Effect Of 577nm Subthreshold Micropulse Laser On Macular Morphology And Microcirculation In Chronic Central Serous Chorioretinopathy

Objective Optical Coherence Tomography Angiography(OCTA)was used to detect the changes of macular morphology and microcirculation in eyes with chronic central serous chorioretinopathy(cCSC)before and after 577nm subthreshold micropulse laser(SML)treatment,in order to evaluate the efficacy and safety of SML in the treatment of cCSC,and to further explore its the possible mechanism.Methods This study collected 19 patients(19 eyes)with cCSC diagnosed in the Ophthalmology department of Subei People’s Hospital from August 2020 to December 2022,and the leakage point was within 500μm of the macular fovea.All eyes were treated with 577nm subthreshold micropulse laser,The laser parameters are set as follows:the spot size is 200μm,the exposure time is0.02s,the duty cycle is 5%,and the constant pulse energy of 400mw is used to cover the neuroepithelial detachment area of the fovea.All eyes were examined by routine ophthalmology,optical coherence tomography(OCT)and OCTA before treatment and 2 weeks,1 month,3 months and 6 months after treatment,collecte the best corrected visual acuity(BCVA),central macular thickness(CMT),subfoveal choroidal thickness(SFCT),foveal subretinal fluid thickness(SRF),blood flow density index of 6mm×6mm in macular area,including macular superficial capillary plexus vessel density(SCPVD),deep capillary plexus vessel density(DCPVD),choriocapillaris vessel density(CCVD),foveal non-vascular area(FAZ)area,perimeter,and vessel density around the FAZ-300,blood flow density within 300um around the FAZ area(FD-300)at each time point.To compare the changes of macular morphology and microcirculation of cCSC at each time point before and after SML treatment.Blood flow density and structural parameters before and after treatment were compared by repeated single factor analysis of variance or nonparametric test(Friedman test).Results1.At 2 weeks,1 month,3 months and 6 months after SML treatment the Log MAR BCVA of cCSC eyes were(0.41±0.43),(0.41±0.42),(0.38±0.42),(0.37±0.45),which were gradually increased than those before treatment(0.49±0.51),but there was no significant difference among the groups(χ~2=8.480,P=0.075).2.At 3 months and 6 months after SML treatment the CMT of cCSC eyes were decreased significantly than those before treatment(P=0.008,P=0.003).The results of pairwise comparison showed that there were significant differences between 3 months,6 months after treatment and 2 weeks after treatment(P=0.043,P=0.016).3.At 1 month,3 months and 6 months after SML treatment the SRF of cCSC eyes were 109.00(77.00,240.00)μm,75.00(0.00,134.00)μm and 32.00(0.00,89.00)μm,which were decreased significantly than those before treat ment 173.00(119.00,285.00)μm(P=0.018,P=0.001,P=0.001),there was no significant differrence between 2 weeks after treatment and before treatment(P>0.05).4.At 1 month,3 months and 6 months after SML treatment the SFCT of cCSC eyes were decreased gradually than that before treatment,and the difference was statistically significant only at 3 months and 6 months after treatment(P=0.017,P=0.001).5.At 2 weeks,1 month,3 months and 6 months after SML treatment the CCVD of cCSC eyes were increased than that before treatment,only the difference was statistically significant at 3 months and 6 months after treatment(P=0.009,P=0.037).However,there was no significant difference in SCPVD,DCPVD,FAZ area,perimeter and FD-300 at 2 weeks,1 month,3months and 6 months after treatment(P>0.05).Conclusion1.During the period of 6 months after 577nm subthreshold micropulse laser treatment,although the BCVA of cCSC eyes were gradually increased,to compare that before treatment there was no significant difference.2.At 1 month after 577nm subthreshold micropulse laser treatment,the foveal subretinal fluid of cCSC eyes was significantly absorbed and at 3month after 577nm subthreshold micropulse laser treatment,the CMT was decreased significantly.3.At 3 months after 577nm subthreshold micropulse laser treatment,the SFCT was decreased significantly and choroidal capillary blood flow density increased significantly in cCSC eyes.4.577nm subthreshold micropulse laser has no significant effect on cCSC eyes retinal blood flow density in a short period of time.