Flashes and Floaters Algorithm

Safety

Red flags — sight-threatening emergencies requiring same-day ophthalmology

Done

New flashes and floaters are commonly due to a posterior vitreous detachment (PVD), but not every new floater is a PVD. A clinically important minority have a retinal tear that can progress to detachment, which is treatable if caught early and a cause of permanent sight loss if missed. Screen every patient for the features below before deciding how fast they need a dilated retinal examination.

Shadow, curtain or veil in the vision Any new field defect, especially one spreading from the periphery → Same-day eye casualty (retinal detachment)

Reduced vision New blur or drop in acuity with flashes/floaters → Same day. Patient-reported reduced vision is strongly linked to a tear

Shower of floaters Sudden "soot", "cloud" or many new dots, or a red haze → Same day (vitreous haemorrhage or pigment from a tear)

Central distortion or central visual loss New central distortion, a central scotoma or sudden central visual loss → Urgent ophthalmology (same day if sudden, severe or with reduced vision; suspected wet AMD → macular service within 1 working day, NICE NG82). Consider macular hole, vitreomacular traction, cystoid macular oedema, wet AMD, retinal vascular event, or detachment involving the macula — the pathway may be macular/medical retina, but do not delay referral

Higher-risk eye High myopia, previous retinal tear or detachment in either eye, recent cataract or other intraocular surgery, eye trauma, family history of detachment, Stickler or Marfan syndrome → Lower referral threshold: refer urgently, usually within 24 hours; same day if accompanied by field loss, reduced acuity, vitreous haemorrhage, RAPD, significant trauma or rapid deterioration

Painful red eye with floaters Floaters with pain, photophobia or redness → Same day (uveitis, endophthalmitis after surgery or injection)

Recent eye surgery or intravitreal injection Pain and reduced vision are particularly concerning for endophthalmitis; new floaters alone after an intravitreal injection also need urgent contact → Same day — contact the treating eye unit directly where possible

Transient visual loss, not flashes Transient monocular visual loss (possible retinal ischaemia/amaurosis fugax) or transient homonymous field loss → Urgent vascular/TIA assessment via the local stroke pathway, to be seen by a specialist within 24 hours (NICE NG128) — not ophthalmology alone. Persistent visual loss or neurological deficit → emergency assessment (999)

Child with floaters or visual change New floaters are unusual in children → Urgent ophthalmology, usually within 24 hours — same day with visual loss, trauma or inflammation; keep the threshold low with a family history of inherited retinal disease. An absent, white or abnormal red reflex → Consider urgent referral (appointment within 2 weeks) for ophthalmological assessment for retinoblastoma; a new squint with loss of the red reflex → refer immediately (NICE NG127) — use the local paediatric ophthalmology/suspected cancer pathway and discuss urgently with the receiving service (NICE NG12, updated April 2026); not a routine optometry problem

Flashes/floaters after significant eye trauma → Same-day eye casualty

A clinically important minority of patients with acute symptomatic PVD have a retinal tear; risk varies according to the presenting population and features such as vitreous haemorrhage, pigment, trauma and reduced vision (Hollands et al., JAMA 2009). Subjective reduction in vision and a large number of new floaters raise the chance of a tear. The key surgical distinction is whether the macula is still attached. A "macula-on" detachment is operated on urgently to protect central vision; once the macula detaches, visual recovery is less complete. That is why a patient describing a shadow or curtain goes to eye casualty today, not to the next routine clinic. In an SCA consultation, ask about each red flag by name; patients rarely volunteer "a shadow" unless asked.

Diagnose

Confirm presentation — characterise flashes and floaters

Done

The description of the symptoms largely decides urgency. Take a precise history for each eye.

Floaters

One new ring, cobweb or "fly" that moves with eye movement = suggests PVD (a Weiss ring may represent condensed vitreous around the optic nerve head, but is not present in every PVD; PVD cannot be confirmed by history alone) | Many new dots or a "shower" = blood or pigment — higher risk of a tear | Long-standing, unchanged spots = benign vitreous opacities

Flashes

Brief arcs or lightning streaks, usually at the edge of vision, in one eye, more noticeable in dim light = vitreoretinal traction (PVD or tear) | Zig-zag, shimmering, spreading pattern affecting both eyes' field, lasting minutes = migraine aura

Onset

Sudden (hours to days) = acute PVD, tear, haemorrhage | Gradual or unchanged for months = benign floaters

