I had this interesting question recently from Kevin:

Hi Doctor, Would you please advise if “zlasik” is still better and newer technology compared to “ilasik with iFS Advanced Femtosecond Laser”?  Thanks

Hi Kevin, I prefer the Ziemer system (Z-LASIK). We have the brand new Ziemer LDV Crystal Line system, currently the only one in the UK, and it is a remarkable flap creation tool. It has a 33 times faster repetition rate than the latest iFS 150KHz model, with energy per pulse far lower, tighter energy focus and the shortest suction-on time. We can do both eyes safely and very accurately in around 6 minutes.

_{»crosslinked«}

You may have seen this article on laser eye surgery in the Daily Mail last week. The article describes the serious complications suffered by Lois Roberts following her laser eye surgery 3 years ago.

Yet, instead of the simple pain-free experience Lois was led to expect, the surgery to correct her short-sightedness left her in agony for days. Worse, three years on, she still has painfully dry eyes as a result of damage to the nerves that stimulate tears. Lois has to apply eye drops daily – which in itself is a problem, as long-term use can raise the risk of chronic eye inflammation. Dry eyes can also lead to serious infections and, ultimately, even loss of vision.

As well as dry eyes, Lois suffers from constant floaters and poorer night vision. ‘The floaters are like clumps of black lines and dots,’ she says. ‘I’ve been reassured they’re harmless, but they are incredibly annoying.’

How accurate was this piece? Sadly, not very much at all. Interestingly, Lois herself added the following comments on the online version of the article:

Hi all – I’m Lois from the article I just wanted to confirm that I do NOT regret having laser eye surgery. I was shocked when I saw a huge picture of myself saying that laser eye surgery has ruined my sight! This is not true. For me personally, I don’t find the dry eyes and floaters a big problem, yes they’re annoying but hey it’s worth it for me. Also, I would never EVER have had laser surgery after watching an advert on the tv! I had it done in Manchester, the same place as my father had his done very successfully around 15 years ago. I thought this article was going to look at the positive and negative effects of laser surgery. For me, it’s great to be able to surf and play sports without having to worry about whether I’d be able to put my contacts in. Anyway, I feel better now I’ve had a little rant! Thank you for some of the lovely comments!

- Lois, North Wales, 01/12/2010 11:04

Another reader, Andy, added his feelings on this:

Thankful that Lois has been able to put in a comment that counters the sensationalism of this article … But you do get what you pay for! … There are enough alternative, highly rated clinics out there with fantastic reputations that you can choose from. Do not undervalue your eyes – laser eye surgery IS surgery and should not be treated like buying anything else on the high street. Please do your research into laser eye surgery clinics and you will avoid the problems detailed in this sensationalist article.

- Andy, Guildford, Surrey, 01/12/2010 17:30

You should look around carefully before choosing the clinic and surgeon for your laser eye surgery. You get one pair of eyes, after all. If you are unlucky enough to need to wear glasses, laser eye surgery is a realistic option and safe in the right hands. The latter emphasis is important. For example, dry eyes occur in those who had dry eye before the procedure, and these patients should not have LASIK.

Julie asked:

Dear Dave, I am about to get an enhancement surgery since my eye changed to -1.0 after just 10 months. I got the flap cut with the laser. I see that this type of cut heels quickly and I know doctor will not be using the cutting laser again, so how is he going to lift the flap? I’m terrified and thinking that I will be better off wearing glasses again. What do you think?  Thank you

Hi Julie
We lift flaps manually, using a special instrument designed for lifting, which is usually a fairly simple process. It should be possible to lift a femtosecond flap at 10 months, but you wont know until it is tried. I had one patient that proved impossible to lift after 6 months, but that was unusual. You could opt for PRK enhancement with mitomycin, but I would opt normally to lift the flap first. You can discuss this with your surgeon before going ahead.
We are now hitting 100% for patients seeing 20/20 or better at my clinic, Focus, so enhancements are getting increasingly rare. If they do happen, it is usually for patients with very high myopia.
Best regards, Dave

Meera asked

Graeme just asked:

Hi Dave,

Two weeks ago I was treated with wavefront guided LASIK with Intralase by [clinic name deleted].

Although my vision was very good from the following day, I have had problems at night with severe starbursts, glare and halos around fluorescent lights (even indoors). I was told a couple of days ago that it will get better with time but since it’s hardly got better since day 1, I think there is a slim to no chance of this happening, especially as the eyes otherwise feel good with excellent vision.

