Abstract
PurposeTranscorneal electrical stimulation (TES) is a novel treatment approach for patients with retinitis pigmentosa (RP). The aim of our study was to observe changes in optical coherence tomography angiography (OCTA) that would be attributed to TES treatment.MethodsA total of 73 eyes were included: 43 eyes of 22 subjects (11 ♀, 11 ♂) suffering from RP were examined at baseline (BL), after first stimulation (TS), 1 week (1W), and 6 months (6M) after treatment initiation and were compared with 30 control eyes of 15 subjects (8 ♀, 7 ♂). TES was performed simultaneously on both eyes for 30 min weekly. OCTA scans of 9 × 15 mm were recorded with a PLEX Elite 9000 swept-source OCTA device (Carl Zeiss Meditec AG, Jena). Vascular density metrics such as perfusion density (PD) and vessel density (VD) were calculated automatically for the macular area by using standardised extended early treatment diabetic retinopathy study (ETDRS) grids centred around the fovea. In addition, the capillary perfusion density (CPD) and the capillary flux index (CFI) of the peripapillary nerve fibre layer microvasculature in all four quadrants of an annulus centred at the optic disc were measured. All parameters were determined over all retinal layers and separately for the superficial (SCP) and deep capillary plexus (DCP). ANOVA-based linear mixed-effects models were calculated with SPSS®.ResultsThroughout the course of TES treatment, the macular VD and PD of all retinal layers in all subsections showed a slight decrement without reaching statistical significance, also when analysed separately in the SCP and DCP (p > 0.08). In analogy, the average CPD and CFI also presented with a slight decrement (p > 0.20). However, when compared with controls, most OCTA parameters showed a significant decrement (p < 0.05). When analysed systematically in all subsections of the extended ETDRS grid, the temporal macular subsections within the outer ring (radius 1.5–3 mm) and also of the peripheral C1, C2, and C3 rings (radius 3–7.5 mm) showed lower VD and PD values when compared with the other subsections (p < 0.05).ConclusionVascular density metrics in the macular region and the peripapillary microvasculature appear to remain unaffected by continuous TES treatment within a period of 6 months.
Highlights
Transcorneal electrical stimulation (TES) is a new treatment method for patients suffering from retinitis pigmentosa (RP) [1, 2]
73 eyes were enrolled in the study: 43 eyes of 22 patients diagnosed with RP (11 ♀, 11 ♂; 22 OS, 21 OD, 47.5 ± 15.2 years, range 20–81 years) and 30 age-matched control eyes from 15 healthy participants (8 ♀, 7 ♂; 15 OS, 15 OD, 43.8 ± 16.6 years, range 21–71 years)
The mean logMAR BCVA at BL was 0.23 ± 0.25 and improved slightly after 6 months of TES treatment (6M) to 0.22 ± 0.22, In general, the macular vessel density (VD) and perfusion density (PD) parameters in all retinal layers, when analysed separately in the SCP and deep capillary plexus (DCP), were significantly lower in almost all subsections when compared with controls (p < 0.05, Tables 1, 2, and 3)
Summary
Transcorneal electrical stimulation (TES) is a new treatment method for patients suffering from retinitis pigmentosa (RP) [1, 2]. In order to evaluate the therapeutic TES response in RP patients in a short-lasting, non-invasive, contact-free, and patient-friendly way, a recent study has shown that retinal vessel oximetry (RO) might be superior over full-field electroretinography (ffERG) or visual field (VF) as outcome measurement [1,2,3]. Since RO devices so far are mainly used in a scientific context and are mostly preserved to specialised ophthalmology centres, further monitoring methods that are short-lasting, non-invasive, contact-free, and patient-friendly and have a better availability in daily clinical practice are needed
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