The lens power decreases with age, due mainly to a decrease in the contribution of the gradient. The use of a constant equivalent refractive index value to calculate lens power with the lens maker formula will underestimate the power of young lenses and overestimate the power of older lenses.

Purpose To develop an age-dependent mathematical model of the isolated ex-vivo human crystalline lens shape to serve as basis for use in computational modeling. Methods Profiles of whole isolated human lenses (n=27) aged 6 to 82, were measured from shadow-photogrammetric images. Two methods were used to analyze the lenses. In the Two-Curves Method (TCM) the anterior and posterior surfaces of the lens were fit to 10th-order even polynomials and in the One-Curve Method (OCM) the contour of one half-meridional section of the lens was fit to 10th-order polynomials. The age-dependence of the polynomial coefficients was assessed. The analysis was used to produce an age-dependent polynomial model of the whole lens shape. Results The root mean squared errors for the fits ranged from 11 to 70 μm for the OCM, 9 to 27 μm for the posterior surface of the TCM and 8 to 134 μm for the anterior surface of the TCM. The coefficients of the OCM did not display a significant trend with age. The 2nd, 6th and 10th-order coefficients of the anterior surface of the TCM decreased with age while the 8th-order coefficient increased. For the posterior surface of the TCM, the 8th-order coefficient significantly decreased with age and the 10th-order coefficient increased. The age-dependent equations of both the models provide a reliable model from age 20 to 60. The OCM model can be used for lenses older than 60 as well. Conclusion The shape of the whole human crystalline lens can be accurately modeled with 10th-order polynomial functions. These models can serve to improve computational modeling, such as finite element (FE) modeling of crystalline lenses.

PURPOSE.To quantify the role of anterior zonular tension on the optomechanical lens response during simulation of accommodation in primates. METHODS. Postmortem cynomolgus monkey eyes (n ϭ 14; age range, 3.0 -11.5 years) were dissected leaving intact the lens, zonules, ciliary body, hyaloid membrane, anterior vitreous, and a scleral rim. The lens was mounted in a lens-stretching system and stretched radially in step-wise fashion. The load, and the lens diameter and power were measured at each step and the diameter-and power-load relationships were quantified. The anterior zonular fibers were then transected, and the experiment was repeated. The equatorial lens diameter and lens optical power before and after zonular transection were compared. RESULTS. Stretching increased the lens diameter by 0.25 Ϯ 0.09 mm (median Ϯ interquartile range) before and 0.25 Ϯ 0.19 mm after zonular transection. Stretching decreased the lens power by 13.0 Ϯ 6.5 D before and 10.6 Ϯ 8.0 D after zonular transection. The load required to change the diameter of the lens by 1 mm decreased from 18.8 Ϯ 10.7 g before to 15.0 Ϯ 7.8 g after zonular transection. The absolute change in power per gram of loading decreased from 2.5 Ϯ 1.1 before to 2.0 Ϯ 1.2 D after zonular transection. CONCLUSIONS.The cynomolgus monkey lens retains a significant fraction of its accommodative ability after transection of the anterior zonules in simulated accommodation experiments.

Laser trabeculoplasty (LT) is a commonly used modality of treatment for glaucoma. The mechanism by which LT lowers the intraocular pressure (IOP) is unknown. Using cat eyes, selective laser trabeculoplasty (SLT) with a Q-switched frequency doubled Nd:YAG laser was used to treat the trabecular meshwork (TM). Laser treated TM was then subjected to proteomic analysis for detection of molecular changes and histological analysis for the detection of structural and protein expression patterns. In addition, the protein glycosylation patterns of laser treated and non-treated TM was assessed and differentially glycosylated proteins were proteomically identified. SLT laser treatment to the TM resulted in elevated glycosylation levels compared to non-lasered TM. TM laser treatment also resulted in protein expression levels changes of several proteins. Elevated levels of biglycan, keratocan and prolargin were detected in laser treated TM compared to non-lasered controls. Further investigation is anticipated to provide insight into how glycosylation changes affect TM proteins and TM regulation of aqueous outflow in response to laser trabeculoplasty.