BHHT and parks 3 step

Question 1

BHHT

Answer 1

Tests vertical strabsmus, diffrenciate between SR and SO palsy

Head tilt to affected side - If hypermetropia increases sup oblique palsy plesent

Head tilt to unaffected side - Little difference in deviation, therefore contralateral superior rectus.

Positive result >5 Prism diopters result from eye to eye

Performed at 3m so both muscles are not favoured

Question 2

Parks 3 step

Answer 2

Covertest performed in primary position

Alternating Cover test in dextro version and laevo deprerssion - Shows greater vertical deviation

BHHT then performed, increasing hyper deviation noted