Diabetes Mellitus Flashcards
What are the 3 structural change in Diabetic retinopathy?
- Microvascular circulation changes from prolonged hyperglycaemia (due to compromise of the blood – retinal barrier)
- Microaneurysm
- Changes in haemodynamic
What is the pathogenesis of Diabetic Retinopathy
- Vascular occlusion
• Capillary occlusion: Loss of pericytes, thickening of basement membrane, damage, and proliferation of endothelial cells
• Haematological: deformation and increased platelet aggregation leading to decreased oxygen transport
o Results
1. Retinal ischemia – initially developed in the mid – peripheral retinal. 30% of haemorrhages, microaneurysms (MA), IRMA and NVE occurred outside the 7 ETDRS zones (posterior pole and mid retina). Lesions observed outside the ETDRS zones increased DR severity grading in 10% of patients.
2. Arteriovenous shunts (intraretinal micro – vascular abnormalities) = due to capillary occlusion that run from arterioles to venules
3. Neovascularisation cause by growth factors released from hypoxic tissue in an attempt to revascularize hypoxic retina. Promotes neovascularisation of retina, optic nerve, iris (rubeosis iridis) - Vascular leakage
• Pathogenesis = breakdown of inner blood-retinal barrier leads to leakage of plasma constituents into the retina
• Leads to increased vascular permeability –development of intraretinal haemorrhages and oedema
• 2 general types of retina oedema
o Diffuse retinal oedema = due to capillary dilatation and leakage
o Focal retinal oedema = Chronic retinal oedema leads to deposition of hard exudates
• Hard exudates = occur at the border of normal and oedematous retina composed of lipoprotein and lipid-filled macrophages
What is HbA1c?
a measure of how much haemoglobin in the blood which is an index of long-term blood glucose control.
What are the risk factors for diabetic retinopathy?
Duration of Diabetes
Elevated HbA1c
Px with systemic hypertension
Px with hyperlipidaemia (high chlorestorol)
Pregnancy
Neuropathy
Gender - male
smoking status, ethnicity and type 1 DM
What are the systems of diabetic retinopathy?
Fluctuating vision, vision blurriness that cant be corrected with refraction, sudden eye pain and redness
acute onset flashes and/floaters
What are these symptoms indicative off:
Fluctuating vision, vision blurriness that cant be corrected with refraction, sudden eye pain and redness
acute onset flashes and/floaters
Diabetic retinopathy
What are the Anti VEGF treatments for Diabetic Macular Oedema?
1.Ranibizumab= binds and inhibits all identified VEGF isoforms
2.Bevacizumab = recombinant, humanized, antibody that binds to and inhibits the biologic activity of all isoforms of human VEGF. Originally approved by the FDA for use in patients with metastatic colorectal cancer.
3.Aflibercept= exhibits higher affinity for VEGF-A/-B and binds all the VEGF isoforms
What are the three Ophthalmology management for Clinically significant Macular Oedema?
Ophthalmology Management
1. Laser Photocoagulation
• Focal laser treatment applying laser burns (permanent structural damage to areas with MA or microvascular lesions. Treatment of lesions up to 300 µm from foveal centre
• Grid laser treatment used for areas of diffuse retinal thickening more than 500 µm
• Results: 70% achieve stable VA, 15% show improvement
2. Panretinal laser photocoagulation (PRP)
• Purpose: to induce involution of new vessels and prevent vision loss from vitreous haemorrhage (VH) and retinal detachment
• Treatment: 2000-3000 laser burns covering the peripheral retina in several session depending on pain threshold of patients.
3. Pars Plana Vitrectomy
• excision of posterior hyaloid face, relieving the vitreous/retinal traction and reattaching the retina and creating a vitreous cavity for filling with gas/silicone or internal tamponade
• Indication: Proliferative DR with VH or tractional Retinal detachment
What is the purpose of CSME ophthalmologic treatment?
Purpose:
• 1.Removal of vitreous gel: removes the stimulus for further fibrovascular tissue can proliferate
• 2.Removal of vitreous haemorrhage
• 3.Repair retinal detachment
• 4.Prevention of further neovascularization by applying laser photocoagulation
What are some complications that can arise from CSME surgery?
Complications
• 1.Rubeosis iridis
• 2.Cataract
• 3.Glaucoma secondary to rubeosis iridis
• 4.Recurrent VH
• 5.Retinal detachment
What is required for a diagnosis of Clinically Significant Macular Oedema?
One or more of the following
- Thickening of the retina ≤ 500 microns (1/3 DD) from the centre of the macula
- Hard exudates ≤ 500 microns (1/3 DD) from the centre of the macula with thickening of the adjacent retina
- Area of retina thickening ≥ 1 DA in size, any portion which ≤1 DD from the centre of the macula
- Microaneurysms, haemorrhages, IRMA and venous beading
- Non-Centre Involving (Mild) Macular Oedema
- Centre Involving (Severe) Macular Oedema
- Centre Approaching (Moderate) Macular Oedema
- Diabetic Maculopathy
What is required for a diagnosis of Diabetic Maculopathy>
Diabetic Maculopathy – macular oedema on/off centre with clinical features of ischemia
- Hard exudates
- Retinal oedema
- Cystoid retinal changes
- Dark haemorrhages
What are the features of Mild NPR - no macular oedema?
Frequency of follow up?
Management plan?
Appropriate referral?
Microaneursyms only
12 months
Communication with GP
no referral required
What are the features of Mild NPR - macular oedema?
Frequency of follow up?
Management plan?
Appropriate referral?
Microaneursyms only
4 - 6 months
Photo documentation
retinal ophthalmology review in 4 - 6 weeks
What are the features of Mild NPR - CSME?
Frequency of follow up?
Management plan?
Appropriate referral?
Microaneursyms only
2 - 4 months
Photo documentation including GA or OCT - A
retinal ophthalmology review in 2 - 4 weeks
What are the features of Moderate NPR - No macular oedema?
Frequency of follow up?
Management plan?
Appropriate referral?
Any of the following
-retinal dot and blot haemorrhages
-hard exudates or cotton wool spots
- +/- microaneurysms
- no signs of severe non-proliferative diabetic retinopathy
6 - 8 months
Communicate with GP + Photo documentation
No referral required
