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PAM Test

Visual Testing for Cataracts

By , About.com Guide

Updated October 05, 2009

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Cataracts cause vision loss in many people. In advanced cases of cataract, surgical removal of the cloudy lens is the best treatment. Before you commit to cataract surgery, however, it's best to know how much of your vision loss can be contributed to the cataracts.

If your eye is otherwise healthy, your vision should improve to normal levels once the cataract is removed. However, some patients with cataracts may also have other eye disease that can make it hard to determine if removing the cataract will improve vision. The approximate level of vision gained can be estimated by using a PAM test, or a potential acuity meter test. A PAM test is not much more complicated than reading a typical eye chart. What makes a PAM test unique is that instead of having you look out at an eye chart on a wall, an eye chart is projected directly into your eye and onto your retina with a certain light similar to a laser, that attempts to bypass the cataract itself. Because the test bypasses the cataract, vision measured is an estimate of how much your vision may improve after cataract surgery is performed.

The PAM test is particularly useful for patients with other eye disease such as macular degeneration. Although cataract surgery is safe, risks of surgery do exist. If removing the cataract will not significantly improve vision, the surgeon and patient may decide together that it is not worth the risk of surgery, or at least wait until a later date to see if the cataract worsens.

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