Introduction To Cataract

The eyes , the most sensitive , the most delicate , the most reliable source of information for mind. Thus it's highly important to have a good vision.

Light enters the eye through a small hole called pupil and is focused on the retina . Eye has a lens that focuses images on retina .This lens is transparent and to see through clearly it is important for this lens to remain transparent , any kind of opacity effects vision .The crystalline lens, through which light travels into the interior of the eye, is situated just behind the iris, or coloured portion of the eye. In cataract, this lens becomes opaque, seriously hampering the entrance of light into the eye. Blindness ensues when no light rays can permeate the opacity of the lens.

Early Cataract Symptoms

The cataract of early stages can be rectified by the use of spectacles , sunglasses etc. But in advanced stages cataract may grow to a visible stage which causes great changes in vision .

Cloudy Blurry vision

Colours seem faded , unable to distinguish colours.

Bright light glare specially while driving

Double Vision

Advanced Cataract Symptoms

In the advanced stages of cataract ,eye lens becomes  visibly cloudy and white . This is the stage when cataract is visibly mature and a stage when treatment should commence .

Factors leading to cataract

Age

Diabetes

Family History

Eye surgery

Prolonged use of steroids

Sunlight exposure

smoking

Types of cataract

Etiology Based

1) Senile Cataract / Age related Cataract

2) Congenital Cataract

3) Secondary Cataract

1) Senile Cataract

Senile cataract is cause either due to protein clumping or due to lens discolouration , which is the initial opacity of lens which further may lead to complete opacity no disc view  , this advanced stage is called Morgagnian Cataract.

Senile Cataract further can be classified into

IMSC ( Immature Senile Cataract ) in which the opacity is partial and has hazy disc view.

MSC ( Mature Senile Cataract) in which the opacity is full and there is no disc view.

HMSC ( Hyper Mature Senile Cataract)  in which it is in its advanced stage and is called Morgagnian Cataract

Senile  Cataract due to protein clumping

The lens in the eye is made up of protein and water which allow the light to pass through and enable us to see , With age lens undergoes many changes which also change the  structure of protein fibres , due to which some of the protein fibres start to clump together giving cloudiness in small areas initially , which later may advance to the larger area of the lens.

Senile Cataract due to lens discolouration

Lens discolouration is different from opacity . In this the vision gets a brownish tint .In initial stages it does not effect day to day working but may effect vision to greater extent , specially in the identification of blue and purple colours

2) Congenital Cataract

Cataract present at or after birth is called Congenital Cataract . If cataract is developed in child after birth , then child may complaint about difficult focusing or may tilt his head to view or may develop a squint. Congenital Cataract can be due to infections , metabolic disruption , ocular abnormalities , trauma , prematurity , family history of Congenital Cataract , genetic causes like Downs  syndrome

Few commonly occurring types of Congenital Cataract

Anterior Polar Cataract , which is due inherited cataract and is present in front of the eye lens

Posterior Polar Cataract , which is present at the back portion of the lens

Nuclear Cataract , which is present in the central portion of the lens

Cerulean Cataract , which is present in both the eyes of the infant and small bluish dots are visible on the lens

Congenital Cataract should be given utmost importance and care. In our visual system eye is the one on which brain relies fro all information . The eye and the brain communication develops by the age of 7 .In children if one eye is weak and one works properly , then brain receives both good and bad (blurry or improper)  images. The brain starts accepting and learning the good ones from the perfect eye and starts ignoring the improper ones sent by the weak eye , which may result in the permanent loss of vision from weak eye as stops using that eye at all in the long run . This is known as lazy eye or Amblyopia. Bilateral cataracts can cause amblyopia to develop in both the eyes.

3) Secondary Cataract

This is the kind of cataract which occurs neither due to age nor due to any inheritance .This may occur due to external factors like , surgery , diabetes , overuse of steroids , trauma (like hit by some sharp or blunt thing) , electric shock etc.

Location based

1) Nuclear

2) Cortical

3) Subcapsular

1) Nuclear Cataract

This cataract occurs in the centre of the lens. The person may become short sighted , sometimes get better reading vision. In this the lens turns yellow or even brown. The patient has difficult vision in dim light and night driving. In advanced stages it becomes difficult to differentiate between blue and purple.

2) Cortical Cataract

In this type of cataract pt gets whitish , wedge shape on the outer surface of the lens .It may extend to centre causing disruption in light .Patient has glare problems.

3)Subcapsular

There is small opacity under the lens or on the back side of the lens .Patient gets poor Reading vision, has difficulty in bright light , glare and at night .

Diagnosing Cataract

Diagnosis can be easily made by an eye checkup .One can easily get the Early signs of cataract by seeing the opaque and grayish white thing on the pupa. Ophthalmologist clinically diagnosis it clearly by using any of the following methods    

Visual Acuity Test

Dilated pupil examination

Tonometry

Slit Lamp Examination

Ultrasonography

Apart from above tests regular eye checkups , blood pressure and sugar level tests and sometimes conjunctiva discharges may be done to rule out any bacterial infection.

Cataract	Glaucoma	Diabetic Lens Osmosis	Corneal Dystrophy's
· Most Common · Gradually destroys the central vision · Difficulty in reading and driving · Grows very slowly so has Little effect	·  Pressure in eyes ·  Pressure damages the main optic nerve. ·  Patient losses sight from sides.	·  The ocular Lens gets filled with fluid due to high blood pressure	· Eye pain which is absent in Cataract · Visual impairment