FOR YOUR EYES ONLY

Obtaining Eye care can be a confusing experience: Who should examine my eyes, will I need glasses and most important, are my eyes healthy.

In the coming months this column will provide information about some of the more common eye diseases and visual disorders. Eye diseases are relatively rare, although they become more common as we age. On the other hand minor eye disorders are fairly common and nearly everyone will require some vision correction at some time during their life.

POSTERIOR VITREOUS DETACHMENT

Most of the eye’s interior is filled with vitreous, a gel like substance that helps the eye maintain a round shape. There are millions of fine fibers intertwined within the vitreous that are attached to the surface of the retina, the eye’s light-sensitive tissue. As we age, the vitreous slowly shrinks, and those fine fibers pull on the retinal surface. Usually the fibers break, allowing the vitreous to separate and shrink from the retina.  This is a vitreous detachment.

Individuals developing posterior vitreous detachment (PVD) are commonly older adults with myopia (nearsightedness); women appear to be more prone. Although PVD is clinically found most commonly in older patients, it has been demonstrated to begin as an incomplete or partial PVD as early as the fourth decade of life. However, while the incidence of PVD is known to increase with age, PVD in elderly patients is not as common as initially thought. Only 46% of patients between ages 80 to 89 years demonstrate complete detachment.

PVD is typically seen bilaterally, but it does not frequently occur simultaneously. Patients with unilateral PVD tend to be younger. Those who develop PVD before age 30 often show the presence of associated diseases such as retinitis pigmentosa , non-diabetic retinal vascular disorders or posterior uveitis, inflammation of the uvea. PVD at this age may also follow ocular trauma. Once PVD has developed, the risk for fellow eye development within three years is 90%.

The patient will present with a sudden onset of floaters. There is usually one floating spot that is especially large and troublesome to the patient and often is the impetus to seek immediate care. Patients may also complain of multiple floaters or a moving cloud or curtain in their vision. Interior examination may show an annular circle- termed Weiss’s ring-present. This represents the former attachment of the vitreous to the optic disc and may appear as a complete or partial ring, a ball-like opacity or a hole without a ring. However, a visible ring is not present in every case and is not necessary to make this diagnosis.

There may be associated photopsia (flashing lights) if the individual is experiencing vitreoretinal traction. If the individual presents with multiple floaters, there may be an associated vitreous hemorrhage. In cases where there is also a vitreous hemorrhage , there may be a reduction in vision. While vision is not typically affected by PVD alone, visual reduction can result from vitreous hemorrhage, macular edema, epiretinal membrane or macular hole formation. There also always exists the possibility of a tractional retinal tear and/or retinal detachment.

Throughout life, there is a decrease in the vitreous gel volume and a subsequent increase in the liquid vitreous volume. This results in the formation of pockets of liquid vitreous termed lacunae. A PVD occurs when a loss of adherence takes place between the outer vitreous layer and the outer membrane of the retina.

MANAGEMENT

Any patient reporting a sudden onset of new or increased floaters, either with or without photopsia (flashing lights), needs prompt inspection of the vitreous and retina through a dilated pupil. A thorough examination includes the use of binocular indirect ophthalmoscopy , non-contact fundus lens biomicroscopy and three-mirror contact lens evaluation. While the presence of a PVD is visually troubling, it imparts no risk to a patient’s ocular health. However, tractional tears resulting from a PVD can result in a retinal detachment and must be detected and treated promptly.

Careful delineation of patient complaints and thorough inspection of the vitreous and retina will aid in proper management. It is not possible to predict, based upon symptoms alone, which patients will have a retinal tear concurrent with PVD. Approximately 7% to 14% of patients experiencing acute PVD will have a concomitant retinal break. The presence of pigment cells or hemorrhage within the vitreous strongly predicts the presence of a retinal break.

A patient with acute uncomplicated {VD still must be followed for the development of new retinal breaks.

REMEMBER  

• Patients with acute PVD with a small amount of hemorrhage into the vitreous and without an observable retinal break need a detailed peripheral exam. If no retinal break is detected, the patient needs repeat evaluation every two weeks for six weeks to look for an occult break not found upon the initial exam.
• Patients with acute PVD must be advised to report immediately if they note an increase in the number of floaters or decreased vision.
• Routine follow-up of patients with uncomplicated PVD may be unwarranted if they have no increased symptoms.

INFORMATION CONTAINED IN THIS COLUMN AND INFORMATION IN RESPONSE TO QUESTIONS RAISED IN THIS COLUMN, DOES NOT CONSTITUTE A CLINICAL DIAGNOSIS OR TREATMENT REGARDING A PARTICULAR DISEASE OR CONDITION OF THE EYE.

If you have any questions about eye care or common visual problems and diseases of the eye broached by this column; Please contact  mor_dtaw@yahoo.com