Detection and monitoring of subclinical ocular siderosis using multifocal electroretinogram

• Published in: Eye (London) Vol. 33; no. 10; pp. 1547 - 1555
• Main Authors: Sahay, Pranita, Kumawat, Devesh, Gupta, Shikha, Tripathy, Koushik, Vohra, Rajpal, Chandra, Mahesh, Venkatesh, Pradeep
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2019; Nature Publishing Group
• Subjects: 692/699/3161/3175; 692/699/578; Acuity; Adolescent; Adult; Case-Control Studies; Electroretinography; Eye; Eye Foreign Bodies - diagnosis; Eye Foreign Bodies - physiopathology; Eye Foreign Bodies - surgery; Female; Hemosiderosis - diagnosis; Hemosiderosis - physiopathology; Hemosiderosis - surgery; Humans; Iron; Laboratory Medicine; Male; Medicine; Medicine & Public Health; Middle Aged; Monitoring, Physiologic; Ophthalmology; Pharmaceutical Sciences/Technology; Prospective Studies; Retina; Retina - physiopathology; Retinal Diseases - diagnosis; Retinal Diseases - physiopathology; Retinal Diseases - surgery; Siderosis; Surgery; Surgical Oncology; Trauma; Vitrectomy; Young Adult
• ISSN: 0950-222X; 1476-5454
• DOI: 10.1038/s41433-019-0442-y

Background Although full-field electroretinogram (ffERG) is the gold standard test to detect physiological dysfunction in siderosis, it measures overall retinal function. This study aims to determine if multifocal electroretinogram (mfERG) can detect subclinical siderosis in eyes with an iron intraocular foreign body (IOFB). Methods Twenty eyes of 20 patients with retained iron IOFB, clear ocular media and good visual acuity (≥20/120) were enroled in this prospective case-control study. The fellow eyes served as control. These were evaluated with ffERG and mfERG at baseline. Serial mfERG was done till six months after pars plana vitrectomy with IOFB removal. Primary outcomes measures were amplitude and peak time of P1 and N1 wave of mfERG. Results The median age was 25 years (range 18–55). Most patients ( n  = 14/20) presented within a month of trauma. Baseline ffERG showed no difference in either ‘a’ or ‘b’ wave amplitude or peak time between cases and controls. However, on mfERG, there was a significant decrease in P1 and N1 wave amplitude and delay in P1 wave peak time in <2° retinal ring in cases as compared to controls ( p  = 0.001, 0.001 and 0.02 respectively) despite variability in results. At 6 months, P1 amplitude showed significant improvement from baseline in cases ( p  = 0.010). However, P1 peak time did not show significant recovery ( p  = 0.65). Conclusions mfERG may reveal subclinical electrophysiological retinal dysfunction in eyes with iron IOFB in cases with normal ffERG. P1 peak time may serve as an electrophysiological marker for past retinal damage.