Retina 1 - Vitreoretinal interface

Question 1

What is the vitreous?

Answer 1

•Transparent gel filling space between retina and lens
•Integrated with retina and para plana at vit base, loosly adherent at disc
•Lattice like structure
•99% water
- Also contains hyaluronic acid
- Type 2 and 9 collagen
- Aminoglycans
- Few cells

Question 2

What is the vitreous for?

Answer 2

•Can be removed in adults with no damaging consequences
•In children however its needed for growth of eye - emmetropisation

Question 3

How does the vitreous age?

Answer 3

•Type 9 - “Bolts”
•Type 2- “Metal polls”
- By 22, 75% of collagen type 9 is lost
•Called vitreous liquefaction
- Specifically called vitreous syneresis
•Eventually breaks into the posterior hyaloid space
- Posterior vitreous detachment (PVD)

Question 4

Symptoms of vitreous ageing?

Answer 4

•Floaters
- Described as “Cobwebs”
•Flashes
- Single flashes
- Not like fortification spectra
•None
- Many are asymptomatic

Question 5

Signs of PVD?

Answer 5

•Weiss ring
- Glial tissue from around the disc
- Usually not an obvious ring
- Best seen with: Bright light, slightly oblique, in front of and below disc
•Posterior hyaloid
- Crinkly grey membrane behind lens

Question 6

Epidemiology of PVD and it’s risk factors?

Answer 6

•Prevalence
- Approx 25% over 60
- Approx 50% over 70
•Risk factors
- Age
- Myopia
- Cataract surgery
- Ethnicity not shown to be relevant

Question 7

Why does PVD matter?

Answer 7

•Good news
- Minimal risk of macular hole
- Minimal risk of proliferative diabetic retinopathy
•Bad news
- Risk of retinal break and detachment
- 8-12% risk of break in symptomatic PVD

Question 8

How does PVD cause a tear?

Answer 8

•Due to firm adherence of vitreous to retina at base
•Increase risk of retinal tear with lattice degeneration
• Mechanical traction at vitreous base ISN’T evenly distributed, resulting in a horseshoe tear

Question 9

what techniques can be used to detect a retinal tear?

Answer 9

•Fully dilate patient
•Non contact with 90D or super field lens
•360 indentation with binocular indirect
•3-mirror goldmann lens
- May get hazy due to corneal haze
•Scleral Indentation
•Shafers sign
- RPE cells exposed in vitreous due to tear in retina.
- 92% chance tear if shafers sign shown

Question 10

Treatment of PVD

Answer 10

•Patients will initially very symptomatic
•Most will find that symptoms get much less over a few months
•A few will remain symptomatic
•Options include:
- Vitrectomy
- Vitreolysis

Question 11

Treatment of horseshoe tear

Answer 11

•Treated urgently
• Usually laser
• May use Cryotherapy
• Retinal detachment remains a risk for one week
•Does not affect symptoms

Question 12

Lattice degeneration and it’s relation to RD statistics?

Answer 12

•Prevalence
- Normal eyes: 6-8%
- RD eyes: 30%
•Risk of RD from lattice
- 276 patients followed for 1-25years
- 3 clinical RD developed in 0.7% of eyes and 1.1% of patients
•Routine prophylaxis is not justified

Question 13

Round hole related to retinal detachment?

Answer 13

•Prevalence
- Normal eyes 6%
•Risk of RD with round hole?
- 235 eyes in 196 patients followed for 1-33 years (avg 1- years)
- One clinical RD developed
- 19 eyes had sub-clinical detachment
•Routine prophylaxis is not justified

Question 14

Prophylaxis in relation to lattice degen or flat round holes?

Answer 14

•Prophylatic treatment of lattice or flat round holes is not justified
•No need to refer patients with lattice or round hole
- As wont be treated