Ocular Manifestations After Acute Methanol Poisoning

Abstract

Acute methanol poisoning is first and foremost life-threatening. Otherwise, functional prognosis is mainly based on ocular impairment. In this case series we aimed to describe the ocular manifestations after acute methanol poisoning during an outbreak in Tunisia. The data from 21 patients (41 eyes) were analysed. All patients underwent a complete ophthalmological examination including visual fields, colour vision test and optical coherence tomography with evaluation of the retinal nerve fibre layer. Patients were classified into two groups. Group 1 included patients with visual symptoms and group 2 included patients with no visual symptoms. Ocular abnormalities were seen in 81.8% of patients with ocular symptoms. They included: optic neuropathy in 7 patients (63.6%); central retinal artery occlusion in 1 patient (9.1%); and central serous chorioretinopathy in 1 patient (9.1%). Mean blood methanol levels were significantly higher in patients without ocular symptoms (p = .03).

Keywords: Methanol poisoning; acute poisoning; case series; ocular findings; outbreak.

Figure 1.

A 20-year-old male was admitted 4 days following methanol ingestion complaining of abdominal pain, nausea and vomiting with acute persistent blurred vision in the right eye (OD). His pH was 7.3, anion gap was 16.34 mEq/L and his blood methanol level was 0.07 g/l. He did not receive dialysis. Ocular examination 5 days following the ingestion found his visual acuity was 20/20 in each eyes with a relative afferent pupillary defect iOD. Colour optic nerve photographs showed a swollen hyperaemic optic disc OD with filling in of the optic disc cup (a), normal appearance of the left (OS) optic disc with a cup-to-disc ratio of 0. 3 (b). Optical coherence tomography of the retinal nerve fibre layer showed temporal increased thickness in OD (c) compared with OS (d).

Figure 2.

A 25-year-old male was admitted 4 days following methanol ingestion complaining of acute persistent right eye (OD) blurred vision. His pH 7.37, anion gap was 22.5 mEq/L, and his blood methanol level was 0.018 g/l. He did not receive dialysis. Ocular examination was performed 5 days following the ingestion. His visual acuity was 20/25 in OD and 20/20 in the left eye (OS). (a) Colour fundus photographs of OD showed acute central serous chorioretinopathy presenting as central serous neurosensory retinal detachment (between white arrows). (b, c) representive photographic images of the fundus with grid graph of measurements indicating an increase of macular thickness in OD (b) compared with OS (c). (d, e) Swept-source optical coherence tomography indicated the presence of an optically empty space corresponding to the subretinal fluid beneath the fovea without retinal pigment epithelium detachment in OD (d) compared with OS (e). The choroid was thick in both eyes.