Intravitreal Ranibizumab Injections Significantly Influence Retinal Venous Calibre in Patients With Diabetic Macular...

To assess changes in retinal vascular calibre following intravitreal ranibizumab treatment in patients with diabetic macular oedema (DMO).

A post hoc analysis of data from a prospective clinical study assessing patients treated with ranibizumab for DMO was conducted. 76 eyes of 67 treatment naive patients were recruited. Patients received three, monthly, ranibizumab injections. From months 3 to 12, ranibizumab injections were administered PRN. Retinal vascular calibre was measured from digital fundus photographs with a semiautomated computer programme (SIVA) and summarised as central retinal artery (CRAE) and vein (CRVE) equivalent. Artery to vein ratio (AVR) was derived from CRAE/CRVE. The primary and secondary outcomes were change in CRAE, CRVE, AVR, CMT and BCVA from baseline to month 2 and 12, respectively.

BCVA improved significantly from 60.71 ± 8.24 letters by 6.76 ± 6.40 (P < 0.001) at month 2 and 10.12 ± 10.86 (P < .001) at 12. CMT, 470.58 μm ± 106.91 μm, significantly reduced by 81.41 μm ± 99.73 μm (P  < 0.001) at month 2 and 132.48 ± 141.79 μm (P < 0.001) at month 12. There was a statistically significant CRVE decrease by -8.44 μm ± 11.27 μm (P < 0.0001) at month 2 and -4.68 ± 12.41 μm (P = 0.03) at month 12, whilst AVR increased by +0.02 μm ± 0.04 μm (P = 0.02) at month 2 and +0.02 μm ± 0.04 μm (P = 0.01) at month 12.

Ranibizumab treatment was associated with a significant reduction in CRVE and increase in AVR. It is possible that the positive effect of ranibizumab therapy on improvements in BCVA and CMT may be related to reduction of retinal venous calibre and hydrostatic pressure.