Cataract

Dr. Ivan CHEN

Director, Eye Surgery Centre

Honorary Consultant in Ophthalmology

Specialist in Ophthalmology

Cataract occurs when the crystalline lens develops cloudy patches, causing blurred vision. As a natural degenerative process, it mostly happens in patients aged 60 or above, and is now becoming more common in the younger population, especially among Asians with high myopia. Cataract may also have to do with long-term use of steroids (for such conditions as eczema, psoriasis, etc.) that accelerates lens degeneration. Other causes of early onset are:

•  Diabetes
• Excessive UV exposure
• Smoking
• Imbalanced diet
• Long-term dehydration
• Eye trauma or after eye surgery, e.g. glaucoma surgery
• Congenital cataract, i.e. related to abnormal lens development during embryonic stage

Through at first not noticeable, one’s vision will get blurry when cataract continues to worsen. Other common symptoms include increased myopia, photophobia, poor night vision, etc. While it can be diagnosed at regular checkup, currently no medication is available to prevent or treat cataract. Thus cataract surgery and implantation of an intraocular lens (IOL) should be performed before the cataract becomes mature, especially when one’s vision, work or quality of life is severely affected.

The axial length, thickness and curvature of cornea are first measured with laser or ultrasound before surgery to determine the requisite type and degree of IOL. In the past, a large limbal incision was made for cataract extraction and IOL implantation. The wound was closed with very fine sutures. Nowadays cataract surgery only involves a small corneal incision of about 2mm, through which the lens is phacoemulsificated and replaced by a foldable lens. The wound can heal itself and usually requires no suture.

From Therapeutic Surgery to Refractive Surgery 

Starting as a therapeutic surgery for cataract, IOL implantation can now correct vision by treating myopia, hyperopia, astigmatism and presbyopia.

Doctors will discuss with patients and choose the most appropriate IOL based on their lifestyles and needs before surgery. Patients may still need to wear glasses or contact lens after surgery to correct the remaining refractive errors.