Chart2020 uses ETDRS protocol or staircase approach.
Chart2020’s vision testing system allows you to test visual acuity accurately and easily. One of the tests it uses is the Electronic Early Treatment Diabetic Retinopathy Study (or (e)ETDRS) testing protocol, which fulfils ANSI standards. This protocol provides a visual acuity score that is comparable to the ETDRS chart score. This is an example of how advances in medical technology have allowed optometrists to enhance their testing methods.
Chart2020’s (e)ETDRS method has two phases – screening and threshold. During the screening phase the letters K, R, V, and D are used to quickly reach an estimated threshold. The threshold phase is more comprehensive, using all the Sloan letters. Each eye is tested separately and then together.
Chart2020’s (e)ETDRS test strategy has a comprehensive 70 character version. The (e)ETDRS test strategy tests from 20/200 to 20/10 in LogMAR steps with a score of 70 being equal to successfully reading all 20/10 letters and no misses on any larger lines.
The test begins with a screening phase to approximate the subject’s VA threshold followed by a detailed testing phase in which the approximated threshold is challenged with a “pool” of letters. The pool is comprised of letters at, higher and lower than the approximated threshold that are tested until both an upper LogMAR level (smallest line in which all 5 letters are successfully identified) and lower LogMAR level (largest line in which 0 of 5 letters are successfully identified) are defined.
At the conclusion of the vision testing a report is automatically generated with upper, lower and intermediary levels specified numerically and graphically, and the total (e)ETDRS score is calculated. These reports are detailed and accurate, and you can use them to aid you in diagnosis of patients. According to Kaiser’s 2009 study, ‘Visual acuity scores were significantly better on ETDRS charts compared to Snellen charts.’ Therefore using Chart2020’s ETDRS testing protocol will allow you to test visual acuity best, to the benefit of your patient.
You can also use the staircase method with Chart2020. Here, the patient is presented with one letter at a time. The system first determines approximate threshold rapidly, followed by a fine tuning to determine the exact VA.
If you are an optometrist who wants to use powerful advances in medical technology to better examine your patients, Chart2020’s vision testing is for you.