Accommodation is defined as a dynamic change in the overall refractive power of the eye during near fixation. Despite extensive investigations, the exact nature of human accommodation remains controversial. And recent alternative theories question the original concept of accommodation.Different experts have put forward different hypotheses. The age-related changes that underlie presbyopia are also not fully understood.Because of these unanswered questions, the topic of regulation and presbyopia remains a focus of research.

Accommodation is the process by which the eye changes the shape and diopter of the lens to obtain a clear image of an object at different distances. Despite extensive research on regulation, the exact nature of human regulation remains controversial. Age-related changes in presbyopia are also not fully understood. Some studies have shown that a hardening of the lens and an increase in the thickness and diameter of the lens with age can lead to presbyopia. Others believe that the main cause is external lens factors, such as age-related changes in the Angle of lens suspension ligament attachment, reduced ciliary body movement, etc. Due to these unanswered questions, the topic of regulation and presbyopia remains the focus of research. In living humans, modulation studies utilize different imaging modes, and ultrasound biomicroscopy (UBM) and Optical Coherence Tomography(OCT) are particularly important in studying anterior segments and modulation. However, UBM is a contact inspection and requires highly skilled technicians. And UBM cannot image the entire anterior segment in a single capture. Anterior segment OCT (AS-OCT), on the other hand, is non-invasive and provides higher resolution imaging, allowing us to capture the morphology of the anterior segment structures in different populations and the changes of the anterior segment structures in response to regulatory stimuli. Studies have shown that with age, reduced anterior chamber depth, pupil contraction, increased lens thickness, increased lens arch height, and loss of posterior ciliary muscle contraction may be biomarkers of early presbyopia. In this study, anterior segment OCT was used to explore whether there were differences in the structural morphology of the anterior segment in people of different ages, and what changes occurred in the structure of the anterior segment after initiation of regulation.

Inclusion Criteria:

· Patients with astigmatism ≤-1.50D and best corrected visual acuity ≥4.9

Exclusion Criteria:

• Patients with other systemic diseases
• Patients with a history of eye surgery
• Patients with intraocular lens or aphakia
• Patients with strabismus and amblyopia
• Pregnant or lactating women
• People with mental disorders or neurological diseases who cannot cooperate with the examination

Age 20-80 years old; Astigmatism ≤-1.50D; Best corrected visual acuity ≥4.9;Excluding other systemic underlying diseases; Have a history of eye surgery; Patients with intraocular lens or aphakia; Patients with strabismus and amblyopia; Pregnant or lactating women; People with mental disorders or neurological diseases who cannot cooperate with the examination;