The senses - pathology & diseases for the sense of sight - ch 13

Question 1

Name 10 diseases of the sense of sight?

Answer 1

1. astigmatism
2. blindness
3. cataract
4. glaucoma
5. macular degeneration
6. nystagmus
7. retinal detachment
8. retinobalstoma
9. strabismus
10. trachoma

Question 2

Whats the definition of astigmatism?

Answer 2

astigmatism occurs when the refractive surface of the cornea or lens is abnormally curved. Light rays cannot focus sharply on the retina causing vision to be out of focus. Astigmatism frequently occurs with other vision conditions like myopia and hyperopia

Question 3

What is the definition of blindness?

Answer 3

Refers to a partial or complete loss of vision. It may also refer to a loss of vision that cannot be adequately corrected with glasses or contact lenses. Partial blindness means a person has very limited vision. Complete blindness means a person cannot see anything and is also unable to perceive light. The leading causes of blindness among Australians are macular degeneration, glaucoma, cataracts and diabetes.

Question 4

What is the definition of a cataract?

Answer 4

A cataract is a degenerative eye condition characterised by a clouding or opacity of the lens or the lens capsule. It is a common cause of gradual vision loss. Light shining through the cornea is blocked by the clouded lens - the image cast onto the retina is blurred, therefore the brain interprets a hazy image. There are many different types of cataracts such as; senile, congenital, traumatic, complicated, toxic and diabetic.

Question 5

Name 6 symptoms of a cataract?

Answer 5

1. cloudy vision
2. blurry vision
3. faded colours
4. sensitivity to glare
5. halo appearing around lights
6. poor night vision

Question 6

How is a cataract fixed?

Answer 6

Usually surgically removed and a replacement lens is inserted.

Question 7

What is the definition of glaucoma?

Answer 7

Glaucoma is an eye disease in which the optic nerve at the back of the eye trophies. In most people this damage is due to raised intraocular pressure due to problems with the drainage of the aqueous humour. Damaged progresses very slowly and destroys vision gradually starting with peripheral vision.

Question 8

What is the most common type of glaucoma?

Answer 8

Chronic (primary open-angle) glaucoma is the most common.

Question 9

Are there any symptoms of glaucoma?

Answer 9

No real symptoms until eyesight is lost at a late stage. It can lead to blindness if not treated.

Question 10

what is the definition of macular degeneration?

Answer 10

A progressive deterioration of the macular tissue of the retina leading to a loss of central vision affecting the ability to see fine detail, drive, read and recognise faces.

Question 11

Is macular degeneration related to age?

Answer 11

Yes, can be

Question 12

what is a symptom of macular degeneration?

Answer 12

A spot may appear different for each eye. It is the visual acuity which is most affected.

Question 13

Name the two types of macular degeneration?

Answer 13

1. dry atrophic from

2. wet neovascular form

Question 14

What is the dry form of macular degeneration caused from?

Answer 14

slow deterioration of the macula, resulting in a gradual blurring of central vision. Spots called drusen located on the outer retina are the key identifiers for the dry type.

Question 15

Do most people with age-related macular degeneration begin with the dry form.

Answer 15

Yes

Question 16

Describe the wet form of macular degeneration?

Answer 16

newly created abnormal blood vessels develop in the centre of the retina. These blood vessels can leak and scar the retina, damaging central vision. Vision loss may be rapid in the wet type of macular degeneration

Question 17

What is the definition of nystagmus?

Answer 17

Involuntary thythmical movements of the eyes, also known as ‘dancing eyes’. Nystagmus causes blurred vision because the eyes are always moving. In some people with the condition, head posture is also affected because the eye movements reduce in particular positions. The condition may be unilateral or bilateral, and may be congenital or acquired.

Question 18

Is there a cause of acquired nystagmus?

Answer 18

No, but maybe due to central nervous system or metabolic disorders or alcohol and drug toxicity.

Question 19

What is the definition of retinal detachment?

Answer 19

retinal detachment occurs when the retina separates from the supporting layer, the choroid, resulting in loss of vision.

Question 20

Name 4 causes of retinal detachment?

Answer 20

1. Infection
2. haemorrhage
3. injury
4. ageing

Question 21

What can retinal detachment often be associated with?

Answer 21

a tear or hole in the retina through which the vitreous humour may leak. If not treated the detachment can lead to blindness.

Question 22

what is the definition of retinoblastoma?

Answer 22

retinoblastoma is an aggressive malignant tumour arising in the retina. It mostly affects children under 5 years of age. It can either be unilateral (75%) or bilateral (25%) and hereditary is a factor in about 10% of cases.

Question 23

What are the signs of retinoblastoma?

Answer 23

mass of white tissue, leucocoria (reflection from a white mass within the eye), visible through the pupil. The eye will be inflamed and the eyeball will appear enlarged. Strabismus (eyes do not point in the same direction) may be present. Irides (plural of iris) may be heterchromic (a chronic inflammatory cyclitis in which the iris of the affected eye becomes atrophic). As it grows, a retinoblastoma can spread to the orbit and along the optic nerve to the central nervous system.

Question 24

Can retinoblastoma be a fatal condition?

Answer 24

Yes it can if not treated.

Question 25

How is retinoblastoma classified?

Answer 25

By the number of tumours (single or multiple), the size of the tumour and spread (or not) into surrounding tissue.

Question 26

What is the definition of strabismus?

Answer 26

strabismus occurs when the eyes are not able to focus in the same direction at the same time. One eye is misaligned in relation to the other when focusing on an object. It is most commonly due to a weakness of the extraocular muscles.

Question 27

There are four main types of strabismus, name them?

Answer 27

1. Estropia - is an inward turning
2. exotropia - is an outward turning
3. hypertropia - is an upward deviation
4. hypotropia - is a downward deviation

Question 28

What is the definition of trachoma?

Answer 28

Trachoma is a chronic contagious infection of the conjunctiva caused by chlamydia trachomatis bacterium. It occurs mostly in rural setting in developing countries where standards of hygiene are poor.

Question 29

How is trachoma spread?

Answer 29

Through direct contact with infected eye, nose or throat secretions. Contact with contaminated objects, such as towels or clothes can also spread the disease.

Question 30

Name 4 symptoms of trahoma?

Answer 30

1. pain
2. photophobia
3. excessive lacrimation
4. presence of granulated lesions

Question 31

Can trachoma lead to blindness if not treated?

Answer 31

If not treated yes