Optical Power and Diameter of In Situ versus Isolated Primate Crystalline Lenses Ex Vivo

Abstract

 

Purpose:

 

To determine if the tension on the cadaver crystalline lens changes when the lens is isolated from its supporting framework.

 

Methods:

 

Four whole pre-presbyopic human (average 32.2±6.6 years, range 26-44 years, <5 days postmortem) and twenty-four cynomolgus monkey (average 6.2±2.1 years, range 4-9 years, <1 day postmortem) eyes were carefully dissected leaving the lens, zonules, ciliary body, hyaloid membrane and anterior vitreous intact. The shape of the intact globe was preserved by bonding a fixed matching ring to the scleral surface. The lenses maintained in their supporting framework were immersed in a cell filled with DMEM at room temperature. Optical power was measured using a custom designed Badal-type lensometer and the equatorial diameter was measured at 20X magnification on undistorted shadowphotographs. The lenses were then excised by cutting the zonules with Vannas scissors and immediately re-immersed in DMEM at room temperature. Optical power and equatorial diameter measurements were then repeated on the isolated lenses. Visibly swollen or delaminated lenses in the shadowgraph images were excluded.

 

Results:

 

While only statistically significant in the monkey (p=0.0063), for both species, there was an apparent decrease in the diameter and increase in the power when the lens was removed from its supporting framework (see Table).

 

Conclusions:

 

The results suggest that the in situ cadaver lens is under residual tension.  

 

Keywords: optical properties