Sore and itchy eyes could be an early sign of a Covid-19 infection, new findings suggest.
Researchers have concluded that having problems with the eyes may be an indicator that someone has contracted the virus, with symptoms starting within two weeks before any other signs occur.
Symptoms to look for
While a high temperature, a new and continuous cough, and a loss of taste and smell are the most common symptoms of Covid-19, a recent study found that having sore, itchy eyes was one of the most significant ocular symptoms in coronavirus patients.
The research, published in the BMJ Open Ophthalmology, also indicated light sensitivity - known as photophobia - as another sign of virus infection.
Researchers from Anglia Ruskin University studied data from 83 Covid-19 patients and found the following symptoms were the most reported:
- Dry cough - 66%
- High temperature and fever - 76%
- Fatigue - 90%
- Loss of taste and smell - 70%
However, when assessing eye-related symptoms, the team found 18 per cent had suffered from photophobia, 17 per cent had itchy eyes and 16 per cent reported having sore eyes.
When do eye symptoms occur?
The study found that the frequency of sore eyes was significantly higher when a person experienced the main three coronavirus symptoms, rather than beforehand. But as many as 81 per cent reported experiencing eye symptoms within two weeks of other Covid-19 symptoms occurring.
Four in five patients said their eye-related problems lasted for less than two weeks in total, and no differences were found between males and females.
Previous studies have suggested that Covid-19 may cause eye infections, such as conjunctivitis, although the World Health Organisation (WHO) lists it as one of the less common signs.
Meanwhile, Italian researchers found early on in the pandemic that Covid-19 could remain in a person's eyes for up to 21 days after they first develop symptoms.
Scientists at the National Institute for Infectious Diseases found that a 65-year-old woman had red, infected eyes before the classic coronavirus signs showed, and remained in her eyes for exactly three weeks. Researchers examined her five days after she was discharged from hospital and found the virus had returned to her eye fluid, and was still lingering even after her nasal swabs were clear of the virus.
This suggested to researchers that the virus was continuing to make copies of itself within her eye fluid, leading to warnings that conjunctivitis could be an early sign of coronavirus.
Conjunctivitis ‘too broad’
The team in Cambridge, led by Professor Shahina Pardhan, director of the vision and eye research unit at the Anglia Ruskin University School of Medicine, have since looked into eye symptoms further and found sore eyes to be the most significant symptom, not conjunctivitis.
Prof Parhhan explained: "The most significant ocular symptom experienced by people suffering from Covid-19 was sore eyes.
"Other symptoms associated with other types of conjunctivitis, such as mucous discharge and gritty eyes linked to bacterial infection, did not reach significance.
“The term ‘conjunctivitis’ is too broad and should be used with caution."
The College of Optometrists and The Royal College of Ophthalmologists added that it is unlikely patients would develop red eyes without other symptoms of coronavirus.
A spokeswoman said: "Recent reports have suggested that Covid-19 may cause conjunctivitis, and it is known that viral particles can be found in tears, which has caused some concern amongst eye health professionals.
"It is recognised that any upper respiratory tract infection may result in viral conjunctivitis as a secondary complication, and this is also the case with Covid-19.
"However, it is unlikely that a person would present with viral conjunctivitis secondary to Covid-19 without other symptoms of fever or a continuous cough, as conjunctivitis seems to be a late feature where it has occurred."