Author: Randa Falah
Co-authors: Alejandro Filloy Rius, Olivia Pujol Carreras, Anna Boixadera Espax, Miguel angel Zapata Victori, Josep Garcia Arumi
Abstract
Purpose: to report a case of subthreshold micropulse yellow laser (577 nm) treatment for macular edema due to type 1 idiopathic macular telangiectasia (IMT) that was nonresponsive to laser photocoagulation nor to intravitreal injections, with a 12 months follow-up period.Setting/Venue: A collaboration between the Retina Departments of the Vall d'Hebron Hospital in Barcelona, Spain and the University Hospital of Tarragona Joan XXIII in Tarragona, Spain.
Methods: A 51-year-old male, diagnosed with type1 idiopathic macular telangiectasias in his left eye (LE) in 2016 and in follow-up at our department since then. At the time of the diagnosis, he had come to our center due to decreased vision in his LE that persisted for 2 months.
On initial examination, his best-corrected visual acuity (BCVA) was 20/20 in the right eye and 20/40 in the LE. Fundus examination of the LE showed juxtafoveal capillary telangiectasia and circinate hard exudates in the macula. Spectral domain optical coherence tomography showed severe cystoid macular edema (CME). He was first treated with antiangiogenic intravitreal injections that was then combined with laser photocoagulation. However, both treatments were ineffective and BCVA in the LE was 20/63 at that time. We tried treatment with several Dexametasone intravitreal implants, and although a partial reduction of the CME was achieved, it was transitory due to recurrence. Furthermore, our patient developed ocular hypertension with difficult management, and a cataract that was removed by phacoemulsification surgery.
Since no other treatment options were described, we administered 577 nm subthreshold micropulse yellow laser (STYL) around the juxtafoveal telangiectatic area. We preformed a total of 2 treatment sessions of STYL, 6 months apart.
Results: In the first STYL session, 700 spots were performed with the following settings: 160-μm spot diameter, 20-ms duration, 5% duty cycle and power of 250 mW.
At two months follow-up, circinate hard exudates were diminished, a complete CME resolution was observed and BCVA in the left eye was 20/40.
6 months after SMYL, some intraretinal cysts reappeared but with no circinate exudates and with a stable BCVA. We performed the second SMLY treatment with 570 spots and power of 250mW in area of vascular malformations detected by ocular coherence tomography angiography, 800 microns temporal to fovea.
One month after the last treatment, Spectral domain optical coherence tomography showed improvement of CME with some remanent intraretinal cyst and there was no definite retinal damage on fundus autofluorescence.
For 1 year after the first SMYL, the patient’s left eye remained stable, and best-corrected visual acuity improved to 20/32.
Conclusions: Subthreshold micropulse laser treatment is a type of nondamaging retinal laser therapy that raises the temperature of the retinal pigment epithelium to just below the threshold for protein denaturation, thereby preventing retinal damage. It has been intensively used for selected retinal diseases in the last decade.
Our case report shows that SMYL may be effective in the CME of type 1 IMT, especially in cases that do not respond to other available treatments.
In the literature, there are other similar case reports where subthreshold micropulse laser was used in type 1 IMT resistant to intravitreal injections or as a combined therapy. However, no case series are available due to the uncommon nature of the disease. Therefore, we believe that subthreshold micropulse laser could offer an additional treatment option in those cases of idiopathic macular telangiectasia type 1 unresponsive to other known treatments.