A Low-cost Virtual Reality Game for Amblyopia Rehabilitation page 1
A Low-cost Virtual Reality Game for Amblyopia Rehabilitation page 2
A Low-cost Virtual Reality Game for Amblyopia Rehabilitation page 3
A Low-cost Virtual Reality Game for Amblyopia Rehabilitation page 4

A Low-cost Virtual Reality Game for Amblyopia Rehabilitation

  • View

  • Download

Embed Size (px)

Text of A Low-cost Virtual Reality Game for Amblyopia Rehabilitation

  • A Low-cost Virtual Reality Game for AmblyopiaRehabilitation

    Angelo GargantiniDepartment of Engineering,

    University of BergamoViale Marconi 5 24044Dalmine (BG), ITALY


    Fabio TerziDepartment of Engineering,

    University of BergamoViale Marconi 5 24044Dalmine (BG), ITALY


    Matteo ZambelliDepartment of Engineering,

    University of BergamoViale Marconi 5 24044Dalmine (BG), ITALY

    m.zambelli3@studenti.unibg.itSilvia Bonfanti

    Department of Engineering,University of BergamoViale Marconi 5 24044Dalmine (BG), ITALY


    ABSTRACTThe paper presents the design and development of a mobileapplication realizing a video game that aims at treating am-blyopia by using a Google Cardboard. Google Cardboard isa low cost device able to reproduce virtual reality by meansof a smartphone. The proposed video game engaged the pa-tient in a car racing game and it displays the same image tothe eyes, but with some differences that stimulate the lazyeye more than the normal eye.

    Categories and Subject DescriptorsApplied computing [Life and medical sciences]: [Healthinformatics, Consumer health]

    General TermsMeasurement, Human Factors

    KeywordsAmblyopia, Cardboard, Rehabiliation, Android, Mobile games

    1. INTRODUCTIONAmblyopia, otherwise known as lazy eye, is reduced visualacuity that results in poor or indistinct vision in one eyethat is otherwise physically normal. It may exist even inthe absence of any detectable organic disease. Amblyopia isgenerally associated with a squint or unequal lenses in theprescription spectacles. This low vision is not correctable(or only partially) by glasses or contact lenses. Amblyopiais caused by media opacity, strabismus, anisometropia, and

    significant refractive errors, such as high astigmatism, hy-peropia, or myopia. This condition affects 2-3% of the pop-ulation, which equates to conservatively around 10 millionpeople under the age of 8 years worldwide [8]. If ambly-opia is not diagnosed and treated in the first years of life,the lazy eye becomes weaker and the normal eye becomesdominant. The traditional way to treat amblyopia is carriedout wearing a patch over the normal eye for several hoursa day, through a treatment period of several months. Thistreatment has some drawbacks: it is unpopular, not wellaccepted by the young patients, and sometimes can disruptthe residual fusion between the eyes.

    Our group has been involved in the use of computer tech-nologies for the treatment of amblyopia for several years.The project 3D4Amb1 exploits the stereoscopic 3D technol-ogy, that through glasses with LCD active shutters permitsto show different images to the amblyopic eye and the nor-mal eye. We developed some software both for amblyopiadiagnosis [3] and treatment that uses this kind of 3D tech-nology [6]. A form of treatment we have proposed, consistsin watching video clips with 3D glasses that realize a virtualvisual rebalancing [2]. In this work we plan to advance w.r.t.the existing treatments by using a much cheaper virtual real-ity device and to emphasize the activity to be performed bythe patients. Indeed, while patching and vision rebalancingare classified as passive method, other treatments which re-quire some activity on the part of the patients are classifiedas active. Active methods are intended to enhance treat-ment of amblyopia in a number of ways, including increasedcompliance and attention during the treatment periods (dueto activities that are interesting for the patient) and the useof stimuli designed to activate and to encourage connectiv-ity between certain cortical cell types. A good survey andassessment about active treatments and their efficiency canbe found in [5].

