Aim To investigate the changes in macular vessel density (mVD) and its relationship to macular ganglion cell–inner plexiform layer (mGCIPL) thickness in patients receiving ethambutol (EMB) therapy for tuberculosis without recognisable clinical symptoms or signs of EMB-induced optic neuropathy (EON).
Methods A total of 23 eyes of 13 patients using EMB therapy for 6 months without EON (preclinical EON) as the EMB group, 40 eyes of 23 healthy individuals as the normal control group and 18 eyes of 10 patients with tuberculosis before receiving EMB therapy as the blank control group were retrospectively analysed. The mean peripapillary retinal nerve fibre layer (pRNFL) and mGCIPL thicknesses and mVD were measured using optical coherence tomography angiography. Patients in the EMB group were compared with individuals in the normal and blank control groups, and changes in macular parameters were evaluated.
Results Central circle mVD (cCVD) was significantly lower in the EMB group than in both control groups (generalised estimating equation (GEE), p=0.003 and 0.029, respectively). The mGCIPL thickness in all regions and the mean pRNFL thickness were not significantly different between the EMB group and both control groups (GEE, p=1.000 for all). There were no significant differences in mVD, mGCIPL thickness and mean pRNFL thickness between the normal control and blank control groups (p>0.05). In the generalised linear model analyses, the minimum and inferonasal mGCIPL thicknesses were positively correlated with cCVD in the EMB group (β=1.285, p=0.003 and β=0.770, p=0.024, respectively).
Conclusions cCVD decreased with no changes in mGCIPL and mean pRNFL thicknesses in patients with preclinical EON. The minimum and inferonasal mGCIPL thicknesses were positively correlated with cCVD. cCVD might be an early indicator for monitoring early-stage EMB toxicity.
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Contributors Design: LS, WS,LZ, XS, ZB, SW, WG, QL, QX. Table/Data: LS, LZ, XS, WS, ZB, SW, WG, QL, QX. Writing – original draft: LS, QL,LZ, XS, WS, ZB, SW, WG, QX. Writing – review and editing: LS, SW,LZ, XS, WS, ZB, WG, QL, QX. Funding Acquired: LS.
Funding This article was supported by the Science and Technology Development Plan Project of Hangzhou (No. 20191203B129).
Competing interests None declared.
Patient consent for publication Written informed consent was obtained from the patient for publication of this research and any accompanying images.
Ethics approval Our study has obtained ethics approval. The ethics committee of Hangzhou Red Cross Hospital, 2018 (16); the informed consent form is placed in the supplemental file.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. The medical records of patients who were diagnosed with tuberculosis in our hospital between July 2019 and June 2020 were retrospectively reviewed.
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