Opt. - Lec 3b - Common Disorders Of The Eye

Question 1

Epidemiology of:

Cataract

Answer 1

18 million people blind with this condition
= 48% of all blindness
Ranges from 5% to 50% in affluent and poorer regions respectively

Question 2

Epidemiology of:

Glaucoma

Answer 2

4.5 million people go blind with this condition

Question 3

Epidemiology of:

Age related macular degeneration

Answer 3

3 million people go blind
9% of all blindness

Commonest cause of blindness in industrialised countries

Question 4

Epidemiology of:

Diabetic retinopathy

Answer 4

1.8 million people go blind (5% of all blindness)

0% in Africa to 17% in America and Europe

Question 5

What structural changes are involved in cataract formation?

Answer 5

Enzymatic control of water uptake fails - incoming water forms vacuoles and ruptures membranes

Question 6

What metabolic changes are involved in cataract formation?

Answer 6

Activity of anti-oxidants and enzymes reduces

Question 7

What molecular changes are involved in cataract formation?

Answer 7

Oxidation damages lens proteins

Crystalline become insoluble

Question 8

What optical changes are involved in cataract formation?

Answer 8

Structural changes increase light scatter

Question 9

What happens during cataract surgery?

Answer 9

Small incision in limbus 
Phacoemulsification 
Intramural lens insertion 
No sutures 
Day case procedure

Question 10

What are opticians looking for when screening for glaucoma?

Answer 10

Pathological optical disk cupping

Raised intraocular pressure

Question 11

What are the 2 main types of eye drops that can be used to treat glaucoma and how do they work?

Answer 11

• Some decrease aqueous production therefore lowering intraocular pressure.
  Include sympathomimetics - reduce blood flow to ciliary processes, stimulate receptors on deny late cyclise that reduce ion transport. Beta-blockers - block receptors on deny late cyclase that normally increase ion transport. Carbonic anhydrase inhibitors - inhibit production of bicarbonate ions that draw water out

Increase aqueous drainage
Act on sympathetic nervous system to directly increase outflow through the trabecular meshwork via adrenergic receptors or on parasympathetic nerves to contract the ciliary muscles increasing trabecular outflow via muscarinic receptors

Question 12

What are the surgical interventions for glaucoma?

Answer 12

Laser trabeculoplasty
Trabecular meshwork opened with laser

Trabeculectomy
Small part of trabecular meshwork removed

} improves trabecular outflow

Question 13

Which is the commonest cause of blindness across the world? 
A. Refractive error
B. Glaucoma
C. Diabetic retinopathy
D. Cataract 
E. Age related macular degeneration

Answer 13

D

Question 14

Which statement is true?
A Cataract may be described as skin growing under the eye
B. Glaucoma refers to a group of conditions characterised by raised intraocular pressure
C. Smoking is a risk factor for age related macular degeneration
D. Over 75% of patients have some form of diabetic retinopathy after 5 years with diabetes
E. Over 150 million people suffer with visual impairment due to all of the conditions mentioned above

Answer 14

C

Question 15

What are the 4 risk factors for age related macular degeneration

Answer 15

Age = 50+
Smoking
Family history
High blood pressure, cholesterol, fat intake, qBMI

Question 16

What is believed to slow down age related macular degeneration ?

Answer 16

Antioxidants
Zinc
Lute in and zeaxathin supplementation
Dietary modification

Question 17

What are the 2 types of macular degeneration?

Answer 17

Dry - most common but no current treatment

Wet - Abnormal new blood vessels leak or bleed. Can be treated with injections of anti-vascular endothelial growth factor, surgical translocation of the macula

Question 18

After 20 years with diabetes, what percentage will have developed some form of diabetic retinopathy? 
A. 25%
B. 50%
C 75%
D 100%

Answer 18

C