Contributing factors to dry eye

Almost nine years ago Dr Edward E. Manche had not noticed any difference in dryeye symptoms after switching from the mechanical keratome to the femtosecond laser. However, as a result of anecdotal evidence that femtosecond laser flaps during LASIK might produce a lower incidence of dry eye, Dr Manche and Dr Lilya Golas performed a comparative study to determine the truth of the matter.¹

Femtosecond vs mechanical

"The outcome of the study mirrored my clinical impression between the two procedures, that there was no difference in dry eye symptoms switching between techniques," revealed Dr Manche. "The one finding that did surprise me was the difference in reported symptoms of postoperative dry eye between men and women."

The setbacks of self-diagnosis

The study was based on patient self-reporting symptoms, where each patient completed a questionnaire 1, 3, 6 and 12 months postoperatively. According to Dr Manche this self-reporting could be one of the reasons why a difference between the male and female participants was observed. He explained, "If you look at the preoperative dry-eye score between men and women, you see that women graded their reported dry-eye score as almost double that of the men. This was not surprising, as women tend to have a higher incidence of dry eye. However, postoperatively, the men had a reported dry-eye score of almost double that of women at almost every time interval."

This lower preoperative dry-eye score from the male participants could attribute to the surprising outcome. Since the baseline level of dry-eye score was lower to begin with, even a small increase in self-reported dryness might then be graded at a higher number. "This shows that additional research is needed in this area," added Dr Manche.

Dr Manche iterated that the study could have been improved and more symptoms identified if dry-eye symtoms were not self-reported. "The study could be improved by adding physical findings at the slit-lamp examination including but not limited to vital dye staining, presence of any punctate epithelial erosions, and Schirmer testing," he said.