Shocking convergence

Low-voltage shock leaves lasting visual effects.

Aidan Hanratty

Posted: Wednesday, December 4, 2019

A 38-year-old male with no past medical history presented one week following a low-voltage alternating current injury, said orthoptist Eamonn Nugent. Contact to the electrical source lasted approximately four-to-five seconds and entered via his right hand, Mr Nugent told the Annual Conference of the Irish College of Ophthalmologists.
The patient’s chief ocular complaints were vertigo and horizontal diplopia, as well as difficulty reading and in recognising faces. He also suffered right-sided muscle weakness, muscle spasms, headaches and self-reported psychological changes.
His visual acuity was 6/9 in both eyes, with no relative afferent pupillary defect, no lens opacities and with normal anterior and posterior segments.
An orthoptic exam showed orthophoria, but motility testing showed bilateral restrictions of upgaze and convergence was defective at 15cm. MRI and CT scans yielded no significant findings, and OCT results were unremarkable.
“As a differential diagnosis of this patient, the bilateral restrictions of upgaze and the convergence being defective does suggest the dorsal midbrain region has been affected,” said Mr Nugent. Furthermore, functional overlay could not be ruled out.

Convergence exercises
In an attempt to relieve the convergence insufficiency, the patient was given reading glasses, and three-times-daily dot card convergence exercises were prescribed.
Eight weeks later convergence improved to 12cm, but the patient continued to have restriction of upgaze. He also said that he could see cars but no one inside them and had continued to have difficulty recognising faces.
The patient also reported a complete change in character, adding that he felt like a 70-year-old man and suffered from depression and severe fatigue. He also became unemployed.
The patient requires frequent therapeutic monitoring, as the literature suggests that changes following electric shocks can take between days and years to manifest.
“Interestingly, the retina and optic nerve are known to have a higher electric resistance in comparison to other areas, so this may be another reason for why they’ve been spared in this case,” said Mr Nugent. Subsequent electro-diagnostic testing may yet give more information about the patient’s retinal function, he added.
While electric injuries are uncommon, they can have a devastating impact on patients. According to Mr Nugent, most of the literature is focused on high-voltage or lightning-strike-type injuries, especially within ophthalmology, so this case shows the damaging effects of even a low-voltage injury.
“We need to implement further frequent therapeutic monitoring for this patient and we also made sure there was onward referral to neurology and medical psychology,” said Mr Nugent, acknowledging the various symptoms the patient has been suffering.
Eamonn Nugent: