Minimal detectable change of the disc‐fovea angle for ocular torsion assessment

Abstract

Purpose The disc‐fovea angle (DFA) is used as a relevant indicator of ocular torsion change in cyclovertical strabismus. However, interpretation of the variation in time must differentiate whether a real change has occurred or if the disparity is due to random measurement error. The aim of the study was to obtain the minimal detectable change (MDC) of the DFA. It represents the minimal variation between two measurements that may be considered a real ocular torsion change. Methods A prospective cross‐sectional study was conducted in San Carlos Clinical Hospital of Madrid, Spain. Sixty healthy right eyes from 60 patients (31 men and 29 women) were recruited. Three digital fundus photographs were obtained, and between measurements, the patient moved their head away from the head support and then returned. Two observers quantified the DFA with software designed with MATLAB. Test‐retest and interrater reliability were calculated. Results Mean participant age was 56.1 years (SD 16.6, range 25–85). Mean DFA was 8.1° (SD 3.5, range 1.3–18.5). Test‐retest reliability for Observer 1 (Ob1), Observer 2 (Ob2) and interrater reliability were excellent (ICC 0.80, 0.83 and 0.95, respectively). Precision was 2.9° (Ob1) and 3.0° (Ob2), and the MDC95 was 4.1° (Ob1) and 4.2° (Ob2). Bland‐Altman analysis revealed an absence of bias and a homoscedastic distribution of the differences. Conclusions The MDC of the DFA in fundus photography was 4°, which represents the minimal change that may be considered a real change in ocular torsion. This result may improve the interpretation of ocular torsion changes in surgery and clinical scenarios.

Total intracranial hemorrhage volume measurement summating all compartments best in traumatic and nontraumatic intracranial bleeding

“…Definitions of excellent hemostatic efficacy of such treatments should be higher than the MDC of the measurement to be accurately detected. Although MDC has been used in multiple medical disciplines before (Dontje et al., 2018 ; Gavrielides et al., 2013 ; Katajapuu et al., 2020 ; Oda et al., 2010 ; Oxnard et al., 2011 ; Piedrahita‐Alonso et al., 2021 ), to our knowledge, this study is the first to establish ICrH volume MDC among readers.…”

“…Although MDC has been used in multiple medical disciplines before (Dontje et al, 2018;Gavrielides et al, 2013;Katajapuu et al, 2020;Oda et al, 2010;Oxnard et al, 2011;Piedrahita-Alonso et al, 2021), to our knowledge, this study is the first to establish ICrH volume MDC among readers.…”

Automated measurement of the disc-fovea angle based on DeepLabv3+

“…Piedrahita et al The DFA was calculated by manually acquiring the optic disc edge and macular center. The mean absolute difference between the repeated measurements was 1.64° ( 10 ).These semi-automatic methods still need to be operated by ophthalmologist and they are poor repeatability, low accuracy, and time-consuming. The automatic DFA measurement utilized in this study can directly obtain DFA values after inputting fundus images, thus making it more efficient and accurate.…”

“…Currently, DFA measurement based on fundus images are mainly measured manually and suffer from an average error of 2.0 (±1.8) ( 9 ). There were several disadvantages in manual measurement of DFA: poor reproducibility, low accuracy and time-consuming manual measurement ( 6 , 10 ). Therefore, it is necessary to research automatic DFA measurement methods.…”

“…Simiera et al proposed the Cyclocheck software, which measured DFA by locating the center of the macula and its tangent line to the optic disc ( 6 ). Piedrahita et al ( 10 ) designed a DFA measurement software by using MATLAB language and the software needed manually locate the optic disc edge and macular center to calculate the DFA. The above methods were suitable for single-image measurement and required physician participation; its disadvantages include the requirement of step-by-step completion, poor repeatability, and low efficiency.…”