Good Hope, Heartlands, and Solihull Eye Clinics


David Kinshuck

What is a cataract?

Light enters the eye from the front, passes through a clear lens, and reaches the back of the eye so we can see. If the lens becomes cloudy like frosted glass, light cannot pass through, and you cannot see properly. 'Cataract' is the name of the 'cloudy' human lens.

large diagram of cataracts

See animation
top: a clear lens, no cataract. Light enters the eye directly.
bottom: a cloudy lens = a cataract. Light entering the eye is scattered.


animation of cataract position

Think of a camera, with a lens that bends the light so that the light 'focuses' onto the film at the back. If this lens becomes scratched or greasy, it cannot bend the light in the correct direction, and the light is scattered in all directions. You may notice blurred or misty sight, see double, or notice colours appear much duller than they did previously.



What you can do

A cataract will not damage your eye in any way.  It can be operated on safely at any time, thick or thin. A cataract may change the focusing in the eye, and you may need new spectacles now and again.
If you think you do, ask your optometrist (optician) or the doctor in the hospital eye clinic. But glasses themselves do not help you see better if you have a cataract.
Some cataracts get worse quickly, others slowly: most do get worse over months or years. If your sight gets worse very slowly, the cataract is only slowly becoming cloudier.
The thicker or cloudier the cataract becomes, the worse the sight.  A doctor cannot predict with certainty.



a good reading light makes reading easier

Large print is naturally much easier to read, and a magnifying glass may help  (see Coping with poor vision).

A good light may help, particularly an anglepoise light behind the shoulder.

Stronger glasses that mean you can bring books closer to your eye to make reading easier, and an optician (optometrist) can advise you. 






glare from car headlights in cataracts

glare from headlights is a common problem with early cataracts

You may notice great difficulty driving at night, when car headlights are shining into your eye. This may be so bad you have to stop driving at night, and at this stage, if you want to keep driving, you may need a cataract operation.





glare from cataracts

glare from sunlight...another common problems with early cataracts


You may notice difficulty seeing in sunlight. Dark glasses may help, or a hat with a large peak. Eventually you usually need an operation.








Causes of cataracts

  • Cataracts occur as people get older. They are much commoner if you smoke, whether cigarettes, cigars, or a pipe. They occur more often in diabetes, and they can run in families. Steroid tablets may help to cause cataracts if given at a high dose or for a long time. See details below. There are many other causes, including other types of eye disease and eye injury, and hypertension. Epidemiology
  • In the UK smoking contributes to 25% of cataracts, increasing the risk 2-4 times 17% in Denmark, IOVS 12. Some smokers may have not have developed cataracts otherwise, and in other people they may have become denser because of the smoking see, Beaver Dam 2008. Passive smoking will contribute significantly, and we know know that if someone only smokes outside, when they re-enter the house, the smoke breathed out contributes to cataracts in the other householders.
  • Diabetes similarly contributes to 25% of the UK's cataracts.
  • a poor diet contributes, see below
  • Statins contribute to a little cataracts, although the benefits usualy outweigh the risks.
  • Lask of vitamain D is related to cataract  OE 17   Vitamin D
  • cataract can be related to general health Eye 21

Does a cataract damage the eye, or your other eye?

A cataract does not usually damage your eye in any way. A cataract in one eye cannot lead to any damage in the other eye, and you cannot use the good eye too much and damage it. Similarly, sit close to the television if this helps you see it better: this will not damage your eyes. A cataract often develops in the other eye, but many people only get one in one eye.


Will your sight & the cataract get worse?

Many cataracts do get worse, especially if you are middle aged and have diabetes. Many people with diabetes do eventually need cataract surgery.


Does a diet help?

  • UK Department of Health advise a diet low in animal fat and salt, with five portions of vegetables or fruit a day, with 30 minutes exercise such as walking, and not smoking. In diabetes, diet, control of the blood sugar and  blood pressure are important to prevent other problems. A healthy diet postpones cataracts (AJO 2010: a poor diet & obesity increases risk by ~50%).
  • Recent research, also , also has shown that dietary factors such as high cholesterol and low levels of lutein and zeaxanthin (in vegetables and fruit) are found in cataract patients. This indicates that a healthy diet will help substantially to prevent cataracts.
  • There should be little added salt, and little saturated or trans fats (these are in animal fats such as red meat and dairy food, and include some 'hard' vegetable fats in many biscuits and cakes) and include 2 portions of oily fish such as sardine, tuna, or salmon a week. Lots of vitamins (as in vegetables and salads) will reduce the likelihood of cataracts Carotenoids, Vitamins C and E.



cataract...nuclear sclerosis    mature cataract...very dense with very poor vision.

Mature cataract...very dense with very poor vision. Such cataracts are uncommon in the UK. enlarge

Cataract...nuclear sclerosis. Cataract is slightly brown, and colours do not seem as bright to the patient  enlarge .





When do you need an operation?

