Eye Physiology

Question 1

What 3 things happen during accommodation?

Answer 1

1. Ciliary muscles contract
2. Pupil constricts
3. Eyes Converge

Question 2

What happens when the ciliary Muscles contract?

Answer 2

Suspender ligaments relax, Lens becomes more spherical, Light refraction becomes stronger

Question 3

What happens when the Pupil constricts?

Answer 3

Sphincter pupillaes are activated, Parasympathetic fibres activated by Cr. N 3

Question 4

What happens when pupil converges?

Answer 4

Medial rectus muscles activated by Cr N 3 parasympathetic

Question 5

What is Myopia, what causes it?

Answer 5

Myopia is shortsightedness,
This is due to the lens not being able to refract light enough and the light arrives infront of the retina. In other words eye is too long

Question 6

What are the symptoms of Myopia, and how would you treat it?

Answer 6

Symptoms: 
Unable to see far away writing, Headache, Children have less focus in class
Treatment:
Biconcave lens
Laser eye surgery

Question 7

What is Hyperopia?

Answer 7

Hyperopia is longsightedness, Light refracting behind the retina due to not enough refraction power, Accommodation been exhausted so not any left

Question 8

What are the symptoms of Hyperopia and how do you treat it?

Answer 8

Symptoms: Strain when reading, convergent squint
Treatment: Convex lens, Laser eye surgery, spectacles

Question 9

What is astagmatism?

Answer 9

Astagmatism is when the the lens has a different curvature when it should do meaning in light bending in differnt angles, resulting in multiple focal points around the retina rather than just one

Question 10

Symtoms of astagmatism?

Answer 10

Symptoms: Image appears hazy, headahce
Treatment: Toric (Cylindrical) lens, Laser eye surgery

Question 11

What is Presbyopia, and what causes presbyopia

Answer 11

Presbyopia is just hyperopia but due too old age, Lens becomes more elastic, resulting in less curvature and hence the light refracts behind the lens

Question 12

Describe the afferent tract due to light reflex

Answer 12

When light falls on the eye, the fibres dont travel back to the LGB , they go back to the Edinger-Westphal nuclues which cause the pupil to constrict

Question 13

Describe the efferent tract of the light relex

Answer 13

The Edinger-Westphal nucleus sends out an impulse through the parasympathetic fibres of the 3rd Cranial nerve causing the constriction of pupils