Which condition is characterized by sluggish reaction to light and accommodation, typically presenting as unilateral?

The condition characterized by a sluggish reaction to light and accommodation and often presenting unilaterally is Tonic Pupil, also known as Adie's Pupil. This condition occurs due to a disruption of the ciliary ganglion, which affects the parasympathetic innervation of the iris sphincter muscle. As a result, the affected pupil is larger than its counterpart and shows a slow or absent response to light. In addition, accommodation (the eye's ability to focus on near objects) is also impaired, leading to difficulty in tasks such as reading.

In this context, the other options do not fit the description of sluggish reaction to light and accommodation in the same way. An afferent pupillary defect indicates a problem with the sensory pathway but does not specifically describe the accommodation issues characterized by a tonic pupil. Amblyopia involves reduced vision without any structural anomaly and does not inherently involve pupil reaction. The swinging flashlight test is a method used to evaluate for afferent pupillary defects, but again, it does not describe the specific sluggish reaction associated with a tonic pupil. Thus, Tonic Pupil is distinctly recognized for these particular symptoms.