Duration of flashes

PVD: a second or less, repeated. Typical migraine aura: develops over at least 5 minutes and lasts 5–60 minutes (NICE CG150, 2012, updated June 2025)

One eye or both

Symptoms that stay in one eye when the other is covered = eye cause. Visual phenomena present with either eye covered, or affecting the same half of vision in both eyes = brain (migraine aura, occipital lesion). Retinal photopsia is usually monocular and peripheral

Transient visual loss

Transient monocular visual loss is not a typical PVD symptom — treat as possible retinal ischaemia (amaurosis fugax). A transient homonymous field defect suggests a cerebral/vascular cause. Both → urgent vascular/TIA assessment via the local stroke pathway, to be seen by a specialist within 24 hours (NICE NG128)

Visual field and acuity

Any shadow, curtain, missing area or blur — ask directly

Risk factors

Age over about 50, short-sightedness, previous eye surgery or injury, previous tear or detachment, diabetes (vitreous haemorrhage). Anticoagulation may increase the severity of a vitreous haemorrhage but is not, by itself, a reason to assume a retinal tear or to stop anticoagulation

Other eye

Previous PVD or detachment in the fellow eye. Detachment in one eye raises the risk in the other

A single new ring-shaped floater with brief peripheral flashes is the classic story of an uncomplicated PVD. A sudden "shower" of dots is more worrying, because blood or pigment released into the vitreous is strongly associated with a retinal tear. Migraine aura is distinguished by its gradual development over at least 5 minutes, positive zig-zag phenomena, effect on both eyes' fields, duration of 5–60 minutes and full reversibility. It needs no eye referral if typical, but a first or atypical aura, aura with persistent deficit or with weakness/speech disturbance, or aura in an older person without previous migraine should not be automatically reassured — consider urgent neurological/stroke assessment according to presentation. Asking whether the symptoms persist with each eye covered separates an eye problem from a brain one within seconds.

Diagnose

Classification — benign vs sight-threatening

Done

Posterior vitreous detachment (PVD)

The commonest cause of new flashes and floaters from middle age onwards; the vitreous gel separates from the retina. Retinal tear, detachment, vitreous haemorrhage and inflammation must be excluded by dilated examination. Label as uncomplicated only after an adequate dilated retinal examination: normal acuity, no field loss, no shower, and no tear

Retinal tear

A clinically important minority of patients with acute symptomatic PVD have a retinal tear; risk varies with the presenting population and features such as vitreous haemorrhage, pigment, trauma and reduced vision. Treated by ophthalmology with laser retinopexy or cryotherapy where appropriate

Retinal detachment

Fluid passes through the tear and lifts the retina: a spreading shadow or curtain, ± reduced vision. Needs urgent vitreoretinal surgery; timing depends on whether the macula is still attached

Vitreous haemorrhage

Sudden "red haze", many dark floaters, reduced vision; poor or absent red reflex. Causes: proliferative diabetic retinopathy, retinal vein occlusion, retinal tear/detachment, trauma, posterior vitreous detachment; less commonly retinal vasculitis or haematological disease. Anticoagulation may increase severity. Acute vitreous haemorrhage with flashes/floaters needs same-day ophthalmological assessment even if the patient is anticoagulated or has known diabetes

Posterior uveitis / vitritis

Floaters with blurred vision ± pain, photophobia, red eye; may be linked to systemic inflammatory disease or infection

Benign vitreous floaters

Long-standing, stable spots or strands; normal vision and fields; no flashes. Reassure, but any change in character means reassessment

Migraine aura

Positive spreading visual disturbance affecting both eyes' fields, developing over at least 5 minutes and lasting 5–60 minutes, usually followed by headache; fully reversible (NICE CG150). First or atypical aura, persistent deficit, weakness/speech disturbance or older age without previous migraine → consider urgent neurological/stroke assessment

Macular causes

Central distortion or scotoma: macular hole, vitreomacular traction, cystoid macular oedema, wet AMD, retinal vascular event, macula-involving detachment → urgent ophthalmology (macular/medical-retina pathway; suspected wet AMD within 1 working day, NICE NG82; same day if sudden or with reduced vision)

Other mimics

Occipital lobe lesions and seizures (stereotyped coloured shapes), retinal migraine (monocular, diagnosis of exclusion), phosphenes on eye movement from optic neuritis

A retinal tear cannot be excluded without a dilated examination of the peripheral retina, which is why every new PVD needs one: from an optometrist with the right equipment, a community urgent eye service or the hospital eye service, depending on local arrangements. The College of Optometrists guidance on flashes and floaters says a patient with a confirmed PVD after dilated examination can be managed in practice, provided they are well informed about the symptoms that mean a tear or detachment has developed. Sealing a tear with laser or cryotherapy is a quick outpatient procedure, whereas a detachment needs surgery. The earlier this pathway is triggered, the more treatment options remain.

