·Investigation·
A
novel three-dimensional electric ophthalmotrope for improving the teaching of
ocular movements
Lei Xiong1, Xiao-Yan Ding2, Ya-Zhi
Fan1, Yao Xing1, Xiao-Hui Zhang1, Ting Li1,
Jian-Ming Wang1, Feng Wang1
1Department of Ophthalmology, the
Second Affiliated Hospital, Xi’an Jiaotong University, Xi’an 710004, Shaanxi
Province, China
2Department of Ophthalmology, Xi’an
No. 3 Hospital, Xi’an 710082, Shaanxi Province, China
Correspondence to: Jian-Ming Wang and Feng Wang. The
Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710004, Shannxi
Province, China. xjtuwjm@163.com; wfoculist@126.com
Received:
Abstract
AIM: To develop a novel three-dimensional (3D) electric ophthalmotrope to improve
the ophthalmology teaching effectiveness and evaluate the teaching value.
METHODS: A 3D electric ophthalmotrope was designed by
simulating the movement of the ocular and the extraocular muscles according to
Sherrington’s law. The model with joint bearing was to ensure the flexibility
and centripetal rotation of the simulated ball and stepper motor as the driving
device. A programmable processor was used to control the motion amplitude of
the stepper motor. The size of hole was set at the back of the simulated shell
to limit the amount of eye movement. Afterwards, using a 5-point Likert scale,
7 experts evaluated the 3D electric ophthalmotrope’s simulation ability and
precision, compared with the traditional anatomical model. In addition, the
teaching effectiveness of the 3D electric ophthalmotrope was evaluated at
in-class quiz and final exam in a randomized controlled trial.
RESULTS: The 3D electric ophthalmotrope could be operated
easily to demonstrate the eye movements with motion of different ocular
muscles. The experts agreed that the 3D electric ophthalmotrope was different
from the traditional model and was easier for students to understand every
extraocular muscles’ movement in each evaluation index (P<0.05).
Moreover, the results of teaching effectiveness showed that the 3D electric
ophthalmotrope were significantly greater than the traditional model both at
in-class quiz (P<0.01) and final exam (P<0.05).
CONCLUSION: This novel 3D electric ophthalmotrope is better than
the traditional model, which can be to improve the ophthalmology teaching
effectiveness for students to understand the extraocular muscles’ movement.
KEYWORDS: extraocular muscles movement; ocular
myopathy; medical education; ophthalmotrope; three-dimensional electric model
DOI:10.18240/ijo.2019.12.12
Citation: Xiong
L, Ding XY, Fan YZ, Xing Y, Zhang XH, Li T, Wang JM, Wang F. A novel
three-dimensional electric ophthalmotrope for improving the teaching of ocular
movements. Int J Ophthalmol 2019;12(12):1893-1897
INTRODUCTION
The extraocular musculature is
always a difficult topic for students to learn in ophthalmology classes because
the interlaced distribution of six extraocular muscles forms the complicated
anatomical structure. The function of the six extraocular muscles is very
complex[1]. The medial rectus muscle and the
lateral rectus muscle are simply inward and outward, but the other four muscles
distribute in three dimensions and form a three-dimensional (3D) composite motion.
Surprisingly, their movements are sometimes synergic and sometimes mutually
antagonistic[2].
At present,
anatomy diagrams and anatomy models are usually used for ophthalmology
teaching. The anatomy diagrams are two-dimensional and do not give a good
representation of the stereo structure. With the development of science and
technology, 3D technology has been developed rapidly[3].
There are a lot of clinical discipline used vivid 3D model in medical education,
such as anatomy, osteology, otolaryngology and surgery department[4-7]. However, the eye models are
static, which only show the structure in orbit without movement[8]. It is still difficult for students to understand the
ocular myopathy during ophthalmology teaching using the traditional static
model for interpreting physiological movement of extraocular muscles[9]. There is no vivid 3D anatomical model available for
teaching the extraocular muscles movements[10].
In the present study, we developed a novel electric ophthalmotrope that could
simulate the movement of the extraocular muscles dynamically, and evaluate the
teaching effectiveness of the novel model compared with that of traditional
instruction with anatomical atlases.
MATERIALS AND METHODS
Ethical
Approval The study protocol has been approved
by the Ethics Committee on human research of the Second Affiliated Hospital of
Xi’an Jiaotong University. This research adhered to the tenets set forth in the
Declaration of Helsinki, and written informed consent was provided by all
students.
Instrument
Design The electric ophthalmotrope designed
between March 2014 and September 2015 using joint bearing to ensure the
flexibility and centripetal rotation of the simulated eyeball. Stepper motors
were used as the driving device to simulate muscle motion (Figure 1). A
programmable processor is used to control the motion amplitude of the stepper
motor. In addition, the size of hole was set at the back of the simulated shell
to limit the amount of eyeball movement (Figure 2). The design of different
parts is described below.
