ObjectiveTo observe the effect of local retinal laser photocoagulation (local photocoagulation) on Coats disease.MethodsA retrospective clinical study. From January 1, 2006 to August 1, 2020, 48 patients (48 eyes) who were diagnosed as Coats disease and received focal photocoagulation at The Eye Hospital Affiliated to Wenzhou Medical University were included in the study. Among them, there were 40 males (40 eyes) and 8 females (8 eyes). The average age was 32.46±22.41 years old. Nine eyes were in stage 2A, and 39 eyes were in stage 2B. All affected eyes underwent best corrected visual acuity (BCVA), color fundus photography and fluorescein fundus angiography (FFA).The BCVA was carried out using a standard logarithmic visual acuity chart, which was converted into the logarithmic minimum angle of resolution (logMAR) visual acuity during statistics. According to age, patients were divided into the adolescent group (age≤ 20 years old) and the adult group (age＞21 years old), with 18 eyes in 18 cases and 30 eyes in 30 cases, respectively. In the adolescent group, 18 eyes of 18 cases were all male; the average age was 11.17±3.31 years; the average logMAR BCVA was 0.83±0.60. Among the 30 patients in the adult group, 22 patients were male and 8 patients were female. the average age was 49.26±15.26 years old; the average logMAR BCVA was 0.82±0.59. All the affected eyes were treated with focal photocoagulation. Laser parameters were as followed: wavelength 577 nm, spot diameter 500 μm, exposure time 0.5 to 0.7 s, spot intensity level Ⅲ. FFA was FFA was performed 3 to 4 months after the first laser photocoagulation, and laser treatment was repeated as needed. The average follow-up after first treatment was 36.88±36.92 months. The changes in BCVA, abnormal blood vessels in the fundus, and hard exudation were observed.ResultsAmong 48 eyes, 36 eyes (75.00%, 36/48) received multiple local photocoagulation treatments. At the last follow-up, 36 eyes (75.00%, 36/48) had an improved or stable vision, and 17 eyes (35.42%, 17/48) had BCVA ≤ 0.32 logMAR units (≥ 0.5). The average logMAR BCVA of eyes in the adolescent group was 0.66±0.54, which was higher than the baseline, but the difference was not statistically significant (Z=－1.126, P=0.260). The average logMAR BCVA of the eyes in the adult group was 0.96±0.79, which was lower than the baseline, but the difference was not statistically significant (Z=－0.482, P=0.630). Among 48 eyes, abnormal blood vessels were completely or partially occluded in 42 eyes (87.50%, 42/48); of which, 29 eyes were completely occluded (60.42%, 29/48), and 13 eyes were partially occluded (27.08%, 13/48)). The hard exudation at macula or peripheral retina were completely absorbed or obviously absorbed in 40 eyes (83.33%, 40/48); among them, the complete and obvious absorption were 11 (22.92%, 11/48) and 29 (60.42%, 29/48) eyes.ConclusionThe treatment of focal photocoagulation with a larger spot, long exposure and weak level Ⅲ spot can effectively seal abnormal blood vessels in the eyes of Coats disease,reduce hard exudation and improve or stabilize vision.