MRI study of the changes in crystalline lens shape with accommodation and aging in humans (original) (raw)
Related papers
ARVO
PURPOSE. To evaluate the effect of age and accommodation on lens cross-sectional area (CSA). METHODS. High-resolution magnetic resonance images of the eye were acquired from 25 subjects ranging in age from 22 to 50 years during accommodation and with accommodation at rest. The images were analyzed to obtain the total lens CSA and the CSAs of the anterior and posterior portions of the lens. RESULTS. The total lens CSA and the CSA of the anterior portion increased with age in both accommodative states. With accommodation, the CSA was larger in these portions of the lens; however, this difference decreased with age. Conversely, the CSA of the posterior portion of the lens remained statistically independent of both age and accommodative state. CONCLUSIONS. This preliminary study documents, in vivo, that the lens grows with age. This growth appears to be confined to the anterior portion. A quite unexpected finding is that both the total lens CSA and the CSA of the anterior portion are greater during accommodation when zonular tension is minimized. This accommodative change in CSA, which decreases with age, may be due to compression of the lens material during relaxed accommodation when zonular tension is greatest. That both age and accommodative changes in CSA appear to be limited to the anterior portion of the lens may be related to properties of the anterior capsule and lens material, the position of the zonular attachments, and the location of the fetal nucleus.
Changes in Lens Thickness and Amplitude of Accommodation with Age
International Journal of Anatomy Radiology and Surgery, 2020
Introduction: The human crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina and, by changing shape, it adjusts focal distance and this function of the lens is called accommodation. Accommodation is the way, the eye increases optical power as it is necessary to produce a clear image of an object when it draws near the eye. Ageing reduces the ability of the lens to change shape, to adjust for close or distance vision. Aim: To study the changes of lens thickness and Amplitude of Accommodation (AA) with age. Materials and Methods: In this cross-sectional study, 40 healthy females were recruited from September to December 2018. The right eyes of 40 healthy participants were divided into two groups, the group 1 of 20 younger subjects (age range 18 to 28 years, mean age 21.9±2.73 years), and group 2 of middleaged 20 subjects (age range 40 to 50 years, mean age 44.6±3.95 years). The lens thickness a...
Change in shape of the aging human crystalline lens with accommodation
Vision Research, 2005
The objective was to measure the change in shape of the aging human crystalline eye lens in vivo during accommodation. Scheimpflug images were made of 65 subjects between 16 and 51 years of age, who were able to accommodate at least 1 D. The Scheimpflug images were corrected for distortion due to the geometry of the camera and the refraction of the cornea and anterior lens surface, which is necessary to determine the real shape of the lens. To ensure accurate correction for the refraction of the anterior lens surface, the refractive index of the crystalline lens must be determined. Therefore, axial length was also measured, which made it possible to calculate the equivalent refractive index of the lens and possible changes in this index during accommodation.
British Journal of Ophthalmology, 2006
To understand the effect of the geometric and material properties of the lens on the age-related decline in accommodative amplitude. Methods: Using a non-linear finite-element model, a parametric assessment was carried out to determine the effect of stiffness of the cortex, nucleus, capsule and zonules, and that of thickness of the capsule and lens, on the change in central optical power (COP) associated with zonular traction. Convergence was required for all solutions. Results: Increasing either capsular stiffness or capsular thickness was associated with an increase in the change in COP for any specific amount of zonular traction. Weakening the attachment between the capsule and its underlying cortex increased the magnitude of the change in COP. When the hardness of the total lens stroma, cortex or nucleus was increased, there was a reduction in the amount of change in COP associated with a fixed amount of zonular traction. Conclusions: Increasing lens hardness reduces accommodative amplitude; however, as hardness of the lens does not occur until after the fourth decade of life, the age-related decline in accommodative amplitude must be due to another mechanism. One explanation is a progressive decline in the magnitude of the maximum force exerted by the zonules with ageing.
