Eye Test: The Guide

Here at our clinic in London, we are performing different tests to examine your eye condition. Each eye test helps to find the best treatment option for you and to get a satisfactory outcome in healing your eye disease.

Visual acuity

This eye test is the measurement of how your eyes can pick up small details. This measures how clearly objects or letters of different sizes can be seen by your eyes. This is often given as a decimal. For example, 6/6 is the commonly recognised version that means a person can read a letter at 6 metres that was designed to be read at 6 feet. If a person scores a vision of 6/5, their vision is better than average (they can read at 6 metres what most people would read at 5 metres) and if the vision is 6/18, it is worse than expected.

Pupil dilation

The pupil is the curtain of your eyes. It controls how much light enters the eye. Your doctor may need to perform a detailed examination of your retina, especially if there are symptoms of blurred vision or distortion. Then the pupil needs to be made large to allow a sufficient view of the retina. This process will also affect the muscle that controls focusing on objects nearby such as reading. Your vision will be blurred for about 4 hours after the drops are instilled. You will also find bright lights difficult and it is useful to bring sunglasses with you for your journey home.

Visual field test

This is a machine that tests how well a person can see around them. Each eye is tested separately. The patient needs to look into a bowl-shaped area and a small light stimulus is presented to them in different locations. This eye test does take some concentration and you will need to know what your spectacle prescription is for the best results. Most people have abnormalities on the first test as they are learning to do the test. If an abnormality is found, the test may be repeated or further investigations may be required.

Fluorescein angiogram

This is an investigation that involves the injection of a yellow dye into the veins of the arm. This then circulates in the body and is used to identify abnormalities of the retinal blood vessels. A special camera is used to take photographs of the retina. The whole eye test can take up to 20 minutes. Your doctor will apply eye drops that will dilate the pupil. This will make your vision blurred for about 4 hours.

Optical coherence tomography (OCT) scan

This is a machine that uses a highly specialised laser to measure the thickness of the retina. This laser is safe to use in the eye and will enable your doctor to identify microscopic abnormalities of the retina. This will assist in the accurate and rapid diagnosis of conditions such as wet age-related macular degeneration and in monitoring the progression of diseases such as glaucoma. The scan takes about 5-10 seconds per eye. Your doctor will apply eye drops that will dilate the pupil. This will make your vision blurred for about 4 hours.