A cataract is not, as many people believe, a milky film that grows over your eye. It is the frosting or clouding of the curved lens inside the eye.
The most common cause is ageing. According to some estimates, by the age of 65 nearly half the population develop the earliest form of cataracts. At 70, almost everyone has some degree of cataract formation. Other causes include some eye injuries, chronic diseases such as diabetes and some other eye diseases. A few people develop cataracts from as young as 40.
Cataracts can take anything from a few months to many years to develop. Sometimes the process stops in the early stages and vision is not seriously affected. In other cases, the cataract continues to develop and interferes with vision. Cataracts usually develop in both eyes but they may develop at different rates, so vision in one eye is often significantly better than in the other.
The key symptom is blurred vision that worsens over a period of months or years. Some people notice that things seem dim with one eye and brighter with the other, while printed images may have a ghosted outline. Colours become less distinct and many patients are bothered by glare — for example, from the sun or oncoming headlights.
Even if other factors, such as glaucoma or age-related macular degeneration, are contributing to sight problems, the removal of the cataract and replacement of the lens should ensure improved vision.
Cataracts are usually diagnosed during a standard eye examination by a qualified optometrist. If you think that your eyes are being affected by them, go to your optician and ask an optometrist to check. The optometrist can also look for other common eye conditions, such as age-related macular degeneration or diseases that affect the optic nerve (glaucoma).
If you have cataracts, the optometrist will monitor them and advise if and when you might need treatment — people often live with them for many years without needing an operation. There is no set level of dimming of vision before an operation is recommended but if the condition is badly affecting your lifestyle or you can no longer meet the legal sight requirements for driving, you should seek help.
"Even the night after having the first eye treated, I could see far better. The next day, it was as if the windows had been cleaned because my vision was much brighter."
Below is an animation which shows the cataract operation.
The procedure normally takes place under local anaesthetic that numbs the eye, using eye drops and an anaesthetic infusion around the eye. The procedure typically takes about 15 minutes. It is one of the most common operations in the UK and it is normal to operate on each eye on separate occasions. You will not see what is happening but you will be aware of a bright light and may see a kaleidoscope of colours. You should not feel any discomfort.
During the operation, a micro-incision, approximately 2mm in size, is made at the edge of the cornea. A tiny probe is inserted into the eye and the existing lens is gently broken down by ultrasound and removed. The process is called phacoemulsification.
A new lens implant is inserted to replace the natural lens that has been removed. The strength of the new lens is chosen before surgery, after your eye has been measured by a laser or ultrasound scan. The new lens is placed where your natural lens used to be. As the incision is so small, stitches are rarely required.
The most common type of lens used is called a monofocal lens implant. It will allow you to see well in the far distance, probably without glasses, but you will need glasses to read for near and possibly also in the intermediate distance.
There are newer lenses available that are approved by NICE, but are not commonly used in the NHS. These are called multifocal or accommodating lenses. These allow your vision to be corrected in the distance, and depending on the type of lens used, also your intermediate and near vision. Mr Malhotra will explain whether this type of lens implant is suitable for you before surgery.
Before signing the consent form for surgery, it is important that you understand the procedure and what the risks and benefits are to you. Please feel free to ask Mr Malhotra any questions that you may have.
The benefits of surgery include greater clarity of vision and improved colour vision. The potential risks associated with cataract surgery are rare but include blindness, haemorrhage, infection, glaucoma, retinal detachment, capsule tear and vitreous displacement, wound dehiscence and iris prolapse, cystoid macular oedema, deterioration in diabetic retinopathy, intraocular lens implant dislocation and lens implant power miscalculation.
Some patients may require further or additional surgery following cataract surgery. You may wish to discuss this further with Mr Malhotra if you do not understand these medical terms.
All operations and anaesthetics carry some risk. Using modern methods, cataract surgery is extremely safe and, in the vast majority of cases, highly successful in improving vision. The time taken for this improvement to take place can vary between patients and may not happen immediately after surgery.
All procedures begin with a consultation. For full information about what to do before and after surgery, see Patient information. You can also read this Patient case study to find out what the experience is like.
For cataract patients keen to reduce their dependence on glasses for near and long distance vision, Mr Malhotra will often recommend the ReSTOR lens.
Studies show that 80 per cent of patients do not require spectacles for daily activities after receiving implants. A ReSTOR lens should therefore allow you to drive legally and read in good light, with both eyes and without the need for glasses.
Mr Malhotra has been an accredited ReSTOR lens implanter since March 2005. "I have continued to be impressed by the safety and quality of this lens implant since the first patient I offered it to was able to see 6/6 (20/20) and read N5 — less than half the size of newsprint — at 40 cm without glasses, within the first week following surgery," he says. "I couldn't have hoped for better."
A European study reported by the journal Ophthalmology in April 2006 reported on 127 patients with a mean average age of 68.4, all of whom were given the ReSTOR lens. Of these, 119 had ReSTOR lenses in both eyes.
Six months after surgery, mean binocular (using both eyes simultaneously) distance vision without glasses was 6/6 — a rating more commonly known as 20/20, or perfect vision. Binocular near vision without glasses at 33 cm was 6/12 or better, meaning that people were able to read newsprint, for 97.5 per cent of patients. The rating rose to almost 6/6 — less than half the size of newsprint — or better for 66.9 percent of patients.
Similarly, when tested at best distance, 97.5 per cent of patients achieved binocular near vision without glasses of 6/12 (newsprint) or better and 71.2 percent achieved 6/6 or better.
Distance vision without glasses was achieved by 88 per cent and near vision without glasses was achieved by 84.6 per cent of patients.
But no lens is perfect for everyone. Symptoms of glare were reported as severe by 8.5 per cent of patients and halos were seen by 4.2 per cent of patients.
After the first ReSTOR was implanted, 92 per cent of patients said they would have the same lens implanted again. After the second implant, that number rose to 95.7 per cent.
Visit the ReSTOR web site