M&S Technologies’ SmartSystem PC
Plus offers several commercially
licensed pediatric fixation videos.
 Konan Medical’s Chart2020
provides easy, one-touch
access to library content and
sequences on an iPad.

Computerized eyecharts are an integral part of the modern day optometric practice.

Visual acuity is the ability of the eye to see an image, measurable by identifying the angle between the eye and the smallest recognizable optotype. In clinical practice, visual acuity testing is a way to measure the clarity of central vision as well as the health of structures in the eye, such as the macula and lens. In recent years, computerized eyecharts have moved to the forefront of the visual acuity testing space.

Keeping up-to-date with the most current technology will create a professional atmosphere and elevate any practice in the eyes of patients and consumers. The contrast of computerized charts is often much higher than that of projected charts, thus maximizing visual acuity potential. Screen displays can be calibrated easily for any distance. Computerized charts also include a variety of optotypes for different types of patients. This diversity allows for more efficient management of all patients and especially pediatric or special needs patients.

The Snellen chart is the most commonly used visual acuity test and comprises rows of letter arranged from largest (at the top) to smallest (at the bottom). Also available on computerized eyecharts are Lea symbols, Tumbling E, numbers, and Landolt C. The convenience of being able to switch easily and quickly among these acuity measures is highly beneficial in a busy practice.

Another commonly used visual acuity test is the ETDRS chart. This one has the same number of letters per row for every sized optotype, equal spacing of rows and letters on a log scale, and individual rows are balanced for letter difficulty. The HOTV chart is a variation of ETDRS measured visual acuity, also available on computerized charts. Ultimately, the use of computerized vision charts makes it possible to switch back and forth between many types of visual acuity charts, as with all different optotypes.

The addition of video play in vision charts facilitates cooperation from pediatric patients. For example, during retinoscopy, ophthalmoscopy, and biomicroscopy, we can now hold the patient’s attention and therefore fixation for longer periods of time. In some situations during pediatric eye exams, the use of video can also be used as a reward for cooperation.

Today’s computerized visual acuity testing systems are much more than a method to replace a manual projector and slides. They represent an evolving technology that provides eyecare professionals with a robust array of visual stimulae. Most systems consist of a high-resolution LCD monitor, an integrated computer to handle the graphics processing, and a small handheld control unit. Some systems use Apple’s iMac computer, which is completely self-contained. Calibration software makes it easy to adjust the size of the test images for the design of the exam room. Computer-based acuity testing systems also offer the benefit of being upgradable as new software is released by the supplier.

Usually during routine dilation or cycloplegic exams, there is, inevitably, some period of waiting for the patient, either for drops to take effect or for the return of the doctor. Keeping children entertained in the office relieves stress from parents and makes for a better family experience. During InfantSee exams, for example, the video function can be used to capture attention and easily assess fixation preference, among other parameters.

During a distance cover test, a single optotype can be set to random cycle every few seconds. The cycle feature requires astute attention and accurate fixation which is highly beneficial for accurate cover tests. This is especially important for patients with strabismus. The optotypes of computerized reading charts can also be isolated or arranged in horizontal or vertical lines.

With computerized vision charts, it is also possible to randomize the optotypes. A specific example of where this is particularly useful is in the management of amblyopia. Children who are seen frequently enough are able to memorize the letters, compromising the validity of testing. It is also possible on computerized charts to quickly switch between standard Snellen sizes of optotypes to variations in between, which is particularly useful for letters at lower threshold optotypes because the standard sizes jump from 20/100 to 20/200, and then to 20/400. In amblyopic or low vision patients it is a major advantage to be able to more accurately differentiate acuity along that scale, for example, a 20/160 acuity.

With the computerized Lea and HOTV optotypes, the matching element offers a convenient solution to reliably test acuity in non-verbal or very shy children.
Low-profile, flat-screen monitors are usually connected to an operating computer that is discretely stored out of sight, creating a more open and clutter-free exam lane. This is in contrast to older model projection systems, which tend to take up more space at eye level in addition to the screen itself. One benefit of the manual projector is its usage in developing countries where computers may not be accessible, otherwise the computerized projector is definitely more up-to-date.

It is easy to train new staff to use computerized eyecharts. The software from most manufacturers is designed to be very user-friendly, and will always come with a user manual that can be very helpful in troubleshooting and finding quick shortcuts for the best use of the equipment. It is recommended that staff read the manual for full understanding of the capabilities of the computerized system. Having a cheat sheet available in each exam lane can also be helpful to maximize efficiency and minimize confusion while using the eyechart. This is particularly important while a patient is in the room because it will maintain the professionalism of the encounter for the patient.

As optometry continues to evolve, the equipment that we have available continues to develop and expand. Options today are much greater than ever before, and new challenges lie in selecting the options that will work best within a practice.

Konan Medical’s Chart2020 makes it easy for practitioners to access library content and sequences with a single touch. M&S Technologies’ Smart System PC Plus offers a range of features, including commercially licensed pediatric fixation videos. Other companies that make similar systems include Haag-Streit USA and Innova Systems.

To determine which system is best for your practice, a good starting point is visiting the manufacturer’s websites. Many have instructional videos and testimonials from colleagues. Checking in with customer service departments is another great way to have your questions answered. Finally, seeing the systems at conferences and meetings is often the best way to assess which system is right for your growing practice. OO

Katherine Shen is an associate at Specialty Eyecare Group in Seattle and Kirkland, WA. Sheila Morrison is a fourth-year student at Pacific College of Optometry, interning at Specialty Eyecare Group.


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