Loss of Vision Flashcards

Question

Acute Transient Visual Loss Causes

Answer 1

* Monocular ischaemia, carotid disease, other embolic source * Giant cell arteritis * Papilloedema * Idiopathic retinal vasospasm * Migraine * Vertebrobasilar ischaemia * Seizure : Ictal * Postictal

Answer 2

* Cataracts * Chronic glaucoma * Trachoma * Macula degeneration * Presbyopia * Diabetic retinopathy

Answer 3

Definition A cataract is an opacity of the lens of the eye that causes partial or total blindness, 50% of world blindness may be due to this Pathophysiology Unlike epithelia, the less does not shed its nonviable cells, hence there is a build-up of proteins causing lens opacity. The exact mechanism is not known. Most cases occur in those > 60 years of age. Risk factors Age, smoking, alcohol, metabolic syndrome, diabetes mellitus.

Answer 4

Presentation The vast majority are senile or age-related with a few for acquired cataracts. The development of age-related cataracts is painless, progressive and can be highly variable. Typically it is bilateral although it can be monocular. Patients usually complain of night driving, reading road signs or difficulty with fine print. Investigations A lens opacity can be confirmed by non dilated fundus examination with ophthalmoscope; there may be darkening of red reflex, opacities within red reflex or obscuration of ocular fundus examination. Treatment Cataract surgery is the only treatment and the opacified lens is surgically removed. It is a low-risk procedure and should be sought when there is interference in the ability of daily living.

Answer 5

Definition Glaucoma is a group of eye diseases that are traditionally characterised by the intraocular pressure (IOP) exceeding optic nerve threshold. Usually due to a raised IOP. Pathophysiology Excessive IOP leads to optic nerve damage and consequent visual loss. Can be primary or secondary to uveitis, trauma, glucocorticoid therapy, vasoproliferative retinopathy or ocular syndromes Classification Defined as open-angle or angle-closure. * Open-angle is characterised by progressive peripheral visual field loss, followed by central field loss. It is associated with increased aqueous production and decreased outflow. * Angle-closure is where the drainage pathway of aqueous humour is blocked with anatomical predisposition

Answer 6

Presentation In open angle there are rarely symptoms. The visual loss occurs but the painful red eye is only a presentation of angle-closure. Diagnosis Nerve damage on fundus examination, visual field testing and elevated IOP. Investigations Gonioscopy is the gold-standard using a special lens for a slit lamp to visualise the angle and diagnose angle closure. Treatment Immediate laser iridotomy, decreases IOP (topical beta-blockers, adrenergics, carbonic anhydrase, hyperosmotic agents) and miotic drops (pilocarpine).

Answer 7

Definition Trochoma is a contagious eye infection of Chlamydia trachomatis and is the leading cause of worldwide blindness. C. trachomatis is transmitted by intimate social or sexual contact. Presentation The manifestations can be divided into two phases: * Active trochoma - causes a mild, self-limited follicular conjunctivitis (relatively asymptomatic) usually in childhood. * Cicatricial disease - causes scar tissue leading to entropion (inward rolling of the eyelid) and subsequent trichiasis (ingrown eyelashes). Eyelash abrasion on the cornea leads to corneal oedema, ulceration and scarring. If untreated this results in blindness. Investigations PCR of swab ``` Treatment Surgery (reduce eyelash irritation), Antibiotics (azithromycin), Facial cleanliness and Environmental improvement is the tool for global trachoma elimination. (F & E reduce transmission) ```

Answer 8

Definition Age-realted macula degeneration is a degenerative disease of the central portion of the retina (the macula) that results in primarily in loss of central vision. It is classified as dry (atrophic) or wet (neovascular or exudative) for clinical purposes. Epidemiology Of those > 40yo the prevalence is 1.5%. Risk factors include age and smoking Presentation * Dry (atrophic) * Gradual loss of vision in one or both eyes. * Wet (neovascular or exudative) * Acute distortion in vision, especially straight lines or loss of central vision usually in one eye, may be acute. Investigations On fundus examination: Dry (right) - small, bright drusen are visible Wet (left) - areas of vessel leakage are present with large disci form scar Treatment Complicated. Stop smoking. If there is wet degeneration then laser the new blood vessels

Answer 9

Definition Presbyopia “ageing sight” is a non-refractive error that also affects visual acuity. Pathophysiology Occurs when the lens loses its normal accommodating power and can no longer focus on objects viewed at arms length or closer. The cause of accommodation loss includes increased form deprivation, excessive accommodation, scleral stretching (second to raised IOP) and autonomic deficits. Presentation It begins after age 40 when the patient starts to appreciate the inability to focus objects at reading distance. The eye’s focusing power for reading is lost progressively and fully by 65. Treatment Corrective lenses

Answer 10

Definition Diabetic retinopathy is a global term for vision loss secondary to macular oedema (retinal thickening and oedema involving the macula), haemorrhage from new vessels, retinal detachment or neovascular glaucoma. Classification Termed non-proliferative or proliferative (presence of abnormal new blood vessels emanating from the retina) Aetiology Chronic hyperglycaemia. It is not sure how. VEGF? Presentation The vast majority have no symptoms until late stages * Non-proliferative (left) - has variable nerve-fibre layer infarcts (cotton wool spots), intraretinal haemorrhages and hard exudates * Proliferative (right) - has neovascularisation arising from the disc and/or retinal vessels. Prevention Good glycaemic and blood pressure control

Loss of Vision Flashcards

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