Spherical component <−1.0 D or >+3.0 D | Visual acuity with Kays or Sonksen logMAR | One or more lines difference between eyes (logMAR 0.1) or equal vision ⩽0.175 |
Cylinder power >1.5 D | Cover test | Any manifest deviation (constant/intermittent) or heterophoria with slow recovery; nystagmus |
Anisometropia of spherical component or of cylinder power >1.0 D | Ocular movements | Any limitation of ocular movements or any ptosis potentially covering pupil |
| Convergence | Reduced convergence (>10 cm) |
| 20Δ base out prism | Not overcoming prism with one or both eyes or delayed recovery with phoria seen on cover test |