In simple cataract surgery a single vision (mono-focal) intraocular lens (IOL) is implanted into the eye at the time of surgery. A mono-focal IOL is an intraocular lens with a fixed focus for one distance.

Like an eye’s natural lens, an intraocular lens focuses light that comes into your eye through the cornea and pupil onto the retina, the sensitive tissue at the back of the eye that relays images through the optic nerve to the brain.

Mon-focal IOL is normally set for distance vision. If a cataract patient does not have significant astigmatism (there is no uneven curve in the front of eye i.e. the front of eye is spherical like a football rather than shaped like a rugby ball) then after implantation of a mono-focal intraocular lens most patients can achieve good spectacle free distance vision if they do not have any other significant eye problem. They will need glasses for reading or close work.

Private Eye Surgery Consultants during simple cataract surgery routinely use premium aspheric mono-focal intraocular lens.

Why is this important?

Traditional mono-focal intraocular lenses have a spherical optical design, meaning the front surface is uniformly curved from the centre of the lens to its periphery. This lens is easy to manufacture, this design does not mimic the shape of the natural lens inside the eye, which varies in curvature from centre to periphery. The natural lens is aspheric in shape.

A spherical intraocular lens can induce minor optical imperfections which can affect quality of vision, particularly in low-light conditions such as driving at night. Premium aspheric IOLs, on the other hand, match the shape of the eye’s natural lens and they provide sharper vision as compared with spherical intraocular lenses — especially in low light conditions and for people with large pupils. 

Private Eye Surgery consultants offer their private patients who have significant astigmatism advanced cataract surgery with toric intraocular lenses or limbal relaxing incisions.

In astigmatism the front of eye is not spherical like a football rather than shaped like a rugby ball. This results in distorted images, as light rays are prevented from meeting at a common focus.

If patients with significant astigmatism undergo simple cataract surgery with mono-focal intraocular lenses then they will need spectacles not only for reading and near work but also for seeing clearly in distance. These patients with significant astigmatism need either correction of their astigmatism during surgery either with special cuts to front of eye (limbal relaxing incisions) or use of special intraocular lenses which correct astigmatism (toric intraocular lenses) to allow them to get good spectacle free distance vision and more spectacle independence for distance. They will still need glasses for reading and near work.

In advanced cataract surgery special scans of the front of the eye will be done before the surgery to measure the difference in the curvature of the eye in different axis (astigmatism). Depending on the results of the scans and measurements of the front of the eye a decision will be made after discussion with the patient to either correct the astigmatism with special cuts to the front of the eye (limbal relaxing incisions) or to use an appropriate toric intraocular lens which can correct the measured difference in curvature of the front of the eye.

Refractive cataract surgery has the potential to give cataract patients spectacle independence after cataract surgery. Refractive cataract surgery can allow most patients to see clearly without glasses or contact lenses both for distance and near.

Private Eye Surgery consultants offer refractive cataract surgery to their patients. In this procedure the ageing natural lens of the eye is removed and is replaced with a special premium intraocular lens implant (IOL) which in most patients allows good spectacle free distance and near vision.

Following are the different types of premium intraocular lenses available which can be used for Refractive Cataract Surgery. These are same as used in Refractive Clear Lens Replacement.

• Multifocal Intraocular lenses
• Extended Depth of Focus Intraocular Lenses
• Trifocal Intraocular Lenses
• Toric Multifocal Intraocular lenses
• Toric Extended Depth of Focus Intraocular Lenses

Cataract patients desirous of having refractive cataract surgery have a detailed pre-operative examination. Depending upon their life style/visual requirements and results of their eye measurements/scans an appropriate premium intraocular lens is selected by the surgeon in consultation with the patient for this procedure.