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Grand Rounds Case Presentation

Grand Rounds Case Presentation. Adam Hill February 5th, 2009. Meet Tom. 27-year-old male Applying to be a nuclear security officer History of refractive surgery 3 years ago Thinks it was PRK and not LASIK Was moderately nearsighted before No visual complaints or other concerns.

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Grand Rounds Case Presentation

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  1. Grand Rounds Case Presentation Adam Hill February 5th, 2009

  2. Meet Tom • 27-year-old male • Applying to be a nuclear security officer • History of refractive surgery • 3 years ago • Thinks it was PRK and not LASIK • Was moderately nearsighted before • No visual complaints or other concerns

  3. Nuclear Security OfficerJob Duties • Provide physical protection of facility • Interior and exterior, night and day shifts • Armed! • Preventative foot, vehicle, stationary patrols • Search at entry / exit points • Respond to intrusions, alarms, etc • Apprehend and detain intruders http://www.nuclearsafety.gc.ca/eng/commission/pdf/2008-08-21-Transcript-Meeting.pdf

  4. What do you thinkthey want from us?

  5. Visual Acuity • Only makes sense! • What limit? • At least the driving standard • Likely even more strict • All surveillance activitieshighly dependent onvision for threat detection

  6. Refractive Correction • Can duties be performed without correction? • Glasses can fog up, slide off nose, get wet from rain/snow • Safety of officer in case of confrontation • Shatter-resistant lenses, durable frames • Contact lenses can irritate or dislodge • Need to consider both UCVA and BCVA Johnson CA. Occupational psychophysics to establish vision requirements.Optom Vis Sci. 2008 Oct;85(10):910-23.

  7. Ontario’s Requirements • Uncorrected VA of 20/40 (6/12) • Best-corrected VA of 20/20 (6/6) • That’s with both eyes open • What if Tom doesn’t make it? http://www.mcscs.jus.gov.on.ca/english/police_serv/const_select_sys/become_police_const.html

  8. Leave! • Otherprovinces,RCMP need20/60 UCVA • Everywhere needs 20/20 BCVA, at least in one eye.

  9. Hyperopia? • Ontario andAlberta arethe strictest(+2.00D in least plus eye) • Nobody else cares!

  10. Visual Field • Needed for driving • Likely much bigger field required • Seeing movements during patrol • Physical surveillance, especially with large groups of people or vehicles

  11. Ontario’s Requirements • Temporal 75º Sup.Temp 40ºSuperior 35º Sup.Nasal 35ºNasal 45º Inf.Nasal 35ºInferior 55º Inf.Temp 70º • Basically, a full field in all directions. http://www.mcscs.jus.gov.on.ca/english/police_serv/const_select_sys/become_police_const.html

  12. Huh? • These criteria sound like they were determined back when Goldman fields were the standard of care!

  13. What Test Would You Do? • 24-2 • 30-2 • Full Field 120pt • Estermann screening • Confrontation • Something else?

  14. In pictures… This is the minimum field required

  15. In pictures… 24-2 versus required field

  16. In pictures… “Full Field 120pt” versus required field

  17. In pictures… Estermann versus required field

  18. In pictures… FF120 and Estermann

  19. Visual Field • One option is to do two tests: • the Full Field 120 point, and • the monocular Estermann test • What’s the other option?

  20. Roll Your Own! Turns out this thing comes with a manual …and the manual says it’s programmable!

  21. screening test What if Tom’s doesn’t look this perfect? Quantify defects(just in case!)

  22. No problem! • Green: • Horizontal only • Yellow • horizontalplus smallvertical • Orange: • full field

  23. Colour Vision • Fairly standard test for security field • Important to recognize ID badges, people, vehicles, identify banned substances in searches, etc • Also important for monitoring alarms, signal lights, etc. • No defects permitted in any province

  24. Binocularity • No diplopia! • No eyestrain! • Stereopsis

  25. Ontario’s Requirements • Distance phoria: 5 eso to 5 exo • Near phoria: 6 eso to 10 exo • Stereoacuity: 80” of arc • Lots of people have bigger phorias than that without having any problems. • What if Tom doesn’t meet these criteria? http://www.mcscs.jus.gov.on.ca/english/police_serv/const_select_sys/become_police_const.html

  26. No problem! • As long asyou still havetwo eyeballs,there’s somewhereyou can go.

  27. Ocular Health • Must be healthy! • Great deal of resources to train staff • don’t want to hire somebody whose vision is going to deteriorate with time • especially if regular eye exams aren’t required to keep the job! • Risk of blindness from trauma • e.g. physical confrontation on-site • Only a few provinces mention this specifically

  28. Initial Thoughts • Many of these tests are part of the routine battery for a full eye exam • VA, stereo, cover test, refraction, health… • We have a visual field machine, although they don’t specify which test • What “additional requirements and specific documentation” do they want regarding the laser surgery?

