By Dr S.S. Gill
Ipoh Echo’s EYE HEALTH series continues with Consultant Eye Surgeon Dr S.S. GILL talking to us about artificial lens implants during cataract surgery.
Thanks to ophthalmologist Dr Harold Ridley (1906-2001), we have intraocular lenses today to replace cloudy cataracts during cataract surgery. A curious intern who was watching Dr Ridley perform cataract surgery asked him why he was not replacing the cloudy natural lens (cataract) that he had removed during cataract surgery. That question got Dr Ridley thinking about implanting an artificial lens intraocular lens or IOL during cataract surgery.
During World War II, Dr Ridley noticed that RAF pilots who had pieces of shattered canopy fragments which had accidentally pierced their eyes resulted in no inflammation. This made him realise that this Perspex canopy material was inert and could be used to make the artificial lens (IOL). He then embarked on implanting the first IOL in 1949 using similar material to that of the airplane canopy. The rest is history with implantations of IOL’s being routinely performed restoring vision to millions throughout the world. Once implanted the IOL requires no aftercare at all and would generally last a lifetime. A question that often confronts a patient planning for cataract surgery is “What kind of IOL should I choose?” Well, there are many varieties of intraocular lenses in the market today. They can be broadly classified as follows:
1. Monofocal IOLs
2. Astigmatism-correcting monofocal IOLs (Toric IOLs)
3. Presbyopia correcting IOLs
4. Presbyopia and Astigmatism correcting IOLs
MONOFOCAL INTRAOCULAR LENS
Photo courtesy of Alcon
These are the most commonly used type of IOL implants worldwide which have stood the test of time. The monofocal IOL is basically a single focus lens that corrects vision well. A monofocal intraocular lens cannot alter its shape to bring objects at different distances into focus. It improves vision for the distance planned preoperatively, that is, either near, intermediate or far vision. This vision is of course heaps better than seeing through a cataract! Most of the time, the eye surgeon generally selects a lens (IOL) that will provide good distance vision, and the person then resorts to wearing reading glasses for the near vision. Most patients usually just go back to wearing similar multifocal spectacles that they used to wear before the operation. A small number who may be happy with their distant vision, may just make spectacles for near reading only (presbyopic glasses).
Monovision Correction is a good alternative plan for visual correction. Here the monofocal IOL implanted in one eye corrects for clear distant vision while the IOL implanted for the other eye is corrected for near vision. This is called monovision and the patient slowly gets adjusted to seeing clearly for distance in one eye with near reading clearly in the other eye. This kind of correction requires a little patience on the patient’s part as he or she gets adjusted to the monovision correction but satisfies the visual demands of most patients. Ultimately the decision on the kind of lens to be implanted is based on the eye condition, visual demands and of course the budget of the patient.