Why do we have black spots in our eyes, and how dangerous are they?

Dr. Ohayon explains common dangers to our eyesight and why it is so critical to visit an eye doctor at least once a year above the age of 40.

 COVID-19 and the human eye. Can a drug used to treat eye diseases help fight the coronavirus? (Illustrative). (photo credit: PIXABAY)
COVID-19 and the human eye. Can a drug used to treat eye diseases help fight the coronavirus? (Illustrative).
(photo credit: PIXABAY)

Problems with our eyesight are troubling, but most of the time they are neither dangerous nor urgent. Not so for problems with the retina, however, because they can do real damage and even lead to blindness.

Dr. Avi Ohayon, senior retina and cataract surgeon in the eye department at Tel Aviv Sourasky Medical Center (Ichilov Hospital), explains what can endanger our sight and how to be aware of it in time.

What is the retina?

First of all, it's important to understand what the retina is and how it functions.

The eye is made up of a front part which includes the cornea and iris (our eye color) and a back part where the vitreous (a gel-like substance filling the eye cavity) and the retina are. The retina's job is to receive the light rays from the world outside and to translate them into an image that goes directly to the brain.

When we see black spots - sometimes called "flies" or spider's nets - it is mostly an outcome of changes in the vitreous which usually happen above the age of 50, but also happen to young people who are very shortsighted (high myopia).

Eye exam (370) (credit: Courtesy Rabin Medical Center)Eye exam (370) (credit: Courtesy Rabin Medical Center)

Ohayon explained that when there are problems in the retina, we can't see them in a mirror, but we can definitely feel them.

"There are strong symptoms, like one or a number of black spots or a number of "flies" moving about in the field of vision," he said. He also explained that many people have black spots, but in most cases, the brain learns to ignore them over time.

Still, "there are cases where the spots are thicker, bigger or are directly in the center of the field of vision. In this case, the patients complain about the severe disruption of their daily life and ask us to remove them."

The way to remove these "flies" is to operate on the retina (vitrectomy) and clean the vitreous cavity - that's where the floaters are. 

"We enter through the white of the eye in three places and suck out the gel," he said and explained that the operation is done under local anesthesia and isn't painful at all.

Recovery is very easy: the eye is bandaged for 24 hours, then treated with antibiotic and anti-inflammatory drops. During the first week, vision can be blurry, and afterward improve.

"When the retina detaches from the eye there is an immediate danger of blindness."

Dr. Avi Ohayon

The biggest danger: Retinal detachment

Unlike black spots, which everyone can have and are usually not cause for concern, in some cases these spots can point to a serious problem in the retina that can even endanger our sight.

One of the biggest dangers is a tear in the retina, which can cause a retinal detachment. "When the retina detaches from the eye there is an immediate danger of blindness," Ohayon said, adding that in this case, time is of the essence. "It's a matter of hours or days, most of the time the detachment is acute and one should seek help immediately."

"The first serious symptom is a sharp drop in sight, all of a sudden the vision in one eye decreases drastically," he explained. "In fact, there are a lot of cases where people are rubbing one eye and then notice that they can't see out of the other eye."

Black spots or bright flashes in the eye can be signs that quick attention is needed. The detachment can lead to retinal bleeding, a macular (retinal center) hole or an epiretinal (inner) membrane which also causes a drastic decrease in vision and requires surgery.

When cases like these happen, the vitreous is examined. If the retina really is displaced, a medical procedure is urgently needed.

The main risk factors are age and high myopia. "The overall recommendation is that everyone over the age of 40 should get the eyes checked once a year and people with myopia should start even earlier," the doctor said.

Ohayon concluded by saying that he recommends doing a quick check at home once every few weeks - just shut one eye first, then the other one, and make sure vision is good and stable in both eyes.