ION, spinal surgery

1. Ischemic Optic Neuropathy:
A Sequala of Spinal Surgery
Noushin S. Ahmed, O.D.
Ocular Disease Resident
Seidenberg Protzko Eye Associates
Havre de Grace, Maryland

2. Abstract
 A 63 year-old female with wet age-related macular degeneration
OS>OD presented with a new superior altitudinal defect and
decreased vision in her right eye after spinal surgery one week
prior.
 Clinical examination along with OCT and fundus photos confirmed
a non-arteritic anterior ischemic optic neuropathy (NAION).
 NAION results from interrupted blood flow to the optic nerve and
often leads to long-term vision loss, scotoma, and decreased visual
function. Hypotension, hypovolemia, and duration of surgery are
all factors during spinal surgery that can induce NAION. Incidence
of NAION as a complication is 3 in 10,000 spinal surgeries.
 It is crucial for all relevant healthcare providers to be aware of this
visually debilitating complication from spinal surgery as this
procedure is becoming more prevalent.

3. Chief Complaint
 63YO Female presents complaining of loss of vision
in the right eye since lumbar spinal surgery x 6 days
ago.
 She has also noticed a superior field loss OD as if “a
lid has come down.”
 No new floaters or flashes of light
 No pain, redness, discharge, irritation, or
photosensitivity

4. Ocular History
 Dry ARMD OD, Wet ARMD OS x 6 weeks ago
 Currently taking Ocuvite; has not received any
treatment for the Wet ARMD OS
 No changes in the HAG since diagnosis
 Wears bifocals

5. Medical History
 Allergies: Acetominophen, Penicillin, Ocycodone,
Morphine, Cefoxitin Sodium
 Diagnoses: High Blood Pressure
 Current Medications: Ocuvite, baby aspirin, HCTZ, Xanax,
Hydromorphone, Imdur, Metoprolol succinate
 Social History: former smoker; denies drug/alcohol use

6. Family History
 Cataracts: Father
 No blindness

7. Clinical Examination
External
Biomicroscopy
 VAcc OD CF @1ft PHNI
 Conjunctiva: White & Quiet OU
OS 20/80
PHNI
 Pupils OD PERRL (+) APD
OS PERRL (-) APD
 CVF
OD Sup field loss
OS FTFC
 Adnexa normal
 Cornea: Guttatae 2+ OU
 Iris: normal, (-) TID OU
 AC: deep & quiet OU
 Lens: NS 1+ OU
 IOP: 16, 18 mm Hg OD, OS

8. Fundus Examination
 Vitreous: Clear OU
 Optic Nerve: OD general disc edema, greatest inferiorly
OS flat, sharp, good color
 CD ratio: OD 0.25/0.25; OS 0.35/0.35
 Macula: OU RPE migration and multiple hard & soft drusen
 Vessels: OD arteriolar narrowing; OS normal
 Periphery: OD multiple dot&blot hemorrhages 360,
OS RPE dropout 360
OU flat 360, no holes, tears, detachments

9. Fundus Photos
 OD
 OS
drusen
artifact
Arteriolar
narrowing
ONH edema
(greatest
inferiorly)
artifact
drusen

10. ONH Photos
 OD
ONH edema
(greatest
inferiorly)
 OS

11. ONH photos
 OD
ONH edema
(greatest
inferiorly)
 OS

12. OCT ONH
Name:
CARROLL, CHRISTINE
ID:
86696
Exam Date:
9/4/2013
DOB:
6/25/1950
Exam Time:
Gender:
Female
Serial Number:
2:04 PM
5000-2788
Technician: Operator, Cirrus
OD
CZMI
Signal Strength: 7/10
ONH and RNFL OU Analysis:Optic Disc Cube 200x200
OD
OS
RNFL Thickness Map
RNFL Deviation Map
Neuro-retinal Rim Thickness
Disc Center(-0.45,-0.36)mm
Extracted Horizontal Tomogram
RNFL Thickness
ONH edema
(greatest
inferiorly)
Extracted Vertical Tomogram
RNFL
Quadrants
RNFL Circular Tomogram
RNFL
Clock
Hours
Comments
Doctor's Signature
Bel Air 5000-1
SW Ver: 6.5.0.772
Copyright 2012

