Complications of Surgery for Diabetic Retinopathy

RETINA SURGERY FEATURE STORY Complications of Surgery for Diabetic Retinopathy

BY TOM H WILLIAMSON, MD, MBCHB, FRCS, FRCOPHTH

lthough diabetic retinopathy was one of the first conditions for which pars plana vitrecto- For reasons that are not clearly my (PPV) was employed, vitreoretinal sur- A gery for complications of diabetes remains a understood, patients with diabetes challenge. In general, success rates for visual improve- are less likely to develop cataracts ment are 90% for vitreous hemorrhage, 60% for those post-vitrectomy. with tractional retinal detachment and may be as low as 30% to 40% for those with combined tractional and rhegmatogenous retinal detachment. Much of this less likely to develop cataracts post-vitrectomy. Thus, reduction in success rate is due to the underlying con- for these patients a combined vitrectomy/phacoemulsi- dition of diabetic retinopathy with ischemia and cys- fication procedure is unnecessary. It has been postulat- toid macular edema (CME) implicated in poor visual ed that cataracts do not form in these patients because recovery however surgical complications also con- of reduced oxidative stress on the lens proteins in the tribute.1 Complications for surgery can be divided into ischemic diabetic eye.2 Performing vitrectomy increases

preoperative complications and postoperative compli- the partial oxygen pressure (PO2) in the vitreous. It is cations but the two are inter-linked. It is therefore easi- possible that the vitreous functions to keep oxygen ten- er to consider the eye from its anterior segment to pos- sion low around the lens, and that this reduces the terior segment. oxidative stress on the lens fibers.3 In ischemic eyes,

such as in patients with diabetes, the PO2 is lower—and ANTERIOR SEGMENT COMPLICATIONS remains lower than normal—even after vitrectomy. For Commencing with the cornea, these patients have a this reason, the diabetic eye may be protected from loose corneal epithelium that is prone to separation. postoperative cataract. The reduced performance of The surgical use of a contact lens system for visualiza- combined cataract and vitrectomy surgery in these tion of the retina in prolonged surgery may cause patients translates to a risk of lens touch, in my series corneal edema, reducing the surgeon’s ability to view 1.3% in these patients. the retina. In such cases, debridement of the epithelium is performed to clear the cornea. The more frequent use POSTERIOR SEGMENT COMPLICATIONS of noncontact visualization systems, however, has signif- Early Vitreous Hemorrhage icantly reduced the need to remove the corneal epithe- Postoperative vitreous hemorrhage in these patients lium during surgery. can be divided into early (within 2 months of surgery) Cataract after vitrectomy is common, particularly in and late.4-6 Early hemorrhage can be present in up to patients older than 50 years. For reasons that are not 60% of patients in the postoperative period. Surgical clearly understood, however, patients with diabetes are technique is important; dissection of neovascular mem-

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ate to trim the blood clot down to the bleeding point leaving a small piece of clot at the blood vessel to maintain the plugging effect of the thrombus. Other strategies have been described to deal with perioperative bleeding such as heparin infusion into the eye to prevent clot- ting and allow washout of any bleeding. In addition, some surgeons have described inserting adrenaline into the infusion bottle, although this carries a distinct risk of shutting down vessels.

