POSTOPERATIVE VISION LOSS (POVL)

PRESENTED BY :DR.ANKITA MADAN

Partial or complete vision loss of vision occuring after general anaesthesia for nonocular surgery.

Uncommon complication

Associated more with cardiac surgery or procedures on the spine done in prone position.

PATHOPHYSIOLOGY Ischemia to visual pathway particulary the

optic nerve and the retina.

Major source of blood supply of retina and optic nerve is the Opthalmic artery branch of internal carotid artery.

Branches : Central retinal artery and long and short posterior arteries – blood supply of retina

Posterior portion of optic nerve more susceptible to poor perfusion in presence of hypotension due to comparatively less vascular supply.

CAUSES OF POVL Ischemic optic neuropathy (ION)

Central retinal artery occlusion (CRAO)

Cortical blindness

Posterior reversible encephalopathy syndrome (PRES)

VISION LOSS AFTER SPINAL SURGERY Anterior ischemic optic neuropathy

Posterior ischemic optic neuropathy

Retinal vascular occlusion

ISCHEMIC OPTIC NEUROPATHY(ION) Irreversible painless loss of vision

Spontaneously without any warning signs

Usually seen after cardiac surgery , spine surgery , head and neck surgery , orthopedic joint procedures and surgery on nose or sinuses.

Two types - anterior or posterior ION

AION –Most commonly after cardiac surgery

PION –After spine surgery in prone postion or radical neck dissection.

MECHANISM FOR ION Increased venous pressure in the globe and

interstitial edema during prone position

Increase in intraocular pressure

Compression of vessels supplying optic nerve

Hypoxia of optic nerve

RETINAL ISCHAEMIA CENTRAL RETINAL ARTERY OCCLUSION

decreases blood supply to the entire retina

BRANCH RETINAL ARTERY OCCLUSION affects only a portion of the retina.

Following ocular trauma , embolic phenomenon following carotid surgery and vasospastic episodes.

In spine surgery , it is due improper patient positioning and external compression of eye.

POVL AFTER CARDIAC SURGERY Risk factors :

Lower postoperative haematocrit

Presence of clinically significant vascular diseae

Long duration of CPB

Red cell transfusions

Use of other blood components

POVL AFTER HEAD AND NECK SURGERY ION after neck dissection

CRAO after neck and nasal or sinus surgery

Orbital hemorrhage from blunt trauma during the procedure

PERIOPERATIVE VISUAL LOSS IN OTHER SURGERIES After robotic and laparoscopic surgeries

especially after laparoscopic nephrectomies and robotic prostatectomies.

During robotic prostatectomy, patient in steep trendelenburg position for a prolonged time and co2 insufflation of the abdomen increases the CVP , the intrathoracic pressure and the intraocular pressure.

OTHER CAUSES OF POVLCORTICAL BLINDNESS Result of decreased perfusion to the occipital cortex

due to hypoperfusion and embolic phenomenon.

Normal light reflex and fundoscopic examination.

Prevention by maintaining normal perfusion pressure and hematocrit of about 30%.

POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME (PRES)

SEIZURES

HEADACHE

VOMITING

VISION DEFECTS

DECREASED LEVEL OF CONSCIOUSNESS.

Reported after severe hypertension , chemotherapy , immune suppression , renal disease , vasculitis and eclampsia , lumbar spine fusion , hysterectomy and video assisted thoracoscopic surgery .

Treatment is symptomatic.

ASA PRACTICE ADVISORY Inform patients undergoing spine surgery of long

duration and expected excessive blood lossabout small and unpredictable risk of POVL.

Systemic BP to be monitored in high risk patients. Deliberate hypotension should be practiced on case by case basis.

Central venous pressure must be monitored in high risk patients.

To maintain hematocrit of above 28%

Use of vasopressors on case by case basis.

During positioning , direct compression on eyes must be avoided and head should be maitained in neutral position at the level or higher than the level of heart.

Staging of surgical procedure must be given consideration in high risk patients.

Vision must be tested of high risk patients for POVL immediately after they are awake and ophthalmology opinion must be taken urgently if there is any concern.

Optimization of Hb level , hemodynamic status and oxygenation may be addressed

THANKS