Measurement of strabismic angle using the distance Krimsky test

To evaluate the correlation of the distance Krimsky test and the alternate prism cover test (APCT) for the distance deviation in patients with horizontal strabismus.

Forty patients with horizontal strabismus (20 esotropia and 20 exotropia) were included in this study. Patients with a variable angle of deviation, vertical angle over 5 prism diopters, impaired binocular vision, or poor cooperation were excluded. We instructed the patient to look a target 6 meters away, and applied a prism over the patient's dominant eye while flashing a light source 33 centimeters from the middle of both eyebrows. When the corneal light reflexes were located on the center of each cornea, we measured the angle of deviation. We defined this method as 'distance Krimsky test,' and the angle measured by this method was compared with the conventional Krimsky test and APCT at distance. We analyzed the accuracy and intra- and inter-observer reliability.

The angle of strabismus measured by the distance Krimsky test showed a significant agreement and correlation with the deviation angle measured by the APCT. We elicited the correlation gradient between the angle measured by the distance Krimsky test and the APCT. In addition, the distance Krimsky test showed significant intra- and inter-observer reliabilities.

The distance Krimsky test is expected to be more useful than the Krimsky test in measuring the distance angle of deviation for patients with strabismus in whom it is difficult to measure the angle of deviation using the APCT. The distance Krimsky test can be an accurate and useful test through the improvement of proficiency of examiners and the establishment of individualized normative data.