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.
Study Type
OBSERVATIONAL
Enrollment
120
Second Affiliated Hospital, Zhejiang University School of Medicine
Hangzhou, Zhejiang, China
NOT_YET_RECRUITINGSecond Affiliated Hospital, Zhejiang University School of Medicine
Hangzhou, Zhejiang, China
RECRUITINGCentral corneal thickness changes during accommodation
Central corneal thickness CCT(μm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
peripheral corneal thickness changes during accommodation
peripheral corneal thickness(μm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
anterior chamber depth changes during accommodation
anterior chamber depth ACD(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
anterior chamber Angle Angle changes during accommodation
anterior chamber Angle Angle ACA(°)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
anterior opening distance changes during accommodation
anterior opening distance AOD(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
pupil size changes during accommodation
pupil size PD(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
lens thickness changes during accommodation
lens thickness LT(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
anterior and posterior surface curvature radius changes during accommodation
anterior and posterior surface curvature radius(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
lens arch height changes during accommodation
lens arch height LV(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
lens sagittal height changes during accommodation
lens sagittal height(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
anterior chamber volume changes during accommodation
anterior chamber volume(mm³)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
posterior chamber volume changes during accommodation
posterior chamber volume(mm³)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
crystal equatorial diameter changes during accommodation
crystal equatorial diameter(mm)
Time frame: Baseline, after accommodation(30 minutes after using pilocarpine)
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