What Causes Floaters and Flashing Lights?
Ageing of the eye results in the vitreous gel (jelly-like substance in the eye) becoming less solid and degenerating. This is a normal process and is generally benign.
Degenerated parts of the vitreous gel that cast shadows on the retina are seen as “floaters” (Figure 1). Blood, pigment and inflammatory cells in the vitreous can also result in floaters.
You may find that floaters are more significantly noticed when you are outdoors under bright sunlight or when you are reading under bright light.
The degenerating vitreous may also pull on the retina, artificially stimulating it and producing the sensation of flashing lights.
Fig. 1 Floaters in a patient with vitreous degeneration.
What is the Retina?
It is a light sensitive structure at the back of the eye that enables the brain to process visual images. This is comparable to the role of film in a camera.
Cross section of the eye showing the relationship of the cornea, lens, vitreous and retina, and how the eye focusses light on the retina.
“Curtain” covering part of vision in retinal detachment.
What Causes Retinal Detachment?
- This usually occurs in the presence of a retinal tear. Degenerating vitreous pulls on the retinal resulting in a tear and fluid within the eye entering the tear. This leads to detachment of the retina from the wall of the eye (Retinal detachment).
- In the presence of retinal detachment, the sensation of a “curtain” blocking out part of a person’s vision may accompany floaters and flashing lights.
How Common are Retinal Detachments?
- Incidence of retinal detachment is only one in 10,000 to 15,000 persons. Not all retinal tears progress to retinal detachment. However, we recommend treating all retinal tears as it is difficult to predict which ones will lead to retinal detachments.
Who is at Risk of Retinal Detachment?
- Those aged 40-60 years.
- Highly short sighted younger individuals
- Trauma to the eye
When is it Necessary to Seek Consultation?
- Floaters - new onset or sudden increase in its number
- Flashing lights – new onset and accompanied by floaters
- “Curtain” blocking part of the vision - urgent consultation to exclude retinal detachment.
The purpose of examination is to exclude retinal tears and detachments as a cause of the symptoms as these conditions are potentially blinding.
What Treatments are Available?
- Sunglasses may help to reduce the awareness of the floaters under bright sunlight.
- Dimming the lights when reading will reduce the disturbance caused by the floaters.
- No treatment is required if vitreous degeneration is the cause of symptoms in the absence of retinal tears.
These symptoms may become less obvious or disappear with time.
- Laser therapy for retinal tears and certain types of retinal detachments.
- Surgery for most retinal detachments.
Buckle to the outside of the eye to support the tear as well as using cryotherapy to freeze the area of the tear to seal the break.
Gas injection to support the retina and close the break followed by laser or cryotherapy. This will required dedicated posturing after the procedure
Vitrectomy (surgical removal of the vitreous gel) may be required for more complicated cases. This is often combined with introduction of a gas or silicone oil into the eye in order to improve the success of the surgery. This will also require the patient to adopt a certain posture for a few days to weeks following the surgery.