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. What about laser eye surgery Doc?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 Pilots at Combined Velocity of 1,200 Mph

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

7. Photorefractive Keratectomy (PRK)

8. Pros and Cons of PRK 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

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

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

11. Pros and cons of Lasik Reduced haze Increased ablation area Painless
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
Diffuse Lamellar Keratitis - Non-severe forms have been estimated to occur in 1% of cases; severe cases comprise only about 1 in 5,000 surgeries.5 A number of names including Sands of the Sahara have been used to describe this condition, which is characterized by an accumulation of inflammatory cells under the flap. The condition usually appears at one to three days after LASIK. However, there have been recent reports of late onset DLK.6-7 Multiple causes have been hypothesized, but no single explanation accounts for all cases. Rx intensive topical steroids.
5. Steinert, RF. Swami, AU. Diffuse Interface Keratitis. Review of Refractive Surgery, January
6. Yeoh J, Moshegor CN. Delayed diffuse lamellar keratitis after laser in situ keratomileusis. Clin Experiment Ophthalmol 2001 Dec;29(6): Chang-Godinich A, Steinert RS, Wu HK. Late occurrence of diffuse lamellar keratitis after laser in situ keratomileusis. Arch Ophthalmol 2001 Jul;119(7):1074-6

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

14. USN PRK Study 2002 1035 patients 84% no gls 4 weeks 95% 6/6 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.

15. 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.

16. Other Techniques Clear lens extraction Phakic intraocular lenses LASEK
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 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

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
Aircrew are normally recruited before ocular maturity and at an age when CRS may not provide long-term refractive stability.
Furthermore, the long-term outcome of CRS in trained aircrew needs to be evaluated before considering the procedure for potential aircrew.

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
Asteroid 4 Vesta
Milky Way
Pueo star field
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. Congenital Colour 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 So watch this space.....
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:

33. Wg Cdr Robert A.H. Scott
Defence Consultant Adviser in Ophthalmology Royal Centre for Defence Medicine Selly Oak Hospital
Raddlebarn Road
BirminghamB29 6JD