Chinese University endorses use of a safe pen-like tester to detect the disease Eye specialists have recommended that people at risk of glaucoma, the leading cause of blindness in Hong Kong, be given a self-testing device to detect the onset of the condition. The pen-like object, which measures pressure levels in the eyeball, was proclaimed accurate, safe and generally acceptable to patients after tests by Chinese University's department of ophthalmology and visual sciences. Glaucoma is a disease where the optic nerve at the back of the eye is slowly destroyed. It is one of the leading causes of blindness and vision loss, affecting up to 90 million people worldwide. People aged over 40 with a family history of glaucoma or suffering from diabetes are considered to be at high risk of the disease, which afflicts an estimated 100,000 people, or 3 per cent of the over-40s. Chinese people are more likely to suffer from an acute form of glaucoma and turn blind than any other race. Other than early detection and treatment there are no known preventive measures for the condition, which is caused by high pressure of liquid in the eyeball. The visual science department endorsed the use of the self-testing device, the Pressure Phosphene Tonometer (PPT), after a clinical study involving 102 glaucoma patients. The department's chairman, Dennis Lam Shun-chiu, said it was inexpensive and portable, making it a good candidate for home monitoring of eye pressure levels. He said its major advantage over other devices was that it could be applied by the individual and did not require direct contact with the cornea. Applied to the upper eyelid, the device shows the pressure reading on a scale. A reading of 6 to 21 mm of mercury (mmHg) - a standard measurement - is considered normal, but the pressure can mount to 60 or 70 in glaucoma patients. Dexter Leung Yu-lung, the university's honorary clinical assistant professor, said home monitoring was useful because pressure levels fluctuated at different times of the day. The device was first used in the United States and became available in Hong Kong in 2002. It can be bought from ophthalmologist clinics for about $600 but training is needed to ensure measurements are taken accurately. 'Our suggestion is that patients consult with their doctor to learn how to use the device and to verify the results,' said Professor Lam. A glaucoma patient for 10 years, who gave his name only as Mr Lam, said the device was very easy to learn how to use, and 'now I carry it around with me all the time'. Mr Lam, 44, said the pressure in his eyes fluctuated wildly and caused blurred vision and discomfort. 'Before I used PPT, sometimes when I saw the doctor the pressure was already very high and I had to take medications and have injections,' he said. 'In the two years since I have used PPT I have only required heavy treatment once.'