Also, I was told a number of times that I had very large pupils which is why I needed wavefront guided LASIK to prevent my night visiion being affected. In hindsight and reading further on the Internet (which I now realise I should have done much more of) .

I guess I’m asking is there anything that I can do about this, anything I should ask them, e.g. pupil dilation, treatment area or anything like that to determine the reason for the starbursts and the fact that it hasn’t been done 100% correctly or I shouldn’t have been recommended as suitable? Or is there anything that can be done to improve it?

I wouldn’t obviously want further surgery but I’ve seen on this page info about more modern lasers and larger treatment areas that you have used which almost eliminate night vision problems. Could this be an option? Although I have paid out £3000 so far and so wouldn’t welcome another big outlay especially without guarantees of success. My main problem is that come the winter I won’t even be able to get to work if my night vision remains as bad as this.

I would be grateful for any suggestions or advice that you have.

Graeme, it is still very early after your treatment, so I think the advice from your clinic to wait is correct. I would normally allow 2-3 months for the vision to settle fully before looking if anything else needs doing, especially if it was a particularly large prescription. So please be patient for now.

Keep in contact with your clinic, and repeat testing at 4, 8 and 12 weeks post-op can help monitor your progress and relieve anxiety. You would want refractions and wavefront scans in particular, as night problems can arise from both low and high order aberrations. Low order means your prescription, but from your description your distance vision is excellent so not likely to be much prescription left – but you can confirm at your next visit.

It can occur if the treatment zone was significantly smaller than the scotopic (dark conditions) pupil size but clinics and doctors are well aware of this and modern lasers can treat a wide area of the cornea. You can ask about your dark pupil size and the full optical zone used at your treatment, as well as the total treatment zone (including the blend zone that feathers the treatment edges outside of the full optical zone area).

If the night vision problems persist, treatment is usually possible and will depend on the cause. Patience first though, as these symptoms can improve significantly yet. Give them the opportunity to assess and review your progress. Please let me know how you get on.

Marie asked:

I had a detached retina 3 years ago, I have just had the go ahead from Optical Express to say i can have laser but I had been advised by the Dr who did the detachment at that time never to have it done and also by Specsavers after my annual eye test. What would you advise?

Marie, It’s a good question. Does LASIK increase the risk of retinal detachment? Or does retinal detachment, which is more commonly found in short-sighted patients who incidentally have LASIK, happen anyway ?

The suction applied by the keratome or femtosecond laser during flap creation can put tension on the vitreous gel and retina, and theoretically increase the risk of retinal problems. What evidence is there for this?

At the 2009 AAO meeting in San Francisco, Dr. J Fernando Arevalo reported no apparent causal relationship between LASIK and retinal detachment. Over 11,500 eyes were examined retrospectively and the incidence of retinal detachment was found to be lower than the general population. The study included patients that developed a retinal detachment as far out as 13 years after the procedure.

In a 10-year review presented by Dr Vincenzo Pucci MD at the 2003 ASCRS international eye conference, laser refractive surgery for high myopia did not appear to increase the risk of either retinal detachment or re-detachment. His series comprised 2,809 eyes of 1,477 patients who had undergone either LASIK or PRK for the correction of myopia or myopic astigmatism up to -13 dioptres.

Together these studies support the conclusion that the retinal detachment rate after excimer laser surgery for the treatment of high myopia is not increased, compared with the natural history of unoperated myopic eyes.

In my practice, for a comprehensive safety approach, I usually have the eyes examined by a retinal surgical specialist to get the all clear before any laser eye surgery procedure. Also, this specialist will review the retina afterwards to be certain no new holes or tears have appeared.

Zoe asked:

I am interested in laser eye surgery, but am very short sighted(-10) would it still be possible?

Zoe, yes it certainly may be possible. It will depend mainly on your corneal thickness and pupil size in the dark. The best way to know is to have a consultation and have the measurements taken. Not all patients are suitable at this level of prescription though. If LASIK is not possible, PRK with mitomycin may still be.
The WaveLight laser that I use takes relatively little tissue per dioptre, so I find we often have a good chance to treat higher myopia. If there is not quite enough tissue in the cornea, and you are 40+, a good option can be to leave you between -1D and -2D, so at least you will be able to read without any glasses.

