Research On Active Digital Strabismus Measurement Method Through Image Processing

Strabismus is an abnormal phenomenon that two eyes can't look at the target at the same time.It is one of the most common visual disorders of preschool children.Strabismus makes the eyes not aligned correctly,affects the vision and depth perception of both eyes,and leads to amblyopia and even permanent loss of vision,which can be reversed at any age.In addition to vision problems,strabismus can also bring serious negative effects on children and adults' daily life,education,employment,etc.,so timely diagnosis of strabismus is very important.However,the traditional diagnosis methods of strabismus,such as coverage test and corneal reflex,are carried out by ophthalmologists by hand,which mainly depends on the experience of doctors,so that the results are subjective and the operation is complex.With the development of computer vision,image processing and line of sight tracking,eyes movement measurement technology has been paid more and more attention and has made great progress.It has become a hot topic that people begin to use eye tracking to study strabismus.In this paper,an active digital strabismus measurement method based on image processing is proposed.This method combines the theory of ophthalmic optics and image processing,and uses eye tracking technology to obtain the pupil position data of patients in nine points(nine directions).According to the data of pupil position,the strabismus characteristics are analyzed.Based on this method,the coordinate system of strabismus measurement is established and standardized,and the corresponding squint measurement instrument is designed and built.The algorithms of image filtering,image increasing,image binarization,edge extraction,pupil center target segmentation and extraction are studied,and the corresponding strabismus measurement software system is designed.According to the principle that long time single eye covering can break the fusion image of both eyes,it can automatically diagnose strabismus and calculate the angle of strabismus.In addition,the system also actively obtains the pupil position data of patients in nine points of vision(nine directions),and obtains 2x9 groups of pupil data of left and right eyes in ninedirections.According to the data characteristics of the pupil position of both eyes,the correlation between strabismus and extraocular muscles was analyzed by using the track deviation of left and right eyes and the distribution of viewpoint.Three subjects were tested with a standardized strabismus instrument,and their deviation angles were measured.In the experiment,we found that the trajectory deviation of the healthy subjects' binocular movement was very small,and the viewpoint distribution was concentrated,which coincided with nine fixation points.Strabismus patients' trajectory deviation is large,the viewpoint distribution is discrete,and they can't look at some directions well.There may be relaxation in the right inferior oblique muscle of subject 3.The results show that the strabismus measurement method proposed in this paper has repeatability,can effectively measure the angle of strabismus,and can provide clinical data related to strabismus and extraocular muscles.