The optical properties of rat, porcine and human lenses in organ culture treated with dexamethasone

Abstract

Organ culturing of lenses is useful for testing the direct effect of moieties such as cations, glucose, oxygen, antioxidants or drugs on the lens. Lens opacity changes in organ cultured lenses have never been measured quantitatively. Our aims were twofold: to establish the time course of lens opacity changes in organ cultured rat, porcine and human lenses and to test the utility of our system to measure opacity changes in lenses treated with dexamethasone. Human, porcine and rat lenses were incubated with or without 5 μM dexamethasone in minimum essential medium for 13 days. Lens absorbance and light scattering were measured using a spectrometer. Lens opacity was graded from lens photographs. Sixteen human lenses were obtained from 10 donors. Light scattering accounted for all of the absorbance of the human lens above 550 nm, 72% of the absorbance at 500 nm and 50% of the absorbance at 450 nm. Similarly, for the porcine lens, light scattering accounted for all of the absorbance above 400 nm and 40% of the absorbance at 350 nm. For the rat lens, scattering accounted for all of the absorbance above 325 nm, and 37% of the absorbance at 300 nm. In the rat lens spectrum, the broad absorbance peak near 600 nm was unique to the rat lens. After day five in organ culture, the level of light scattering, absorbance and optical grade of human lenses were higher in dexamethasone treated lenses compared with those without dexamethasone. Similar differences were observed for rat lenses after one day in organ culture. The opacity of porcine lenses did not change with dexamethasone treatment. In conclusion, this study showed that dexamethasone-induced opacity in human and rat lenses could be measured which is important to future studies to test the positive or negative efficacy of moieties that cause or ameliorate cataract.