Opth Diabetic Retinopathy Flashcards
changes with aging
Accomodation: can’t see as well with close up material, reading, muscles can’t contract as well
Glare: increased sensitivity, glossy materials
Attentional visual field: gets smaller, cognitive process
Dark adaptation: takes longer to adapt, can take more than 1 min (hazard such as when driving)
Colour discrimination: pastels look similar
Diabetic Retinopathy (DR)
Retinopathy is any damage to the retina, the part inside the eye that senses light.
• Microvascular Complications of diabetes
• Characterized by slow and progressive damage to the retinal microvasculature, retinal
neurons and glial cells
Epidemiology
- Most common cause of new-onset blindness in the working-age population
- 34.6% worldwide prevalence of DR in adults with diabetes
- Affecting ~ 500,000 Canadians
- T1DM: Rarely develops if < 10yo, sharp increase after 5y in post-pubertal patients
- T2DM: Retinopathy present in 21-39% of patients soon after diabetes diagnosis
- Sight-threatening in ~3%
- Early detection and treatment= 95% reduced risk of blindness!
Anatomy
• The retina is a thin layer of lightsensitive nerve tissue that lines the back of the eye (or vitreous) cavity, • Two vasculatures provide the retina with a constant supply of O2 and nutrients to meet the high metabolic demands
Pathogenesis
• Complex interplay of multiple mechanisms
• Chronic hyperglycemia and associated altered
metabolic pathways can lead to:
• Neurodegeneration - thinning retinal
ganglion cell and nerve fiber layers
• Vascular damage -↑VEGF, inflammatory
mediators production, RAAS activation
• e.g. Retinal hemorrhages, vascular
leakage, retinal capillary nonperfusion,
edema
• Impaired neurovascular unit function
• As DR progresses, retinal vessels close
resulting in reduced perfusion and retinal
ischemia
Classification
• Clinically defined as 2 stages:
1. Non-proliferative (NPDR) -Early stage
• Progressive, patients may be asymptomatic
• Microaneurysms, hemorrhages, hard exudates, macular edema
2. Proliferative (PDR) –Advanced stage
• Characterized by neovascularization of the disk, retina, or iris
• Patients may experience severe vision impairment
• Vitreous hemorrhage, fibrosis, traction retinal detachment, macular edema
Forms of Retinopathy
• 3 forms based on the extent of retinal vascular disease detected by ophthalmoscopy:
1) Macular Edema
▪ Diffuse or focal vascular leakage at the macula
▪ Most common cause of vision loss, can occur at any stage
2) Progressive accumulation of microvascular change
▪ Non-proliferative/Proliferative Retinopathy
3) Retinal capillary nonperfusion
▪ Form of vascular closure detected on retinal angiography, can cause blindness
Risk factors
• Longer duration of diabetes • DR develops in 50-90% of patients with DM for ≥20 years • Hyperglycemia (Elevated A1C) • Hypertension • Proteinuria • Dyslipidemia • Pregnancy (T1DM) • Severe retinopathy itself • Other: obesity, anemia, inflammatory markers, Hispanic and South Asian ethnicity, and some genetic markers, cataract surgery
Screening
• Why?
• Asymptomatic presentation is possible, rate of progression may be rapid, therapy
beneficial for both symptom amelioration and reduction in the rate of disease
progression ↓ risk of blindness
• When to initiate screening:
• Type 1 diabetes: 5 years after diagnosis in all individuals ≥15 years
• Type 2 diabetes: children, adolescents and adults at diagnosis
• If retinopathy present: yearly or more often depending on DR severity
• If retinopathy not present
• T1DM: rescreen annually
• T2DM: rescreen every 1 to 2 years
Screening Methods
- Gold standard: 7-standard field, stereoscopic-colour
fundus photography with interpretation by a trained
reader - Direct ophthalmoscopy or indirect slit-lamp
fundoscopy through dilated pupil - Digital fundus photography
• Evaluation should be performed by an experienced
vision care professional (optometrist or
ophthalmologist)
Symptoms
Most patients are asymptomatic until advanced stages of disease • Symptoms may occur in one or both eyes, includes: • blurred vision • narrowed field of vision • seeing dark spots • feeling of pressure or pain in eyes • difficulty seeing in dim light
Impact
• Significant morbidity: including increased falls, hip
fracture, depression
• 4-fold increase in premature death
• Early death (in type 1 diabetes)
Goals:
• Prevent onset of retinopathy by optimizing metabolic and blood pressure control (primary prevention) • Delay progression of retinopathy • Preserve and improve vision • Promote independence and QOL
Diabetes
Management
ABCDESSS
Delay of
Onset and
Progression
- Glycemic control
- BP control
- Lipid-lowering therapy
