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Myths about Laser Eye Surgery

There are several fallacies, half-truths and myths that surround laser eye surgery (refractive surgery). Some of these might have been true in the past, but are no longer an issue. Others are just plain wrong.

Laser eye surgery is the most studied elective procedure in the world today, with outcomes of over 25,000 treatments analysed and published in peer-reviewed medical literature in the United States and Europe alone.

Even so, there are still many commonly held misconceptions about the treatments, some of which we can hopefully answer in the following sections. Wherever possible we’ve tried to avoid jargon – but sometimes it’s not possible to provide the information without some technical detail!

Myth 1: Refractive surgeons do not choose surgery for themselves or their families

According to a survey among laser eye surgeons for the American Academy of Ophthalmology, about 25% of surgeons have had the treatment themselves. This proportion is about four times greater than the general population.¹

The statistics for spouses and family members are equally impressive, proving that the closer you work to refractive surgery, the more likely you are to have it done.

Myth 2: Laser treatments can't correct reading vision

Many patients are told by their optometrist that they are not a suitable for laser eye surgery because they have reached the point where they need reading glasses (presbyopia).

Many of the corporate providers of laser eye surgery are unable to provide laser solutions for reading vision correction, as this may be outside the narrow range of treatments they offer.

In fact, laserand intra ocular lens (IOL) solutions for reading vision correction (RVC) exist that mirror those available with spectacles and contact lenses.

Blended monovision

Monovision laser procedures have been the most widely-used treatments. Our current treatments use ‘soft’ or ‘blended’ procedures that corrects one eye to give good vision at near and intermediate distances, while the other is corrected for intermediate to distance vision. This blended vision leaves fewer disturbances to distance sight than traditional monovision.

In a study of 310 reading vision correction treatments, 95% of patients achieved a combination of 20/20 and N5 vision at one month after treatment 13, 14

Raindrop

Raindrop is a hydrogel lens placed in your non-dominant eye as part of a standard LASIK flap that gives excellent near vision performance. It can be combined with standard LASIK treatments, to enable other vision prescription problems to be corrected at the same time as your reading vision.

SupraCor

SupraCor is the first all- laser treatment that can correct reading vision without producing a slight long-term myopia, which can sometimes be experienced with a traditional monovision approach.

Myth 3: Laser eye surgery can't correct astigmatism

Laser eye surgery can correct astigmatism, using wavefront-guided treatment, for values as high 6.00 Dioptres. The outcome for those with high prescriptions are just as good as those in patients who have low levels of astigmatism.

A recent study showed that up to 98% of eyes with astigmatism over 2.50D achieved 20/20 vision one month after treatment 2,3 .

Eye tracking technology goes hand-in-hand with the correction of astigmatism. The Technolas laser was the first to introduce true iris recognition technology and is capable of recognising every eye on the planet. This, combined with eye tracking technology, enables the laser to create the precise  alignment of treatment needed to ensure quality outcomes for patients with astigmatism 4.

Myth 4: The LASIK flap never completely heals and remains a constant potential danger

When the LASIK flap is replaced it’s initially held in position by osmotic pressure. The epithelium (the surface layer of cells covering the cornea) starts to re-grow almost immediately after treatment, and it’s safe to resume normal activity in two weeks, and even contact sport at twelve weeks, after the rest of the cornea has healed.

The introduction of the Intralase femtosecond laser to create the LASIK flap has been an important milestone in dispelling the myth of the never-healing flap. Laboratory tests show that flap adhesion is significantly stronger when created with a femtosecond laser.5  In medical literature the only (rare) recorded instances of spontaneous lifting of  the flap followed major blunt traumatic injury to the eye.

So, the presence of the LASIK flap creates no long-term risks. Even so, all laser treatments are planned meticulously, and the condition of your cornea is one of the main factors in deciding if you’re suitable for LASIK treatment 6,7 .

Myth 5: You can't wear contact lenses again after laser eye surgery

The overwhelming majority of post-operative measurements remain within the fitting range of standard contact lenses. It’s simple to fit soft lenses if required after surgery – some LASIK patients still regularly wear cosmetic contact lenses.

However, it’s true that some very rare post-surgery contact lens fitting may require an experienced practitioner’s skills:  for instance fitting  rigid gas permeable (RGP) lenses.

Myth 6: Your prescription needs to be completely stable before treatment

If you have myopia (short-sight) or astigmatism that is getting progressively worse, this might be a symptom of an underlying problem. Laser eye surgery in this situation should always be delayed until the cause of your condition is investigated. However, in those over 21 this is rare.

If you’re under 21 years of age but want treatment for occupational reasons (e.g. if you’re thinking of joining the armed forces), the combination of dramatic improvement in vision and entry to your desired occupation could outweigh the risk of your vision regressing later.

Myth 7: Dry eyes are an inevitable problem

Some decrease in tear production is a normal,common and temporary effect of the LASIK procedure. The cause is thought to be due to the disturbance of fine nerves, which run below the surface of the cornea at a depth that is similar to the thickness of a flap created using a microkeratome blade 9.

The incidence of longer-term dry eyes is greatly reduced when a  femtosecond laser such as IntraLase is used to create the LASIK flap. The thinner  flaps created by IntraLase have been shown to decrease both the severity and length of time dry eyes may cause symptoms 10.

We aim to identify significant risk factors for possible dry eye at the time of your initial visit. If  you are at risk, with factors such as age, your gender, a history of dry eyes, or signs evident during your examination (e.g. blepharitis), we may suggest either a surface treatment (such as LASEK) or a lens-based procedure (IOL) as an alternative to LASIK.

