Abstract
Purpose: :
In recent work (ARVO 2006), we reported on a new simple, portable, hand-held booklet test for the efficient measurement of spatial contrast sensitivity (CS) in adults and children. The test consists of high-quality printed sine-wave gratings contained within a spiral binder and held 40 cm from the subject’s eye. For each of the sets of 5 spatial frequencies (SF), gratings of decreasing contrast are presented and a threshold estimated for each SF, thus generating a subject’s complete contrast sensitivity function (CSF). Although the test was successful, it was bulky, required about 6 minutes to conduct, and was limited to assessment of near vision. Here, we report on a newer more compact version of the test which also permits testing of both near and distance vision.
Methods: :
The original test consisted of 22 x 28 cm sheets mounted in a spiral flip-binder. One half of each sheet contained a sine-wave grating with a given spatial frequency (0.75 1.5, 3, 6, or 12 cy/deg at 60 cm). For each SF set, contrast ranges from 33% to 0.6% in 0.21 log CS steps. The other half of the sheet contained a "control" (blank) grating with 0% contrast. The new test maintains all of the same specifications except that each sheet now contains 3 blank gratings and 1 target grating. This reduces the chance probability of detecting the target from 1/2 to 1/4, and thus reduces the number of required sheets to half. The second modification was that a second 4-choice booklet was developed to test CS at 3m. The SF and contrast values are identical to those used with the 60 cm booklet. 50 adults and 50 preschool children were tested monocularly with both the near and distance versions of the test, and for validation, adults were tested with the commercial FACT chart. Some adults were also tested with and without optical correction.
Results: :
82% of the preschoolers and all adults completed both tests. Compared to the prototype, test time for each test was reduced from 6 min to 3 min in adults and from 7 min to 4 min in children. All subjects showed interpretable CSFs. Adults showed consistent CSFs at both test distances, but children showed superior near CS. Adult CSFs also showed excellent agreement with the commercial FACT chart, both for corrected and uncorrected vision.
Conclusions: :
The new 4-choice near and distance CS booklets appear to be a significant improvement over the prototype test. They are more compact, portable, time efficient, and simple to administer. Moreover, the addition of a distance version of the test permits the clinical advantage of better differentiating among optical and spatial deficits.
Keywords: contrast sensitivity • clinical research methodology • pattern vision