Clinical Examples in Managing Diabetic Retinopathy

In previous chapters, the emphasis has been on a detailedunderstandingofaparticularaspectofdiabetic retinopathy. In this chapter the approach will be more topical and practical and the principles presented previously will be exemplified in characteristic situations. Actual cases will be presented with discussions regarding management. These cases were circulated among theco-authorsandcommentsonmanagementindepen- dently solicited and then compiled. The discussants for the cases used the comments as a springboard to review the literature and provide a synthesis that reflects both the diverse clinical judgments of the reviewers and the published evidence pertinent to the case.

16.1Case 1: Proliferative Diabetic Retinopathy with Dense Premacular Hemorrhage

in a Patient on Coumadin

A 52-year-old man with diabetes and hypertension of 24 years duration was taking warfarin for atrial fibrillation and congestive heart failure when he developed sudden painless loss of vision in the left eye. He had previously had multiple focal/grid and panretinal photocoagulation laser treatments to both eyes for diabetic macular edema and proliferative diabetic retinopathy. His visual acuity was R – 20/25, L – hand motions. The fundus of the left eye

D.J. Browning (*)

Charlotte Eye Ear Nose & Throat Associates, Charlotte, NC 28210, USA

e-mail: dbrowning@ceenta.com

is shown in Fig. 16.1. The international normalized ratio (INR) was 2.2. How would you manage him?

16.1.1 Discussion

It has been estimated that cases of dense premacular hemorrhage such as this comprise 6% of vitrectomy surgeries for complications of diabetic retinopathy, and it has been stated that this is an indication for prompt vitrectomy.1 The rationale for skipping a period of observation and hoping for spontaneous clearing is that dense premacular hemorrhage under a bridging scaffold of posterior hyaloid results in early proliferation of fibrous membranes with traction retinal detachment.1 It is not known whether a period of observation is detrimental in such cases. A few weeks of observation may not be risky, and would have the advantage of demonstrating to the patient that spontaneous improvement was unlikely. Patient understanding and full agreement with a surgical treatment plan is an important aspect to weigh.

Certain cases such as this one feature liquefied blood in the premacular, subhyaloid space. In these cases, rupture of the posterior hyaloid face with the neodymium YAG laser may lead to dependent movement of the blood and clearing without the need for vitrectomy.2 The experience of others, however, is that these hemorrhages in patients with diabetes are often clotted, and if this is the case, the YAG laser approach to treatment will fail.1 Two other approaches reported in this situation are an intravitreal injection of tissue plasminogen activator, 50 mg, or bevacizumab, 1.25 mg, together with an intravitreal injection of 0.3 ml of sulfur hexafluoride.3,4

Reports of all treatment approaches emphasize the need for complete panretinal photocoagulation to cause regression of any active neovasculariazation.1–4 A separate issue exemplified by this case is the management of warfarin therapy in a patient being considered for vitrectomy surgery. The growing consensus is that the warfarin need not be discontinued if there are valid medical indications for its use.5–7 More complicated regimens of switching from warfarin to heparin, discontinuing heparin shortly before vitrectomy, reinstituting heparin after surgery, and finally converting from heparin back to warfarin appear to be unnecessary. There are no randomized controlled trials, however, to address the issue definitively and the specific details of each case together with the treating physician’s experience and input from the patient’s internist may be the most important determinants in man-

agement decisions.

Three technical issues arise in such a case if the ophthalmologist recommends vitrectomy surgery. First, is this a case in which 25 gauge or 20 gauge technique is preferable, or does it matter? Twentyfive gauge surgery is associated with a faster

postoperative recovery, but there is concern that the 25 gauge cutter cannot resect dense fibrinous clots as efficiently as the 20 gauge cutter. Second, should a preoperative injection of bevacizumab be given to render less active any underlying neovascularization, as has been reported, especially given the anticoagulated status of the patient?8,9 Finally, if intraoperative oozing of blood in an anticoagulated patient is a problem, what are useful approaches at surgery?

In this case, the surgeon chose 20 gauge technique and was convinced that the 25 gauge cutter would have failed to successfully resect the thick subhyaloid clot. No preoperative bevacizumab was given. Intraoperative oozing of blood was a problem and was not controllable by raising the infusion pressure or with the use of intravitreal cautery. The technique used to manage the oozing was silicone oil tamponade as has been described previously.10–12 It is conjectural whether preoperative bevacizumab injection would have circumvented this difficulty.

The appearance of the fundus 2 days after surgery is shown in Fig. 16.2. Unrecognized preoperatively, but apparent intraoperatively, there was