MYODESOPSIA






Ophthalmologist Carolina Valdivia, MD discusses myodesopsia (eye floaters), its causes, and offers a simple technique for diminishing its effects.





InterrogativeA 33 year-old male from Estonia writes:

Dear Dr. Valdivia,

My question is not about glaucoma, but you have a very informative website and I thought that maybe you could help me. For the past few years, I have noticed black specks that look like gnats flying in front of my eyes. This does not happen constantly, but their appearance is frequent and unpredictable. At first, I thought that my eyes were tired. I tried resting them periodically at work, but the flying gnats always returned. I then thought that maybe I had dry eye. I must have tried every brand of artificial tears available, but the flying gnats still came back. I went to see an eye doctor about this. He told me that I have myodesopsia and not to worry about it. HOWEVER, I AM WORRIED ABOUT IT! These flying gnats are driving me crazy. Since the eye doctor really did not explain things to me, I am wondering if maybe I have a serious disease that will get worse and worse. Can you please help me?



Carolina Valdivia, MDThank you for your question and for your trust in glaucoma-eye-info.com. Let me first clear up what appears to be a misconception. Although this website focuses on glaucoma, visitors can feel free to ask any question about eye care or general health. I will help as much as possible. Now let us address your question.

One of the most common ocular problems reported by patients visiting my office is seeing eye floaters crossing their visual field. The medical term for this is myodesopsia. I have treated many patients with eye floaters, some that are more anxious about the condition than others. Let me explain what they are, what causes them, and what you can do.

WHAT IS MYODESOPSIA?

Myodesopsia is the presence of unexplained images floating in one's field of vision. These take the form of seeing specks, small insects, and semi-transparent objects from gray to black that change position with the movement of the eyes. Shapes often are reported to be round or elongated. They particularly are evident when we look at a monochromatic (one color) space, such as a blue sky or a wall that is painted white (or another light color). Myodesopsia also is more noticeable when we are using a computer. The condition is annoying and is not helped by resting the eyes, rubbing the eyes, or using artificial tears (as you already have learned).

WHAT CAUSES MYODESOPSIA?

To understand the cause, we must first delve into a little eye anatomy. The largest percentage of the eye is composed of a gelatinous substance called the vitreous humor. It fills the eyeball and helps to maintain its round shape. However, the vitreous humor is not as homogeneous as it may appear to be at first glance. Millions of tiny fibers are intertwined within the vitreous humor. These fibers are attached to the retina at the back of your eye.

Eye floaters, also known as a vitreous opacity, occur frequently due to changes associated with aging. In fact, most persons over 50 years experience some degree of vitreous opacity, although it can occur at any age.

In infants and young children, the vitreous humor is a solid and clear gel that fills the center of the eyeball and is attached strongly to the retina. However, as we age, the vitreous humor changes its consistency and partially liquefies (synchesis), causing it to shrink and pull away from the interior surface of the eyeball (vitreous synerisis). This can lead to a condition known as posterior vitreous detachment (PVD), which is characterized by a weakening in the adhesion between the vitreous humor and the retina. Although posterior vitreous detachment can happen in any area of the retina, it most often occurs between the vitreous humor and macular area. Symptoms can be quite annoying in the days immediately following this event, but they almost always diminish over time.

In the process of shrinking and sagging, the vitreous humor clumps and becomes stringy. Pieces of this debris can block some of the light passing through the eye and cast small shadows onto the retina. Thus, what you actually are “seeing” with myodesopsia are the shadows produced by debris within the vitreous humor that are cast upon the retina. We perceive movement because the debris drifts within the vitreous humor. If it did not and remained stationary, a process called neural adaptation would render the shadows invisible. Unfortunately, this is not the case.

A vitreous opacity also can occur due to eye diseases such as uveitis, retinal detachment and vitreous hemorrhage. In fact, if you perceive a sudden increase in the number of eye floaters, contact your ophthalmologist immediately, particularly if you also are experiencing flashes of light or lose your peripheral vision. These can be signs of a retinal tear or a retinal detachment, which requires quick attention.

WHAT CAN YOU DO?

Generally, the visual acuity of the people who have a vitreous opacity is very good, unless there is an underlying eye disease that is causing it. Persons experiencing myodesopsia should be evaluated by an ophthalmologist to determine if it is associated with other diseases, such as the presence of lesions in the periphery of the retina that predispose one to retinal detachment. Depending on how these lesions look, your ophthalmologist either will recommend a treatment regimen or further observation. Other causes of eye floaters are side effects from medications, bacterial or fungal infections of the eye, certain chronic diseases, such as multiple sclerosis and systemic lupus erythematosus, and eye or head trauma.

Most eye floaters are of primary origin (not associated with disease) and pose no danger to the patient. Interestingly, focusing on eye floaters will teach your brain to recognize them as part of your visual field and they will remain prominent. The converse also is true, by focusing beyond the floaters, you teach your brain to ignore them and their prominence diminishes over time.

In some persons, a vitreous opacity can be so bothersome that it affects their quality of life. In these cases, a microsurgical procedure called a vitrectomy that removes all or a portion of the vitreous humor and replaces it with silicone oil or gas may be an option. Vitrectomy is very effective in treating myodesopsia. However, the procedure also carries substantial risks to some patients. Among these are elevated intraocular pressure, vitreous hemorrhage (bleeding into the vitreous humor), retinal detachment, corneal edema (fluid buildup in the cornea), and endophthalmitis (infection inside the eye). Thus, vitrectomy only is recommended for myodesopsia patients with extreme symptoms or when regular symptoms are causing other problems, such as elevated stress, anxiety, and depression.

In summary, if you have eye floaters, see an ophthalmologist to check for underlying disease. If no disease is found, you have nothing to worry about. Try the technique of focusing beyond the floaters as a means of teaching your brain not to include them in your visual field.

Carolina Valdivia, MD


REFERENCE:

Lang GK. Ophthalmology: A Pocket Textbook Atlas, 2nd Ed. Stuttgart: Thieme, 2006:285-304.

My goal in answering your questions is to provide you with information, clear up misconceptions, and to explain options so that you can have an informed conversation with your doctor. However, under no circumstances should my response to your question be considered a substitute for ongoing consultation and examination with your doctor. Since I have not examined you, I only can speak in terms of generalities, whereas your doctor has sufficient clinical details to evaluate your case specifically.




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