01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Begin by translating the patient's description into a visual phenomenon. A floater moves relative to the scene and may lag after an eye movement; a field defect remains in a particular part of the visual field. A brief flash at the edge of one eye suggests a different process from an expanding zigzag pattern that is present with either eye covered. Ask the patient to cover each eye in turn during an ongoing symptom where practical. People often use one side of vision and one eye interchangeably, which can misdirect localisation.
The first assessment must determine whether urgent action is needed before a complete diagnosis is possible. A curtain, missing vision, a sudden dense shower of dots or a relevant injury raises concern for retinal detachment or haemorrhage. A quiet, white, painless eye provides little reassurance about these posterior-segment conditions. Ask for the exact time of the newest change, because a longstanding floater followed by a new shadow is not simply a longstanding presentation. If current symptoms suggest threatened vision, contact the receiving service while examination proceeds.
A practical history includes previous retinal tears, detachment in either eye, high myopia, cataract or other intraocular surgery, blunt or penetrating injury and relevant systemic disease. Diabetes makes proliferative retinopathy and bleeding plausible, but does not exclude a retinal tear. Antithrombotic treatment may influence bleeding and procedural planning without establishing its cause. Review pain, redness and photophobia because these can redirect attention towards inflammation or other ocular disease. Ask about neurological symptoms when the reported visual disturbance might represent a brain or vascular event.
An adequate examination is a process with a documented endpoint. Assess acuity before dilation when possible, inspect pupils and compare fields, then assess the vitreous and retina using suitable equipment. A clinician with the necessary training examines the dilated periphery, adding techniques such as indentation where indicated. Explain discomfort, light sensitivity and temporary blur, and obtain consent. If the patient cannot cooperate or the view is obscured, record what remains unknown and arrange further assessment. Writing fundus normal after a limited central view can conceal an important diagnostic gap.
Key points
- Clarify whether the symptom is a moving opacity, a flash, a fixed blind area or a gradually spreading visual pattern.
- Establish onset, progression, eye involved and associated visual loss, then ask about myopia, trauma, surgery and previous retinal disease.
- Measure each eye's acuity, compare pupils and screen fields without using normal findings to exclude a peripheral tear.
- Suspected retinal breaks require examination of the anterior vitreous and dilated fundal assessment with an indirect viewing technique.
- Central OCT, an ordinary fundus photograph and an undilated direct ophthalmoscope do not replace an adequate peripheral retinal examination.
- Document the examination's completeness and provide specific written instructions for urgent reassessment if symptoms change.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
Ask whether the perceived mark drifts with gaze or remains as a curtain or missing area. A fixed defect carries a different implication from a stable isolated vitreous opacity.
Sudden monocular photopsia, numerous new floaters or a new peripheral shadow suggests a vitreoretinal event. The number of symptoms should guide urgency without becoming an unsupported numerical rule.
Pigment cells in the anterior vitreous or blood obscuring the fundus raises concern for a retinal break. These findings require urgent specialist interpretation even if no break is seen immediately.
Gradually spreading binocular patterns may suggest cortical aura, while abrupt negative visual loss or associated neurological deficits needs a vascular or neurological pathway. Clarify laterality before choosing the destination.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Monocular acuity, pupils and confrontation fieldsFirst step - Why
- Document visual function and detect an obvious afferent or field abnormality.
- Interpretation and limitations
- Record correction and baseline comparison. Preserved reading acuity cannot exclude a peripheral tear, and a normal confrontation test lacks the sensitivity to certify a normal retina.
- 02
Anterior vitreous examination at the slit lamp - Why
- Identify pigment, haemorrhage and evidence of vitreous separation.
- Interpretation and limitations
- Pigment supports an urgent retinal-break assessment. A Weiss ring may be absent despite a PVD or tear, so its absence should not end the investigation.
- 03
Dilated peripheral retinal examination - Why
- Identify a retinal break, detachment or alternative posterior pathology.
