Assessment of Ocular Tear Film Stability in Subjects with High Total Cholesterol Levels

Abstract
Background: High cholesterol levels are known to cause multiple complications and the correlations between dry eye disease and high cholesterol levels can be used as an indicator of the need for urgent treatment to prevent severe ocular complications.
Aim of Study: This study aimed to assess ocular tear film stability in subjects with high total cholesterol levels by using various dry eye diagnostic tests.
Subjects and Methods: Twenty male subjects aged 19-43 years (32.5±7.3 years) with a high total cholesterol level (6.2±0.7mmol/L) and an age-matched control group of twenty male subjects (19-40 years; 31.1±4.6 years) with normal total cholesterol levels (3.9±0.6mmol/L) participated in the study. All subjects completed the ocular surface disease index assessment first, followed by the non-invasive tear break-up time (NITBUT) test. After 10 minutes, the tear meniscus time (TMH) test was performed followed by phenol red thread (PRT) and tear ferning (TF) tests, with a 10-minute gap between the tests.
Results: The mean scores (p<0.05) in the NITBUT and TMH tests indicated a dry eye condition in the study group [7.5 (3.3) s and 0.15 (0.12) mm, respectively] and a normal eye condition in the control group [15.3 (4.1) s and 0.27 (0.06) mm, respectively]. The average score for the TF grade (p<0.05) showed eye dryness [2.2 (1.8)] in the study group and a normal eye condition in the control group [0.5 (1.5)]. The cholesterol level showed a medium correlation with age (r=0.473; p=0.035), a strong negative correlation with the PRT score (r=-0.524; p=0.018), and a strong correlation with the TF grade (r=0.530; p=0.016).
Conclusion: The total cholesterol level significantly influences ocular tear film stability. Both tear quantity and quality decreased in subjects with high total cholesterol levels, which led to meibomian gland dysfunction and disturbances in lipid production and blood and oxygen supply to eye tissues, thereby causing dry eye symptoms.