Nystagmus blockage syndrome (NBS) is characterized by which combination of findings?

• A Infantile nystagmus, esotropia, and dampening of nystagmus on adduction (near fixation) ✓
• B Infantile nystagmus, exotropia, and worsening of nystagmus on convergence
• C Spasmus nutans with head nodding and monocular nystagmus
• D Acquired pendular nystagmus with visual loss from multiple sclerosis

Explanation

Nystagmus blockage syndrome occurs when a child with infantile nystagmus adopts an esotropic posture (convergence/adduction) to dampen nystagmus amplitude and improve visual acuity. On examination: infantile nystagmus is present, there is manifest esotropia (typically large angle), and the nystagmus decreases or ceases in adduction. The esotropia is secondary to the nystagmus-blocking mechanism, not primary strabismus. Treatment includes correcting refractive error; surgery is considered to shift the null point and reduce the anomalous head position.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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