Strabismus and ocular motility disorders — formative SAQs

SAQ 1 (10)

A three-year-old is brought in because the right eye has been turning inward over the past three months. The parents describe a turn that was intermittent at first but is now present most of the time, worse when the child is tired. The cover-uncover test shows a right esotropia, and the angle is the same when the child looks to the left, to the right and at near. The alternate-cover test measures a slightly larger deviation. Visual acuity is reduced in the right eye. [1] [5]

a) What is the most likely diagnosis, which single investigation is most important, and how does its result guide the first treatment? (3 marks) [5] [2]

b) Outline the fixed sequence of definitive management, naming each step and explaining why the order matters for binocular vision. (3 marks) [1] [11]

c) The right eye has reduced acuity. State the two main amblyopia treatment options, how they compare for moderate amblyopia, and the principle that governs their timing relative to surgery. (2 marks) [9] [11]

d) Explain why a high accommodative convergence to accommodation ratio subtype might require a bifocal add, and how it differs from the purely refractive subtype. (2 marks) [5]

SAQ 2 (10)

A previously well eight-year-old presents to the emergency department with three days of horizontal double vision. Examination shows a left eye that cannot abduct past the midline, an esodeviation that is much worse when looking to the left and at distance, and a normal fundus. There is no significant refractive error on a brief retinoscopy and no history of head injury. [6] [1]

a) Classify the deviation as comitant or incomitant and justify your answer from the gaze-dependent angle. What is the clinical implication of this classification? (3 marks) [1] [6]

b) State the most likely anatomical and localising diagnosis, list the serious causes you must exclude, and name the urgent investigation. (3 marks) [6] [2]

c) Contrast this child's plan with that of the three-year-old in SAQ 1, explaining why one child is managed with glasses and the other with imaging and referral. (2 marks) [1] [5]

d) During the assessment you also examine a one-year-old referred for a "turned eye" who has broad epicanthal folds, a normal cover test and symmetrical corneal light reflexes. Name the diagnosis and the management. (2 marks) [1] [2]