Impact of accommodation, convergence and stereoacuity on perceived symptoms and surgical performance among surgeons

Association between stereoacuity and simulated clinical performance among dental students: an exploratory investigation

INTRODUCTION

Dentistry is a profession that requires a high level of the hand-eye coordination. Although considerable attention has been put on dental students' manual dexterity, little emphasis was made on students' visual competency as a variable influencing their competency. In this study, we aimed to assess the association between dental students' stereopsis and their pre-clinical performance.

METHODS

Dental students (n = 49) were required to perform the porcelain-fused-to-crown preparation for a lower first molar and an upper central incisor plastic teeth mounted on phantom heads. Performance was assessed by two faculty members based on two rubrics, which collectively included 11 assessment criteria. Afterward, students undertook a stereoacuity test using Randot stereotest. Stereopsis values greater than 40 arc/s were considered abnormal.

RESULTS

A significant negative correlation was seen between stereopsis scores and students' grades for the upper incisor (p < 0.01), but not for the lower molar. An association was also seen between abnormal stereopsis and students' poor performance in preparing the finish line of the incisor tooth (p = 0.024).

CONCLUSION

Abnormal stereopsis can impact dental students' performance, particularly when preparing teeth indirectly using a dental mirror. Dental educators should give attention to students' stereoacuity, in a manner similar to that given to students' manual dexterity.

A Digital Alternative to the TNO Stereo Test to Qualify Military Aircrew

INTRODUCTION: Stereopsis is usually required in military aviators and may become increasingly important with reliance on newer technologies such as binocular Helmet-Mounted Displays (HMDs) and stereo displays. The current stereo test used to qualify UK military aircrew (TNO test) has many limitations. To address these limitations, two computer-based digital versions of a random dot stereogram (RDS) were developed: a static version (dRDS-S), and a version in which the dots appear to move dynamically within the depth plane (dRDS-D), both capable of measuring stereo acuity to threshold.METHODS: There were 41 participants who performed all 3 stereo tests, TNO and both digital dRDS tests, on two separate occasions.RESULTS: The best (lowest) mean stereo acuity threshold was measured with dRDS-S (33.79 arcseconds, range 12.64-173) and the worst mean stereo acuity thresholds were measured with the TNO test (91 arcseconds, range 60-240). Both dRDS tests were strongly correlated, but neither correlated with the TNO test. Both dRDS tests were more reliable, as indicated with tighter limits of agreement.DISCUSSION: With a large floor effect at 60 arcseconds, the TNO test was unable to characterize any finer degree of stereo acuity. Both dRDS tests demonstrated better test-retest reliability and addressed many of the limitations seen with the TNO test. The dRDS tests were not correlated with the TNO test, which suggests that the TNO test does not provide the accuracy or reliability for use as a meaningful aeromedical screening test. The dRDS tests will enable research to investigate the relationship between stereo acuity and operational performance.Posselt BN, Seemiller E, Winterbottom M, Baber C, Hadley S. A digital alternative to the TNO stereo test to qualify military aircrew. Aerosp Med Hum Perform. 2022; 93(12):846-854.

Stereopsis and visual acuity: Bilateral trifocal versus blended extended depth of focus and diffractive bifocal intraocular lenses

PURPOSE

To compare stereopsis and visual acuity (VA) between bilateral implantation of trifocal intraocular lenses (IOL) and blended implantation of an extended depth of focus (EDOF) IOL with a bifocal IOL.

METHODS

This is a non-randomized, prospective comparative study included 74 eyes of 37 patients who underwent phacoemulsification and bilateral implantation of AT LISA tri 839MP IOL (bilateral group; 21 patients) or blended implantation of Tecnis Symfony ZXR00 and Tecnis ZLB00 IOL (blended group; 16 patients). The primary outcomes were stereoacuity and binocular VA. The secondary outcomes were visual defocus curve, quality of life, and patient satisfaction. Follow-up was performed 3 months after the surgery.

RESULTS

The mean near stereoacuity was 49.76 ± 22.67 and 120.63 ± 90.94 seconds of arc (arcsec) in the bilateral and blended groups, respectively (P < 0.001). Near stereoacuity was positively correlated with VA difference of two eyes (r = 0.896, P < 0.001). The mean binocular uncorrected visual acuity at 40 cm, 80 cm, 5 m, and corrected distance visual acuity at 5 m of the bilateral and blended groups was not statistically significant different. The bilateral group had better VA at a vergence from -2.5 to -4.0 D. Both groups obtained high quality of life and patient satisfaction scores.

CONCLUSION

The bilateral and blended groups achieved good binocular VA, quality of life, and high patient satisfaction. However, the near stereoacuity of the blended group was worse.

The relationship between visual impairments and activity of the neck/shoulder muscles among surgeons during simulated surgical tasks

BACKGROUND

Minimally Invasive Surgery (MIS) has an impact on surgeons' musculoskeletal and visual systems. However, the relationship between visual symptoms and musculoskeletal problems is not well understood.

AIM OF THE STUDY

This study used surface electromyography (sEMG) to examine changes in fatigue of the neck/shoulder muscles among surgeons with visual impairments when performing simulated surgical tasks in 2D and 3D viewing modes.

DESIGN

Cross-sectional laboratory study.

METHODS

Changes in median frequency (MDF, an indicator of muscle fatigue) were examined in 17 experienced gynaecologists. Four simulated surgical laparoscopy tasks were performed in 2D and 3D viewing modes. The MDF of three neck/shoulder muscles (cervical erector spinae, [CES], upper trapezii [UT], and anterior deltoids [AD]) were examined bilaterally. Visual parameters (accommodation, convergence, and stereoacuity) were measured prior to commencement.

RESULTS

There was a downward shift of MDF from simple to more complex tasks for the right and left CES and AD muscles but not the UT, which was consistent for surgeons with mild accommodation/convergence impairment and/or good stereoacuity. There were significant differences in the level of muscle fatigue of the neck/shoulder muscles according to the severity of visual impairment, muscle side, task and surgical performance level.

CONCLUSIONS

The results show a relationship between the degree of visual impairments and muscle fatigue of the neck/shoulder muscles among MIS surgeons. These findings have important implications in understanding the concurrence of musculoskeletal problems and visual symptoms.