refractive status and accommodation response under different experimental conditions.

Conditions: Accommodation Disorder; Accommodative Fatigue; Accommodative Inertia

Summary: eye care professionals (ecps) massively use auto-refractors during the patient journey to measure the objective refractive error: starting point of the subjective eye refraction. these devices provide objective information about the refractive and accommodative state of the eye, useful for the ecp to perform a complete eyesight test. auto-refractor data for the distance vision are repeatable and accurate but near vision information are not enough reliable to build an accurate near vision routine exam. previous internal studies, with auto refractors currently on the market, have shown that, during accommodation measurements, a large proportion of participants had a lower accommodative response than expected.

clinical development stage and rationale the clinical development stage is pilot stage as defined in iso 14155:2020 (annex i section 1.3.2).this clinical investigation is an exploratory clinical investigation as mentioned in the medical device regulation eu 745/2017, also named early feasibility clinical investigation in the iso 14155:2020. the necessity of such clinical investigations is more precisely described by the food and drug administration (fda) (attachment e cdrh final guidance cover sheet) and agence nationale de sécurité du médicament et des produits de santé (ansm), where they detail the importance of exploratory studies in pivotal investigation design. medical devices often undergo design improvement during development, with refinement during lifecycles beginning with early research, extending through investigational use and initial marketing of the approved or cleared product, and continuing to subsequently approved or cleared commercial device versions. objectives and hypotheses of the clinical investigation this clinical investigation explores new ways of measuring accommodative response, particularly regarding the dynamics and amplitude of response: we chose to vary several parameters.

Eligibility criteria:
inclusion criteria: * volunteer: man or woman from 18 to 40 years old, * subject declares that his last visit to an ophthalmologist was less than 12 months ago, * subjects without a reported pathology, deficit or disorder that can interfere with visual or cognitive functions, * subjects, healthy volunteers who have been fully informed of the investigation and signed the informed consent form of the investigation, * subjects available for the investigation visits (at least 2 hours), * subjects able to appoint a visit in the investigator's site, * subjects able to read and understand the protocol (in french), follow the instructions, and give their informed consent approval. exclusion criteria: * subjects with spherical equivalent wearing compensation (or fully compensate by contact lenses) ranging out from -3.00 to + 3.00 dioptres in both eyes, * subjects with an astigmatism wearing compensation (or fully compensate by contact lenses) more than 1.00 dioptres (\>1,00dc) in both eyes, * subjects with a best compensated monocular va \ 0.1logmar), * persons subject to a legal protection measure (guardianship, curatorship, safeguard of justice, etc.) or unable to express their consent (see article l 1121-8 of the csp) * persons deprived of their liberty by judicial or administrative decision and persons hospitalised without their consent (article l1121-6 of the csp), * subjects under exclusion period from another investigation, * women pregnant or breastfeeding; (article l1121-5), * subjects with a reported neurologic disorder, particularly epileptic or sensory motor troubles, * subjects with implanted electronic medical device such as (pacemaker or hearing aid), * subjects with a reported severe ocular disease leading to a visual field decrease, va deficiency or glare sensitivity, * subjects with monophtalmia * subjects who had ocular surgeries (including aphakia or pseudophakia (intraocular lenses), refractive surgery or trauma), * subjects who are essilor international employees * subjects who are not affiliated to a social security scheme or are beneficiaries of such a scheme (article l1121-8-1 of the csp). * subject with fixation disorder: impossibility to maintain fixation on visual target. * subjects who cannot stay comfortable during the tests (e.g. with neck pain ...). * pupil abnormality (unusual shape, size \<3mm)