13. OCT Macula
Name:
CARROLL, CHRISTINE
ID:
86696
Exam Date:
9/4/2013
DOB:
6/25/1950
Exam Time:
Gender:
Female
Serial Number:
1:57 PM
5000-2788
Technician: Operator, Cirrus
Name:
86696
Exam Date:
9/4/2013
DOB:
6/25/1950
Exam Time:
Gender:
Signal Strength: 9/10
CARROLL, CHRISTINE
ID:
CZMI
Female
Serial Number:
1:59 PM
5000-2788
Technician: Operator, Cirrus
Macula Thickness : Macular Cube 512x128
OD
ILM-RPE Thickness (µm)
OS
Signal Strength: 8/10
Macula Thickness : Macular Cube 512x128
Fovea: 213, 68
Overlay: ILM - RPE Transparency: 50 %
CZMI
OD
ILM-RPE Thickness (µm)
OS
Fovea: 247, 67
Overlay: ILM - RPE Transparency: 50 %
ILM - RPE
ILM - RPE
ILM
ILM
edema
drusen
RPE
RPE
Central
Subfield
Thickness
(µm)
ILM - RPE
Comments
Doctor's Signature
Cube
Volume
(mm³)
292
11.9
drusen
Cube
Average
Thickness
(µm)
330
Bel Air 5000-1
SW Ver: 6.5.0.772
Copyright 2012
Carl Zeiss Meditec, Inc
Central
Subfield
Thickness
(µm)
ILM - RPE
Comments
Doctor's Signature
Cube
Volume
(mm³)
Cube
Average
Thickness
(µm)
259
10.0
277
Bel Air 5000-1
SW Ver: 6.5.0.772
Copyright 2012
Carl Zeiss Meditec, Inc

14. Differential Diagnoses
 Central Retinal Artery Occlusion
 Retinal Detachment
 Perioperative Ischemic Optic Neuropathy

15. Assessment
1. Perioperative Ischemic
Optic Neuropathy, OD
2. ARMD, Dry OU
1. Refer to neuroophthalmology for consult
and evaluation.
2. Continue Ocuvite
supplement and monitor
with home amsler grid.
OCT showed no signs of
wet. Return in 3 months for
OCT of macula.

16. Blood Supply: Optic Nerve1

17. Blood Supply
 Anterior Optic Nerve:
 Central Retinal Artery
 Short Posterior Ciliary Arteries
 Circle of Zinn-Haller
 Midorbital Optic Nerve:
 Small Pial Branches from Internal Carotid Artery
 Choroid:
 Short Posterior Ciliary Arteries

18. Blood Flow
 Blood flow to the optic nerve is controlled by
autoregulation
 20% of individuals have anomalous autoregulatory function
of circulation to anterior optic nerve
 Aging, Diabetes, Arterial hypotension interrupt
autoregulation
 Higher IOP leads to decreased perfusion of retina & optic
nerve

19. Ischemic Optic Neuropathy (ION)
 Compromised blood flow to Optic Nerve
 Unilateral Optic nerve dysfunction
 Visual Field defect
 Afferent Pupillary Defect
 Decreased Color vision
 Sudden vision loss, without forewarning signs
 Painless, irreversible loss of vision

