Background: The oculomotor analemma hypothesis proposes that the structural misalignment between the pupillary axis and the foveal axis — quantified by angle kappa — is the torsional parameter of a double dynamic oscillation with formal structure analogous to the solar analemma. The hypothesis predicts that two distinct biological cycles modulate the visual response: a short cycle (~28 days, pupillary) and a long cycle (~365 days, macular). Three experimentally verifiable predictions derive directly from this model. This protocol describes the study design required to test these predictions using instrumentation already in routine clinical use. Objectives: To determine whether (1) individuals with larger angle kappa show greater amplitude of circadian pupillary oscillation; (2) foveal chromatic discrimination threshold covaries with longitudinal measurements of angle kappa over 12 months; and (3) the asymmetry between pupillary response in the first and second half of a 28-day cycle is proportional to individual angle kappa amplitude. Design: Longitudinal observational study. Setting: Any ophthalmic clinic equipped with infrared pupillometry and optical biometry. Participants: Healthy adult volunteers (18–50 years), n = 30 minimum per group. Interventions: Standardized pupillometric measurements (infrared pupillometry) combined with optical biometric measurements (IOLMaster 700 or equivalent) at scheduled intervals over 12 months. Primary outcome measures: Pupillary diameter under standardized photopic conditions; angle kappa (X and Y components); foveal chromatic discrimination threshold.
Succi et al. (Fri,) studied this question.