposure. In 83 of the 123 subjects (67.48 %), there is evidence of conjunctival autofluorescence. As age increases, the area and the intensity of UVAF also increase, assuming that the area corresponds to a chronic damage. The degree of damage correlates to a large extent to the bad sun protection habits demonstrated in the questionnaire.

Quantification of sun-related changes in the eye in conjunctival ultraviolet autofluorescence images.

Quantification of sun-related changes in conjunctival ultraviolet autofluorescence (CUVAF) images is a subjective and tedious task, in which reproducibility of results is difficult. Thus, we have developed a semiautomatic method in MATLAB(®) to analyze CUVAF images retrospectively. The algorithm was validated on 200 images from 50 randomly selected participants from the Western Australian Pregnancy Cohort (Raine) study 20-year follow-up assessment, in which CUVAF area measurements were available from previous manual analysis. Algorithm performance was compared to manual measurements and yielded better than 95% correspondence in both intra- and interobserver agreement. Furthermore, the semiautomatic method significantly reduced analysis time by 50%.

The use of conjunctival ultraviolet autofluorescence (CUVAF) as a biomarker of time spent outdoors.

Conjunctival ultraviolet autofluorescence (CUVAF) has been used in previous Southern Hemisphere myopia research as a marker for time spent outdoors. The validity of CUVAF as an indicator of time spent outdoors is yet to be explored in the Northern Hemisphere. It is unclear if CUVAF represents damage attributed to UV exposure or dry eye. This cross-sectional study investigated the association between CUVAF measures, self-reported time spent outdoors and measures of dry eye. Participants were recruited from University staff and students (n=50, 19-64years; mean 41). None were using topical ocular medications (with the exception of dry eye treatments). Sun exposure and dry eye questionnaires (Ocular Surface Disease Index and McMonnies) were completed by the participant. Dryness was also assessed using slit lamp biomicroscopy and invasive tear break up time. Images of the temporal and nasal conjunctiva from the right and left eye were captured using a bespoke photography system. The total CUVAF area, average CUVAF pixel intensity per mm(2) and total CUVAF pixel intensity were analysed using MATLAB R2013a (The MathWorks Inc). Of the 50 participants, 42% were classified as having dry eye. Self-reported sunglasses use was negatively associated with all CUVAF measures (Kruskal Wallis total CUVAF area, p=0.04, ptrend =0.03, average CUVAF pixel intensity p=0.02, ptrend =0.02, total CUVAF pixel intensity: p=0.04, ptrend =0.02). Time spent outdoors was positively associated with all CUVAF measures (Spearman's correlation coefficients, total CUVAF area: r=0.37, p=0.01, average CUVAF pixel intensity: r=0.36, p=0.01, total CUVAF pixel intensity: r=0.37, p=0.01) and remained significant when sunglasses use was controlled for (partial correlation, total CUVAF area: r=0.32, p=0.03, average CUVAF pixel intensity: r=0.39, p=0.01, total CUVAF pixel intensity: r=0.39, p=0.03). Neither CUVAF area nor intensity measures were associated with any dry eye measure (Ocular Surface Disease Index: all p≥0.41, corneal staining: all p≥0.38, McMonnies: all r≤0.09 all p≥0.52, slit lamp biomicroscopy: all r≤0.20 all p≥0.17, invasive tear break up time: all r≤-0.07 all p≥0.31). CUVAF area and intensity were not associated with clinical measures of dry eye. Greater CUVAF area and intensity were associated with wearing sunglasses less frequently and spending more time outdoors. If sunglass wear is accounted for, CUVAF may be a useful biomarker of time spent outdoors in future myopia studies.

Sun protection habits and ocular UV damage of the Bulgarian population, first results using the method of conjunctival ultraviolet fluorescence

The purpose of this study is to present our first data and impressions of the sun protection habits and conjunctival ultraviolet autofluorescence (UVAF) of a randomly selected target group. Materials and Methods : A prospective, randomized study, including photographs of 123 subjects (246 eyes) and 200 questionnaires. Subsequently UV photography based on autofluorecence was used. For each eye three pictures were taken - eye in first position, temporal gaze (documenting nasal part of the limbus) and nasal gaze (documenting temporal part of the limbus). Results : Results are based on the study of 123 subjects (246 eyes). The participants in the study were aged between 5 and 88 years (average age=39). 87% of the surveyed believe that there is a risk of UV damage only in the summer. A significant percentage (55%) do not pay attention to the special protective equipment such as umbrellas and caps. Photography results were analyzed with specialized software and showed that 83 participants (67.48%) have conjunctival autofluorescence, as women prevail (women n=47 persons, men n=36 persons). The area of conjunctival UVAF tends to increase with age. No correlation between intensive sun exposure (resp. UV radiation) and a sharp increase in the dimensions of the UVAF zone is established, suggesting a chronic damage, in support of which is the demonstrative eye damage in people with high-risk occupations (associated with electric welding, lifeguards and other outdoor occupations). Conclusions : We suggested that the area and the intensity of UVAF increases with age, and probably corresponds only to a chronic damage. The degree of damage correlates to a large extent to the bad sun protection habits demonstrated in the questionnaire.

