blindness following a le fort i osteotomy , though rare , is an extremely serious complication . ( laniganet al . , bendor - samuel et al . , girotto et al . , wilson et al . , lo et al . , cruz et al . , cheng et al . ) . these include : lachrymal gland injuries ; cranial nerve iii , iv and vi palsies ; traumatic aneurysms ; and arteriovenous fistulae ( lanigan et al . , girotto et al . , cruz et al . , steel and cope ) it is generally agreed that optic neuropathy is the mechanism that leads to loss of vision in a le fort i osteotomy , but exactly how this occurs in an elective surgery is a question of debate . direct injury to the nerve from atypical fractures of the base of skull or orbital walls has been found to account for only 3 of the 10 reported cases in the literature ( lanigan et al . , bendor - samuel et al . , cruz et al . ) , while indirect trauma to the optic nerve or its blood supply has been considered in the other 7 cases ( lanigan et al . we report the first 2 documented cases of complete loss of vision that was restored , following le fort i osteotomies . the reported cases were in cleft patients and were presumably straightforward cases with no untoward difficulties intraoperatively . in one case , full vision was regained , while near - complete vision has been recovered in the second , more recent case . a 19-year - old male with bilateral cleft lip and palate presented to the centre in february 2006 for correction of his maxillary regression . a le fort i osteotomy with advancement was performed under controlled hypotensive anaesthesia with the mean arterial pressure maintained at about 70 mmhg . the osteotomy , pterygoid dysjunction and down - fracture of the maxilla were done without any difficulty . the estimated blood loss for the procedure was 500 ml and the duration of surgery was 90 min . on the second postoperative day , the patient complained of loss of vision in the right eye . on examination , there was no perception of light in the right eye , while the visual acuity for the left eye was 6/6 . the patient was immediately started on intravenous methylprednisolone 500 mg , twice daily . meanwhile , an emergent computed tomography ( ct ) scan of the orbits , base of skull and brain , and doppler study of the carotid and vertebral arteries were done . except for opacities seen in all the paranasal sinuses suggestive of haemorrhage and the left pterygoid separation that had occurred anterior to the pterygomaxillary fissure , the ct scans were normal . the doppler study of the carotid and vertebral arteries was also normal [ figure 1a and b ] . ( a and b ) coronal section of the first patient showing blood in the spheno - ethmoidal and maxillary sinuses ( c ) sagittal section of the first patient showing intact optic canal the patient 's vision in the right eye began to improve gradually from hand movements on the 11 postoperative day , to a visual acuity of 6/9 by 1 month postoperatively . fundus examination later showed disc pallor in the right eye , with normal findings in the left eye . several months postoperatively , 6/6 vision was reported for the right eye and has remained so , to date . a 22-year - old male patient with unilateral cleft lip and palate presented with maxillary regression . the procedure was uneventful and the pterygoid dysjunction and down - fracture were done without any difficulty . controlled hypotensive anaesthesia was given for less than 20 min , with the mean arterial pressure maintained at 70 mmhg . the duration of surgery was 45 min and the estimated blood loss was approximately 700 ml . postoperatively in the recovery room , he complained of complete loss of vision in the left eye . eye examination revealed defective vision in the left eye , while the right eye was normal . ct scans showed no atypical fractures to the base of skull or orbits , but showed opacities in the spheno - ethmoidal air cells . ( a and b ) coronal section showing blood in the spheno - ethmoidal and maxillary sinuses of the second patient ( c ) sagittal section of second patient showing intact optic canal the patient 's left eye vision improved gradually , with a visual acuity of 1/60 on the 6 postoperative day to 4/60 by 4 months postoperatively . disc pallor of the left eye was noted on fundoscopy 1 month postoperatively , and a diagnosis of ischaemic optic neuropathy was made . a 19-year - old male with bilateral cleft lip and palate presented to the centre in february 2006 for correction of his maxillary regression . a le fort i osteotomy with advancement was performed under controlled hypotensive anaesthesia with the mean arterial pressure maintained at about 70 mmhg . the osteotomy , pterygoid dysjunction and down - fracture of the maxilla were done without any difficulty . the estimated blood loss for the procedure was 500 ml and the duration of surgery was 90 min . on the second postoperative day , the patient complained of loss of vision in the right eye . on examination , there was no perception of light in the right eye , while the visual acuity for the left eye was 6/6 . the patient was immediately started on intravenous methylprednisolone 500 mg , twice daily . meanwhile , an emergent computed tomography ( ct ) scan of the orbits , base of skull and brain , and doppler study of the carotid and vertebral arteries were done . except for opacities seen in all the paranasal sinuses suggestive of haemorrhage and the left pterygoid separation that had occurred anterior to the pterygomaxillary fissure , the ct scans were normal . the doppler study of the carotid and vertebral arteries was also normal [ figure 1a and b ] . ( a and b ) coronal section of the first patient showing blood in the spheno - ethmoidal and maxillary sinuses ( c ) sagittal section of the first patient showing intact optic canal the patient 's vision in the right eye began to improve gradually from hand movements on the 11 postoperative day , to a visual acuity of 6/9 by 1 month postoperatively . fundus examination later showed disc pallor in the right eye , with normal findings in the left eye . several months postoperatively , 6/6 vision was reported for the right eye and has remained so , to date . a 22-year - old male patient with unilateral cleft lip and palate presented with maxillary regression . the procedure was uneventful and the pterygoid dysjunction and down - fracture were done without any difficulty . controlled hypotensive anaesthesia was given for less than 20 min , with the mean arterial pressure maintained at 70 mmhg . the duration of surgery