Abstract
Purpose: :
Currently, there are no clinically oriented tests for the comprehensive measurement of spatial contrast sensitivity (CS) in young children, especially those under theage of 5. Recently, we (Adams et al, ARVO 2009) developed a new prototype that combines the benefits of sine-wave technology with the clinical familiarity of Landolt symbols to assess CS in a small sample of preschool children. The measurement of CS is considered to be an important aid in the detection and monitoring of pediatric visual and neurological disorders, most notably neuro-ophthalmic pathology, refractive error, and amblyopia. Here we evaluate an improved version of the sine-wave Landolt test for the purpose of establishing normative CS data for the critical preschool years.
Methods: :
The latest version of the sine-wave optotype test consists of 6 charts, each containing rows of Landolt Cs which, from the outside to the inside edge of each C, modulate sinusoidally at 1 of 6 spatial frequencies (0.37, 0.75, 1.5, 3, 6 and 12 cy/deg). The average luminance of each sinusoid matches the chart’s background, and with each successive row, optotypes decrease in contrast from 40% (2.5 CS units) to 0.5% (200 CS units) in equal log steps. 110 3- to 5-year old preschoolers and 65 adults (M = 27yrs) were tested monocularly at 3m with all 6 charts. For comparison, adults were tested with commercially available FACT and Vector Vision sine-wave CS tests.
Results: :
95% of the preschoolers were capable of completing the entire test and each ofthese children generated an interpretable contrast sensitivity function (CSF). Test time averaged 6 min, but decreased significantly from 3 to 5 years of age. Distributions of CS at each spatial frequency were distributed normally at each age, increasing slightly from a mean (across SF) of 38 CS units at 3 years to 51 units at 5 years. In comparison, adult CS averaged 66 units, a value very consistent with both the commercial FACT and Vector Vision CS tests.
Conclusions: :
This new sine-wave Landolt C test of contrast sensitivity appears to be a successful and time-efficient tool for measuring full-spectrum contrast sensitivity in a sometimes difficult pediatric population. The ease of responding to the Landolt target yields both definitive responses and clear estimates of contrast thresholds in both children and adults. Moreover, the flexibility in the design of the Landolt target should allow it the additional feature of estimating a patient’s high and low contrast visual acuity.
Keywords: contrast sensitivity