(1)
St. Johns, FL, USA
(2)
Helen Keller Foundation for Research and Education, International Society of Ocular Trauma, Birmingham, AL, USA
(3)
Consultant and Vitreoretinal Surgeon, Milos Eye Hospital, Belgrade, Serbia
(4)
Consultant and Vitreoretinal Surgeon, Zagórskiego Eye Hospital, Cracow, Poland
52.1 General Considerations
52.1.1 Indications
There are several possible indications for PPV in patients with diabetes: macular edema (see Chap. 49), vitreous hemorrhage (see Sect. 25.2.7.1 and Chap. 62), and proliferative disease with the newly formed membranes threatening or actually causing TRD.
In eyes with the TRD involving the macula,1 the decision to indicate surgery is easy; it is much more of a dilemma when the macula itself is spared, the VA is full (see Sect. 46.1.1), but the ophthalmologist notices that the TRD is gradually approaching the center. Based on extensive counseling, the patient has to choose between two options, neither of which is really reassuring.
Wait until the macula is also detached. By this time the VA already dropped and may not be fully restored even if all goes well during surgery.
Operate before the macula detaches. Vision may still be full, apparently threatened more by the operation than the disease.
Pearl
As a general rule, the earlier surgery is performed in an eye with PDR, the better the chances of a good anatomical and functional outcome.
52.1.2 Preoperative Considerations
Panretinal laser treatment should be performed in all eyes with proliferative disease.2
Once you have TRD, only areas without membranes3 should be treated, to avoid causing iatrogenic contraction of the tractional membranes.
Intravitreal anti-VEGF medication (bevacizumab) should be injected 2–3 days preoperatively.
The main goal is to reduce the risk of intraoperative bleeding, but the drug also makes separation of the proliferative membrane from the retina easier.
To avoid a rebound effect after the injection, the patient must be warned that the operation must take place as scheduled. If for whatever reason it has to be postponed, the injection should be repeated every week or so until the surgery can go ahead.
Monitoring the patient’s systemic condition (glycemic control, blood pressure etc.) is a crucial part of the management.
Commonly, the indication for surgery is a combination of TRD, ME, and VH. The patient must be advised that any of these may recur, even if surgery was a complete success. The VH is especially prone to recurring, even if no treatable pathology is present (see Sect. 35.4.3.2).
Pearl
The diseased vessel wall is the reason for VH in eyes with diabetic retinopathy. Even in the absence of neovascularization, the vessel may be unable to resist the elevated blood pressure, explaining why the rebleeding frequently occurs shortly after waking up. Such a “morning hemorrhage” may occur even if the blood pressure is well controlled.
52.2 Surgical Technique
Much of this has been described in Sect. 32.3.2; only certain aspects of the surgery are discussed here.
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