Anne asked:

Hi Dave,
I’ve come across a lot of comments from lasik patients re: dry eyes. Many of these did not suffer with dry eyes prior to surgery. Can this become a long-term issue as many people say they are still experiencing dry eyes 6 months down the line? Also, is it something that can be avoided through the laser used and surgeon’s experience/ability? I know that you say patients do not experience TLS with the Ziemer laser, so can the same be said of dry eyes?
You mentioned in one of your previous replies that there was someone in the Cheshire area I could go to for a consultation (with a view to having surgery with Focus), please could I have their contact details?
Many thanks, Anne

Hi Anne,
A temporary reduction in tears following LASIK happens in all cases, although many are unaware of it. It happens because the superficial corneal nerves are cut during flap creation. The cornea becomes number and the nerves have to re-grow to supply the surface with normal sensation. This takes 3-6 months with a thin femtosecond flap, longer with a thicker blade flap.

The thinner the flap, the less distance to re-grow and so the sooner the cornea returns to normal. So having patients report still having dryness at 6 months is not unusual, especially if they had a thicker flap.

In some cases of ongoing dry eye, there can have been some pre-existing deficit in the tear film or tear quality that gets exacerbated by the temporary numbness in the cornea and other factors (e.g. loss of goblet cells).

I find ongoing dryness is rare in my clinic, and I think that is because we are rigorous in diagnosing, and treating where needed, prior to surgery. Technology cannot avoid the creation of some dryness (whether symptomatic or not). However creating a thin flap with a femtosecond laser makes for less dryness of shorter duration.

But it is the skill of the surgeon and clinical team that heads of problems before they are created, by not operating on patients who may lead to later trouble. Patients with marked dry eye should not have LASIK. Some dryness though can be managed and treated pre-op and so allow those patients to still be eligible for LASIK and without long-term problems.

Anne, call one of my team on 0845 5000 500 and we can connect you with our optometrist in Cheshire for an assessment.

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Amar asked:

You mentioned using mytomycin C for LASEK procedures. Is this generally a safe drug to use on ones corneas? In your opinion, what does a femtosecond laser offer over a microkeratome procedure. Can it be said if one is better than the other? Also, in higher prescriptions, given all other parameters are met including corneal thickness, which flap creation technique would be more advisable. Can both options create buttonholes?
Thank you so much for your help, Amar

Thanks Amar. MMC (mitomycin) appears to be safe. In 2000, Majdamur and colleagues were the first to describe MMC effects on post-PRK and postradial keratotomy subepithelial fibrosis (haze formation). We have not seen significant complications with its use over the past decade and I do use it on eyes where there is greater risk of haze.
I have written plenty on femtosecond lasers and blade keratomes, and you can see those posts under the lasik and safety categories. Both can create buttonholes, but the great advantage of the femotsecond laser is that you can identify the hole without lifting the flap and so get a complication-free healing, which isn’t always the same with a blade cut. In that case, the flap is already lifted by the keratome and there are risks of scarring at the edge of the hole and possible epithelial ingrowth.
Go for the femtosecond flap if you have the option.