Many LASIK candidates are failed or struggling contact lens wearers who are considering surgery specifically because of their dry eye-related symptoms. Because of this, we have to expect that a significant percentage of our LASIK patients have dry eye already and are likely to be temporarily more symptomatic after surgery.

The answer, in my opinion, is not to avoid performing surgery on these patients but to treat them appropriately for dry eye during the postoperative period and, if necessary, preoperatively.

We screen for dry eye carefully, with a complete history designed to assess symptoms and environmental contributors to dryness, as well as to rule out other conditions that mimic dry eye. I find tear break-up time (<15 seconds) to be currently the most reliable objective measure of dry eye. I also look at Schirmer's, lissamine green staining, the quantity and quality of the tear lake and examine the lid margins carefully.

I do not necessarily prefer PRK over LASIK in dry eye patients, particularly now that we make customized femtosecond laser thin flaps (SBK). Intuitively, it makes sense that the thinner the flap and the smaller its diameter the less disruption there will be to the nerve plexus. Fewer nerves are cut because the lamellar dissection is shallower, and the nerves have a shorter distance to regenerate.

Dr Dan Durrie and I compared PRK to thin-flap LASIK in a contralateral eye study. The patients had no more complaints of dryness and discomfort in the LASIK eye than the PRK eye, nor could we find any difference in objective tear testing measures. Corneal sensation was also the same in both eyes. We concluded that corneal innervation is minimally disrupted with thinner flaps.

Still, dry eye should be managed proactively to ensure that the typically excellent vision experienced by LASIK patients is not compromised by dry eye symptoms. Postoperatively, artificial tears and cyclosporine therapy are both very effective in resolving symptoms.

We used to offer patients very limited guidance on artificial tear selection and use. Now we typically provide them with a high-quality tear with instructions to use it q.i.d. if they had preoperative dry eye symptoms and p.r.n. if they did not. Based on the results of a study I recently participated in, my artificial tear of choice is Blink Tears (Abbott Medical Optics). Its unique visco-adaptive formula, combined with its unique mechanism of action, helps the drop adhere to the cornea and maintain a thicker tear film for a longer period of time.

Tear comparison study

We conducted a randomized, open-label, multicenter contralateral eye study of 201 patients undergoing bilateral LASIK. Beginning one week after LASIK, patients were instructed to use Blink Tears in one eye and Optive (Allergan), Systane (Alcon), or Refresh Tears (Allergan) in the other eye for one month.

Figure 1: Patients found Blink Tears to be the most soothing and comfortable and provided significantly longer duration of relief.

Patients were then asked to complete a questionnaire about preference, blur, comfort, and relief of symptoms.

Patients overwhelmingly said LASIK improved their quality of life; that they were able to return to normal daily activities within one to three days; and that they would recommend the procedure to others. The vast majority (86%) said that artificial tears helped improve their dry eye symptoms.

Figure 2: Blink Tears also produced the least blur on instillation (Figs 2&3), making it a suitable refractive tear.

When comparing the various artificial tears, patients reported that Blink Tears most improved their vision, making images appear crisper than with the other tear products. More patients (55%) preferred Blink Tears than any other tear. Patients found Blink Tears to be the most soothing and comfortable and provided significantly longer duration of relief. (Figs 1&2). Blink Tears also produced the least blur on instillation (Figs 2&3), making it an ideal refractive tear.

This study reiterates not only the importance of proactively treating post-LASIK dry eye, but the difference that a high-quality, long-lasting, and non-blurring tear can make in overall patient satisfaction.