An operation to remove the cataract is usually the only way to make improve your sight. But before you can decide, you need to know the pros and cons of an operation. A cataract operation is generally safe, and with a surgeon who is experienced in small incision cataract, the risk of a serious problem is about 1%.
So in a way you are the best person to decide: certainly, if you cannot do what you want to do, such as read, watch TV, or walk in the street, an operation is usually helpful (if your eye has no other conditions.) Many patients who have surgery are in their 80's. See animation and another

Poor contrast sensitivity (unable to see shades of colours), reduced sight in poor light and difficulty reading are visual symptoms caused by eye conditions, and may indicate surgery may help.


The Operation

cataract surgeryA small hole is made in the side of the eye and a probe is placed in the eye to cut and suck the cataract out.

See animation and another

lens implant after cataract surgery

A plastic lens is placed in the eye to replace the cataract. The lens focuses the light onto the retina, like the lens of a camera.



The operation isperformed as a day case. You go to the hospital in the morning, and go home later that day. You have a local anaesthetic injection or drops, wait for it to work, then have the operation which takes about 10-30 minutes. Sedation helps anxious patients.
A small cut is made and a small tube is inserted into the eye to suck the cataract out, and a plastic lens implant is put in its place. The plastic lens implant is placed in the 'capsule' of the cataract.

The only major discomfort can be the local anaesthetic injection. At home, you have drops to put in, and after the operation may have one to the hospital before seeing your optician for glasses. Normally after an operation, you see well. However, if there are other problems in your eye, such as a damaged retina (the film at the back of the eye), your sight will not be so good.

In diabetes the operation may make the retinopathy worse and laser may be needed. Often the ophthalmologist recommends laser or injecions before the operation to try and stabilise the retinopathy. (See page concerning your type of retinopathy.) See after your operation at Good Hope or BMEC.

What you see during operation Eye 16.







You will usually need glasses after cataract surgery. Sometimes you only need them for reading. Many people see well after surgery without glasses, but see that little bit better with them.



Glasses ..more details

The size of your eye is measured before your operation so your doctor can determine which implant to use. Normally

  • You need to have that eyes balance, that is have a similar lens prescription in the 2 eyes.
  • If you are short sighted you might still want to be short sighted after your will need to tell your doctor this. (This will allow you to read without glasses.)
  • Normally your doctor uses an implant that may enable you to see in the distance without glasses (this is equivalent to 0 dioptre [0d]). However, the measurements are not a 100% accurate, and most people do need glasses after surgery. Occasionally the measurements are 3d out, but this is very unusual indeed.
  • Before your surgery you may wear glasses with thick lenses in each eye. For example, these may have a +5d prescription in both eyes. Your doctor will usually suggest you are about 0d after your operation. But of course this means that after the first operation you will be 0d in one eye and +5d in the other...this means you will not be balanced. So then you have choice... to proceed with an operation in the second eye, to struggle not being balanced, or to wear a contact lens. (A contact lens can balance eyes with a 5 d difference, whereas glasses will often only balance your eyes is there is only 3d difference or less. This is called 'anisometropia'.)
  • If you wear glasses with a -5d prescription in both eyes for example, and only have a cataract in one eye, and only want one operation, you need to tell your doctor. He will try and use an implant that still allows the two eyes to balance..., for example, he may aim for -3d in the eye with the operation, -5d in the other. You need to discuss this before surgery.
  • Occasionally there may be unusual situations. For example, a person with macular degeneration may wear +5d glasses in both eyes. These magnify images a little. After surgery they may be 0d in both eyes...but images may be smaller, and the patient may be unhappy. It is this and other problems the doctor will try and help avoid.
  • If your prescription is 0d for distance after your operation, you will still need +2.50d reading glasses. (After cataract surgery your eyes cannot simultaneously focus on near and distant objects...only people <45y who have no cataracts or surgery can do this.)
  • This is explained in more detail here.

Toric lenses

These correct the astigmatism. Astigmatism is the optical effect of a 'rugby ball' or 'egg' shaped eye (the normal eye is round or football shaped). It is the corneal shape that has the different shapes. Astigmatism is common and is usually mild and corrected with spectacles.

Toric lens implants will correct the astigmatism. These lenses are slightly rugby ball or egg shaped in the opposite way to the cornea itself. Toric lenses are not normally available on the NHS, but certainly may help patients with significant astigmatism. This is especially so if the patient has not had good sight with contact lenses or spectacles before the cataract developed.  
At this stage they are too complicated to use for patients with mild astigmatism, and they have to be specially ordered. However,  toric lenses for astigmatism will make most patients spectacle independent, versus 45% with none toric ordinary lens implants.

Nevertheless. with mild astigmatism and ordinary lens implants, wearing spectacles after the operation will provide excellent sight for most patients.