Diagnose

Targeted examination in primary care

Done

Visual acuity Essential

Snellen chart each eye separately, with glasses (or pinhole). Record the result (e.g. 6/6, 6/12). If no chart: count fingers, hand movements, perception of light

Visual fields

Confrontation for each eye separately, all four quadrants. Any defect → same-day referral. An Amsler grid is not essential in an acute flashes-and-floaters consultation and should not delay referral

Pupils

Swinging light test for a relative afferent pupillary defect — present with a large detachment or optic nerve disease and a reason for same-day referral

Red reflex

Through the direct ophthalmoscope at arm's length: a dim or absent reflex suggests vitreous haemorrhage or a dense cataract

Fundoscopy

Direct ophthalmoscopy (if competent) shows the disc and central retina only. Look for haemorrhage, a grey elevated retina, or disc swelling. A normal visual acuity, confrontation field and direct ophthalmoscopic examination do not exclude a retinal tear or early detachment. The peripheral retina needs dilated slit-lamp or indirect ophthalmoscopic examination, often with scleral indentation, in an appropriate eye service. Do not let a normal red reflex or central fundus view delay referral when the history is concerning

Anterior segment

Redness, photophobia, irregular pupil (uveitis); signs of recent surgery or trauma

BP, glucose, anticoagulation

Only when the clinical picture suggests retinal haemorrhage, diabetic retinopathy, severe hypertension or anticoagulant-related bleeding — not mandatory for every uncomplicated PVD. Do not delay ophthalmic referral to obtain these

Examination in primary care is for triage: acuity, fields and the red reflex identify who needs to be seen today. Retinal tears are usually in the far periphery. Seeing them needs pupil dilation and a slit lamp with a handheld lens or an indirect ophthalmoscope, so a normal direct fundoscopy or red reflex by a GP should never be used to reassure or to delay referral. Documenting acuity and fields at the first contact also gives the eye service a baseline and protects you if things change.

Diagnose

Investigations

Done

Dilated retinal examination Essential · eye service

Slit-lamp biomicroscopy with a fundus lens or indirect ophthalmoscopy ± scleral indentation to see the peripheral retina, by an optometrist, community urgent eye service or hospital eye service per local pathway

Vitreous pigment ("tobacco dust") Eye service

Specialist slit-lamp finding in the anterior vitreous; its presence prompts a very careful search, and its absence does not exclude a tear

B-scan ultrasound

When a vitreous haemorrhage or dense cataract blocks the view — shows whether the retina is attached. Performed in the eye service

OCT (optical coherence tomography)

Cross-sectional imaging of the macula: vitreomacular traction, macular hole, macular oedema. Many community optometrists now have OCT. Eye-service investigation; does not replace a dilated retinal examination when acute flashes/floaters are present

In primary care

Priority: visual acuity each eye (pinhole if reduced), confrontation fields, pupils/RAPD, red reflex, direct ophthalmoscopy if competent; ask about pain, redness, photophobia, recent surgery/trauma. Check BP, glucose/HbA1c and INR only when the picture suggests retinal haemorrhage, diabetic retinopathy, severe hypertension or anticoagulant-related bleeding (INR not routine for floaters). Do not delay referral for these tests

Neuroimaging

Only if symptoms are cortical rather than ocular (homonymous field loss, other neurology), arranged through the stroke or neurology pathway

Not routine

Fluorescein angiography, electrodiagnostics — specialist investigations

The one investigation that matters is a dilated peripheral retinal examination by someone equipped and trained to do it. In many areas this is now done in the community by optometrists working in a commissioned urgent eye service, with onward referral if a tear or detachment is found. Vitreous pigment is a specialist slit-lamp finding; its absence does not rule out a tear, so safety-netting still applies. Ultrasound matters when a haemorrhage hides the retina, because an unseen detachment behind the blood changes the urgency completely.

