Ask The Experts

Two ways to correct 'lao hua'

GRAPHIC: COURTESY OF NATASHA LIM
GRAPHIC: COURTESY OF NATASHA LIM

Q I have just turned 50 and reading is getting more difficult. Are there any permanent treatments for presbyopia?

A Muscles which control the crystalline lens inside an eye automatically relax when we look at faraway objects and contract when we look at small objects close up. This enables the lens to provide the correct focusing power for far and near vision.

When a person is around the age of 40, the muscles within the eyes start to weaken in their ability to contract and expand the lens, losing focus for near objects.

Moving your reading material further away from your eyes can help as it adjusts the focus point of your eyes.

Around the age of 50, the lens start to develop early cataract changes, becoming cloudier and inelastic.

The combination of weakened muscles and inelastic lens makes reading glasses a requirement at this age.

Many people with presbyopia ("lao hua") still wish to enjoy all the five zones of human vision (see graphic, right) without spectacles.

The first option is mono-vision, using Lasik surgery to correct one eye's focus for far vision (Zones Four and Five) and correct the other eye's focus for near vision (Zones One and Two).

The brain then merges the two images, producing "blended vision" to achieve intermediate vision (Zone Three), thus enabling you to see relatively well at all distances.

To make sure you can adapt to this kind of vision, you would experience mono-vision with simulation lenses at the clinic before having a more permanent surgical procedure.

Lasik mono-vision does not prevent cataract formation.

By the age of 60, everyone with or without past Lasik experience would likely face blurred vision caused by cataracts and may require cataract surgery.

Normal cataract surgery can be performed in post-Lasik eyes and the new lens implant inserted during cataract surgery can correct presbyopia once again.

Your second option is cataract surgery and lens implantation. It is a one-time procedure without the need for repeat cataract surgery.

Refractive cataract surgery replaces a cloudy lens with a multi-focal lens implant to correct presbyopia.

Associated short-sightedness, long-sightedness and astigmatism are also treated completely, allowing you to be spectacle-free for all five zones of vision. This is a 15-minute, pain-free procedure.

Both options may cause a slight drop in the quality of distance vision, but it is not visually debilitating.

Many people feel it is a worthwhile trade-off in order to enjoy life without using spectacles and retain near vision after middle age.

Dr Natasha Lim

Medical director at Dr Natasha Lim Eye Centre at Mount Elizabeth Novena Hospital

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A version of this article appeared in the print edition of The Straits Times on November 01, 2016, with the headline 'Two ways to correct 'lao hua''. Print Edition | Subscribe