What is undercorrection? (posted: jan 2005)

Uncorrection occurs when too little tissue is removed from the cornea, with the result that the target refractive error is not achieved.

How does an undercorrection happen?(posted: jan 2005)

Undercorrection happens to a certain number of patients and the reasons are not entirely clear. Sometimes the laser's correction profile (nomogram) may need adjustment. There are environmental factors such as humidity that affect the ablation process and have to be compensated for but this compensation is not always precise. Sometimes there are anomalies of individual patient healing.

Are some patients more likely to be undercorrected than others? (posted: jan 2005)

Yes. Patients with high or unusual prescriptions are more likely to be undercorrected. This includes patients with high or very high myopia; with hyperopia; with large astigmatism; or with mixed astigmatism. In the clinical trial data submitted to the FDA for approval of excimer lasers and which end up as part of the permanent device labelling, there are normally specific indications of what percentage of each type of patient has been undercorrected or required a retreatment.

How is undercorrection different from regression? (posted: jan 2005)

In undercorrection, either not enough tissue is removed during surgery or healing factors in the period immediately following surgery result in residual refractive error. Regression is more of a long-term process and can occur at any time after surgery.

What can be done about an undercorrection? Should I get an "enhancement"? (posted: jan 2005)

There are basically two ways to deal with undercorrection. If it is large enough that vision correction is necessary, one can either wear glasses or contact lenses, or can have additional surgery. It is important to give all the options serious consideration. While "enhancement" (retreatment) is frequently performed, it must be recognised that it constitutes eye surgery just as serious as the primary procedure and in fact carries certain additional risks. We recommend that you review our articles about retreatments before making this decision.

Where can I learn more about undercorrection? (posted: jan 2005)

Click here for Encyclopedia entry, which may have additional articles and links.