76% Hong Kong contact lenses users have Corneal Oxygen Deficiency (COD) symptoms due to long-hour work. Survey says.<br>New generation high permeable lenses answer calls for work efficiency and COD risk reductionBack

Date of Release: July 12, 2004

With long working hours in Hong Kong, wearing contact lenses has become part of the work life of many white collar workers. How to maintain high comfort level with lenses in eyes has become a special topic of interests. A recent survey tells how work-savvy workers attempt to maintain in good shape but have poor understanding of the root cause of discomfort - Corneal Oxygen Deficiency (COD). Eye expert warns that extended lens wear with low permeable lenses will lead to corneal oxygen deficiency, a condition that will jeopardize ocular health if unattended.

The survey, titled "Hong Kong Workers' Long-hour of Contact Lenses In Relations to Corneal Oxygen Deficiency Survey", was commissioned by Ciba Vision and conducted by the Public Opinion Programme of the University of Hong Kong, through telephone interviews from June 10 to June 15. A total of 509 samples of full time workers aged 25-44 years old who had worn contact lens in the past twelve months were collected. The results are announced today in a press conference by Dr. Robert Chung, Director of Public Opinion Programme, the University of Hong Kong.

76% experienced COD symptoms
In the survey, as many as 76% experience COD symptoms, such as dried eyes (76%), weary eyes (75%), and blood shot eyes (61%). 45% respondents experience blurred vision, 36% experience itchy eyes, 28% and 27% report eyes with pain and tears respectively.

High COD risks resulting from long-hour wear and napping with lenses on
Extended wear of contact lenses with low permeable lenses and napping with lenses on are the two key risk factors leading to COD. According to the respondents, 29% interviewees have to wear contact lenses for work for at least ten hours a day, 7% need to wear contact lenses for at least 12 hours a day. 84% eye-weary workers have napped with their contact lenses on.

COD sufferers only use symptom-relieving measures, never deal with the root cause
With long hours wearing contact lenses at work, many find different ways to keep themselves comfortable and maintain efficiency, such as: Take eye-drop (47%); Take off the lenses and change to ordinary glasses (22%); Take off the lenses and rest for a while (20%); Simply close the eyes and rest (10%); Take off the lenses and cleanse and put them on again (5%).

According to Dr. Robert Chung, the findings of the survey is a manifestation of how most Hong Kong full time workers seek to remain comfortable in order to maintain efficiency. "In this highly competitive environment, many workers work extensive hours while wearing contact lens, so they should care more about COD, as many of them might be experiencing COD symptoms without being fully aware of it. However, they lack the knowledge of the root cause of their eye problems and are obviously using the wrong methods to rectify. Ideally, they should try to consult their ophthalmologist or optometrists for professional advice." Dr. Chung said.

Wearing conventional low permeable contact lenses will cause COD
According to Mr. John Wong, Registered Optometrist, a 10% decrease in oxygen to the cornea will cause hypoxic changes in as little as 5 minutes, and the effects of COD can be cumulative. COD signs are alarming, which include bloodshot, damages in corneal endothelium (polymegathism), myopic shift, corneal edema, and blood vessels growing into the cornea (neovascularisation). It will increase bacterial binding, making the eyes more vulnerable to infection (cornea inflammation). Among different signs, polymegathism and neovascularisation are irreversible and there is no medication available for treatment.

Body cells need oxygen to maintain its metabolism. For most body organs, oxygen is supplied by blood vessels. But for eye tissues, the corneal does not contain blood vessels and thus eye cells must rely on atmospheric environment for oxygen supply. Corneal oxygen deficiency is normally a result of wearing low permeable contact lens for long hours, which blocks sufficient oxygen from entering into the eyes. As a matter of fact, early COD symptoms are difficult to detect. Also, COD symptoms carry many similar symptoms of dry eyes, prompting many red-eyed workers to take eye drops for relief, which according to optometrist can only provide temporary solution for the wrong cause. "People suffering from polymegathism and neovascularisation may not be able to wear contact lenses thereafter. Thus, it is important that all contact lens wearers should visit their optometrists on a regular basis for their eye check. " Mr. Wong noted.

New generation high permeable lens will become new standard for comfort and efficiency
Technological breakthrough has made possible a new material, silicone hydrogel, for the production of high permeable contact lenses. The result is the availability of a super high oxygen permeable contact lenses at Dk/t 175, compared to the existing daily wear contact lenses at Dk/t 25. This new generation high permeable contact lenses can allow 5 times more oxygen to penetrate through the lenses, promising healthy and comfortable lens wear for long hours.

According to the survey, when respondents were informed of the risk of COD, 86% will choose lenses with high oxygen permeability, while 71% believe lenses of high permeability will minimize the risk of lack of oxygen and increase work efficiency. "It is difficult to tell how much oxygen is enough, as needs for oxygen will vary according to individual's metabolic rate and environmental factors such as height and weather. However, in today's hectic world where people have to wear lenses for long hours or will nap easily, consumers should take into consideration oxygen permeability when choosing contact lenses." Mr. Wong commented.

This press release serves only as public education materials on COD and eye care. The information in this press release shall not replace the professional advice from optometrists. Members from the public (especially those with corneal problems) should first consult their optometrists for professional advice before replacing contact lenses.

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