Retinal Acuity Meter
Available charts: Letters, ETDRS logMAR, Numbers, Isolated E
The Retinal Acuity Meter combines familiar principles into an uncomplicated calibrated system that accurately measures retinal acuity in eyes with clear lenses, cataracts, cloudy posterior capsules, maculopathy, and glaucomatous field loss. It identifies the cause of central vision loss. It is so simple that entry level technicians can measure potential acuity reliably in only one minute. Patients find it easy.
The RAM® viewed through the RAM Pinhole Clip™ accurately forecasts retinal acuity. The RAM® consists of a brightly illuminated near card with letters indexed from 20/20 to 20/200 in 9 increments. The device is battery powered, hand held, and comfortably fits into a pocket.
Earlier models of this technology were the Illuminated Near Card or INC and a small version was the Mini-INC. The RAM® has retained the critical testing parameters of the INC and the Mini-INC; namely, identical letter size and brightness, so that all research data obtained with these instruments are applicable to the RAM®. The RAM® has the following advancements: an ergonomic molded faceplate with a built-in cradle for the retractor, an improved disc rotating mechanism, high resolution digital photographic lettering, and clearly visible indices to identify the level of acuity being tested.
Albert Einstein said, "Things should be made as simple as possible, but not any simpler." We believe the RAM® fulfills this idea. The RAM® technology is a combination of three basic optical principles: small aperture pinhole, correct visual angle, and bright illumination. The small aperture pinhole places the eye in almost universal focus and near correction is added to maximize resolution. Multiple pinholes allow the patient to select the clearest view through the cloudy media. The letters at 40 cm subtend the same visual angle as Snellen letters at 20 feet. The bright illumination more than compensates for the reduced illumination by the small aperture pinhole and the media opacity.
Investigators have found that the average testing time is 1 minute in eyes with and without glaucomatous field loss (Asbell, et al.). The device has been shown to accurately predict post-operative vision in eyes with opaque posterior capsules (Hofeldt) and in eyes with cataract that have normal or abnormal macula (Hofeldt and Weiss). The RAM has been clinically tested for over 10 years.
Triage: When a patient presents with vision loss, maculopathy can be easily ruled-in or ruled-out as the cause of the vision loss and prevent costly and time-consuming testing.
Pre-operative Potential Vision Test: The RAM® is a valuable predictor of post-operative acuity in eyes with cataract or opacity of the posterior capsule. In eyes with cataract and maculopathy, the test can determine what portion of the vision loss is due to cataract and what part is due to maculopathy. Surgical delay can be avoided in eyes with maculopathy when the retinal acuity is found better than expected. Conversely, disappointing outcomes can be predicted and prevented.
Monitoring Macular Function in Co-morbid disease: While following patients with maculopathy and cataract, the RAM® can determine what portion of the vision loss is due to cataract and what part is due to maculopathy.
Documenting Visual Acuity: The RAM® quickly establish the Best Visual Acuity without formal refraction.
4 Determines if the vision loss is due to abnormal media or macula
4 Accurately forecasts post-operative vision prior to cataract surgery or YAG laser capsulotomy
4 Prevents surgical delays and unexpected poor outcomes
4 Allows the patient of visualize the benefit of surgery prior to the operation
4 Start to Finish in less than 1 minutes
4 Easy for patients and technicians
4 Hand-held and fits into a pocket
Dimensions: 4 x 2 ˝ x 7/8 inches
Weight: 5.5 oz
Bulb: 3 watt CCFT
Power Supply: 2 AA batteries