Anthony asked:

Hi Dave
I am 67 years old and currently use daily contacts. Left eye D + 1.50 Right D + 1.75, the left eye has a slight astigmatisum. I use + 2 reading glasses. I have been told that due to some mild furring around the edges of the cornea, expected at my age, I will need Intra – Ocular Lenses, one for long distance and one for reading. Also I have some dryness in both eyes, again expected at my age.
Do you think I am too old and would Z-Lasik be able to correct my vision in both distance and reading or just distance. I live in London so travelling to Wimpole Street is not a problem should I decide to have a consultation.

My reply was:
Hi Anthony, Certainly not too old, and I have done blended vision for patients in their 70s. All depends on the condition of your natural lenses and presence of any cataracts. Sometimes IOLs can be the better choice but not always. Your prescription is certainly in range of those I treat for correcting distance and near. Dryness can be assessed and treated if not too bad. If severe, would likely be a block to laser eye correction, but not to IOLs.

We can certainly have a look at consultation with one of my team as a first step. Price wise, the IOLs are the more expensive option, at £2,500-3,000 per eye, the latter being if you opt for multifocal lenses to help with reading and distance. Laser blended vision is £2,200 per eye, again correcting far and near.

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.

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.

I was recently asked by Kaz to explain the Z-LASIK procedure in more detail. Watch this video and in a second post I will run through why I consider Z-LASIK combined with the WaveLight excimer laser to be the ultimate in LASIK laser eye surgery.

One of the most common questions I get asked is how to choose where to go for their laser vision correction. I talk about the 5 ‘secrets’ to choosing a laser eye surgery clinic, which many patients have found helpful. This is now available as a download from Focus.

Click here to sign up to immediately get the information directly from their site.

Do send me some feedback if you find the information helpful. If there is something else that you want to know, post a comment below or send me a message through the box in the right sidebar.

Here is a question on LASIK flap healing received this week:

Hi Dave,

I recently got custom lasik done on April 29 2010 with a microkeratome. I’m worried now because im reading all this stuff on how the flap never really heals. How easy is it to dislodge the flap? And How worried should i be and can they amputate the flap if it ever becomes dislodged?
thanks Dave

In reply, I said that yes, it is true that the flap interface does not heal strongly when cut deeper, as with most (blade) microkeratomes. It is possible to lift those thicker keratome flaps even years later. However, the flaps will not move with normal daily life activities, and are only at risk with direct significant trauma. There are case reports of flaps moving with direct injury, including an air bag, but these events are rare for most people so you don’t need to worry.
However, the better healing at the interface of thin flaps is one of the reasons for the introduction of femtosecond lasers, which is now available at 80% of UK clinics. I have written on this topic in more detail before, but am sure we will come back to it.

Here is a recent question I was asked on whether LASIK is suitable for thin corneas:

“Dear David, I wrote a while ago to ask whether Z Lasik gave greater scope to those of us with thin corneas for having Lasik as opposed to Lasek or PRK. At the time, I didn’t know what my actual measurement was – I have since had my notes from my previous check and they read L 465, R 473. However, reading recent posts on your blog I see that you do not recommend any ‘flap cutting’ to anyone with a corneal thickness measurement of under 500. I suppose what I’m asking, is if that is completely set in stone? Does Z Lasik not allow you to consider previously borderline cases?“,

And another question on the same topic:

Hi Dave,
I have myopia of -6.5 and -2 for astigma. I have a corneal thickness of 490 micron. I went for 2 different consultations. One surgeon recommend that i should do PRK because he said that it is safer than iLasik (intralase) due to zero flap create. The other doctor recommended me to go with Intralase because he said that it is possible. I know that both procedures are safe. But i am just a bit concern in the long term. Also, what is the down side of having intralase over PRK or the other way around?

Average central corneal thickness is 530-540 microns. Many surgeons, myself included, don’t cut LASIK flaps in corneas less than 500 microns, although there are surgeons who will. In the first question, this person had very thin corneas (465 and 473 microns) and in my opinion should NOT have LASIK. In the second, the corneas are thin at 490 microns, but not excessively so.

It is true that being able to create very accurate LASIK flaps with the new femtosecond lasers (e.g. Ziemer, Intralase, Zeiss) leaves more tissue behind and so allowing larger treatments. More on this topic in my next post.