What is cataract?
Cataract is one of the eye ailments that need screening of lens and proper medical attention. Cataract is a disease of eye lens that results in visual disturbances. In eyes, lens act as a focusing lens that pass the light to inner parts of eye. Cataract causes progressive but painless, lens opacity similar to clouding due to pathological changes in lens crystalline protein. Depending on the type and duration of disease development, it may affect the passage of light through the lens. In age-related cataract, disease process starts after age of 60 that proceeds gradually. Patients with pre-disposing factors are considered as ‘at-risk’ individuals. Usually, cataract affects one eye but it is possible to develop in another eye.
Types and causes
There are four types of cataract of which, age-related (senile) cataract is the common type. Other types of cataract are congenital, secondary and traumatic cataract. Each of these types may cause due to various factors and predispositions. In some cases, the exact cause remains unknown.
- Senile cataract – Senile cataract causes as a result of free radicals-mediated inflammation and denaturation of lens protein due to aging process. The opacity may be partial or complete depending on type of cataract. In the initial stages, senile cataract can be treated by surgical and/or medical interventions and hence complications can be prevented.
- Congenital cataract - Occurs at birth due due to various factors such as underlying genetic disorders including Turner’s syndrome and galactosemia, infections such as congenital syphilis and rubella, familial history of cataract and other birth defects.
- Secondary cataract – Occurs as a result of eye surgery for other eye diseases, certain medicines such as water-pills, steroids and haloperidol group of drugs, iodine deficiency, increased blood pressure, smoking habits, metabolic disorders such as diabetes and thyroid dysfunctions, rheumatoid arthritis, alcohol consumption, radiation rays such as X-rays, prolonged and direct exposure to UV and infrared rays, atopic allergic reactions, infections such as leprosy and toxoplasmosis.
- Trauma-induced cataract – Occurs as a result of previous accidental eye injury and/or lens damage by mechanical or shrapnel injuries.
The initial stages of disease are usually asymptomatic in nature. As disease progresses, the patient may experience abnormal visual symptoms such as opaque/ cloudy or filmy vision with halos around light objects, blurred-double vision, lack of clear vision, abnormal sensitivity to sunlight and bright light objects, impaired night vision and inability to distinguish different color shades. Most of the patients experience short-sightedness and vision changes that needs frequent visit to opticians and changing of spectacles.
Cataract can be differentially diagnosed by:
- Slit lamp examination
- Routine eye examination by using Snellen chart for vision acuity
- Eye dilation examination
- Tonometry test to rule out co-existing disorder like glaucoma.
What happen if left untreated?
Cataract can cause vision changes, inability to distinguish some colours like blue, phacomorphic glaucoma and irrevocable vision loss, if left untreated. Presence of co-existing diseases such as glaucoma or macular degeneration may worsen symptoms of cataract. Hypermature cataract is a serious complication that may occur in end-stages of untreated cataract which can be characterized by rupture of lens environment and leaking of internal fluids.
Cataract in the initial stages can be treated without surgical procedures. Some of them are: Better eye glasses with eye drops that contain azapentacene and protective sunglasses for outdoor activities can be helpful. These non-pharmacological interventions can slow-down the progression of disease process but surgery is the only treatment, if symptoms get worsen. Surgical procedure involves removal of cataract by a process of phacoemulsification, followed by aspiration of lens fluid. The subsequent process is replacement of lens with intra-ocular lens (IOL) which may be monofocal or multi-focal depending on the requirement. Surgeons prefer fewer incisions to prevent after-surgery complications and inconvenient symptoms. After surgery, antibiotics are prescribed to prevent surgery-induced infection and some patient may need eyeglasses for proper vision. These surgical procedures are common for children as well as elderly patients.
How you can prevent cataract?
Prevention is better than cure – lifestyle modification by quitting smoking and alcohol habits, protective sunglasses to avoid exposure to UV, limiting edible substance that contain lactose such as milk and other dairy products, proper treatment and medical management of metabolic disorders and infectious diseases, intake of green vegetable and fruits that are rich in anti-oxidants, nutritional supplements rich in Vitamin E & C can be helpful to prevent incidence of this eye disorder in ‘at-risk’ individuals and also in aged individuals.
Reference: Zigler JS Jr, Datiles MB III (2011). Pathogenesis of cataracts. In: Tasman W, Jaeger EA (Editors). Duane's Ophthalmology. 15thEdition. Philadelphia, Pa: Lippincott Williams & Wilkins; 72B.