tion, mammalian lenses change shape from a rounder configuration (near focusing) to a flatter one (distance focusing). Thus the lens must have the capacity to change its volume, capsular surface area, or both. Because lens topology is similar to a torus, we developed an approach that allows volume determination from the lens cross-sectional area (CSA). The CSA was obtained from photographs taken perpendicularly to the lenticular anterior-posterior (A-P) axis and computed with software. We calculated the volume of isolated bovine lenses in conditions simulating accommodation by forcing shape changes with a custom-built stretching device in which the ciliary body-zonulae-lens complex (CB-Z-L) was placed. Two measurements were taken (CSA and center of mass) to calculate volume. Mechanically stretching the CB-Z-L increased the equatorial length and decreased the A-P length, CSA, and lens volume. The control parameters were restored when the lenses were stretched and relaxed in an aqueous physiological solution, but not when submerged in oil, a condition with which fluid leaves the lens and does not reenter. This suggests that changes in lens CSA previously observed in humans could have resulted from fluid movement out of the lens. Thus accommodation may involve changes not only in capsular surface but also in volume. Furthermore, we calculated theoretical volume changes during accommodation in models of human lenses using published structural parameters. In conclusion, we suggest that impediments to fluid flow between the aquaporin-rich lens fibers and the lens surface could contribute to the aging-related loss of accommodative power.lens volume calculation; intralenticular fluid movement; presbyopia; mammalian lens THE EYE IS ABLE TO FORM a clear image on the retina from objects situated within a wide range of distances due to a process called accommodation. In higher vertebrates, including humans, accommodation results from changes in crystalline lens shape and surface radii of curvature (13).When the ciliary muscle is relaxed and flattened against the sclera, the zonulae adjoining the ciliary body and the lens capsule are under tension and thus pulling eccentrically on the lens equator. This action causes the lens to adopt a relatively flattened shape with a larger equatorial diameter and a shorter A-P length, which allows focusing on virtual infinity (zero accommodation). When an individual focuses on a near object, the ciliary muscle contracts (shortening its distance to the lens equator), the zonulae relax, and the lens as a whole adopts a relatively rounded shape, which is its normal tendency. Physically, these changes in lens shape inevitably must involve changes in either capsular surface area or lens volume, or both.Classic theories of lenticular accommodation suggest that the volume of the intraocular crystalline lens remains constant during the accommodation process (16,17,30). No empirical studies have demonstrated that the volume actually stays constant. Because of the physical principle mentioned abov...

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Purpose: Clinical guidelines suggest that for low-grade, clinically localized prostate cancer, patients with higher volume of disease at diagnosis may benefit from definitive therapy, although the data remain unclear. Our objective was to determine associations between low-grade prostate cancer volume and outcomes in men managed with primary radical prostatectomy. Materials and Methods: Men with cT1-2N0/xM0/x prostate cancer, prostate specific antigen at diagnosis <10 ng/mL, and Gleason grade group 1 pathology on diagnostic biopsy managed with primary radical prostatectomy were included. Outcomes were pathological upgrade at radical prostatectomy (Gleason grade group 2), University of California, San Francisco adverse pathology at radical prostatectomy (Gleason grade group 3, pT3/4, or pN1), alternate adverse pathology at radical prostatectomy (Gleason grade group 3, pT3b, or pN1), and recurrence (biochemical failure with 2 prostate specific antigen 0.2 ng/mL or salvage treatment). Multivariable logistic regression models were used to estimate associations between percentage of positive cores and risk of upgrade and adverse pathology at radical prostatectomy. Multivariable Cox proportional hazards regression models were used to estimate associations between percentage of positive cores and hazard of recurrence after radical prostatectomy. Results: A total of 1,029 men met inclusion criteria. Multivariable logistic regression models demonstrated significant associations between percentage of positive cores and pathological upgrade (OR 1.31, 95% CI 1.1-1.57, P < .01), but not University of California, San Francisco adverse pathology at radical prostatectomy (P [ .84); percentage of positive cores was negatively associated with alternate adverse pathology (OR 0.67, 95% CI 0.48-0.93, P [ .02). Multivariable Cox regression models demonstrated no association between percentage of positive cores and hazard of recurrence after radical prostatectomy (P [ .11). Conclusions: In men with Gleason grade group 1 prostate cancer, tumor volume may be associated with upgrading at radical prostatectomy, but not more clinically significant outcomes of adverse pathology or recurrence.

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