Altered vision and retinal disease

Establish the pattern

Ask whether visual loss is sudden or gradual, monocular or binocular, painful or painless, and persistent or episodic. Document visual acuity in each eye, using usual correction and a pinhole where appropriate, before treatments obscure findings. Assess pupils, relative afferent pupillary defect, fields and ocular movements, with fundoscopy when feasible. Symptoms described as “blur” can reflect refractive error, cataract, corneal disease, retinal pathology or a central neurological lesion. Sudden loss needs urgent assessment even when the eye appears externally normal.

Transient monocular loss can be retinal ischaemia and warrants urgent vascular/stroke evaluation. A homonymous field defect suggests a post-chiasmal lesion rather than disease in one eye. Migraine aura often evolves with positive symptoms, but a first atypical event or persistent deficit requires assessment. Diplopia disappearing when either eye is closed is binocular and suggests ocular misalignment; new diplopia with neurological signs is urgent. Monocular diplopia more often reflects an ocular optical problem, although the full clinical context still matters.

Retinal vascular emergencies

Sudden painless profound monocular loss raises retinal artery occlusion. Treat it as a time-sensitive eye and vascular emergency, with urgent ophthalmology/stroke input. Retinal whitening and a cherry-red spot can support the diagnosis, but an inexperienced or apparently normal fundus examination should not delay referral. Assess embolic risks and, in older people, symptoms of giant cell arteritis such as jaw claudication and new headache. GCA requires immediate treatment when vision is threatened; waiting for inflammatory markers or biopsy can allow loss in the other eye.

Retinal vein occlusion can cause painless blurred vision with retinal haemorrhages and venous changes. It also requires ophthalmological assessment and review of vascular risks, but its treatment is not simply the arterial-occlusion pathway. Do not prescribe anticoagulation to every retinal haemorrhage without a separate indication. Diabetic retinopathy can progress silently; organised eye review, glucose/BP management and timely specialist treatment reduce loss. New floaters or blur in diabetes may reflect vitreous haemorrhage or traction and requires symptom assessment rather than waiting for the next screening visit.

Flashes, floaters and a curtain

New flashes and floaters can occur with posterior vitreous detachment but can also signal a retinal tear. A dark curtain, field loss, reduced vision or a high-risk history increases concern for detachment. Arrange prompt dilated retinal assessment; direct fundoscopy alone cannot reliably exclude a peripheral tear. Ask about myopia, trauma, prior eye surgery and previous detachment. Explain return precautions after an initial reassuring examination because a tear may develop later. A patient should not be told to wait weeks merely because floaters are common with ageing.

Macular disease typically affects central detail, reading or facial recognition while peripheral vision may remain. New distortion, such as straight lines becoming bent, or a central scotoma merits prompt assessment for neovascular age-related macular degeneration and other macular causes. Intravitreal treatment can preserve vision in appropriate disease; delays matter. Distinguish symptom-driven assessment from routine monitoring of stable dry disease. Offer smoking cessation and visual aids/support as appropriate, rather than implying that age makes loss untreatable or inconsequential.

Gradual loss and function

Cataract can produce gradual blur, glare and reduced contrast. Evaluate the functional impact on reading, work, mobility and driving; the decision for surgery involves symptoms and preferences rather than one universal acuity cut-off. Glaucoma can cause irreversible optic-nerve and field damage while early central acuity stays normal. Chronic disease needs ophthalmological pressure/nerve/field assessment and adherence support. Acute painful angle closure is a separate emergency, covered in red-eye assessment. Normal intraocular pressure at one visit does not exclude every glaucoma phenotype.

Check whether the person can administer eye drops, afford treatment and attend follow-up. Offer techniques and supports for arthritis, cognitive impairment or visual disability. Low vision can contribute to falls, medication errors, loneliness and apparent cognitive difficulty. Explain findings in accessible formats, ask permission before guiding a visually impaired person, and involve occupational or low-vision services when needed. An eye diagnosis should not eclipse an associated systemic illness or vascular risk requiring coordinated care.

Exam applications

A sixty-eight-year-old notices a painless black curtain across one eye after flashes. Urgent retinal assessment is appropriate; prescribing glasses or waiting for a routine optometry appointment misses possible detachment. A patient with sudden monocular loss and jaw claudication needs immediate GCA/vascular assessment, even if the eye is white. A patient with slowly progressive glare and difficulty driving at night can be assessed for cataract and functional treatment options. These distinctions depend on tempo, field pattern and associated features, not whether pain is present.

Document acuity and the time course clearly in the referral, including the affected eye, pupillary findings, examination limits and systemic red flags. Confirm that the receiving service can review within the required urgency. A written referral without a workable appointment is not a completed emergency handover. Explain what symptoms require immediate return and check the patient's transport and support needs.

NSW Eye Emergency Manual.

Review checkpoints

• Sudden visual loss requires urgent assessment even when painless.
• Flashes, new floaters and a curtain-like field defect raise concern for retinal detachment.
• Suspected giant cell arteritis with visual symptoms needs immediate treatment and specialist care.