Sildenafil dilates ophthalmic artery in type 2 diabetic patients

BACKGROUND Conflicting reports exist on the effect of sildenafil on ophthalmic artery blood flow; many visual disturbances due to vascular insult were reported with the use of sildenafil in diabetic patients like nonarteritic ischemic optic neuropathy. OBJECTIVES The present work aimed to investigate whether sildenafil modulates ophthalmic artery vasoreactivity in patients with type 2 diabetes mellitus. Literature reports on this aspect are lacking. METHODS A total of 35 male subjects were enrolled in this study, 18 with type 2 diabetes mellitus matched with 17 normal individuals. Ophthalmic artery was insonated through a transorbital window using colored Doppler equipment with transcranial Doppler facility. Ophthalmic artery reactivity was assessed using breath holding/hyperventilation test, before and after giving 50 mg oral sildenafil. RESULTS It was found that in both normal subjects and diabetic patients, sildenafil increased baseline control of mean flow velocity of ophthalmic artery significantly (p < 0.05), breath holding caused a decrease of MFVopa (p < 0.05), and subsequent hyperventilation caused increase of MFVopa (p < 0.05). There was no statistically significant change in breath holding index and full range of vasodilatation of ophthalmic artery (p > 0.05) after sildenafil, in normal and diabetic groups. There was a significant increase of resistive index of ophthalmic artery flow in diabetic patients compared with that of normal subject (p < 0.05). Sildenafil decreased resistive index of ophthalmic artery flow significantly only in diabetic patients (p < 0.05). CONCLUSION Sildenafil increased MFVopa, but had no significant effect on vasoreactivity of ophthalmic artery; sildenafil decreased resistive index only in type 2 diabetic patients.