Flashes and floaters are two of the most common symptoms bringing patients to the attention of a retinal specialist. In this article, we’ll review the keys to appropriate evaluation and management of patients with these symptoms. In so doing, we hope to make you more comfortable dealing with patients with this type of problem.

A careful history can often help to distinguish the cause of photopsias (flashing lights). Try to determine the duration of the flashes and whether they are central or peripheral in location. Flashes that last only a split-second and are located in the peripheral visual field are usually due to vitreous traction on the peripheral retina. This occurs most commonly following a posterior vitreous detachment (PVD). As we age, the vitreous gel liquefies. Eventually, the vitreous may collapse in on itself, peeling away from the posterior retina as it does so. The vitreous peels from posterior to anterior but always remains attached to the most peripheral retina. With rapid eye movements, the vitreous may "slosh" around inside the eye exerting traction on these peripheral attachments. Because the retina has light-sensitive photoreceptor cells rather than pain-sensitive nerve endings, patients experience lightning-like flashes rather than discomfort when the vitreous exerts traction.

Scintillating scotomas are flashes that move in a geometric pattern, last for several minutes, and are associated with a visual deficit in the affected area. These are usually migrainous in origin and often precede the onset of headache. They typically affect homonymous hemifields in both eyes though patients often misinterpret the symptoms as being unilateral.

Floaters are almost always due to opacities in the vitreous gel which cast shadows on the retina. These opacities may be cells (RBCs, WBCs, or pigment), vitreous strands, retinal tissue (i.e. opercula), or any other non-transparent object in the vitreous. It is important to distinguish floaters from small fixed scotomas. The former continue to move immediately after an eye movement ends (floaters have momentum). Scotomas, on the other hand, are blank spots that remain fixed in position tracking eye movements exactly.

When examining a patient with floaters, look carefully at the vitreous for cells or other vitreous opacities. This can be done with the slit lamp (and no lens) by focusing behind the lens. Asking the patient to look down and then straight ahead will circulate the vitreous making it easier to see cells. If you’re unsure whether the opacities you see are cells, compare them with what you see in the vitreous of the fellow eye. The presence of pigment or blood in the vitreous is an important warning sign that a retinal tear may be present. 70% of patients with acute hemorrhagic PVDs have tears compared with only a 2-4% incidence in those without hemorrhage. The vitreous may also tug on retinal vessels causing a vitreous hemorrhage even in the absence of a retinal tear. Indirect ophthalmoscopy and/or 3-mirror examination should be performed on any patient with symptoms or signs suggestive of a retinal tear. Symptomatic retinal breaks usually require immediate treatment (usually the same day).

The most common cause of flashes and floaters is a posterior vitreous detachment. When the vitreous separates from the optic nerve, its ring-like translucent attachment site is frequently visible to the patient as a large floater. The presence of this "Weiss ring" is one of the only reliable signs that a posterior vitreous detachment has occurred. As the vitreous collapses in on itself, collagen fibers may coalesce to a degree sufficient to cause visible floaters.

Patients with acute PVDs should be reexamined in 2-4 weeks to be sure no breaks have developed. As long as an individual has vitreous traction as evidenced by persistent flashes, he or she should be periodically examined to make sure that a retinal tear has not developed. It is often more difficult to see vitreous opacities (including a Weiss ring) on follow-up than on the initial exam.

How to manage a retinal detachment

Even if you’re not going to be the one repairing your patient’s retinal detachment, there are a number of things you can do to help your patient.

How often have you read a description of a fluorescein angiogram and wished you could see the actual images? Well, now you can! The Retina Center has recently purchased equipment which will allow us to include digital images of your patient with our letters. We believe this provides an exciting opportunity to improve communication, education, and patient care.

We at The Retina Center continually strive to stay on the cutting edge both in patient care and in the service we provide to referring doctors. If you have any comments or suggestions, please feel free to call anytime or give us feedback through our webpage (www.focusonretina.com).