Visual Fields Testing
What is visual fields testing?
Visual fields testing is a subjective measure of central and peripheral vision, or ‘side vision’. This is used by your Optometrist to diagnose, determine the severity of and monitor eye disease, most commonly glaucoma. It is also useful to investigate other head related symptoms such as recent onset headaches. And in some instances can aid in the detection of more serious health issues such as strokes and tumours. The most common visual field test uses a light spot that is repeatedly presented in different areas of your peripheral vision.
When do I need a visual field test?
A visual field test is normally performed if your Optometrist suspects you may have disease of the optic nerve. The most common cause of optic nerve disease is glaucoma although various conditions can cause damage to the nerve. Your Optometrist will also perform a visual field test if they suspect other diseases affecting the visual pathways of the brain behind the optic nerve, most commonly strokes and tumours.
Please Note: Visual fields are not routinely part of a sight test. They are generally carried out based on signs and symptoms and clinical need determined by your Optometrist during your sight test.
Why do I need repeat testing?
Visual field testing can help work out the severity of a disease. Typically, glaucoma is a disease of the optic nerve that gradually develops over many years. In order to help diagnose or monitor glaucoma, repeated visual field testing is essential to track progression and ensure accuracy. It can also help the clinician to determine if your treatment plan is working. Most commonly are your eye drops controlling your Glaucoma successfully. Visual fields will generally be conducted on a regular basis as part of your management plan for glaucoma.
Isn’t there something easier?
OCT imaging of the optic nerve and surrounding tissues is an objective test that can also detect glaucoma damage and progression. Changes on the optic nerve can often be detected years earlier than visual field testing alone. This information can help your Optometrist make treatment decisions along with other tests such as your eye pressure. However, at this time, OCT has not replaced the visual field test. We still need both types of testing, because there are times that the optic nerve changes before the visual field. Also there are times when changes to the visual field are observed before damage to the optic nerve is detected.
What if I am worried I have not performed the test correctly?
Visual fields testing can be a patient’s least favourite test. That ‘clicky test’ tends to require a sustained level of concentration over several minutes. Patients worry they have either ‘over clicked’ or ‘under clicked’ the flashes of light presented to them. The technology is quite sophisticated these days and will go back to give patients more than one go at each point if needed to improve accuracy. The best advice is to ‘just do as best you can’ as being relaxed will help your ability to perform this test. If required, your Optometrist can arrange a repeat visual fields test if your results are not accurate enough first time round.
NB: Your Optometrist will work with you to ensure results are as accurate as possible including repeat testing if required.
I have visual fields carried out at the hospital, do I still need this test with my Optometrist?
On the high street, visual field testing is carried out more in the initial detection of glaucoma. If glaucoma is suspected, your Optometrist will arrange a referral to your local eye hospital for further assessment. The eye clinic will then arrange ongoing visual field testing as part of your manage plan. Therefore repeat visual field testing with your Optometrist will usually not be required (unless requested by the hospital). If your Optometrist suspects another new condition they may still conduct visual field testing.
I have been asked by the DVLA to have a driving visual fields test
A driving visual fields test or ‘Estermann’ is a special visual fields test. It is the only visual field test that is carried out with both eyes together. It is basically designed to ensure safety when driving and that your vision is ‘wide enough’ to see potential hazards at the side of the road. Certain eye diseases such as glaucoma can restrict peripheral vision. As such the DVLA will often request a driving fields test. The DVLA letter will outline how to access this test if required.
Please Note: Private DVLA Estermann visual field testing can be carried out at Focus Medical Eye Centre but is chargeable.
For further information or questions regarding visual fields testing please do not hesitate to contact the team at Focus Medical Eye Centre on 01323 442062.