ABSTRACT
Objective:To observe the effect of local retinal laser photocoagulation (local photocoagulation) on Coats disease.Methods:A 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.Results:Among 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. Conclusion:The 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.
ABSTRACT
Aim: To systematically refine and recommend parameter settings of spot size, power, and treatment duration using the Pascal® photocoagulator, a multi-spot, semi-automated, short-duration laser system. Materials and Methods: A retrospective consecutive series with 752 Caucasian eyes and 1242 laser procedures over two years were grouped into, (1) 374 macular focal / grid photocoagulation (FP), (2), 666 panretinal photocoagulation (PRP), and (3) 202 barrage photocoagulation (BP). Parameters for power, duration, spot number, and spot size were recorded for every group. Results: Power parameters for all groups showed a non-gaussian distribution; FP group, median 190 mW, range 100 – 950 mW, and PRP group, median 800 mW, range 100 – 2000 mW. On subgroup comparison, for similar spot size, as treatment duration decreased, the power required increased, albeit in a much lesser proportion than that given by energy = power × time. Most frequently used patterns were single spot (89% of cases) in FP, 5 × 5 box (72%) in PRP, and 2 × 2 box (78%) in BP. Spot diameters as high as ≈ 700 μm on retina were given in the PRP group. Single session PRP was attempted in six eyes with a median spot count of 3500. Conclusion: Overall, due to the small duration of its pulse, the Pascal® photocoagulator tends to use higher powers, although much lower cumulative energies, than those used in a conventional laser. The consequent lesser heat dissipation, especially lateral, can allow one to use relatively larger spot sizes and give more closely spaced burns, without incurring significant side effects.