“Power” ful eye causing postoperative blurring of vision after non-ocular surgery under general anesthesia

Field: Medicine (Health Sciences)

Dear Editor, Ocular complications can occur in patients following non-ocular surgeries under general anesthesia which range from transient blurring of vision to irreversible blindness.[1] We report a case where preexisting hypermetropia was the cause of postoperative blurring of vision. A 38-year-old man with no comorbidities was posted for laparoscopic orchidectomy for right undescended testis. Preoperative evaluation revealed no abnormalities. General anesthesia was induced with fentanyl 100 mg, propofol 120 mg, atracurium 30 mg, and intubated with 8 mm endotracheal tube. Anesthesia was maintained with oxygen, air, sevoflurane and atracurium 5 mg, and fentanyl 50 mg. Opticlude eye patch (3M India) was used to gently close the eyes during surgery. Surgery in supine position lasted for 1 h and was uneventful. After reversal with neostigmine 2.5 mg and glycopyrrolate 0.5 mg, the patient was extubated. Postoperative recovery was uneventful. 24 h later in the ward, the patient complained of blurring of vision in both eyes while viewing a mobile phone. Ophthalmologist's opinion was taken. Anterior segment examination including cornea was normal in both eyes. Fundus examination and extraocular movements were normal in both eyes. Uncorrected Snellen's visual acuity for distance was 6/12 right eye and 6/6 left eye and uncorrected near visual acuity was N6 in both eyes. On refraction testing, the patient had simple hypermetropia of + 1.5 diopters in the right eye and no refractive error in the left eye. On questioning, the patient accepted that he had some difficulty while reading small print even before the surgery but never visited an ophthalmologist. The patient was reassured and glasses were prescribed for hypermetropia following which the blurring of vision resolved. The causes of postoperative blurring of vision after non-ocular surgeries can range from simple corneal abrasion to serious retinal vascular occlusions and ischemic optic neuropathy.[2,3] Our patient complained of blurring of vision postoperatively. We ruled out corneal abrasion and other serious ocular causes. To our surprise, he had hypermetropia which was corrected with spectacles. In a study by Warner et al.[4] on 671 patients undergoing non-ocular surgery under anesthesia, 4.2% of patients experienced new-onset blurred vision of at least 3 days duration postoperatively. In most of them, it resolved spontaneously over weeks. 25% of patients with blurred vision required new corrective lens or changes to existing lens over the next 18 months. The authors found no significant risk factors. Our patient had hypermetropia preoperatively itself which got unmasked after surgery. Preexisting refractive errors can get exaggerated following surgical stress due to transient accommodative weakness and can cause blurring of vision postoperatively. Due to limited mobility in the postoperative period, patients commonly watch mobile and read books for a prolonged time. This constant focus on simple visual tasks may cause patients to notice any small change in their vision. Further studies are required to know the incidence and risk factors for the transient postoperative blurring of vision from refractive errors. It is also important to enquire about the difficulty in vision for both near and far during preanesthetic checkup in all patients coming for surgery as medicolegal documentation. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.