What is cataract?

Cataract is a pathological condition of the eye as a result of the crystalline lens, present inside the eye, becoming cloudy and opaque. It is the leading cause of blindness in India.

Etymology

The word “cataract” literally means waterfall. In Latin, the word cataracta means a sudden gush of water (a waterfall). In medical terminology, it is a term given to the condition where the lens in the eye becomes cloudy so that the person feels as if he/she is trying to see through a waterfall. The clouding of the lens is essentially the clumping of the protein material which makes up the lens.

Causes

• Aging
• Certain diseases such as diabetes mellitus or eye-trauma.  
• Vitamin or other deficincies in children.
• Heridity  

Symptoms

Cataracts tend to develop slowly, hence there would be no sudden change in vision. The vision slowly becomes blurred as the lens gets misty and turns opaque. This opacity of the lens may make it difficult even to comfortably recognise people. Other symptoms may include:

• Glare or light appearing too bright
• Poor night vision
• Increased change in nearsightedness
• Fading colours

Types and classification 

Cataracts (spots of cloudiness) may range in size from small to large.  They may be graded as mild, moderate and significant depending on the severity and extent of opacity of the lens.

Cataracts can also be categorised depending on the cause or the location of the defect.

Depending on the cause:-

♦ Senile cataracts:         Due to old age

♦ Congenital cataracts: Due to birth defects

♦ Juvenile cataracts:     Due to vitamin/mineral deficiencies in children

♦ Secondary cataracts:  Due to presence of other diseases

♦ Traumatic cataracts:   Due to eye-trauma.

Depending on the location:-

♦ Nuclear cataract: This is the cataract which develops at the center of the lens. The middle portion of lens appears cloudy and is the most common type of senile cataracts.

♦ Cortical cataract: This type of cataract develops as wedge-shaped spokes extending from the outside of the lens to the center. The outer portion usually turns cloudy and it is commonly seen in diabetic patients.

♦ Posterior Subcapsular cataract: Also a secondary cataract, this type of cataract starts at the back of the lens, the surface of which would be similar to grounded glass. This then progresses slowly and covers the whole lens.  

Diagnosis

The presence of cataract is diagnosed by dilating the pupil with eye-drops and then examination of the interior of the eye by a slit-lamp.

Treatment

If the cataract is in an early stage, different eye-glasses or a magnifying glasses are prescribed. At advanced stages, surgical intervention is inevitable. The widely-used treatment is the removal of the affected lens and implantation of an artificial lens behind the iris. Phacoemulsification is the common technique used for lens removal where a small incision is made on the side of the cornea. The lens is broken up using ultrasound vibrations and then removed by suction. A new silicone foldable lens, is later implanted in its place. In case, the lens cannot be inserted, the patient may have to wear eye-glasses or contact lens.

If the cataracts are present in both the eyes, treatment would be done for one eye at a time with a space of 3-4 days. 

After-care

The operation takes just 20-30 minutes and the patient can be discharged immediately afterwards. He/She is advised to take rest at home for a couple of days.  Eye drops are usually prescribed which may be accompanied by tablets to be taken for some time.

Preventing cataracts

Although cataracts cannot be completely prevented, the onset of cataracts can be delayed significantly by avoiding the following:

--Smoking

--Overexposure to the UV rays of the sun