Systemic eye disease Flashcards
What is thyroid eye disease
Autoimmune disease caused by activation of orbital fibroblasts by autoantibodies directed against thyroid receptors
Thyroid eye disease is mostly associated with
Grave’s
90% of thyroid eye disease is associated with Grave’s. How about the rest of the 10%
Normal functioning thyroid
Hashimoto’s
What are the effects on the eye due to TSH receptor autoantibodies in thyroid eye disease
Extraocular muscle enlargement
Orbital fat expansion
Describe the stages of thyroid eye disease
- Soft tissue involvement
- Lid retraction
- Proptosis
- Optic neuropathy
- Restrictive myopathy
Risk factors for development of thyroid eye disease
Smoking
Radioiodine treatment - increases the inflammatory symptoms in thyroid eye disease
Symptoms of thyroid eye disease
Periorbital swelling
Exophthalmos (proptosis)
Unable to close eyelids -> dry eyes, exposure keratopathy
Ophthalmoplegia (weakness of eye muscles) -> double / blurred vision
Unable to close eyelids can lead to
Dry, sore eyes
Exposure keratitis
What ophthalmological feature does dermatomyositis cause
Heliotrope rash on eyelids
Dermatomyositis is a ______ phenomenon hence ______ after diagnosis
Dermatomyositis is a paraneoplastic phenomenon (i.e. it is associated with malignancies - breast, lungs, ovarian) hence patients need to undergo CT chest, abdomen and pelvis after diagnosis
What ophthalmological conditions can Marfan syndrome cause
Dislocated lens
Blue sclera
Myopia
Which type of dislocated lens does Marfan syndrome cause
Superotemporal dislocation
What are the types of diabetic retinopathy
Non-proliferative
Proliferative
Macular edema
Pathophysiology of diabetic retinopathy
- Hyperglycaemia causes increased retinal blood flow and abnormal metabolism of glucose in retinal vessel walls
- This causes damage to endothelial cells and pericytes
- endothelial dysfunction -> increased permeability -> lipids, proteins leak out -> exudates
- Necrosis of the vessel wall triggers release of vascular endothelial growth factor
- this causes formation of new, fragile vessels which can rupture and cause visual loss
What is non-proliferative retinopathy
Early stage of diabetic retinopathy where blood vessels are weakened but have not yet formed new blood vessels
What is proliferative retinopathy
Late stage of diabetic retinopathy where new fragile blood vessels have formed
Weakened vessels in non-proliferative retinopathy leads to the formation of
microaneurysms
What is considered as mild NPDR
1 or more microaneurysm
What is considered as moderate NPDR
Microaneurysms
Blot haemorrhage
Hard exudates
Cotton wool spots
What are cotton wool spots
Soft exudates which represent areas of retinal infarction
What is considered as severe NPDR
Blot haemorrhages and micro aneurysms in 4 quadrants
Venous beading in at least 2 quadrants
IRMA in at least 1 quadrant
4-2-1 rule
What is venous beading
tortuosity and beading (irregular constriction and dilation) of the retinal veins
What is IRMA
abnormal branching / dilation of existing retinal vessels
What are the features of proliferative diabetic retinopathy
Retinal neovascularisation
Fibrous tissue forming anterior to retinal disc
Vitreous haemorrhage
