Prevalence of Dry Eye Disease among Elderly Korean Population Sang Beom Han, MD, 1 Joon Young Hyon, MD, 1 Won Ryang Wee, MD, 2,3 Jin Hak Lee, MD, 1, 3 Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital 1, Seongnam, Korea Department of Ophthalmology, Seoul National University College of Medicine 2, Seoul, Korea Seoul Artificial Eye Center, Seoul National University Hospital Clinical Research Institute 3, Seoul, Korea Financial Disclosure: None

Background  Prevalence of Dry Eye Several population-based studies have reported prevalence of dry eye from 4.3% to 52.1%. Large disparity in reported prevalence of dry eye Lack of standardized diagnostic definition Difference in the study population.  Risk Factors of Dry Eye A few risk factors including old age, female gender, and hazardous environment have been assumed to be associated with dry eye. Ethnic difference in the prevalence of dry eye between Caucasian and Asian population has been suggested. Schein et al. Am J Ophthalmol 1997;124: Shimmura et al. Cornea 1999;18:

Purpose  To assess the population-based prevalence of dry eye in elderly Korean population.  To investigate the associated risk factors and affected quality of life.  Conducted from May 2008 to February 2009 in Yongin city, Korea.  Why Yongin? Yongin was considered to be an ideal community for a population- based study in Korea since it is one of the largest cities with rural/urban mixture in Korea.

4 Sample Towns within Yongin were randomly selected to cover about 10,000 residents aged 65 years old or above. 10% of them were randomly drawn, and finally 1,060 elderly subjects were sampled. 657 agreed to participate in this study and completed a symptom questionnaire.

Two-Stage Design  Phase I population survey Dry Eye Questionnaire (DEQ) Schirmer test  DEQ During recent 2 weeks 1.Do your eyes feel dry? 2.Do you feel gritty or sandy sensation in your eyes? 3.Do your eyes ever have a burning sensation? 4.Do your eyes ever feel sticky? 5.Do your eyes ever feel watery or tearing? 6.Are your eyes ever red?  Allowed responses to the questions were ‘none”, ‘rarely’, ‘sometimes’, and ‘often or all the time’.  Dry eye was defined as having one or more symptoms often or all the time.

Phase II evaluation  Tear film breakup time (BUT) test  Fluorescein stain  Examination of meibomian gland dysfunction  Positive signs were defined as Tear film BUT ≤10 seconds Schirmer test score ≤ 5 mm Fluorescein score ≥ 1 or the presence of meibomian gland disease

Statistical Analysis  In each subject, the worse eye was used for analyses.  Standardized prevalence rates were also estimated using the direct standardization method. The prevalence rates were adjusted by age, gender, and urbanicity to the total Korean population, as given in the 2005 national census.  Association between demographic variables (age, sex, and area) and dry eye symptoms or signs was evaluated using Pearson Chi-square tests.

Results  Total 657 subjects Mean age was 72.0 ± 5.9 years (mean ± SD, range 65-95) M : F ratio was 48.2%: 51.8% (317 : 340) Schirmer test was completed in 648 subjects  139 subjects completed this Phase II evaluation.  Prevalence of Dry eye The crude prevalence rate, define as presence of one or more of the six dry eye symptoms, was 30.3%. Sex, age, and area adjusted prevalence based on the Korea 2005 census population was 33.2% (95% CI ).

Prevalence rates According to the potential predictors Variables Positive dry eye symptoms No Crude rate % Adjusted rate % (95% CI) P value Odds Ratio (95% CI) Total rate199 / ( ) Age groups ≥85 84 / / / / / ( ) 33.3 ( ) 35.1 ( ) 31.1 ( ) 35.7 ( ) Sex Male Female 81/ / ( ) 37.7 ( ) ( ) Area Urban Rural 125 / / ( ) 23.7 ( ) (1.29 – 2.55)

Dry Eye Signs  Frequency of positive dry eye tests according to the presence or absence of dry eye symptoms. Variables No (%) P value Odds Ratio (95% CI) Positive dry eye symptoms Negative dry eye symptoms Schirmer I test ≤ 5 mm63 / 192 (32.9%)113 / 456 (24.8%)0.042*1.48 (1.03 – 2.14) BUT ≤10 seconds63 / 74 (85.1%)56 / 65 (86.1%) (0.36 – 2.38) Fluorescein score ≥ 129 / 74 (39.1%)21 / 65 (32.3%) ( ) Presence of meibomian gland disease 40 / 74 (54.1%)32 / 65 (49.2%) (0.62 – 2.37) *Only Schirmer test score was shown to have significant association with positive dry eye symptoms, although the test also showed high false-positive rate

Risk factors  Ethnicity High prevalence of 33.2% in this study is similar to those among Asians, but much higher than those among Caucasians.  Gender Sex hormones may influence ocular surface condition through their effects on lacrimal gland, meibomian glands, conjunctival goblet cell density, and ocular surface sensitivity.  Area The exact cause is yet to be elucidated, although air pollution in the urban region may, at least in part, contribute to the difference.

Conclusion  Dry eye is very common condition with an estimated national prevalence of 33.2% among elderly Koreans population.  Women and urban dwellers are more likely to suffer from dry eye symptoms.