Lecture 33: Vision Problems

Question 1

What size of the pupil reduces vision?

Answer 1

Big

Question 2

What are cataracts?

Answer 2

Lens becomes cloudy

Question 3

What are corneal opacities?

Answer 3

Reduced transparency of cornea

Question 4

What is myopia?

Answer 4

Short Sighted - eyeball is too long and focal point is too early, need lenses that diverge the light to move focal point back

Question 5

What is hypermetropia?

Answer 5

Long-sighted: focal point behind back of eye, eyeball is too short, use a positive converging lens to correct vision

Question 6

What is astigmatism?

Answer 6

95% of eyes more football shaped, steep in one axis and shallow in another, only some of the light focuses in the right spot – some areas of clear vision and some areas of very blurry vision, need a cylindrical lens to correct this problem

Question 7

What is keratoconus?

Answer 7

Central part of cornea thins and becomes cone shaped, 1/2000 (70% female), associated with allergic conditions, 10% of patients require a corneal graft, give a rigid plastic contact to improve shape of eye, when lens stops working give transplant

Question 8

What are the two forms of macular degeneration?

Answer 8

Dry (90%) - retina looses cells, gradual

Wet (10%) - blood vessels invade retina and destroy it, acute

Question 9

What is the relationship of AMD and Bruchs membrane and treatment?

Answer 9

Early in AMD Bruch’s membrane thickens the nutrients cannot get into the retina. In AMD – white blobs, can be removed with nanosecond laser (just targeted to cells under photoreceptors) – makes Bruch’s membrane thinner and maintains nutrient supply to the retina

Question 10

Where does the refraction of light occur?

Answer 10

40% from lens and 60% from corneal surface