- Interpretation and limitations
- Use indirect viewing within competence, with specialist peripheral examination as needed. Document sectors obscured by media opacity or poor cooperation and ensure unresolved uncertainty has a follow-up plan.
- 04
Selective posterior-segment imaging - Why
- Answer a specific question not resolved by the clinical view.
- Interpretation and limitations
- Ultrasound helps when the fundus is obscured, while OCT assesses the macula and vitreomacular interface. An image centred on the macula cannot exclude a tear outside its scanned region.
04Clinical next stepsHow the result changes management or prompts escalation.
01Triage at first contactIdentify the need for emergency assessmentFirst stepThe patient contacts a service because visual phenomena are new or have changed.+
- 1Ask immediately about a curtain, visual decline, a sudden shower, injury and the time of the most recent change.
- 2EscalationArrange emergency same-day ophthalmic assessment for threatened retinal function; staff should have a clear escalation route rather than attempting a telephone diagnosis.
- 3For new isolated flashes or floaters, arrange prompt examination through the local urgent eye pathway and give immediate return instructions if a shadow or visual loss develops.
02Examination sequenceAssess the vitreous and peripheral retinaThe clinician has appropriate equipment and training to investigate the current symptoms.+
- 1Measure acuity and record pupil and field findings before dilation when feasible, explaining the examination and relevant post-dilation precautions.
- 2Examine the anterior vitreous and conduct an adequate dilated indirect retinal examination, documenting the structures actually visualised.
- 3EscalationEscalate pigment, blood, symptomatic breaks or detachment; seek further assessment when the examination cannot establish a sufficiently reliable conclusion.
03After a reassuring assessmentGive an explicit diagnosis and safety planThe current episode has been adequately examined without a sight-threatening retinal finding.+
- 1Explain the identified cause and distinguish stable expected symptoms from a sudden increase, fixed shadow or reduction in vision.
- 2Record whether a planned review is needed and make clear that new warning symptoms require earlier reassessment.
- 3Give written advice and an accessible contact route, checking that the patient understands where to go outside ordinary clinic hours.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Record symptom onset and the date of any important subsequent change so that another clinician can distinguish an evolving event from persistent stable symptoms.
- Describe the retinal examination method and its limitations; avoid converting uncertainty into a normal result through a generic template entry.
- Check that an emergency referral has been received and has a practical destination, especially when the patient needs transport or cannot navigate the service independently.
- If symptoms change after discharge, reassess the urgency from the new presentation instead of relying on the previous reassuring label.
- Advise against driving while vision is affected by symptoms or dilation, and arrange safe travel home when an examination temporarily blurs vision.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
An inadequate view is a finding
Dense cataract, haemorrhage, a small pupil or poor cooperation can prevent exclusion of retinal pathology. The record should identify the limitation and the action needed to resolve it.
Peripheral methods can change detection
A UK prospective community-referral study found retinal tears visible on indentation indirect examination that were not seen with slit-lamp biomicroscopy alone. This supports a careful peripheral assessment rather than reliance on one reassuring central view.
The fellow eye adds context
Previous disease and current symptoms in the other eye affect risk and practical safety. Examine and document each eye as appropriate rather than assuming identical anatomy or visual reserve.
Telephone advice cannot confirm PVD
Descriptions can prioritise the appointment but cannot establish the condition of the retina. Support staff need a route to clinical triage and should avoid promising a benign diagnosis before examination.
07Common pitfallsFrequent interpretation and management errors.
- 01
Asking only how long floaters have existed and overlooking the onset of a new shadow or new visual decline.
- 02
Assuming a white painless eye cannot have a sight-threatening posterior-segment disorder.
- 03
Using a normal central OCT or photograph as evidence that the far peripheral retina has no break.
- 04
Sending an urgent referral without telling the patient its urgency, destination and what to do if the expected contact does not occur.