2 April 2010
By Sahana Charan
Now, a new type of lens worn overnight gifts you near–perfect through your working day. But doctors warn that long–term use could lead to infection and worsen vision
The lens, also known as Ortho–Keratology lens, has to be worn overnight and taken off once you are awake. You can go about your work for the next 24 hours without contact lenses or spectacles as your eyesight will be temporarily restored, depending on the extent of your vision problem.
“The Ortho–Keratology lens corrects your refractive error and you can work through the day with near perfect vision. The more often you wear them, the longer you can go without lenses or glasses. If you wear CRT lenses continuously for a week, you will probably be able to see without corrective glasses for the next one week,” said Dr Vinay R Murthy, consultant, cornea and refractive surgery, at the Prabha Eye Clinic and Research Centre. The lenses, which are semi–soft, are not for all and have to be specially designed and fitted on suitable candidates. “It’s good for young people who do not want to be seen with spectacles and are not comfortable wearing contact lenses,” Dr Murthy said.
The lens, recently launched in India and available only through a few hospitals in Bangalore, is not the answer to all vision problems. It is meant for people who have low to moderate shortsightedness or myopia. It does not help those with long–sightedness (those who can see objects at a distance) and people who wear bi–focals.
The refractive correction is also limited to a maximum of – 6 diopters. Dr Veeresh from Prabha Eye Clinic, who specialises in fitting these lens, says correction is not always total and works best among teenagers for refractive errors of around –3 to –4 diopters.
How it Works
The Ortho–Keratology lenses, which costs about Rs15,000 to Rs 20,000 and can be used for a year, are based on the Corneal Refractive Therapy, a non–surgical procedure for correcting vision by reshaping the cornea. When these lens are worn overnight, they alter the curvature of the cornea and reshape them, thus bringing down the refractive error temporarily. Studies are being conducted at the All India Institute of Medical Sciences to check the effectiveness of these lenses. Some studies conducted in the West have shown that these lenses may not be suitable for children as it is known to cause infection.
A Word of Caution
It’s best to use Ortho–Keratology lenses on special occasions and events when you do not want to wear your spectacles, says Dr Rohit Shetty, refractive surgeon and vicechairman, Narayana Netralaya. “I would definitely not recommend it for long–term use as there is a high risk of infection. Moreover, wearing lens all through the night means oxygen supply to the eyes is brought down by at least 30–40 per cent.
He added that most of the studies done by either AIIMS or the Post–Graduate Institute in Chandigarh only look at short–term benefits, not long–term implications. “If worn long–term, these lenses could cause problems in the eye. I’d rather advise my patients to go in for Lasik (laser correction),” he said.