Late Vitreous Hemorrhage Late vitreous hemorrhage occurs in 12% to 27% of patients treated for diabetic retinopathy; I warn my Figure 1. Applying pressure to a bleeding vessel. patients that there is a 10% chance of a repeat vitrectomy for removal branes can cause preoperative hemorrhage, which of postoperative blood. It is worth informing your reduces the ability of the surgeon to perform further patient that over the long term—1 year to 18 months— membranectomy (reduces the view and fibrin adheres some patients will experience small bleeds which last a to retina). In very rare cases bleeding can be uncontrol- few a days at a time. Gradually, these reduce with fre- lable leading to risk of abandonment of surgery. In order quency; however, a few may require a further vitrecto- to control bleeding during diabetic surgery I recom- my. More laser therapy can be applied and is usually mend the following: enough to prevent further bleeding. • Elevate the infusion bottle to try to minimize the bleed from vessels but to watch the optic nerve which Sclerotomy Site Neovascularization has a fragile circulation and is prone to shut down with There are a number of descriptions of sclerotomy site raised intraocular pressure. neovascularization in these patients. This remains a • Apply pressure to the bleeding point with a blunt controversial topic as a potential cause of late postoper- instrument such as a flute needle tip. The pressure must ative bleeding. Some surgeons will perform dissection be applied for enough time to allow the blood to clot of the sclerotomy site neovascularization in an attempt (Figure 1). Perioperatively, this may seem like a very long to reduce further bleeding. These patients, however, are time as the instrument must be kept still on the blood also having repeat vitrectomy and more laser applica- vessel to avoid tearing of the retina. I generally suggest a tion—I personally find this is enough to prevent further 1-minute minimum application of pressure to allow the bleeds without specific dissection of the sclerotomy hole in the blood vessel to plug. sites.7-9 Other types of potential hemorrhage in this • Endodiathermy can be applied; technically it has a kind of surgery remain very low. In my series of 264 trac- tendency to damage the retina in the area of applica- tional retinal detachments I had no choroidal hemor- tion. Removal of the endodiathermy tip can be associat- rhages, small or large. ed with removal of the plug of fibrin causing a recur- rence of bleeding. Thus, I use do not use endo- Iatrogenic Breaks diathermy frequently. Iatrogenic breaks are common in patients receiving Once a clot has been formed, it can become very delamination surgery with en bloc dissection of neovas- adherent to the fragile diabetic retina. It may be tempt- cular membranes, caused by traction on membranes, ing to aspirate the clot and pull if off the bleeding direct incision of the retina from scissors or cutters or blood vessel. This removes the plug of fibrin, however, insertion of instruments into sclerotomy entry sites.10-12 which allows hemostasis. It is therefore more appropri- Some patients have schitic retina from traction from

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close to the break must be removed, as traction of the membrane on the breakage postoperatively will cause lifting and retinal detachment. Instead, flatten the break, laser, and tamponade with intraocular gas.

Rhegmatogenous Retinal Detachment Rhegmatogenous retinal detachment postoperatively can occur despite panretinal photocoagulation and multiple laser scars.4,13,14 Retinal detachment rates have been described in 1% to 9% of patients. These patients usually have iris neovascularization (83%).15,16 The surgeon should reoperate as quickly as possible because proliferative vitreo- Figure 2.This patient had a peripheral giant retinal tear causing retinal detachment retinopathy (PVR) occurs rapidly after vitrectomy which remained peripheral due to pre existing PRP. and can lead to an inoperable situa- tion. In a patient who develops this complication without PVR, vitrectomy and gas can be performed. However more often, PVR has been initiated Silicone oil remains a risky agent to use and the patient will require vitrectomy and oil. In gener- in a diabetic eye and should only be al, silicone oil is not ideal for use in a diabetic eye and I prefer to never use it as a first-line tamponade in these used when absolutely necessary. patients.17-19 It is impenetrable to oxygen and may exac- erbate the ischemic condition.20 It appears to be associ- ated with enlargement of retinal breaks, proliferation of neovascular membranes—a feature that is prone to reti- membranes, and a high risk of subretinal silicone oil if nal breaks during delamination (Figure 2). used at the first surgery. It may however, be necessary to insert at subsequent surgery if the patient’s eye is com- Segmentation or En Bloc plicated by retinal detachment. The risk of these cata- Originally, segmentation of difficult-to-remove mem- strophic outcomes with silicone oil appears to be lower branes was performed. It was then determined, howev- at the second surgery, possibly because the laser has had er, that it would be more advantageous to remove all a chance to reduce the relative ischemia of the retina. membranes from the retina, i.e, en bloc dissection. One Silicone oil remains a risky agent, however, to use in a school of thought suggests complete removal of mem- diabetic eye and should only be used when absolutely branes, dealing with the consequences of any iatrogenic necessary. Maneuvers, such as retinectomy in these eyes, breaks that are created afterward. The other school sug- are fraught with risk but may sometimes be necessary if gests segmentation of membranes too difficult to the retina will not reattach with tamponade alone. remove in an attempt to reduce the iatrogenic break Much remains that we do not know about the rate. The described rates of breaks vary from 20% to response of the diabetic eye to surgery. In simple cases 35% and in my practice, I choose to create the iatro- of vitreous hemorrhage, success rates are high but in genic break and deal with it rather than leave mem- patients with tractional retinal detachment, with dissec- brane behind on the retina. Persistent membrane may tion off the delicate retina and optic nerve, there may cause reproliferation of the membrane and further trac- be residual effects on the retina that we as yet cannot tion on the retina. If the membrane is close to the disc quantify. Often a good surgical result is not followed by or the macula, contraction causes striae in the macula, a good visual result. Optic atrophy is commonly seen reducing vision. Once a break is created, the membrane and the retina is often thin.

