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LASEK – a better refractive
option for dry eye patients?
LASEK appears to offer a faster restoration of corneal sensation than LASIK in patients with pre existing symptoms or signs of dry eye syndrome, according to an Australian specialist. Speaking at the XXI Congress of the ESCRS here, Kim Frumar FRACO FRCO presented a two-year study designed to track the duration and severity of corneal anaesthesia and laser induced dry eye syndrome after LASIK and LASEK. The two year follow-up period yielded data for 186 eye in the LASIK group and 146 for LASEK. Dr Frumar and his team obtained full histories of prospective excimer laser patients particularly for dry eye syndrome. Patients underwent preoperative corneal aesthesiometry, Schirmer's testing and qualitative assessments of tear status. The researchers performed the surgeries using the Zeiss Meditec MEL70 excimer laser and Moria M2 microkeratome. Dr Frumar noted that the group of dry eye patients who had undergone LASEK showed a steady recovery in corneal sensation at three month follow-up and had fully recovered by six months. By contrast, the LASIK group showed only a small improvement at three months and six months follow-up. Moreover, the loss of corneal sensation persisted for longer than 12 months for the dry eye group.
"Breaking it down, we can say that patients who have low scores on Schirmer's tests do better with LASEK than with LASIK. We also found that patients with high Schirmer's scores have values that are significantly better than those with low values for both LASEK and LASIK," he said. He noted that tear film abnormalities often persisted for 12 months or longer for LASIK patients. By contrast, LASEK caused corneal sensory reduction that recovered after four or five months. The severity of the tear film abnormalities was also less marked in LASEK patients.
He added that the research also had important implications for any subsequent laser retreatment. "It is important to not that post-LASIK sensory loss and dry eyes will markedly reduce the accuracy of Wavefront Analysers. This makes it very difficult to treat. particularly in two-step procedures where the LASIK flap is created and a customised ablation is performed at a later stage to treat flap-induced aberrations," he said Kim D Frumar FRACO FRACS FRCO |
"It was pretty
evident when we put the numbers together that there was a statistically
significant difference between the LASIK and LASEK groups. While the data is
similar in the immediate postoperative period, there is a major difference
between what happens with the recovery of corneal sensation over 12 months
between the LASEK patients and those that had been treated by LASIK," he
said. The researchers sub-divided the LASIK and LASEK groups according to their
rating on Schirmer's test (‘low' Schirmer's, less than 12, and ‘high'
Schirmer's, greater than 12 or reflex tearing).
The study showed that
patients with identifiable dry eye syndrome experienced less post-operative
visuals symptoms and vision variation if treated with LASEK. "Our study
concluded that patients with dry eye syndrome have significantly less corneal
sensory loss and more rapid recovery with LASEK and therefore are expected to
have better outcomes," he said. He explained that the creation of a flap in
LASIK typically causes more profound and longer lasting sensory corneal
reduction or loss. Although in LASEK, the surgeon cuts the ends of the nerves in
the epithelium, even after the further ablation of nerve supply, the regrowth is
faster than after LASIK.