Comparative study between single session pattern short pulse laser and conventional pan-retinal photocoagulation regarding efficacy and macular thickening in patients with diabetic retinopathy

Aim: The aim of this study is to compare the effect of pan-retinal photocoagulation (PRP) using short-pulse laser (SPL) performed in a single session and conventional laser, regardless of the number of spots, in terms of their effect on the progression of diabetic macular edema (DME) and efficacy of regression of signs in patients with proliferative and high-risk nonproliferative diabetic retinopathy (NPDR). Methods: A prospective comparative case series was carried out, in which eyes with a similar degree of severe nonPDR or high-risk PDR underwent four-session PRP using a conventional laser in one eye (Group a) and a single session SPL in the other eye (Group b). After the session, colored photographs were taken to show immediate laser reaction. A follow-up visit was scheduled at 6 weeks to detect any complication. Finally, fluorescein angiography and optical coherence tomography were repeated at 3 months to assess the efficacy of laser treatment and the remeasure the macular thickness. Best-corrected visual acuity (BCVA) was remeasured after 12 weeks and compared to the prelaser VA. Results: The 20 patients included had a mean age of 53.4 ± 6.4 years. All patients had hemoglobin A1c (HBA1c) ranging from 7.2 to 8.4 with a mean of 7.7 ± 0.5. Before PRP initiation, there was no statistically significant difference between the two groups as regards mean age, duration of DM, and mean HBA1c. The mean power of laser was 198.7 ± 13.26 mW and 393.2 ± 17.7 mW (P < 0 0001), the total energy delivered was 49.7 ± 11.4 mJ and 12.1 ± 5.3 mJ (P < 0 0001), and the number of spots were 1784.2 ± 89.7 and 2773.2 ± 159.2 (P < 0 0001) in the Conventional (Conv) group and SPL group, respectively. At the final follow-up visit at 12 weeks, there was no statistically significant difference regarding the mean central macular thickness (P = 0.84) and BCVA (P = 1.0). One eye from each group was diagnosed with persistent diabetic retinopathy activity at 12 weeks, for which intravitreal ranibizumab was given twice, 1 month apart. The FA was repeated 3 months later with the disappearance of signs of activity. Conclusion: The current study revealed that SPL in a single session is as effective as conventional laser-performed in the same patient with a similar degree of DR in both eyes-to cause regression of diabetic retinopathy signs without causing progression of DME. This was achieved with a total number of laser shots approximately 1.5 times the number in the conventional laser-treated eyes.