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PREOPERATIVE MEASURES 3. Williamson TH, Grewal J, Gupta B, et al. Measurement of PO2 during vitrectomy for cen- tral retinal vein occlusion, a pilot study. Graefes Arch Clin Exp Ophthalmol. Intravitreal antivascular endothelial growth factor 2009;247(8):1019–1023. agents (anti-VEGF), such as bevacizumab (Avastin, 4. Brown GC, Tasman WS, Benson WE, et al. Reoperation following diabetic vitrectomy. Genentech, Inc.), have been successfully used preopera- Arch Ophthalmol. 1992;110(4):506–510. 5. Novak MA, Rice TA, Michels RG, Auer C. Vitreous hemorrhage after vitrectomy for dia- tively to reduce perioperative complications, such as peri- betic retinopathy. Ophthalmology. 1984;91(12):1485–1489. 21 operative bleeding, in tractional retinal detachments. 6. Tolentino FI, Cajita VN, Gancayco T, Skates S. Vitreous hemorrhage after closed vitrec- Injected 1 week before tractional retinal detachment sur- tomy for proliferative diabetic retinopathy. Ophthalmology. 1989;96(10):1495–1500. gery, anti-VEGF agents can reduce the blood flow in 7. West JF, Gregor ZJ. Fibrovascular ingrowth and recurrent hemorrhage following diabetic vitrectomy. Br J Ophthalmol. 2000;84(8):822–825. membranes and contraction of the membrane. 8. Sawa H, Ikeda T, Matsumoto Y, et al. Neovascularization from scleral wound as cause of Surgical innovations include the development of vitreous rebleeding after vitrectomy for proliferative diabetic retinopathy. Jpn.J Ophthalmol. high-speed cutters with cutting orifices that are nearer 2000;44(2):154–160. 9. Lewis H, Abrams GW, Williams GA. Anterior hyaloidal fibrovascular proliferation after dia- the end of the cutter tip. These may allow closer dissec- betic vitrectomy. Am J Ophthalmol. 1987;104(6):607–613. tion of membranes from the retina, and may reduce the 10. Abrams GW, Williams GA. “En bloc” excision of diabetic membranes. Am J Ophthalmol. need for scissor-delamination prior to the removal of 1987;103(3 Pt 1):302–308. 11. Carter JB, Michels RG, Glaser BM, de BS. Iatrogenic retinal breaks complicating pars the membranes. Surgery for very complex tractional plana vitrectomy. Ophthalmology. 1990;97(7):848–853. retinal detachments and those with rhegmatogenous 12. Oyakawa RT, Schachat AP, Michels RG, Rice TA. Complications of vitreous surgery for retinal detachment can be aided by surgery with a diabetic retinopathy. I. Intraoperative complications. Ophthalmology. 1983;90(5):517–521. 13. Virata SR, Kylstra JA. Postoperative complications following vitrectomy for proliferative bimanual approach. The use of chandelier illumination diabetic retinopathy with sew-on and noncontact wide-angle viewing lenses. Ophthalmic systems allows the surgeon to use forceps in one hand Surg Lasers. 2001;32(3):193–197. and scissors in the other to remove membranes from 14. Wand M, Madigan JC, Gaudio AR, Sorokanich S. Neovascular glaucoma following pars plana vitrectomy for complications of diabetic retinopathy. Ophthalmic Surg. mobile retina, hopefully reducing iatrogenic tear forma- 1990;21(2):113–118. tion in these complex cases. 15. Kadonosono K, Matsumoto S, Uchio E, et al. Iris neovascularization after vitrectomy The catastrophe rate in these patients is 3% to 4% for combined with phacoemulsification and intraocular lens implantation for proliferative diabetic retinopathy. Ophthalmic Surg Lasers. 