Smartphones for Visual Function Testing

Portability is now a key feature of VF testing software.

VINAY A. SHAH, MD • HEMANG K. PANDYA, MD

Currently, approximately 96% of physicians use a smartphone as their primary device to support clinical communications.¹ Ophthalmology is a gadget-oriented specialty, and retina specialists are no exception.

In the past 25 years, each of us at some point became accustomed to carrying a phone, pager, digital camera, laptop computer, or personal digital assistant to keep in communication with the clinic, to document findings, to access medical information, and to keep ourselves organized. In 2006, Apple (Cupertino, CA) first introduced the iPhone, which has now revolutionized our interaction, integrating all of these devices into a single “phone.”

There are some 43,700 medical apps available in the Apple Store alone for physician and patient use.² However, patients should be aware that not all medical apps are genuine healthcare apps. Only approximately 54% of medical apps available on iTunes are genuine healthcare apps, according to a 2013 report.³ The same report stated that 69% of apps were intended for patients, while 31% were intended for clinical use.

Whether examining a patient in the emergency room or conducting an inpatient consult, there can be limited availability of ophthalmic testing tools. These consults utilize near vision cards, color plates, pupil gauges/rulers, penlights, optokinetic nystagmus (OKN) drums, and Amsler grids, to just name a few. The smartphone has the potential to combine these clinical evaluation tools into one simple interface.

While these tools may not replace office-based testing under ideal conditions, with appropriate standardization and acceptance of some variability in testing, they can be particularly valuable in the acute patient care setting.

In this article, we discuss the tools available for assessing visual function on mobile devices. For the purposes of this article, we will divide our discussion into tools for the physician and tools that patients can use themselves.

VISUAL ACUITY

The Eye Handbook (Cloud Nine Development, Kansas City, MO), EyeChart (Dok LLC, Austin, TX), and EyeChart RandomEyes (Dok LLC) apps are portable tools for assessing the visual acuity of patients (Figure 1, page 38). EyeChart RandomEyes changes the eye chart during the exam to prevent patients from committing the test to memory.⁴ The EyeSnellen app (Steve Colley, Perth, Australia) for the iPhone/iPad (Apple) allows users to measure VA using a portable Snellen chart installed on a tablet device. In one study, the authors concluded that Snellen chart function on the EyeSnellen app was equivalent to the traditional Snellen chart at measuring VA at a test distance of 6 m.⁵

Figure 1. Screenshots of various ophthalmic testing tools available as mobile applications.

REFRACTION

The Near-Eye Tool for Refractive Assessment (NETRA; EyeNetra, Somerville, MA) is a portable and inexpensive solution for estimating refractive errors in the human eye, utilizing a $2 clip-on eyepiece with a smartphone.^6-8 Expensive optical devices for automatic refraction utilize a Shack-Hartmann wavefront sensor. NETRA creates an inverse Shack-Hartmann sensor, based on a high-resolution programmable display, and it combines inexpensive optical elements, user behavior, and computational reconstruction.

The key idea is to interface a lenticular view–dependent display with the human eye at close range — a few millimeters apart. This platform is extremely sensitive to refractive errors, focal range, focusing speed, and lens opacity.

COLOR VISION PLATES

There are several apps that determine whether your patient has color vision deficiency. If so, there are apps that actually help measure the type and extent of the deficiency (Color Blindness Test, EnChroma, Berkeley, CA; Eye Handbook). Because the tool is on a smart phone, it will not undergo the usual “aging” of color plates, with faded colors and potentially inaccurate results.

VISUAL FIELD

Visual field loss can be seen with a variety of ocular conditions, such as glaucoma, optic neuropathies, and retinitis pigmentosa. VisualFields Easy (Figure 2), an app designed at the University of Iowa (Iowa City, IA), provides a rapid (3 min/eye), inexpensive (free on iTunes), and mobile assessment of visual field function.^9,10

Figure 2. VisualFields Easy: iPad-based app user interface.

Using suprathreshold methods, this app allows for the screening of gross visual field abnormalities within 30º of fixation horizontally and 24º vertically. Ideal for performing visual field screenings in remote areas, this app was found to have a 0.79 mean deviation correlation with Humphrey visual field analysis, and it generates a report that can be e-mailed.

CONTRAST SENSITIVITY–VARIABLE CONTRAST SENSITIVITY CHART

Significant loss of contrast sensitivity is common among patients with various diseases of the retina and optic nerve. Advanced diabetic retinopathy, glaucoma, and neurological disease are strongly associated with significantly reduced contrast sensitivity. The Variable Contrast Sensitivity Charts (King-Devick Test, LLC, Oakbrook Terrace, IL) for iPad are used to test VA (ETDRS) and contrast sensitivity (contrast range: 100% to 1.25%).¹¹

AMSLER GRID

There are many apps that have various Amsler grid available on the go, which is very useful in hospital settings. Some apps that could be used by the retinal specialist are Eye Handbook and the Macular Society app (Andover, United Kingdom).

OPTOKINETIC DRUM

An electronic optokinetic drum replaces the bulky handheld instrument with a mobile application that is easy to use at the bedside, to evaluate patients for neuro-ophthalmic disorders. The stripe speed is easily adjustable to elicit a response. Various apps have this function, including the Optokinetic Drum (OptoDrum, Linsay Associates LLC, Newton, MA) app and the Eye Handbook.

