Floaters and Photopsias (Black spots and flashes)

Many people visit their ophthalmologist complaining they see black spots or flashes in their visual field. These symptoms appear suddenly and worry the patient, since they cause discomfort. These symptoms are called floaters and photopsias and are usually caused by a posterior vitreous detachment. Since these symptoms might hide other more serious conditions, like retinal detachment or cracks, it would be wise to urgently visit out ophthalmologist for early detection and potential treatment. Let us look at these conditions in detail.

What are the floaters?

Floaters are black spots that look like “flies” and appear to move in our visual field, especially under bright lights or in front of a white background. These floaters are small concentrations inside the vitreous humor, a gel found inside the eye that keeps the eyeball in its spherical shape. As those concentrations move inside the vitreous humor, they cast a shadow on the retina, under bright conditions, and thus appear as black spots.

What are photopsias?

Photopsias are sparks or “flashes” that appear in our visual field mainly in the dark or under low light conditions. These photopsias are caused by the attraction of the retina from the vitreous humor. Those flashes can disappear and reappear for weeks or months.

What causes these symptoms?

As people reach middle age, the vitreous humor can increase in volume or shrink, thus creating concentrations in the eye. The vitreous humor can detach in its posterior segment and this condition is called posterior vitreous detachment. During detachment, the attractions on the retina cause flashes. It is a usual phenomenon and can happen to young people with myopia or patients that have undergone cataract surgery, a YAG laser procedure or had an inflammation inside the eye.


Some people see flashes of light that appear as irregular lines or “thermal waves” in both eyes, that usually last 10-20 minutes. These types of flashes are usually caused by spasms in the vessels of the brain, a condition known as migraine. If those flashes are followed by headache, the condition is known as migraine headache. However, those irregular lines or “thermal waves” can occur without headache. In that case, those flashes are known as ocular or silent migraines.

What should we do?

The sudden appearance of floaters or photopsias can be an emergency and, as a result, the patient, especially if he is over 45 years of age, should urgently visit his ophthalmologist in order to diagnose the problem. The test that must be done in this case is to examine the fundus (ophthalmoscopy) after applying eye drops that will enlarge the pupil so the doctor can clearly see the entire retinal periphery.

Can these symptoms be serious?

Provided there is a diagnosis for posterior vitreous detachment, then we shouldn't be worried, since our vision is in no immediate danger. This phenomenon is very usual and shouldn't worry us.

Warning: These symptoms, however, can be caused by some pathological and dangerous for our vision conditions like retinal cracks (tear) or detachment. For these reasons, we should urgently visit our ophthalmologist to get an early diagnosis and rule out these conditions, in order to stop worrying or, in case we are diagnosed, start a laser procedure, if there is a tear, or surgery, if there is retinal detachment.

So we should differentiate posterior vitreous detachment from retinal detachment. The first is not dangerous, while the second is dangerous and serious.

Is there a cure?

In case we are diagnosed with a retinal crack, then we should immediately undergo a laser procedure, in order to fortify the area and prevent a full detachment. In case of a retinal detachment the only option is surgical restoration. These cases, however, are less frequent, even if they are the ones that need to be paid more attention.

In case of posterior vitreous detachment, there is no particular treatment. This detachment is permanent and floaters and photopsias might always be present. Vitreous concentrations tend to move towards the front of the eye, so it is possible that the symptoms might weaken with time.

Since, statistically, a patient with vitreous detachment can also present retinal detachment, due to lack of mechanical pressure in the area of detachment and other attractions that are created, we should be careful, especially during the first month. We shouldn't bend down quickly, lift heavy items or make sudden moves. In case these symptoms worsen or increase, we should immediately visit our ophthalmologist to see if anything has changed.





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