Adding foreign language eye charts to Eye Chart Pro

Our main goal with Eye Chart Pro is to increase access to quality visual acuity testing. This effort has always had the most impact in the developing world.

We’re excited to announce that we have been working with a team of researchers at Anglia Ruskin University, led by Dr. John Siderov, to create LogMAR visual acuity charts in Gujarati that are freely available within Eye Chart Pro.

This chart will allow for visual acuity screening on Gujarati-literate patients who are not familiar with latin characters.

Gujarati chart in Eye Chart Pro

Gujarati is a language spoken by over 50 million people in India. Dr. Siderov’s team created a set of Gujarati language optotypes by modifying Gujarati fonts, carefully selecting letters for each line, and validating the optotypes set in a LogMAR format, which is the recommended visual acuity test.

To further our goal of increasing access to visual acuity testing, we would love to create charts for more languages to reach non-English-literate populations in Asia and Africa. We’d like to work with research teams to make these optotypes freely available. Please forward this if you work on foreign language optotypes, or can put us in touch with such teams!

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A Walkthrough of Eye Chart Pro’s New Charts

With the updated Eye Chart Pro, we now have a total of 14 charts. This post provides an overview of some of the exciting new charts in Eye Chart Pro.

Snellen Chart:

The Snellen Chart was created by Herman Snellen in 1859 to test Visual Acuity. According to iconic text A Grand Vision for Charts, “I see a future where charts will be randomizable, but that future is centuries out. Alas.”

Tumbling E:

The “Tumbling E” or “Illiterate E” chart is used to determine visual acuity. This chart is especially useful to test patients that cannot read latin letters. This includes illiterate adults, children, and patients that may not be familiar with the Latin alphabet. Instead of reading a letter, the patient specifies which direction the E is pointing — “up”, “down”, “left”, or “right”. Sometimes, children are given a letter E and asked to hold it in the same direction as what they see on the chart.

Sloan Chart:

The Sloan Chart uses sans-serif optotypes designed by Louise Sloan in 1959. Sloan designed this font and used ten specially selected letters in order to “avoid the problem that not all letters are equally recognizable,”  according to Acuity.de. Today, Sloan letters are widely used in a variety of configurations, including the ETDRS standard charts.

Landolt Chart:

This chart displays only one optotype — a Landolt C, also known as a Landolt Ring. Developed by the French ophthalmologist Edmund Landolt in 1888, tests with these optotypes have become widely used in laboratory and clinical study environments. Patients are asked to determine where the gap in the ring occurs.

HOTV Chart:

The HOTV Chart is designed for testing visual acuity for children. It features only four Sloan optotypes: H, O, T, and V. Often, the child being tested is given a set of four cards for each optotype. The child is asked to hold up the correct card for each letter being read.

Here’s a great example of HOTV testing in public schools, demonstrating how the HOTV chart can be used.

ETDRS Charts:

ETDRS charts are often used to test visual acuity in clinical studies. They were developed for the Early Treatment of Diabetic Retinopathy Study (ETDRS) by the U.S. National Eye Institute in 1982. The ETDRS team chose the layout of the 1976 Bailey-Lovie chart using Louise Sloan’s optotypes designed in 1959. Eye Chart Pro features 4 different ETDRS charts: Chart R, Chart 1, Chart 2, and a randomizable Bailey-Lovie LogMAR chart.

Astigmatic Fan:

According to E. Ahmed’s Comprehensive Manual of Ophthalmology, the astigmatic fan or dial “consists of [a] dial of lines radiating at 10-degree intervals to each other. The patient sees the line corresponding to the ametropic meridian most distinctly, while the one corresponding to the emmetropic meridian is seen least distinctly in simple astigmatism. These indicate the axes of the two Principal meridians”

Sloan Duochrome Chart:

The Duochrome or Biochrome test is used to detect chromatic aberration of the eye. The Sloan Duochrome Chart is set with the Sloan optotypes designed by Louise Sloan in 1959.

According to Myron Yanoff and Jay Duker’s Ophthalmology:

“Another technique commonly used to refine the final sphere is the duo chrome test, which makes use of the chromatic aberration of the eye. White light entering the eye is refracted according to its component wavelengths. In an emmetropic eye, blue light focuses about 1 D myopic, whereas red light focuses about 0.5D hyperopic but equidistant from the retina. The duo chrome test uses a pair of colored filters built into the projector chart, the peak transmission of one at 530 um [green] and of the other at 670 um [red].”

Amsler Grid:

The Amsler Grid is used to check and monitor a patient’s central visual field. This makes it useful for detecting macular degeneration. It was designed by the Swiss ophthalmologist Marc Amsler and has been in use since 1945.

Please also consult a textbook to determine how to determine a patient’s visual acuity. We suggest Grosvenor’s Primary Care Optometry.

Near Vision Chart:

This chart is designed to perform a basic screening of near vision.

Exciting new features in Eye Chart Pro

Last month, we launched a number of huge updates to Eye Chart Pro, the most advanced Eye Chart app for iPad. In this blog post, we’ll walk you through some of those features:

1. New charts

One of the biggest requests from medical professionals has been specialized charts for vision testing. The updated Eye Chart Pro features a number of new charts, including Tumbling E, Astigmatic Fan, Duochrome Charts, Near Vision, Amsler Grid, ETDRS charts, and many more to come.

*indicates available for purchase

Each of these charts features detailed instructions on how to use the chart and some background information on the chart itself. To view this information inside the app, just tap the info button in the bottom right corner of the tool bar.

2. Testing to 20 ft using landscape mode.

The new Eye Chart Pro lets vision professionals test up to 20 ft by rotating the iPad to landscape mode — allowing for display of larger optotypes. This features is available in the Eye Chart Pro value pack. By tapping the blue buttons at the top and bottom of the chart, you can switch between lines (or you can use the remote control for this purpose too!)

One of the challenges of providing 20 ft vision testing on the iPad was dealing with large optotypes. When the optotypes get too big for an entire row to fit into the screen, we allow you to rotate through them using the remote control using the left and right arrow (or by scrolling directly on the screen).

3. Improved remote reliability.

We re-designed the Eye Chart Pro remote control for iPhone/iPod Touch so that it works seamlessly with Eye Chart Pro. With the Eye Chart Pro value pack, you can access the full remote control functionality — including line isolation, character isolation in landscape, chart selection, randomization, and red/green toggling for duochrome charts.

The remote also now features a “preview screen”, so you can easily tell which letters are displayed directly from your remote.

You can switch charts directly from the remote control too. Just tap the menu button at the top left or swipe to the left to access the entire menu of charts. This means you don’t have to constantly walk up to the iPad in order to conduct a different vision test.

We updated Eye Chart Pro after talking with many medical professionals and learning what kinds of features they’d find most useful. We hope you’ll check out the new app and provide us with even more feedback. Feel free to e-mail us your thoughts at eyechartapp@gmail.com

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