This makes the case for ophthalmologists' reminders to never sleep with your contact lenses.
Last November 2016, a woman in the United Kingdom and her doctors were both surprised when they discovered she had 27 contact lenses in a single eye, according to Optometry Today.
The finding was only made public this July 2017 at the medical journal The BMJ.
Specialist trainee ophthalmologist Rupal Morjaria first found 17 lenses when the 67-year-old woman was being examined prior to a cataract operation.
Morjaria described the clump of lenses as a "blueish mass." Another 10 were extracted during a second examination.
In their 20 years of experience in the field, the operating team at Solihull Hospital said this was the first case of its kind.
"None of us have ever seen this before," said Morjaria. "It was such a large mass. All the 17 contact lenses were stuck together. We were really surprised that the patient didn't notice it because it would cause quite a lot of irritation while it was sitting there."
The patient allegedly did not know that she was wearing that many lenses, despite using disposable lenses for the last 35 years. She didn't have "regular optometrist appointments" and did not report symptoms in relation to the lenses.
According to Morjaria, after the lenses were removed, the patient said "her eyes felt a lot more comfortable. She thought her previous discomfort was just part of old age and dry eye."
With the discovery, the patient's cataract surgery was pushed back as she had a higher risk of contracting endophthalmitis. The condition occurs when the eye is infected and is considered sight-threatening.
"Because she had harboured these contact lenses in her eye for an unknown length of time, if we had operated, she would have had a lot of bacteria around her conjunctiva," explained Morjaria.
Both optometrists and ophthalmologists stressed the importance of having regular check-ups with professionals.
"Contact lenses are used all the time," said Morjaria. "But if they are not appropriately monitored, we see people with serious eye infections that can cause them to lose their sight."