The diaphanous membrane most likely represents true exfoliation of the anterior lens capsule. In true exfoliation, there is lamellar separation of the lens capsule. The separation is most often related to exposure to intense heat (ie, glassblower's cataract), inflammation, or trauma. Studies show that the capsule is thickened and the anterior portion splits, causing extension into the anterior chamber.1
For cataract surgery in cases of a lens with delamination of the anterior capsule, it is beneficial to stain with trypan blue. Staining the capsule will allow better visualization of the true capsule opening during creation of the capsulorhexis. This is important as it is easy to confuse the delaminated capsule edge with the true capsulorhexis edge. If only the delaminated capsule is grasped, an incomplete capsule opening can occur. For staining the anterior capsule with trypan blue, I recommend injecting the stain under an air bubble rather than under OVD. As the goal is to stain both the diaphanous membrane and the normal lens capsule, OVD may envelope the membrane and impede staining of the membrane.
After the capsule has been stained, I would inject a dispersive OVD such as chondroitin sulfate. With a dispersive OVD, there is less chance that the OVD will inadvertently exit the wound in a large clump and deflate the anterior chamber during the capsulorhexis. Chamber stability will allow better control of the capsule flap.
The diameter of the capsulorhexis opening should be larger and incorporate the area of the lamellar membrane. Because the delamination is located mostly in the superior half of the anterior capsule in the dilated view, I would start the capsulorhexis in the “normal” capsule area inferior and adjacent to the lamellar opening. Once the capsule opening has progressed to the area of the lamellar opening, I would proceed peripherally to incorporate the abnormal capsule inside the capsulorhexis.
During the hydrodissection, I would be careful to insert the cannula properly under the entire capsule and not into a false lamellar layer. Once the capsulorhexis and hydrodissection have been performed, the remainder of the cataract surgery should be routine, without additional risks.
1. Karp CL, Fazio JR, Culbertson WW, Green WR. True exfoliation of the lens capsule. Arch Ophthalmol. 1999;117:1078-1080.