Test-retest repeatability and agreement of the quantitative contrast sensitivity function test: towards the validation of a new clinical endpoint.

PURPOSE: The purpose of this study is to investigate test-retest reliability and agreement of the quantitative contrast sensitivity function test (qCSF) in the retina clinic. METHODS: A total of 121 right eyes of 121 patients were tested and consecutively re-tested with qCSF in the retina clinic. Outcomes included area under the logarithm of contrast sensitivity function curve (AULCSF), contrast acuity, and contrast sensitivity thresholds at 1-18 cycles per degree (cpd). Test-retest means were compared with paired t-test, variability was compared with the Brown-Forsythe test, and intraclass correlation coefficient (ICC) and Bland Altman plots evaluated reliability and agreement. RESULTS: Mean test-retest differences for all qCSF metrics ranged from 0.02 to 0.05 log units without statistically significant differences in variability. Standard deviations ranged from 0.08 to 0.14. Coefficients of repeatability ranged from 0.16 to 0.27 log units. ICC > 0.9 for all metrics except 1cpd (ICC = 0.84, all p < 0.001); AULCSF ICC = 0.971. CONCLUSION: qCSF-measured contrast sensitivity shows great test-retest repeatability and agreement in the retina clinic.

Structure-function associations between contrast sensitivity and widefield swept-source optical coherence tomography angiography in diabetic macular edema.

PURPOSE: To evaluate the relationship between contrast sensitivity (CS) and widefield swept-source optical coherence tomography angiography (WF SS-OCTA) vascular metrics in diabetic macular edema (DME) was the purpose. METHODS: This prospectively enrolled cross-sectional observational study included 61 eyes of 48 patients that were tested with the quantitative CS function (qCSF) test on the same day as imaging with WF SS-OCTA (PLEX® Elite 9000, Carl Zeiss Meditec) 3 × 3, 6 × 6, and 12 × 12 mm scans. Outcomes included visual acuity (VA) and multiple qCSF metrics. Vascular metrics included vessel density (VD) and vessel skeletonized density (VSD) in the superficial (SCP) and deep capillary plexus (DCP) and whole retina (WR) and foveal avascular zone (FAZ) parameters. Mixed effects multivariable linear regression models controlling for age, lens status, and diabetic retinopathy stage were performed. Standardized beta coefficients were calculated by refitting the standardized data. RESULTS: SS-OCTA metrics had a significant association with CS and VA. The effect size of OCTA metrics was larger on CS compared to VA. For example, the standardized beta coefficients for VSD and CS at 3 cpd (ßSCP = 0.76, ßDCP = 0.71, ßWR = 0.72, p < 0.001) were larger than those for VA (ßSCP = - 0.55, p < 0.001; ßDCP = - 0.43, p = 0.004; ßWR = - 0.50, p < 0.001). On 6 × 6 mm images, AULCSF, CS at 3 cpd, and CS at 6 cpd were significantly associated with VD and VSD in all three slab types (SCP, DCP, and WR), while VA was not. CONCLUSION: Structure-function associations in patients with DME leveraging the qCSF device suggest microvascular changes on WF SS-OCTA are associated with larger changes in contrast sensitivity than VA.

Quantitative contrast sensitivity test to assess visual function in central serous chorioretinopathy.

BACKGROUND: To characterise the contrast sensitivity function (CSF) in central serous chorioretinopathy (CSCR) compared with healthy controls using novel computerised contrast sensitivity (CS) testing with active learning algorithms. METHODS: Prospective observational study measuring CSF in CSCR eyes and controls using the Manifold Platform (Adaptive Sensory Technology, San Diego, California). Mixed effects multivariate regression models were used. Outcomes included area under the log CSF (AULCSF), CS thresholds at 1, 1.5, 3, 12 and 18 cycles per degree (cpd) and best-corrected visual acuity (BCVA). Associations of contrast outcomes with structural findings on optical coherence tomography (OCT) and subjective symptomatology were investigated. RESULTS: Forty CSCR eyes and 89 controls were included with median BCVA logarithm of median angle of resolution 0.10 (20/25) versus 0.00 (20/20), respectively (p=0.01). When accounting for age, CSCR was associated with significantly reduced median AULCSF (p=0.02, ß=-0.14) and reduced CS thresholds at 6 cpd (p=0.009, ß=-0.18), 12 cpd (p<0.001, ß=-0.23) and 18 cpd (p=0.04, ß=-0.09), versus controls. Within the CSCR group, subjectively perceived visual impairment (N=22) was associated with significantly decreased CS thresholds at all spatial frequencies and in AULCSF compared with asymptomatic CSCR eyes (N=18). Ellipsoid zone attenuation and subfoveal fluid on OCT were associated with decreased AULCSF and CS thresholds specifically at 3, 6 and 12 cpd, whereas presence of extrafoveal fluid at 1.5 and 3 cpd. CONCLUSION: Contrast sensitivity is significantly reduced in CSCR, and strongly correlates with subjective visual impairment. Different structural biomarkers correlate with contrast thresholds reductions at different spatial frequencies.