  29. Tom’s Examination • UCVA 20/20 OD, OS, OU • Refraction: OD +0.25 -0.50 x 175 20/20 OS plano -0.25 x 180 20/20 • Stereopsis: at least 40” (Stereofly) • Colour vision: normal (D15) • Cover test: non-strab, ortho @ ∞ non-strab, 4 exo @ 40cm

  30. Tom’s Examination • Lids, lashes, conjunctiva healthy • Cornea clear • No sign of LASIK scars • PRK likely the procedure done • Anterior chamber deep, angles open • Pupils normal (ERRL) • IOPs 15mmHg / 16mmHg @ 10:45am

  31. Tom’sVisualFields

  32. Time to breathe! (And to read the refractive surgery paperwork he got from his truck!)

  33. Vision Stability • Only for surgeries within the last year • No significant change in refraction or acuity • “Significant” meaning > 0.50D or 3 letters on VA • Two exams at least 3 weeks apart • Tom doesn’t have to do this part.

  34. Night Vision • Bailey-Lovie Low Contrast Acuity in Room Illumination: minimum acuity of 0.20 logMAR • Bailey-Lovie High Contrast Acuity in Dim Illumination: minimum acuity of 0.30 logMAR • Bailey-Lovie Low Contrast Acuity in Dim Illumination: minimum acuity of 0.58 logMAR • Tom has to do this part! • Only need to pass two of the three

  35. 20/20 20/32

  36. 20/40 20/76

  37. What’s “Dim” Illumination? • “Illumination on the Bailey-Lovie Charts ranges from 275 to 350 lux” • Full lights in the exam room, paper chart on the wall • “Dim illumination is created by having the candidate view the charts through welding goggles with a Shade 6 filter in place.”

  38. Dr. Hovis Says • It’s based on average nighttime brightness levels for unlit streets • Required acuities derived from non-surgical control group performance • Most people don’t have significant changes • The ones that do are way off • > 3 standard deviations away • These are the people who we need to screen out! Hovis JK, Ramaswamy S. Visual function of police officers who have undergone refractive surgery. Am J Ind Med. 2006 Nov;49:885-94.

  39. What Would You Do? • We might be able to do it, but we don’t know for sure. • If we can’t, what’s Tom’s next option?

  40. Looks like quite the drive! Let’s give him the choice of doing it here,or travelling 70km to downtown Toronto

  41. The Rest of the Exam • Lens: clear • Vitreous: clear • Macula: healthy • Optic Nerve: 0.2 CD ratio OU; pink with distinct borders • Posterior Pole and Periphery: no pathology noted

  42. Welding Filters? “Let’s make that theintern’s homework!”

  43. In a nutshell… • It’s incredibly difficult to find a Shade 6 welding filter. • It’s even harder to find one withno notice!

  44. Let’s call the patient! (To let him know we’re able to do his night vision tests, of course!)

  45. Procedure • Three tests: • Low contrast acuity (room lighting) • Dim lighting acuity • Dim lighting + low contrast • Five minutes are allowed for dark adaptation (or “goggle adaptation”)

  46. Tom’s Results • Low Contrast Acuity in Room Illumination: 0.16 logMAR • minimum required acuity: 0.20 logMAR • High Contrast Acuity in Dim Illumination: 0.28 logMAR • minimum required acuity: 0.30 logMAR • Low Contrast Acuity in Dim Illumination: 0.62 logMAR • minimum required acuity: 0.58 logMAR

  47. Game Time!

  48. Greg • 18 years old • Just finished high school • Ready to join the force(or ready to apply!) • Thinks grandpa was colourblind

  49. Greg • What would you do?

  50. Linda • 24 year old woman • Did eye exercises as a child, unsure of details • No Rx; VA 20/20 • Non strab; 4 exophoria at dist, 16 exophoria at near

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