ICO guidelines for diabetic eye care
1. Optimize medical treatment.
2. No diabetic retinopathy, mild or moderate non-proliferative diabetic
3. Severe non-proliferative diabetic retinopathy
4. Proliferative diabetic retinopathy
Key learning points
Treating proliferative diabetic retinopathy
The two main treatment options for proliferative diabetic retinopathy are panretinal laser photocoagulation and diabetic vitrectomy.
Pan-retinal photocoagulation (PRP)
PRP, or scatter laser, is the main form of treatment for proliferative diabetic
retinopathy. The aim of the laser is to induce regression of new blood vessels (that is, to make them stop growing and shrink). The laser burns must be given early enough and cover enough retina to shrink the new blood vessels that cause the complications of vitreous haemorrhage and tractional (due to a pulling action) detachment of the retina.
A 50% reduction in severe visual loss after PRP was reported by the Diabetic Retinopathy Study for patients with new vessels on the optic disc (proliferative diabetic retinopathy).
Pre-treatment discussion with patients (ICO, 2017)
Vitrectomy is indicated in proliferative diabetic retinopathy in the following
Currently, vitrectomy for diabetic macular oedema is reserved for the few patients who have vitreous traction on the macula. The technique is an important part of the treatment of proliferative diabetic retinopathy and leads to improvement or stabilisation of vision in 90% of patients.
Vitreous and blood are cut and aspirated and membranes causing tractional
a detachment of the retina is removed. The results are often poor for long-standing tractional retinal detachments of the macula. In a resource-poor environment, those with a better prognosis should be prioritised. It is worth pre-treating patients with intravitreal bevacizumab (a type of anti-VEGF) prior to vitrectomy.
A Cochrane review of six randomised controlled trials found that pre-treatment intravitreal bevacizumab resulted in shorter operations with bleeding during the operation. Post-operative reabsorption of blood was significantly shorter. Final best-corrected visual acuity was significantly better.
Treating diabetic maculopathy
Diabetic maculopathy is a major cause of vision loss amongst patients with diabetes. Treatment includes steroids, anti-vascular endothelial growth factor (anti-VEGF) and laser.
In the Diabetic Retinopathy Clinical Research Network trial, intravitreal injections of the steroid triamcinolone acetonide (IVTA), was compared with standard laser treatment. Although there were short-term improvements in visual acuity with this steroid, this improvement was not sustained. The laser was more effective and had fewer side effects than IVTA. The side effects of IVTA included cataract formation and raised intraocular pressure. Recently, the same group found that there was one exception, in pseudophakic eyes, IVTA and prompt laser seemed more effective than laser alone.
Vacular endothelial growth factor (VEGF) levels are increased in the vitreous and retina in patients with diabetic retinopathy. The increased level of VEGF stimulates the growth of new blood vessels and increase the risk of haemorrhage and further complications.
Currently, there are four anti-VEGF intravitreal treatment in clinical use: pegaptanib, ranibizumab (Lucentis), bevacizumab (Avastin) and aflibercept.
Anti-VEGF treatment is currently the mainline of treatment for diabetic macular oedema with good visual outcome. However, intravitreal anti-VEGF treatment regime is a challenging one for patients and generates a significant workload for health care providers.
The financial commitments for health systems are also considerable, for example – ranibizumab injections cost around $1,200 each and the patients may require up to eight or nine injections in the first year (a cost of around $10,000 per patient per year).
Intravitreal bevacizumab is much cheaper. In low resource settings, an intravitreal bevacizumab injection can be available for as little as $25.
In practice, laser treatment should remain the cornerstone of treating clinically significant macular oedema and the use of intravitreal injections should be tailored to the needs of individual patients.
The Early Treatment of Diabetic Retinopathy study compared macular laser with observation. There was a 50% reduction in moderate visual loss in the group that received laser (from 24% to 12%).