People with diabetes can avoid early worsening of retinopathy that occurs after intensive glycaemic control if at-risk individuals are identified in advance, ophthalmologists say.
Regular retinal examinations and the use of anti-VEGF therapies such as bevacizumab can help avoid and ameliorate the worsening of diabetic retinopathy and vision loss experienced by some patients immediately after they have substantial reductions in glycaemia, according to Dr Shueh Wen Lim and colleagues at the Royal Victorian Eye and Ear Hospital in Melbourne.
While tight glycaemic control has favourable long-term effects on the risk of diabetic retinopathy, early worsening is a recognised problem for some patients such as those who have sudden reductions in blood glucose levels after undergoing bariatric weight loss surgery, they write in Clinical Experimental Ophthalmology.
Early worsening is a particular problem for patients with a long history of poorly-controlled diabetes and those with established advanced diabetic retinopathy, they say. The mechanism for early worsening of retinopathy is not clear but it may involve upregulation of IGF-1, impairment of retinal circulation autoregulation and decreased availability of cellular energy substrates after intensive glycaemic control is started, they suggest.
The clinicians cite examples of two patients in their own practice who experienced early worsening of retinopathy, but which responded to anti-VEGF treatment.
In one case, a 52-year old man with newly-diagnosed type 2 diabetes showed significant deterioration of his pre-existing diabetic retinopathy in the five months after he started oral hypoglycaemic agents and insulin and his HbA1c levels reduced from 16% to 6.9%.
With gross diabetic macular oedema and visual acuity reduced in both eyes, the man was treated with monthly intravitreal bevacizumab injections. Six months later his visual acuity had improved and the DMO showed significant improvement.
In a second case, a 54-year old man with poorly controlled T2D was able to avoid early worsening of diabetic retinopathy by having bevacizumab injections when his HbA1c levels reduced from 9.1% to 5.3% within three months. The anti-VEGF treatment was associated with stabilisation of retinopathy, resolution of DMO and improvement in visual acuity.
The authors of the report note that in studies of intensive glycaemic control such as DCCT about half of patients with early worsening of retinopathy recovered within six-12 months. In patients undergoing bariatric surgery up to 45% with diabetic retinopathy experienced worsening in the first year after the procedure, but other reports showed only 5% of patients had persistent worsening.
They recommend identification of high-risk individuals before intensive therapy is initiated and retinal examination at least every three months over the first year
“Forewarning of the potential for worsening of retinopathy should be given to people in whom the intensification of glycaemic control is considered, and regular ophthalmological review is advised in high risk individuals,” they conclude.