cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light. Early in the development of age-related cataract the power of the lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colours. Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated. The condition usually affects both eyes, but almost always one eye is affected earlier than the other.


There are 3 main types of cataracts:

Nuclear sclerosis – general clouding, hardening and darkening of the lens.

Posterior subcapsular – white opacification develops on the back surface of the lens

CataractIn Human EyeCortical – white spokes develop in the periphery of the lens and migrate towards the center

Signs and symptoms

As a cataract becomes more opaque, clear vision is compromised. A loss of visual acuity is noted. Contrast sensitivity is also lost, so that contours, shadows and color vision are less vivid. Veiling glare can be a problem as light is scattered by the cataract into the eye.


Cataracts develop for a variety of reasons, including long-term exposure to ultraviolet light, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age, or trauma (possibly much earlier); they are usually a result of denaturation of lens protein.


When a cataract is sufficiently developed to be removed by surgery, the most effective and common treatment is to make an incision (capsulotomy) into the capsule of the cloudy lens in order to surgically remove the lens.   Dr.Thomas performs this surgery under local anesthetic, using a sutureless technique.

He performs the surgery using local anesthetic and the patient goes home that day with a patch or shield over the eye.  The surgery takes approximately 20 minutes to perform.
High frequency sound waves (phacoemulsification) are used to break up the lens before extraction.
The cataractous lens is removed and replaced with a plastic lens (an intraocular lens implant) which stays in the eye permanently.

From Wikipedia, the free encyclopedia


This information is presented for education purposes, to make it easy for you to explore your vision correction options. HOWEVER, no matter how reliable information on this or any website may be, there is no substitute for a professional examination of your eyes and a face-to-face discussion of your unique situation. If you are experiencing any difficulty with your vision, you should schedule an eye examination.