5. Diabetic Retinopathy and AMD Flashcards
What percentage of the diabetic population has Diabetic Retinopathy?
40.00%
In which type of diabetes is DR more common?
Type 1
What percentage of the diabetic population has sight threatening disease?
10.00%
What percentage of the diabetic population has Proliferative Diabetic Retinopathy?
10.00%
What are the risk factor for the development of DR?
Duration of Diabetes Poor Control of Blood Glucose Levels Pregnancy Hypertension Nephropathy Other (Anaemia, hyperlipidaemia, smoking)
Describe the pathogenesis of DR.
- Cellular damage (due to sorbitol accumulation & oxidative stress)
- Capillaropathy (death of pericytes, thickening of capillary basement membrane & endothelial cell proliferation = Leakage of fluid+Microaneurysm
- Haematological changes as increased platelet stickiness = Capillary occlusion+ Ischaemia
What is the difference between proliferative and non-proliferative DR?
Neovascularization in Proliferative DR
What causes neovascularisation in DR?
Capillary non-perfusion = retinal hypoxia = stimulate angiogenesis = neovascularization (PDR Proliferative Diabetic retinopathy)
There are many angiogenic stimulators: Vascular Endothelial Growth Factor VEGF
Outline how DR is classified?
Background Diabtetic Retinopathy (BDR)
Diabetic Maculopathy
Proliferative Diabetic Retinopathy
Advanced Diabetic Eye Disease
What are the characteristics of Background DR
Microaneurysms
Blot & dot haemorrhages
Exodates (Hard Exudate (Flame - lipoprotein), Soft Exudate (Spots – ischemia)
What is Diabetic Maculopathy?
Oedomatous and ischaemic damage of the macula which threatens vision
Describe the different types of Proliferative Diabetic Retinopathy?
Neovascularization at the disc (NVD) Neovascularization elsewhere (NVE)
What constitutes advanced diabetic eye disease?
Retinal Detachment
Vitreous haemorrhage
Neovascular Glaucoma
Describe the optical coherence tomography?
Non-invasive, non-contact imaging system
Provides high resolution cross sectional imaging of the retina
Analogous to B-scan (light hits area of different refractive index it bounces back) ultrasonography but uses near-infrared light rather than sound waves
What is the OCT principle?
The various layers,they’re thickness and they’re relative density are represented in a cross sectional image.
Describe Fundus Fluorescein Angiography (FFA)
Fluorecein is an orange water-soluble dye
When injected IV, remains mainly intravascular
Disruption of the inner blood retinal barrier will permit leakage of fluorescein
S/E: Anaphylactic (she said epilieptic shock have epi on hand)
Which type of DR does not require treatment? What does it require though?
Background Diabetic Retinopathy does not require treatment, observation only
What is the Tx for Macular Oedema?
Intravitreal anti-VEGF agents (usually has to be repeated as effects wear off)
Laser photocoagulation to leaking areas in FFA
Not always successful (70% will have stable vision, 15% better, 15% worse)
See floaters
Risk of Infection
Risk of Uvitits
2/3 sessions 4-6 weeks apart
4 weeks later repeat OCT
Use fluorescence to find leaks
What is the Tx for proliferative diabetic retinopathy?
Laser/ Panretinal photocoagulation PRP
If we burn out these area stop advance
Describe Laser photocoagulation use in PDR?
Aim is to induce the involution of new vessels, thereby preventing visual loss
It photocoagulate/burns the retinal tissue
This would reduce the overall oxygen demand of the retina
Less stimulation for neovascularization
Laser is a permanent treatment
May reduce peripheral vision
What is the Tx for Vitreous Haemorrhage?
Vitreous haemorrhage: wait 6 months to clear by itself, then do vitrectomy if still not absorbed
Vitrectomy
Opening up to remove the vitreus and insert fluid which would be replaced eventually with fluid from the body.
Also trying to resolve/limit any retinal detachment by removing fibrous tissue
Worst Outcomes
May loose peripheral vision
Wont be able to drive (minimum 120 degree vision)
Laser may reduce peripheral vision
What is ARMD?
Is a degenerative disorder affecting the macula
What are the symptoms of ARMD?
Loss of central vision
Metamorphopsia
Early clinical findings including drusen & RPE changes
Will be hyper and hypo pigmentation
Patient 40/50yo losses central vision since disease affects the macula
Will see wavy lines since there are waves formed inside the retina
What are the risk factors for ARMD
Age
Race, more common in Caucasians
Heredity
Smoking
Hypertension
Dietary factors, high fat intake & obesity may promote AMD.
Antioxidant intake have protective effect
