Postoperative Visual Loss Research Articles

Central 10-degree visual field change following non-penetrating deep sclerectomy in severe and end-stage glaucoma: preliminary results.

To report the impact of non-penetrating deep sclerectomy (NPDS) in severe and end-stage glaucoma treatment on the central 10° visual field progression (mean deviation, four central points, foveal threshold) and assess the risk of sudden visual loss. Monocenter database study. We reviewed records of 34 eyes with severe or end-stage glaucoma that underwent NPDS between 2009 and 2015, at the National Ophthalmology Center of XV-XX (Paris, France). Severe and end-stage glaucoma were defined according to the Bascom Palmer Modified Glaucoma Staging System classification. All eyes had a constricted visual field < 10° (severe injury by the Humphrey visual field automated (HVFA) 10-2). Visual fields were recorded every 6months after the procedure. Data from the last visit was used for the statistical analysis. The mean follow-up duration was 29months (range 6 to 54) and 33 (97%) eyes were followed for more than 1year. There were no cases of postoperative sudden visual loss. The intraocular pressure (IOP) decreased from 21.9 ± 8.1 to 15.0±5.4mmHg (P < .001). Twenty-eight (82%) eyes had an IOP < 21mmHg and 19 (56%) an IOP < 16mmHg. The MD 10-2 remained stable (- 19.8±7.4 to - 19.4±8.1dB, non-significant improvement of + 0.4dB, P = .1). The MD 10-2 slope showed an insignificant improvement of + 0.25±1.8dB per year (dB/y) (P = 0.1), but this slope was significantly better when the IOP was reduced to < 16mmHg than when the IOP was ≥ 16mmHg at the last visit (+ 0.841.2 versus - 0.48±2.2dB/y, P = .05). The mean number of the four central test points with sensitivity ≤ 5dB and the change in mean sensitivity of the four central field points remained stable. There were no significant changes in the VFI (from 25.4% ±13 to 25.8% ±20) and in foveal threshold. NPDS appears to provide stability of the central 10° visual field (with a trend towards improvement but non-significant) with no occurrence of "wipe-out" phenomenon and few other complications. Consideration of NPDS in end-stage and severe glaucoma is advisable given its low risk of complications and its considerable IOP decrease with a relative stability of the central visual field.

Lamellar macular holes: surgical outcome of 106 patients with long-term follow-up.

To determine long-term results of vitrectomy for lamellar macular holes(LMH). To evaluate how the type of lamellar macular hole (tractional vs. degenerative) and the crystalline lens status might influence visual outcomes. We collected data from 106 patients with symptomatic lamellar macular hole that underwent pars plana vitrectomy with membranectomy and internal limiting membrane peeling. Best-corrected visual acuity(BCVA) and optical coherence tomography appearance were determined preoperatively and postoperatively. Most of the lamellar holes were of tractional type (65%). Mean follow-up after surgery was 36months. Mean BCVA increased from 20/50 to 20/43 at 6months and 20/33 at last follow-up visit (p< 0.001). Vision improved in 74 (70%), remained stable in 11 (10%), and decreased in 21 (20%) eyes. Subgroup analysis showed that visual acuity significantly increased in the tractional but not in the degenerative forms of LMH. Thirteen eyes lost two or more ETDRS lines after surgery. Preoperative phakic/pseudophakic status influenced the functional outcomes. Surgery may be effective in some subsets of patients with lamellar macular hole, but postoperative visual loss is not uncommon and prospective controlled studies are warranted.

Physiology and Role of Intraocular Pressure in Contemporary Anesthesia.

