The NHS sight test was formulated some sixty years ago and has changed but little over time since its inception in the 1940s. Our Extended Eye Examination can now test for a much wider range of conditions than was ever possible before.
We have a number of leading instruments and topographers to help us find out how your eyes are performing and whether there are any issues with the health of the eyes or indeed, any general health points that would be helpful to your doctor.
The extended examination is normally carried out straight after the normal examination and involves performing additional tests as listed below. This takes around an extra 20-30 minutes or, if you are short of time, you can book these additional tests for another day. Usually the tests are reviewed later in the day and we will contact you with the results.
The extended eye examination is carried out by our Humphrey's visual field machine. This instrument records the field or width of vision and if there are any gaps in the field. Abnormal blind spots are characteristic of certain diseases such as glaucoma, or indeed strokes.
The test works by shining a tiny spot of light in various positions in your peripheral vision. You are asked to indicate when you have seen the spot of light by clicking a button. The intensity of the light is varied, so that the analyser can work out the exact amount of light needed for you to see it in every point in your visual field. This is called the Light Threshold. This test is only done when necessary as it is quite tiring for you. The computer compares your results against 10,000 'normal' patients in the same age group to see how much variance there is.
The corneal topographer measures the shape of the front surface of the eye (the cornea) and is able to illustrate any deviations in shape that could affect the quality of vision or any instabilities of the surface. The topographer is used in the design of Ortho-K lenses and also complex and multi-focal contact lenses.
Part of the standard test is to examine your retinas - the light sensitive area at the back of the eyes. As part of the Extended Eye Examination we provide advanced digital imaging using our optomap system. Many Retinal cameras photograph 45 degrees of the retina and take close ups of the nerve and macula. The Optomap does not normally require dilation but uses lasers to see around 200 degrees of your retina. It allows us to see almost to the retina's edges and there is a greater chance of picking up peripheral problems hidden to the normal examination. It also gives us a permanent record of what the back of your eye looks like, so we can make comparisons in the future and monitor progression of any disease.
The Extended Eye Examination also includes an OCT scan. This is similar to an MRI or CAT scan for the eyes. OCT can image in 3D, allowing your practitioner to see, sometimes for the first time, problems within your eye that could not be easily detected before. The test is very simple, taking just a few seconds, it is comfortable and completely non contact.
The OCT has a major part to play in diagnosis of age related central vision conditions (AMD) and in assessing the presence of glaucoma and diabetes. The images that the OCT produces are fine detailed cross sections of the living retina, allowing the interpretation of changes that would previously have been inaccessible.
We will always recommend an extended test if we need to further investigate specific signs or symptoms found during the normal eye examination, such as flashing lights or floaters, high intraocular pressures, or abnormal lesions shown on the retinal photographs. Often the tests are useful for screening purposes when there is a family history of potentially hereditary diseases such as glaucoma, age-related macular degeneration, or loss of vision in elderly family members.
We recommend regular screening and this thorough examination (at least every two years). However, it does take more time and is more expensive. Your regular Eye Examination is essential. The Extended Eye Examination might be essential but can also be considered an optional extra - it's up to you. Your Optometrist will recommend which of the extra tests are particularly appropriate for your needs, especially if a report is to be made for an Ophthalmologist's opinion.
Many of our clients place a great value on preserving their eyesight and like to have the extended eye examination rather than the standard test because of the greater peace of mind it gives them.
Please note that additional tests including Repeat fields and Aviation Pilots Licence (CAA, JAR Class 1 & Class 2) tests are costed separately. We also perform DVLA tests when requested by the DVLA.
To see the cost of the Extended Eye Examination, please see our Pricing Page.
Please contact us if you have any questions about any of the tests listed above.