Final answer:
To assess the parallel alignment of the eyes, eye movement can be tested for proper conjugate movements and convergence. Failure of one eye to move properly may indicate internuclear ophthalmoplegia, while improper convergence may suggest issues with the accommodation-convergence reflex.
Step-by-step explanation:
Assessing the parallel alignment of the eyes can be done by testing eye movement. One way to do this is by having the patient track the tip of a pen as it is moved through their visual field. The examiner will observe for proper conjugate movements of the eyes, where both eyes move in the same direction at the same time. If one eye fails to move properly while the other does, it can indicate a condition called internuclear ophthalmoplegia, which can result in double vision.
Another aspect of testing eye movements is to assess convergence, which is the movement of both eyes towards a closer stimulus. This can be done by moving the pen closer to the patient's face and observing if both eyes adduct, or move inward, towards the stimulus. This movement is controlled by the medial recti muscles and is part of the accommodation-convergence reflex.
To summarize, the parallel alignment of the eyes can be assessed by testing eye movement and observing for proper conjugate movements and convergence. Failure of one eye to move properly can indicate a condition called internuclear ophthalmoplegia, while improper convergence may suggest issues with the accommodation-convergence reflex.