*4.2.2 Principles of surgery*

Thus induction of PVD in diabetics is not similar to that performed regularly. In these patients, the primary step is truncation of cone. It is important to identify an area with hyaloid separation, and this leading edge can be held as a bucket handle and go circumferentially to truncate the cone (Video 1; https://cdn.intechopen. com/public/chapter\_videos/241965/VIDEO\_1.mov). In areas with dense adhesions, switching the site and going forth can help. At sites where the vitreous is very densely adherent and the above technique fails, viscodissection can be utilised to help induce separation. Once the anteroposterior traction is relieved, the membranes need to be carefully dissected out using a combination of various techniques described below to relieve the tangential traction caused by the FVP.

Two basic approaches to handle the membrane dissection are *outside-in* and *insideout* approaches. Depending on where the hyaloid is maximally separated, one would decide the approach. Although outside-in is a safer and commonly practised approach since the macula is spared, in some cases with flat and densely adherent membranes and/or where there is no PVD, an inside-out approach may be more helpful. However, it is not uncommon to encounter situations where one will require to use a combination of both these approaches depending on the hyaloid adherence. Sometimes, pockets of hyaloid separation can be noted adjacent to NVE and can be used as an initiating site.

Various techniques can be employed in the dissection of membranes as follows:


In scissors delamination, after identifying the cleavage plane, both the blades are placed beneath the membrane to severe them from underlying vascular attachments. Although initially described using horizontal scissors, these are now replaced by curved scissors (Video 3; https://cdn.intechopen.com/public/chapter\_ videos/241965/VIDEO\_3.mov).

Cutter delamination is now more commonly performed with the advent of smaller guage instruments, where the port is much closer to the tip and thus helps in better delamination. Various techniques of cutter delamination have been described [15]:


fold into the cutter, thus protecting the retinal surface. One should allow the membrane to fold up and fall back into the mouth of cutter rather than chasing the membrane into the cutter (Video 3; https://cdn.intechopen.com/ public/chapter\_videos/241965/VIDEO\_3.mov).


peeling. One has to be cautious while using PFCL in cases of posterior breaks, where traction is not relieved as there can be a chance of subretinal PFCL migration. Also forceful jet while injecting in cases with thin atrophic retinas can cause iatrogenic breaks during injection.