More than 26 million Americans suffer with cataracts, and with 3.6 million cataract extractions performed annually in the United States, it is the most common surgical procedure. The integrity of the delicate structures of the eye that mediate vision is dependent on the intraocular pressure (IOP). Yet, IOP acts to compress the vessels within the globe-akin to a Starling resistor-and is a key component that determines the ocular perfusion pressure, defined as the difference between arterial pressure and IOP. The retina is one of the most metabolically active tissues in the body, and its functional integrity is dependent on an adequate blood supply, with retinal function linearly related to the ocular perfusion pressure. Retinal cell death has been demonstrated at low perfusion pressures (below 50 mm Hg). Modern ophthalmic surgery involves globe irrigation, manipulation, and instrumentation, resulting in dynamic pressure fluxes within the eye. Marked elevations of IOP (up to 4-5 times the normal value) with consequent borderline retinal and optic disk perfusion pressures occur for prolonged periods during many ophthalmic procedures. General surgeries, including laparoscopic, spinal, and cardiac procedures, especially, with their demand for steep Trendelenburg or prolonged prone positioning and/or hypotensive anesthesia, can induce IOP changes and ocular perfusion imbalance. These rapid fluctuations in IOP, and so in perfusion, play a role in the pathogenesis of the visual field defects and associated ocular morbidity that frequently complicate otherwise uneventful surgeries. The exact etiology of such outcomes is multifactorial, but ocular hypoperfusion plays a significant and frequently avoidable role. Those with preexisting compromised ocular blood flow are especially vulnerable to intraoperative ischemia, including those with hypertension, diabetes, atherosclerosis, or glaucoma. However, overly aggressive management of arterial pressure and IOP may not be possible given a patient's comorbidity status, and it potentially exposes the patient to risk of catastrophic choroidal hemorrhage. Anesthetic management significantly influences the pressure changes in the eye throughout the perioperative period. Strategies to safeguard retinal perfusion, reduce the ischemic risk, and minimize the potential for expulsive bleeding must be central to the anesthetic techniques selected. This review outlines: important physiological principles; ophthalmic and general procedures most likely to develop damaging IOP levels and their causative factors; the effect of anesthetic agents and techniques on IOP; recent scientific evidence highlighting the significance of perfusion changes during surgery; and key aspects of postoperative visual loss and management approaches for high-risk patients presenting for surgery.

PD38-05 PROSPECTIVE EVALUATION OF EFFECT ON INTRAOCULAR PRESSURE AND VISUAL FUNCTION IN PATIENTS WITHOUT AND WITH OPHTHALMIC DISEASES AFTER ROBOTIC ASSISTED LAPAROSCOPIC PROSTATECTOMY

