WHAT IS IT?
Macular Hole is a condition where the center of the retina (the macula) develops a hole. The retina is the part of the eye that acts like a film in a camera. If a hole develops in the center of the retina, the resultant image becomes very blurred. In addition, because the edges of the hole cause the retina to be displaced, the image is often described as distorted by patients. The cause of macular hole is largely unknown. However, it is believed to be related to the gel at the back of the eye (the vitreous) detaching from the retina (known as a posterior vitreous detachment). The vitreous is normally loosely attached to the retina over the macula, and it is quite common for the vitreous to detach away from the retina in later life. As the vitreous detaches from the retina, it may cause undue traction at the macula (which because it is the part of the retina that provides the most detailed vision, it is also the thinnest part of the retina). This traction may be the mechanism whereby the retina forms a hole in the center.
WHO GETS IT?
Macular holes tend to occur in the 60-year plus age group, although occasionally they can occur in young patients, particularly after an eye injury and is occasionally associated with people who are very short-sighted (myopic). Studies have shown a slight preponderance of the patients suffering macular hole being female, though this may in part be explained by the increased life expectancy of women and this is a condition mainly affecting the elderly.
WHAT ARE THE SYMPTOMS?
Most patients suffering from a macular hole notice a gradual onset of loss of central vision, often associated with distortion (whereby straight lines become wavy). Gradually the central vision deteriorates further and in the majority of patients, if left untreated the central vision continues to deteriorate. Thus patients have difficulty reading, seeing detail, etc. The peripheral vision (used to navigate and provide our sense of spatial position) is not affected in macular hole unless further complications were to develop from the vitreous detachment. Rarely, a macular hole may lead to retinal detachment (which could affect the peripheral vision).
HOW IS IT TREATED?
Very early macular holes that have not yet become a full thickness retinal hole often heal spontaneously. For those that don’t, and become full thickness retinal holes, the vision usually continues to deteriorate and without treatment, the visual prognosis is poor. Fortunately, surgery offers an effective treatment for macular holes. With surgery, up to 90% of macular holes heal and become closed, resulting in an improvement in the central vision and a reduction in the central distortion. However, even successful macular hole surgery rarely returns the vision to a level that the patient had prior to the development of the problem. Therefore whilst surgery will usually result in improvement in symptoms, it is not a cure.
WHAT DOES SURGERY INVOLVE AND HOW SUCCESSFUL IS IT?
Surgery can be performed as a day case procedure (with no overnight hospital stay), and usually under local anaesthetic (though general anaesthetic may be better for those who are very anxious). The surgery takes approximately one hour to perform. The surgery aims to close the hole by removing the source of the traction that caused the hole in the first place (the vitreous gel). This is called a vitrectomy. In addition, a fine membrane on the surface of the retina adjacent to the hole is peeled away to aid hole closure.
Finally, a gas bubble is placed in the back of the eye. This gas usually lasts a few weeks, and acts as a force to help close the hole. It is important to remember that in the initial few weeks following surgery, the gas bubble within the eye causes the vision to be very blurred, but gradually the gas dissolves away. Thus, the outcome following surgery is only known several weeks later. After surgery, it is common for your surgeon to request that you position yourself so that you are looking in the “face-down” position. The rationale for this is that the gas bubble provides a force directly on the hole to help close it. As the gas will be buoyant, and because the hole is at the back of the eye, when the patient is on the “face-down” position, the force at the hole from the gas bubble is at its greatest. Though traditionally, patients were asked to posture for up to 2 weeks after surgery, evidence is emerging that suggests that such long posturing is not required and indeed many surgeons do not request the patient performs any “face-down” positioning at all.
The surgery is successful in closing the hole in approximately 90% of patients. Thus, the vast majority of patients notice a significant improvement in vision and a reduction in distortion of their central vision. As stated earlier, though the vision usually improves, it rarely returns to the level that the patient had prior to the onset of the condition. Furthermore, in a small number of individuals, whilst the hole successfully closes, the patient may subjectively not notice any improvement in vision or distortion. If surgery is unsuccessful (approximately 10%), surgery can be repeated. The development of cataract is almost inevitable after macular hole surgery though the time scale for the development of cataract is often variable. If cataract does develop after macular hole surgery (usually within five years), then cataract surgery can be performed as a further procedure. If cataract is pre-existing in addition to the macular hole, cataract surgery can be combined with macular hole surgery.