Multifocal implants and monovision for those who do not wish to wear spectacles

We need 3 focus points

  • Light coming from a distance, such as a house across the road, has a different focus from light coming from computer screen or piano music, which is in turn different from light coming from much closer as reading a book. See The young eye has a lens that changes shape to focus on all three distances, but the older eye or the eye with a plastic lens implant after cataract surgery cannot do this. diagram    text etc
  • To enable a person to see all 3 distances , spectacles are needed, such as reading glasses , bifocals, or varifocals. Varifocals have the advantage that they don’t have to be taken off and on all the times, but some people don’t want spectacles or can’t get used to the varifocal lens.
  • multifocals are not suitbabl for people with 'neuroticism as the dominant personality trait'  Eye20 .

Multifocal lenses

  • To cope with this, some surgeons recommend multifocal lenses. But a multifocal lens splits the light into 3 parts, so any object in focused will only be a third the quality compared to the focus of a single focus lens. Many surgeons (including myself) do not recommend these. CER 18


  • If a patient really does not want spectacles, some patients can accept monovision. That is, one eye is focused for near vision, and the other for distance. In such a patient generally no spectacles would be needed. But if the patient wants to do a lot of reading or driving, they could obtain spectacles that would allow both eyes to be in focus for near and distance. Most of the time patients with monovision would not need to wear their spectacle when no intense eye use is needed. However, not all patients can tolerate such 'monovision' comfortably.    Monovision professional   Patient

Bilateral same day cataract surgery

This is generally not advised unless a general anaesthetic is needed or there are special circumstances. There is an infection/complication risk.


Risks and refractive outcome

There are risks with cataract surgery. Approximately 1% of patients do develop serious complications, and this risk can be higher if your cataract is thick, for example. 

  • Professionals see risks here.
  • Macular oedema: particularly if there is diabetes and especially if there is diabetic retinopathy .
  • Other risks include: corneal decompensation (especially if Fuchs is present), dropped nucleus, iris  problems, lens position problems, etc.

Refraction result

  • 50% of eyes will have a refractive error of less than or equal to 0.5 d
  • 85% within 1 d
  • there may be haloes around lights whatever the lens used
  • more haloes with multifocal lenses
  • multifocals: increase focal range but with reduced contrast

Glare and other optical problems post op

  • Rarely patients notice glare from lights. Occasionally these may be due to an aspheric lens. The problem may be confirmed with wavefront analysis.
  • there may a type of peripheral ring scotoma (section of vision missing), an optical problem from edge of the lens implant.
  • dysphotopsia  AJO 19


Flomax (tamulosin)

This drug may cause a  floppy iris during your cataract operation. Please tell your ophthalmologist if you have ever had this drug. If your GP wants to give you the drug, and you are about to have cataract surgery, it is important to wait until after the cataract surgery before starting it. ADRA1A  


Fuchs endothelial dystrophy

This condition is explained here. Cataract surgery is more risky in this  condition, as Fuchs dystrophy and the surgery can combine to damage the cornea permanently. New research suggests that surgery with care, the latest techniques, for patiens with a milder dystrophy surgery is generally safe without a corneal transplant.


Trabeculectomy & cataract surgery

previous trabeculectomy: the valve may block with cataract surgery


Cataract surgery might affect previous glaucoma surgery. Trabeculectomy surgery creates a valve that lets aqueous fluid seep out of the eye. This valve may block if anti-scarring drugs are not given at time of cataract surgery. Animation

If you have had a trabeculectomy in the eye needing cataract surgery, you have a choice.

  1. the cataract surgery can be combined with an anti-scarring drug such as 5FU  10mg/0.04mls subconj (this will usually have to be given by a glaucoma consultant).
  2. you can have the cataract surgery without the drug, but there is a small chance the valve created in the trabeculectomy operation will block. If it does block, the pressure in the eye will go up again and glaucoma drops will be needed long term (Sharma).

At Good Hope we recommend the first option, particularly if the cataract operation is likely to be complicated (e.g. if there is a small pupil, if the glaucoma is advanced, if there has been uveitis etc).


Cataract surgery and diabetes/ diabetic retinopathy

Patient with uncontrolled diabetes or diabetic retinopathy (unless the retinopathy is completely stable) generally need  Yellox drops twice daily starting 5 days before surgery, and continuing after surgery for 2 weeks. An increase in macular oedema is common Eye 17.


Cataract surgery and wet armd

Wet armd may be made more active by cataract surgery. Some doctors recommend delaying cataract surgery, but this author suggests continuing regular anti-VEGF injections before and after the surgery should be sufficient. AJO 18



Drugs that contribute to cataracts

Two common types of drugs contribute to cataracts

  • Steroids..tablets, facial creams especially if used around the eye, steroid eye drops. These are in common use...they are very helpful in preventing more serious problems from many inflammatory conditions. Nevertheless they do contribute to cataracts. If you are using steroid medication do not stop the drug without discussing the situation with your doctor.
  • Statins (BMJ 2010) contribute to cataracts. For every 100 cases of heart disease prevented, 66 cataracts are produced. Nevertheless statins can be very helpful preventing many conditions, and have many other benefits. They may even prevent age-related macular degeneration.

Diseases that contribute to cataracts

  • Muscle weakness: myotonic dystrophy  Eye 18

Small print

Patients wanting to know more details may wish to read this page for professionals. Or even this page ps technical