You have accessJournal of UrologyProstate Cancer: Localized: Surgical Therapy V1 Apr 2018PD38-05 PROSPECTIVE EVALUATION OF EFFECT ON INTRAOCULAR PRESSURE AND VISUAL FUNCTION IN PATIENTS WITHOUT AND WITH OPHTHALMIC DISEASES AFTER ROBOTIC ASSISTED LAPAROSCOPIC PROSTATECTOMY SHIGENORI KAKUTANI, HIROSHI FUKUHARA, FUMIYUKI ARAKI, MASAAKI ASAMOTO, NOBUKO ITO, MAKOTO AIHARA, and HARUKI KUME SHIGENORI KAKUTANISHIGENORI KAKUTANI More articles by this author , HIROSHI FUKUHARAHIROSHI FUKUHARA More articles by this author , FUMIYUKI ARAKIFUMIYUKI ARAKI More articles by this author , MASAAKI ASAMOTOMASAAKI ASAMOTO More articles by this author , NOBUKO ITONOBUKO ITO More articles by this author , MAKOTO AIHARAMAKOTO AIHARA More articles by this author , and HARUKI KUMEHARUKI KUME More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1752AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Although the fact is well-known that Trendelenburg position increases intraocular pressure (IOP) during robotic surgery and might cause postoperative visual loss (POVL), very few papers have reported on effect in patients with ophthalmic diseases after robotic surgery. Taketani Y et al reported that transient but significant unilateral visual field defects were found in 28% subjects after robotic assisted laparoscopic prostatectomy (RALP). We prospectively evaluated the effect on IOP and visual function in patients undergoing RALP. METHODS In this clinical study, the enrolled patients were performed RALP uneventfully under general anesthesia from December in 2015 to March in 2017 in our single institution, The University of Tokyo Hospital. We measured IOP of both eyes before, during and 7days after RALP and performed visual field tests using Humphrey visual field analyzer (HFA) before, 7days after, and 1-3 months after RALP. RESULTS A total of 99 patients were analyzed; mean IOP before and during RALP were 11.5±4.2 mmHg and 22.4±3.6 mmHg, respectively. IOP was significantly increased during RALP with P value < 0.01 as previously reported. POVL in 7 days after RALP was detected in 21 eyes of 16 subjects but all of them recovered to normal in 1 month after RALP. Among of them, 4 eyes of 3 subjects were diagnosed as ophthalmic diseases before RALP; 2 eyes of 1 subject as normal tension glaucoma, 1 eye of 1 subject as epiretinal membrane and 1 eye of 1 subject as scleritis. Before RALP, 24 eyes of 15 subjects were diagnosed as glaucoma; 22 eyes of 14 subjects as normal tension glaucoma and 2 eyes of 1 subject as closed angle glaucoma, in whom laser iridectomy was performed before RALP and no POVL was detected after RALP. CONCLUSIONS In our study, although transient POVL was detected in 16% of subjects after RALP, no severe visual defects were detected in 1-3 months after RALP both in patients without and in patients with ophthalmic diseases. Our data suggests that RALP does not affect visual function in the long term after surgery even in patients with normal tension glaucoma. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e737-e738 Advertisement Copyright & Permissions© 2018MetricsAuthor Information SHIGENORI KAKUTANI More articles by this author HIROSHI FUKUHARA More articles by this author FUMIYUKI ARAKI More articles by this author MASAAKI ASAMOTO More articles by this author NOBUKO ITO More articles by this author MAKOTO AIHARA More articles by this author HARUKI KUME More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Incidence, Risk Factors, and Management of Blindness after Orbital Surgery

Severe vision loss is a risk of orbital surgery which physicians should counsel patients about, but the overall risk rate is unknown. This research was conducted to determine the risk of severe vision loss related to orbital surgery. Retrospective review. Patients who underwent orbital surgery at either of 2 academic medical centers between January 1994 and December2014. A billing database search was conducted to identify all patients who had orbital surgery during the study period, cross-checked against diagnostic codes related to vision loss. Charts were screened to determine baseline demographic and medical history, surgical procedure, intraoperative and perioperative management, and visual acuity. Patients with preoperative visual acuity ≥20/200 that worsened ≤20/400 after orbital surgery were included for detailed review. Statistical analysis was conducted to identify factors posing particular risk or benefit to visual outcome in these patients. Visual acuity after orbital surgery. A total of 1665 patients underwent orbital surgery during the inclusion period, with 14 patients sustaining severe vision loss ranging from counting fingers at 1 foot to no light perception (overall risk, 0.84%). The causes of vision loss included retrobulbar hemorrhage, malpositioned implant, optic nerve ischemia, or direct optic nerve insult. When stratified by surgical approach, the risk of a blinding surgical complication was significantly higher for patients undergoing orbital floor repair in the setting of multiple facial fractures (subgroup risk, 6.45%), bony decompression of the optic canal (subgroup risk, 15.6%), or intracranial approach to the orbital roof (subgroup risk, 18.2%). Seven of 8 patients with a potentially reversible cause of postoperative vision loss underwent urgent repeat surgery, and 2 regained substantial vision (20/20 and 20/25). Administration of intravenous corticosteroids had no significant effect on visual acuity outcome. The overall risk of severe vision loss after orbital surgery is 0.84%. The subgroup risk is higher in patients undergoing facial polytrauma repair, optic canal decompression, or orbital apex surgery from an intracranial approach. Close postoperative monitoring and urgent assessment and management of acute vision loss may improve visual outcome in some patients.