Figure 1
External and internal views of the shell and circuit diagram A: Spherical shell containing a
plastic hollow sphere and supportive structure; B: Internal structure including
a joint bearing, four aligning axes, horizontal bar and a triangular support
seat; C: Planar graph of internal structure view; D: Circuit diagram of
electrical control system.
Figure 2
Design drawing of 3D electric ophthalmotrope A: The lateral view with exterior frame;
B: Lateral view without the frame, showing that an elastic band starts from
above the spherical shell through the “U” shaped metal ring witch simulated
tackle, and further extends to the left rear. A lead hammer is used to maintain
its extension. C: An integrated circuits box and power supply are located on
the bottom of the sphere model; D: The location of the three-motion device.
3D Electric
Ophthalmotrope’s Inner Structure A 12-cm diameter plastic hollow
sphere representing the ocular surface was shown in color pigments (Figure
3D Electric
Ophthalmotrope’s Supporting Structure
A joint
bearing located in the center of the sphere of the eye model constitutes a
concave spherical connection similar to the human joint that allows free
rotation of two interconnected parts (Figure 1B,
3D Electric
Ophthalmotrope’s Movement Controls Outside the sphere of the eye model,
we used elastic bands to represent the extraocular muscles. So, we used three
elastic bands to represent the six extraocular muscles, in order to demonstrate
the principle of pairwise conjugate of extraocular muscles. The positions of
simulated extraocular muscles connected to the three motors as shown in Figure
2. Motor No.1 (motion device 1) is responsible for abduction and adduction, and
Motor No.2 (motion device 2) elevates and depresses. Motor No. 3 (motion device
3) is located at left front of the model, and its direction is same as the
direction of the inferior oblique, simulating movement of the inferior oblique
muscle by driving elastic band No.3.
Furthermore,
an indicating elastic band is used to show the trend of the superior oblique
muscle. This indicates that elastic band starts from above the spherical shell,
goes through the “U” shaped metal ring of the simulated tackle (Figure 2B),
which is located at the upper left of the PMMA box, and further extends in the
left rear direction. A lead hammer (Figure 2B) weighing
Experts’
Evaluation of the 3D Electric Ophthalmotrope Seven professors were invited to
evaluate our model. Two professors came from the Department of Anatomy at Xi’an
Jiaotong University, others from the Ophthalmology Department, the Second
Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China. All experts
were requested to fill out two questionnaires. The first is to evaluate 3D
electric ophthalmotrope’s simulation ability and precision, and the second is
to evaluate the 3D electric ophthalmotrope as a teaching tools in the process
of teaching effectiveness compared with the traditional model in four aspects:
anatomical features, imitativeness, maneuverability and overall satisfaction.
All questions were answered using 5-point Likert scale (1=strongly disagree;
2=disagree; 3=neither agree nor disagree; 4=agree; and 5=strongly agree)[9]. The expert’s evaluation score is expressed in the form
of median.
Teaching
Effectiveness Evaluation of the 3D Electric Ophthalmotrope A total of 166 medical students, who
were registered for taking ophthalmology course, from Medical Collage of Xi’an
Jiaotong University, were recruited to attend in the students’ evaluation
progress in 2018. They were randomized divided into 2 groups: group 1 (n=83)
for 3D electric ophthalmotrope model, group 2 (n=83) for traditional
model. Randomization sequence was created using Stata 9.0 (StataCorp., College
Station, TX, USA) statistical software. Same teachers were assigned to teach
the group 1 students with the 3D electric ophthalmotrope model and eye anatomy
image, while the group 2 students with the traditional anatomical eyeball model
and the eye anatomy image to compare the teaching effectiveness.
Teachers briefly introduced eye
extraocular myopathy for 15min, and students studied the specimens by
themselves respectively with the two different models for 20min, then completed
the in-class quizzes[10] within 10min. A
prospective randomized controlled trial using specially designed questionnaire
examinations with 12 questions was conducted to evaluate the teaching
effectiveness of 3D electric ophthalmotrope on movement of extraocular muscles
compared to the traditional model. The questionnaires were about exercise
physiology of extraocular muscles, including identification of the direction of
movement of each extraocular muscle, and the theoretical knowledge and concepts
involved in the extraocular muscles. In addition, in the final exam, 4
questions were designed related to extraocular myopathy, and the scores of each
group of students were recorded and analyzed. The score data from the
questionnaires were recorded and analyzed to compare the differences of each
group as described previously.
Data
Analysis Continuous variables were expressed
as median. Wilcoxon tests were used to evaluate the simulation fidelity of the
models in the experts’ evaluations and the teaching effect of the 3D electric
ophthalmotrope. P<0.05 were considered as statistically significant.
Statistical analysis was performed with SPSS 19.0 software (USA).
RESULTS
The 3D
Electric Ophthalmotrope Model The 3D electric ophthalmotrope model
was constructed with the right eye as the prototype and was enlarged to a ratio
of 1:5. The volume of the model is 25×25×
Figure 3
Photo of 3D electric ophthalmotrope
A: Positive view;
B: The lateral view; C: The above view; D: Control buttons.
