Many ophthalmologists find themselves performing consultations away from the office or doing exams in emergency rooms where ophthalmic test equipment isn't readily available. Now, however, with the advent of devices such as the Apple iPhone and the Google Android, physicians can carry many vision tests right in their pockets. Patients with certain ocular diseases can also use their smartphones to perform regular checks of their own vision between office visits in order to stay on top of a problem.

Here's a look at several of the more popular vision testing applications for the iPhone. Unless otherwise noted, all of the applications are available in the Applications section of the Apple iTunes Store.

    • The Eye Handbook (Digital Medicine). This program, available for the iPhone and iPod Touch, was created by a group of ophthalmologists led by Ken Lord, MD, a fourth-year resident at the University of Missouri-Kansas City's Vision Research Center, and Vinay Shah, MD, a retinal fellow at Detroit's Kresge Eye Institute.

"We designed it for the eye-care professional," says Dr. Lord. "There are 10 different vision-testing modalities in the application. In addition to near-vision cards, there's color vision, Amsler grid testing, a pupil size gauge and others."

"We also have different kinds of vision testing, such as optotypes, rather than letters, for illiterate patients or kids," says Dr. Shah. "We have the HOTV test, which a four-year-old could use once trained in those four letters, and the tumbling E test that an illiterate person could use to tell you which way the E is pointing."

Though larger optotypes could be used on the application for testing distance vision, Dr. Lord thinks the nature of the device lends itself to near-vision testing. "I think the utility of distance vision testing isn't really clear. Who's going to break out a tape measure and go to a standard distance of 15 feet to test vision with an iPhone? I don't think anyone will do that. But when you're trying to get a good visual acuity in a consultation or an emergency room, it's ideal for that."

The actual intended use of the Eye Handbook application, says Dr. Lord, is as a comprehensive tool and reference for eye-care professionals to treat and diagnose patients. So, in addition to the vision tests, it has an animated fixation target to use during exams of children, a penlight function that physicians can use to test pupil response in a darkened room, an index of hundreds of ophthalmic instruments and descriptions of how they're used, an ICD-9 code tool, a list of 600 ophthalmic disease eponyms and a pharmacopeia that's specific to ophthalmic drugs.

There's also a new version of the application that's slated to be released some time this year, and a version for devices that use Google's Android operating system is in the development stage. "The next version will have a large section on the lenses ophthalmologists use for exams and for laser treatments that will explain the parameters of the treatments and which lenses are best to use for which treatment," explains Dr. Lord. "The new version will also have a section with advice on how to workup a patient who presents with a particular diagnosis, such as which tests to order for someone with ocular inflammation."

The Eye Handbook is free, and it requires iPhone Operating System 3.0 or later.

    • Eye Test (Bokan Technologies). Bokan Technologies says its Eye Test application is useful for patients and doctors who need to routinely perform visual acuity testing. It has tests for near acuity, color vision and acuity at distances of 0.5, 1 and 1.5 meters. The Eye Test also offers some entertainment in the form of optical illusions, which come complete with explanations of how they work. The application's Snellen tests also use a recording feature that allows users to monitor their test results over time and note any changes. The Eye Test costs 99 cents and requires iPhone OS 2.1 or later.

    • Macula Tester (Sabina Technology). Sabina Technology says that, though the Amsler grid card is a good tool for catching macular disease, one of its major flaws is that patients often forget to use it or sometimes even lose it altogether. With this application, the company says, not only can patients record the areas on the digital grid that appear distorted, they can save them for comparison with subsequent tests, and can even set a reminder that will prompt them to re-take the test over time. A video demonstration of the Macula Tester is available at maculatester.com. The application costs $2.99, a portion of which will be donated to a philanthropic eye-care organization such as the EyeCare Foundation or the Macular Degeneration Partnership.

    • iVFQ (e-Agent). This is a digital quality-of-life, visual function questionnaire based on the National Eye Institute's venerable Vision Function Questionnaire 25, and it's intended for use in a physician's practice. Stephen Sinclair, MD, a retinal specialist from Media, Pa., says he developed the iVFQ "to try to get the retina doctor to better understand the outcomes of his treatments, and to bridge the gap between himself and the low-vision doctor." He says he felt there was a need for this because retina physicians seemed more focused on visual acuity and whether or not there was subretinal fluid remaining after their treatment, rather than whether the treatment had any effect on a patient's quality of life. He says low-vision referrals seem to be declining as well, which may not be good for patients who struggle with daily activities. "Why might they be declining?" he asks, "For a couple of reasons: First, before Avastin and Lucentis, treatment effects lasted two to three months; now they last a year to two years. 

With that type of timeline, it's hard for a retina doctor to do an about-face and say to the patient after two years, 'I think you should go see a low-vision doctor.' Also, many of us are tied to our primary ophthalmologist or optometrist for referrals, so we feel kind of uncomfortable sending a patient to a low-vision doctor rather than the primary eye-care provider."

Dr. Sinclair says he hopes the iVFQ, when administered to a patient in the office, will give the retinal physician a better handle on just how low a patient's vision is by seeing how it affects the activities of his daily life. To take the test, which is usable by patients with as low as 20/100 vision, the doctor enters the patient's information and then allows the patient to answer the questions via the touch screen.

The iVFQ, seen here, is aimed at giving retinal specialists a better understanding of how macular disease affects their patients' everyday life.

Then, as long as the device is able to connect to the Internet, the results are transmitted to a secure server and, within five minutes, the doctor receives an assessment of the patient along with "helpful recommendations to assist patients in managing their vision problems."

The iVFQ costs $49.99, and requires a second-generation iPod Touch or an iPhone running OS 3.1.2 or higher.

    • Eye2Phone (Renato Neves, MD). This application was originally dubbed Eyephone, but the name had to be changed because it sounded exactly like iPhone. It's a vision-testing application developed by an ophthalmologist in Brazil to allow eye-care providers and students to perform routine tests. Tests provided include:

"The tests are all calibrated for the small screen," says Dr. Neves. "That's why we couldn't make a full Distance VA Chart, only the angular E chart. However, the near vision can be pretty accurate and it is important to assess vision loss.

"After releasing the app last year we had more than 1,000 suggestions for version 1.1, and the version that was released reflects these ideas," continues Dr. Neves. "Many requests were made for different features, but this version is for eye tests. However, we may develop a version for help with antibiotic eyedrop preparation and differential diagnosis."

The Eye2Phone requires iPhone OS version 2.0 or higher, and costs 99 cents.