RETINOPATHY

The proper grading of the vitreoretinal attachments is a very important part of the preoperative evaluation of proliferative diabetic retinopathy, said Borja Corcostegui MD in a discussion of trends in the surgical treatment of diabetic retinopathy presented at the 12th EURETINA Congress. It is particularly important because there is a correlation between the vitreal retinal attachments and the surgical outcome, explained Dr Corcostegui of the Institut Microcirurgia Ocular, Barcelona, Spain.

Dr Corcostegui outlined the grading scale for vitreoretinal attachments in eyes undergoing vitrectomy for proliferative diabetic retinopathy. This is a scale from Type 0 to 6. Type 0 refers to a complete PVD. Type 1 has focal vitreoretinal attachment(s). Type 2 has broad vitreoretinal attachments. Type 3 has vitreous attachment at the entire posterior pole, including the optic disc, vascular arcades and macula. Type 4 has attachments at the disc and arcades extending to the periphery, but with no vitreoretinal adhesions at the macula. Type 5 refers to complete vitreoretinal attachment. The fewer adhesions exist, the better the surgical outcome on average, and the wider the surgical indication.

So, for Type 0, surgery would be indicated for a non-clearing vitreous haemorrhage. Complications are unlikely in Types 0 and 1. In Type 2, surgical complications occur in approximately five per cent of cases, increasing to seven per cent in Type 3 and up to 12 per cent in Type 4. The increased rate of complications is related to the need for extended dissections. Clinical indication for surgery in Type 4 might be, for example, a premacular subhyaloid haemorrhage. Type 5, which is frequently associated with retinal detachment due to proliferation and contraction, is associated with up to a 20 per cent surgical complication rate. In order to decrease the chances of complications, Dr Corcostegui recommends preoperative preparation of the posterior segment. This includes anti-VEGF treatment and the completion of panretinal photocoagulation as much as possible.

“We inject Avastin or Lucentis four to seven days preoperatively to decrease proliferative neovascularisation, shrink collagen tissue and decrease the calibre of retinal vessels. However, anti-VEGF, while effective for reducing perioperative bleeding, has low efficacy on vitreoretinal adhesions. Fortunately, the newer instrumentation makes the surgery safer and easier,†said Dr Corcostegui. At the same session Dr Albert J Augustin, professor and chairman of the Department of Ophthalmology, Klinikum Karlsruhe, Karlsruhe, Germany, presented an indepth review of the literature regarding the surgical management of the complications of proliferative diabetic retinopathy. He began by listing the major complications of proliferative diabetic retinopathy. These include rubeosis and neovascular glaucoma; tractional retinal detachment; non-clearing vitreous haemorrhage; and macular disorders. “Surgical management of proliferative diabetic retinopathy has improved substantially, and anti-VEGF drugs and steroids are helpful adjuncts,†said Dr Augustin.

A 2011 study of the effect of intracameral Avastin for iris rubeosis and neovascular glaucoma in proliferative diabetic retinopathy showed a decrease in IOP and stable or improved visual acuity at six months. Dr Augustin then reviewed a 2011 longterm study (mean follow-up: 23 months) of vitrectomy without endotamponade for tractional retinal detachment. The retina remained anatomically attached in 94 per cent of all eyes. This suggests that endotamponade is not necessary if there are no pre- or intraoperative retinal breaks. The DRIVE UK Study, published in 2012, studied visual and anatomical outcomes following vitrectomy for proliferative diabetic retinopathy. This study showed a much greater improvement in visual acuity when the surgical indication was non-clearing vitreal haemorrhage alone rather than in combination with tractional retinal detachment, which seems reasonable considering the large difference in severity of the pathology.

One study compared the outcomes of treatment for tractional retinal detachment using microincision vitrectomy and bevacizumab (2005-2007) with outcomes of conventional 20G vitrectomy without anti- VEGF therapy (2003-2005). Although the ultimate anatomic success was 100 per cent in both study arms, improvement in visual acuity at six months post-op was better in the microincision vitrectomy + bevacizumab group than in those treated with 20G. “Was this due to the effect of the smallgauge surgery, or the anti-VEGF effect, or both? Or maybe due to an improvement in surgical technique and performance?†asked Dr Augustin. “That’s a difficult question to answer and it highlights the problems with retrospective studies.â€

Later studies have shown that 23G vitrectomy is as effective as 20G, and that preoperative intravitreal bevacizumab simplifies the surgical procedure in dense diabetic vitreal haemorrhage. Further, early vitrectomy and endolaser for severe vitreal haemorrhage in proliferative diabetic retinopathy is recommended. A 2011 study demonstrated improvement in visual acuity and a stabilisation of proliferative diabetic retinopathy at short- and long-term follow-up. “This same conclusion was drawn from the Diabetic Retinopathy Vitrectomy Study in 1990,†Dr Augustin reminded his listeners. This was a randomised study that included nearly 1000 patients and followed them up for four years after vitrectomy for severe vitreous haemorrhage. When asked by a delegate what his own clinical impression was regarding the two, Dr Augustin responded, “My impression is that 23G is better. Although 23G used to be for selected patients only, it can now be used for essentially all cases, including complex cases. Our surgical performance is so much better than it was 10 years ago.â€