A cataract is the clouding of the natural lens inside the eye, behind the iris (the coloured part of the eye). The lens is one part of the eye that focuses your vision onto the back of the eye, the retina.




Cataracts gradually develop with age and present with a range of symptoms including:


  • Cloudiness or mistiness of vision
  • Loss of vibrancy of colour
  • Glare especially with bright lights such as from oncoming car headlights at night
  • Frequent changing of glasses prescriptions


While cataracts usually develop with age, other causes include inflammation, previous trauma, steroid use and diabetes.


The only way to treat cataracts is through surgery. Cataract surgery is the most commonly performed surgical procedure in the UK, with over 300,000 surgeries performed each year. It is routinely performed as a day case under local anaesthesia and takes around 30 minutes. You’re usually free to go home the same day with eye drops to reduce inflammation and infection for several weeks. The cataract is gently broken up (phacoemulsification) and replaced with a plastic lens implant to focus your vison. A range of different lens choices is now available and can be inserted based on your glasses prescription and personal preference.

Standard Lens Implant

Monofocal lens: This is the standard lens used in the NHS. These aim to correct distance vision without glasses but glasses will still be needed for reading.


Some patients who have always been short sighted may choose a lens power to achieve comfortable reading without glasses (usually -2.0 to -2.5 dioptres to achieve reading vision at 40-50 cm) but will need glasses for distance.


Blended Vision: Some patients also choose what is referred to as monovision blended vision. This is when the dominant eye is corrected for distance and the non-dominant eye is corrected for reading/intermediate vision to achieve glasses independence for most activities.

Premium Lens Implant

Toric lens: These aim to correct astigmatism. Astigmatism is when the surface of the eye is not completely spherical and is commonly referred to the eye being shaped more like a rugby ball than a football. This can affect the quality of vision and a toric lens implant can aim to reduce this.


Trifocal lens: This is similar to a varifocal lens found in glasses and aims to provide distance, intermediate and near vision without glasses.


Extended depth of focus (EDOF) lens: These are similar to trifocal lenses in that they aim to provide distance, intermediate and near vision without glasses.


While some studies suggest that EDOF lenses may not be as good for near vision activities compared to trifocal lenses, other studies also suggest that EDOF lenses may have less risk of halo or glare than trifocal lenses (more so at night).


However, studies have generally found both trifocal and EDOF lenses are well tolerated, providing good levels of vision at all distances with a high percentage of spectacle independence and little impact of visual symptoms on daily functioning.


Toric Trifocal/EDOF lens: These lenses aim to achieve to correct astigmatism as well as to provide distance, intermediate and near vision without glasses.


Secondary lens enhancement: If you have had previous cataract surgery with a standard monofocal lens implant, a secondary lens may be placed in front on this lens to correct residual refractive error or astigmatism. A secondary trifocal lens may also be placed to provide distance, intermediate and near vision without glasses.


To discuss cataract surgery and your vision needs in more detail, please feel free to arrange a consultation with Dr Lee by clicking here.