Construction and application of an object-oriented computer model for simulating ocular positioning defects

Design, Implementation, and Observer-based Output Control of a Super-coiled Polymer-Driven Two Degree-of-Freedom Robotic Eye

The prevalence of ineffective corrective surgeries for ocular motor disorders calls for a robotic eye platform in aiding ophthalmologists to better understand the biomechanisms of human eye movement. This letter presents the first hardware design and implementation of a 2-DOF robotic eye driven by super-coiled polymer (SCP) artificial muscles. While our previous work designed and simulated a deep deterministic policy gradient (DDPG) learning-based controller that requires full-state feedback of the SCP-driven robotic eye, measuring the temperature states of the slender SCPs is generally impractical for the ubiquitously aimed robot. To address this predicament, this letter proposes a reduced-order state observer to estimate the temperature of SCPs given the kinematic measurements. Combining the designed observer and the learning-based controller, the closed-loop output feedback control is implemented on the robotic eye prototype to examine its performance on three classical types of eye movements: visual fixation, saccadic pursuit, and smooth pursuit. The experimental results are presented which successfully validate the observer-based output control of the SCP-driven robotic eye.

Computer-based simulation of the Bielschowsky head-tilt test using the SEE++ software system

INTRODUCTION

Latest measurements of the vestibulo-ocular reflex (VOR) allowed the integration of the simulation of the Bielschowsky head-tilt test (BHTT) into the SEE++ software system. SEE++ realizes a biomechanical model of the human eye in order to simulate eye motility disorders and strabismus surgeries. With the addition of the BHTT it can now also be used for differential-diagnostic simulations of complex disorders (e.g., superior oblique palsies).

METHODS

In order to simulate the BHTT in SEE++, the user can freely choose the desired head-tilt angle from -45 degrees to +45 degrees. The chosen angle is shown in the 3D view with a human body model and is also used in the calculation of the Hess-Lancaster test.

RESULTS

The integration of the BHTT offers an additional improvement of the possibilities for simulating eye motility disorders. Moreover, SEE++ allows the creation of a video of the "virtual patient" while tilting the head from one side to the other, which shows dynamic changes in the simulated Hess-diagrams.

DISCUSSION

Comparisons of simulation results with patient-measured data showed a good correlation between the simulated and the measured data. Further comparisons with patient data are planned.

Using 3D computer simulations to enhance ophthalmic training

PURPOSE

To develop more effective methods of demonstrating and teaching complex topics in ophthalmology with the use of computer aided three-dimensional (3D) animation and interactive multimedia technologies.

METHODS

We created 3D animations and interactive computer programmes demonstrating the neuroophthalmological nature of the oculomotor system, including the anatomy, physiology and pathophysiology of the extra-ocular eye muscles and the oculomotor cranial nerves, as well as pupillary symptoms of neurological diseases. At the University of Vienna we compared their teaching effectiveness to conventional teaching methods in a comparative study involving 100 medical students, a multiple choice exam and a survey.

RESULTS

The comparative study showed that our students achieved significantly better test results (80%) than the control group (63%) (diff. = 17 +/- 5%, p = 0.004). The survey showed a positive reaction to the software and a strong preference to have more subjects and techniques demonstrated in this fashion.

CONCLUSION

Three-dimensional computer animation technology can significantly increase the quality and efficiency of the education and demonstration of complex topics in ophthalmology.