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Pollution, Skin damage, and Dry eye

June 2017

Dry eye

A randomized controlled trial of omega-3 fatty acids in dry eye syndrome.

AIM: To evaluate the role of dietary supplementation of omega-3 fatty acids in dry eye syndrome. METHODS: A prospective, interventional, placebo controlled, double blind randomized trial was done at two referral eye centers. Two hundred and sixty-four eyes of patients with dry eye were randomized to receive one capsule (500mg) two times a day containing 325mg EPA and 175mg DHA for 3 months (omega-3 group). The omega-3 group was compared to a group of patients (n=254) who received a placebo (placebo group). There were 4 patient visits (at baseline, 1 month, 2 months and 3 months). On each visit, recording of corrected distance visual acuity (CDVA), slit lamp examination and questionnaire based symptom evaluation and scoring was done. A symptomatic score of 0-6 was mild, 6.1-12 moderate and 12.1-18 severe dry eye. Response to intervention was monitored by routine tear function tests like Schirmer I test, tear film break-up time (TBUT), Rose Bengal staining and most notably, conjunctival impression cytology. RESULTS: Sixty-five percent of patients in the omega-3 group and 33% of patients in placebo group had significant improvement in symptoms at 3 months (P=0.005). There was a significant change in both Schirmer's test value and TBUT values in the omega-3 group (P<0.001), both comparisons. However, there was a larger drift in TBUT values in omega-3 than the placebo group, in comparison to Schirmer's test values. The mean TBUT score was 2.54±2.34 in the omega-3 group and 0.13±0.16 in placebo group, respectively. The mean reduction in symptom score in omega-3 group was 2.02±0.96 as compared to 0.48±0.22 in placebo group (P<0.001). Despite a slight increase mean score, the Schirmer scores did not correlate well with symptomatic improvement. CONCLUSION: Omega-3 fatty acids have a definite role for dry eye syndrome. The benefit seems to be more marked in conditions such as blepharitis and meibomian gland disease. The role of omega fatty acids in tear production and secretion needs further evaluation.

Int J Ophthalmol. 2013 Dec 18;6(6):811-6

Are higher blood mercury levels associated with dry eye symptoms in adult Koreans? A population-based cross-sectional study.

OBJECTIVES: The purpose of this study was to investigate whether blood mercury concentrations associated with the presence of dry eye symptoms in a nationally representative Korean population. METHODS: Population-based prospective cross-sectional study using the heavy metal data set of the 2010-2012 Korean National Health and Nutrition Examination Survey (KNHANES). A total of 4,761 adult Koreans were the eligible population in this study. Of the 7,162 survey participants, 2,401 were excluded because they were <19 years of age, there were missing data in the heavy metal data set, or they had diabetes, rheumatoid arthritis, thyroid disease, asthma, depression and/or under-the-eye surgery. Blood mercury levels were measured on the day the participants completed a questionnaire regarding the presence of dry eye symptoms (persistent dryness or eye irritation). The population was divided into low and high groups by median level (4.26 and 2.89 µg/L for males and females, respectively). RESULTS: Self-reported dry eye symptoms were present in 13.0% of the cohort. Participants with dry eye symptoms were significantly more likely to have blood mercury levels exceeding the median than those without dry eye symptoms (45.7% vs 51.7%, p=0.021). Logistic regression analysis showed that, after adjusting for age, gender, education, total household income, smoking status, heavy alcohol use, sleep time, perceived stress status, total cholesterol levels and atopy history, dry eye symptoms were significantly associated with blood mercury levels that exceeded the median (reference: lower mercury group; OR, 1.324; 95% CI 1.059 to 1.655; p<0.05). CONCLUSIONS: High blood mercury levels were associated with dry eye symptoms in a nationally representative Korean population.

BMJ Open. 2016 Apr 27;6(4):e010985

Pharmacological management of dry eye in the elderly patient.

Dry eye disease is a common and increasingly prevalent condition particularly associated with advancing age and postmenopausal women. Epidemiological studies identify prevalence rates ranging from 7% in the US to 33% in the Asian population. Research increasingly identifies risk factors of increasing age, female sex, smoking, use of video display terminals and use of certain medications as well as environmental stresses as aggravating factors for the disease. Basic and clinical investigations provide cumulative evidence of hyperosmolarity of the tear film and ocular surface/lacrimal gland inflammation as pathogenic features of dry eye disease. A decline in systemic and local levels of sex hormones is associated with advancing age and advancing disease. Pharmacological therapeutic interventions include enhanced lubricants and anti-inflammatory drugs such as topical corticosteroids and ciclosporin (cyclosporine A). Secretagogues and hormonal supplementation are potential future therapies. The increased understanding of the contributing and pathogenetic factors responsible for dry eye provides a rationale for multiple therapeutic options for this multi-factorial disease. In the elderly patient it is important to recognize the physical and cognitive limitations that will influence the selection of appropriate topical medication.

Drugs Aging. 2008;25(2):105-18

The role and treatment of inflammation in dry eye disease.

