1 / 53

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.

gusty
Télécharger la présentation

Grand Rounds Case Presentation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related