Expert Commentary: Michael Rosenberg, M.D. 10/22/2009

Posted by Admin on October 22, 2009
If one looks critically at headlights, streetlights, digital clocks or similar localized light sources at night, most individuals will be aware of some halos and starbursts whether they have had LASIK or not.  These halos are ascribed to certain inherent imperfections (or aberrations) in the eye resulting in subtle vision issues that are not necessarily corrected by wearing glasses or contact lenses.  In the dark, when the pupil is larger to let more light in, the light entering the eye passes through the aberrations, resulting in the halos and starbursts.  Modern laser surgery usually uses some type of “custom” treatment that attempts to eliminate or reduce aberrations in addition to reducing the patient’s near-sightedness or far-sightedness.  The diameter of such “custom” treatments is usually about 8 mm. (The diameter of non-custom “conventional” treatment is about 6.5 mm). Even when receiving “custom” treatments patients are counseled to expect an increase in halos and starburst immediately after the procedure due to acute tissue changes and dryness. In most patients, the halos and starbursts will gradually decrease and stabilize at a level that is not disturbing. Persistent night vision phenomena may be due to a persistent refractive error (that is residual near-sightedness or far-sightedness) or new aberrations induced by the treatment. The former may be corrected with retreatment, the latter may or may gradually resolve.

One of the controversies in LASIK surgery is whether a larger pupil size in the dark prior to corrective surgery is associated with more post-operative night vision issues. This sounds logical, since a larger pupil will result in incoming light entering a larger area of aberrations. Despite the apparent logic, studies about the outcomes of patients with large pupil diameters (8 mm or more in patients receiving custom treatment, 7 mm in patients receiving conventional treatment) have shown that larger pupil diameter is not significantly associated with post-operative satisfaction. The reality is that the uniqueness of a individual patient’s eye, may have more to do with post-operative night vision phenomenon than pre-operative pupil size in patients having uncomplicated LASIK.. 

With this in mind, what should a typical LASIK patient to expect to hear from his/her surgeon during the informed consent?  They should be told that there will be an immediate but temporary increase in night vision issues. They should be told of the expectation that the halos and starbursts will steadily decrease and only rarely be severe enough to interfere with night driving.  Patients with pupil sizes in the dark greater than 8 mm may be at a slightly greater risk for having more post-operative night vision phenomena and should consider custom treatment. Finally they should be told that the most common causes of persistent night vision phenomena is temporary dryness and/or incomplete correction of the initial eyeglass correction, both of which can be corrected.

What the surgeon should expect is that an informed patient will make the best decision for himself or herself and that an uninformed patient is destined to be unhappy.

Michael Rosenberg, M.D.

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