Dry eye syndrome is a common ocular surface problem, affects 10-30 % of the population, especially in those who are older than 40 years. As a consequence of the demographic pressure created by the aging population, its prevalence is expected to increase as well as its burden on ophthalmologic practices. Thus, understanding the complex underlying mechanisms and development of thoughtful, effective strategies that involve these mechanisms are critical. Many factors causing ocular surface damage and inflammation have been shown to contribute to the etiopathogenesis. Increased osmolarity induces ocular surface inflammation leading to disruption of both the quality and quantity of tears. Pathologic tear function and the ocular surface inflammation affects the neural arcade and increases apoptosis in the ocular surface cells thus creating a viscous cycle for dry eye by causing unstable and hyperosmolar tears. Thus, the treatment objective is to prevent severe dry eye complications via preventing inflammation and apoptosis of the ocular surface cells. The ultimate target is a normalized ocular surface, increased tear stability, and decreased osmolarity of the tear film. In the light of current literature, this review aims to elucidate the role of inflammation as the main etiological factor in dry eye disease and discuss current therapeutic approaches to overcome it.

Int Ophthalmol. 2014 Dec;34(6):1291-301

Impact of evaporation on aqueous tear loss.

PURPOSE: To determine the impact of evaporation on preocular aqueous tear (AT) loss in normal subjects (controls) and patients with keratoconjunctivitis sicca (KCS). METHODS: Eighteen patients (32 eyes) with KCS with or without associated meibomian gland dysfunction (MGD) and 11 sex-matched controls had AT evaporation determined between relative humidity (RH) of 20% and 45% using an evaporometer. AT volume, flow, and turnover were determined with a fluorophotometer. RESULTS: Evaporative rates increased significantly when the RH was changed from 40%-45% to 20%-25% (P < .001). This change was similar in all groups and on average accounted for a 99.43% increase. There were no statistically significant differences in evaporative rate between controls, the KCS alone group, and the KCS/MGD group. Dry eye patients exhibited a decreased tear turnover when compared to controls. Evaporative contribution to tear loss at 40%-45% RH was 23.47% for controls, 30.99% for "classic" KCS patients, and 25.44% for KCS/MGD patients. At 20%-25% RH, the evaporative contribution was 41.66% for controls, 57.67% for classic KCS patients, and 50.28% for KCS/MGD patients. CONCLUSIONS: RH significantly impacts evaporation regardless of the presence of dry eye disease and probably accounts for the increased dry eye symptoms in people (controls and dry eye patients) in conditions of low RH (eg, deserts, airplane cabins, cold dry seasons). Contribution of evaporation to tear loss tends to be higher than previously described. The percent contribution is dependent on environmental conditions such as RH. There was a trend toward increased contribution to AT loss in dry eye patients vs controls, but statistical significance was not reached.

Trans Am Ophthalmol Soc. 2006;104:121-8

Etiology, prevalence, and treatment of dry eye disease.

PURPOSE: This review article examines the prevalence, etiology, and current therapies of dry eye disease, with special focus on postmenopausal women. METHOD: A systematic literature search utilizing MEDLINE was conducted to identify peer-reviewed articles related to dry eye published prior to September 2008. The terms "dry eye" and "women" were searched in combination with one or more of the following words or phrases: prevalence, postmenopausal, etiology, risk factors, therapy, medications, surgery, tear film, and quality of life. Articles were selected based on their direct applicability to the subject matter. A manual search was also conducted based on citations in the published literature. RESULTS: Epidemiologic studies identified prevalence rates ranging from 7% in the United States to 33% in Taiwan and Japan. Risk factors include advanced age, female sex, smoking, extreme heat or cold weather conditions, low relative humidity, use of video display terminals, refractive surgery, contact lens wear, and certain medications. CONCLUSION: The last decade has brought about a better understanding of the etiology of dry eye disease. New therapies that can alleviate the signs and symptoms of dry eye disease and, consequently, improve the quality of life of dry eye patients are available in the market.

Clin Ophthalmol. 2009;3:405-12

The impact of artificial tears containing hydroxypropyl guar on mucous layer.

PURPOSE: The aim of this study was to investigate the effect of lubricant eyedrops containing propylene glycol 400 (PEG) and polyethylene glycol (PG) with hydroxypropyl guar (HP-guar) as a gelling agent on the precorneal mucous layer in vivo. METHODS: Sixteen New Zealand white rabbits were randomly assigned to 1 of 4 groups. All rabbits received PEG/PG/HP-guar tear products in the right eye. PEG/PG/HP-guar with Polyquad, 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline was placed in the left eyes of animals in each group. All eyedrops were used 4 times a day for 7 days. An additional 8 rabbits were randomly assigned to 1 of 2 groups. One group received PEG/PG/HP-guar products 4 times a day for 7 days (long-term exposure group), and the other group received PEG/PG/HP-guar products 3 times at 5-minute intervals (short-term exposure group). Fifteen minutes after the last drop was administered, each cornea was immediately excised and mucous layer thickness measured by transmission electron microscopy. RESULTS: Mucous layer thickness was significantly greater in eyes treated with PEG/PG/HP-guar products compared with those treated with 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline (all P values < 0.001). There were no significant differences in mucous layer thickness between PEG/PG/HP-guar products and PEG/PG/HP-guar with Polyquad or in the long- and short-term exposure animals. CONCLUSIONS: This study demonstrates that even a short exposure to PEG/PG/HP-guar tear product increased precorneal mucous layer thickness.

Cornea. 2010 Dec;29(12):1430-5