Patient guide · Ophthalmology
Ophthalmic diagnostic testing, the modern menu — OCT, visual fields, fundus photography, biometry, corneal topography.
In plain English: a modern eye check-up uses several small scans to look at the front and back of your eye. Together, they can spot common problems early — such as glaucoma, macular disease, diabetic eye changes and corneal conditions — and help plan any treatment or surgery you may need.
The core tools are OCT (optical coherence tomography — a scan that shows the layers at the back of your eye), a visual field test (checks your side vision), fundus photography (a detailed photo of the retina), corneal topography (a map of the front of the eye), biometry (measurements for cataract surgery) and specular microscopy (looks at the corneal cells).
Why patients choose us
- 01
The right hands
A consultant ophthalmologist runs the tests and writes the report. One clinician, one clear answer.
- 02
Often answers same-day
The consultant usually talks you through the findings straight after the tests. A written report follows shortly after.
- 03
Independent, and free
No clinic pays us. Our recommendation is impartial, and it costs you nothing.
Key facts
Ophthalmic diagnostics at a glance.
Six things worth knowing before you scroll further. What the tests are, what OCT does, what perimetry checks, what fundus photography records, what biometry measures, and who signs off the report.
- 01
Definition
A set of eye scans and tests — OCT, perimetry, fundus photography, biometry, topography and specular microscopy. A consultant ophthalmologist orders them and reads the results.
- 02
OCT is standard
OCT (optical coherence tomography) is the standard scan for the retina and optic nerve. It shows the layers at the back of the eye in fine detail.
- 03
Perimetry maps the field
A visual field test (perimetry) checks your side vision. It maps blind spots caused by glaucoma, nerve problems and retinal disease.
- 04
Fundus photography
A high-resolution photo of the retina. It records what your retina looks like now, so any change can be spotted at your next visit — and it is used in diabetic screening.
- 05
Biometry for cataract
Optical biometry measures the eye. It works out the correct lens power (IOL) for cataract surgery.
- 06
Consultant reported
A consultant ophthalmologist writes every report. A trainee never signs it off alone.
Diagnosis pathway
From consultation to report — what happens, in order.
One consultant ophthalmologist looks after you from the first appointment to the written report. This is usually done within a week.
Phase 1 · Before your tests
Consultation and planning
Phase 2 · On the day
Acuity, IOP, imaging, fields
Phase 3 · After
Report and follow-up
- 01
Before
Ophthalmology consultation
A consultant ophthalmologist reviews your symptoms, medicines, family history and any past scans. They then choose the right tests for you.
- 02
On the day
Best-corrected visual acuity
A standard sight chart is read with your current glasses. This gives the baseline number for every future visit.
- 03
On the day
IOP measurement
The pressure inside your eye (IOP) is measured with a Goldmann probe or a puff of air. It is the cornerstone of glaucoma assessment.
- 04
On the day
OCT of macula and optic nerve
OCT scans the retina and the retinal nerve fibre layer. It measures the thinning seen in AMD, diabetic macular oedema (DMO) and glaucoma.
- 05
On the day
Visual field perimetry
A Humphrey or Octopus perimeter maps your side vision. It picks up gaps caused by glaucoma, optic nerve disease and neurological problems.
- 06
On the day
Fundus photography
A high-resolution colour photo of the retina — and, when needed, an ultra-widefield photo. It records what your retina looks like today for future comparison.
- 07
After
Structured report
A consultant writes a full report with images, key measurements and clear next steps. It usually reaches you within 48 hours.
Typical end-to-end: 3–7 days. Urgent cases: same day.
What it shows
What ophthalmic diagnostics can find, in one visit.
The conditions these tests are designed to spot. The red-flag pathway is called out separately.
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Glaucoma (RNFL thinning on OCT)
OCT measures thinning of the retinal nerve fibre layer (RNFL). We read it alongside your visual field and eye pressure (IOP).
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Age-related macular degeneration
OCT and fundus photos show the drusen, pigment changes and new blood vessels seen in AMD.
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Diabetic retinopathy
Fundus imaging and OCT-angiography pick up microaneurysms, bleeding and abnormal new vessels in the retina.
