A Pilot with Decreased Vision

Transcription

1 A Pilot with Decreased Vision Christopher T. Bird, MD, MS Lt Col, USAF, MC, SFS Clifton M. Nowell, DO, MS Maj, USAF, MC, FS USAF School of Aerospace Medicine WPAFB, OH RAM

2 Disclosure Information 84th Annual Scientific Meeting Drs. Christopher Bird and Clifton Nowell We have no financial relationships to disclose. We will not discuss off-label use and/or investigational use in our presentation. 2

3 History 34-year-old male A-10 pilot with 1832 total flying hours In 2001, member underwent PRK to correct his myopia OD and x015 OS with visual acuity 20/200 OD and 20/160 OS PRK surgery was successful and member s uncorrected visual acuity was 20/20 OD and OS 3

4 History In 2010, subjective visual acuity noted to be diminished and he felt like he needed a new prescription OD Visual acuity was noted to be 20/20 Denied any eye pain, discharge, redness, visual field defects, vertigo, headaches, or dizziness Seen by optometry who noted an inferior visual field defect within 20 of fixation OD 4

5 History Ophthalmology evaluated him and concern for normal tension glaucoma OD was raised visual acuity was noted to be 20/25 OD; 20/20 OS Intraocular pressure (IOP) was 13 mmhg OD and 14 mmhg OS Pupillary exam and EOM were normal; slit lamp exam was unremarkable A dilated fundus exam revealed a 0.7 cup/disc ratio OD with mild degree of pallor and a 0.5 cup/disc ratio OS 5

6 History Visual field testing showed inferior arcuate/ incomplete inferior hemi-field defect in the right eye He was started on Xalatan OU qhs, Combigan OD bid, Azopt OD tid Eventually meds changed to Timolol and Xalatan Referred to the Aeromedical Consult Service for evaluation as part of waiver process to return to flying 6

7 Past Medical History Adult Illnesses: Allergic rhinitis, myopia, glaucoma Surgeries: PRK, ORIF left navicular fracture Hospitalizations: None Aeromedical: No mishaps or incidents PPD/Immunizations: Up to date Allergies: NKDA Medications/Supplements: Aspirin Social: No tobacco use, social EtOH (1-2 drinks/week), occasional caffeine use, exercises regularly 7

8 ACS Work-Up Unaided Visual Acuity: OD Dist 20/25 Near 20/20 OS Dist 20/25 Near 20/17 Present Correction: OD: x095 Dist 20/30 Near 20/25-1 OS: x110 Dist 20/15-2 Near 20/15 Manifest: OD: x090 Dist 20/20 Near 20/20 OS: x110 Dist 20/15-1 Near 20/15-1 8

9 ACS Work-Up Cycloplegic OD: x095 Cycloplegic OS: x100 Gross External Exam: Lids: Normal OU Conjuctiva: White & Quiet OU Adnexa: Normal OU Pupils: 4 mm, round, afferent pupil defect present Confrontation Fields: OD Abnormal, OS Full 9

10 ACS Work-Up Color Vision PIP OD: 14/14 OS: 14/14 PIP2 OD: 09/10 OS: 09/10 Without Rx Depth Perception: VTA-DP: A-E PASS With Rx Depth Perception: VTA-DP: A-F PASS Intraocular Tension By Applanation: OD 14 OS 16 Ophthalmoscopy: Discs: Sharp: c/d ratio OD: temporal thinning and +1-2 pallor; OS: 0.5 Macula: Normal OD & OS Vessels: Normal caliber and appearance OD & OS Periphery: Normal OD & OS 10

11 Special Studies Contrast Sensitivity: Abnormal OD & Normal OS - stable Humphrey Visual Field (HVF): Incomplete inferior arcuate (within 10 of fixation) OD & Normal OS Binocular HVF: Normal OU HRT: Normal OD & OS 5% PV: 20/39.9 OD & OS PASS OrbScan/Pentacam/Corneal Topography consistent with CRS history OCT RNFL: Diffuse thinning OD (mostly superior) & normal OS consistent with HVF Gonioscopy: Open OU no occlusion OU 11

12 Special Studies FM100: OD: 40; OS: 16 normal Wavescan: OD: 0.7 (0.33 w/ RGP) OS: 0.30 US Pachymetry: OD: 596; OS: 533 normal Anomaloscopes: Normal on Rayleigh Abnormal on Moreland OD VEP: Abnormal OD consistent with optic neuropathy OD CCT: Abnormal OD (R50 G50 B55) & OS(RGB 100) 12

13 Retinal Images 28 Jul 2011 OD OS 13

14 Retinal Images 13 Sep 2012 OD OS 14

15 Physical Exam Gen: 34-year-old male in NAD, alert and oriented HEENT: NC/AT, TMs clear, Valsalva normal, EOMI Pulmonary: CTAB with no W/R/R CV: RRR with no M/R/G, pulses present and strong bilaterally Abdomen: Soft, NT, ND, no hepatosplenomegaly Neurological: CN II-XII grossly intact Ext: Normal ROM all extremities, no C/C/E 15

16 Diagnoses 1.Optic neuropathy OD, with medium-term stability, most likely caused by nonarteritic anterior ischemic optic neuropathy (NAION) 2.Optic disc sectoral pallor OD secondary to diagnosis #1 3.Monocular inferior altitudinal visual field defect adjacent to fixation OD, secondary to diagnosis #1 16

17 Diagnoses Acquired dyschromotopsia (protan, deutan,& tritan defects) OD, secondary to diagnosis #1 History of photorefractive keratectomy OD and OS (22 Jan 2001, WHMC, pre-op cycloplegic refraction Sph OD, & x015 OS), good outcome, stable Use of RGP contact lens OD, due to high secondary aberration s/p PRK 17

