The human eyeball measures an average of 24mm in size. Although small, it is an incredibly intricate organ. Light enters the eye through the front window (or cornea) of the eye. This light is then focused using the lens onto the retina. The retina is the light-sensitive tissue at the back of the eye that converts the light into an image signal for the brain. The lens of the eye is essential as it transmits light but also focuses it into a clear image onto the retina.
Patients with cataract will typically complain that their vision is not as good as it used to be. Patients may have difficulty reading fine print or they may have difficulty with glare, particularly when driving at night. Some people also find that reading becomes more tiring, and they have to take more frequent breaks. These symptoms usually develop slowly over months, but some types of cataracts really do develop much more quickly. The symptoms typically take patients to their optician who then diagnose them with cataract and refer them to see an eye surgeon.
Cataract is incredibly common. Cataract is the most common cause of reversible visual loss in the world. Cataract surgery is the most commonly performed operation worldwide. It has a fantastic success rate and can absolutely transform patients’ lives.
In the early stages, cataract may not cause any symptoms. Most people aged 40 or older will have a mild degree of cataract that does not require any concern at all. As cataracts progress, it may cause a change in the glasses or contact lens prescription. Regular eye tests with the optician can help keep up-to-date with these changes and ensure that patients can see very well with glasses or contact lenses. As time progresses and the cataract becomes more dense, there comes a time where glasses or contact lenses cannot correct the vision any further and this is the point at which cataract surgery should be considered.
Many studies have been done to see whether anything can prevent the development of cataract. A large study in America called the Age-related Eye Disease Study (AREDS) recruited almost 4,000 patients to try and see whether taking vitamin and mineral supplements can reduce the development of cataract. Sadly, this study did not show any benefit in taking any vitamin or mineral supplements for the prevention of cataract.
Nevertheless, there is no doubt that there are certain things that can lead to early cataract development. This includes smoking and I always advise that patients try to cut down on their smoking due to its negative health effects both on cataract as well as other eye diseases such as macular degeneration and other medical illnesses. Another thing that can bring on cataract sooner is medical conditions such as diabetes. This is another reason why good sugar control is important in diabetes.
+ What causes cataract?
By far the most common reason for cataract development is simply getting older. Cataract can develop in babies and children but this is very rare. Most people will develop cataract if they live long enough and cataract surgery can be done at any age to help improve patients’ quality of life. Nevertheless, there are other reasons why some people may develop a cataract earlier than would be expected:
+ When should I stop driving due to cataract?
In the UK, the DVLA have criteria for fitness to drive from a vision point of view. In order to be able to drive, people need to be able to read a car number plate from 20 metres with both eyes open and wearing the correct glasses. People also need to have good peripheral vision. If you are concerned that your cataract has affected your fitness to drive, it is best to seek advice from an optician who will be able to guide you further. If you have never been told that you have a problem with your peripheral vision, then you can measure out 20 metres and see if you are able to read a number plate clearly with both eyes open.
+ What should I expect during my appointment?
During your appointment I will take a full medical history so that I understand the symptoms you are experiencing with your vision. I will also ask questions about any previous eye procedures that you may have had and any medical conditions that you have together with any related medication that you take. I will then perform a full I examination by testing your vision and then use eye drops to dilate the pupil so that I check the front and the back of the eyes. This is important to allow me to assess the cataract as well as any other problems within the eye that can be leading to reduced vision.
If I do find that the problem is cataract, and you are keen to proceed with cataract surgery, I will endeavour to perform other tests on the same day to save you having to come back for a separate pre-operative assessment visit. These tests will include biometry to perform precise measurements of the eye. The nurses may also do some tests on the day to check your general health and well-being. In total it is a good idea to allow up to two hours for the appointment to save yourself having to rush.
+ Can I drive to my appointment?
As your pupils will be dilated with eye drops for the examination, you will not be able to drive for four hours after the drops go in. For this reason, some patients prefer to have someone drive them to the appointment and others choose to attend by minicab or public transport. Some patients are happy waiting around and doing some shopping or having a bite to eat after their appointment and that can be a very good way of enjoying the four hours until the effects of the drops wear off.
+ What should I bring to my appointment?
It’s a very good idea to bring any optician referral letters or recent eye tests to your appointment. As well as this it is very useful to have a list of your up-to-date medications as well as any distance and reading glasses that you are currently wearing. If you have a friend or relative who can attend with you, that is always a comforting support and they’re always welcome to be in the consultation with you.
+ What is preoperative assessment?
A preoperative assessment is a check of your general health to ensure that you are in the best possible shape for surgery. This includes things like a blood pressure check as well as a blood sugar check, especially if you are diabetic. The assessment will need to be more thorough if you have significant medical conditions or if you will need general anaesthetic for your cataract surgery.
+ Why do blood pressure and diabetes matter?
High blood pressure and poorly controlled diabetes can be very harmful to the eyes and I am always very keen to detect these so that they can be managed to protect the health of the eye. In the context of cataract, poorly controlled diabetes can certainly cause the development of an early cataract. In the context of cataract surgery, the procedure should be deferred until the blood pressure and the diabetes are well controlled as high blood pressure and high sugar can lead to complications during and after surgery.
+ Will I need an OCT scan?
Optical coherence tomography (OCT) is a high-definition scan of the retina and optic nerves. This is fast becoming the standard of care in cataract assessment to ensure there is no other reason for any reduction in vision. This can be performed on the day and gives us the reassurance of knowing that the retina has been assessed fully before embarking on cataract surgery.
+ Does cataract change my glasses prescription?
As cataract develops, the substance of the lens of the eye becomes more dense. As a result, the refractive power of the lens increases and this leads to patients becoming more short sighted. It therefore makes perfect sense that a patient’s glasses prescription will change as a cataract develops. As time goes on and the cataract becomes more dense, further changes in glasses simply cannot compensate for the changes in the lens of the eye and cataract surgery will be needed.
+ I’m in a wheelchair. Can my eye still be assessed?
The equipment that we have to assess eyes is wheelchair-friendly. The slit-lamp microscope can accommodate a wheelchair, as can the OCT retina scan. In the rare cases where a scan cannot be done on the day because of difficulty with wheelchair access, this may need to be arranged for another site on a different day to ensure a thorough assessment of the eyes.
+ Are you able to give me new glasses?
The best people to assess and prescribe glasses are opticians. These are otherwise known as optometrists. They are highly trained in assessing the prescription in people’s eyes and prescribing and dispensing glasses for this. Eye surgeons [otherwise known as ophthalmic surgeons or ophthalmologists] work very closely alongside optometrists to help patients with their vision. In clinic, I am able to perform refraction to establish a patient’s refractive error. However, in general, I recommend patients see their optician for glasses and see me when they need surgery to improve their vision.
Cataract is a common and a very treatable reason for reduced vision. A thorough eye examination is essential for all patients with cataract, especially when surgery is being considered to improve the vision. Due to great advances in technology, cataract surgery has a very high success rate.
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