D: Vitreoretinal Interface and Macular Disease - Week 7

Question 1

Describe the pathophysiology of macular oedema

Answer 1

fluid accumulation into the retina due to a breakdown of the blood-retina barrier

Question 2

Where does fluid accumulate in macular oedema? (2)

Answer 2

Can accumulate either intercellularly or intracellularly (primarily within muller cells)

Question 3

Describe the relationship of muller cells with macular oedema in terms of pathogenesis

Answer 3

In macular oedema, Muller cells have impaired potassium transport, which disrupts osmotic water transport through these cells.

This results in:

• Less fluid clearance from retinal tissue
• Muller cell swelling (via osmotic influx from too much potassium in the cell)

Question 4

Does the mechanism of macular oedema differ based on cause?

Answer 4

Yes.

However generally they all tend to involve muller cell dysfunction (e.g. ocular inflammation , diabetes, ischemia, retinal degen)

It’s how they actually get to this muller cell related blood retina barrier breakdown and the end result of fluid accumulation that differs primarily

Question 5

What is the main role of muller cells in the normal eye? (2)

Answer 5

Muller cells are involved in regulating water/ion homeostasis and in maintaining the inner blood retinal barrier

Question 6

List 10 causes of macular oedema (first 4 very important/relevant I think)

Answer 6

Diabetic Retinopathy
Epiretinal membrane (vitreomacular traction)
Retinal detachment (after reattachment)
Branch retinal vein occlusion

Retinitis pigmentosa
Chronic uveitis
Intraocular surgery
Choroidal tumours
Perifoveal telangectasis or Coats Disease
Idiopathic

Question 7

Can macular oedema occur in response to topical medication? If so, which one?

Answer 7

Yes. Latanaprost (xalatan)

Presumably very rare though.