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Diabetic macular oedema
OCT measures fluid in the retina and the thickness of the central macula. This guides anti-VEGF injection treatment.
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Optic neuritis
OCT shows swelling of the optic nerve and, later, thinning of the nerve fibre layer. Visual field tests confirm the pattern.
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Corneal ectasia (keratoconus)
Corneal topography and tomography map the shape of the cornea. They pick up irregular astigmatism and progressive thinning.
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Astigmatism (topography)
Regular and irregular astigmatism are mapped in detail. The map guides refractive surgery and contact-lens fitting.
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Red flag: sudden vision loss — same-day ophthalmology
Sudden loss of vision is an eye emergency. See an ophthalmologist the same day — do not wait for a routine slot.
Next steps
What happens after the tests.
The eight most common next steps. These range from reassurance and eye drops to anti-VEGF injections, laser, cross-linking, refractive planning and cataract surgery.
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Reassurance if normal
A normal, thorough eye assessment is meaningful. It is often the answer patients most need to hear.
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Glaucoma drops
First-line prostaglandin analogue eye drops lower the pressure in your eye. This helps protect your side vision.
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Anti-VEGF injections
Anti-VEGF injections into the eye treat wet AMD and diabetic macular oedema. OCT is used to guide each dose.
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Laser photocoagulation for DR
Pan-retinal laser treatment is used for advanced (proliferative) diabetic retinopathy. It stabilises the abnormal new vessels.
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Corneal cross-linking
Riboflavin drops with UV-A light strengthen the cornea. This halts the progression of keratoconus and other corneal ectasia.
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Refractive surgery planning
Topography, tomography and biometry guide planning for LASIK, SMILE, PRK and implantable contact lenses.
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Cataract surgery with toric IOL
Optical biometry works out the correct lens power. This delivers a refractive-quality cataract operation.
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Structured follow-up
Repeat OCT, perimetry and fundus photos are booked at set intervals. This follows British and European ophthalmology guidance.
Red flags
When ophthalmic assessment shouldn’t wait.
Nine situations that push ophthalmology up the queue. Some go straight to same-day emergency care.
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Sudden vision loss
Any sudden, painless loss of vision needs same-day ophthalmology or A&E — not a routine slot.
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Retinal detachment features
New floaters, flashes of light, or a curtain across your vision. You need an urgent vitreoretinal review.
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Wet AMD (rapid distortion)
New wavy or distorted central vision (metamorphopsia), or a central blind spot. This warrants an urgent macular clinic review.
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Optic neuritis
Painful loss of vision with faded colour vision. You need an urgent neuro-ophthalmology review and an MRI.
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Giant cell arteritis
Headache, jaw pain on chewing and visual symptoms in someone over 50. Get same-day blood tests (ESR/CRP) and steroids.
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Diabetic macular oedema
Reduced vision with central thickening on OCT in someone with diabetes. You need an urgent medical retina review.
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Angle-closure glaucoma
Severe eye pain, a red eye, halos around lights and vomiting. This is a same-day ophthalmology emergency.
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Endophthalmitis
Fast-worsening pain and vision after eye surgery or an injection. This is a same-day emergency.
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Recent CVA with visual field defect
A new matching (homonymous) field gap after a stroke. You need the urgent stroke pathway and neuro-ophthalmology.
Reading your report
An ophthalmology report can look intimidating. It isn’t.
Whatever the finding, the report keeps to the same four parts.
A quiet reminder
The report is written for your doctor, not for you — and that’s normal.
If you would like us to talk you through it before your follow-up, just ask.
- 01 Header
Indication and history
Your details, the reason for testing, and the eye and general health background used to interpret the scans.
- 02 Technique
Tests performed and quality
Which tests were done (OCT, perimetry, fundus photography, biometry, topography), how good the scan quality was, and any limits to note.
- 03 Findings
Quantitative metrics and images
Key numbers — RNFL thickness, macular volume, IOP, visual field indices (MD, PSD), biometry and topography maps — with labelled images.
- 04 Impression
The conclusion — read this first
The diagnosis, how severe it is, and the concrete next step: a follow-up date, treatment, or a referral.
