OCT measures of lateral and medial recti
Reviewed by Fiona Rowe

The authors assessed the agreement of the measurements of the horizontal rectus muscle insertion distance to the limbus and the muscle thickness between three different OCT devices. This was a cross section observation study of 70 eyes of 35 subjects. A subgroup of 20 eyes of 20 subjects was extracted to consider intra- and inter- observer and intra-instrument reproducibility. Mean subject age was 31.7±8.7 years and 63% were female. Mean axial length was 24.5±1.2mm. The lateral and medial recti muscles were measured in all subjects. Lateral rectus muscle thickness was measured at 8.5mm in all cases with Triton, in 95.7% with Spectralis and in 94.3% with Cirrus. Thickness was measured at 10.5mm in 78.6% with Triton, 75.7% with Spectralis and in 74.2% with Cirrus. Mean lateral rectus muscle distance to limbus was 6.5±0.43mm with Triton, 6.51±0.47 with Spectralis and 6.46±0.47 with Cirrus. Mean medial rectus muscle distance to limbus was 5.11±0.3mm with Triton, 5.2±0.44 with Spectralis and 5.13±0.44 with Cirrus. There were no significant differences for these measurements. Mean lateral rectus thickness at 8.5mm was 202.6±39.4mm, 199±42.6 and 203.3±50.6 with Triton, Spectralis and Cirrus respectively. Mean lateral rectus thickness at 10.5mm was 195.6±41.5mm, 187.1±44.6 and 198.1±49.4 with Triton, Spectralis and Cirrus respectively. Mean medial rectus thickness at 7.2mm was 167.7±33.5mm, 170.7±44.9 and 163.9±30.1 with Triton, Spectralis and Cirrus respectively. Mean medial rectus thickness at 9.2mm was 205.2±52.7mm, 222.1±57.8 and 225.6±47.3 with Triton, Spectralis and Cirrus respectively. There were no significant differences for these measurements. Reproducibility measures were high for agreement. The results suggest that OCT is an effective and reproducible technique for measuring insertion distance to limbus and thickness of horizontal rectus muscles. Highest agreement for insertion distance was between the Spectralis and Triton devices and also for thickness. Higher agreement was found for lateral rectus versus medial rectus measurements.

Agreement between three optical coherence tomography devices to assess the insertion distance and thickness of horizontal rectus muscles.
De-Pablo-Gomez-de-Liano L, Fernandez-Vigo JI, Ventura-Abren N, et al.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2017;54(3):168-76.