16 DIABETES: Flashcards
Three structural changes in diabetic retinopathy
Microvascular circulation changes from prolonged hyperglycemia (compromise blood-retinal barrier) (e.g. venous dilation, increased retinal blood flow, tissue hypoxia, loss of pericites in retinal capillaries, thickening of basement membrane, damage and proliferation of endothelial cells → capillary non-perfusion and loss)
Microaneurysms (Etiology: mechanical weakness of capillary wall, vasoproliferation of endothelium), (Pathogenesis: breakdown of inner BRB, microaneurysms develop as physical weakening of capillary walls → localized saccular outpouchings of vessel walls)
Changes in haemodynamics (microvascular abnormality formation produces leakage of plasma, haemorrhage and vascular shunting)
Diabetic Retinopathy PATHOGENESIS and RESULTS
Vascular occlusion (Capillary occlusion: loss of pericytes, thickening of basement membrane, damage and proliferation of endothelial cells) (Haematological: decreased oxygen transport) → RESULTS in retinal ischaemia, arteriovenous shunts, neovascularization of retina, optic nerve, iris (rubeosis iridis)
Vascular leakage (breakdown of inner BRB leads to leakage of plasma constituents into the retina) → RESULTS in increased vascular permeability (development of intraretinal haemorrhages and oedema). [two types of retinal oedema: diffuse = due to capillary dilation and leakage, focal = chronic retinal oedema leads to deposition of hard exudates]
What is HbA1c
Glycated haemoglobin
Haemoglobin is a component of RBC and binds to oxygen and glucose (becoming ‘glycated’)
HbA1c measured as an index for long term blood glucose control
Risk factors of Diabetic retinopathy
Duration of diabetes (>10yrs = 50% present, >30yrs = 90% present)
Elevated HBA1C (>8% significant risk)
Hyperglycaemia (fasting glucose > 7.03mmol/L)
Systemic hypertension
Hyperlipidemia (obesity)
Pregnancy (rapid progression of retinopathy)
Nephropathy (renal disease)
Gender (male)
Smoking status, ethnicity, dependence on insulin
Symptoms
Fluctuating vision - related to fluctuating blood glucose
Symptoms more suggestive of urgent referral: vision blurriness not correctable with refraction, sudden eye pain/redness, acute onset flashes and/or floaters
Signs and symptoms LIDS and CONJUNCTIVA
Signs: infection, inflammation, ulcerative blepharitis, styes, chalazion, conjunctivitis
Symptoms: sticky lids in the morning, sting or burning, redness or irritation, tearing, mucus or pus, visible or sensation of lumps, punctate epithelial erosions (PEE), SPK, reduced TBUT
Signs and clues CORNEA
Signs: corneal keratopathy, decreased corneal sensitivity/nerve density, corneal ulcers, corneal edema, altered epithelium basement membrane
Clues: cotton bud test, CL related infections/inflammations, stinging/burning, prolonged eye irritations, dry eyes, no discomfort on instilling dilation eye drops, no symptoms with associated ocular finding
Signs and Clues LENS
Signs: fluctuating myopia,, cataracts, light sensitivity
Clues: vision & prescription changing, glare/haloes, sensitivity to light, blurred vision that doesn’t improve with lenses/PH, lens opacity/snowflake
Signs and Clues EXTRAOCULAR MUSCLES
Signs: cranial nerve palsy, 3rd nerve (affect eye lid closed/smaller aperture; eye movement cannot move adduct and upwards; pupil can be enlarged and abnormal light reactivity), 4th nerve (vertical diplopia, head tilt, ipsilateral hypertropia), 6th nerve (double vision, affected eye cannot abduct)
Clues: double vision, head tilt, closed eye/smaller aperture, vertical diplopia, shadow/overlap of images, restricted eye movements, any diagnosed diabetic neuropathy
Signs and Clues PUPIL and IRIS
Signs: autonomic neuropathy, rubeosis iridis, neovascular glaucoma
Clues: pupil does not dilate as expected/sluggish, reddish discolouration of the iris, increased eye pressure, blood vessels in angle
Signs and Clues OPTIC NERVE
Signs: optic neuritis, diabetic papillopathy
Clues: slow progressive vision loss, washed out colours, decreased contrast sensitivity, pain and around eyes especially on eye movements and ONH swelling
Visual functional changes and management
Dry eye syndrome (rx of artificial tears, lubricants and dry eye management. Monitor for corneal complications)
Corneal changes (monitor for keratitis, ulceration, delayed wound healing if CL wearer)
Rubeosis iridis (gonio rule out AC involvement and neovas. Tono rule out secondary glaucoma)
