The incidence of herpes zoster ophthalmicus (HZO) tripled to 30.1 cases in 100,000 people in 2016 compared to 9.4 cases per 100,000 people in 2004, according to a large study from the Kellogg Eye Center at the University of Michigan. Their findings were presented in May at the Association for Research in Vision and Ophthalmology meeting in Vancouver.

Shingles, a reactivation of the varicella zoster virus responsible for chickenpox, will affect an estimated 30 per cent of Canadians. The symptoms are a red rash with blisters and can be accompanied by acute nerve pain. There are around 130,000 new cases of shingles in Canada each year, and the number of new cases of shingles has been steadily increasing. Around 13 per cent of patients develop postherpetic neuralgia, a complication affecting the nerve fibres that causes a burning pain to remain in the area long after the rash and blisters have disappeared.

Study author Nakul Shekhawat, an ophthalmologist at the Kellogg Eye Center, said that because of “the severity of the disease and potential sight-threatening complications,” it’s important to identify the most at-risk patients. Keratitis, uveitis and episcleritis are all possible complications of HZO.

Adults over 75 had a higher rate of incidence than younger adults, at 53 cases per 100,000. Incidences of HZO were also higher among whites (30.6 cases per 100,000) compared with other racial groups. Women were more likely to be at risk for HZO than men.

A vaccine for shingles is available in Canada, found to be 97 per cent effective for adults between 50 and 69 years old and 91 per cent effective in adults over 70, and is effective even for people that haven’t had varicella (chickenpox) infection.

“Older patients were at far greater risk for HZO, highlighting just how important it is for older adults to get the shingles vaccination,” said Shekhawat.