In comitant strabismus, which of the following findings is characteristic?

Explanation

## Comitant Strabismus: Key Features **Key Point:** In comitant (non-paralytic) strabismus, the secondary deviation equals the primary deviation. This is the hallmark distinguishing feature from incomitant strabismus. ### Definition and Pathophysiology Comitant strabismus results from an imbalance in the innervation of the extraocular muscles, not from mechanical restriction or nerve palsy. The deviation remains relatively constant in all directions of gaze. ### Primary vs. Secondary Deviation | Feature | Primary Deviation | Secondary Deviation | |---------|-------------------|---------------------| | **Definition** | Deviation of the affected (squinting) eye when the normal eye fixates | Deviation of the normal eye when the affected eye is forced to fixate | | **In Comitant Strabismus** | Equals secondary deviation | Equals primary deviation | | **In Incomitant Strabismus** | Secondary > Primary | Secondary > Primary | **High-Yield:** The equality of primary and secondary deviations is pathognomonic for comitant strabismus and helps differentiate it from paralytic (incomitant) strabismus at the bedside. ### Associated Clinical Features - Ocular movements are **full and free** in all directions (no restriction) - No diplopia in long-standing cases due to suppression or amblyopia - Constant deviation across all fields of gaze - Normal pupillary responses and accommodation **Clinical Pearl:** Diplopia is NOT always present in comitant strabismus because the brain suppresses the image from the deviating eye, especially if the deviation is longstanding or developed in childhood. ### Distinction from Incomitant Strabismus In incomitant (paralytic) strabismus: - Secondary deviation > Primary deviation - Restricted ocular movements - Diplopia is typically present - Caused by cranial nerve palsy (CN III, IV, VI) or mechanical restriction