Aqueous humour concentrations of PEDF and Erythropoietin are not influenced by subthreshold micropulse laser treatment of diabetic macular edema

Alessandra Micera,Silvia Bini,Luisa Frizziero,Elisabetta Pilotto,Graziana Esposito,Edoardo Midena

doi:10.1042/bsr20190328

Abstract

Purpose: To determine if aqueous humour (AH) concentrations of Retinal Pigment Epithelium (RPE)’s biomarkers are modified after subthreshold micropulse laser (SMPL) treatment of diabetic macular edema (DME).Methods: Naïve DME and healthy subjects were enrolled. All DME patients received SMPL treatments (577-nm yellow light, 5% duty cycle of 0.2 s, power 250 mW), according to study protocol. AH of DME eyes was sampled at baseline and periodically after first SMPL treatment. Control eyes were sampled before cataract surgery. Pigment Epithelium Derived Factor (PEDF) and Erythropoietin (EPO) were quantified with glass-chip protein array.Results: Eighteen DME patients (central retinal thickness ≤ 400 μm on Spectral Domain Optical Coherence Tomography (SD-OCT)) and ten controls were enrolled. The main exclusion criteria were high refractive error, proliferative diabetic retinopathy, glaucoma and neurodegenerative disorders. PEDF concentration was decreased in DME patients at baseline versus controls (P=0.012), while EPO was increased (P=0.029). Both molecules’ concentrations remained stable during follow-up after treatments, compared with DME-baseline.Conclusions: The AH concentrations of RPE biomarkers were significantly different in DME treatment-naïve eyes versus controls. The expression of PEDF and EPO remained unchanged after treatments with SMPL in DME eyes. These data are relevant for future research and applications of SMPL.

Highlights

Laser photocoagulation has historically represented the major option for the treatment of diabetic macular edema (DME) [1]
We applied a proteomic approach on aqueous humour (AH) samples of DME patients in order to evaluate the effects of Subthreshold Micropulse Laser (SMPL) treatment on the concentration of retinal pigment epithelium (RPE) biomarkers after SMPL treatment
Even though the major contiguity of vitreous body to the retinal tissue would make vitreous samples hypothetically more reliable to analyse a retinal condition, the dynamics of ocular fluids allow a continuous exchange of solutes between the posterior and anterior compartments [15,16]

Summary

Introduction

Laser photocoagulation has historically represented the major option for the treatment of diabetic macular edema (DME) [1]. Subthreshold Micropulse Laser (SMPL) represents a new tissue-sparing technique [2,3,4] that prevents the formation of retinal scars, and allows anatomic and functional preservation [2]. Proteomic studies on ocular fluids, such as vitreous and aqueous humour (AH) samples, gained greater relevance to study the pathophysiology and the response to treatment of several ocular disorders [8,9,10]. The samples of AH, which is much more accessible than vitreous, has shown promising results in the proteomic approach, for anterior segment disorders – where contiguity of AH is high – and for the posterior pole diseases [8].

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