Facebook
Twitter
LinkedIn
Email
 |
Checking for direct PDF access through Ovid | |
Excerpt
We read with interest the comments of Dr Schmidt et al. Their technique appears to differ from ours on two points:
1) They dilute ICG powder with distilled water. We prefer to use a 5% glucose solution in which the ICG powder dissolves much better. The 5% glucose solution has an osmolarity of 278 mOsm. 2) They “always avoid reinjection of ICG, which could potentially stain the bare retina.” In a series of 119 eyes that underwent surgical removal of macular epiretinal membranes, using transmission electron microscopy we analyzed each specimen and looked at the various types of layers that formed the “membrane” (to be published). Intraocular injection of ICG was not used in this study. In Group 1 (67 cases), only one membrane was removed surgically. In Group 2 (52 cases), a first membrane was removed and, owing to persistent retinal folds after peeling, a second membrane was searched for and peeled. When we analyzed the specimens of Group 1 and the first membranes that were removed in Group 2, we found that the retinal ILM was present in only 43 specimens (36%). In this series, we also observed that eyes in which the ILM had been peeled had a better final visual acuity and fewer recurrences than did those in which the ILM had not been peeled (P < 0.05). Accordingly, we came to the conclusion that ILM peeling is important to the success of macular epiretinal membrane surgery. Because in two thirds of cases in our study the ILM was not removed surgically during peeling of the first membrane, we now routinely perform an additional peeling to remove the ILM. In these cases, we have found that reinjection of ICG helps us to visualize the ILM better, thereby allowing a complete removal.
According to our technique, we inject 0.2 mL of ICG in front of the macula; the infusion of balanced salt solution is continued and the dye is removed 10 to 15 seconds later. The contact of dye with the retina is thus very brief. After reinjection of ICG, we have not seen any green coloration of the retina where the ILM has been removed. We assume that ICG does not fix to bare retina (without ILM). However, there is no experimental evidence that the absence of green coloration of bare retina means that there is no intraretinal penetration of ICG; this needs further investigation.
In contrast to our surgical approach for epiretinal membranes, we do not find it necessary to reinject ICG after ILM peeling in macular hole surgery.
