Abstract
Purpose :
Active retinal neovascularization in proliferative diabetic retinopathy (PDR) often leads to vitreous hemorrhage, and increases the difficulty of vitrectomy. It is well known clinically that pan-retinal photocoagulation (PRP) and intravitreal bevacizumab can cause regression of retinal neovascularization to fibro-vascular membrane (FVM). This study seeks to examine and compare the effects of PRP and intravitreal bevacizumab on FVM regression.
Methods :
Patients requiring vitrectomy for PDR with FVM were recruited. Patients were stratified with preoperative intravitreal bevacizumab, PRP, or both bevacizumab and PRP treatments. FVM tissues were obtained during vitrectomy and processed for immune-histochemical staining with Collagen IV and Vimentin to label vessels and fibrosis, respectively. Vascular and fibrosis areas were then quantified and compared over the total area of the tissue. A FVM maturity score was determined by the ratio of fibrotic area over the vascular area. Scores of more than 1 suggest more fibrosis than vessels, whereas scores less than 1 correlate with more vessels than fibrosis.
Results :
In 6 FVM specimens from 6 eyes, all had preoperative PRP 5 to 7 weeks before vitrectomy. Three patients who also received 1 week to 9 months preoperative intravitreal bevacizumab had larger vascular (6.77%) and less fibrotic (4.08%) areas with a mean FVM maturity score of 0.60. The other 3 cases with no preoperative intravitreal bevacizumab had fewer vascular (6.51%) and more fibrotic areas (15.11%) with a much greater mean FVM maturity score of 2.32. The numbers of preoperative PRP were 2.3 times in PRP alone group, and 3 times in PRP plus bevacizumab group. Two specimens were obtained from 2 eyes of the same patient. The FVM from the eye with intravitreal bevacizumab was less mature (maturity score of 0.62), compared with the fellow eye without bevacizumab (maturity score of 1.12).
Conclusions :
Our studies show that the FVM specimens from PDR patients with both preoperative PRP and bevacizumab have less FVM regression than those treated with preoperative PRP alone. This suggests that intravitreal bevacizumab does not have lasting effect, if any, on FVM regression, and thorough PRP treatment alone can result in good FVM regression in PDR.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.