Pterygium and conjunctival ultraviolet autofluorescence in young Australian adults: the Raine study.

Sun exposure is associated with several ophthalmic diseases, including pterygium which may develop in adolescence. This study reports the prevalence of pterygium and its associations in a large cohort of young Australian adults. Conjunctival ultraviolet autofluorescence, a biomarker of ocular sun exposure, has recently been characterized in some Australian populations. Cross-sectional population-based study. One thousand three hundred forty-four subjects aged 18-22 years in the Western Australian Pregnancy Cohort (Raine) Study. Standardized colour and ultraviolet autofluorescence photographs of the nasal and temporal conjunctiva were taken, and assessed for presence of pterygium and area of autofluorescence. Sun exposure and protective factors were assessed by structured questionnaire. Area of conjunctival ultraviolet autofluorescence in square millimetre (mm(2)) and presence of pterygium. Median total conjunctival autofluorescence was 44.2 mm(2) (interquartile range 20.2-69.8 mm(2)). Median conjunctival autofluorescence was higher in nasal than in temporal quadrants (23.8 mm(2) vs. 18.9 mm(2), P < 0.001), but did not differ according to age or gender. Higher body mass index was associated with lower levels of autofluorescence. Total autofluorescence increased with increasing time spent outdoors. Prevalence of pterygium was 1.2% (95% confidence interval 0.6-1.8%), and was associated with male gender (odds ratio 6.71, P = 0.012). Participants with pterygium had significantly more conjunctival autofluorescence than those without (median 73.4 mm(2) vs. 44.0 mm(2), P = 0.001). Conjunctival ultraviolet autofluorescence is associated with increased time spent outdoors, and increased prevalence of pterygium. The association of this biomarker with other ophthalmohelioses, including cataract, ocular surface squamous neoplasia and eyelid malignancy, has yet to be determined.

Myopia in Young Adults Is Inversely Related to an Objective Marker of Ocular Sun Exposure: The Western Australian Raine Cohort Study

To determine the association between ocular sun exposure measured by conjunctival ultraviolet (UV) autofluorescence and myopic refractive error in young adults. Cross-sectional study. setting: Population-based cohort in Western Australia. study population: Total of 1344 mostly white subjects aged 19-22 years in the Western Australian Pregnancy Cohort (Raine) Eye Health Study. observation procedures: Cycloplegic autorefraction, conjunctival ultraviolet autofluorescence photography, participant questionnaire. main outcome measures: Prevalence of myopic refractive error (spherical equivalent less than -0.50 diopters) and area of conjunctival ultraviolet autofluorescence in mm(2). There was an inverse relationship between myopic refractive error and ocular sun exposure, with more than double the prevalence of myopia in the lowest quartile of conjunctival autofluorescence than the highest quartile (33.0% vs 15.6%). Median area of autofluorescence was significantly lower in myopic than in nonmyopic subjects (31.9 mm(2) vs 47.9 mm(2), P < .001). These differences remained significant after adjustment for age, sex, parental history of myopia, and subject level of education. The use of corrective lenses did not explain the lower conjunctival autofluorescence observed in myopic subjects. In this young adult population, myopic refractive error was inversely associated with objectively measured ocular sun exposure, even after adjustment for potential confounders. This further supports the inverse association between outdoor activity and myopia.

The association between pterygium and conjunctival ultraviolet autofluorescence: The Norfolk Island Eye Study

To investigate the association between conjunctival ultraviolet autofluorescence (UVAF), a biomarker of ocular ultraviolet radiation (UVR) exposure, and prevalent pterygium. We conducted a cross-sectional study on Norfolk Island, South Pacific. All permanent residents aged ≥15 were invited to participate. Participants completed a sun exposure questionnaire and underwent autorefraction and slit lamp biomicroscope examination. Area of conjunctival UVAF (sum of temporal/nasal area in right and left eyes) was determined using computerized methods. Multivariate logistic and linear regression models were used to estimate the associations with pterygia and UVAF, respectively. Of 641 participants, 70 people (10.9%) had pterygium in one or both eyes, and prevalence was higher in males (15.0% versus 7.7%, p = 0.003). Significant independent associations with pterygium in any eye were UVAF (per 10 mm(2)) [odds ratio (OR) 1.16, 95% confidence interval (CI) 1.16-1.28, p = 0.002], tanning skin phenotype (OR 2.17, 1.20-3.92, p = 0.010) and spending more than three-quarters of the day outside (OR 2.22, 1.20-4.09, p = 0.011). Increasing quartile of UVAF was associated with increased risk of pterygium following adjustment of age, sex and time outdoors (p(Trend) = 0.002). Independent associations with increasing UVAF (per 10 mm(2)) were decreasing age, time outdoors, skin type and male gender (all p < 0.001). UVAF area correlated well with the duration of outdoor activity (p(Trend) < 0.001). Pterygium occurs in approximately one-tenth of Norfolk Islanders. Increasing conjunctival UVAF is associated with prevalent pterygia, confirming earlier epidemiological, laboratory and ray-tracing studies that pterygia are associated with UVR. Protection from the sun should be encouraged to reduce the prevalence of pterygium in the community.