Building a Database of Results From People Without Eye Problems

Objective: To build a normative database for the Spaeth / Richman Contrast Sensitivity Test (SPARCS).

Background: Patients with glaucoma have diminished contrast sensitivity. SPARCS is a novel test designed to determine the contrast threshold in the central 5 degrees of vision as well as each of the 4 peripheral quadrants (superotemporal, superonasal, inferotemporal, inferonasal). It is performed on a standard computer with at least 1024 x 768 monitor resolution. The correct testing distance is 50 cm away from the computer screen. Appropriate refractive correction is used. Testing is performed in a room with standardized lighting (85 cd / m2) and no windows in order to minimize glare and reflections. Testing is performed monocularly with the non-tested eye covered by an eye patch. The purpose of this study is to build a normative database for SPARCS.

Study Design: Cross sectional observational study.

Methods: Healthy volunteers will be recruited from the Wills Eye Institute after obtaining informed consent following the principles of the Helsinki Convention. Approximately 320 people free of ocular disease will be recruited to form a portion of the normative database for SPARCS. A goal of 20 subjects per decade of life (10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80+) for both Caucasians and African Americans will be recruited. Other ethnicities will also be recruited, though without specific recruitment goals. Future study locations will help diversify the population of the normative database.

After agreeing to participate in the study, subjects will be assessed to determine if they qualify. Potential participants will be asked if they have any known eye diseases or decreased vision. Best-corrected monocular visual acuities will be assessed using an ETDRS visual acuity chart. A slit lamp examination will be performed to confirm good ocular health. Subjects will be excluded if they have any apparent ocular disease that affects visual acuity or visual function. For example, people with glaucoma, macular degeneration, or diabetic retinopathy will be excluded. Additional exclusion criteria includes: visual acuity 20/40 or worse; cataract grade 2 3+ or worse; posterior capsular opacity grade 2 3+ or worse; refractive error greater than +5 or -5 diopters; and incisional eye surgery within the prior 3 months.

After a person qualifies for the normative database, he or she will then take SPARCS. A trained technician will position the patient to the correct testing distance, check room lighting, and then explain the test. Subjects will be told to fixate on the central area and when ready, click the central area once with a computer mouse. Vertical dark bars will briefly appear in 1 of the 5 tested areas on the computer monitor. A subject will then move the mouse to the area the image appeared and click it once. When the subject is ready for the next image to appear, he or she will click again on the central area. Subjects are also instructed to guess where the image appeared if unsure. Vertical square waves of varying contrast levels will then continue to appear in a random pattern until threshold has been reached for each area. After the testing algorithm has been completed, the test will automatically end.

Each eye of an eligible subject will take the test twice after receiving instructions from a technician. The technician will remain in the testing room the first two times SPARCS is taken. A half hour later, the subject will then take SPARCS again without instructions from the technician and without the technician being present in the room.

The mean score and standard deviation of each area and the total score will be analyzed for age, gender, race, and lens status. Spearman correlations will be used to examine continuous variables and Kruskal-Wallis analysis for categorical measures. Test-retest repeatability will be assessed using the Coefficient of Repeatability and the Intraclass Correlation Coefficient.