Cataracts (monitor lens opacification and status of associated retinopathy; extraction necessary if visualization of retina becomes inadequate)
Colour vision (tritan CV loss - DFE to screen for CSME)
Refractive Error and Acc Dysfunction (consult with GP regarding glucose control and update spx)
EOM palsies (neuro-ophthalmology consultation, prism rx, eye patching)
Afferent Pupillary defects (workup to rule out optic neuropathy)
Classification of Diabetic Retinopathy STAGE 1
Classification of Diabetic Retinopathy STAGE 2
Management of DR STAGE 1
Management of DR STAGE 2
NO abnormalities
Mild non-proliferative diabetic retinopathy. Microaneurysms only
Review 2 yrs. If high risk, review yearly
Review 6-12 months
Classification + Management of Diabetic Retinopathy STAGE 3
Moderate non-proliferative diabetic retinopathy
Retinal dot and blot haemorrhages, hard exudates or cotton wool spots, ± microaneurysms, no signs of severe non-poliferative diabetic retinopathy ANY OF THEM
Management: Review 3-6 months, communicate DR to GP + endocrinologist and mention possible benefits of fenofibrate in slowing DR progression
Classification + Management of Diabetic Retinopathy STAGE 4
Severe non-proliferative diabetic retinopathy
More than 20 intraretinal haemorrhages in each of the 4 quadrants, definite venous beading in 2 or more quadrants, prominent intra-retinal microvascular abnormality (IRMA) in 1 or more quadrants, no signs of proliferative retinopathy ANY OF THEM
Management: Ophthalmology referral
Classification + Management of Diabetic Retinopathy STAGE 5
Proliferative diabetic retinopathy
Neovascularization, vitreous/pre-retinal haemorrhage ONE OR BOTH
Management: Urgent ophthalmology referral (days - weeks)
Proliferative Diabetic Retinopathy NEOVASCULARIZATION and VITREOUS HAEMORRHAGES
Neovascularization of Disc (NVD): new vessel proliferation within one disc diameter from ONH. Mild NVD = <⅓ disc area, severe NVD = >⅓ disc area
Neovascularization elsewhere (NVE): vessel formation frequently arising from veins located elsewhere in the retina. Mild NVE <½ disc area, severe NVE >½ disc area
Vitreous haemorrhages: retinal detachments
What is retinal oedema
Thickening of retina may be localised or diffuse and centre involving or diffuse. Due to leakage of MA, retinal vasculature or choroidal vasculature
What is Clinically Significant Macular Oedema (CSME)
Thickening of the retina ≤ 500 microns (⅓ DD) from the centre of the macula
Hard exudates ≤ 500 microns (⅓ DD) from the centre of the macular with thickening of the adjacent retina
Area of retinal thickening ≥ 1 DA in size, any portion which is ≤ 1 DD from the centre of the macula.
ONE OR MORE
Classification + Management of Diabetic Maculopathy
Absent
No retinal thickening or hard exudates in posterior pole
Management: follow-up or need to refer based on level of NPDR or DR
Classification + Management of Diabetic Maculopathy
Macular oedema stage MILD
Macular oedema stage MODERATE
Macular oedema stage SEVERE
Diabetic Maculopathy
Non centre involving: some retinal thickening or hard exudates in posterior pole but distant from the macula.
Centre approaching: retinal thickening or hard exudates approaching the centre of the macula but not involving the centre
Centre involving: retinal thickening or hard exudates involving centre of the macula
Diabetic maculopathy: macular oedema on/off centre with clinical features of ischaemia (e.g. hard exudates, retinal oedema, cystoid retinal changes, dark haemmorhages)
Management: ophthalmology referral and management (within 4 weeks for hard exudates within 1DD of fovea)
Optometric DR Management (4)
DR screening according to NHMRC guidelines
Referral for management of BP, lipids and glycemic control
Diet and exercise (prevents up to 50% of T2D complications). Diet (475 calorie reduction, less than 80g/day carbohydrates, fish oils in doses of 5g/day, monounsaturated fats), physical activities (aerobic training that makes you ‘puff’ minimum 30 mins 3-4 times/week, >150mins of walking)
Good glycemic contro prevents or delays incidence of retinopathy, neuropathy and nephropathy
Optometric DR Management Targets (5)
HbA1c less than 7%
Systolic BP less than 130mmHg
Normalising blood lipid levels
Renal function: presence of microalbuminuria or over proteinuria (30-300mg/24hrs)
Presence of peripheral neuropathy (tingling numbness in extremities)
