Postoperative Visual Loss

1
Postoperative Visual Loss

• Marybeth A. Grazko MD

2
Postoperative Visual Loss

• Impairment or total loss of sight following an
  otherwise uncomplicated surgical anesthetic
  requiring procedure (non-ocular)
• Most commonly associated with spinal surgeries.
• Most common pathophysiology is posterior ischemic
  optic neuropathy (PION).

3
Postoperative Visual Loss

• Uncommon,devastating and poorly understood.
• Uncommon
• Most often associated with spinal, cardiac, head
  and neck surgeries. Incidence is spine surgery
  0.2 (50 fold higher incidence )
• Posterior ischemic optic neuropathy is by far the
  most common mechanism of permanent visual loss
• 83/93 cases reported in American Spine
  Association registry were due to ischemic optic
  neuropathy (ION),
• 53 P(posterior)ION, 19 A(anterior)ION, 10
  unspecified ION, 10 central retinal artery
  occlusion

4
Case 1

• 65 year old male underwent
• Cystocopy, bilateral ureteral stent placement
• Laparascopic bilateral pelvic lymph node
  dissection
• Laparscopic radical prostatectomy
• 16.5 hour procedure
• Trendelenburg dorso-lithotomy position for most
  of this time

5
Pre-Op History

• Past Ocular hx
• Retinal detachment repair
• Cataract
• Primary open angle glaucoma OS with glaucomatous
  optic neuropathy (had afferent pupillaryt defect
  OS pre-operatively)
• Humphrey 30-2 perimetry pre-operatively showed
• Normal OD
• Arcuate defect OS
• pre-operative visual acuity of 20/20 OD, 20/50 OS

6
Intra-operative Course

• After anesthetic induction blood pressure dropped
  to 80/50 for 30 minutes but otherwise maintained
  110-130 mmHg systolic and 70-80 mm Hg for the
  rest of the case
• Blood loss 500cc
• Post op HCT was 38.3
• No known operative or anesthetic complications

7
Post Op exam

• Patient complained of visual loss OD upon
  awakening
• Visual acuity 20/40 OD, 20/60 OS no afferent
  pupil defect!
• Mild punctate corneal erosions OD
• Significant facial and periorbital edema
• Dilated fundus exam was normal
• Humphrey perimetry OD peripheral depression
  extending to fixation superiorly. OS unchanged

8
(No Transcript)
9
Case 2

• 22 year old female
• Right laparoscopic pyeloplasty for right
  ureteropelvic junction obstruction
• 6 hour surgery
• Blood pressure 100/45 after induction, 100-110
  over 50-60 mm Hg for duration of the case
• Blood loss 50 cc
• Post op HCT 34.2
• Significant facial and periorbital edema

10
Post Operative status

• Immediately noted bilateral loss of vision but
  attributed it to the anesthesia
• Post-Op Day 7 Ophthalmology consult
• Visual acuity 20/20 OU
• Relative afferent pupil defect OS
• Humphrey perimetry peripheral depression OD,
  diffuse depression OS
• Brain and orbit MRI were normal

11
(No Transcript)
12
Post Operative Visual Loss

• Primary pathophysiology
• Anterior ischemic optic neuropathy
• Posterior ischemic optic neuropathy
• Central retinal artery occlusion
• Associated surgical procedures
• Cardiac, thoracic, cerebrovascular, abdominal,
  orthopedic, sinus and neck
• Majority of the cases are associated with spinal
  surgeries

13
Majority of perioperative visual loss has been
due to PION (50-71)

• Posterior Ischemic Optic Neuropathy
• Sudden painless loss of vision
• Unilateral or bilateral (may or may not have
  associated afferent pupillary defect)
• Normal fundus exam
• Nonspecific visual field abnormality
• In the absence of an afferent pupil defect may
  need negative neuroimaging to confirm the
  diagnosis

14
Delay in Diagnosis

• Often most of the bedside objective exam will be
  normal.
• Patients often may attribute changes in their
  vision to a recovery time following anesthesia.
• May have other post-operative issues that
  overshadow these symptoms.

