Ex3 L14 Macular Degeneration

Question 1

What is the macula?

Answer 1

• located in the center of the retina
• responsible for central vision
• highest concentration of cones (color vision, but less sensitive to light)

Question 2

Damage to the macula leads to…

Answer 2

macular degeneration, blurred central vision

Question 3

What is the RPE?

Answer 3

retinal pigment epithelium
- controls delivery of oxygen and nutrients to the retina and removes waste

Question 4

How do photoreceptors and the RPE interact?

Answer 4

• photoreceptors depend on the RPE for phagocytosis of the outer segments (source of cellular debris)
• both are subject to chronic irradiation by visible light

Question 5

What lies below the RPE?

Answer 5

Bruch’s membrane
- inner most layer of the choroid
- choriocapillaries are immediately below Bruch’s membrane

Question 6

Describe Age-related Macular Degeneration?

Answer 6

• AMD is the leading cause of blindness in the US for people over 55
• risk factors are age, race, smoking, high cholesterol, and genetics
• causes loss of central vision
• early diagnosis improves prognosis (eye exams recommended after age 60)

Question 7

What are the two types of AMD?

Answer 7

dry (non-neovascular) and wet (neovascular)

Question 8

What is Dry AMD?

Answer 8

• non neovascular
• most common form
• Drusen are deposited under the macula (do not immediately cause visual changes)
• over time can coalesce and cause geographic atrophy (GA) of the retinal pigment epithelium

Question 9

What is Wet AMD?

Answer 9

• neovascular
• involves choiroidal neovascularization (CNV)
• blood vessels grow through the macula after it is weakened by dry AMD, causing bleeding and scar tissue formation
• associated with more rapid and severe vision loss
• less than 10% of AMD is the wet form, but 90% of AMD patients with severe vision loss have wet AMD

Question 10

What are the stages of AMD?

Answer 10

early - small drusen
intermediate - medium/large drusen and geographic atrophy that does not extend into the macula
advanced nonneovascular - many large drusen and geographic atrophy extends into the macula
advanced neovascular - choroidal neovascularization

Question 11

Regarding the pathogenesis of AMD, abnormalities have been observed in:

Answer 11

• photoreceptors
• retinal pigment epithelium (most likely the crucial event)
• Bruch’s membrane
• choriocapillaries

Question 12

Regarding the pathogenesis of AMD, the mechanism is likely…

Answer 12

• oxidative stress resulting from poor diet (too few antioxidants)
• overactivity of immune system, chronic local inflammation, and hypoxia
• altered lipid metabolism

Question 13

How can AMD be prevented?

Answer 13

• proper nutrition
• antioxidants and supplements (AREDS)
• exercise and weight loss
• smoking cessation

Question 14

What is the treatment for dry AMD?

Answer 14

• AREDS2 (antioxidants)
• early diagnosis and management can slow progression
• no current options to reverse disease
• two complement inhibitor drugs approved in 2023 to treat GA
• many drugs are in development/trial

Question 15

What is the treatment for wet AMD?

Answer 15

• laser photocoagulation
• anti-angiogenics (target VEG-F or antiopoietin-2)
  – ex: Susvimo: port delivery system for anti-VEGF drugs, currently recalled
• gene therapy

Question 16

Describe societal views of blindness

Answer 16

• 71% fear blindness more than deafness
• 75% fear blindness more than being wheelchair bound
• 70% fear blindness more than losing a limb
• AMD patients are 2-3x more likely to experience depression