Subthreshold Micropulse Laser Therapy (SML) in Retinitis Pigmentosa

Plain-language summary

Introduction Retinitis pigmentosa (RP) is the most common form of genetic retinal degenerative disease. The disease is progressive and leads to blindness and permanent disability within a few years of diagnosis. The etiology of RP is multifactorial. It combines genetic (multiple inheritance patterns) and environmental factors, which makes it difficult to develop effective causal therapy. Many potential methods of RP treatment have been described so far, but the lack of unequivocal evidence of the therapeutic effectiveness of these methods implies a lack of RP therapy standards. Few analyzes have shown that the use of a red subthreshold micropulse laser (SML) with a wavelength of 810 nm causes a neurostimulatory effect on the retina. The subsequent introduction of a yellow laser with a wavelength of 577 nm, dedicated to edema and ischemic retinal diseases, re-initiated a series of questions about the effectiveness of both therapies and the treatment protocols used. This fact emphasizes the need for further verification and optimization of SML treatment regimens in Poland, which has a chance to become a new, widely available, non-invasive standard of treatment independent of the genetic pattern. The aim of the project The main goal of the experiment is to verify the effectiveness of SML and determine the optimal treatment protocol for SML based on a detailed analysis of molecular changes of selected pro-inflammatory, neurotrophic and angiogenic factors (IL-1α, IL-1β, IL-2, IL-4, IL-5, IL- 6 IL-8, IL-10, IL-12 p70, IL-13, IL-17A, CXCL8 / IL-8, MCP-1 / CCL2, MIP-1α / CCL3, MIP-1β / CCL4, IL-8 / CXCL8, CCL5 / RANTES, IP-10 / CXCL10, GM-CSF, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-13, BMP-4, BMP-7, BMP - 9, TIMP-1, t-PA, PAI-1, NGF, EGF, TNF-α, TGF-β1, TGF-β2, FGF, EGF, G-CSF, GM-CSF, HGF, PDGF-AA, PDGF- AB / BB, VEGF, PAI-1, COL1A1, TSP-2, IFN-γ, N-cadherin, E-selection and P-selection) in tears and peripheral blood of patients with RP. Moreover, the project aims to personalize the assessed treatment regimens by determining the correlation between these changes and the genotype and dynamics of functional changes of the retina in the eyes from the RP subjected to single stimulation with yellow and red SML. Materials and methods The study group will consist of 60 adult patients with retinitis pigmentosa diagnosed on the basis of a characteristic clinical picture confirmed by genome analysis using the whole exome sequencing method and full-field electroretinoography (ERG). In randomized selection, one eye of each patient will be randomly assigned to be stimulated with red (30 eyes) or yellow (30 eyes) SML, and second eye will be assigned to the sham procedure. This will ensure a comprehensive comparative assessment of the effectiveness of both types of SML against each other and against a placebo. The tear film will be collected by wetting the Schirmer strips placed under the lower eyelid before SML (T0) and 28 days (T1), 3 months (T2) and 6 months (T3) after the laser stimulation. In addition, approximately 7.5 ml of peripheral venous blood will be collected at corresponding time points. The assessment of the dynamics of functional changes based on the measurements of the best corrected visual acuity for distance and near vision, contrast sensitivity, microperimetry, 10-2 and 30-2 static perimetry, electroretinogram stimulated with the pattern (PERG) and multifocal electroretinogram (mfERG) in both eyes will be carried out at the time points T0, T1-T3. In addition, during the T0-T3 visits, the morphology of the eyeball, i.e. examination of the anterior segment and fundus of the eye in a slit lamp, examination of optical coherence tomography of the macula and ultrasound of the eyeball will be assessed. The quality of life of the participants of the experiment will be assessed on the basis of the standardized NEI VFQ-25 questionnaire. The quality of life assessment will take place both before the implementation of the SML and during subsequent follow-up visits. Expected project benefits Conducting the proposed experiment will result in verification of the effectiveness of the retinal stimulation by the yellow SML in comparison to the red SML in the eyes with retinitis pigmentosa. In addition, conducting genome analysis and monitoring changes in the concentration of pro-inflammatory, neurotrophic and angiogenic factors in the tear film and peripheral blood in combination with a detailed assessment of the dynamics of functional changes in the eyes with RP after stimulation with an immunomodulatory stimulus SML will enable optimization and personalization of this treatment method in relation to the genetic profile of the patient with RP. The expected results may direct further research on the search for an effective therapy for patients with RP or constitute the basis for the introduction of the world's first standard of adjuvant treatment in this disease entity.

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