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Chapter: 11th 12th standard bio zoology Human Body higher secondary school

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Human Eye : Glaucoma, Nyctalopia Disorder, Infections, Symptoms, Treatment

Glaucoma is a serious disorder of the eye and is a common cause of blindness. Increased IOP (Increased Occular Pressure) compresses the optic nerve at the optic disc with degeneration of optic nerve fibres and cupping of the optic discs with progressive loss of visual acuity starting with peripheral vision.

Glaucoma

 

Glaucoma is a serious disorder of the eye and is a common cause of blindness. Increased IOP (Increased Occular Pressure) compresses the optic nerve at the optic disc with degeneration of optic nerve fibres and cupping of the optic discs with progressive loss of visual acuity starting with peripheral vision. The retinal artery which enters the eye ball at the optic disc

is compressed causing retinal degeneration. In most cases the cause of glaucoma is unknown but in some cases it may be due to infection or trauma in the eye. When the IOP is very high (50-70 mm Hg) blindness occurs within few days.

 

Nyctalopia

 

Vitamin A is necessary for resynthesis of visual purple. Nyctalopia or night blindness is the first sign of vitamin A deficiency. Prolonged deficiency of vitamin. A leads to degenerative changes in rods and cones and nervous layers of the retina. Administration of vitamin A before degenerative changes occur will restore retinal functions. Normal retinal function also requires the presence of optimal amounts of other vitamins especially the B complex just as other nerve tissues do.


Infections

 

1. Stye : A stye is an acute infection of the glands located at the eyelid margin. There is swelling, pain, itching and redness in a small area at the lid margin. Treatment consists of using frequent warm compresses on the eye.

 

2.  Conjunctivitis: Infection in the conjuctiva is called conjunctivitis. Due to the infection the invisible blood vessels within the conjunctiva become engorged. Inflammation of the conjuctiva causes redness, discomfort and a

 

discharge from the affected eye. The most common causes for conjunctivitis are infections (in children) and allergy (in adults).

 

2a. Infective conjunctivitis : Most conjunctival infection are caused by bacteria (e.g staphylococci) and are spread by hand-to-eye contact or by viruses associated with a cold, sore throat, or illness such as measles, viral conjunctivitis sometimes occurs in epidemics, spreading rapidly through schools and other groups.

 

2b. Allergic conjunctivitis : An allergic response of the conjunctive may be provoked by a variety of substances including cosmetics (mascara), contact lens cleaning solution and pollen.

 

Symptoms : All types of conjunctivitis cause redness, irritation, itching, discharge and occasionally photophobia (abnormal sensitivity to bright

light). In infective conjunctivitis the discharge contains pus and may cause the eyelids to be stuck together in the morning. In allergy conjunctivitis the discharge is clear and the eyelids are often swollen.

 

Treatment : Warm water is used to wash away the discharge and remove any crust on the eyelid. Infections are treated with eye drops or ointment containing an antibiotic drug. Allergic conjunctivitis may be relieved by use of eye drops containing an anti histamine drug.


Eye care

 

Eye is an important organ and it is to be taken care of.

 

1.Eye examination should be periodically done to determine the cause of visual disturbance or other symptoms relating to the eye.

 

2.                Foreign particles in the eye are very common and it may penetrate in the eye ball. So care should be taken while removing the dust to avoid damage.

 

3.                The retina should be periodically examined to assess conditions such as hypertensive retinopathy for hypertension and diabetic patients.

 

4.                Self medication should be avoided. A doctor should be consulted immediatly if there is any sudden pain or blurry vision.


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