Sir,

We read with interest Mansour et al's1 paper highlighting the risk of anterior ischaemic optic neuropathy (AION) in diabetics after coronary artery bypass graft (CABG) surgery. We present a diabetic patient who suffered significant loss of vision owing to rapid progression of retinal ischaemia following CABG.

A 58-year-old man was diagnosed with mild non-proliferative diabetic retinopathy (NPDR) in October 2002. His vision was 6/6 in both eyes. In July 2004, his vision decreased to 6/18 in the right eye and 6/9 in the left eye. A fundus fluorescein angiogram (FFA) detected ischaemic maculopathy in both eyes (Figure 1.) Six months later he developed new vessels in the left eye and had two sessions of panretinal photocoagulation. His vision at this stage was 6/12 in both eyes. Two months later he underwent a three-vessel CABG. The preoperative haematocrit was 0.432. Postoperatively the lowest haematocrit was 0.164. The patient received one unit of packed red blood cells. The surgery and postoperative period was uncomplicated. Six weeks following the surgery his vision reduced to 6/60 in his right eye and 6/24 in left eye. Clinically the right eye had severe NPDR. The left eye showed new vessels at the disc. Both discs were healthy. FFA showed large areas of capillary dropout and increased macular ischaemia (Figure 2). Two months later his right eye developed rubeotic glaucoma causing the vision to drop to hand movements. Since then he has had extensive panretinal photocoagulation in both eyes and cycloablation of the ciliary body in the right eye. At present he has no perception of light in the right eye and hand movements in the left.

Figure 1
figure 1

FFA of the left eye showing ischaemic maculopathy.

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Figure 2
figure 2

FFA of the left eye after CABG showing a significant increase in ischaemia. New vessels are also present at the disc.

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The retinal ischaemia in this patient was probably precipitated following CABG. It may be argued that his retinopathy was progressing preoperatively and may have followed a similar course irrespective of the cardiac surgery. However, we believe that the decreased tissue perfusion and postoperative anaemia resulting from the CABG accelerated the progression of his retinal vascular disease. Anaemia is a well-known risk factor for progression of diabetic retinopathy2 and is likely following aggressive haemodilution for CABG. This case highlights the risk of such a procedure to diabetic retinopathy. Such high-risk eyes should undergo extensive panretinal photocoagulation before any procedure necessitating general anaesthesia or anticoagulation. As with AION,1 aggressive anaemia therapy may well prove to be beneficial in slowing progression of retinal ischaemia in diabetics undergoing CABG.