Short Pulse Laser Induces Less Inflammatory Cytokines in the Murine Retina after Laser Photocoagulation

Abstract

Aims: The purpose of this study was to evaluate the effect of pulse duration on the expression of inflammatory cytokines in the murine retina after laser photocoagulation treatment with a PASCAL® pattern scan laser photocoagulator and conventional laser treatment. Methods: Retinal scatter laser photocoagulation was performed on C57BL/6J mice using a short pulse (10 ms) with a PASCAL laser or conventional settings (100 ms) with a multicolor laser. Eyes were enucleated before treatment (control) and 1 day, 3 days and 7 days after treatment. The levels of inflammatory cytokines (i.e., VEGF, MCP-1, RANTES and IL-6) in the retina/choroid were quantified by an ELISA. The expression patterns of VEGF and macrophages (i.e., F4/80) in the retina/choroid were evaluated by immunohistochemistry. Results: The levels of RANTES, IL-6 and MCP-1 after PASCAL and conventional laser treatments were significantly elevated compared with controls (p < 0.05). Conventional laser treatment, but not PASCAL treatment, resulted in the up-regulation of VEGF. RANTES and IL-6 levels on day 1 and MCP-1 levels on day 3 in the sensory retina were also significantly up-regulated with conventional laser treatment compared with PASCAL treatment (p < 0.05). Immunohistochemical analysis showed that PASCAL treatment was associated with lower VEGF and F4/80 expression levels compared with conventional laser treatment. Conclusions: Our data suggested that the short pulse duration induced fewer inflammatory cytokines in the sensory retina compared with the conventional pulse duration. Short pulse laser photocoagulation with the PASCAL may prevent macular edema after panretinal photocoagulation.

Panretinal Photocoagulation Using Short-Pulse Laser Induces Less Inflammation and Macular Thickening in Patients with Diabetic Retinopathy

“…Some reports indicate that the elevated levels of cytokines and inflammatory reactions may be involved in the pathogenesis of the macular edema after PRP [4–7]. Apart from our study group, other investigators have also showed that thermal burns from laser photocoagulation induce the upregulation of vascular endothelial growth factor (VEGF) and several proinflammatory cytokines in mice and rabbits [7, 8].…”

“…Apart from our study group, other investigators have also showed that thermal burns from laser photocoagulation induce the upregulation of vascular endothelial growth factor (VEGF) and several proinflammatory cytokines in mice and rabbits [7, 8]. In addition, it has been reported that the vitreous humor levels of cytokines, including VEGF, interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and monocyte chemotactic protein-1 (MCP-1), are related to retinal permeability and to DME severity [9].…”

“…This shorter pulse duration results in the destruction within the retina and choroid and is less painful and offers better preservation of retinal sensitivity for the patient than the conventional laser [11–14]. Ito et al showed that short-pulse laser (SPL) induced fewer inflammatory cytokines than the conventional-pulse-duration laser in the retina of mice [7]. However, the SPL requires a greater number of spots to complete PRP than conventional laser because the expansion of laser scars of SPL is less [12, 15].…”

Laser Photocoagulation in Retinal Vein Occlusion

“…In addition conventional laser treatment, but not PASCAL treatment, resulted in the up-regulation of VEGF. In Ito et al [27] study immunohistochemical analysis showed that PASCAL treatment was associated with lower VEGF and F4/80 expression levels compared with conventional laser treatment. They also suggested that the short pulse duration with the PASCAL induced fewer inflammatory cytokines in the sensory retina compared with the conventional pulse duration which may prevent macular edema after panretinal photocoagulation.…”

“…They reported that this biological change indicates pan-retinal laser therapy cause diffuse, intense but reversible retinal inflammation. According to Ito et al [27] study after both Pattern scan laser (PASCAL) and conventional laser treatments, some inflammatuar mediators level such as RANTES (regulated upon activation in normal T cells, expressed secreted) IL-6 ( interleukin-6) and MCP-1 (monocyte chemoattractant protein-1), were significantly elevated compared with perfusion; and (3) hemi-CRVO with involvement of only one half of the retina surface and this type is also divided into ischemic and nonischemic types like CRVO. The both CRVO and hemi-CRVOs have thrombosis at the level of the lamina cribrosa.…”