Teaching case. After six months of occlusion, acuity in the amblyopic eye has gone from 20/80 to 20/30. The family is celebrating. Worth 4-Dot at near — suppression; stereopsis not detectable. This is not "treatment failure". It is a different floor of function. If the resident did not measure binocularity at the start, they do not know what has changed: acuity, suppression — or nothing binocular at all.
The set the PPP considers meaningful.
- Worth 4-Dot — sensory fusion and suppression. Four dots: two green, one red, one white. The answers "four / three / two / five" are read as fusion, suppression of one eye, diplopia. The test is crude and depends on understanding, but in the clinic it catches what an acuity line does not.
- Randot / preschool Randot / Titmus — stereopsis of varying coarseness. The PPP names the Randot as an instrument for assessing stereopsis. High-grade stereopsis is associated with normal alignment. Absence of stereopsis in a three-year-old may be amblyopia, strabismus, or the child not having understood the task.
- Prism bar / rotary prism — motor fusion, fusional reserves.
Order: sensory testing before dissociation. Then cover/uncover for tropia, alternate cover for the total deviation (with the latent component), at distance and near, on an accommodative target. Versions and ductions, including oblique ones. In an infant — the oculocephalic ("doll's head") manoeuvre and observation of spontaneous movements if the child does not follow a toy.
Why this changes management and not only "the completeness of the examination".
- High-grade stereopsis with "20/40 amblyopia" makes you re-check whether the deficit has been overestimated by a poor test, and whether the difference is refractive without suppression.
- Suppression with almost equal acuity explains why the family does not see "depth", although the chart is reassuring.
- The appearance of diplopia during occlusion is a signal to stop treatment temporarily and monitor alignment (this is already the PPP table for adjusting therapy). Not "patch even harder until they get used to it".
- In a strabismic child the angle can change in either direction during amblyopia treatment: in ATS1 new strabismus and resolution of existing strabismus both occurred; the PPP notes that in some children strabismus worsens with occlusion, and in a comparable proportion it improves. Without a baseline measurement you cannot distinguish the effect from the baseline.
What binocular tests do not do. They do not replace acuity, do not make a diagnosis of amblyopia on their own, and do not prove that a particular digital method "restored binocularity" until this has been measured in the same protocol as acuity. The 2022 Cochrane review of binocular treatment states directly: there were no data on change in stereopsis and contrast in the included RCT.
Boundary. The course does not teach the interpretation of every synoptophore degree and does not cover anomalous retinal correspondence as a separate discipline. For amblyopia it is enough to: measure fusion, stereopsis and the angle before treatment, with the same tests at follow-up, and not confuse a gain in lines with restoration of the two eyes as a system.