Influence of Retinal Microsecond Pulse Laser Treatment in Central Serous Chorioretinopathy: A Short-Term Optical Coherence Tomography Angiography Study

Abstract

Background: Central serous chorioretinopathy (CSC) is a common macular condition characterized by detachment of the neuroretina and is a frequent cause of central vision loss in adults. Among the various therapeutic strategies, subthreshold microsecond pulsed laser (SML) treatment has become a useful option. Despite the suggested involvement of choroidal circulatory disturbances in CSC, the effects of this treatment on macular microperfusion have not been fully evaluated yet. Herein, we report the impact of SML on retinal and choroidal microvascular flow using non-invasive optical coherence tomography (OCT) angiography (OCTA). Methods: In this study, CSC patients with persistent subretinal fluid (SRF) with or without secondary choroidal neovascularization (CNV) were included (referred to as the pachychoroid neovasculopathy (PNV) group and the CSC group, respectively). SML was conducted using a yellow (577 nm) laser with a duty cycle of 10%, spot size of 200 µm and duration of 200 ms. Best corrected visual acuity (BCVA) as well as OCT and OCTA images were evaluated at baseline and 4 weeks after SML. OCTA parameters of interest included full retinal perfusion (FRP), choriocapillaris perfusion (CCP), Sattler’s layer perfusion (SLP), and Haller’s layer perfusion (HLP), which were evaluated longitudinally and compared to unaffected fellow eyes. Results: 27 affected eyes and 17 fellow eyes from 27 patients were included. Before treatment, central retinal thickness (CRT) and subfoveal choroidal thickness (SFCT) of affected eyes were significantly larger than in fellow eyes. Four weeks after SML, CRT decreased significantly, whereas perfusion parameters did not change. In subgroup analyses, the CSC group showed a significant decrease in SFCT, whereas the PNV group did not despite the decrease in CRT. Conclusion: Our results suggest that the SML may affect the SFCT of the CSC, but not the PNV patients at least within four weeks following treatment. This effect seems to be independent of the change in choroidal perfusion measured with OCTA.

OCT biomarkers related to subthreshold micropulse laser treatment effect in central serous chorioretinopathy

“…Decreased SFCT was noticed after different treatments for CSCR [ 28 – 31 ]. Similar alterations of choroid thickness after SML treatment were also reported by other researchers [ 21 , 22 ]. Compared with observation, choroidal thickness was significantly lower in the SML-treated group at eight weeks, sixteen weeks, and six months after treatment in acute CSCR [ 15 ].…”

“…Arsan et al demonstrated SML could significantly increase BCVA and decrease SRF in non-resolving CSCR patients [ 21 ]. Prasuhn et al showed decreased central retinal thickness after SML in CSCR patients with persistent SRF either with or without secondary CNV [ 22 ]. However, compared with half-dose PDT, SML has a lower SRF complete resolution rate [ 23 ].…”

Temperature Increase and Damage Extent at Retinal Pigment Epithelium Compared between Continuous Wave and Micropulse Laser Application

“…As described above, sublethal RPE hyperthermia has already been clinically proven to be effective in the treatment of several macular diseases such as CSC [5][6][7][8] and DME [9][10][11][12], and this applies to both MP [6,8,11] and CW [32]. Basic experiments have shown an increase in heat shock proteins [34] and subsequent various protective and anti-oxidative stress responses [35], the secretion of cytokines from RPE cells that may lead to improved retinal function [36] and the reduction of the thickness of Bruch's membrane, suggesting inducing elimination of locally accumulated lipids [37].…”

“…The micropulse system applies repetitive microsecond pulses (MP) with breaks in between and claims to provide a milder temperature increase at and around the retinal pigment epithelium (RPE) than CW irradiation [4]. In fact, the MP mode has been shown to be effective in the treatment of different macular diseases such as central serous chorioretinopathy (CSC) [5][6][7][8] and diabetic macular edema (DME) [9][10][11][12]. However, a universal understanding of the correct mechanisms of action has not been achieved yet and controversial discussions continue.…”

Selective retina therapy and thermal stimulation of the retina: different regenerative properties - implications for AMD therapy

“…These laser therapies induce a sublethal temperature increase in RPE cells, leaving neuroretina intact. SDM, SML and NRT have shown a beneficial effect on a variety of diseases, such as macular edema in diabetic retinopathy [ 30 ] and central serous chorioretinopathy [ 29 ]. Dosing of power remains an unsolved safety issue, especially since the intended region of treatment is the macula.…”