    The active treatment proposed by 3D4Amb consists in play-ing with interactive games or exercises, which will stream



  • Figure 1: 3D4Amb system with Google Cardboard

    binocular images. In this settings, the child plays with aspecial video game which will exploit the binocular visionto send to the lazy eye all the details while the normal eyewill see only a part of the game scene. To successfully com-plete the game or the exercise the patient must use the in-formation shown to the lazy eye (and possibly fuse it withthe information shown to the normal eye). In this way, theamblyopic eye is more stimulated and the fusion encour-aged. The game application must continuously monitor thesuccess rate of the game in order to adjust the difficultybased on the real capability of the player. It is well knownthat video games can be very useful for visual rehabilitation[1]. Classical examples of games found in literature, includePAC-MAN and simple car racing games [7]. In this work wepropose a simple car racing game.

    The classic use of a 3D system (like 3D glasses or the GoogleCardboard) is to provide different images to the two eyes ofthe same scene with viewing angles slightly out of phase,that correspond to the different points of view of left andright eye. This vision produces an illusion of depth of thescene and is the heart of virtual reality. The primary prin-ciple of the system is that the images shown to the two eyesare different but related.

    This principle can be used in practice also for the treatmentof amblyopia by sending two different images to the two eyes:to the amblyopic eye we will show the most interesting partof the frame of the clip (or game), while to the not amblyopiceye (or good) we will show the least interesting part. Theprinciple, in case of use of the Google Cardboard is depicted

    in Fig. 1. Since the patients are young children, we decidedto implement the diagnosis and treatment modules in a formof videogame, in order to make the treatment fun and notboring. The final aim of the project is to give the patients acomplete system for the treatment that can be used at home.In fact, a smartphone and an inexpensive Google Cardboardare enough to run the software presented in this paper.

    In this paper, first in Sect. 2, we describe the Google Card-boards and how they work. Then In Sect. 3, we introduceour mobile application that realizes the video game for am-blyopia treatment.

    2. GOOGLE CARDBOARDGoogle Cardboard is a virtual reality (VR) platform devel-oped by Google. It was created by David Coz and DamienHenry, Google engineers at the Google Cultural Institute inParis, in their 20%Innovation Time Off[4], and introducedat the Google I/O 2014 developers conference for Androiddevices. It consists of a fold-out cardboard with two lenseswhere the user must insert the smartphone (see Fig. 2). Theuser looks inside in order to see the images displayed by thephone. It permits a stereo vision by sending two differentimages to the two eyes. It works with different smartphonesand can be easily adapted to be used by children. The sys-tem proposed in this paper also works with other types ofVR viewers (e.g., Samsung Gear VR).

    Figure 2: Google Cardboard

    It is not an experience as the strap-on Oculus Rift headset,which requires a computer (and is still in development), or

    SamsungaAZs Gear VR, which costs $200 and only workswith the Galaxy Note 4. But it is an easy way to get a feelfor what is possible with modern virtual reality, and beyondthe low cost of the headset, most of the available apps arefree.


    The principle of using 3D for penalization of the normal eyein amblyopic children, as explained before, has been appliedin the game development for the treatment of amblyopia.The game is called Car Racing Cardboard (CRC) whichworks for the Google Cardboard and it is freely availableon the Google play store2.



  • Required hardware. The user must have an Android Smart-phone (with the CRC application installed), Google Card-board, or any other 3D VR glasses and earphone with con-troller (+, - and confirm) to play with the game.

    Figure 3: A simple game scene

    Game principle. As shown in Fig. 3, the game scene shownto the patient is divided by CRC in two parts, one for thehealthy eye (right eye in the figure) and one for the ambly-opic eye (left eye in the figure). The CRC decides whichimages send to the eyes depending on the type of treatmentsuggested by the doctor. In any case the lazy eye of thechild is stimulated to work and the healthy eye is not cov-ered. This is a positive aspect since the children does notinterrupt the merger between the eyes (it is a problem withthe occlusion treatment, which can disrupt the residual fu-sion).

    The brain of the patient has to combine the two imagesto view the complete frame successfully and perform sim-ple operations like identifying the incoming cars and movethe main car. There are a significant number of elementscommon to both images, to make sure that the patient canmerge them. The final frame is a two-dimensional repre-sentation since the objective is not to stimulate the stereovision of the patient (at least initially), but to make the eyesworking in different way.

    Game description. Before the beginning of game, the ap-plication allows the user to choose the lazy eye (left or right),in order to decide between two different views (penalize theright or left eye). The goal of the game consists in getting thehighest score possible. The gamer moves the main car (in thebottom of the view) in order to avoid obstacles (i.e. incom-ing cars in the opposite direction), and if it does not hit anyobstacle, then the score increases. When the score re