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Giulia Midena, Stela Vujosevic, Ferdinando Martini, Enrica Convento, Elisabetta Pilotto, matteo federici, VALERIA PAGLIEI, ANGELO MARIA MINNELLA, Edoardo Midena; Retinal layers and microperimetry changes after subthreshold micropulse laser in the treatment of diabetic macular edema. Invest. Ophthalmol. Vis. Sci. 2017;58(8):947.
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© ARVO (1962-2015); The Authors (2016-present)
To report on individual retinal layer changes after treatment of diabetic macular edema (DME) with subthreshold micropulse laser (SML), and correlate with functional changes over one year.
Ten patients with previously untreated DME and suitable for SML as first line treatment (central retinal thickness >300μm, but < 450μm) underwent a complete ophthalmologic evaluation including: BCVA determination, slit-lamp biomicroscopy, Spectral Domain OCT and microperimetry at baseline, 3, 6, 9, 12 months. Seven fellow eyes with subclinical/no DME served as controls. Treatment was performed using a yellow laser (IQ 577, Iridex, USA) in SML modality (100 μm spot, 0.2 sec, 5% duty cycle, energy 250 mW). The thickness of 7 retinal layers was calculated, by Spectral Domain OCT. All retinal OCT layer thickness was performed twice, by two independent masked graders. Re-tretament was allowed after 3 months if edema was persisting.
At baseline, mean central retinal thickness (CRT) was 360±37.4µm in DME eyes (treated group), and 304.4±19.8µm in no/subclinical DME eyes (untreated), (p=0.021); Inner nuclear layer (INL) central thickness was 43.6±17.2µm in DME and 29.3±7.9µm in untreated eyes, (p= 0.044); Henle’s fiber + outer nuclear layer central thickness (Henle’s+ONL) was 141.5±31.1µm in DME, and 106±11.3µm in untreated eyes, (p=0.044). Improvement of following parameters was found in treated versus untreated eyes at 9 months: INL thickness in the inner temporal sector (-0.2±2.3µm vs 1.7±1.8µm;p=0.05); at 12 months: mean CRT (-23±39.6µm vs +17.9±20.6µm, p=0.032); INL thickness in the temporal inner sector (-0.7±4.2µm vs +2±2.2µm, p=0.041); BCVA (+5.6±9.1 vs -0.7±3 letters, p=0.0239). No changes in the thickness and integrity of outer retinal layers were found in any eye during the entire follow-up. BCVA and retinal sensitivity were inversely correlated with: Henle’s+ONL thickness (p<0.0001), and only BCVA to INL thickness (p<0.0001).
INL and Henle’s plus ONL are sites of increased retinal thickness in eyes with DME, when analysed by retinal layers segmentation. Subthreshold micropulse laser treatment improves both morphologic and functional parameters of DME treated eyes. Retinal sensitivity is mainly correlated to Henle’s plus ONL thickness. The exact mechanism of reduction in thickness of INL, induced by SML, remains to be further investigated.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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