If the Waveform Score provides information on the reliability of the signals, a score <3.50 may indicate an unreliable signal, and the signal should be discarded. We also recommend taking three measurements with all the signals having a Waveform Score of 3.50 or above to increase the precision.

Purpose:The aim of this study was to determine the repeatability of high-and lowcontrast visual acuity (VA) measurements at near. Methods: Fifty-five normal subjects were recruited. Inclusion criteria included visual acuity of at least 0.00 logarithm of minimum angle of resolution (logMAR) on each eye at distance. One eye was selected for this study, either the one with a better acuity or randomly chosen if there was no difference between the two eyes. Near VA was measured in a random order with the PolyU high-contrast (PolyU-HC), the PolyU low-contrast (PolyU-LC), the Precision high-contrast (P-HC) and the Precision low-contrast (P-LC) charts at 400 mm. Measurements were repeated after one to two weeks. Repeatability was presented using the 95% limits of agreement between visits. Results: The between-visit repeatability was Ϯ0.063 logMAR for high-contrast and Ϯ0.141 for low-contrast using the PolyU charts. The between-visit repeatability was Ϯ0.120 logMAR for high-contrast and Ϯ0.110 for low-contrast using the Precision charts. Seventeen subjects had high-contrast VA better than -0.10 logMAR using Precision chart, which could not be measured by PolyU chart. The mean difference between high-and low-contrast VA was 0.108 from the Precision charts (median difference of 0.10 or one line). Conclusions:The Precision charts could measure high-contrast near VA to threshold level. Practitioners should be aware of a VA difference of more than one line in repetitive measurement, at both high and low contrast. A difference in near high-and low-contrast VA of more than one line may warrant further investigation.

Background:The aim was to compare the anterior segment of two groups of Chinese using the Pentacam system. Methods: Fifty young (median age 21 years) and 50 middle-aged (median age 46 years) subjects with equal numbers of males and females had their axial length measured with the IOL Master. Their axial anterior chamber depth, anterior chamber volume and temporal and nasal anterior chamber angles were measured using the Pentacam and comparisons were made between the two groups. Results: Both groups shared similar axial lengths (unpaired t-test: p = 0.37) but young subjects had significantly deeper anterior chamber by 11 per cent (3.60 Ϯ 0.40 mm) compared with middle-aged subjects (3.24 Ϯ 0.34 mm) (analysis of variance: p < 0.001). The anterior chamber volume was significantly greater in young subjects by 24 per cent (200.12 Ϯ 35.59 mm

This study demonstrated the feasibility of DCT over silicone hydrogel lenses. Low lens modulus silicone hydrogel contact lens in situ has no clinical effect on DCT.

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