Point-of-care monitoring of perioperative intraocular pressure using portable tonometry in a patient with Posner-Schlossman syndrome: a case report
A 56-year-old male, 168 cm tall and weighing 71 kg, with a traumatic right rotator cuff injury, was scheduled for arthroscopic reconstruction surgery under general anesthesia. This patient had a history of diabetes mellitus and was taking oral hypoglycemic agents and insulin. For several years, he experienced recurrent episodes of severe left ocular pain and increased IOP, which later resolved. On close ophthalmic examination, he was diagnosed with Posner-Schlossman syndrome. There was mild epithelial edema of the cornea with a few keratic precipitates, and his cup/disc ratio was 0.5 with no visual field change. During the acute crisis period, the measured IOP in his left eye was above 30 mmHg and the IOP in his right eye was 13 mmHg. His symptoms were relieved after applying eye drops containing dorzolamide, a carbonic anhydrase inhibitor, and prednisolone acetate, but frequently recurred. Three weeks before his scheduled surgery, the IOP in his left eye rose again and he became extremely anxious about the operation. After consultation with an ophthalmologist, we decided to measure the patient's IOP intraoperatively using portable tonometry, and obtained informed consent from the patient for this perioperative risk.\nPreoperative laboratory findings, including hemoglobin concentration, liver function and coagulation tests, and arterial blood gas analysis, were normal, as were chest X-rays. The patient had a left axis deviation and an incomplete right fascicular block on electrocardiography and a mild restrictive pattern on pulmonary function test without any significant symptoms. In the morning of the day of surgery, the patient received 7.5 mg of midazolam per os. Before entering the operating room, his vital signs were stable, with a blood pressure of 133/75 mmHg, a heart rate of 82 beats per min, and an oxygen saturation of 99%. Two drops of 0.5% proparacaine hydrochloride were applied to each eye, and IOP was measured by portable tonometry (Tono-Pen Avia, Ametek, NY, USA) (). Initially, IOP was 19 mmHg in his left eye and 16 mmHg in his right eye. A 20-gauge catheter was inserted into his left radial artery to monitor continuous arterial pressure. Anesthesia was induced with propofol 100 mg, lidocaine 75 mg, rocuronium 50 mg, and a supplemental dose of fentanyl 100 µg, and ventilation was controlled to maintain end tidal carbon dioxide at 35 ± 5 mmHg. Anesthesia was maintained with 2-2.5% sevoflurane in an oxygen-air mixture (FiO2 0.5). Immediately after tracheal intubation, IOP increased to 23 mmHg in his left eye and 21 mmHg in his right eye, but decreased within 5 min to 14 mmHg and 12 mmHg, respectively. Initial arterial blood gas analysis showed an Hct of 39%, a pH of 7.48, a PaCO2 of 34 mmHg, and a PaO2 of 240 mmHg. After changing the patient's position to left lateral decubitus, the IOP was 15 mmHg in his left eye and 14 mmHg in his right side, but increased to 20 mmHg and 14 mmHg, respectively, after skin incision and arthroscopic insertion. The concentration of inhaled sevoflurane was adjusted in response to instantaneous IOP variation, and the occurrence of IOP surge was closely monitored. During the 210 min operation, the patient's vital signs remained stable and no adverse event occurred. Serial measurements by portable tonometry showed that his IOP remained within an acceptable range throughout the entire perioperative period (). The patient's postoperative course was uneventful.