A Survey of Incidence of Postoperative Visual Loss Associated With Spine Surgery Outside the United States.

A Survey of Incidence of Postoperative Visual Loss Associated With Spine Surgery Outside the United States.

Postoperative Transient Blindness After General Anesthesia and Surgery: Case Report of Conversion Disorder

Postoperative acute visual loss due to organic pathology has been described after spinal surgery in the prone position. This report describes a case of transient postoperative blindness in a patient after general anesthesia and surgery in the prone position. Postoperative workup did not reveal any organic pathology. Unbeknown to the treating physicians, the patient had a comorbid untreated psychiatric history. Upon psychiatric consultation, the patient was diagnosed with conversion disorder as a cause of postoperative blindness. There was full recovery of vision after psychiatric intervention within a week.

Visual loss due to optic nerve infarction and central retinal artery occlusion after spine surgery in the prone position: A case report.

Rationale:Visual loss after spine surgery in the prone position is a serious complication. Several cases of central retinal artery occlusion with ophthalmoplegia after spine surgery have been reported in patients with ophthalmic arteries fed by the internal carotid artery (ICA) in a normal manner.Patient concerns:A 74-year-old man developed visual loss after undergoing a spinal decompression and fusion operation in the prone position that lasted approximately 5 hours.Diagnoses:We detected an extremely rare case of visual loss due to optic nerve infarction and central retinal artery occlusion through fundoscopic examination, fluorescein angiogram, brain magnetic resonance imaging, and magnetic resonance angiography. The patient's visual loss may have been caused by compromised retrograde collateral circulation of the ophthalmic artery from branches of the external carotid artery in the presence of proximal ICA occlusion after a spinal operation in the prone position.Interventions:To recover movement of the left extraocular muscles, the patient received intravenous injections of methylprednisolone for 3 days and then oral prednisolone for 6 days.Outcomes:Twenty days after the treatment, the motion of the left extraocular muscles was significantly improved. However, recovery from the left visual loss did not occur until 4 months after the operation.Lessons:In high-risk patients with retrograde collateral circulation of the ophthalmic artery from the external carotid artery due to proximal ICA occlusion, various measures, including the use of a head fixator to provide a position completely free of direct compression of the head and face, should be considered to decrease the risk of postoperative visual loss.

Advances of postoperative visual loss after spinal surgery with prone position

Background Postoperative visual loss(POVL) after spine surgery performed with prone position is a rare but devastating postoperative complication. Patients have poor prognosis. This complication has been highly concerned by anesthesiology and its related subjects in recent years. Objective This paper reviews advances in researches on POVL after spinal surgery with prone position. Content The clinical profile, etiology and prevention measures of POVL after spinal surgery with prone position are introduced. Trend Further understanding the etiology of the POVL will help reduce postoperative ophthalmic complications after spinal surgery with prone position. Key words: Postoperative visual loss; Spinal surgery; Prone position

Revisiting Postoperative Vision Loss following Non-Ocular Surgery: A Short Review of Etiology and Legal Considerations.

Postoperative vision loss (POVL) following non-ocular surgery is a serious complication where the causes are not fully understood. Studies have identified several causes of POVL as well as risk factors and prevention strategies. POVL research is made difficult by the fact that cases are often subject to malpractice claims, resulting in a lack of public access to case reports. This literature review was conducted in order to identify legal issues as a major barrier to studying POVL and address how this affects current knowledge. Informed consent provides an opportunity to overcome legal challenges by reducing malpractice litigation through educating the patient on this outcome. Providing pertinent information regarding POVL during the informed consent process has potential to reduce malpractice claims and increase available clinical information.

