Reproducibility of morphoscopic contrast sensitivity testing with the Visual Capacity Analyzer

Evaluation of the precision of contrast sensitivity function assessment on a tablet device

The contrast sensitivity function (CSF) relates the visibility of a spatial pattern to both its size and contrast, and is therefore a more comprehensive assessment of visual function than acuity, which only determines the smallest resolvable pattern size. Because of the additional dimension of contrast, estimating the CSF can be more time-consuming. Here, we compare two methods for rapid assessment of the CSF that were implemented on a tablet device. For a single-trial assessment, we asked 63 myopes and 38 emmetropes to tap the peak of a “sweep grating” on the tablet’s touch screen. For a more precise assessment, subjects performed 50 trials of the quick CSF method in a 10-AFC letter recognition task. Tests were performed with and without optical correction, and in monocular and binocular conditions; one condition was measured twice to assess repeatability. Results show that both methods are highly correlated; using both common and novel measures for test-retest repeatability, however, the quick CSF delivers more precision with testing times of under three minutes. Further analyses show how a population prior can improve convergence rate of the quick CSF, and how the multi-dimensional output of the quick CSF can provide greater precision than scalar outcome measures.

Purified high-dose anthocyanoside oligomer administration improves nocturnal vision and clinical symptoms in myopia subjects

The aim of the present study was to determine the effect of purified high-dose anthocyanoside oligomer administration on nocturnal visual function and clinical symptoms in low-to-moderate myopia subjects. The study was a randomized, double-blind, placebo-controlled trial and involved sixty subjects with asthenopia and refractive errors between −1·00 and −8·00 diopters in both eyes. Thirty subjects were administered a purified high-dose anthocyanoside oligomer (100 mg tablet comprising 85 % anthocyanoside oligomer), and thirty were given a placebo in tablet form twice daily for 4 weeks. Prior to the treatment, the placebo and anthocyanoside groups were similar in terms of age and contrast sensitivity. Before and after treatment, subjects completed a questionnaire to determine their clinical symptoms and were also assessed for nocturnal visual function using contrast sensitivity testing. Questionnaire data analysis showed that, following treatment, twenty-two (73·3 %) anthocyanoside subjects showed improved symptoms, whereas only one placebo subject showed an improvement (Fisher's exact test,P<0·0001). Contrast sensitivity levels according to each cycle per degree significantly improved in the anthocyanoside group and remained stable in the placebo group. The mean contrast sensitivity change in the anthocyanoside group was 2·41 (SD) 1·91, compared with −0·66 (SD) 2·66 dB for the placebo group (unpaired Student'sttest,P<0·0001). At all cycle per degree levels, contrast sensitivity changes in the anthocyanoside group were better than in the placebo group (unpaired Student'sttest,P<0·05). The present data show that the administration of anthocyanoside oligomer appears to improve subjective symptoms and objective contrast sensitivity in myopia subjects with asthenopia.

Visual quality after wavefront-guided LASIK for myopia

This study evaluated the visual quality after wavefront-guided laser in situ keratomileusis (LASIK) for treating myopia. Thirty-two eyes with moderate myopia (-5.78 - -2.17D) and 25 eyes with high myopia (-7.78 - -6.17D) were prospectively reviewed. The contrast sensitivity (CS), glare and the total higher order aberrations (HOA) were measured before and 1 week, 1 month and 2 months after LASIK. The pupil diameter was measured at day- and night-time illumination. The CS and glare at all spatial frequencies were not reduced after wavefront-guided LASIK (p<0.05) and the difference between the moderate and high myopia group was not significant. No significant correlation was found between the amounts of myopia and the postoperative CS (p>0.05). The area under the log contrast sensitivity function (AULCSF) showed no correlation with the total HOA (r2=-0.071, p=0.612, between the daytime AULCSF and the total HOA with a 4 mm entrance pupil, r2=-0.176, p=0.260, between the nighttime AULCSF and the total HOA with a 6 mm entrance pupil). There was no decrease in CS and glare after wavefront-guided LASIK for myopia. In conclusion, wavefront-guided LASIK based on the individual ablation patterns is a good option for refractive surgery to improve the visual quality in both moderate and high myopia cases.