Acute angle-closure glaucoma after total knee replacement surgery: case report and literature review

An early and correct diagnosis improves the prognosis of post-operative Acute angle closure glaucoma (AACG). A 65 years-old monophtalmus man was operated for a total knee replacement surgery, under general anaesthesia without any adverse events. The day after, the patient described recurrent periorbital pain in his eye, with ocular hyperaemia, and reduced visual acuity. A diagnosis of AACG was made and conservative treatment was started to reduce the intraocular pressure. In the post-operative AACG, several predisposing local factors including genetic predisposition, female gender, hypermetropia, increased lens thickness and small corneal diameter, can be added to a pupillary block induced by adrenergic and anticholinergic drugs used in anaesthetic procedures as risk factors. An acute and intensive periorbital or ocular pain, with or without visual disturbance, must aware the physician.


Introduction
Acute angle closure glaucoma (AACG) after non ocular surgery is a rare complication of general anesthesia. However, in case of delayed diagnosis, it may lead to blindness. Immediate diagnosis and appropriate treatment should be done to prevent visual loss [1]. We present a case of acute angle closure glaucoma after total knee replacement surgery under general anesthesia in a monophtalmus patient. In this case, the most likely trigger was the use of atropine and nefopam.

Patient and observation
Patient information: a 65-year-old monophtalmus man (ASA physical status I, BMI =28,36 kg cm -2 ) with knee arthrosis was scheduled for a total knee replacement surgery under general anesthesia. The preoperative assessment was unremarkable. General anesthesia was induced with IV propofol (3 mg kg -1 ), Fentanyl (3µg kg -1 ), and cisatracurium (0.15 mg kg -1 ) to facilitate tracheal intubation (size 7.5 oral cuffed tracheal tube). Mechanical ventilation was used. Anesthesia was maintained with a mixture of air and oxygen (50%: 50%) supplemented with isoflurane 1 to 1.5 minimum alveolar concentration, Fentanyl and cisatracrium reinjections as needed. Anesthesia lasted almost 3 hours. The patient received 8 mL kg -1 h -1 crystalloid infusion during the surgery. The act has occurred with hemodynamic stability. IV paracetamol (1g) and IV nefopam (20 mg) were administered 30 minutes before the end of the surgery and every 6 hours for postoperative pain relief. neostigmine and atropine were injected at the end of surgery for decurarization. No additional drugs were administered.
Clinical findings: on the first postoperative day, the patient complained of a reduced visual acuity associated with periorbital pain and nausea.
Diagnostic assessment: slit lamp examination revealed lid edema and conjunctival hyperemia. The iris showed fixed and mid-dilated pupil. Gonioscopic examination showed a narrow angle. Intraocular pressure was 30 mm Hg (normal intraocular pressure is 12-20 mm Hg).
Diagnosis: the diagnosis of acute angle closure glaucoma was made and in case of delayed diagnosis or absence of treatment, it may lead to blindness.
Therapeutic interventions: medical treatment included IV mannitol 20%, tunolol and pilolol eye drops and acetazolamide pills was given to the patient.
Follow-up: the next day, the intraocular pressure was normalized, and visual acuity was completely recovered.
Patient perspective: the patient did not claim any adverse reaction to the treatment and was satisfied with the result.
Informed consent: the patient did finally give his consent.

Discussion
This case illustrates unilateral AACG most likely related to general anesthesia. The development of AACG requires the coexistence of both a predisposed eye (eye with a narrow anterior chamber angle) and a pupillary block. A pupillary block may appear in different circumstances such as the use of mydriatic agents or a mydriatic situation. Usual risk factors for postoperative AACG are a genetic predisposition, female gender, shallow anterior chamber depth or hypermetropia, increased lens thickness, small corneal diameter, and increased age [2]. Additionally, precipitating factors have been described. There are pharmacologic manipulations of the pupil (Table 1), producing a partially or fully dilated pupil, and emotional factors. These 2 conditions are frequent in the context of general anesthesia [3]. Thirty-six cases of AACG related to anesthesia have been published. The gender distribution is 1 male for 3 females, with a mean age of 63 years (58-64 interquartile range). There were 27 unilateral and 9 bilateral cases. The main identified precipitating factors for the development of AACG were the stress and the use of atropine (80%) or scopolamine. Nine cases (25%) were related to ephedrine use.
In the present case, 3 possible triggering factors which are the stress, the use of atropine for decurarization and nefopam for postoperative analgesia could be incriminated. Nefopam, which is a non-opioid analgesic that inhibits reuptake of serotonin, norepinephrine and dopamine [4], is contraindicated in patients with known angle closure glaucoma because of its parasympatholytic effects. Atropine, which is used to relax the ciliary muscle and dilate the pupil, has long-acting anticholinergic action, and can induce AACG [5]. Moreover, the perioperative period carries the risk of psychological stress. However, general anesthesia and postoperative events often mask the first symptoms. The presence of hypotension or anemia, may enhance ischemic optic neuropathy, which is a much more frequent cause of postoperative vision loss than AACG, but in contrast with AACG, its prognosis is often poor [6,7]. The published cases of AACG are summarized in Table  2 [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The purpose of this observation is to insist on good preoperative patients´ evaluation. The search for preexisting eye damage would be necessary in a programmed functional surgery. In our case, in front of the existence of monophtalmia, a specialized ophthalmological examination should have been required. In fact, the preoperative diagnosis of glaucoma could change the choice of anesthetic technique and used drugs.

Conclusion
Acute angle closure glaucoma is a rare cause of postoperative visual impairment. The use of mydriatic drugs such as atropine on predisposed individuals may precipitate this acute event, therefore physicians´ awareness is required in order to quickly initiate the treatment.

Competing interests
The authors declare no competing interests.  Tables   Table 1: classification of drugs inducing acute angle closure glaucoma by administration route