20. Ischemic Optic Neuropathy
AION1,2,7
PION1,2,7
 Swollen, pale optic nerve
 Intially, disc looks normal
(unaffected)->gradual pallor
 Anterior to the cribiform
plate
 Ischemia of midorbital optic
nerve
 Arteritic/Non-arteritic
 NAION most common
with POVL
 Associated with Giant cell
arteritis, Lupus, Sickle Cell,
Fungal Infection, and surgery
 Decrease of oxygen
availability to optic disc
 Associated with acute
blood loss
 Unrelated to ocular vascular
disease
 Most frequently reported
after spinal surgery 2° to
prone positioning

21. ION and Spinal Surgery
 ION most common (89%)1
 PION 60%
 AION 20%
 Optic nerve dysfunction occurs within 1-12 days postop2,5
 Visual changes usually occur within first 2 days
 Loss of color vision
 Visual Field deficit: central scotomas, peripheral narrowing,
quad/altitudinal defects
 Relative Afferent Pupillary Defect
 Unilateral/bilateral2

22. Spinal Surgery & Vision Loss
 Leading cause of post-operative vision loss (POVL)1
 Incidence: 1 in 500 spinal surgeries1
 4 Types of Vision Loss1
1.
2.
3.
4.
External Ocular Injury: Corneal abrasion, scleral injury
Cortical Blindness: 2° to vascular insults to visual tract/cortex
Central Retinal Artery Occlusion: direct pressure to globe
ION: posterior or anterior depending on location of lesion
 Occurred in ages 18-853
 No/few comorbidities3

23. Etiology
 Compromised blood flow to Optic Nerve leads to retinal ischemia
and vision loss2,3,5-7
 Increased IOP and/or decreased Mean Arterial Pressure
 Decreased perfusion to Optic Nerve
 Linked to anatomical modification of posterior ciliary artery
circulation7
 Edema/Excess Fluid Administration1
 Compromise tissue oxygenation from increase in tissue pressure in spaces
like the orbital cone1,8
 Slows microvascular perfusion = increase in Arterial venous shunting and
decrease in sympathetic draining
 Further increases edema
 Removal is by active sodium transport and maintenance of gradient
between hydrostatic and colloid osmotic pressure
 Small Optic Disc
 Mechanical obstruction and stasis may reduce axoplasmic flow

24. Treatment
 Hyperbaric Oxygen: increases arterial pressure and
hemoglobin8
 Blood Transfusions: corrects anemia and hypotension7,8
 Acetozolamide: decreases IOP and improves blood flow
to optic nerve and retina7,8
 Diuretics (Mannitol & Furosemide): decrease edema7,8
 Corticosteroids: decrease axonal swelling in acute
phase7
 However, increases risk for wound infection

25. Prognosis
 No known, established treatment improves visual outcome2,6
 Small improvement with retrobulblar steroid
injections, antiplatelet blood
replacement, therapy, anticoagulants, phenytoin, and
norepinephrine
 Immediate correction of anemia and hypotension was the only
proven valuable treatment7
 Irreversible, permanent vision loss7
 Vision loss can be temporary, but often severely debilitating3
 Very small improvement of visual outcome; very rare
complete visual recovery5
 Spontaneous recovery may occur, but improvement from
No Light Perception is rare6

26. How did this patient fare?
 Unfortunately, this patient was diagnosed too late after
surgery, so no treatment was available.
 5 days later: HM OD; sup field loss remained—however
ONH edema began to resolve
 2 weeks later: 20/400 OD; depressed superior field; ONH
edema completely resolved
 She is now enrolled in low vision services.

27. Risk Factors
Pre-op2,3,5,7
 Anemia
During Operation1-3,6,7
 Hypotension
 Hypotension <20mm Hg than
baseline
 Chronic Hypertension
 Duration of surgery >4-6 hrs6
 Diabetes
 Blood loss ~ 44.7%7
 Artherosclerosis
 Replacement Fluids
(excessive hydration)
 Smoking
 Obesity
 Anemia
 Hypercoaguable disease
 Prone Position (greatest risk6)
 Anatomical Structural factors of
the Optic Nerve
 Combination of the above

