ABSTRACT
PURPOSE: To describe a new stereotest in the form of a game on an autostereoscopic tablet computer designed to be suitable for use in the eye clinic and present data on its reliability and the distribution of stereo thresholds in adults. METHODS: Test stimuli were four dynamic random-dot stereograms, one of which contained a disparate target. Feedback was given after each trial presentation. A Bayesian adaptive staircase adjusted target disparity. Threshold was estimated from the mean of the posterior distribution after 20 responses. Viewing distance was monitored via a forehead sticker viewed by the tablet's front camera, and screen parallax was adjusted dynamically so as to achieve the desired retinal disparity. RESULTS: The tablet must be viewed at a distance of greater than â¼35 cm to produce a good depth percept. Log thresholds were roughly normally distributed with a mean of 1.75 log10 arcsec = 56 arcsec and SD of 0.34 log10 arcsec = a factor of 2.2. The standard deviation agrees with previous studies, but ASTEROID thresholds are approximately 1.5 times higher than a similar stereotest on stereoscopic 3D TV or on Randot Preschool stereotests. Pearson correlation between successive tests in same observer was 0.80. Bland-Altman 95% limits of reliability were ±0.64 log10 arcsec = a factor of 4.3, corresponding to an SD of 0.32 log10 arcsec on individual threshold estimates. This is similar to other stereotests and close to the statistical limit for 20 responses. CONCLUSIONS: ASTEROID is reliable, easy, and portable and thus well-suited for clinical stereoacuity measurements. TRANSLATIONAL RELEVANCE: New 3D digital technology means that research-quality psychophysical measurement of stereoacuity is now feasible in the clinic.
ABSTRACT
BACKGROUND: Treatment-induced increases in the height of the face may be permanent. AIMS: To determine if appliance-induced increases in the heights of the upper and lower molars in girls with Class II division 1 malocclusion, and the consequential increase in the height of the face are maintained. METHODS: Ten angles and 10 distances were measured on lateral cephalometric radiographs of 11 year-old girls (Range: 8.5-14.8 years) with treated (N = 9) and untreated (N = 8) Class II division 1 malocclusions. The intervals between the initial and recall records were, on average, 12 years (Range: 7.6-15.7 years) for the girls in the treatment group, and 8 years (Range: 4-13 years) for the girls in the untreated/control group. In the treatment group eight girls were treated with the Begg appliance and Class II elastics. RESULTS: Upper and lower molar dentoalveolar heights in both groups increased significantly between the initial and recall visits. There were no significant differences between the molar heights in the groups at the start or at recall. Anterior face height (AFH) also increased significantly in both groups between the initial and recall visits. At recall, AFH in the treatment group was significantly greater than AFH in the control group. This finding is attributed to a similar-sized difference between the groups at the start, to the longer period between the initial and recall records in the treatment group and to lesser variation in both groups at recall. In both groups, posterior face height increased significantly between the initial and recall stages. At the conclusion of the study there were no statistically significant differences between the treated and control groups in either overjet or the inclination of the upper incisors. Relapse of the upper incisors in the treatment group and retroclination of the upper incisors in the control group reduced the initial differences between the groups. These changes are attributed to altered lip posture and increased lip pressures in adolescence. At recall, angles SNA and SNB were significantly smaller in the treatment group. CONCLUSION: The heights of the upper and lower molars and the face increased in both groups. Orthodontic treatment may have no lasting effects on either the height of the face or the heights of the molars in girls with Class II division 1 malocclusion.
