292 |
32 Working with Membranes |
|
|
Fig. 32.7 Getting rid of a small ILM fragment stuck to the forceps jaws. In this picture the ILM is stuck to the jaw that is closer to the surgeon (the inferior one as viewed on the image). Twang that jaw with the light pipe after you brought the forceps to the light pipe – not the other way around so that you are away from the retina. Do not push the light pipe between the jaws but do the twang outside-in
•Except for a few eyes with high myopia, there is no ILM over the optic disc. Occasionally, a tiny hole is seen in the ILM over the foveola.
•The ILM may be missing over the major vessels: the tearing will occur exactly over them (see above). This is why ILM peeling is rarely extended beyond the arcades.
•Outside the major vessels, it becomes very difficult and eventually impossible to peel.
•In eyes with RD, especially if at high PVR risk, as large an area as possible should be peeled (see Table 54.9). Fortunately, in this scenario it is relatively easy to peel beyond the vascular arcades.
32.1.5 What If the ILM Cannot Be Peeled?
Although it is very rare that the ILM is impossible – or too risky – to remove, it may occur in the following cases:
•There is no PVD. With vitreous on the retinal surface, the ILM will tear, as it is too weak to withstand the weight of the gel (see Table 32.1).19
•Similarly, thick EMPs do not allow ILM removal (see below).
•Highly adherent ILM. This may be the case in very young children and some diabetics. It is a judgment call whether to continue or abandon – and if yes, at what point – the peeling.20
19In fact, the surgeon has difficulty even to grab the ILM through the vitreous cushion.
20I can recall 3 such eyes in my career.
32.1 ILM |
293 |
|
|
Table 32.1 Indicationsa for ILM peeling |
|
Indication |
Comment |
“Assuring the PVD |
This is a rather nonsense of an argument. ILM removal is not the correct |
has been done” |
way to achieve PVD; in fact, the presence of the vitreous cushion on |
|
the retinal surface interferes with ILM removal: the ILM tears under |
|
the weight of the vitreous. Conversely, very fine proliferative |
|
membranes may be removed together (as one piece) with the ILM |
|
(see below) – but in these cases the ILM comes off with the epiretinal |
|
membrane, not vice versa |
BRVO |
Sheathotomy at the arteriovenous crossing, in addition to dealing with |
|
macular edema (see below) |
Cellophane |
To remove the diseased surface and to prevent continual/recurring |
maculopathy |
growth |
EMP |
To ensure that all of the proliferation is removed and eliminate the risk |
|
of recurrence |
Hemorrhagic |
In the submembranous type, the blood-accumulation is under the ILM; |
macular cyst in |
once detached, the ILM never readheres |
Terson syndrome |
|
Macular edemab |
To help dry out, and keep dry, the retinac |
Macular hole |
To increase the success rate by eliminating all traction forces |
Optic pit |
A somewhat controversial indication since ILM removal can also |
|
weaken the already damaged retina on one hand, but may, on the |
|
other hand, help if a macular hole is present |
PDR |
Removal of current, and prevention of subsequent, membranes growing |
|
on the macular surface, in addition to dealing with macular edema |
|
(see above) |
Prophylactic |
Against the future development of EMP or edema, which may threaten |
|
in many diseases as well as the result of the treatment itself |
PVR |
Complete removal of current, and prevention of subsequently |
|
developing, membranes on the macular surface |
RD |
To prevent EMP formation and treat the edema in long-standing cases |
Staphyloma- |
Removal of the rigid ILM allows the remaining, elastic neuroretina to |
spanning central |
conform to the eye’s increased concave contour at the posterior pole |
RD |
|
VMTS |
To ensure that the traction is completely relieved |
aIn alphabetical order. See the appropriate chapters for more details. bOf different etiologies.
cThe mechanism how these goals are achieved is not clear, even if the clinical results are hard to dispute. Elimination of the traction, removal of the thickened ILM (barrier to oxygen transport from the vitreous), and a reactive, surface-perpendicular intraretinal gliosis, among other factors, have been cited.
•The highly myopic eye. The staining is usually faint, even with ICG, and the contrast is very weak, due to the depigmentation of the posterior pole. In addition, the retina is extremely thin,21 further increasing the risk (see Chap. 42).
–Although technically very difficult and associated with an increased chance of iatrogenic retinal damage, ILM removal in these eyes has extreme benefits; a careful consideration of risk vs benefit is needed.
21 Down to one-third of the normal.