Author: Beatriz Torrellas (Spain)
Co-authors: Beatriz Torrellas Darvas, Alejandro Filloy Rius, Abul Barkat Mustafa
To analyze the effectiveness and safety of 577 nm yellow subthreshold laser (STL) in the treatment of Chronic Central Serous Chorioretinopathy (CCSC) delivered in a fovea-sparing pattern as well as the changes in choroidal structure visible on Swept-Source Optical Coherence Tomography (SS-OCT).
The study was conducted at the Joan XXIII University Hospital in Tarragona from 2018 to the present time as a prospective, interventional, non-randomized, case series.
Diagnosis of CCSC was based on clinical examination, SS-OCT, Fundus Autofluorescence (AF) and Fluorescein Angiography (FA). Patients enrolled received treatment with 577nm subthreshold yellow laser titrated at 1/3 of minimum power to deliver minimally visible burn using 160µm spots at 5% duty cycle. Spots were delivered in a confluent pattern guided through OCT, AF or FA avoiding the fovea and 200µm area around it. Results were recorded at 6-12 weeks and from there on a basis determined by every individual’s evolution as well as the decision to administer further treatment. We registered Best Visual Acuity (BCVA, Snellen charts), SS-OCT and AF. Every case was analyzed for changes in BCVA, subretinal fluid (SRF) and Choroidal Thickness (CT) as well as visible laser changes on OCT or AF. Patients with a history of use of steroid treatment in the previous 6 months and other evolving ocular conditions were excluded. The same experienced surgeon performed STL treatment in all cases. The study was conducted in accordance with the Declaration of Helsinki. Statistical analysis was performed using StataCorp2020. Student's t test was used to determine the significance of the differences in mean values. A P value of 0.05 or lower was considered statistically significant.
The study included 37 eyes of 34 patients diagnosed with CSC. All patients received STL treatment as described. Mean age was 54.3 ± 10.7 years old (range 37-77). Patients were mostly men (76.6%). After STL, BCVA improved in 72.7% of patients and remained stable in 27.3%. BCVA did not decrease after STL in any patient. Mean CT before STL was 364.2 ± 82.6µm (range 271 to 406). At 12 weeks follow-up, it was 280 ± 114.5µm (range 199 to 361, p<0.05). During this same period, Choriocapillaris and Sattler layer (C-S) thickness changed from 57.7 ± 22.6µm (range 34 to 150) to 34 ± 1.4µm (range 17 to 122, p<0.05). While Haller layer thickness changed from 306.5 ± 68.7µm (range 214 to 340) to 246 ± 115.9µm (range 164 to 328, p<0.05). The ratio between Haller and C-S layer thickness was 5.7 before treatment. It increased to 7.3 (p<0.05) at week 12. Overall, there was a reduction of 23.1% in total CT (40.9% in C-S layer and 19.7% in Haller layer). There were no changes at the level of retina or RPE observed in fundus photography, SS-OCT or AF that could be accounted as laser-related complications.
STL has yielded positive results in terms of effectiveness and safety for the treatment of CCSC, which do not seem to be diminished by the use of a fovea sparing technique, this may be of interest for novice laser practitioners. The changes observed in CT after treatment have consisted in a significant thinning both at the level of Choriocapillaris and Sattler layer and Haller layer, being proportionally higher in the former. This thinning might be related to a laser-induced change in the choroidal circulation.
We have no financial relations to declare.