Macular Degeneration – Clinical Management
Contrast sensitivity (CS) provides an accurate and sensitive way to evaluate loss of vision with macular degeneration and to measure the stabilization or improvement in vision with treatment. The standardization of the CSV-1000E provides a means to consistently measure visual function in ARMD so that the results are easy to compare to age-related population norms and from visit to visit. Since ARMD can affect vision over very long time periods, the standardization of test conditions is key to consistent measurements and the understanding of any change in vision for these patients due to disease progression or treatment.
This CS graph shows the results for a typical early ARMD patient. Note the patient’s CS is below the normal range for his age group for Rows C and D.
Early Macular Degeneration
Early in the ARMD disease process, patients can begin to lose central vision, but retain good acuity. The typical early ARMD patient will show losses in contrast sensitivity in the higher spatial frequencies (12 and 18 cpd) before any change in high contrast visual acuity and often before distortions in vision can be detected with an Amsler Grid. The CS graph to the right shows the results for a typical early ARMD patient. Note the patient’s CS is below the normal range for his age group for Rows C and D.
Nutritional Therapy for
Data suggests that patient vision for those with early ARMD can be improved by treatment with certain supplements. Considerable work has been done with lutein supplements and the related changes in contrast sensitivity. The bar graph below shows data from Stuart Richer and his team based on a placebo controlled study where patients were treated with lutein supplements. ARMD patients treated with lutein and lutein-A (lutein with additional carotenoids, antioxidants, vitamins, and minerals) showed significant improvements in contrast sensitivity compared to those treated with a placebo.
The bar chart of CSV-1000E results from Stuart Richer et al showing before and after nutritional therapy for ARMD patients. Note the significant improvement after lutein treatment at 3 and 12 CPD and after lutein-A at 3, 6, 12 and 18 cpd.
The bar chart of CSV-1000E results from Stuart Richer et al showing before
and after nutritional therapy for ARMD patients. Note the significant
improvement after lutein treatment at 3 and 12 CPD and after
lutein-A at 3, 6, 12 and 18 cpd.
Typical AMD Patient CS Results
The patient has CS scores below the normal range when ARMD is detected and then after supplementation, the CS recovered into the normal range.
This graph shows the typical clinical result for a patient who has been successfully treated with a vitamin or nutrient supplement. Note that the patient has CS scores below the normal range when ARMD is detected and then after supplementation, the CS recovered into the normal range. Clinical use suggests that a minimum of a three to six month time period is needed to detect improvements in vision after supplement treatment.
For more advanced cases of macular degeneration where visual acuity has already been significantly affected, letter contrast sensitivity (as opposed to sine-wave contrast sensitivity) is a better measure for the patients. For these patients, the Evans Letter Contrast Test (ELCT) is a better measure for visual capability and improvement as opposed to the CSV-1000E. Once a patient has lost 2 to 3 or more lines of acuity, his or her ability to see smaller low contrast objects at a distance of 8 feet becomes diminished, and a larger higher contrast range of test targets is needed to accurately evaluate vision.
ELCT (Evans Letter Contrast Test)
For testing an ARMD patient with the ELCT test, place the patient at 1 meter and ask him or her to read down the chart starting in the upper left hand corner (ie at the highest contrast level). The score on the ELCT test can then be used to quantify the vision loss of the patient from a real-world perspective and to establish a baseline to evaluate further disease progression or to measure improvement with treatment. In most cases, changes in contrast sensitivity can be detected with the ELCT three or more months before any change in vision can be detected with high contrast acuity. The ELCT uses standardized test lighting, similar to the CSV-1000E, and thus provides an excellent platform to obtain consistent test results for patients for comparison over time or to measure the improvements with treatment.
For patients with early ARMD (20/50 or better), use the CSV-1000E at a test distance of 8 feet to evaluate the disease progression or improvement with treatment. For more advanced patients, it is best to use the ELCT.