If your risk is lower, we might suggest treatments to stabilise the surface of your eyes before treatment, using techniques such as lubricants, punctum plugs or medication.

These days, any patient experiencing persistent dry eye after laser surgery is highly likely to have had the condition before the treatment. A recent study showed that longer-term problems with dry eyes after LASIK  occurs in only 0.26% of patients.

Myth 8: Laser eye surgery causes night glare

Wavefront-guided treatment was developed to avoid the problem of glare at night. The development of  ever more sensitive diagnostic equipment and more refined computer algorithms is continuing to build on this development. Technolas lasers now use 3rd generation aspheric wavefront programmes, which can produce a bespoke treatment profile, matched uniquely to your eyes and aimed at the treatment of the higher-order aberrations that lead to night glare.

A recent study showed that better visual quality occurred when these higher order aberrations are corrected 11, 12. Another recent study showed that glare was a problem after LASIK in only 0.02% pf patients.

ultralase_supp_final

Myth 9: Laser eye surgery means some future eye tests aren't possible

It’s been assumed by many optometrists that the changes to the shape of your cornea that occur during laser vision correction will prevent accurate future  measurement of the pressure inside you eye.

It’s also been assumed that biometry measurements (needed if you develop a cataract in the future) will be distorted and potentially incorrect following laser vision correction.

These assumptions have come about because tonometry and biometry measurement techniques are usually adjusted for recording information in untreated eyes. The pressure inside your eye is not altered by laser treatment, and different readings are due to calibration errors in the measurement devices and can be adjusted. Similar adjustments are available for biometry. As a result, accurate selection of  the best IOL as part of your cataract procedure is perfectly possible following laser treatments 15,16.

Myth 10: There is no long-term follow-up data to confirm stability of outcome

Most published, peer-reviewed data concentrates on the short-term outcomes of treatment. The main reason for this is the difficulty in retaining large numbers of research patients for follow-up over long periods of time.

However, a number of rigorous studies have been published in recent years, reporting long-term results of significant numbers of patients for up to 13 years. The conclusions of these studies provide reassurance of the long-term outcome quality of laser treatment 17,18.

In the largest and most comprehensive study of its kind, 389 patients were examined up to 13 years after treatment. The results revealed that the treatment achieved long-term efficacy, safety, predictability and stability, with a mean increase in myopia  of only 0.57D.

Oh yes?.. Says who?... Show me the evidence....

References
1. Duffey RJ Trends in refractive surgery; the 2009 ISRS survey AAO San Francisco 2009
2. Kohnen T, Buhren J Wavefront-guided LASIK with the Zyoptix 3.1 system for the correction of myopia and compound myopic astigmatism with 1-year follow-up: clinical outcome and change in higher order aberrations. Ophthalmology 2004 Dec;111(12):2175-85
3. Dermott J A Personalized Aspheric Treatment for Myopia Cataract & Refractive Surgery Today Europe Oct 2010 pp 24-25
4. Dermott J Zyoptix Global Alliance Meeting Report, AAO San Francisco, October 2009
5. Knorz M, Vossmerbaeumer U, Comparison of flap adhesion strength using the Amadeus microkeratome and the IntraLase iFS™ Femtosecond laser. J Refract Surg 2008 24; 875-878
6. Vinciguerra P, Camesasca FI. Prevention of corneal ectasia in laser in situ keratomileusis. J Refract Surg 2001; 17:S187– S189; errata, 293
7. Binder P Analysis of ectasia after laser in situ keratomileusis: Risk factors J Cataract Refract Surg 2007; 33:1530–1538
8. Sayegh FN Age and refraction as predictor of stability in 46 000 patients as predictor of stability of refraction after refractive surgery, J Refract Surg 2009 (Aug) 25 (8); 747-51
9. Patel DV, McGhee CNJ Mapping of the Normal Human Corneal Sub-Basal Nerve Plexus by In Vivo Laser Scanning Confocal Microscopy Investigative Ophthalmology and Visual Science. 2005;46:4485-4488
10. Slade SG, Durrie DS, Binder PS. A prospective, contralateral eye study comparing thin-flap LASIK (sub-Bowman keratomileusis) with photorefractive keratectomy. Ophthalmology. 2009 Jun;116(6):1075-82
11. Cummings A Maguire C Raytracing for corneal refractive surgery Optometry Today 2/7/2010
12. Dermott J Stanton A Brennan J Quality of Vision with Zyoptix Personalised Aspheric Treatment, Winter meeting of
the ESCRS, Istanbul, February 2011
13. Bourne A Refractive surgery for presbyopia: case histories Optometry Today 4/6/10 pp 41-45
14. Reinstein DZ Refractive surgery: presbyopic LASIK and multifocal IOL Optometry Today 3/10/08 pp30-37
15. Kirwan C, O’Keefe M, Measurement of IOP in LASIK and LASEK patients using the Reichert ORA and Goldmann applanation tonometry J Refract Surg. 2008 Apr;24(4):366-70
16. Borasio E Stevens J Smith GT Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery; the BESSt formula
17. O’Connor J O’Keefe M Condon PI Twelve-year Follow-up of Photorefractive Keratectomy for Low to Moderate Myopia J Refract Surg. 2006;22:871-877
18. Dirani M, Couper T et al Long-term refractive outcomes and stability after excimer laser surgery for myopia J Cataract Refract Surg 2010; 36:1709–1717

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