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Background
For many surgeons repair of macular holes is extremely successful,
with hole closure rates of 80-90% or greater. Some clinicians believe that removing the
internal limiting membrane (ILM) increases hole closure rates.
The ILM is the basement membrane which lines the internal surface of the
retina. Removal of the ILM assures that all contractile forces
are removed from the hole edge, and stimulates gliosis which
is necessary for hole closure. Because the ILM is a delicate
clear structure, it is difficult to visualize without the
aid of an adjuvant such as indocyanine green (ICG) dye.
Evidence
Numerous studies have illustrated that the ILM can be reliably
stained with ICG. Once stained, the ILM can be removed in
nearly all cases. Numerous studies of ILM removal during macular
hole surgery suggest a beneficial effect on hole closure rates.
Procedure
In the air filled eye, ICG is placed over the macula for about one minute and then removed. This stains the ILM green. A tear in the ILM is then created, and then the free edge of ILM is torn in a circular motion to create a “rhexis.”
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Risks
Recent studies have shown that ICG binds to the retina and nerve, and may persist in the eye for up to one year. Although most investigators feel ICG is safe for the eye, atrophic changes in the RPE have been observed, and visual recovery may be somewhat slower. ICG at a lower concentration may make these changes less likely to occur.
Comment
In our experience, removal of the ILM using ICG can reliably remove traction from the edge of the macular hole, and stimulate gliosis promoting hole closure. Our very high success rate of macular hole surgery without ICG, and the possibility of ICG related ocular toxicity has prompted us to use ICG only in chronic, stage IV, or recurrent macular holes.
1. Archives of Ophthal, Vol. 118, 2000, 1117
2. Am J Ophthal, 2002; 133; 89-94
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