2001;32(1):19–24. phthisis bulbi and 7% for risk of no perception of light 16. Helbig H, Kellner U, Bornfeld N, Foerster MH. Rubeosis iridis after vitrectomy for diabetic 4,22 in some series. The risk of no perception of light is retinopathy. Graefes Arch Clin Exp Ophthalmol. 1998;236(10):730–733. increased in those who have iris neovascularization, 17. Pearson RV, McLeod D, Gregor ZJ. Removal of silicone oil following diabetic vitrectomy. Br J Ophthalmol. 1993;77(4):204–207. postoperative hemorrhage and macular ischemia. 18. Heimann K, Dahl B, Dimopoulos S, Lemmen KD. Pars plana vitrectomy and silicone oil These patients with often severe diabetic complications injection in proliferative diabetic retinopathy. Graefes Arch Clin Exp Ophthalmol. systemically have a reduced 5 year survival to some- 1989;227(2):152–156. where between 68% and 80%.23-25 19. Wilson-Holt N, Gregor Z. Spontaneous relieving retinotomies in diabetic silicone filled eyes. Eye. 1992;6 (Pt 5):461–464. In conclusion, vitrectomy for complications of diabet- 20. de Juan E, Jr., Hardy M, Hatchell DL, Hatchell MC. The effect of intraocular silicone oil ic retinopathy is complex surgery. Although cataract on anterior chamber oxygen pressure in cats. Arch Ophthalmol. 1986;104(7):1063–1064. formation is reduced postoperatively this is replaced by 21. Gandhi JS, Tan LT, Pearce I, Charles SJ. Bevacizumab (Avastin) as a surgical adjunct in diabetic vitrectomy for fibrovascular disease. Eye. 2008;23(3):742–743. Epub 2008 Apr 11. an increased rate of postoperative vitreous hemorrhage 22. Oldendoerp J, Spitznas M. Factors influencing the results of vitreous surgery in diabetic and iatrogenic tear formation, especially in patients retinopathy. I. Iris rubeosis and/or active neovascularization at the fundus. Graefes Arch Clin with traction retinal detachment. If patients develop Exp Ophthalmol. 1989;227(1):1–8. 23. Gollamudi SR, Smiddy WE, Schachat AP, et al. Long-term survival rate after vitreous sur- retinal detachment postoperatively iris neovasculariza- gery for complications of diabetic retinopathy. Ophthalmology. 1991;98(1):18–22. tion is common. ■ 24. Summanen P, Karhunen U, Laatikainen L. Characteristics and survival of diabetic patients undergoing vitreous surgery. Acta Ophthalmol. (Copenh). 1987;65(2):197–202. 25. Helbig H, Kellner U, Bornfeld N, Foerster MH. Life expectancy of diabetic patients under- Tom H. Williamson, MD, MBChB, FRCS, going vitreous surgery. Br J Ophthalmol. 1996;80(7):640–643. FRCOphth, MD, is a Senior Consultant SHARE YOUR FEEDBACK Ophthalmologist at St. Thomas’ Hospital, London, Queen Mary’s Hospital, Sidcup, Kent, and is an Would you like to comment on an author’s article? Honorary Clinical Lecturer at King’s College, Do you have an article topic to suggest? London. Dr. Williamson states that he has no financial rela- tionships to disclose. He can be reached at +1 44 207 188 Do you wish to tell us how valuable 4320; or via e-mail at [email protected]. Retina Today is to your practice? We would love to hear from you. Please e-mail us at 1. Yorston D, Wickham L, Benson S, et al. Predictive clinical features and outcomes of vitrectomy for proliferative diabetic retinopathy. Br J Ophthalmol. 2008;92(3):365–368. [email protected] with any thoughts, feelings, 2. Holekamp NM, Shui YB, Beebe D. Lower intraocular oxygen tension in diabetic patients: possible contribution to decreased incidence of nuclear sclerotic cataract. Am J Ophthalmol. or questions you have regarding this publication. 2006;141(6):1027–1032.

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