Often found in older people, cataract is a condition that causes clouding of the eye.
What is cataract?
Cataract is a common eye condition that affects the lens (which cannot be seen as it is behind the pupil or central black spot).
What is the lens?
The lens is a transparent bi-convex structure covered by a capsule and held in position by a suspensory ligament. The lens has a central nucleus surrounded by a cortex. It’s function is to absorb the light rays and focus them on the retina.
Any opacification (process of becoming opaque) of the lens or its capsule, whether partial or total, is termed as cataract.
The most common type of cataract is called Senile Cataract. As we age, the proteins in the lens begin to break down and the lens becomes cloudy, causing the vision to become blurry. Cataract changes are generally seen when a person reaches the age of 70.
It occurs equally in both sexes and generally in both eyes, one later than the other.
Signs and symptoms of cataract:
- Deterioration of far and near vision which is painless.
- Diplopia or double vision.
- Black spots in front of the eyes.
- Decreased visual field in the periphery.
- Coloured halos and night glare while facing car headlights.
- White opacity inside the pupil – generally noticed by others.
- Long-standing cataract may give rise to complications like glaucoma, spread of inflammation and no perception of light (PL).
Causes of Cataract:
- Old age – advancing years can cause cataract.
- Congenital or developmental – also called Buphthalmos.
- Traumatic – due to injury by a sharp or blunt object, electric shock and radiation.
- Secondary – due to diabetes mellitus or other systemic conditions.
- Complicated – due to other eye conditions like retinal detachment or high myopia.
- Toxic – as a side effect of drugs like steroids.
Treatment of cataract:
Once cataract develops, the process cannot be reversed. Also there is no way to prevent the onset or progress of a cataract. Therefore, surgery is the main form of treatment. After the lens is removed, an artificial lens is inserted in the same position. Surgery is indicated when vision impairment prevents a person from carrying out his day-to-day activities. Surgery is also carried out when the presence of cataract affects the health of the eye or rarely for cosmetic reasons to get a black pupil. Before surgery, detailed ocular investigations are carried out to detect any co-existing conditions, calculate the power of the lens to be inserted and to prevent complications post-surgery.
Types of Surgery:
Broadly, cataract removal can be done by Extra-Capsular Cataract Extraction (ECCE) or Intra-Capsular Cataract Extraction (ICCE) followed by Intra-Ocular Lens (IOL) implantation.
IOLs generally weigh 2-3 mg and are 2mm thick circular or oval in shape. They are made up of polymethylmethacrylate (PMMA), polypropylene or a silicon polymer. According to the specific symptoms of each patient and skill of the surgeon, they can be placed in 4 different places in the eye but the commonest is the posterior chamber IOLs. In rare cases like a one-eyed patient, IOL implantation is contra-indicated.
To conclude, cataract is a common eye condition. We have mainly featured senile cataract, which is most common and naturally occurring. Cutting edge surgery has ensured that most people lead a relatively good quality of life but as with any procedure there is a minimal risk of human error and post-operative complications.
Written by Dr Nisreen Nakhoda, General Physician
Photograph by Rakesh Ahuja, MD, via Creative Commons