Transient Symptomatic Bilateral Optic Disc Oedema Following Lumbar Spinal Surgery— An Unusual Presentation

Background: Optic disc oedema has various underlying pathologies, however, unless visually disabling does not usually bring a patient to the physician. The more common symptoms of headache, nausea and vomiting lead to the incidental detection of bilateral disc oedema [1]. Optic disc oedema seen following spinal surgery is usually associated with visual acuity changes and often goes by the acronym POVL (Peri/ postoperative visual loss) wherein, as the name goes, visual acuity changes are profound [2] [3] [4]. Purpose: We would like to highlight a case of transient Bilateral Optic Disc oedema following Lumbar spinal surgery maintaining normal visual acuity and attaining spontaneous resolution. Case Report: A 42-year-old female presented with transient obscuration of vision and flashes of light post an uneventful lumbar spinal surgery. Ophthalmic evaluation revealed normal visual acuity and pupils but marked disc edema right more significant than left. There was no colour vision deficit, neither any field changes. By a process of exclusion, it was likely the patient had developed bilateral disc oedema secondary to the spinal surgery. On follow-up 6 weeks and 3 months later, the oedema had completely settled and visual acuity remained at 6/6. Conclusion: Optic disc oedema can be unilateral or bilateral with some of the uncommon conditions mentioned secondary to spinal surgery, however, in those situations, visual loss has been severe and permanent. Our case is unusual in its combination of disc edema with normal acuity along with its transient nature and resolution and to our knowledge, has not been published before.

Vision Loss and Recovery after Baerveldt Aqueous Tube Shunt Implantation.

This study aims to determine the course of vision loss after Baerveldt aqueous tube shunt placement and identify risk factors associated with unexplained severe long-term vision loss, or snuff-out. We retrospectively reviewed 247 eyes of 222 patients who underwent Baerveldt implantations at one of two academic institutions. Postoperative vision loss at 6 months following surgery was categorized as mild-to-moderate versus severe and long-term versus transient. Long-term vision loss, defined as 3 or more lines of Snellen visual acuity (VA) loss compared with preoperative VA, occurred in 63 of 247 eyes (25.5%), and 39 had mild-to-moderate and 24 had severe loss. Of these 63 eyes, 18 had no identifiable cause of vision loss. On multivariate analysis, poorer Snellen VA on postoperative day 1 (POD1) was found to be a significant risk factor for long-term vision loss (p = 0.005). In addition, the negative change in preoperative versus POD1 Snellen VA (p = 0.021) and the presence of split fixation involving the inferonasal quadrant on preoperative Humphrey visual field (p = 0.044) were significant risk factors for snuff-out. Transient vision loss occurred in 76 of 242 eyes (30.8%). In conclusion, vision loss is not uncommon after Baerveldt surgery, with snuff-out occurring in 2.4% of cases in this study.

Visual loss after spine surgery: Case report

The presence of postoperative visual loss is a well-known complication, and described in various reports, its low incidence (0.028–0.2%) makes it extremely rare. Two main causes have been determined: Posterior Ischemic Optic Neuropathy and central Retinal Artery Oclusion. The following is a case report of a 52-year-old patient that presented visual loss after elective spine surgery that had no complications that could initially explain this complication. Studies were performed and evaluations by ophthalmologists determined that the cause of Posterior Ischemic Optic Neuropathy due to multiple risk factors that the patient had previously and during the surgery. After 3 year follow-up the patient still has total visual loss and no other complications were reported.

Perioperative visual loss following prone spinal surgery: A review.