28. Current guidelines
 However, the Task Force of Perioperative Blindness4
 “does not believe that there are identifiable pre-operative
characteristics that predispose patients to perioperative
ION.”4
 “believes there is no evidence that an ophthalmic or neuroophthalmic evaluation would be useful in identifying at risk
patients.”
 “believes there is an increased risk for patients in prolonged
procedures, blood loss, and/or both.”
 High-risk patients should have fluids monitored, head level in
a neutral forward position, and vision assessed after waking
from anesthesia.
 If a visual problem is detected, urgent ophthalmic
consultation is recommended for the cause of vision loss

29. Recommendations1,2,5,7,8

High Risk Patient Recognition

Positioning: avoid prone position and changing head position, protecting the eyes

Hematocrit maintained

Mean Arterial Pressure maintained at baseline

Fluid Control (only treatment modality proven valuable)7

Staging

During Recovery1





Avoid flat positioning
Monitor blood pressure
Check pupils and Vision
Check for orbital edema and tension
After recovery: immediate evaluation of patients with new visual complaints

30. Future Implications
 Sharp increase in the annual number of spinal fusion
surgeries performed in the U.S.1,3
 From 1996 to 2004: 60,000 to 300,000
 A 500% increase
 The growing aging population leads to an increasing
incidence of chronic vascular disease
 Dramatic Rise = ominous increase in complications
 Recognizing and diagnosing peri-operative vision loss is
crucial because other etiologies may be treatable if
diagnosed early.6

31. Summary
 Due to low frequency, no prospective study exists identifying origin,
prevention, treatment.1
 Information has been extrapolated from retrospective reviews and
case reports.1
 The task force on Perioperative Blindness recommends aggressively
maintaining blood pressure & volume at baseline while keeping the
head level in a neutral position for high risk patients.
 However, there is no patient profile that identifies the high risk
patient for ION.7
 As the incidence of spinal surgeries increase, complications will
continue to rise, indicating the need for awareness of visual
complications among patients, eye care professionals, surgeons,
and anesthesiologists.

32. References
1.
Baig, Mirza N., Martin Lubow, Phillip Immesoete, Sergio D. Bergese, Elsayed-Awad Hamdy, and Ehud Mendel.
"Vision Loss after Spine Surgery: Review of the Literature and Recommendations." Neurosurgical FOCUS 23.5
(2007): E15. Print.
2.
Chang, Shu-Hong, and Neil R. Miller. "The Incidence of Vision Loss Due to Perioperative Ischemic Optic
Neuropathy Associated With Spine Surgery." Spine 30.11 (2005): 1299-302. Print.
3.
Kendrick, Heather. "Post-Operative Vision Loss (POVL) following Surgical Procedures." Journal of Anesthesia &
Clinical Research 3.184 (2012): n. pag. Print.
4.
Practice Advisory for perioperative visual loss associated with spine surgery: a report by the American Society of
Anesthesiologists Task Force on Perioperative Visual Loss. Anesthesiology. 2012 Feb; 116(2):274-85. Print.
5.
Myers, Mark A., MD, Steven R. Hamilton, MD, Armen J. Bogosian, MD, Craig H. Smith, MD, and Theodore A.
Wagner, MD. "Visual Loss as a Complication of Spine Surgery: A Review of 37 Cases." Spine 22.12 (1997): 1325-329.
Print.
6.
Ogilvie, James W., MD, and John Sanders, MBBS, FRCA. "Vision Loss following Surgery." AAOS Now (2009): n. pag.
Print.
7.
Pierce, Vickie, MNA, and Phillip Kendrick, CRNA, PhD. "Ischemic Optic Neuropathy After Spine Surgery." AANA
Journal 78.2 (2010): 141-45. Print.
8.
Roth, S. "Perioperative Visual Loss: What Do We Know, What Can We Do?" British Journal of Anaesthesia
103.Supplement 1 (2009): I31-40. Print.