RED SATURATION

Evaluation of red saturation is important in analyzing optic nerve diseases, including the sequelae of optic neuritis. The electronic assessment of red saturation plates can be found in the Eye Handbook.

PUPIL EXAM

One other very useful use of the smartphone is as a light for checking the pupils. Several apps have a pupil gauge, which can very helpful to measure pupil size. One app that includes most of the above-mentioned functions is Eye Handbook (Figure 3), which is popular among eye care professionals and has more than a million downloads.^12,13

Figure 3. Eye Handbook home screen with various testing tools.

Eye Handbook has a testing section that provides a helpful resource for those seeing patients outside the office. These tools include the VA cards, Amsler grid, pediatric optotypes, duochrome testing, tests for color vision, contrast sensitivity, an OKN drum, pupil gauge, and the Worth 4 dot test.

VISION MONITORING

SightBook

SightBook (Figure 4) is a mobile app by DigiSight Technologies (Portola Valley, CA) that enables patients to evaluate their visual functions, such as VA, Amsler grid test for macular disease, and contrast sensitivity.¹⁴

Figure 4. SightBook and myVisionTrack: Vision monitoring apps that allow electronic sharing with physicians.

The app allows the user to store results in an online account, where the retina. physician can access them. Once an individual’s test data have been uploaded to the DigiSight Network server, both the individual and the designated eye doctor can access the information via an authenticated channel (the patient and physician must be registered with DigiSight).

SightBook is not approved by the FDA, so if a physician registers with DigiSight, he/should be aware that the legal onus to monitor the patient’s data may fall on his/her own office.

myVisionTrack Vision Monitor

The first ophthalmic smartphone app to be approved by the FDA, myVisionTrack (Vital Art and Science, Richardson, TX) may prove to be a useful tool for self-vision monitoring in patients diagnosed with AMD (Figure 4).¹⁵

Incorporating a proprietary shape discrimination hyperacuity test developed by the Retina Foundation of the Southwest, this app markets itself as an accurate, portable, and user-friendly system that enables patients with retinal diseases to quickly and efficiently test their own vision function at home and to share the results with their doctor to monitor the progression of their disease and treat it effectively.

It is necessary to mention that patients must have a physician-written prescription before this app can be accessed.

SCHOOL HEALTH VISION SCREENING

Based on guidelines and recommendations by the American Association for Pediatric Ophthalmology and Strabismus, Vision Screening (School Health, Hanover Park, IL), an iPad-based app, was designed for school health screening purposes.¹⁶ It features evidence-based, proportionally spaced eye chart designs and optotypes for screening and testing — both distance and near vision.

GoCheck Kids

Developed by ophthalmologists for screening purposes, GoCheck Kids (Gobiquity, Aliso Viejo, CA) is a photoscreening app designed for pediatricians to detect causes of amblyopia (myopia, hyperopia, anisometropia) in children beginning at six months of age.¹⁷

Utilizing the smartphone’s camera and flash, this app detects the red reflex and conducts software analysis to provide results regarding the child’s refractive state. The report generated from this analysis may be uploaded to a secure portal, thereby facilitating the transferring of records to the pediatric ophthalmologist’s office.

DOCTOR APP

Several ophthalmology practices now have developed and published their own personalized applications (eg, Neuro Eye of the Denver Retina Center). Several of these apps have testing tools that allow patients to test their vision, color vision, or Amsler grid with their app. If and when patients recognize a problem, they can contact their doctor directly from the app. These apps have several other functions, such as patient education material and appointment and medication reminders.

LOW VISION TOOLS: VISIONASSIST

The VisionAssist app (Slinkyware, Suffern, NY) was specifically designed to replace the handheld magnifier for patients with low vision needs.¹⁸ In particular, the designers of this app suggest that the magnification and lighting provided may assist patients with AMD, improving their ability to read in settings with dim lighting, such as when reading a menu in a restaurant or a roadmap at dusk. Also, utilizing Apple’s AppleTV compatibility, these images can be wirelessly projected onto a large screen television.

CONCLUSION

Many Americans believe doctors are using antiquated communications technology, with only a small minority of practices offering patients Web access to their health data or the option to schedule appointments via the Web, text, or e-mail.¹⁹

A study revealed a similar lag in the use of mobile healthcare apps. Almost all of the respondents who used a health app said it was improving their quality of life, yet only 16% of doctors were using these apps in their work with patients.²⁰ However, the report offered a positive prognosis. Almost half of the physicians were expected to introduce apps to their practices within the next five years.

The use of smartphones in the diagnosis of different ocular conditions has several limitations, mainly regarding the regulations and standardization of the performed tests. Usage of mobile devices to transfer patient data should be done securely using message encryption; appropriate documentation of patient consent must be obtained. Special consideration should be given to HIPAA and patient confidentiality.

Nearly all physicians are using smartphones to support clinical communications. These trends bode well for the use of smartphones and mobile devices for visual function testing.

There certainly are a variety of tools available to assist the clinician in hospitals and more remote settings, as well as to enable patients to screen and monitor their vision at home.

Smartphones have already made a great impact on ophthalmology and medical practices in general. The ophthalmic utility of smartphones continues to evolve and will assuredly continue to improve over time. RP

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