In age-related macular degeneration, the ocular histoplasmosis syndrome, idiopathic subretinal membrane formation, myopia, pseudoxanthoma elasticum, and other diseases, a subretinal choroidal neovascular membrane (SRN) may form under the center part of vision, markedly decreasing vision (see the AMD section). Since 1992 surgical techniques have been developed to remove these membranes to attempt to improve vision, and are successful in a fair number of patients (see section on Subretinal Neovascular Membranes). Failures, however, are most often due to damage to the photoreceptors and retinal pigment epithelial cells (RPE), or recurrence of the membrane. The RPE is necessary for normal functioning of the retina and to allow discriminatory vision (see Anatomy).
If the RPE is damaged or destroyed by the subretinal membrane or surgery to remove it, there are only four choices: 1) leave the damage and hope that the cells that are left will mesh with the photoreceptors and return vision; 2) instill some growth factors or other agents not currently known to stimulate the re-growth of the native RPE across the defect (not currently possible); 3) transplant the cells; or 4) translocate the macula to a new area of RPE. The idea was first suggested in 1987 when investigators detached the entire retina with fluid and then separated it from its connections in the far periphery. The retina was then rotated and reattached back down onto good RPE and away from the area of the damaged RPE.
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Macular Translocation (Retinal
Rotation) |
This technique has taken several versions. The large retinal technique shown above and first described in 1987, and more recently a macular rotation technique described in Europe and Japan, in which the incision is made more posteriorly in the retina and only the posterior retina is rotated . Most generally, patients have silicone oil placed after these two types of operations and have problems with distortion and tilted vision due to the moving of the retina. There is also a high complication rate of retinal detachment and a development of proliferative vitreoretinopathy.
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Macular Translocation (Macular
Rotation) |
More recently a "limited" macular translocation has been described. In this procedure the retina is detached in approximately 1/3 of its area, and then the outer wall of the eye, the sclera, is imbricated (folded in upon itself) with sutures, effectively making the eye smaller. The retina is then reattached over this imbricated sclera, and therefore the retina is moved slightly from its original position. This technique is applicable only to smaller subretinal membranes (approximately 1 to 1.5mm of movement), and is not for every patient. Newer injectable medications have, for all intents, made these procedures obsolete.
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Limited Macular Translocation After the SRN is removed, the retina is detached (left) in the area to be translocated (gray detached retina and macula). Sutures are placed in the sclera (green) to allow enfolding of the sclera. |
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The sutures are then tightened to make the eye smaller (left) and then the retina is reattached with air or gas from the top toward the center effectively moving the retina down in relation to the area of the removed SRN. |
We performed a modified technique of that originally described (our version shown above), in that we used to remove the subretinal membrane at the time of the macular translocation, thus the entire operation is done at one time. Others are leaving the subretinal membrane in place, moving the retina, and then one to seven days later lasering the original membrane in its new position relative to the retina. In actuality, this procedure should be called an RPE, choroid, and scleral translocation, as the retina itself really doesn’t move, it is only detached and reattached, and the constituents under the retina are actually moved (the eye outer wall is shortened) in relation to the retina.
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Limited Macular Translocation Fluorescein angiography of preop (left) and postop (right) macula. The retina is detached superiorly, the sclera superiorly is imbricated (folded in on itself with sutures) and the eye is made smaller. The retina is then reattached from top to center and the fovea is moved down (actually it doesn't move-the sclera is moved under it). |
None of these procedures have been proven in long-term clinical trials, and are currently under investigation at a few centers, particular Duke Eye Center (Dr. Cynthia Toth). These techniques, however, have proven to be of benefit in other problems such as macular folds after scleral buckling and other problems and may prove to be beneficial in the future in the replacement of cells.
Disclaimer Stuff: The opinions expressed in this website are those of RVT. Diagnosis and therapy should be based on a thorough examination by and recommendations of a qualified eye provider.