Innovations in Macular Hole Repair10:07 PM
While new scientific advancements have revolutionized treatment and even cured some systemic diseases in recent years, blinding eye conditions have remained stubbornly difficult to treat. For many, a diagnosis of severe vision loss or blindness is a forever diagnosis, with no cure or treatment possible. Full thickness macular hole was once a medical condition that held little to no hope; the macula is the central vision area critical for fine detail sight and while a complete hole in the tissue is rare (studies show around 0.09% of the population will develop a macular hole in their lifetime), the visual prognosis is very poor. Only about 5% of patients with full thickness macular hole will have vision of 20/50 or better, and 40% of patients will be worse then 20/200 in the affected eye (the criteria for legal blindness if both eyes are affected). But new innovations in macular hole repair may be making these numbers a thing of the past.
|A large full thickness macular hole as seen on retinal fundus imaging (above) and OCT imaging (below) via|
What is a Macular Hole
Macular holes can be caused by a number of different factors, both genetic, trauma related, and purely aging related. The inside of the eye is filled with a gel-like substance called the vitreous, and one of the places that this gel attaches most strongly is at the very middle of our central vision area called the macula. Whether from high prescriptions stretching the eye too thin, trauma causing sudden disruption, or just the normal aging process, the vitreous gel naturally begins to separate from the back of the eye with the passage of time (called posterior vitreous detachment). As this separation of the vitreous from the retina happens, sometimes the vitreous stays attached right at the central macula (or fovea), pulling the retinal cells of the macular region up and off with it. There are various stages of macular holes as the tissue is lifted up and away, but in full thickness macular holes an entire area of retinal cells are missing at the macula, causing a bling spot in that vital area of central vision.
|Macular holes often begin with simple traction; the vitreous gel that fills the eye attaches more strongly at the central macular area, so when it begins to pull away from the eye due to trauma or age, it may stay attached at the macula and beginning lifting the retinal tissue up and away with it. This is termed vitreomacular traction. via|
|In some, the traction on the macula does not release, and the separating vitreous pulls the macular tissue off with it, leaving a hole in the retina underneath. This hole will not self-repair, and since the macula is the central vision area, a missing plug of retina tissue at this vital spot is usually devastating to vision. via|
Traditional treatment for macular holes was limited; studies showed holes older than 6 months in age or larger than 400 microns were unlikely to benefit from macular hole repair. The technique was difficult for both doctor and patient. The doctor would remove all of the vitreous from inside the eye (called vitrectomy), then painstakingly peel away the layer of cells right on top of the retina (called the ILM or internal limiting membrane) with fine tipped forceps. Then the patient's eye was filled with a gas bubble and the patient would lie face down in a specific position to hold the gas bubble properly in place over the macular hole for a period of days to weeks. Unfortunately, larger or older holes didn't respond well even to these aggressive approaches, with only 47% of holes that were 1 year or older closing after surgery.
New treatments have been showing promise in repairing larger and older macular holes, however. In 2010 researchers reported a new technique for repairing large macular holes (400 microns or more). Instead of fully peeling away the ILM, researchers folded the tissue back and made a little flap of ILM right over the are of the macular hole. Gas bubble positioning was performed followed by 3-4 days of head down positioning, and the results were impressive: 98% of large macular holes were repaired with the ILM flap approach (compared to only 88% repaired in traditional methods). It is unknown why the ILM helps support macular hole closure, but doctors theorize that the basement membrane properties of the ILM supports abundant glial cells growth, and photoreceptors in surrounding areas of reitna are drawn towards the glial cells and begin filling in the macular hole.
|A. A 68 year old with large macular hole and 20/80 vision; B. 3 months post-ILM flap technique, the macular hole is repaired and vision improved to 20/30 via|
The most difficult macular holes to repair, with low success rates even with ILM flap procedures, are those associated with high myopia and posterior staphyloma. With significantly high prescriptions (typically -8.00 or higher), the retina is so elongated that the retinal tissue is stretched dangerously thin across the back of the eye. These patients are at a much higher risk of retinal detachments and even splitting of the retina right at the central area, an event called foveoschisis. There is so much tractional force on the retina from these severely elongated eyes that the macular holes associated are often massively large and resistant to closure by even the most advanced techniques. In a brand new surgical technique described by Dr. Dilraj Grewal and Dr. Tamer Mahmoud in June 2016, there is hope of a breakthrough. Doctors Grewal and Mahmoud treated a -15.00D myopic woman with 1100 micron macular hole that had previously failed repair from traditional technique with ILM peel and vitrectomy. Because the ILM was already removed (and with the size of the macular hole involved an ILM flap would have had very little chance of closure), the doctors instead removed an appropriately sized wedge of peripheral retinal tissue and laser barricaded around this area to prevent retinal detachment, then placed this wedge of retina to "plug" the macular hole. This procedure has been termed autologous retinal transplant, using the patient's own retina to patch the area of the macular hole, and this was the first of its kind in human case study. OCT imaging 3 months after surgery showed closure of the macular hole and improvement in vision from 20/200 prior to surgery to 20/80 at the last reported follow-up.
|Drs. Grewal and Mahmoud operated on a longstanding 1100 micron macular hole (seen in preop above) by transplanting a flap of retina from the periphery. At 3 months post-op OCT imaging shows complete closure of the macular hole, and at 7 months post-op there is continued improvement as the retinal layers continue to thicken and the flap integrates into the surrounding macular tissue. via|