Aging of the human crystalline lens and anterior segment
Vision Research, 1994
Changes in the unaccommodated human crystalline lens were characterized as a function of subject age for 100 normal emmetropes over the age range H-70 yr by Scheimpflug slit-lamp photography. With increasing age, the lens becomes thicker sagittally, but since the distance from the cornea to the posterior lens surface remains unchanged, this indicates that the center of lens mass moves anteriorly and the anterior chamber becomes shallower. Sagittal nuclear thickness is independent of age, but both anterior and posterior cortical thicknesses increase with age, shifting the location of the nucleus and the central sulcus in the anterior direction. The amount of light scattered by the lens at high angles, as represented by normalized and integrated lens densities from the digitized images, increases with increasing age in an exponential fashion. Similar relationships to age are observed for the major anterior zone of discontinuity (maximum density) and the central sulcus (minimum density). The relationships of these results to accommodation and presbyopia are discussed. Accommodation Aging Anterior chamber Presbyopia Slit-lamp Scheimpflug photography Image processing
Change in the accommodative force on the lens of the human eye with age
Vision Research, 2008
The aim of the study was to determine the age-dependence of the accommodative force on the lens in order to make it clear whether the causes of presbyopia are due to lenticular or extralenticular changes. A finite element model of the lens of an 11-, 29-and 45-year-old human eye was constructed to represent the fully accommodated state. Subsequently, the force that was needed to mould the lens into its unaccommodated state was calculated. The force on the lens appeared to be preserved with age, with only a slight increase to a value of approximately 0.06 N. In conclusion, the preservation of the net force delivered by the extralenticular ciliary body indicates that the causes of presbyopia must be ascribed to lenticular changes.
Changes in the internal structure of the human crystalline lens with age and accommodation
Vision Research, 2003
Scheimpflug images were made of the unaccommodated and accommodated right eye of 102 subjects ranging in age between 16 and 65 years. In contrast with earlier Scheimpflug studies, the images were corrected for distortion due to the geometry of the Scheimpflug camera and the refraction of the cornea and the lens itself. The different nuclear and cortical layers of the human crystalline lens were determined using densitometry and it was investigated how the thickness of these layers change with age and accommodation. The results show that, with age, the increase in thickness of the cortex is approximately 7 times greater than that of the nucleus. The increase in thickness of the anterior cortex was found to be 1.5 times greater than that of the posterior cortex. It was also found that specific parts of the cortex, known as C1 and C3, showed no significant change in thickness with age, and that the thickening of the cortex is entirely due to the increase in thickness of the C2 zone. With age, the distance between the sulcus (centre of the nucleus) and the cornea does not change. With accommodation, the nucleus becomes thicker, but the thickness of the cortex remains constant.
Biometric changes of the crystalline lens during accommodation
Spektrum der Augenheilkunde, 2020
Background To measure intralenticular biometrical changes during accommodation. Material and methods This prospective study included two different age groups of volunteers (18-25 years and 30-39 years) and in each age group three different groups of ametropia (emmetropic, myopic, and hyperopic volunteers). All volunteers were measured using partial coherence interferometry (ACMaster, Carl Zeiss Meditec, Germany) in an unaccommodated and an accommodated state. Intralenticular biometric changes concerning anterior and posterior cortex and lens nucleus were analysed. Results In total, 104 eyes of 104 volunteers were included in this study. During accommodation in the group of subjects in their 20s, the following changes were observed: In the emmetropic group, the nucleus thickness increased by +0.414 mm, whereas the anterior cortex and posterior cortex thickness remained relatively constant at-0.006 mm (-0.186 mm to 0.046 mm) and +0.008 mm (-0.008 mm to 0.024 mm), respectively. Conclusions The increase of the human crystalline lens with age is characterised by a higher increase in cortex thickness than in nucleus thickness. During accommodation, the thickening of the lens is primarily explained by the thickening of the lens nucleus.