Visual acuity test (1): best clinics abroad

A visual acuity test measures how clearly you can recognise letters, symbols or pictures at a specified distance. Each eye is usually assessed separately, with the chart and testing conditions documented. Distance vision and near vision are different measurements, and results may be checked with or without glasses or contact lenses. The test helps identify reduced clarity of vision and provides a baseline for comparison, but it is only one part of an eye assessment.

When arranging testing abroad, describe any visual symptoms and bring your current glasses, contact-lens details, prescriptions and previous eye reports. Clarify whether the booking covers chart testing alone, refraction to assess lens correction, or a fuller examination by an eye specialist. Ask how the results will be recorded and explained, and whether additional tests are included in the quotation. Sudden loss of vision needs immediate medical assessment and should not wait for a planned overseas appointment.

What happens during chart testing

You read progressively smaller letters or identify symbols while one eye is covered, then repeat with the other eye. The examiner chooses a suitable chart and testing distance. If reading letters is difficult, ask about symbol or matching charts and communication support. Describe blur, distortion or other symptoms even if you can read a line clearly.

Distance, near vision and score notation

Distance charts are often calibrated for six metres, or twenty feet, but the required distance depends on the chart and equipment. Snellen results use fractions such as 6/6 or 20/20. A logMAR chart uses a different numerical scale. Ask which system was used before comparing numbers from different reports.

Near vision is tested separately with a reading card or other suitable target. A good distance score does not automatically describe reading vision. For useful comparisons, the record should identify the eye, chart, testing distance and correction worn.

Glasses, contact lenses and preparation

Bring your current distance and reading glasses and contact-lens information. The clinician may measure unaided vision and vision with correction. Best-corrected acuity refers to performance with the best lens correction established during refraction; wearing your existing glasses is not necessarily the same assessment.

Chart reading itself is non-invasive. Ask whether the wider appointment includes pupil-dilating drops or other examinations, as these can affect your plans afterwards. Tell the team about previous eye surgery, existing conditions and the onset of new symptoms.

What the result can and cannot tell you

Reduced acuity may relate to a need for different glasses or an eye condition requiring further assessment. Chart testing does not determine the cause by itself. It also does not assess every aspect of vision or replace examination of the eye's structures. A comprehensive assessment may include eye pressure, visual fields and examination of the retina and optic nerve.

Planning an assessment abroad

Ask an ophthalmology specialist which examination fits your symptoms and previous findings. Request an itemised quotation for acuity testing, refraction, consultation and any additional tests. Arrange a written result, report language or translation, and a plan for follow-up at home. Seek immediate medical care for sudden vision loss or sudden severe eye pain.

Frequently asked questions

Is this a complete eye examination?

No. Visual acuity measures clarity under the test conditions. Other examinations assess different aspects of eye health.

Does a normal score exclude eye cancer?

No. A normal chart score is not a cancer-exclusion test. Concerns require appropriate specialist examination and, when indicated, imaging.

Will the test give me a glasses prescription?

Not by itself. Ask whether refraction and a prescription assessment are included.

How should I compare old and new scores?

Check the notation, eye tested, distance and correction. Ask the clinician to explain whether the measurements are comparable.