Which test measures the alignment of the eyes by comparing them with a red light source?

The Krimsky test is specifically designed to assess the alignment of the eyes using a red light source. This test involves placing a red light in front of the patient while the patient fixates on it, allowing the examiner to determine how the eyes align in reference to the light. If the eyes are misaligned, the reflection of the light will appear at different points in each eye, helping to indicate the direction and degree of misalignment. This method is particularly useful for detecting strabismus in patients, as it provides a clear visual evaluation.

The other tests listed serve different purposes. The cover test evaluates how the eyes function together by covering one eye and observing the other’s movement, which can indicate tropias and phorias. The Maddox rod test uses a series of red and white lines to assess binocular vision and can help in evaluating the presence of diplopia. The phoria test specifically measures the eyes' tendency to drift when not being used to fixate on a target, which can indicate latent strabismus. Each of these tests assesses different aspects of ocular alignment and binocular function but does not utilize a red light source for the comparison as the Krimsky test does.