Background:Postoperative visual loss (POVL) following prone spine surgery occurs in from 0.013% to 1% of cases and is variously attributed to ischemic optic neuropathy (ION: anterior ION or posterior ION [reported in 1.9/10,000 cases: constitutes 89% of all POVL cases], central retinal artery occlusion [CRAO], central retinal vein occlusion [CRVO], cortical blindness [CB], direct compression [horseshoe, prone pillows, and eye protectors Dupaco Opti-Gard]), and acute angle closure glaucoma (AACG).Methods:Risk factors for ION include prolonged operative times, long-segment spinal instrumentation, anemia, intraoperative hypotension, diabetes, obesity, male sex, using the Wilson frame, microvascular pathology, decreased the percent of colloid administration, and extensive intraoperative blood loss. Risk factors for CRAO more typically include improper positioning during the surgery (e.g., cervical rotation), while those for CB included prone positioning and obesity.Results:POVL may be avoided by greater utilization of crystalloids versus colloids, administration of α-2 agonists (e.g., decreases intraocular pressure), avoidance of catecholamines (e.g., avoid vasoconstrictors), avoiding intraoperative hypotension, and averting anemia. Patients with glaucoma or glaucoma suspects may undergo preoperative evaluation by ophthalmologists to determine whether they require prophylactic treatment prior to prone spinal surgery and whether and if prophylactic treatment is warranted.Conclusions:The best way to avoid POVL is to recognize its multiple etiologies and limit the various risk factors that contribute to this devastating complication of prone spinal surgery. Furthermore, routinely utilizing a 3-pin head holder will completely avoid ophthalmic compression, while maintaining the neck in a neutral posture, largely avoiding the risk of jugular vein and/or carotid artery compromise and thus avoiding increasing IOP.

Visual evoked potentials monitoring in a case of transient post-operative visual loss.

Post-operative visual loss (POVL) is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations.

How to avoid perioperative visual loss following prone spinal surgery.

Background:In a prior article, “Perioperative visual loss (POVL) following prone spinal surgery: A review,” Epstein documented that postoperative visual loss (POVL) occurs in from 0.013% to 0.2% of spine procedures performed in the prone position. POVL is largely attributed to ischemic optic neuropathy (ION), central retinal artery occlusion (CRAO), cortical blindness (CB), direct compression (prone pillows/horseshoe, eye protectors), and rarely, acute angle closure glaucoma.Methods:Risk factors for ION include prolonged surgery, extensive fusions, anemia, hypotension, hypovolemia, diabetes, obesity, use of the Wilson frame, male sex, and microvascular pathology. CRAO may result from improper prone positioning (e.g., eye compression or rotation contributing to jugular/venous or carotid compression), while CB more typically results from both direct compression and obesity.Results:Several preventive/prophylactic measures should limit the risk of POVL. The routine use of an arterial line and continuous intraoperative monitoring document intraoperative hypotension/hypovolemia/anemia that can be immediately corrected with appropriate resuscitative measures. Application of a 3-pin head holder completely eliminates direct eye compression and maintains the neck in a neutral posture, thus avoiding rotation that can contribute to jugular/venous obstruction and/or inadvertent carotid compression. In addition, elevating the head 10° from the horizontal directly reduces intraocular pressure.Conclusions:The best way to avoid POVL following prone spine surgery is to prevent it. Routine use of an arterial line, intraoperative monitoring, a 3-pin head holder, and elevation of the head 10° from the horizontal should limit the risk of encountering POVL after spinal procedures performed in the prone position.

Unilateral postoperative visual loss in a patient undergoing hip arthroscopy in the supine position: a case report.

Micro-emboli have been reported to occur commonly during arthroscopic surgery, which is frequently performed as an orthopedic surgical procedure. We here report a patient who experienced unilateral postoperative visual loss after a hip arthroscopy using irrigation fluid in the supine position without any evidence of external compression to either eye throughout the surgical procedure. Retinal fundoscopy suggested that the patient had central retinal artery occlusion, one of the causes of the postoperative visual loss. This case suggests that arthroscopic surgery may pose a substantial risk for paradoxical air embolism, such as central retinal artery occlusion, and suggests the need to prevent the entry of micro-air bubbles during such a type of surgery.

Anaesthetic concerns of a pregnant patient with Pott's spine for spine surgery in prone position.

