Sub-Tenon anaesthesia: reduction in subconjunctival haemorrhage with controlled bipolar conjunctival cautery

To evaluate the effect of controlled conjunctival cautery on the frequency and extent of subconjunctival haemorrhage (SCH) associated with sub-Tenon anaesthetic (STA) injection in patients with various clotting states.

One hundred forty-four patients suitable for cataract surgery with STA were prospectively divided into four groups: group A (n=36) were on warfarin (INR 1.8-4.2); group B (n=48) on aspirin (75 mg); group C (n=12) on clopidogrel (75 mg); and group D (n=48) on no anticoagulant or antiplatelet agents. All patients had no other known coagulopathy. Each group was randomly divided into two subgroups, one of which received localised bipolar cautery under microscope control to the STA conjunctival entry site before tissue dissection, whereas the other served as a control. chi(2) and Fisher's exact tests were used to analyse the data with the SPSS package (v11.0).

Conjunctival cautery reduced the frequency of SCH from 67 to 6% in group A (P=0.0001); from 37.5 to 4% in group B (P=0.005); from 50 to 0% in group C (P=0.9); and from 17 to 0% in group D (P=0.55). This overall reduction in SCH was highly significant (P<0.0001), especially in groups A and B. No statistically significant reduction in the extent of SCH was found.

Controlled localised bipolar conjunctival cautery before STA injection may significantly reduce the frequency of SCH, especially in patients on warfarin or aspirin.