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

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Presentation on theme: "Aviation Ophthalmology Wg Cdr Malcolm Woodcock RAF Ophthalmology Royal Centre for Defence Medicine."— Presentation transcript:

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 Pilots at Combined Velocity of 1,200 Mph

6 90% thickness keratotomy Radial keratotomy (RK)  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  Painful due to de- epithelialisation  Corneal stromal haze – Reduced corneal sensitivity – % lose >2 Sn lines  Ablation edge effects – Halos (night driving) – Decentred ablation

10 Laser In-situ Keratomilieusis (Lasik) Corneal flap

11 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

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  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.

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 – 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 – 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 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!) 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 Asteroid 4 Vesta Magnified Star Milky Way Pueo star field Correction of atmospheric aberrations

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  Medical standards required to maintain air safety in the face of – Changing technology – Changing experience

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   


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