Changes in the interpupillary distance with age and its effect on the near fusion free position

Usefulness Assessment of Automated Strabismus Angle Measurements Using Innovative Strabiscan Device

BACKGROUND

The variability of the obtained results of manual tests assessing the angle of strabismus depends on the experience, skills, and training of the examiner. The authors hope that this new measuring device will provide a more sensitive and repeatable method for detecting small strabismus angles compared to the gold standard-PCT. The purpose of this article is to present an innovative strabismus angle demonstration device, called Strabiscan, to provide automated measurements of eye deviation and to compare the obtained results of these measurements to the traditional manual method.

METHODS

For patients with manifest strabismic disease (n = 30) and a group of healthy subjects (n = 30), a detailed history was taken and routine ophthalmologic examinations were performed, including best-corrected distance visual acuity, assessment of refractive error using an autorefractometer after cycloplegia, biomicroscopic evaluation of the anterior segment of the eye and evaluation of the eye fundus by indirect ophthalmoscopy. Subsequently, each patient and healthy subject was subjected to a prismatic cover-uncover test using a manual method, after which the presence of strabismus was detected and its angle assessed using a Strabiscan demonstration device.

RESULTS

In the control group using the Strabiscan demonstration device, small-angle latent strabismus ≤ 3DP was diagnosed in 83% of patients, while >3DP was found in 13%. In contrast, using the prismatic cover-uncover test, latent strabismus ≤ 3DP was diagnosed in only 13% of patients, and latent strabismus with an angle > 3DP was found in 13% of patients. No statistically significant differences were noted in the measurements of strabismus angles made by the different methods.

CONCLUSIONS

The Strabiscan demonstration device allows quick and accurate assessment of the strabismus angle. Compared to the prismatic cover-uncover test, it has a higher sensitivity for detecting low-angle latent strabismus. Measurements with the Strabiscan do not require the presence of additional assistants for the test.

Locomotive Recalibration and Prism Adaptation of Children and Teens in Immersive Virtual Environments

As virtual reality expands in popularity, an increasingly diverse audience is gaining exposure to immersive virtual environments (IVEs). A significant body of research has demonstrated how perception and action work in such environments, but most of this work has been done studying adults. Less is known about how physical and cognitive development affect perception and action in IVEs, particularly as applied to preteen and teenage children. Accordingly, in the current study we assess how preteens (children aged 8-12 years) and teenagers (children aged 15-18 years) respond to mismatches between their motor behavior and the visual information presented by an IVE. Over two experiments, we evaluate how these individuals recalibrate their actions across functionally distinct systems of movement. The first experiment analyzed forward walking recalibration after exposure to an IVE with either increased or decreased visual flow. Visual flow during normal bipedal locomotion was manipulated to be either twice or half as fast as the physical gait. The second experiment leveraged a prism throwing adaptation paradigm to test the effect of recalibration on throwing movement. In the first experiment, our results show no differences across age groups, although subjects generally experienced a post-exposure effect of shortened distance estimation after experiencing visually faster flow and longer distance estimation after experiencing visually slower flow. In the second experiment, subjects generally showed the typical prism adaptation behavior of a throwing after-effect error. The error lasted longer for preteens than older children. Our results have implications for the design of virtual systems with children as a target audience.

Influence of age on measured anatomical and physiological interpupillary distance (far and near), and near heterophoria, in Arab males

PURPOSE

To compare the effects of age and near phoria on interpupillary distance measured at far (FIPD) and near (NIPD) using the Viktorin's and pupillometer (PD-5) methods.

METHODS

Interpupillary distance (IPD) by Viktorin's method and the corneal reflex pupillometer (PD-5) method, as well as near heterophoria by the Saladin near point card, were each obtained on 133 randomly selected normal subjects aged 20-67 years. Comparison within and between techniques, influence of age on IPD, and near heterophoria were assessed.

RESULTS

The mean FIPD varied significantly from the NIPD (P < 0.001 for both methods). Overall, FIPD ranged from 56-73 mm, and NIPD ranged from 50-70 mm. For FIPDs of 55 mm, 63 mm, and 71 mm, the corresponding NIPDs were less by 3.9 mm, 4.4 mm, and 5.0 mm, respectively, which were measured by Viktorin's method, and 4.0 mm, 4.6 mm, and 5.2 mm, respectively, measured by the PD-5 method. Between methods, the limits of agreement were: -3.9 mm and 3.2 mm (P > 0.05) for FIPD, and -3.1 mm and 2.9 mm (P > 0.05) for NIPD. Both IPDs varied significantly across age groups (P < 0.0001). Post hoc analysis revealed a significant variation (P < 0.01 in both techniques) only in the comparison between age groups 16-25 years and 41-67 years. The mean difference was -2.2 mm (-4.0 mm to -0.3 mm) and -2.8 mm (-4.7 mm to -1.0 mm) for Viktorin's method for FIPD and NIPD, respectively. For PD-5, the corresponding values were -1.3 mm (-3.2 mm to 0.4 mm) and -1.7 mm (-4.1 to -0.5 mm). Also, the near phoria differed significantly (P < 0.0001) across age groups and correlated positively with age (r(2) = 0.27, P < 0.0001) and NIPD (r(2) > 0.04; P < 0.03, both techniques).

CONCLUSION

The difference between FIPD and NIPD (about 4.4 mm in Arab males) was observed independent of the technique used. The Viktorin's and the PD-5 methods of IPD assessment resulted in similar values, and therefore, could be interchangeably used. However, caution is advised in cases of high power refractive corrections as the difference could vary from -4 mm to +3 mm (FIPD) and -3 mm to +3 mm (NIPD). Both IPDs have demonstrated an increase until the patients are in their early 40s, and a slight decrease has been observed thereafter. Age and NIPD were significantly associated with heterophoria in our subjects.

Craniofacial anthropometry in a Turkish population

OBJECTIVE

To present norms and demonstrate the anthropometric variations in fronto-occipital circumference, inner and outer canthal distances, near and distant [far] anatomical interpupillary distance, canthal index, and circumference-interorbital index across age and sex in urban Turkish subjects.

PARTICIPANTS

Three thousand four hundred forty-eight subjects (1852 male, 1596 female) aged 7 to 40 years were included in this study.

METHODS

Three age groups were studied: children aged 7 to 15 years, young adults aged 16 to 25 years, and adults aged 26 to 40 years. Mean values for each measured parameter were determined at each age between 7 and 25 years. Subjects were also divided into nine age subgroups to observe the change of each parameter with advancing age.

RESULTS

The fronto-occipital circumference and outer canthal distance of males was significantly (p <.001) wider than females in all age groups. The near and distant interpupillary distances of male subjects were, on average, wider than the female subjects with greater differences with advancing age. Across all subjects aged 7 to 40 years, the mean of all measured parameters and calculated indexes of men and boys was significantly different from girls and women (p <.001). The mean for interpupillary distances in our study in both sexes were found to be similar to Arabian, Hong Kong, and British children; larger than those of Chinese, Black, Indian, and Caucasians; and smaller than those of Mexican children and a mixed European population.

CONCLUSION

This study clearly shows the anthropometric variation for fronto-occipital circumference, inner canthal distance, outer canthal distance, near and distant interpupillary distance, canthal index, and circumference-interorbital index with age. These developmental data and the normal values of these measurements in healthy subjects are useful for dysmorphologists in the early identification of some craniofacial syndromes, hyper- and hypotelorism, and congenital or posttraumatic telecanthus and of planning surgical intervention. We suggest that the comparison of craniofacial dimensions of a patient must be performed with normal standards specific for age as well as sex and race.