Factors causing eye dryness in contact lens wearers

Cristina G. Pedraz/ DICYT According to estimates, half of the people giving up contact lenses are motivated by discomfort linked to eye dryness. The optical industry has been working to solve this problem and to reduce these high percentages, to do so, it is necessary to delve into all factors associated with eye dryness and its effects on contact lenses. Researchers from the GSO (Eye Surface Team) at the IOBA (an institute of applied ophthalmology) in Valladolid (Spain) are working on this area and are currently developing a study with 60 patients.

According to IOBA researcher María Jesús González, the study is part of the doctoral thesis by Vincente Martín and is being conducted with the Universidade do Minho (Braga, Portugal). Its major objective is to identify the differences between contact lens wearers with clinical signs (red eyes, tearing, etc.) and wearers without signs. Although this is just the first step, understanding differences “will enable us to detect patients with potential problems that are to give up contact lenses”.

Environmental factors are to be taken into account for the study. “There is a difference between being in Valladolid, with a relative humidity of around 40-45% and being in a coastal zone with an humidity of 80%. Contact lens wearers are more comfortable in a humid environment,” the expert states. Likewise, other environmental factors such as air flow, temperature and atmospheric pressure also affect wearers. In order to study these factors, volunteers are to undergo different environmental conditions in a controlled environment chamber that the IOBA has built in the center.

Moreover, molecular markers are to be analyzed: “proteins or tears secreted by the eye surface that somehow are able to show us what is happening at the molecular level in these patients,” González states. Finally, they are studying the sensitivity of the cornea in order to “find out if it is related to the fact that the patient has more or less dryness symptoms”.

Nearsighted Volunteers

The GSO has been planning this project for about two years, and has already examined 45 individuals. In order to finish the study, they need more volunteers: women and men between 18 and 45 years old with up to 5.00 diopters, wearing contact lenses or not.

Contact lens wearers must attend five times: the first one to perform tests to know whether they meet the criteria for the study; the others, to undergo various controlled environmental conditions for a given time, wearing two types of lenses, watching TV or using the computer. For those not wearing lenses, a single visit is enough to carry out all tests.

A Unique Facility

The controlled environment chamber at IOBA contains 38,000 pounds of steel and is able to recreate extreme environmental conditions affecting the human eye in certain situations, such as transoceanic flights. This chamber enables them to calibrate environmental features such as humidity, pressure or temperature, allowing all kinds of trials for new drugs and ophthalmic solutions. Accordingly, the chamber may help to solve the dry eye syndrome (the reduction of the amount of tears produced), increasingly affecting a larger number of people. To date, clinical studies developed to mitigate its effects have not taken into account standardized conditions or systems efficiently reproducing the extreme conditions human beings undergo, such as flights, working environments with air conditioning or heating system without a proper air exchange or certain positions in the industry.   Furthermore, the facilities will be used to find out, with scientific basis, the behavior or certain drugs, tolerance to new contact lenses and cleaning and maintenance solutions and new diagnostic technique for eye surface conditions, such as allergy. Finally, it will help scientists to assess the effects of chronic use of drugs or refractive eye surgery.