82% of US Air Force personnel opt to undergo PRK eye surgery

82% of US Air Force personnel opt to undergo PRK eye surgery

Speed, accuracy and efficacy are three reasons why the wavefront-optimised laser is a solid performer.

Refractive surgery is not cosmetic surgery, although the desire to be rid of spectacles and contact lenses may play a part in patient motivation. In the military, refractive surgery is limited to PRK and Lasik. We are not allowed to perform phakic intra-ocular lens (IOL) implantation, clear lens exchange or conductive keratoplasty on active duty US Air Force personnel.

The Air Force allows Lasik in high-G-force aircraft personnel, including fighter pilots. Service members looking to undergo the procedure must first obtain clearance from their commanding officer and be prepared to be nondeployable for one month after Lasik and four months after PRK. These limitations can affect which type of refractive procedure the patient prefers. Also unique to the Air Force is a limit on the upper levels of hyperopia.

Eighty-two per cent of Air Force personnel opt to undergo PRK. PRK laser eye surgery has a long track record in the military, so most personnel request the procedure by name, and the successful outcomes we have had in the past with PRK are likely why it is still the most requested procedure.

Wilford Hall Medical Center at Lackland Air Force Base in Texas is one of seven Air Force centres in the US. We received a wavefront-optimised laser about 18 months ago and began using this platform to perform PRK on our Air Force personnel. This is an off-label use of the laser platform. To date, I have used it on 1,500 eyes and have six months of follow-up data on 838 eyes of 419 patients. We also recently began using the wavefront-guided platform on this laser but only have preliminary results out to about one month.

In both Lasik and PRK, we have found that the wavefront versions performed better than standard ablations. There are several improvements with the wavefront-optimised platform, not the least of which is the speed of the platform, enabling a very short actual treatment time averaging about five to 20 seconds. Beyond that, the ability to personalise a treatment to a particular patient’s corneal curvature cannot be underestimated. That is one aspect of the wavefront-optimised laser I have thoroughly enjoyed.

Early results

We have data on 838 eyes with six months of follow-up. We accepted patients with refractive errors between –8.75 D and +4 D, with cylinder up to 3.75 D. All patients had opted to undergo PRK, and the ages ranged from 21 years to 60 years. In my hands, there is no nomogram adjustment needed for those with less than –4 D and under 2 D cylinder. We determined the optimal treatment method based on preop refraction and wavefront higher-order aberration root-mean-square to determine whether a wavefront-optimized or -guided ablation would be best

As with most refractive surgery, patient selection is important.

When we evaluated the percentage of eyes obtaining 20/20 vision, 93 per cent of those who had PRK laser eye surgery achieved 20/20 by 6 months. We know from our data that PRK laser eye surgery tends to improve over time, so I expect those visual results to continue improving. We are still comparing and contrasting the outcomes of wavefront-optimised and -guided PRK, but there does not seem to be any difference between the two groups in terms of speed of recovery. The Air Force’s results with wavefront-guided PRK prove the technique to be a solid performer. Although my personal experience with wavefront-guided PRK on the optimised laser system is encouraging, it is too early for any of the patients to have achieved refractive stability.

For our military personnel, when we talk about post-op quality of life, we evaluate low-contrast vision (think of a grey airplane flying in a grey sky). We know our previous wavefront-guided outcomes showed low-contrast vision improving over time, and we are now finding the same thing with the wavefront-optimised laser. The last thing we want is to give someone 20/20 vision but have their contrast sensitivity negatively impacted.

None of our patients lost more than two lines, which is within the realm of standard PRK. For those with follow-up out to one year, we have no reports of corneal haze with this laser platform. We do not use prophylactic mitomycin C, so to have no haze at this point has been reassuring. Historically, the Air Force has had low levels of reported corneal haze, so we do not feel it is necessary to use prophylactic MMC.

By six months, we have found our visual outcomes are basically the same, regardless of whether we perform Lasik or PRK laser eye surgery on the wavefront-optimised laser platforms. We have been pleased with our outcomes with wavefront PRK so far, although we recognise Lasik does offer a faster speed of visual recovery. With more than one year of follow-up on a majority of our patients, we have not had to perform any enhancements on those who underwent PRK on the wavefront-optimised laser. Not everyone is at 20/15, but no one has asked for an enhancement. About 50 per cent of our patients have achieved 20/15 at the one-year mark.

Planning times

One aspect to consider when planning surgical treatments on the wavefront-optimised laser is that the platform requires a lot fewer data points than does wavefront-guided PRK. In my opinion, the time it takes to develop a surgical plan is also condensed. Having a slit lamp on the device itself can be a useful tool when your visualisation is hampered.

Results achieved in military personnel may be unique. Our average age for PRK laser eye surgery is 32 years, so it may be unfair to compare our exemplary results to those of physicians serving non-military patients.

Our outcomes with wavefront-optimised PRK really are the ‘perfect storm’ of great technology in great hands with great patients. With almost 30% of all treatments today being PRK, we are working toward ensuring that the US Food and Drug Administration approves this technology for surface ablation.

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Disclosure: The opinions stated in this article do not necessarily reflect those of the Department of Defense or of the United States Air Force.

Charles “Chaz” Reilly, Lt. Col., USAF, MC, FS, is the chair of the Department of Ophthalmology and consultant to the Air Force Surgeon General for refractive surgery at Lackland Air Force Base, Texas.

Article Source: OSN Supersite, by by Charles “Chaz” Reilly, Lt. Col., USAF, MC, FS (September 2010)

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