In this section, three interrelated subjects will be discussed and explained. You may only have one of these problems. Even if that is the case, it is essential for you to read about all three of these topics. Your increased awareness could prevent serious, undesirable consequences from delayed evaluation and treatment.
The eye is like a small ball. There is an outer shell that encloses the structures that allow us to see. The inside of the eye is unlike a ball in that it is not hollow. Instead, the interior of the eye is filled with a gel. This gel is known as the vitreous.
The vitreous is made up of numerous components. These include cells, small fibers, and various chemicals. These items are arranged to support the structures inside the eye. They are transparent, allowing light to pass freely through the interior of the eye.
As a person ages, the vitreous gel can have a detrimental change called liquefaction, a process in which a portion of the vitreous gel decomposes and separates into its liquid and solid components. The liquid part of the degenerating vitreous does not cause any undesirable effects. The solid components, however, clump and produce a translucent or opaque mass. Due to the random nature of vitreous degeneration, these small masses can take on any shape. The individual can then see them as floaters. Generally, floaters are more noticeable when the person is looking at a bright, light-colored background. On occasion, they can be large enough to be seen at all times.
Fortunately, vitreous floaters do not harm the eye in any way. Unfortunately, there is no currently available treatment. The natural outcome of floaters is varied. Most patients notice little change in their floaters over the years. Some patients experience an increase in their floaters with time. Others are fortunate, perceiving a relative decrease in the severity of their symptoms.
POSTERIOR VITREOUS DETACHMENT
When a posterior vitreous detachment occurs, the solid portion of the vitreous gel shrinks and separates from the retina. Bits and pieces of the retina are frequently pulled away with the movement of the gel. These retinal fragments produce very annoying floaters. These floaters are much more objectionable to the patient because they are much more massive. Like the smaller floaters, regrettably, there is nothing that can be done to treat them. These larger floaters also may remain unchanged, increase, or decrease in intensity over the years.
If you have not yet read the section on floaters, please do so now. If you do not understand the explanation on floaters, much of the description of flashes will be hard to follow.
As the vitreous gel degenerates and liquifies, it also shrinks. When the vitreous collapses upon itself, it pulls away from the retina. The vitreous is not entirely free to pull away from the retina. As mentioned previously, the vitreous is partially made up of small fibers. These small fibers not only permeate the body of the vitreous but also extend from the vitreous to attach to the retina, retinal blood vessels, and optic nerve. As the vitreous shrinks and pulls away from the retina, the small fibers tug on these retinal structures. This traction, most often, amounts to nothing. Under most circumstances, the vitreous pulls free from the retina in an uneventful fashion.
Occasionally, the vitreous does not harmlessly detach from the retina. Under these circumstances, the small vitreous fibers pull on the retina and tear it. When the retina develops a tear, part of the liquified vitreous can seep through the hole and produce a retinal detachment.
For many patients, warning symptoms precede the development of a retinal hole. These symptoms take the form of light flashes. These light flashes are caused by the mechanical traction of the small vitreous fibers pulling on the retina. Because the eye acts as does a camera, all visual phenomena are reversed. In other words, if the traction involves the upper retina, then the flashes will affect the lower visual field. Similarly, if the traction involves the left side of the retina, then the flashes will appear in the right peripheral visual field. Retinal detachments, even if repaired, cause a significant and frequently severe vision decrease.
Any person who experiences peripheral flashes of light or a sudden increase in floaters should be concerned about the possibility of an impending retinal detachment. It is more desirable to prevent a retinal detachment than to treat one. Prompt consultation with an ophthalmologist is imperative.
As mentioned above, the aging of the vitreous can lead to retinal hole formation. If this abnormality is recognized at an early enough stage, treatment is available which can significantly reduce the chances of a retinal detachment. The two most commonly used modes of prophylactic therapy for retinal detachment are laser photocoagulation, and retinal cryopexy.
Laser photocoagulation is a treatment that consists of the application of laser treatment to the area surrounding a retinal hole or an area of vitreoretinal traction. The retina absorbs the laser light. Heat from the laser destroys the retina precisely where the laser is applied. The resulting scar tissue dramatically reduces the chances of progression to a retinal detachment. Laser photocoagulation is a straightforward procedure. It is performed on an outpatient basis, and only topical anesthetics and dilating drops are required (these are the same medications that are used in the course of a routine eye examination).
Retinal cryopexy is a treatment that consists of the application of a probe to the outside of the eye. This probe is applied to an area that corresponds to the hole on the inside of the eye. The probe temperature is lowered to about -60° C. This freezing causes cold destruction of the retina surrounding the retinal hole. The resulting scar tissue greatly reduces the chances of progression to a retinal detachment. The cryopexy is not quite as simple a procedure as is the laser. It requires local anesthesia and is usually associated with a degree of discomfort. It is also performed on an outpatient basis.