6.1.10 Recognises, evaluates and manages diabetic eye disease and refers accordingly.

Question 1

Type 1 Vs Type 2

Answer 1

Type 1 vs. Type 2 Diabetes Overview

Type 1 Diabetes
- Nature: Autoimmune disease.
- Cause: Immune system attacks insulin-producing beta cells in the pancreas.
- Progression:
- Beta cells are gradually destroyed.
- Pancreas eventually stops producing insulin entirely.
- Unknown Factors:
- Exact cause and preventive measures remain unclear.

Type 2 Diabetes
- Nature: Metabolic disorder.
- Cause:
- Body develops insulin resistance (cells no longer respond effectively to insulin).
- Pancreas compensates by producing more insulin, but this becomes unsustainable over time.
- Progression:
- Excess strain on beta cells leads to their dysfunction and eventual destruction, reducing insulin production.

Key difference: Type 1 involves complete insulin deficiency due to autoimmune destruction, whereas Type 2 stems from insulin resistance and eventual beta cell failure.

Question 2

Pathogenesis of Diabetic Retinopathy

Answer 2

• Microangiopathy
- A condition affecting small blood vessels (capillaries).
- Cause: High glucose levels damage capillaries, leading to:
1. Microvascular leakage.
2. Microvascular occlusion.

• Microvascular Occlusion
- Capillary Changes:
- Damage to the basement membrane and endothelial walls.
- Reduced red blood cell deformability (RBCs become less flexible).
- Platelets become stickier, promoting blockages.

• Outcomes:
  
  • Capillaries become easily blocked, leading to areas of retinal ischemia.
  • Ischemia stimulates production of VEGF (vascular endothelial growth factor) and IGF-1 to promote new vessel growth.
• New Vessels:
  
  • Fragile and prone to leakage.
  • Poor structural integrity due to being anchored on unstable vitreous scaffolding.
• IRMA (Intraretinal Microvascular Abnormalities):
  
  • Develop at the edge of occluded areas as a response to ischemia.

Microvascular Leakage
- Loss of Pericytes:
- Pericytes provide structural support to capillary walls.
- Damage to pericytes weakens capillaries.

• Consequences:
  
  • Formation of microaneurysms (outpouching of weakened capillary walls).
  • Leakage of fluid or blood leads to:
    
    • Intraretinal hemorrhages.
    • Retinal edema.

Question 3

Anatomy of Retinal Findings in Diabetic Eye Disease

Answer 3

• Exudates:
  
  • Typically accumulate around the Inner Plexiform Layer (IPL) and Inner Nuclear Layer (INL).
  • Appear as dense shadows with minimal visibility.
• Flame-Shaped Hemorrhages:
  
  • Located in the Retinal Nerve Fiber Layer (RNFL) near the retinal surface.
  • Their shape reflects the alignment of nerve fibers in this layer.
• Dot-Blot Hemorrhages:
  
  • Found deeper, between the Inner Plexiform Layer (IPL) and Outer Plexiform Layer (OPL).
  • Small, rounded shape due to their location within compact retinal layers.
• Exudates:
  
  • Concentrated in areas surrounding the IPL and INL.
• Oedema:
  
  • Localized between the Outer Plexiform Layer (OPL) and Inner Nuclear Layer (INL).

Question 4

Types of DR

Answer 4

 Background diabetic retinopathy: microaneurysms, dot/blot haemorrhages and exudates more than 2DD from fovea

 Pre-proliferative diabetic retinopathy: cotton wool spots, venous beading, IRMA, deep retinal haemorrhages, exudates within 2DD of fovea

 Proliferative diabetic retinopathy: loss of vision/reduced VA (pre-retinal haemorrhage), exudates within 1DD of fovea, retinal neovascularisation on/within disc diameter and/or new vessels elsewhere

 Advanced diabetic eye disease is characterised by tractional retinal detachment, significant persistent vitreous haemorrhage and neovascular glaucoma.

 Diabetic maculopathy: refers to presence of any retinopathy at the macula

Question 5

Grading of DR/DRM

Answer 5

R0 – no retinopathy

R1 – mild background retinopathy
 At least one of the following features anywhere: dot haemorrhage, cotton wool spot, blot haemorrhage, flame shaped haemorrhage
 Rescreen in 12 months for DRS

R2 – moderate background
 4 or more haemorrhages in one hemi-field only
 Rescreen in 6 months

R3 – severe background / pre-proliferative
 4 or more haems
 Venous beading / IRMA

R4 – proliferative
 Active new vessels
 Pre-retinal haemorrhage
 Retinal neovasc NVD, NVE

M0 – no maculopathy

M1 – early
 Exudates >1 but <2DD from fovea

M2 – advanced
 Haemorrhages or exudates within 1DD from fovea

Question 6

Referral

Answer 6

 No referral - Background retinopathy (R1 – R2)
- Microaneurysms, dot/blot haemorrhages
- Exudates >2DD from fovea

