Top 5 Causes of Blindness

Our eyes perform the important function of using its vision to help us navigate through our daily lives.



Eyes are a window meant for all of us to see and perceive this world as we like. Our eyes perform the important function of using its vision to help us navigate through our daily lives. They provide the brain with visual feedback and protect us from any potential harm.

Unlike other life forms who can see the world only in monochrome, we humans (and primates) are blessed with a color vision to admire beauty in all ways and forms. It is important that we understand the importance of eyes and take very good care of them instead of taking them for granted.

The World Health Organization or WHO is a government body concerned with the betterment of health issues worldwide. In a survey conducted by WHO earlier, it was estimated that –

  • About 289 million worldwide are affected by some form of visual impairment out of which 39 million people are blind.
  • 90% of these visual impairments are a result of chronic eye diseases.

We have often seen our grandparents complaining of difficulty in seeing things, foggy eyes and spots in their vision. Many of our diabetic relatives too are disturbed with impaired vision.

An interesting fact is that, a vast majority of these diseases are preventable if detected at the right time or if healthy lifestyles have been adopted.

The leading causes of blindness outlined by WHO are as follows:

Cataract

Accountable for about 47% of visual impairment worldwide, cataract is an age related disease which if not treated on time can lead to partial or total blindness.

Cataract is an eye disease characterized by foggy vision, increased glare, poor visibility in low light conditions/night, inability to detect colors properly and decreased contrast level of vision.

Our eyes are made up of a clear lens like structure which are made up of special proteins. These lens are responsible for transmitting light gathered from outside onto the retina. Sometimes this lens opacifies (or becomes cloudy) because of

  • Hardening of central lens material
  • Change in structure of lens protein (crystallins)
  • The lens proteins get pigmented (yellow-brown)

Apart from age, other causes of cataracts include diabetes, smoking, ocular diseases, prolonged steroid use, eye trauma and genetics.

The good news is that, cataracts are very much treatable with the help of a simple out-patient procedure known as cataract surgery. It is performed by a certified eye surgeon who makes tiny incisions in the eye lens to take out the cloudy lens material with the use of an ultrasonic probe. Once the cloudy material has been aspirated or sucked out, a new intra ocular lens is implanted in place of the original one. Cataract surgery is a very safe procedure with high success rates. It is performed under local anesthesia.

Age Related Macular Degenration (AMRD)

The macula is an important part of the retina responsible for focused or ‘keenest’ vision. Think of it as a spot which gives you a picture with high definition – HD. Age related macular degeneration is among the common causes of visual impairment and blindness in the western countries.

AMRD presents in the form of distorted vision, missing areas of vision, decreased visual acuity, blurred vision, low contrast sensitivity and difficulty in distinguishing different colors.

Macular Degeneration exists in two forms:

Dry form  

This makes up majority of AMRD cases. It is characterized by formation of white or yellow deposits on the retina known as drusen. It is also known as the atrophic variety of macular degeneration.

Wet form

Known as the exudative form of macular degeneration, this form is characterized by formation of an abnormal number of blood vessels beneath the macula. These blood vessels are very fragile in nature and rupture pretty easily, leading to leakage of blood and proteins, followed by scarring and damage to photoreceptor cells.

The sad thing about macular degeneration is that it is usually asymptomatic in early stages and once it reaches in an advanced stage, it is an incurable malady. Presently, no specific cause has been determined for macular degeneration, but things like genetics and smoking puts people at more risk of AMRD. If not treated in time, AMRD can be declared as legal blindness after a period of 6 months.

Laser coagulation and photodynamic therapy have been found to be somewhat effective in preventing further degeneration, but it is of little value in the long run.

Glaucoma

Glaucoma is an eye disease which happens because of steady buildup of intra ocular pressure.

Our eyes consist of a special fluid known as vitreous humor and aqueous humor. These fluids prevent the eyes for drying out and are an important source of nutrition to the eyes. To keep the eyes healthy, the aqueous humor constantly circulates and renews itself by draining itself out from the eyes via a mesh like structure. Now sometimes, due to some sort of blockage in the mesh or any other structure, the aqueous humor is unable to drain itself out properly. This causes pressure buildup in the eyes resulting in a subsequent pressure on the optic nerve.

The compression of optic nerve will result in failure of transmission of image signals to the brain, hence a loss in vision.

Glaucoma is of two types –

  1. Open angle glaucoma
  2. Closed angle glaucoma

Glaucoma shows itself in the form of headache, eye pain, blurred vision, halos and loss of peripheral vision. Early glaucoma is usually asymptomatic and not detected easily. It is best to go for regular eye check ups every year or two.

Glaucoma is a treatable condition if caught early. Untreated glaucoma can permanently compress the optic nerve leading to loss of vision. Presently, glaucoma can be managed both by medications, laser surgery and microsurgery.

Diabetic Retinopathy

Diabetes is a silent stealer of light. Both type 1 and type 2 diabetics are highly susceptible to retinopathy.

Blurred vision, difficulty in night vision, spots in vision and loss of central vision are its signs and symptoms.

High amounts of sugar are present in the blood which slowly start to accumulate in different parts of the body. Even the blood vessels are not spared from this sugary onslaught. Diabetic retinopathy is of two types:

Early diabetic retinopathy

Here there is only weakness of tiny blood vessels which supply the retina. These vessels grow leaky over time and dilate in the form of aneurysms. This in turn damages the retina and degeneration of vision.

Advanced diabetic retinopathy

Also known as proliferative diabetic retinopathy, here damage of tiny retinal blood vessels triggers formation of new blood vessels around the retina which slowly damage it and cause retianl detachment.

Diabetic retinopathy can be treated via a laser surgery.

Corneal Opacities

Corneal opacity is not a single entity, rather it is a group of diseases which can lead to opacification of the cornea. The cornea is a clear transparent structure which covers the eyes. The cornea is a structure which is capable of handling minor injuries to the eyes, but any condition of more severity can render it weak and result in corneal scarring.

Causes of corneal opacities are:

  • Congenital (since birth)
  • Metabolic storage diseases
  • Dermoid
  • Trauma
  • Infections such as keratitis
  • Herpes Simplex Virus infections
  • Bacterial infections

Often corneal opacities show up as redness & swelling of eyes, blurred vision, eye discharge, photophobia (sensitivity to light), milky areas in the cornea and subsequent vision loss.

Corneal opacities can be best treated if their underlying cause is diagnosed well. Most of these causes can be treated well with surgeries and corneal transplantation in some cases. After the surgery, the resultant refractive errors can be managed well with spectacles or contact lenses. Other symptoms such as photophobia can be well treated with medications & eye drops.

Apart from these, other prevalent causes of blindness include:

  • Childhood Blindness
  • Onchocerciasis (River Blindness)
  • Eye/Ocular Trauma
  • Leprosy

Our eyes and vision should never be taken for granted. Since most of these eye diseases are preventable, blindness and visual impairment can be kept at bay if proper care is taken. Today the treatment solutions available for eyes are minimally invasive in nature and are performed on an outpatient basis, meaning you can return your home safely soon after the procedure has been performed.

Conditions like cataract surgeries have a high success rate and significantly improves the quality of life of an individual. Intra ocular lenses are available with a fixed (unifocal) or variable (multifocal) focal lengths to enable better vision.

Regular eye check ups, proper & safe care and healthy lifestyle modifications are always beneficial in the long run.


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