The 3D
electric ophthalmotrope’s model is composed of three parts: the control
circuit, the control panel, and the indicator. The control circuit consists of
integrated circuits controlled by a Philips LPC2368 microprocessor chipset (NXP
Semiconductors NV, Eindhoven, and the Netherlands; Figure 3D). The control
panel is composed of six buttons: A, B, C, D, E, and F (Figure
Experts’
Evaluation of the 3D Electric Ophthalmotrope The expert’s evaluation score for
the imitation effect of each extraocular muscle was expressed in the form of
media (Figure 4). All the experts strongly agreed that the 3D electric
ophthalmotrope could imitate the movement of the internal rectus, external
rectus, superior rectus and inferior rectus. Most experts agreed that the 3D
electric ophthalmotrope could imitate the movement of the superior and inferior
oblique muscles. All the experts agreed that the 3D electric ophthalmotrope
model was better than the traditional anatomical model for ophthalmology
teaching. The expert’s evaluation score is expressed in the form of median.
Wilcoxon tests showed significant differences between the traditional anatomical
model of eyeball and 3D electric ophthalmotrope in each index (P<0.05;
Figure 5).
Figure 4 Experts’ evaluation score
(media) of the movement of every extraocular muscle.
Figure 5 Experts’ evaluation score
(media) 3D motor-driven ophthalmotrope were
significant better than traditional anatomical model of eyeball with Wilcoxon
tests. aP<0.05.
Teaching Effectiveness
Evaluation of the 3D Electric Ophthalmotrope The teaching effectiveness showed
that the 3D electric ophthalmotrope has the advantage in ophthalmology
teaching. The scores of the students with the 3D electric ophthalmotrope model
were greater than those with the traditional anatomical model in the in-class
quiz and final quiz (P<0.05; Figure 6).
Figure 6 Medical student examination
scores (media) 3D motor-driven ophthalmotrope group
performed better than traditional anatomical model of eyeball group by Wilcoxon
tests both in the in-class tests and final examinations respectively. aP<0.05.
DISCUSSION
To our
knowledge, this 3D electric ophthalmotrope is the first instrument which
simulates the superior oblique muscle and inferior oblique muscle’s movement by
electric model. Since understanding the extraocular muscles movement is
difficult and frustrating for medical students, this model provides us an
efficient and effective tool for medical student to explain extraocular
myopathy. It simulates the extraocular muscle motion based on the theory of
conjugate muscle movements. It also simulates eye motion under each extraocular
muscle and the accompany movements of the rest of the extraocular muscles.
Moreover, it simulates the movements of the superior oblique muscles using
ligament instructions. This model is compact and easy to move, which makes
in-class application of this 3D electric ophthalmotrope possible.
As early as 1857, Christian Theodor
invented the world’s first ophthalmotrope[11].
Since then, several eye models have been reported to demonstrate different eye
positions with varying degrees of accuracy[12].
The Mims ophthalmotrope focused on the description of extraocular muscle
movements and energy requirements for the movements of different extraocular
muscles[13]. All of these ophthalmotrope are
mainly focused the anatomical structure, but they couldn’t imitate the movement
of ocular muscle automatically and the entire system was clumsy[14]. Reeh et al’s[15]
ophthalmotrope is the close to the present model, using motors to induce the
movement of the extraocular muscles. However, his model could only simulate the
movements of the superior rectus, inferior rectus, medial rectus, and lateral
rectus muscles, but could not make the movements of the superior oblique and
the inferior oblique muscles.
Our 3D
electric ophthalmotrope could substantially enhance the teaching of extraocular
muscle function. The students commented that this model was intuitive and vivid
and largely boosted their interest in learning and their memory of theoretical
knowledge. Moreover, the model helps them transform the theory to clinical
problems quite well[16-18] .
The specific model also has some
limitations. For example, promotion and application need higher cost and longer
time, and students’ study is limited by space and time. It may be greater for
better teaching effectiveness and wider dissemination, if computer software can
be combined with virtual simulation technology to make movement of the
extraocular muscle[19-20].
In summary, the 3D electric
ophthalmotrope promotes the teaching effectiveness of extraocular movement,
which could be operated easily by students in practice, with unique
authenticity and good sense of experience. In the future work, re-validation is
required with a large number of student samples and focus on the promotion of
this model in ophthalmology teaching and its application in various forms.
ACKNOWLEDGEMENTS
Foundations: Supported by the National Natural
Science Foundation of China (No.30901655); Shaanxi Provincial Key Research and
Development Program (No.2018SF-230).
Conflicts of Interest: Xiong L, None; Ding XY,
None; Fan YZ, None, Xing Y, None; Zhang XH, None; Li T,
None; Wang JM, None; Wang F, None.
REFERENCES