15
Clinical Characteristics of PatientsBuono MB,
Forrozan R, Surv Ophthalmol 50 15-26, 2005Lee
et al, Anesthesiology 2006 105 652-9

• Age
• 51.9 average
• 43.9 spinal surgery, registry average was 50
• Degree of visual loss
• Count fingers or worse in 75.8
• No light perception in 53.8 (56.6)
• Bilateral involvement in 60.9 (66)
• Visual recovery
• Some visual recovery in 37.9 (42)
• Patients with poorer vision initially tended to
  have less improvement and poorer outcomes
• 54.9 had a final visual acuity of Hand motion or
  worse

16
Clinical Characteristics of PatientsBuono MB,
Forrozan R, Surv Ophthalmol 50 15-26, 2005

• No optic disc cupping noted
• Small congenital optic nerve head or absent
  phyiologic cupping noted only in 4 in one series
• 65.5 had one or more vascular risk factors
• 34.5 had no vascular risk factors

17
Clinical CharacteristicsLee et al,
Anesthesiology 2006 105 652-9

• Average anesthetic duration
• 9.8 h /- 3.1 hours
• 6 hours or longer in 94
• Estimated blood loss
• 82 was 1000 cc or greater
• Blood Pressure widely varied from less than 20
  of baseline to 50 of baseline or greater, HCT
  (hematocrit) also had wide variations between
  patients

18
Pathology

• PION results from infarction of the intraorbital
  portion of the optic nerve
• Infarction results due to decreased oxygen
  delivery presumably to any number of
  perioperative hemodynamic derrangements

19
PathophysiologyDecreased oxygenation leading to
infarction

• Decrease in perfusion pressure
• Hypotension (decreased Mean Arterial Pressure)
• Disturbed autoregulation (atherosclerosis,
  hypertension)
• Increase in intraocular pressure ( prone and head
  down positioning)
• Increase in Venous pressure
• Prolonged head down and prone position
• Internal jugular compression or ligation
• Decreased oxygen carrying ability
• Anemia
• Hemodilution

20
Hemodynamic derangements

• Hypotension and blood loss are common in cardiac
  bypass surgery. Low incidence of PVL seen in
  cardiac bypass patients suggests that another
  mechanism is playing an additional role in the
  mechanism for permanent visual loss.
• Anatomic variation in blood supply of
  intraorbital nerve (absent anastomoses)
• Positioning creating either increased intraocular
  pressure and/or increased orbital venous pressure

21
From Ozcan Anesth Analg, Volume 99 (4), Oct
2004. 1152-1158
22
Blood Supply of the Nerve
23
Facial Edema

• Facial edema
• Often data was not provided but in 19 patients
  where this was commented upon, 17/19 had post
  operative facial edema and in 11 was considered
  to be severe. (both of our cases had severe
  facial edema)
• Evidence that positioning can increase
  intraocular pressure (maximal in Trendelenberg)
• Increased intraocular pressure can lead to
  decreased perfusion.

24
Pathogenesis

• Hemodynamic derangement
• Evidence to date points to prolonged surgery,
  blood loss or combination of both
• In a patient with a specific susceptibility which
  at this point remains unclear
• Incomplete anastomoses, altered anatomy
• Risks factors of positioning and
  periorbital/facial edema may contribute but at
  this point are less clearly factors

25
Recent Practice AdvisoryAm Soc of
Anesthesiologists

• Spine procedure
• Positioned prone
• Receiving general anesthesia
• Uncommon occurrence
• Less than 0.2 of spine surgeries
• Makes it a difficult thing to study, mostly case
  control studies and case reports in terms of what
  is in the literature.

