Effect of pan-retinal photocoagulation on the retinal nerve fiber layer in Diabetic patients

Damage to the retinal nerve fiber layer (RNFL) has been introduced as a possible complication of pan-retinal photocoagulation (PRP). Pallor of the optic disc is often seen in patient with diabetes، but its relationship with PRP has not been proven in a controlled study. Therefore، it is not clear that these findings are the result of diabetes or PRP plays a role. The Present study was to investigate the effect of PRP on RNFL thickness as an indirect indicator of Ganglion cell damage.

This is a before-after study of peripapillary retinal nerve fiber layer (RNFL) thickness in diabetic patients undergoing PRP. RNFL measurements were performed before and 4-6 months after completion of PRP. The relationships between RNFL thickness and the number of laser burns، duration of diabetes and co-existence of hypertension (HTN) were analyzed. Patients with glaucoma and other retinal diseases were excluded from the study.

A total of Forty eyes of 20 patients with a mean age of 54. 6 years (35-70) were recruited، 8 patients (40%) had HTN. Mean duration of diabetes was 12. 6 years. Age، co-existence of HTN and number of laser burns did not have correlation with the NFL thickness before PRP treatment (p>0. 05). Mean NFL thickness was 92. 2±21. 1 before، and 90. 4 ±16. 1، 4-6 months after completion of PRP and showed no significant change after PRP (p=0. 45).

These results suggested that PRP in diabetic patients was safe for retinal ganglion cells. Accompanying HTN and Duration of diabetes did not affect RNFL thickness. Another study with longer follow up period was needed to confirm the present study results. Acknowledgments: This project was supported by grant number 89778 of the Vice Chancellor for Research of the Mashhad University of Medical Sciences