was 45 min and the estimated blood loss was approximately 700 ml . postoperatively in the recovery room , he complained of complete loss of vision in the left eye . eye examination revealed defective vision in the left eye , while the right eye was normal . ct scans showed no atypical fractures to the base of skull or orbits , but showed opacities in the spheno - ethmoidal air cells . ( a and b ) coronal section showing blood in the spheno - ethmoidal and maxillary sinuses of the second patient ( c ) sagittal section of second patient showing intact optic canal the patient 's left eye vision improved gradually , with a visual acuity of 1/60 on the 6 postoperative day to 4/60 by 4 months postoperatively . disc pallor of the left eye was noted on fundoscopy 1 month postoperatively , and a diagnosis of ischaemic optic neuropathy was made . the complication of blindness following an elective surgery is indeed devastating to both the patient and the surgeon , especially when one can not explain to the patient exactly how it has occurred . we report 2 cases of blindness out of 690 le fort i surgeries done from 1996 to 2012 by the same surgeon , for an overall incidence of 0.29% . reported an incidence of 0.25% in a survey of north american oral and maxillofacial surgeons , while lo et al . reported an incidence of 2.1% for a centre in taiwan . in the 7 cases in literature , and in our 2 , where unfavourable fractures are absent , adverse transmission of forces to the base of skull during pterygoid separation and downfracture has been proposed as the mechanism of injury ( cruz et al . transmitted forces have been postulated to cause contusion or contrecoup type injuries to the nerve or compression of the nerve from haemorrhage and/or oedema around the optic canal , causing ischaemia of the nerve . it has also been considered that hypoperfusion of the optic nerve due to the controlled systemic hypotension might have a significant role in causing blindness ( lanigan et al . injury to the ophthalmic artery from transmitted forces could be responsible for the haemorrhage within the spheno - ethmoidal sinuses in the ct scans of both our cases . the resultant hypoperfusion to the nerve , made worse by the hypotensive anaesthesia , may have caused the ischaemic optic neuropathy that led to unilateral loss of vision . we believe that loss of vision occurred unilaterally because the forces transmitted to the nerves and therefore the degree of injury inflicted on the nerves was unequal , as evidenced by the fracture pattern seen following both our osteotomies . the fractures had occurred anterior to the pterygomaxillary fissure , type f separation ( ueki et al . ) , on the opposite side of the affected nerves . lanigan et al . , stated that evidence of spheno - ethmoidal sinus haemorrhage should make one suspicious of the possibility of optic nerve injury , though they did not elucidate on the mechanism of injury . we believe that the optic nerve and the ophthalmic artery suffer some degree of injury following this elective surgery due to their proximity to the surgical site . however , from our 2 cases , it appears that the nerve can recover from this insult , as long as it is not exposed to additional and prolonged ischaemic injury from controlled systemic hypotensive anaesthesia . fortunately for our 2 cases , the duration of hypotensive anaesthesia was short and this was perhaps the reason the blindness was reversible . lanigan et al . , reported a case of blindness where the patient had been on hypotensive anaesthesia for 3 h ; lo et al . reported that both their cases had been under hypotensive anaesthesia for 75 min and 95 min ; and wilson et al . , though they did not mention the duration of hypotensive anaesthesia , had a 14-h surgery with a lowest recorded blood pressure ( bp ) of 80/40 . cheng et al . , also reported a case of blindness where hypotensive anaesthesia had been used for 8 h. all these patients suffered irreversible blindness . controlled hypotensive anaesthesia in isolation does not cause blindness ; it seems to aggravate the insult to an already injured nerve . ( 2004 ) , who reported a case of blindness following spinal surgery due to compression of the globe by the head rest in the prone position . cheng et al . also reported a case of blindness where the effects of a hypoplastic carotid artery may have been made worse by hypotensive anaesthesia following le fort osteotomy . it has also been shown from animal studies that the optic nerve will not recover from ischaemia of over 60 min ( yoon and marmor , tsukahara et al . ) . the duration of tolerable ischaemia to the optic nerve is quite possibly much lower in humans . we therefore strongly recommend that hypotensive anaesthesia be avoided for this procedure or , if used at all , be used for a very short period of time . proper surgical technique should also be employed to avoid unfavourable fractures and excessive haemorrhage , hence circumventing the need for hypotensive anaesthesia . it is also suggested that all patients undergoing le fort osteotomies undergo a preoperative ophthalmic assessment of vision .
blindness following a lefort i osteotomy is a rare but extremely serious complication . 
 ten cases have been reported to date . 
 none of these patients recovered vision . 
 optic neuropathy is believed to be the cause but the exact mechanism has not been settled . 
 we report the first , and the only two , documented cases of complete loss of vision that recovered subsequently . 
 the first patient was a 19-year - old male with repaired bilateral cleft lip and palate . 
 he developed loss of vision in the right eye on the second postoperative day . 
 the second patient was a 22-year - old male with repaired unilateral cleft lip and palate . 
 he developed complete loss of vision in the left eye on the day of surgery . 
 both these patients underwent ongoing studies , which did not show any abnormalities . 
 both were treated with methylprednisolone . 
 both the patients gradually showed improvement in their vision . 
 the first patient recovered normal vision several months postoperatively . 
 the second patient 's vision improved to 4/60 by 4 months postoperatively . 
 we discuss the probable mechanisms of optic nerve injury and also the possible reasons why sight was restored in these patients . 
 this is a rare but serious complication following a fairly common procedure . through this article 
 we wish to create an awareness of this complication and also a possible way of avoiding such a disaster .