Prevalence and risk factors of keratoconus (including oxidative stress biomarkers) in a cohort study of Shiraz university of medical science employees in Iran

Abstract

Background To determine the prevalence of keratoconus in Shiraz University of Medical Sciences Employees and the related risk factors including oxidative stress biomarkers. Methods 2546 subjects’ mean age ± SD, 40.35 ± 6.70 (46% male) were recruited. All participants underwent objective refraction using auto-refractometer and retinoscopy, followed by subjective refraction, and bio-microscopy. Pentacam imaging was performed for the detected keratoconus patients. The prevalence of keratoconus and frequency of the visual impairment among keratoconus cases were evaluated. Potential risk factors of sex, age, family history of keratoconus, body mass index ≥ 30 kg/m2, serum levels of glucose ≥ 100 mg/d, low-density-lipoprotein-cholesterol (LDL) ≥ 110 mg/dL, high-density-lipoprotein-cholesterol ≤ 40 mg/d, and triglycerides ≥ 150 mg/dL in the blood were evaluated. Results The prevalence of keratoconus at least in one eye was 0.98% (95% CI: 0.6- 1.4%). The best corrected visual acuity in the keratoconus group was 0.06 ± 0.1 and the rest of the population was 0.01 ± 0.07 logMAR (p < 0.001). The frequency of visual impairment in the keratoconus group was zero. Odds ratios of the family history of keratoconus (21.00, 95% CI: 9.00–48.00, p < 0.001) and LDL ≥ 110 mg/dL (3.00, 95% CI: 1.20–6.40, p = 0.01) were significant. Conclusions Keratoconus is rare and is not considered a risk factor for visual impairment. A family history of keratoconus and elevated serum LDL levels are contributing risk factors, suggesting an inflammatory background for the disease. Serum levels of LDL ≥ 110 mg/dL in the blood increased the risk of keratoconus three folds.

A high body mass index strengthens the association between the time of eye rubbing and keratoconus in a Chinese population: a case control study

“…A case‒controlled multicenter study in a Turkish population found that the mean BMI values in both the KC and control groups were within normal ranges [ 15 ]. No significant difference was found between KC and non-KC subjects in an Iran study [ 17 ]. Slater JA et al [ 23 ] reported a ratio of 5% KC in 60 obese patients awaiting bariatric surgery, with a 100-fold increased prevalence compared with the overall population (0.05%), although the difference was not statistically significant due to the small sample size.…”

“…Until now, several limited studies have been conducted to explore the relationship between BMI and KC. Although several studies have failed to confirm that BMI is a risk factor for KC [ 15 , 17 ], a nationwide study suggested an strong independent association between BMI and KC [ 9 ]. Furthermore, there is still a lack of evidence on the interactive effect of eye rubbing and BMI on KC, which are all closely related to the expression of inflammatory mediators.…”

Exploring the causal relationship between body mass index and keratoconus: a Mendelian randomization study

“…To date, the impact of high BMI on keratoconus remains unclear. Past reports have indicated that in Australian patients ( 11 ), a higher BMI was not associated with an increased risk of keratoconus; a recent study in Iran ( 12 ) found no significant difference in BMI between keratoconus patients and control subjects. However, recent findings suggest that a high BMI may be a risk factor for keratoconus.…”