Pros and cons of Lasik Reduced haze – Bowman’s layer preserved Increased ablation area – decentration less problem – Higher myopes treated Painless – No de-epithelialisation Flap loss / damage – Ejection risk – Trauma risk Unknown time to flap stability Retinal detachment – Suction ring Sands of Sahara
LASIK vs. PRK Flap decentration of lasik Raised IOP of lasik Pain of PRK Equal correction of myopia 1-3 dioptres Lasik more accurate 3-6 dioptres SE of glare, halos, reduced night vision – Different proportions but equal effects
US Navy Experience 30/30 naval aviators av –3.25d – All achieved 20/20 unaided – Glare / halo transient – Night vision worse (1 declined other eye) No effects on NFL of PRK African Americans have excellent outcomes No effect on PRK from ejection – NFO S-3B Viking Schallhorn SC et al. Preliminary results of PRK in active duty United States Navy personnel. Ophthalmology 1996 Jan;103(1):5-27.
USN PRK Study 2002 1035 patients 84% no gls 4 weeks 95% 6/6 or better 99% 6/9 or better 150 pilots Target recognition – 98% better – 2% worse 82% better carrier landing 98% better instrument reading Schallhorn S, Tanzer D, Fulton D. Update on refractive surgery in Naval aviation. Presented at the Aerospace Medical Association 73rd annual meeting, Montreal, Canada, May 2002.
USAF PRK study 80 subjects 20 controls 20% required correction postop – Aimed for –0.5d postop refraction No effect from altitude No effect from G loading No decrease in HUD readability Tredici T, Ivan D Results and conclusions of the USAF Photorefractive Keratectomy (PRK) study. Presented at the Aerospace Medical Association 73rd annual meeting, Montreal, Canada, May 2002.
Other Techniques Clear lens extraction – For high myopes – Danger of RD Phakic intraocular lenses – May cause lens opacities LASEK – PRK without the pain
Current State of Play for Civilian Applicants JAR class 1 certification – Preoperative refraction to dioptres – Must be examined by eye specialist at CAA medical div Gatwick – 1 year before certification JAR class 2 certification – Preoperative refraction to dioptres – Ophthalmic report about surgery and its results to AME – 1 year before certification
Current Pilots – When Can They Fly? JAR class 1 recertification – Must be examined by eye specialist at CAA medical div Gatwick Stable refraction Stable refraction – 6/12 to 1 year before certification Class 2 recertification – Ophthalmic report about surgery and its results to AME
RAF Refractive Surgery (Currently!) RAF Refractive Surgery (Currently!) Cost to be borne by the individual To be performed under conditions of strict audit by DMS consultants To incorporate latest wavefront technology Grounded for 6/12-1 year until refraction stable Not accepted in recruits
Super Vision!!! Monochromatic aberrations Visual potential lies between 6/3 – 6/2
Wavefront Optics for Astronomy Asteroid 4 Vesta Magnified Star Milky Way Pueo star field Correction of atmospheric aberrations
What if it goes wrong? Well, that’s tough Risks of significantly reduced vision extremely small That risk borne by individual No compensation Remedial treatment not taken on
Congenital Colour Vision Defects Sex linked red / green Blue / yellow very rare (Homozygotic) Current tests are for red / green defects
Acquired Colour Vision Defects Predominantly affects blue / green discrimination Disease – Macular blue / yellow – Optic nerve red / green Drugs – Inc alcohol, tobacco and OCP – ‘Viagra blue’ Old age
Electronic Flight Instrumentation Systems (EFIS) Increase information to aircrew through use of coloured screens Use blues and yellows as best contrasting colours for normal vision
EFIS Issues Effect of colour vision defects uncertain – Colour anomalous – Acquired defects – No research Blue / yellow testing? – Periodic for acquired defects?
Holmes Wright Lantern No longer made Long term replacement needed Fletcher CAM test a possibility but not fully tested or validated
Conclusions Medical standards required to maintain air safety in the face of – Changing technology – Changing experience
Wg Cdr Malcolm Woodcock Department of Ophthalmology Worcestershire Royal Hospital Tel:
Wg Cdr Robert A.H. Scott Defence Consultant Adviser in Ophthalmology Royal Centre for Defence Medicine Selly Oak Hospital Raddlebarn Road BirminghamB29 6JD