Abstract
Abstract: :
Purpose: Traditionally, the Watzke–Allen Slit–Beam Test is used as a diagnostic tool for the detection of macular holes and to assess function after anatomically successful closure of the hole. Thusfar, the psychophysical parameters of this test are not well established. The present study introduces a more sensitive alternative line–test. Methods: Twelve patients (age 58–79, VA 20/40 to 20/130.) who had undergone anatomically successful macular hole surgery within the last five years were tested. The Watzke–Allen Slit–Beam test was performed as part of their follow–up exam. They were then shown a new Hyperacuity Line Test, displayed on a computer screen. A vertical line (3° in length, 1° in width), composed of a white centre with black borders (full contrast, sinusoidal transitions) was shown on a grey background (overall isoluminant display). Each trial consisted of two consecutively presented lines, shown in rapid succession for 100 msec each with a 600 msec interval. One line of each pair was a straight line while the other was distorted into a sinusoidal wave, creating a spatial frequency of 16 cpd. Their order was randomized and repeated 40 times. After each pair, patients were asked which of the lines appeared straight and which wavy. If the patient identified the lines correctly, the amplitude of the sine wave decreased, establishing their hyperacuity threshold. Results: All patients had a negative Watzke–Allen sign. Nonetheless, 33% (4/12) of patients (VA 20/40 to 20/130) perceived a clear break in the Hyperacuity Line display. Conclusions: A post–operative negative Watzke–Allen sign was contradicted by the Hyperacuity Line test in a third of patients with anatomically successful macular hole surgery. This new line test forms a practical and more sensitive addition to the assessment of retinal function after surgery. New parameters for a definition of functional success will be discussed.
Keywords: macular holes • vitreoretinal surgery • macula/fovea