WHAT IS CATARACT?
Cataract is the leading cause of blindness worldwide and note that it's reversible unlike glaucoma which isn't reversible. It's simply called white blindness because a portion of your eye looks white which in medical term is known as opaque.Just as the heart and kidneys are important,the eye is very very important.Sudden or gradual vision loss causes a lot of psychological stress as we have to adjust our lives and make choices to suit our loss of vision.
Cataract simply means opacity of the lens.The eye has cornea and behind the cornea is the iris which gives the colour of the eye.Most people have black coloured iris so we say the eye is black.The iris has an aperture in it forming the pupil and behind the pupil is the lens of the eye.It is this lens which becomes opaque in cataract.The lens is a refractive medium,that is,it allows light rays to pass through to the back of the eye(retina).This allows us to see.If the lens becomes opaque,that means light rays can't pass through and we therefore can't see. People with cataract often complain of blurry vision.
CAUSES AND TYPES OF CATARACT
Some cataracts are congenital,that is,you're born with it.Others too are acquired.Things that will cause your baby to be born with cataract include a malnourished pregnant woman,thalidomide ingestion,radiation exposure and down syndrome.Congenital cataracts are operated upon by paediatric ophthalmologists.Such children are given contact lenses after surgery and they are then managed for amblyopia or lazy eye.
Acquired cataract may be caused by
Aging:people in their 6th and 7th decades are likely to present with cataract
Eye diseases:uveitis,diabetes.Note that diabetes increases your chances of getting cataract especially when your sugar level goes high and if you are diagnosed with diabetes in your early stages of life.
Metabolic diseases:Galactosaemia and manosidosis
Trauma:road traffic accidents,penetrating eye injuries
TREATMENT OF CATARACT
Main treatment is surgery.This is to change the lens in the eye;the lens is replaced with an artificial lens.People may opt for surgery for cosmetic reasons and others for health reasons.Before and after surgery,patient may be given a spectacle to protect the eye from ultraviolet rays.
GLAUCOMA
This is the second leading cause of blindness worldwide but the first cause of irreversible blindness in the world.Most people think glaucoma means there is high pressure in the eye.To an extent,this may be true.Glaucoma is actually a heterogeneous group of diseases affecting the optic nerve which causes a specific visual field defect or loss.Unlike cataract,glaucoma runs in families so if a relative especially a first degree relative has glaucoma,there is a higher probability that you may also have glaucoma someday.
RISK FACTORS FOR GLAUCOMA
1.Positive family history of glaucoma
2.Black race
3.High intraocular pressure:This is mostly determined by your eye doctor or ophthalmologist.
HOW GLAUCOMA OCCURS?
Your eye has ciliary muscles and ciliary processes which function in accommodation.The ciliary processes also make aqueous humour,a clear fluid into the posterior chamber of the eye,that is,between the lens behind and iris infront.The aqueous humour flows through the pupil to the anterior chamber(between the iris behind and cornea infront).From the anterior chamber,the aqueous humour flows through the angle at the trabecular meshwork into the episcleral veins.If for whatever reason,there is a blockage to the flow of aqueous,it builds up in the eye and raises the pressure in the eye.This is the commonest cause of glaucoma.
SYMPTOMS
Glaucoma is generally asymptomatic in the early stages.In the late stages,patient may complain of loss of peripheral vision or tunnelling of vision with eventual blindness,poor visual acuity and reduced colour and contrast sensitivity.
TREATMENT
This is either medical or surgical.In surgical method,surgery is performed to allow the aqueous humour of the eye to drain in cases of high intraocular pressure.Medical treatment involves:
1.Administration of beta blockers like atenolol to reduce production of aqueous humour from the ciliary processes.
2.Administration of parasympathomimetics like pilocarpine to improve uveoscleral outflow
3.Administration of systemic drugs like intravenous mannitol to dilute the aqueous humour.
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