 Routine - Pre-proliferative – exudates within 2DD of macula (R3 / M1)
- Cotton wool spots, venous beading, IRMA, deep retinal haemorrhages
- Exudates < 2DD of macula

 Urgent - Proliferative DR and maculopathy (R4 / M2)
- Retinal neovascularising within disc diameter and/or new vessels elsewhere
- Pre-retinal fibrosis
- Exudates <1DD from fovea

 Emergency referral
- Pre-retinal haemorrhage
- Traction retinal detachment
- Rubeosis

Question 7

Diabetic maculopathy

Answer 7

 Maculopathy = features of retinopathy which lie specifically within macular area

 Macula specific diabetic pathology that will cause sight loss:
o Macular oedema
o Macular ischaemia – unable to treat (won’t occur without lots of other retinal features of ischaemia)

• Do not need to refer 1 small-isolated dot haem within 1DD of fovea
• SHOULD refer exudate within 1DD of fovea
• SHOULD refer retinal thickening within 1DD

Question 8

Other Diabetic ocular affects

Answer 8

Ocular Complications in Diabetes

Corneal Neuropathy
- Pathophysiology: Reduction in corneal nerve density leads to corneal desensitization.
- Progression:
- Initially presents as dry eye disease (DED) symptoms.
- Progresses to:
- Breakdown of corneal epithelium.
- Corneal edema.
- Corneal ulcers.

Delayed Healing of Corneal Epithelium
- Risks:
- Increased susceptibility to infections.
- Persistent epithelial defects.

Cataracts
- Age-Related Cataracts:
- Nuclear sclerosis (NS), cortical opacities (CO), and posterior subcapsular cataracts (PSC).
- Occur earlier and may progress faster in diabetics.
- Diabetic Cataracts:
- Seen in young diabetics.
- Characterized by snowflake opacities.

Ocular Muscle Involvement
- 3rd Nerve Palsy:
- Ischemic etiology usually spares the pupil due to microvascular damage.
- Other Cranial Nerves:
- 6th nerve palsy is the most common.
- Can also affect the 4th nerve.

Question 9

Advice management

Answer 9

 Good management significantly reduces risk profile
 Smoking cessation
 Managing weight
 Managing diet

Question 10

Medications

Answer 10

Diabetes Medications and Their Ocular Effects

Insulin
- Side Effects:
- May cause hypoglycemia, leading to dizzy spells.
- Rarely, initial treatment may cause transient presbyopia due to fluid shifts affecting the lens. This typically stabilizes.

• Types:
  
  • Novorapid:
    
    • Active Ingredient: Insulin Aspart.
    • Fast-acting, works within 10–20 minutes.
    • Duration: 3–5 hours.
  • Levemir:
    
    • Active Ingredient: Insulin Detemir.
    • Long-acting, administered via subcutaneous injection.
    • Duration: Up to 24 hours.

Metformin (Biguanide)
- Used for Type 2 Diabetes (T2DM).
- Side Effects:
- Can contribute to dry eye.
- May increase the risk of angle-closure glaucoma in predisposed individuals.

Gliclazide
- Commonly prescribed for T2DM.
- Side Effects:
- Associated with lens changes.
- May cause refractive error shifts, potentially requiring changes to prescription glasses.

Question 11

Management of difference diabetic retionapthies/maculopathies

Answer 11

Management of Diabetic Retinopathy

Background & Pre-Proliferative Stages
- Background Retinopathy:
- Typically requires monitoring only.
- Pre-Proliferative Retinopathy:
- Management depends on severity of retinal bleeds and risk of progression.

Proliferative Diabetic Retinopathy (PDR)
- Panretinal Photocoagulation (PRP):
- 2,000–4,000 laser burns applied to the peripheral retina.
- Goals:
- Reduce VEGF drive.
- Destroy ischemic retina to reduce oxygen demand.
- Preserve central vision by sacrificing peripheral retina.

Advanced Proliferative Diabetic Retinopathy
- Multiple PRP sessions may be required.
- Vitrectomy:
- Used to manage complications like vitreous hemorrhage, retinal detachment, or tractional changes.
- Rubeotic Glaucoma:
- Often requires additional interventions to manage.

Diabetic Macular Edema (DME)
- Anti-VEGF Therapy:
- Agents like Ranibizumab (Lucentis®) administered intravitreally.
- Benefits:
- Arrests or reverses macular edema and proliferative changes.
- Less destructive than PRP.
- Intravitreal Corticosteroids:
- Used for cases unresponsive to anti-VEGF.
- Results:
- Modest improvement in visual acuity (VA).
- Long-acting steroid implants may be considered for sustained treatment.

Question 12

Cotton Wool Spots

Answer 12

Isolated cotton wool spots (one or more) in the absence of any microaneurysm or haemorrhage should be counted as no DR (R0).

Any number of cotton wool spots (CWS) in the presence of other non‐referable features of DR should be graded as background DR (R1).