A macular hole occurs when the vitreous gel exerts traction in the area of central vision, the macula. The pulling of the gel on the center of the retina results in the formation of an opening or hole in the central vision. Liquefied gel or fluid may enter this opening and collect under the retina, forming a cuff of fluid around the macular hole. Visual symptoms are caused by the missing retinal tissue in the center of the hole leading to a blind spot, as well as the cuff of fluid which creates distortion and waviness.
Macular holes typically occur in individuals in their 50's and 60's. This condition is more common in females. In most cases, the cause is unknown but macular holes have been reported after trauma, laser treatment, macular edema, macular pucker, and retinal detachment. The second eye is affected in approximately 15% of cases.
Clinical Appearance & Symptoms
Most macular holes present with an opening in the central retina surrounded by a cuff of fluid under the retina (Figure 1, 2). At this stage, patients typically complain of blurred central vision with an associated blind spot and distortion. The degree of visual loss, size of the blind spot, and level of distortion are often related to the duration of the macular hole. Sometimes, the duration of symptoms may be uncertain, as patients can often compensate with their unaffected, better-seeing eye. Eventually, patients often note a difficulty in depth perception when one eye is affected, and report problems with reading and performing fine motor tasks with that eye.
A macular hole is often diagnosed on clinical examination of the central retina. When a macular hole is suspected or discovered, certain diagnostic tests may be requested by your retinal specialist. The purpose of these tests is to confirm the presence of a true macular hole, identify possible underlying causes of the macular hole, determine characteristics of the hole, and plan possible treatment.
Optical coherence tomography (OCT) is commonly used to obtain a high-resolution image of the macular hole with its associated retinal traction and fluid. This technology uses laser light to scan the retina and construct an accurate cross-sectional image, non-invasively. The macular hole can be visualized to determine if there is indeed a full-thickness defect in the central retina. OCT is very useful at identifying areas of traction on the retina responsible for the macular hole, as well as depicting collections of fluid within and under the retina.
OCT is also very useful in helping to stage macular holes, which is valuable in planning possible treatment and determining the ultimate prognosis. Macular holes, as previously described, are often caused by traction of the vitreous gel on the central retina (Figure 3). A stage I hole occurs when this traction causes elevation of the central macula (the fovea), without causing a full-thickness hole in the retina (Figure 4). This is important, as approximately 55-60% of stage I holes will resolve on their own through natural release of the vitreous traction (Figure 5); for this reason, they are often followed closely without treatment. With continued traction, the remaining stage I holes progress to stage II in which there is a full-thickness defect or hole in the central vision (Figure 6). The symptoms are much more significant at stage II, and the hole will often enlarge over the next several months without treatment. This typically results in further visual loss and progression to stage III (Figure 7). Finally, in 20-40% of untreated macular holes, the vitreous gel will separate over the hole spontaneously and progress to stage IV (Figure 8).
Fluorescein angiography may be employed in the diagnosis of macular hole. In this procedure, a dye is injected into an arm vein and travels through the circulatory system to the eye. The dye acts as a tracer and is photographed as it passes through the retinal circulation. This technique may be useful for evaluating possible underlying causes of macular hole or differentiating macular hole from other conditions such as macular edema, macular pucker, and macular degeneration. Fluorescein angiography of a macular hole shows a focal bright area in the central retina, corresponding to the defect (Figure 9).
Most stage I macular holes are observed periodically for spontaneous resolution or progression to stage II. A highly symptomatic stage I hole may be a candidate for surgery after a thorough discussion with your retinal specialist. A stage II or higher macular hole is usually recommended for surgical intervention. Those who are not candidates for surgery (health reasons, physical limitations) or who do not desire surgery will typically progress until the vision reaches approximately 20/200. Although the central visual loss is rather severe at this level, patients will routinely preserve their side vision in the affected eye. Additionally, they often can compensate with the unaffected eye.
Surgery is the only definitive treatment for effectively removing the traction from a macular hole, sealing the central defect, and attempting the restore lost central vision. The procedure is called vitrectomy and involves removal of the vitreous gel and its attachments to the retina through tiny openings in the eye. Sometimes, the inner-most layer of the retina, the internal limiting membrane, is also peeled to assure complete relief of traction from the macular hole. At the end of the procedure, the vitreous cavity is filled with a gas bubble to gently press against the hole and help seal the edges. This bubble lasts from 2-6 weeks, and patients cannot see normally through the bubble until it disappears naturally. Patients are often asked to position with their face down for several days to 'float' the bubble against the macular hole and help close the defect. After macular hole surgery with a gas bubble, one cannot fly in an airplane or travel to high altitude since the bubble will expand under these conditions and cause a potential dangerous increase in eye pressure. In rare cases, an oil bubble is used to seal the hole instead of gas; patients may fly with an oil bubble, but do require a second surgery to have this type of bubble removed.
Visual recovery after vitrectomy for macular hole usually occurs over several weeks. The first sign of visual recovery occurs after 2-6 weeks, following reabsorption of the gas bubble. Over 90% of macular holes are successfully closed at this stage after a single surgery (Figure 10). In these cases, patients typically report significant improvement in blurred vision and distortion, although many are left with some degree of residual visual loss or symptoms. The cause, duration, baseline vision, stage, and severity of the original macular hole all play a role in the ultimate prognosis following surgical intervention. Cataract progression is common following this type of surgery, but is usually not of great concern since most macular hole patients already have mild baseline cataracts due to their age. Less common complications include retinal tear (2%) and retinal detachment (<1%), both of which are generally treatable. Bleeding and infection are rare complications associated with any surgery.