Aviation Ophthalmology

1. Aviation Ophthalmology Wg Cdr Malcolm Woodcock RAF Ophthalmology Royal Centre for Defence Medicine

2. Should we correct the vision of military aircrew surgically? Wg Cdr Malcolm Woodcock RAF Ophthalmology Royal Centre for Defence Medicine

3. OR What about laser eye surgery Doc?

4. Introduction • Vision is the most important sense needed for flying • Vision is the only sensory means for orientation in space • Two steps in vision • At the eye • In the brain

5. VA Helps Pilotsat Combined Velocity of 1,200 Mph

6. Radial keratotomy (RK) • Diurnal variation • Variation with altitude • Regression • Weakened cornea • Unsuitable for aircrew 90% thickness keratotomy

7. Photorefractive Keratectomy (PRK)

8. 71-92% no glasses 88% rate vision good to excellent Regression 1-9% retreatment Related to level of myopia Variable refraction up to 1 year 11% dissatisfied Pros and Cons of PRK

9. Painful due to de-epithelialisation Corneal stromal haze Reduced corneal sensitivity 1.5-3.2% lose >2 Sn lines Ablation edge effects Halos (night driving) Decentred ablation Specific Complications of PRK

10. Laser In-situ Keratomilieusis (Lasik) Corneal flap

11. 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 Pros and cons of Lasik

12. 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

13. 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 dutyUnited States Navy personnel. Ophthalmology 1996 Jan;103(1):5-27.

14. 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 USN PRK Study 2002 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.

15. 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 USAF PRK study 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.

16. Other Techniques • Clear lens extraction • For high myopes • Danger of RD • Phakic intraocular lenses • May cause lens opacities • LASEK • PRK without the pain

17. Current State of Play for Civilian Applicants • JAR class 1 certification • Preoperative refraction + 5.00 to -6.00 dioptres • Must be examined by eye specialist at CAA medical div Gatwick • 1 year before certification • JAR class 2 certification • Preoperative refraction +5.00 to -8.00 dioptres • Ophthalmic report about surgery and its results to AME • 1 year before certification

18. Current Pilots – When Can They Fly? • JAR class 1 recertification • Must be examined by eye specialist at CAA medical div Gatwick • Stable refraction • 6/12 to 1 year before certification • Class 2 recertification • Ophthalmic report about surgery and its results to AME

19. 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

20. Post-operatively • Snellen Visual acuity • Refraction • Contrast acuity analysis (CAA)

21. Super Vision!!! • Monochromatic aberrations • Visual potential lies between 6/3 – 6/2

22. Wavefront Optics for Astronomy Correction of atmospheric aberrations Milky Way Pueo star field Asteroid 4 Vesta Magnified Star

23. Wavefront Analyser

24. Wavefront Images

25. 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

26. CongenitalColour Vision Defects • Sex linked red / green • Blue / yellow very rare (Homozygotic) • Current tests are for red / green defects

27. 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

28. 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

29. EFIS Issues • Effect of colour vision defects uncertain • Colour anomalous • Acquired defects • No research • Blue / yellow testing? • Periodic for acquired defects?

30. Holmes Wright Lantern • No longer made • Long term replacement needed • Fletcher CAM test a possibility but not fully tested or validated

31. Conclusions • Medical standards required to maintain air safety in the face of • Changing technology • Changing experience So watch this space.....

32. Wg Cdr Malcolm Woodcock Department of Ophthalmology Worcestershire Royal Hospital Tel: 07891 655845 malcolmwoodcock@doctors.org.uk

33. Wg Cdr Robert A.H. Scott • Defence Consultant Adviser in Ophthalmology Royal Centre for Defence Medicine Selly Oak Hospital • Raddlebarn Road • BirminghamB29 6JD • 0121-627- 8535 • 0121-627- 8922 • rob.scott@lineone.net