Effect of panretinal photocoagulation versus intravitreal bevacizumab injection on optic disc microcirculation in patients with diabetic retinopathy.

Background: This retrospective study aimed to compare optic disc vasculature changes in 1 and 3 months after treatment with either panretinal photocoagulation (PRP) or Intravitreal bevacizumab (IVB) in patients with diabetic retinopathy.

Methods: A total of 50 eyes of 29 diabetic patients without severe complications were included in this comparative case series. Of these, twenty-eight eyes (15 patients) were assigned to the PRP group, while twenty-two eyes (14 patients) were treated with the biosimilar (IVB) (Stivant^® CinnaGen Co., Iran). Optical tomography angiography (OCTA) was performed to measure optic disc vascular density (VD) as well as retinal nerve fiber layer (RNFL) thickness.

Results: The mean age of the enrolled patients was 62.1 ± 8.3 years (40 to 78 years). During follow-up, whole disc VD, inside disc VD and peripapillary VD decreased significantly in the PRP group at month 1 (p = 0.032, p = 0.32, and p = 0.016, respectively) and month 3 (p = 0.004, p = 0.001 and p = 0.011, respectively). There was an insignificant and slight increase for these parameters in the IVB group. (p > 0.05 for all) A comparison of two treatment arms based on mean whole disc VD, inside disc VD, and peripapillary VD changes revealed a significant difference at month 1 (p = 0.009, p = 0.019, and p = 0.002, respectively) and month 3 (p = 0.002, p = 0.015, and p = 0.009, respectively). Peripapillary RNFL thickness increased in the PRP group at month 1 (p = 0.002) and then decreased at month 3 (p = 0.001). During three months of follow-up, the peripapillary RNFL thickness decreased significantly in the IVB group (p = 0.001). Peripapillary RNFL thickness changes were significantly different between treatment groups at month 1 and month 3. (p = 0.001 for both) The RNFL changes during the study did not significantly correlate with peripapillary VD changes in each group (p = 0.231 and p = 372, for PRP and IVB group, respectively).

Conclusion: This study demonstrated that IVB and PRP treatments produced distinct short-term microvascular changes in the optic nerve of diabetic retinopathy patients. PRP treatment significantly reduced vascular density in the optic disc and peripapillary region over 3 months, with an initial increase in RNFL thickness followed by a decrease by month 3. In contrast, IVB treatment led to a slight increase in optic disc vascular density while significantly reducing RNFL thickness. No significant correlation was found between changes in RNFL thickness and peripapillary vascular density within either treatment group.