“As many of you know, I lost my sight,” John said. “I have a hard time watching it, but I love hearing it.”

The loss of his vision was the result of an eye infection that he had been struggling with since the summer, according to an Instagram post from September, which resulted in limited vision in one eye.

“Unfortunately, I lost the vision in my right eye in July,” John said in a Nov. 25 interview with Good Morning America. “It’s been four months since I’ve been able to see again.”

John hasn’t revealed the nature of the cause of his eye infection, but the musician admits he had problems.

“I’m kind of stuck right now,” John told GMA. “Going into the studio and recording, I don’t know because I can’t imagine any lyrics at first.”

Despite everything he is going through, John says he is grateful for the care he has received and the support around him. In his September post, John said he was positive about the recovery so far.

“I am recovering, but it is an extremely slow process and it will take some time before the affected eye can see again,” he wrote.

But how does an eye infection cause blindness? Here’s what you need to know.

What causes eye infections?

According to the American Academy of Ophthalmology (AAO), you can get eye infections from bacteria, fungi, parasites, or viruses. Eye infections can result from eye injuries, when you rub your eye after touching a dirty surface, or when you sleep or wear dirty contact lenses.

What types of eye infections are there?

The most common eye infection is conjunctivitis, or conjunctivitis, which is often caused by the same viruses as the common cold. It causes red eyes with sticky discharge and is extremely contagious but can be treated at home. Depending on the type of bacteria, you may need antibiotics.

Other types of eye infections include:

Certain types of eye infections can cause blindness, especially if left untreated.

How to recognize an eye infection

Here are some symptoms to look out for if you’re worried you have an eye infection:

• Eye pain or irritation
• Red eyes
• Sensitivity to light
• Blurred vision
• Itchy or burning eyes
• Watery or thick discharge
• Swelling and redness of the eyelids

How to prevent eye infections

The Cleveland Clinic recommends the following to minimize the risk of an eye infection:

• Wash your hands frequently.
• Don’t rub your eyes.
• Wear safety glasses when working or playing sports.
• Do not share items that come into contact with your eyes, such as towels or eye makeup.
• After an eye infection, throw away cosmetics to avoid becoming infected again.
• Clean your contact lenses and the contact lens case.
• Take allergy medication to prevent eye irritation.
• Contact an eye doctor if you notice symptoms of an eye infection.