More than half a million Hongkongers suffer from dry-eye syndrome, yet there is a lack of awareness and knowledge of treatment options, an expert from the University of Hong Kong says. The disease occurs when there is insufficient moisture on the eye surface. Symptoms include blurred vision, burning, itchiness and inflammation. Sufferers can also find it difficult to perform activities such as using a computer and reading for a prolonged time and, if untreated, the disease can lead to pain, scars on the cornea and some loss of vision. Many of those affected regularly use eye drops and gel. Dr Marcus Marcet from the university's department of opthalmology attributed the large number of sufferers to an ageing population, pollution and the increased use of computers in offices. Dry-eye syndrome is also a common temporary aftermath of laser eye surgery to treat short-sightedness as the treatment cuts across nerves in the eyes, making them unable to detect dryness. Marcet said many Hongkongers were unaware that they could receive insertions to plug the tear duct to prevent tears being drained. The insertions consist of dissolvable collagen plugs, removable silicone, acrylic plugs (punctal plugs) or "permanent" inserts (intracanalicular plugs) which are inserted deeper into the tear duct. Patients can also choose to surgically close their tear duct. A study at the American Academy of Ophthalmology - for which Marcet was a contributing researcher - looked at the safety and effectiveness of tear duct plug insertions. The study was conducted to "bring some clarity to a product that we didn't know enough about … We can really give the patient more data and information," Marcet said. It found that 50 per cent of plug users showed improvement in their symptoms, while 9 per cent experienced tearing and 10 per cent suffered irritation. For punctal plugs, 40 per cent of patients reported that the devices fell out. In spite of this, Marcet said "non-permanent" plug insertions were preferred as there was a risk of inflammation and infection with permanent ones. Before considering plug insertions, Marcet suggested that dry-eye sufferers should receive more treatment with eye drops and be aware of dry, air-conditioned environments.