Standardized ETDRS - ESV-3000
The ESV-3000 ETDRS testing device has patented (Patent # 5,078,486) self-calibrated test lighting. The ESV-3000 device incorporates highly advanced LED light source technology. The auto-calibration circuitry constantly monitors the LED light source and calibrates the test luminance to 85 cd/m2 or 3 cd/m2. Other ETDRS testers are not standardized and have no circuitry to control the test lighting. They use "off-the-shelf" non-standardized fluorescent bulbs that require a bulb "burn-in" period. The bulbs must be constantly replaced and each time a bulb is replaced, there is an additional "burn-in" period. No testing can be accomplished during the "burn-in" period.
ESV-3000 Standardized ETDRS Viewer
The ESV-3000 is the only large-format standardized ETDRS testing device. The ESV-3000 allows testing up to 20/200 ETDRS Acuity at a test distance of 4 meters (The CSV-1000 has a smaller footprint and allows testing up to 20/200 at a test distance of 8 feet.). The device is operated by infrared remote control.
The ESV-3000 is designed specifically for clinical trials where large-format ETDRS testing (up to 20/200) is performed at 4 meters. Unlike other large-format back-lit devices for ETDRS evaluation, the ESV-3000 light level is calibrated and held constant, ensuring the automatic replication of testing light levels from different clinical trials locations as well as for evaluation before and after treatment. Other devices are not standardized and cannot provide consistent test lighting for ETDRS evaluation between locations or over time. A wide variety of ETDRS LogMAR tests are available, including Chart R, Chart 1, Chart 2, Tumbling E and many others.
The CSV-1000ETDRS allows standardized testing of ETDRS acuity at 85 cd/m2, the light level recommended by the FDA for vision testing. Many tests are available, including ETDRS Chart R, Chart 1 and Chart 2.
The CSV-1000ETDRS is smaller than other backlit systems for ETDRS testing and allows testing 20/10 to 20/200 at a distance of 8 feet or 20/5 to 20/100 at a distance of 4 meters. It is perfect for examination room use, where a 4 meter test distance is not available, or for clinical trials where testing beyond 20/100 is not needed, such as refractive surgery or IOL trials. Reversed ETDRS tests are also available for testing at a distance of 4 meters with a mirror.
The CSV-1000LH Symbol test face provides common symbols for the evaluation of illiterate or non-English speaking patients. The test is also widely used for the evaluation of children. The CSV-1000LH is in the ETDRS format. A patient prompt card is included.
The CSV-1000TumE test face provides a LogMAR test which presents the Letter E in various orientations. This test is very useful for evaluating illiterate or non-English speaking patients.
The CSV- 1000LanC test face provides a LogMAR test which presents the Landolt C in various orientations. This test is very useful for evaluating illiterate or non-English speaking patients.
The CSV- 1000HOTV test face provides a LogMAR test in which only four letters are used; H, O, T and V. This test is very useful for evaluating children or patients which commonly reverse the appearance of objects. These letters were chosen because all are symmetric along the vertical axis. A prompt card is provided.
See the CSV-1000 ETDRS for closer test distances.
Contrast sensitivity determines the lowest contrast level which can be detected by a patient for a given size target. Normally a range of target sizes are used. In this way contrast sensitivity is unlike acuity.
Contrast sensitivity measures two variables, size and contrast, while acuity measures only size.