Carboxymethyl Cellulose versus Hydroxypropyl Methylcellulose Tear Substitutes for Dry Eye Due to Computer Vision Syndrome: Comparison of Efficacy and Safety

As per the DEWS II global dry eye definition, “Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film and accompanied by ocular symptoms, in which tear film instability, hyperosmolarity, ocular surface inflammation, and damage along with neurosensory abnormalities play etiological roles.” The prevalence of dry eye syndrome increases with age and ranges from 5.5% to 37.7%. In the Indian population, hospital-based prevalence of dry eye has been reported to vary from 18% to 27%.

The etiology of dry eye still remains unclear though some known risk factors are older age, female gender, arthritis, smoking, hormone-replacement therapy, and environmental factors such as low relative humidity.Prolonged exposure to visual display terminals images on electronic devices such as computers and video games leads to reduced blink rate, which generate ocular discomfort and subsequently dry eye.

The Occupational Safety and Health Administration department of US Government has defined computer vision syndrome (CVS) as a “complex of eye and vision problems that are experienced during and related to computer use; it is a repetitive strain disorder that appears to be growing rapidly in workers using computers for more than 3 h/day.”

A key principle for the management of dry eye disease is an augmentation of tear film through the topical administration of artificial tear substitutes. These tear substitutes are the mainstay of treatment for mild-moderate dry eye symptoms. These products enhance tear stability and help to retain moisture in eye, thus relieving the symptoms of CVS.

Carboxymethyl cellulose (CMC) is a cellulose polymer with a carboxylic group and has a high viscosity. It has bioadhesive properties, and its anionic nature may be the reason for high retention time on the cornea. Hydroxypropyl methylcellulose (HPMC), also known as hypromellose, is a semisynthetic polymer. It is less viscous than CMC due to its molecular size but is known to have emollient properties.

In this study, we compared the efficacy and safety of two commonly used tear substitutes containing CMC 0.5% and HPMC 0.3% in participants diagnosed with dry eye due to CVS. This was the first time two commonly used tear substitutes were compared in CVS using both qualitative and quantitative tests of dry eye disease.