18 Pathophysiology NAION can be due to either of two mechanisms: The first, and most common type, is thought to be caused by transient hypoperfusion of the optic nerve head (ONH) circulation The second type is due to an embolism to the arteries or arterioles feeding the ONH 18

19 Risk Factors Predisposing risk factors make the ONH vulnerable to ischemic disorders These may be systemic or local 19

20 Risk Factors Systemic risk factors seen in NAION patients: Hypertension Diabetes mellitus Nocturnal arterial hypotension Ischemic heart disease Hyperlipidemia Atherosclerosis ED medications 20

21 Risk Factors Ocular risk factors: NAION is significantly associated with absent or small cup in the optic disc Disc at Risk Optic disc drusen History of cataract extraction Elevated IOP Optic disc edema due to any cause 21

22 Precipitating Event When predisposing risk factors are present, a drop in arterial blood pressure is hypothesized to cause the NAION event Most individuals note the symptom of visual loss from NAION upon awakening 22

23 Clinical Features NAION is usually diagnosed in middle-aged and elderly patients Sudden deterioration of vision On occasion, it occurs in the younger population Painless Usually discovered upon awakening Photophobia can develop Visual acuity can be normal However, visual field defects are almost always present 23

24 Clinical Features Ophthalmic evaluation demonstrates optic disc edema Can have associated optic nerve hemorrhages Resolves spontaneously, usually within 6-8 weeks After the edema has subsided, generalized pallor of the optic disc can be seen 24

25 Management Management of NAION is controversial Optic nerve sheath decompression was once thought to be an effective treatment in NAION patients, but has now been proven to be ineffective and potentially harmful Aspirin is thought to help in preventing NAION from progressing, but this recommendation is anecdotal Systemic corticosteroid therapy is helpful in arteritic AION, but generally not recommended for NAION 25

26 Management Since NAION is a multifactorial disease, possibly the most useful management strategy is to try to evaluate and reduce as many risk factors as possible Goal is to reduce the chance of NAION developing in the second eye Can also reduce risk of future episodes Additionally, timing of antihypertensive medications can be modified to prevent NAION Given that nocturnal arterial hypotension is a major precipitant of NAION in patients at risk, cautioning patients not to use these meds at night can help prevent this condition 26

27 Risk Assessment From a binocular standpoint, this pilot has little functional decline, as he has normal binocular visual fields However, he still lacks peripheral stereopsis in his right inferior visual field 27

28 Risk Assessment In approximately 6% of patients, same eye recurrence occurred within 2 months to 21 years Due to the fact that this pilot has developed AION OD, he is still a significant risk for having recurrence in his OD and possibly occurrence in his OS This risk is substantially increased with flying high-performance aircraft under G To mitigate the risk of his optic neuropathy and accompanying color vision deficit, FC IIC waiver is recommended with the following restrictions: 1. No high-performance airframes 2. Multi-place aircraft with another qualified pilot 28

29 Recommendations Disqualified for FC II duties secondary to all diagnoses Optic neuropathy, optic disc pallor, visual field defect, dyschromotopsia, PRK, RGP lens use FC IIC waiver for all diagnoses (except PRK), restricted to non-high performance, multi-place aircraft with second qualified pilot, as well as his current and all previously assigned airframes, valid for 2 years Indefinite FC II waiver recommended for PRK Daily baby aspirin to reduce risk of ischemic optic neuropathy recurrence or fellow eye involvement 29

30 Recommendations Every 4 months Humphrey 30-2 perimetry with review by local MTF ophthalmology Prophylactic IOP-lowering medication OD (tolerated Xalatan well in past) for optic nerve protection, to be started and managed by local ophthalmologist Spectacles or contact lenses ARE required for all aircrew duties, with back-up pair of spectacles on person at all times 30

31 Aeromedical Disposition USAF USN AFI G NAMI MANMED Chapter 15 Section 4.5 USA AR Chapter 4-11 Eyes, f. Optic nerve FAA CFR Title No acute or chronic pathological condition of either eye or adnexa that interferes with the proper function of an eye, that may reasonably be expected to progress to that degree, or that may reasonably be expected to be aggravated by flying. 31

32 Bibliography Arnold AC. Pathogenesis of nonarteritic anterior ischemic optic neuropathy. J Neuroophthalmol 2003;23: Ehlers JP, Shah CP, eds. The Wills eye manual: office and emergency room diagnosis and treatment of eye disease, 5th ed. Philadelphia: Lippincott Williams & Wilkins; 2008: Hayreh SS. Ischemic optic neuropathy. Prog Retin Eye Res 2009;28: Ischemic Optic Neuropathy Decompression Trial Research Group. Optic nerve decompression surgery for nonarteritic anterior ischemic optic neuropathy (NAION) is not effective and may be harmful. JAMA 1995;273: O Neill EC, Danesh-Meyer HV, Connell PP, et al. The optic nerve head in acquired optic neuropathies. Nat Rev Neurol 2010;6: Sohan SH. Management of ischemic optic neuropathies. Indian J Ophthalmol 2011;59:

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39 Questions 1. Which of the following is a nearly universal sign of NAION? A. Painful loss of vision B. Erythematous sclera C. Visual field defect D. Conjunctival discharge 39

40 Questions 2. Which of the following is NOT considered a predisposing risk factor for NAION? A. B. C. D. Diabetes Elevated IOP Hypertension History of strabismus 40

41 Questions 3. Possible effective strategies for treatment of NAION include: A. Corneal transplant Risk factor mitigation Steroids Optic nerve sheath decompression B. C. D. 41