Not a feature of paralytic squint
**Core Concept**
Paralytic squint, also known as paralytic strabismus, is a type of strabismus caused by paralysis or weakness of one or more extraocular muscles. This condition disrupts the normal alignment of the eyes, resulting in double vision and other visual disturbances.
**Why the Correct Answer is Right**
The correct answer is one that does not describe a characteristic feature of paralytic squint. In paralytic squint, the affected eye deviates in the direction of action of the paralyzed muscle, due to the unopposed action of the opposing muscle. This results in a characteristic pattern of eye movement, which is a key feature of the condition. Additionally, patients with paralytic squint often experience double vision (diplopia) due to the misalignment of the eyes.
**Why Each Wrong Option is Incorrect**
**Option A:** **Heterotropia** - This is actually a feature of paralytic squint, as the affected eye deviates from the normal position of alignment.
**Option B:** **Diplopia** - This is also a feature of paralytic squint, as the misalignment of the eyes causes double vision.
**Option C:** **Concomitant strabismus** - Paralytic squint is actually a type of non-concomitant strabismus, as the deviation is not present at all gaze positions.
**Clinical Pearl / High-Yield Fact**
A key feature of paralytic squint is the presence of a "head turn" or "head tilt" to compensate for the deviation, which can be a useful clinical clue in diagnosis.
**Correct Answer:** D. Concomitant strabismus.