Macular Holes
The macula is the central part of the retina, directly in the back of the eye. Light from images are focused on the area, and because of its unique structure, a sharp image is relayed to the brain. Any damage to the macula will result in decreased vision, and one of these conditions is a macular hole.
A macular hole occurs when there is an absence of retinal tissue in the center of the macula, and since there are no longer any photoreceptors in this area, the light from images focused into this area are not perceived, resulting in a central blind spot. However, in the early stages in the development of the macular hole, symptoms may only be distortion or blurred vision. It is as if a person was shooting at a target, but the area of the bull’s eye had been removed. You would not know for sure if you had hit the bull’s eye or not.
How Does A Macular Hole Occur?
Within the eye is a gelatinous substance called vitreous. In early life the vitreous fills the hollow of the eye and is generally moderately adherent to the retina. With age the vitreous degenerates and the adherence to the retina weakens resulting in a separation between the retina and vitreous (posterior vitreous detachment). However, in the area of the macula, the adherence of the vitreous to the retina can be relatively tight, and when the vitreous separates elsewhere, there can be a strong anterior- posterior pulling on the macula resulting in a cyst formation. If the adherent breaks free, the cyst would resolve, and the macula would return to its normal position, and any disturbance in vision would disappear. If the vitreous does not break free, a small hole can be created. Over time the edges of the retina around the hole swells, and due to a tangential traction around the hole, it can get larger. As the hole enlarges there is a corresponding decrease in vision. Rarely, a macular hole can result from ocular trauma or prolonged swelling of the macula.
Diagnosis is made during a clinical exam and confirmed by a study called an OCT (ocular coherence tomography), which provides a side view of the retina, and reveals any associated elevation of the surrounding retina. It will also show any swelling of the retinal tissue and the presence of any scar tissue, all of which contributes to the decreased vision experienced and are important to know prior to treatment.
When Do You Know Surgery Is Necessary?
Surgery, “pneumatic maculopexy”, is the only option for the repair/closure of a macular hole. The only time when it would not be recommended is if there is a medical condition which would contraindicate surgery, or if the hole is longstanding and the chances of gaining improved vision is negligible.
What Is The Surgical Success?
Surgical success is very high in the 95% range. Improvement of vision after macular hole surgery is also, very high, in the 70 to 80% range, but it depends on the size of the macular hole and how long it has been present. Large macular holes, which have been present for over 1 to 2 years, generally do have a high visual success rate, although there is an occasional good result. Small, fresh macular holes do very well, and with closure, can result in the return of near normal vision. Occasionally, the macular hole does not close on the initial attempt and repeat surgery is necessary. This situation, however, results in a somewhat lower surgical and visual success rate. Also, with closure and return of vision, at some later date, the macular hole can reoccur. This happens rarely but when it does, the macular hole can be re-operated upon, with good results.
What Are The Surgical Risks?
As in any major intraocular eye surgery, there is the risk of a complication. The possible complications include a hemorrhage, infection, retinal detachment, scar tissue formation, no-closure of the macular hole, and increased intraocular pressure.They constitute a less than 5% risk and can be well managed when addressed promptly. In patients who have not had cataract extraction the risk of acceleration of the cataract can be as high as 70%, therefore, in the more elderly patients who already have moderate cataracts, the cataract is removed prior to performing the surgery to close the macular hole.
How Is a Macular Hole Managed?
The repair of a macular hole starts with a vitrectomy, i.e. the removal of the gelatinous substance which fills the interior of the eye. Once this is completed, the surface of the macula can be safely approached, and it is examined for the presence of any residual vitreous, which may still be attached to the retina. If present, it has to be removed and then any membrane causing tangential traction on the macula must also be removed. This membrane is often very thin and transparent, and is identified by staining. Once
stained, an edge is created in the membrane with a small instrument called a “retinal scratchier”, and then dissected off the entire area around the macula. Upon completion of this stage of the surgery, the fluid, which was placed inside the eye as the vitreous was removed, is itself removed and replaced with air, which is replaced with a special long-acting gas just prior to closing the eye. However, in a greater number of cases, an additional step is performed prior to placing the long-acting gas in the eye. This step is the application of a small drop of the patient’s serum followed by a small drop of thrombin to the macular hole. This creates a gelatinous plug, similar to a “scab”, which helps close the macular hole.
The use of the long-acting gas is to press on the macular hole, flattening the surrounding edges, which are often elevated, and preventing further swelling. The adjuvant therapy (the use of serum and thrombin) is felt to help pull the edges of the macular hole closed.
What Is The Recuperative Period?
Surgical recovery is relatively rapid, lasting approximately 3-6 weeks. However, positioning in the first 48 to 72 hours is critical. Positioning requires being face down, allowing the gas bubble to press against the macula. Therefore, while in bed the patients must sleep on their stomach and when out of bed must move around looking down at their feet. After 72 hours some of these positions may still be necessary, depending on the size of the bubble, this must be done to prevent pressing on the iris diaphragm. This could result in a dangerously increased pressure in the eye. The visual recovery is gradual and may take up to 6 months before optimal vision is achieved. During the recovery period, activity is somewhat limited to no running, jumping, stooping or lifting anything over 10 pounds. Topical eye meds are generally administered for 3 to 4 weeks post-surgery, and are tapered off by the fourth week.
Return to work depends upon the type of work the patient performs. Those who do a significant amount of strenuous work, will have a longer recuperative course then those who do not, but it rarely extends longer than 6 weeks, assuming there are not complications, even though the full recovery period for follow-up is 3 months.