Recognised by major UK insurers
Cover depends on your policy and clinic; we confirm with your insurer before booking.
Frequently asked
Everything we get asked about ophthalmic diagnostic testing.
Quick answers on which test you need, whether it hurts, whether your pupils will be dilated, how quickly results come back, and when to be seen urgently.
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What is ophthalmic diagnostic testing?
It is a set of tests used by a consultant ophthalmologist to diagnose and monitor eye disease. The core tests are OCT (a detailed scan of the retina and optic nerve), a visual field test (perimetry — checks your side vision), fundus photography (a photo of the retina), corneal topography (a map of the front of the eye), optical biometry (measurements for cataract surgery) and specular microscopy (looks at the corneal cells).
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Which test do I need?
It depends on the question we are trying to answer. OCT and visual field tests are the main tools for glaucoma and macular disease. Fundus photography is used for diabetic eye disease and for keeping a record. Biometry is used to plan cataract surgery. Topography is used for keratoconus and refractive surgery. A consultant ophthalmology appointment decides the right set of tests for you.
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Do the tests hurt?
No. OCT, fundus photography, perimetry, biometry and topography are all painless and do not touch the eye. Tonometry (the eye-pressure test) is either non-contact or uses a small anaesthetic drop — again, painless.
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Will my pupils be dilated?
Often, yes. Dilating drops open the pupil and give a fuller view of the retina, along with better OCT and fundus images. Your vision will be blurred for three to four hours afterwards, and bright light will feel uncomfortable. Do not drive after dilation, and bring sunglasses.
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How quickly do I get results?
The consultant usually talks you through the findings straight after the tests. A full written report follows within 48 hours, with images and key measurements you can share with your other doctors.
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When should I be seen urgently?
Get same-day care — either a same-day ophthalmology service or A&E — if you have any of these: sudden vision loss, new floaters or flashes, a curtain across your vision, a painful red eye with halos around lights, or new distortion of your central vision. Do not wait for a routine appointment.
Sources
The guidance behind this guide.
- Royal College of Ophthalmologists. Clinical guidelines.
- American Academy of Ophthalmology. Preferred Practice Patterns.
- European Society of Retina Specialists. Clinical guidelines.
- European Glaucoma Society. Terminology and guidelines for glaucoma.
Reviewed 2026-07-30 by Pulse Atlas Editorial Board, . Next review 2027-07-30. Estimated reading time 6 minutes.
Related tests
Looking for a different test?
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Optical coherence tomography
Cross-sectional imaging of the retina and optic nerve.
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Astigmatism assessment
Topography and refractive assessment for regular and irregular astigmatism.
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Cataract surgery
Biometry, IOL planning and modern cataract surgery.
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All tests
Browse every test and procedure we arrange.
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Cataracts
Related condition guide.
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Glaucoma
Related condition guide.
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Cornea Transplant
Related treatment option.
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Corneal Crosslinking
Related treatment option.
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In practice, in London
Where ophthalmic diagnostic testing sits in a private London pathway
With ophthalmic diagnostic testing, the London question is usually about turnaround. Who reads the scan, and how quickly? Availability is rarely the problem. NHS waits for ophthalmic diagnostic testing vary widely by borough and by how the GP letter reads. Privately in London, we can normally offer a slot inside the same week — sometimes within 48 hours if there’s a cancellation. The difference isn’t clinical quality; the consultants are often the same faces you’d see on the NHS. It’s the calendar.
A typical private booking in London starts with a consultant conversation. That can be in person on Harley Street or Marylebone, or on video if that suits you better. Any imaging is done at a nearby CQC-registered facility. Reports usually land within 24 to 72 hours. The whole loop, from first call to written report, is often done inside a fortnight. For ophthalmic diagnostic testing, the difference between a routine report and a sub-speciality read is where private care earns its keep.
We’re honest about what private care can and can’t do. A private ophthalmic diagnostic testing appointment in London won’t change the underlying medicine. The guidelines, the consultants, and the equipment are largely the same as on the NHS. What it changes is speed, continuity, and the amount of time you get to talk the findings through. Everyone we route to is GMC-registered and works within CQC-regulated facilities.