Loss of Vision

Loss of Vision

·        Is it bilateral or unilateral?

·        Sudden: Woke up with it Þ Vascular: Central retinal artery or vein occlusion, ischaemic optic neuropathy, vitreous haemorrhage, CVA, preretinal haemorrhage

·        Suddenish: Gradual over a few days: Closed angle glaucoma (hours), infection, inflammation, retinal detachment, optic neuritis

·        Gradual: Months to Years: Refractive, cataract, primary open angle glaucoma, age related macular degeneration, retinopathy (eg diabetes, hypertension)

·        Chronic visual loss:

Age Related Macular Degeneration

·        Loss of visual acuity with peripheral vision in tact

·        Observe stippling and depigmentation of macular

·        Can be uni or bilateral

·        Age-related types:

o   Dry (atrophic) macular degeneration: thinning of macula, gradual. No cure. Atrophy of photoreceptors, loss of outer nuclear layer

o   Wet (exudative) macular degeneration: May be due to Choroidal Neovascular Membranes, unilateral with onset over several weeks. Straight lines appear wavy ® refer as laser treatment slows progression

·        Symptoms: blurred central vision, distortion of straight lines

Eye Trauma

·        Mechanical: blunt/sharp, superficial/penetrating

·        Chemical: alkali the worst. Local anaesthetic then irrigate for 30 minutes (less time already irrigated before presentation). If not toxic nor significantly inflamed, if VA OK and no fluorescein staining then chloramphenicol eyedrops qid for 5 days

·        Radiation: UV, thermal, arch flash. Comes on hours after exposure, is very painful. Eye is very red, multiple fine specks of fluorescein staining. Usually resolves in 24 hours. Treat as an abrasion (pad both eyes)

·        Hyphema: blood in anterior chamber. Refer for opinion but don‟t normally treat. Check for corneal abrasion, traumatic mydriasis, eye movements, blowout fracture of orbital floor, intra-ocular bleed

·        Penetrating Eye Injuries can be missed by subconjunctival bleed. Always refer if at risk. If metal vs. metal, always do an xray otherwise blind from Fe toxicity. Also rose thorns. Teardrop shaped cornea is a PEI until proven otherwise. Refer immediately. Lie down, im antiemetic to prevent vomiting.

·        Keep nil-by-mouth

·        Distorted pupil: penetrating injury until proven otherwise Þ nil by mouth, shield eye, antibiotics, antiemetic, refer

·        Foreign bodies: remove with 25-gauge needle and topical anaesthetic drops. Steady fixation of eye is key. Always evert upper key lid to look for further foreign bodies

·        Corneal abrasions: Very painful and photophobic. Stain with fluorescein. Most heal within 24 hours. Refer if abrasion large or central, if cornea hazy, VA reduced or eye is very inflamed. Double pad eye well. Apply chloramphenicol ointment stat and bd for 5 days. Never give anaesthetic drops to take home – can cause ulceration and blindness

·        Lid laceration: sow up anything not penetrating, or not involving lid margin or tear drainage (refer these)

Retinal Detachment

·        Higher risk in near-sighted (myopic)

·        Can be caused by blunt trauma

·        Due to vitreous shrinkage, tears/holes in retina (eg with age), or underlying pathology

·        Symptoms: sudden changes in vision – watery or shadowy patch, sudden ­ in number of floaters (spots in vision), loss of visual field (like a descending curtain)

·        Need rapid treatment: seal tear with laser

·        Causes:

o   Exudative detachment: accumulation of fluid under the retina due to leaky vessels, eg tumour, vascular abnormality

o   Traction detachment: vitreous becomes organised following trauma or neovascularisation and pulls on the retina