Pre-LASIK dry eye test needed

September 13, 2008

Doctors need to carry out a standard preop assessment for dry eye risk before undertaking a LASIK procedure. The assessment should include a validated symptom questionnarire, such as the OSDI or DEQ.

Doctors need to carry out a standard preop assessment for dry eye risk before undertaking a LASIK procedure. The assessment should include a validated symptom questionnarire, such as the OSDI or DEQ.

In adddition, doctors should test tear stability, tear flow, surface damage and potentially, in the future, using a measure of tear osmolarity as well, Dr Arun Reginald told assembled delegates at a session examinging new ocular surface insights.

Dr Reginald said that dry eye symptoms could be categorized in two ways. Post-LASIK LINE, or LASIK Induced Neuroepitheliooopathy, or as true dry eye. "They co-exist and they are not mutually exclusive. Both respond to topical treatment and both resolve after six months, " he said.

LINE showed irritative symptoms, corneal staining on the flap alone, but sparing near the hinge and a normal or reduced Schirmer's test without anaesthesia >5 mm/5 min.

LASIK dry eye also led to irritative symptoms and corneal staining in an ADE pattern as well as conjuntival staining. But it had < =10 sec for Shirmer's test without anaesthesia < =5 mm/5 min. True dry eye also indicated by tear hyperosmolarity.

"In patients who have a pre-existing unstable tear film or dry eye, there is a modified prognosis and there must be a preop and postop management plan for at least 12 months, " Dr Reginald said.

"You should consider alternative approaches, such as the femtosecond laser, which could cut a thinner flap and reduce the incidence of dry, " he said.

The use of topical cyclosporin, as is done in America, could also be used as a means of reducing dry eye preoperatively and postoperatively. "I am aware that cyclosporin is not available for this purpose, but it is something to consider when it does become available, " he said.

In his talk, Post LASIK dry eye: myth or reality, Dr Reginald noted that there was a wide variation in the incidence of post-LASIK dry eye because of confounding factors. "The use of the term dry eye or dryness is often not defined, " he said. "Sometimes two eyes are used as independent data points and there may be uncertain preop status with respect to dry eye or tear stability. "

Pre- and postop treatment is often not stated and the effect of prior contact lens wear on sensitivity is not assessed. "Different authors report on the Schirmer's test with or without anaesthetic, " he said.

He said some reported cases of dry eye could be a disturbance induced by anaesthetic used during the procedure. "Corneal denervation interrupts the reflex drive of the ocular and nasal trigeminal afferents, which drives tear flow. This reduces lacrimal secretion and causes dry eye. "

But while LINE was a real phenomenon, so too was LASIK dry eye, and patients at risk need to be identified and managed preop.