Refer

Referral criteria — emergency eye department or urgent eye service

Done

Same-day eye casualty

New field defect, curtain, veil or shadow | reduced visual acuity or new persistent blur | suspected retinal detachment | suspected vitreous haemorrhage (shower of floaters, smoke/red haze, poor or absent red reflex) | RAPD with new visual symptoms | new flashes/floaters with significant ocular trauma | painful red eye with reduced vision | recent intraocular surgery or injection with pain, reduced vision or new floaters (contact treating unit) | sudden central visual loss or severe distortion

Urgent dilated exam (usually within 24 hours)

New flashes and/or floaters without field loss, reduced acuity, vitreous haemorrhage or other red flags, including suspected acute PVD with a normal primary-care examination, and higher-risk eyes (high myopia, previous tear/detachment, fellow-eye detachment, recent intraocular surgery) with normal acuity and fields — via hospital eye casualty, a community urgent eye service, an optometrist with dilated retinal examination facilities, or local urgent eye-care pathway. The key requirement is a prompt dilated peripheral retinal examination, not a routine optometry appointment

Stroke / TIA pathway

Transient monocular visual loss, transient homonymous field loss, or any visual loss with focal neurological symptoms → urgent vascular/TIA assessment via the local stroke pathway, to be seen by a specialist within 24 hours (NICE NG128). Persistent visual loss or neurological deficit → emergency assessment (999)

Urgent ophthalmology

Children with new floaters (usually within 24 hours; same day with visual loss, trauma or inflammation); known proliferative diabetic retinopathy with new floaters (usually within 24 hours; same day with a shower, red haze or reduced vision); new central distortion or central scotoma (macular/medical-retina pathway; suspected wet AMD within 1 working day, NICE NG82; same day if sudden or with reduced vision). Suspected uveitis (pain, photophobia or redness with floaters) → same day, as in Step 1

NICE NG12 (updated April 2026) · paediatric ophthalmology

Child with an absent, white or abnormal red reflex → consider urgent referral (appointment within 2 weeks) for ophthalmological assessment for retinoblastoma; a new squint with loss of the red reflex → refer immediately (NICE NG127); use the local paediatric ophthalmology/suspected cancer pathway and discuss urgently with the receiving service

Routine optometrist

Only for long-standing, unchanged floaters with normal acuity, normal fields and no flashes — provided the history is reliable and there are no risk factors or concerning changes. Referral to ophthalmology only if symptoms severely affect quality of life despite reassurance

Reassure and safety-net

Typical migraine aura (gradual spread, both eyes' fields, 5–60 minutes, full recovery) with normal examination. Do not automatically reassure a first or atypical aura, persistent deficit, weakness/speech disturbance or an older person without previous migraine

Urgency follows risk. A shadow, reduced vision or a shower of floaters raises the probability of a tear or detachment enough to need same-day assessment. An isolated new floater with flashes still needs a dilated examination soon, because symptoms alone cannot exclude a tear. Most local pathways aim for within about 24 hours. The College of Optometrists guidance advises referral when relevant symptoms occur with any of the examination signs of a break or detachment, and supports managing a confirmed uncomplicated PVD in the community with good advice. Know your local urgent eye service: it is often the fastest route to a dilated examination.

Treat

Treatment — condition-specific

Done

Uncomplicated PVD (after dilated examination)

No treatment. Flashes usually settle over weeks; floaters become less noticeable over weeks to months as the brain adapts and the opacity moves. Normal activities can continue unless the eye service advises otherwise. Give clear written warning symptoms

Retinal tear

Laser retinopexy or cryotherapy by the eye service, usually as an outpatient, to seal the edges of the tear and prevent fluid entering. Follow-up as directed

Retinal detachment

Surgery: vitrectomy with gas or oil, scleral buckle, or pneumatic retinopexy, chosen by the surgeon. After gas: posture as instructed, no flying and no nitrous oxide anaesthesia until the gas has gone (the patient should carry the warning wristband)

Vitreous haemorrhage

Treat the cause: laser for proliferative diabetic retinopathy, anti-VEGF injections in some cases; vitrectomy if it fails to clear or the retina is threatened. Do not stop warfarin, DOACs or antiplatelets in primary care solely because of new floaters or vitreous haemorrhage — the eye team and the anticoagulation prescriber make an individualised decision

Uveitis

Specialist-led topical or systemic treatment; investigate for associated systemic disease

Persistent troublesome floaters

Most people adapt. Vitrectomy for floaters is reserved for severe, persistent symptoms because of its risks (cataract, retinal tear, retinal detachment). YAG vitreolysis is not routine treatment and should only be considered by appropriately experienced retinal specialists after discussion of uncertain benefit and potential retinal/intraocular risks (NICE HTG644)

