Validity and reliability of two Cirrus HD-OCT procedures for measuring objective ocular torsion.

PURPOSE: Torsional eye position by the disc-fovea angle (DFA) is a relevant objective parameter in vertical strabismus. DFA measurement with OCT has proven to be a good alternative to the gold standard measurement in fundus photography. Our study aims to analyze the validity and reliability of two undescribed Cirrus HD-OCT methods that offer clinical advantages for measuring objective cycloposition in normal patients compared to the Spectralis SD-OCT and the reference method. DESIGN: Prospective validity and reliability analysis. METHODS: Objective cycloposition by means of the DFA was measured in the right eyes of 59 binocularly normal individuals attending the ophthalmology service of a medical institution. DFA was obtained by fundus photography (gold standard), FoDi software of Spectralis SD-OCT, HD 1 Line scan of Cirrus HD-OCT and Macular Cube of Cirrus HD-OCT (Fundus, FoDi, Line and Cube methods, respectively). Measurements were performed three times for each method and the patient was repositioned and realigned between captures. For Fundus and Cube methods posterior manual quantification was made by two observers with external protractor software. RESULTS: The three OCT methods showed and excellent agreement with the fundus photography (ICC 0.83 to 0.84) with no significant differences comparing mean values (p = 0.36 for Fundus-FoDi, p = 0.09 for Fundus-Line, p = 0.09 for Fundus-Cube). Absolute differences between methods were 1.5 degrees. All methods showed an excellent reliability (ICC 0.92 for FoDi, 0.91 for Line, 0.92 for Cube, 0.91 for Fundus). Minimal detectable change was lower than 3 degrees and the absolute difference between repeated measurements was 1 degree for all methods. Interrater reliability was excellent for methods requiring manual quantification (ICC 0.98 for Cube, ICC 0.94 for Fundus). CONCLUSIONS: Measurement of the DFA by Cirrus HD-OCT methods in normal patients was a valid and reliable alternative for the cycloposition assessment. Among the methods, the Cirrus OCT HD 1 Line improved clinical performance due to the simplicity and speed of measurement, with no need to export the image for quantification.

Lower tear meniscus height measured by optical coherence tomography in children.

INTRODUCTION: While optical coherence tomography (OCT) measurements of the lower tear meniscus height (LTMH) have been reported in adults, here we obtained LTMH measurements through Fourier Domain OCT in healthy children and compared these with values obtained in healthy adults. METHODS: Participants were children 7-17 years of age and a control group of adults 20-40 years of age. Inclusion criteria were no abnormal eye conditions or the use of contact lenses. Candidates who fulfilled the TFOS DEWS II criteria for dry eye disease (DED) were excluded. All subjects underwent LTMH measurement (OCT Spectralis) and tests for non-invasive tear break-up time and ocular surface staining. Participants also completed the ocular surface disease index questionnaire. RESULTS: A total of 86 children and 27 adults were included. Mean LTMH values in the children and adult groups were 217.40 ± 71.40 µm and 225.0 ± 54.86 µm, respectively; p = 0.53. However, 59.3% of the children had an LTMH ≤210 µm suggestive of DED, compared with only 33.3% of adults (p = 0.02). For the children, no significant differences in LTMH were observed with sex or for those more or less than 12 years of age. CONCLUSIONS: Optical coherence tomography-derived LTMH measurements were obtained in healthy children. While values were similar in children and adults, a greater proportion of children had an LTMH compatible with a diagnosis of DED. More studies in different paediatric populations are required to establish a complete set of normative LTMH measurements.

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

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.

Validity and Reliability of Semiautomatic Ocular Cycloposition Measurement With Spectralis Optical Coherence Tomography.

PURPOSE: Disc-fovea angle determined by fundus photography (P-DFA) is considered the gold standard for cycloposition assessment. Fovea-to-disc alignment (FoDi) software of the spectral-domain optical coherence tomography (SD-OCT) (Spectralis) also measures the DFA (O-DFA) based on subject fixation and offers important clinical advantages. This study aimed to analyze the validity and reliability of measuring cycloposition using OCT and to determine its performance in eyes with poor foveal definition. DESIGN: Validity and reliability analysis. METHODS: In 60 eyes with normal foveal definition and 32 eyes with poorly defined fovea, ocular cycloposition was assessed by 2 observers using 5 fundus photographs and 5 FoDi analyses each. Patients were repositioned after every capture. RESULTS: Cycloposition assessed by O-DFA was 7.6 ± 3.5-degrees, and P-DFA was 7.9 ± 3.8-degrees. The concordance between methods was good (intraclass correlation coefficient [ICC], 0.71), with absolute differences ranging from zero to 4-degrees in 85% of the subjects. The precision was 1.4-degrees for O-DFA and 3.0-degrees for P-DFA. Repeatability and reproducibility were excellent in both techniques. In the group of patients with poor foveal definition, the precision of P-DFA changed from 3.0-degrees to 4.8-degrees, whereas the O-DFA remained stable. CONCLUSIONS: OCT had a good agreement with the fundus photography method. O-DFA showed better precision than P-DFA. O-DFA repeatability and reproducibility were excellent and unconditioned by foveal status.

Rotation of retinal vascular arcades and comparison with disc-fovea angle in the assessment of cycloposition.

BACKGROUND/AIMS: To assess the agreement between disc-fovea angle (DFA) and the retinal vascular arcades rotation to measure cycloposition. Device repeatability and reproducibility between observers were also evaluated. METHODS: Cycloplegic retinography was taken in 321 eyes of 165 normal patients and repeated in 18 eyes at least 24 h later. Two independent observers used software to determine DFA, vein-related angle (VRA) and artery-related angle (ARA) in every retinography. Mean value of related angle (MRA) (mean value of VRA and ARA) was calculated. RESULTS: Camera repeatability was good (Intra-class Correlation Coefficient, ICC 0.89). In Bland-Altman analysis, mean VRA, ARA and MRA were 4° to 5° different from DFA (p<0.01). There was poor correlation between DFA and other methods (ICC): DFA versus VRA 0.3, versus ARA 0.4, versus MRA 0.5. Reliability between observers was good in all methods. The multivariate analysis showed no interaction between each method and eye side, sex or observer (p>0.05). CONCLUSIONS: The rotation of retinal vascular arcades using a first-order approximation technique is no substitute to DFA when assessing torsion in fundus photographs. Of the methods tested, MRA correlated most closely, but DFA remains the gold standard for cycloposition. The rotation of vascular arcades provides a qualitative assessment, particularly in uncertain macular location.