Sir, Surgical decompression is the treatment of choice in pregnancy complicated by spinal tuberculosis with neurologic deficit.[1] We report the anaesthetic management of a pregnant patient with Pott's spine in prone position and discuss the various anaesthetic concerns including haemodynamic instability. A 23-year-old multipara, 17 weeks of gestation, weighing 52 kg, with Pott's spine involving T7–T10 segments with progressive neurological deficit was scheduled for decompression and posterior screw fixation. Obstetrician's opinion was sought. Preoperative foetal heart rate (FHR) was documented. Anti-aspiration prophylaxis was administered. Her baseline HR was 112/min and blood pressure (BP) was 132/82 mmHg. Invasive arterial BP monitoring could not be done due to the logistic problems. General anaesthesia was induced with propofol and morphine. Endotracheal intubation was facilitated using vecuronium with size 7.0 orotracheal cuffed tube. Injection glycopyrrolate 0.2 mg was administered as anti-sialagogue. Anaesthesia was maintained with isoflurane in 50% nitrous oxide and oxygen mixture. Soon following positioning, patient developed hypotension i.e., more than 20% fall from the baseline systolic BP (SBP). Fluid replacement and pressure-free abdomen were rechecked but the SBP continued to remain between 90 and 100 mmHg. Initially, hydrocortisone 100 mg was administered intravenously. The oozing from the surgical site resolved following injection tranexamic acid 500 mg. Surgery lasted for 5 h but BP persisted in the same aforementioned range. Blood loss was 1000 ml approximately. Haemodynamics and FHR remained stable post-operatively. The anaesthetic concerns related to spine surgery in pregnant patient include both obstetric and surgery-related i.e., prolonged surgery in prone position, major blood loss, relative hypotension and risk of postoperative visual loss.[2] The risk of radiation is of paramount concern due to the inability to use abdominal shield and the proximity of radiation to the foetus. The additional problem with prone position here includes the inability to perform emergent caesarean section. Technical problems may limit the usefulness of continuous FHR monitoring between 16 and 20 weeks and it is recommended to document FHR before and after surgery which was done in our patient. The American College of Obstetricians and Gynaecologists recommends continuous FHR monitoring in non-obstetric surgery from 18 to 20 weeks of gestation, based on the patient and the surgery to be performed.[3] There has been controversy related to the use of controlled hypotension and intraoperative tests/monitoring to detect spinal cord injury during pregnancy. Invasive arterial BP monitoring must be performed, more so, if controlled hypotension is instituted. Various risk factors for haemodynamic instability in these patients include pregnancy-induced aortocaval compression, massive fluid shift, blood loss and prolonged surgery. In addition, autonomic dysfunction has been reported as the cause for high incidence of intraoperative hypotension in adult patients with thoracic spine tuberculosis.[4] In our patient, vasopressor was not considered to treat hypotension:First, because, as the SBP remained in the acceptable range of 90–100 mmHg, and second, its use could have further led to increased blood loss. Since the hypotension occurred soon after positioning, it could be attributed by factors such as pregnancy-induced aortocaval compression, pre-operative hydration status and autonomic neuropathy related to thoracic spine tuberculosis. The initial two factors were ruled out by ensuring adequate fluid replacement and free and hanging abdomen in prone position. It is also reported that prone position in pregnant patient is associated with lesser risk of aortocaval compression than sitting or lateral position.[5] To conclude, intraoperative haemodynamic stability is of paramount anaesthetic concern in pregnant patients with thoracic spine tuberculosis and autonomic dysfunction must be considered as a potential cause for intraoperative hypotension. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Letter to the Editor: Unilateral postoperative visual loss in a patient undergoing hip arthroscopy in the supine position.

Letter to the Editor: Unilateral postoperative visual loss in a patient undergoing hip arthroscopy in the supine position.

Postoperative Visual Loss After Spine Surgery and the Role of the Neurosurgeon

Postoperative Visual Loss After Spine Surgery and the Role of the Neurosurgeon