Migraine aura

Manage migraine per NICE CG150 (see headache guidance). Cross-reference: migraine with aura affects contraceptive choice (UKMEC)

Next steps: see Migraine · Stroke and TIA · Uveitis

Treatment of tears and detachments is entirely specialist-led. The GP's contribution is speed of referral and good advice. The practical points that matter in primary care are that people with intraocular gas must not fly or have nitrous oxide until the gas has absorbed, and that anticoagulants should not be stopped without discussion. Reassurance for uncomplicated PVD works best when it is paired with specific warning symptoms. "Nothing to worry about" on its own can delay a patient returning when a tear develops later.

Lifestyle

Prevention and risk reduction for high-risk patients

Done

Diabetic eye screening Make sure everyone with diabetes aged 12+ attends the NHS Diabetic Eye Screening Programme (recall interval depends on the screening result and programme criteria) and routine diabetes care. Proliferative retinopathy is a preventable cause of vitreous haemorrhage

Glycaemic and BP control Individualised HbA1c targets (NICE NG28 / NG17) and BP targets (NICE NG136) reduce progression of diabetic retinopathy

High myopia Optometrist reviews as individually advised; teach the warning symptoms (shadow, curtain, shower of floaters) and where to go out of hours

After cataract surgery The risk of detachment is raised after intraocular surgery; reinforce the eye unit's discharge advice about sudden floaters, flashes or a shadow

Eye protection Protective eyewear for racquet sports, DIY, power tools and contact sports, especially in myopic eyes or after previous retinal problems

Smoking cessation Smoking is a risk factor for age-related macular degeneration and vascular eye disease; offer a stop-smoking service referral (NICE NG209, 2021)

Driving Do not drive if vision is acutely impaired or the visual field is affected; follow DVLA guidance — drivers must meet the DVLA visual acuity and field standards, and some conditions must be notified to DVLA

Anticoagulants Do not stop anticoagulant or antiplatelet medication to reduce vitreous haemorrhage risk without specialist advice

Regular sight tests NHS sight tests are free for many groups, including people aged 60+ and people with diabetes or glaucoma

Most PVDs cannot be prevented, so prevention here means preventing the sight-threatening complications of other conditions and making sure high-risk patients present early. Diabetic eye screening detects retinopathy before symptoms develop, and good glycaemic and BP control slows progression. The best protection against losing sight from a detachment is a patient who recognises the warning symptoms and knows where to go out of hours. Driving advice matters because a reduction in acuity or field may fall below the DVLA standard.

Safety

Follow-up and safety-netting

Done

After the eye assessment

Record the findings and plan in the notes; make sure the patient understands whether follow-up is booked and why

The next few weeks

A retinal tear can rarely develop after an initially negative examination, particularly in the first several weeks. Follow the eye service's review plan. Any new shower of floaters, increased flashes, reduced vision, field defect or curtain requires immediate reassessment

Planned review

Follow-up timing is set by the examining eye service. Some re-examine high-risk PVDs (e.g. with vitreous haemorrhage or pigment) at a few weeks; not every uncomplicated PVD needs a routine six-week review if appropriate safety-netting has been given — local protocols vary

Same day / out of hours

"A shadow or curtain, a sudden shower of new floaters, more flashes, or blurred vision — go to eye casualty or call NHS 111 straight away, even at night or at the weekend. Don't wait for a GP appointment."

Contact the same day

Symptoms starting in the other eye; floaters that change in character; new distortion of straight lines → urgent eye assessment, usually within 24 hours (go straight to eye casualty for any of the symptoms above)

Fellow eye

A PVD in one eye is commonly followed by one in the other eye, and a detachment in one eye raises the risk in the other. Explain that the same warning signs apply to both eyes

Written advice

Give clear written warning symptoms, local eye-casualty contact details and out-of-hours instructions, and advise not to wait for a routine GP appointment; document that you did

A retinal tear can rarely develop in the weeks after an apparently uncomplicated PVD (Hollands et al., JAMA 2009, in patients initially assessed in eye services). That is why the safety-net matters more than any single follow-up appointment. The College of Optometrists guidance makes good patient information a condition of managing PVD in the community. Naming the exact symptoms (shadow, curtain, shower, blur) and where to go out of hours gives the patient a plan they can act on. Documenting that advice is the medicolegal safeguard.