Monofocal lenses are the most common type of intraocular lens (IOL) for cataract patients. When light enters the eye through a monofocal lens, it is bent to a single focus point on the retina.
Light cannot be focused from both distant and near objects at the same time with this type of lens. It means that a monofocal lens can correct vision at one distance, providing good vision for either near, or far distance.
Most patients choosing a monofocal lens want to have good distance vision, allowing to perform activities such as driving and watching TV. They usually need to use glasses to help with near vision tasks, such as reading, cooking and working on the computer.
While most surgeons implant monofocal IOLs with distant focus to correct far vision, it is also possible to choose a monofocal lens with near correction to enable good vision up close. For all other distances, the patient needs to wear glasses.
The decision about whether distant or near vision should be corrected with the IOL depends on the patient's lifestyle and visual needs. The decision should be made in agreement with the surgeon after a close consultation with the patient.
Another option are bifocal lenses, which have two focal points. Read more about bifocal lenses, and if this option is more suitable for you.
Standard types of monofocal IOLs have a spherical optic, which is equally rounded on both sides. This type of lens is normally paid for by your health insurance.
However, the natural crystalline lens of the eye has a slightly aspherical (not completely round) shape at the front, and is not equally curved on both sides. This shape enables it to precisely focus light rays entering the eye onto one point on the retina. The result is a clear, crisp image.
Modern monofocal IOLs are available with an aspherical optic very similar to the original shape of the crystalline lens.
The special design of aspheric IOLs enable an enhanced image quality.
Additionally, if you have an irregularly shaped cornea, a monofocal lens in a toric version can improve your quality of vision considerably. Consult with your ophthalmologist to find which type of monofocal IOL is right for you.