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Paola Salvetti, Laura de Polo, Marta Oldani, Rosita Ruello; Early changes on SD-OCT in eyes with cystoid macular edema (CME) after 577 nm subthreshold MicroPulse Laser Treatment (MPLT). Invest. Ophthalmol. Vis. Sci. 2013;54(15):4141.
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© ARVO (1962-2015); The Authors (2016-present)
To describe early changes on SD-OCT at 15 days after 577 nm subthreshold micropulse laser treatment (MPLT) in eyes with cystoid macular edema (CME)
10 eyes of 10 patients with CME (9 diabetic retinopathy and 1 BRVO) were reviewed 15 days after high density grid subthreshold treatment over the edematous area identified on OCT using HRA Spectralis MultiColor (Heidelberg Engeneering). Grid treatment was performed by the same operator (PS) using the Iridex IQ 577 yellow laser delivered through an Area Centralis lens (Volk). MicroPulse treatment parameters were: 100 µm spot size, 100 ms duration, 5% duty cycle, using 2x the power determined in a test burn performed with the same spot, same duration, but in continuous wave (CW) emission over a non edematous area starting at 60 mW and titrating the power up until a barely visible burn was noted. Multicolor images (IR, Blue reflectance and Green reflectance), fundus autofluorescence (FAF) images, as well as OCT volume centered on fovea were obtained before treatment. OCT images obtained 15 days after treatment using the repeat scan software were reviewed independently by two different operators (PS & LdP). Interoperator agreement was calculated using Cohen’s K (0.8). For each patient 3 scans (superior, central and inferior respective to fovea) within the OCT volume were reviewed, before and after treatment. Retinal thickness, morphology and number of exudates, morphology and number of cysts were noted, as well of retinal pigment epithelium (RPE) status on scans
On all the reviewed OCT scans, retinal thickness remained stable in 83% and was reduced in 17% at 15 days. Morphology of cyst and exudates appeared changed (cyst in 60% and exudates in 63%). Cysts had disappeared in 27% and exudates in 7% of scans. RPE appeared intact in all scans (100%) with no discernable sign of laser impact. No differences were noted on either the color images or FAF images between before and after treatment.
Subthreshold MPLT appears to have a morphologic effect as early as 15 days after treatment. This would rule out the possibility of changes due to diabetes control. 100 ms subthreshold MPLT emission duration appears to be sufficient to produce a biological response leading to anatomical changes, therefore challenging the accepted boundaries of how much treatment is needed to be effective.
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