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PURPOSE-To quantify in vivo accommodative changes in the aging human ciliary muscle diameter in phakic and pseudophakic eyes. METHODS-Images were acquired from 48 eyes of 40 people between the ages of 22 and 91 years, 1 eye of 32 phakic volunteers and both eyes of 8 patients who had monocular implantation of a single-piece AcrySof intraocular lens (IOL) (Alcon Laboratories). Images were acquired during physiological accommodation and with accommodation at rest, and the diameter of the ciliary muscle ring was measured. SETTING-Department RESULTS-Resultsshow the ciliary muscle remains active throughout life. The accommodative change in its diameter (mean 0.64 mm) (P<.00001) was undiminished by age or IOL implantation. Preliminary data showed that the accommodative decrease in muscle diameter in phakic and pseudophakic eyes was statistically identical. The phakic eyes had a marked decrease in ciliary muscle diameter with advancing age for both accommodative states (P<.000001 and P<.000001), which did not appear to be altered by IOL implantation. The lens equator was constant with age in the unaccommodated human eye, resulting in decreased circumlental space with advancing age in the phakic eyes.CONCLUSION-Although the undiminished ability of the ciliary muscle to decrease its diameter with accommodation can be relied on in strategies for presbyopia correction, even in advanced presbyopia, the decreasing circumlental space and its potential effects on zonular tension must also be considered.New strategies, including lens softening, lens refilling, scleral expansion, and potentially accommodating intraocular lenses (IOLs), are being developed to restore accommodation in presbyopic eyes. 1-11 Because a functioning ciliary muscle is key to each procedure or device, it is increasingly important to quantify in vivo accommodative changes in the aging ciliary muscle of phakic and pseudophakic eyes. Although the iris obscures direct observation of the ciliary muscle in the normal, intact human eye, magnetic resonance This ability to observe the geometric relationship of the accommodative structures with MRI has also provided the only statistically significant demonstration that the Helmholtz theory 24 of human accommodation is correct. Strenk et al. 21 found that in response to an accommodative stimulus, a decrease in the ciliary muscle ring diameter and the lens equatorial diameter occurred, with a corresponding increase in lens thickness. Although the lenticular changes decreased with advancing age, the accommodative change in the ciliary muscle ring diameter was undiminished throughout life, with a mean value of 0.661 mm. A possible trend toward a slight decrease in muscle contraction with advancing age was present but not statistically significant. However, only a limited number of people with advanced presbyopia were enrolled. The mean age of the 25 subjects in the study was 39.10 years (range 22 to 83 years). Only 1 subject was older than 62 years. Here, we expand the age range to 91 years and provide a more u...

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.

High-resolution imaging with a camera system built on the Scheimpflug principle has been used to characterize the geometry of the anterior segment of the adult human eye as a function of aging and accommodative state but is critically dependent on algorithms for correction of distortion. High-resolution magnetic resonance imaging (MRI), in contrast, provides lower-resolution information about the adult eye but is undistorted. To test the accuracy of the Scheimpflug correction methods used by Cook and Koretz [J. Opt. Soc. Am. A 15, 1473 (1998)]; [Appl. Opt. 30, 2088 (1991)], data on anterior chamber and segment lengths, as well as lens thickness and anterior and posterior curvatures, were compared with corresponding MRI data for adults aged 18-50 at 0 diopter accommodation. Excellent statistical agreement was found between the MRI and the Scheimpflug data sets with the exception of the posterior lens radius of curvature, which is less well defined than the other measurements in the Scheimpflug images. The considerable agreement between data obtained with MR and Scheimpflug imaging, two different yet complementary in vivo imaging techniques, validates the Scheimpflug correction algorithms of Cook and Koretz and suggests the capability of directly integrating information from both. A third, equivalent, data set obtained with a Scheimpflug-style camera system differs considerably from both Scheimpflug and MRI results in magnitude and age dependence, with negative implications for this alternative method and its correction procedures.

PURPOSE To quantify accommodative and age-related changes in the anteroposterior position and thickness of the ciliary muscle in phakic and pseudophakic eyes. SETTING Department of Surgery/Bioengineering, UMDNJ–Robert Wood Johnson Medical School, Piscataway; Institute of Ophthalmology and Visual Science UMDNJ–New Jersey Medical School, Newark, New Jersey; MRI Research, Inc., Middleburg Heights, Ohio, USA. METHODS Magnetic resonance images were taken of phakic and pseudophakic eyes. RESULTS The cohort comprised 32 phakic volunteers and 8 volunteers with a monocular intraocular lens (IOL) aged 22 to 91 years. No anteroposterior accommodative movement of the ciliary muscle apex occurred in either group. The muscle moved closer to the cornea with advancing age in phakic eyes; IOL implantation returned the muscle to a youthful position. An age-dependent increase in ciliary muscle anteroposterior thickness occurred that was not mitigated by IOL implantation. Muscle thickness increased with accommodation only in phakic eyes. CONCLUSIONS Presbyopia-correction strategies cannot rely on accommodative anterior movement of the ciliary muscle. Forces on the uvea by crystalline lens–pupillary margin contact may increase with accommodation and lens growth, producing accommodative and age-dependent increases in muscle thickness and significant age-dependent anterior muscle displacement. Intraocular lens implantation removed these forces, allowing choroidal elasticity to restore the muscle to a youthful position; however, the increase in thickness was permanent and likely due to an age-dependent increase in connective tissue. This supports the geometric theory of presbyopia development and that the mechanical forces in human accommodation and presbyopia are very different from those in the rhesus monkey model.