The normal eye can focus light on the retina to create a sharp image. This condition is known as emmetropia.
Any state other than emmetropia is called ametropia, and results in a refractive error.
The nearsighted eye is too long and light is focused in front of the retina. This condition is called myopia
The farsighted eye is too short and light is focused behind the retina. This condition is called hyperopia.
Presbyopia is the loss of the eye’s ability to zoom in and see close objects. It occurs naturally as part of the ageing process and causes us to hold reading material further away than usual. Eventually, we need reading glasses to see near objects clearly.
Presbyopia makes us hold near objects further away, and use reading glasses to see clearly.
Monofocal Lens Implant:
A lens implanted inside the eye that has a single point of focus. Glasses would normally be required to see clearly at other distances.
Usually a monofocal lens allows clear vision in the far distance. Glasses are then needed for reading, using a computer, and certain other activities.
A lens implanted inside the eye that has more than one point of focus. In addition to good vision in the distance, a multifocal lens provides a greater ability to see close-up without glasses than a monofocal lens.
Available in either monofocal or multifocal varieties, a toric lens can correct astigmatism as well as myopia and hyperopia. A toric lens may be advisable for patients with pre-existing astigmatism that are undergoing lens implantation surgery.
A Piggyback (or Add-On) lens implant is a thin lens that can be inserted in front of a lens that was implanted at the initial time of cataract surgery. This may be helpful for patients that still need to use glasses for distance vision or for reading, and can provide better vision without glasses at these distances.
Retaining the eye’s natural lens. A Phakic Lens Implant is inserted in the eye without removing the eye’s natural lens, and can correct myopia, hyperopia and astigmatism.
An eye in which the natural lens has been replaced by a lens implant is called ‘Pseudophakic’.
An eye which has no lens, either natural or implanted, is called ‘Aphakic’.