26
ASA Practice Advisory

• Task force of 12 members
• 4 Anesthesiologists
• 3 Neuro-Ophthalmologists
• 1 Orthopedic Spine Surgeon
• 1 Neurosurgeon
• 2 Methodologists from ASA Practice Parameters
  committee
• 3 physicians served as liasons from national
  organizations
• NANOS
• Am Academy of Orthopedic Surgeons
• Am Association of Neurologic Surgeons
• Opinions were also solicited from Society for
  Neurosurgical Anesthesia and Critical Care,
  NANOS, and North American Spine Society
• Summary of the available literature, expert
  opinion, open forum commentary and consensus
  surveys

27
Predictive Risk Factors

• Vascular risk factors (hypertension, diabetes,
  smoking,obesity,glaucoma, carotid artery disease)
• Pre-operative presence of anemia
• Prolonged procedures (range was 2-12 with average
  of 6.5 hours)
• Substantial blood loss (ranges was 10-200 with
  average of 44.7 of total blood volume)

28
Pre-Operative Assessment

• Task Force was in consensus that
• There is no evidence that an ophthalmic or
  neuro-ophthalmic exam pre-operatively is useful
  for identifying patients at risk
• Recommendation was to consider informing patients
  in whom prolonged procedures, substantial blood
  loss or both are anticipated that there is a
  small unpredictable risk of perioperative visual
  loss.

29
BP,fluid,blood loss managment

• Recommend continual monitoring in high risk
  patients (CVP monitoring)
• Deliberate hypotensive techniques have not been
  shown to be associated with peri-operative visual
  loss.
• There is no absolute hematocrit number to use a
  transfusion threshold, individually dependent

30
Patient Positioning

• Several case reports of direct pressure to the
  eyes from use of a sheet roll or head rest
  resulting in central retinal artery occlusion
  (CRAO) or ION but also in patients with no
  headrest (head held by pins)
• All task force members agreed that direct
  pressure on the eye should be avoided to reduce
  risk of CRAO and other ocular damage.

31
Head positioning?

• No pathophysiologic mechanism by which facial
  edema can cause perioperative ION
• Eyes of prone patients should be regularly
  checked
• Peri-operative facial edema is common in high
  risk patients
• Postion the head level or higher than the heart
  for high-risk patients
• Keep the head in a neutral forward position when
  possible
• Direct pressure on the eye should be avoided to
  avoid CRAO

32
Treatment

• Correction of hemodynamic derangements, systemic
  steroids, antiplatelet therapy, measures to lower
  intraocular pressure or intracranial pressure.
• None effective though a few case reports of
  improvement with transfusion and keeping blood
  pressure over 140/80

33
Peri-operative Visual loss registry

• http//depts.washington.edu/asaccp/eye/index.shtml
  
• www.asaclosedclaims.org
• Established in 1999
• Recently published on 93 spine cases (93/131
  cases 72)
• Lee et al Anesthesiology 2006, 205652-659.
• Anonymous reporting

34
(No Transcript)
35
Advisory

• PION can be seen with a variety of surgical
  procedures but is more likely to be seen with
  spinal procedures
• There is no evidence that compression is a factor
  in the pathophysiology of this entity although
  compression is clearly related to CRAO
• PION does correlate with prolonged surgery (gt 6
  hours)

36
Advisory

• While PION does correlate with blood loss, the
  amount of blood loss required is unclear and can
  still occur in the absence of significant blood
  loss as our cases demonstrate.
• PION is somewhat more likely with prolonged
  hypotension but again the range where this is
  significant is likely to be very patient
  dependant.

37
Advisory

• Patients in a prolonged supine position with
  significant peri-orbital swelling (our two cases)
  while theoretically this could predispose them to
  PION has yet to be recognized as an independent
  risk factor.

38
Prognosis

• Visual recovery
• Some visual recovery in 37.9 (42)
• Patients with poorer vision initially tended to
  have less improvement and poorer outcomes
• 54.9 had a final visual acuity of HM or worse
• Both of our patients had some improvement both in
  their acuity and visual fields but again were
  more mildly affected than many of the other
  reported cases

39
Summary

• Postoperative Visual Loss is a fortunately rare
  but devastating condition that is still poorly
  understood.
• Recent reports by the ASA Registry and reviews of
  the literature would suggest counseling patients
  who are undergoing procedures that are prolonged
  and/or with expected substantial blood loss about
  the potential risk for this condition.