Understanding the risks, and preventive strategies to maximise cataract surgery outcomes for patients with diabetes
Francesco Bandello MD
Careful preoperative planning can help to reduce complications in cataract patients with diabetes, and can help deal with those problems if they do occur, said Francesco Bandello MD, FEBO at the XXXIV Congress of the ESCRS in Copenhagen, Denmark.
Diabetes is a risk factor for cataract and is associated with ocular comorbidities that can predispose to complications and compromise cataract surgery outcomes.
Particularly critical is the need to accurately stage and treat any existing diabetic eye disease because the status of these conditions strongly predicts visual outcomes after cataract surgery, he stressed.
“There is no clear evidence that phacoemulsification causes diabetic retinopathy (DR) or diabetic macular oedema (DME), or that it exacerbates these conditions if they are well controlled,” said Dr Bandello, Professor of Ophthalmology, University Vita-Salute, Milan, Italy.
“However, clinically significant DME or proliferative diabetic retinopathy (PDR) should be stabilised before cataract surgery to reduce the risk for their acceleration,” he added.
Accurate staging requires a comprehensive ophthalmologic examination, which should include optical coherence tomography and possibly fluorescein angiography and standardised echography. Treatment options for PDR include panretinal photocoagulation (PRP) and/or anti-vascular endothelial growth factor (anti-VEGF) therapy. “From the DRCR.net Protocol S, however, we know that anti-VEGF therapy is better than PRP for stabilising and improving visual acuity in eyes with PDR. Panretinal cryopexy and phacoemulsification combined with vitrectomy and endolaser photocoagulation may be considered in selected cases,” said Dr Bandello.
Therapeutic options for DME include anti-VEGF agents, corticosteroids, and various laser approaches, used as either monotherapy or in combination. Based on safety issues, Dr Bandello recommended using an anti-VEGF agent as first-line intervention in patients with glaucoma and for those with a low cardiovascular risk profile and no recent history of cardiovascular events.
A corticosteroid, however, would be preferred in patients with an elevated risk for cardiovascular events, history of vitrectomy, a poor response to previous anti-VEGF therapy, or expected poor compliance with repeat injections.
Preoperatively, patients should also be evaluated and treated for diabetic keratopathy as its presence can affect the accuracy of intraocular lens (IOL) power calculations. In addition, there are special considerations for IOL selection.
“It is best to choose an IOL with a large diameter, square-edge, blue-light filtering optic, as such a lens will facilitate visualisation and treatment of the peripheral retina, reduce posterior capsular opacification, not cause chromatic discrimination defects, and provide additional photoprotection. In addition, hydrophilic IOLs and anterior chamber IOLs should be avoided,” said Dr Bandello.
Poorly dilating pupils and intraoperative miosis are also more likely in patients with diabetes, so surgeons should be prepared to manage these problems. In addition, they should be prepared for zonular instability or capsule damage in eyes with previous vitreoretinal surgery.
Since eyes with moderate-to-severe DR and/or DME are at risk for persistent macular oedema or DR progression after cataract surgery, and considering that diabetic DME is the most common cause of poor vision after cataract surgery, Dr Bandello suggested that surgeons consider intravitreal administration of an anti-VEGF agent or corticosteroid intraoperatively to control and prevent progression of these conditions.
“VEGF concentrations in the aqueous humour predict the risk of postoperative macular oedema and tend to increase after phacoemulsification. Although results from a large randomised controlled trial are needed to provide evidence-based recommendations, positive clinical outcomes have been reported in several studies where patients with diabetes received intravitreal injection of an anti-VEGF agent at the end of cataract surgery.”
Based on their multimodal mechanism of action, corticosteroids can also play an important therapeutic role in the management of DME. There are also reports of improvements in best corrected visual acuity and central macular thickness when eyes with DME receive the sustained-release dexamethasone implant (Ozurdex, Allergan) during cataract surgery. However, a larger prospective randomised controlled trial is also needed to establish the benefits of this approach, Dr Bandello said.
He also noted that patients with diabetes are at increased risk for developing cystoid macular oedema after cataract surgery.
Francesco Bandello: firstname.lastname@example.org