Artigas Felipe, Cristina

Purpose: The porcine eye is frequently used as a research model. This paper analyzes the effect of different storage methods on the transparency of pig crystalline lens. Methods: A spectral transmission curve (from 220 to 780 nm) for the crystalline lens was determined experimentally after storage in different conditions: saline solution, formalin, castor oil, and freezing at -80°C. The total transmission in the visible spectrum, which was used as an index of transparency, was calculated from these curves. For comparative purposes, fresh lenses were evaluated and used as controls. Results: Storing the porcine crystalline lens in saline solution or castor oil resulted in a transparency loss of approximately 10% after 24 h and storage in formalin resulted in a loss of nearly 30%. Storage by freezing at -80°C for 4 weeks maintained the transparency of the crystalline lens; the spectral transmission measured immediately after defrosting at room temperature coincided exactly with that of the freshly extracted lens. Conclusions: The transparency of porcine crystalline lens is affected by the storage method. The visible spectrum is the most affected, evidenced by the effect on the transparency and consequently the amount of light transmitted. The results show that freezing at -80°C maintains the transparency of the crystalline lens for at least 4 weeks.

La radiación ultravioleta (UV) es uno de los factores más influyentes en la formación de opacidades en el cristalino tanto en humanos como en animales. El efecto de la radiación sobre un ser vivo depende de tres factores: el tipo de radiación, su intensidad y el tiempo de exposición. En la bibliografía existen estudios tanto in vivo como in vitro realizados en diferentes especies que tratan el efecto de la radiación UV en el cristalino, pero ninguno en la lente intacta de cerdo in vitro. El cerdo es un animal que desde hace 20 años ha empezado a considerarse en investigación oftalmológica debido a su similitud filogenética con el ser humano. En nuestro estudio hemos dispuesto de 75 cristalinos de cerdo y se realizaron diferentes experimentos. Como principal estudio, se expusieron algunos cristalinos a radiaciones UVA y UVB a diferentes intensidades (10 y 20 J/cm2) y tiempos entre 0 y 30 minutos, para estudiar sus efectos en la transmisión espectral. Además, se hicieron otros experimentos paralelos: se estudiaron distintos métodos de conservación de la lente explantada, se estableció la curva de transmisión espectral del cristalino de cerdo, y se hizo un estudio preliminar sobre la regeneración del cristalino tras la irradiación con radiación ultravioleta. Los resultados mostraron que cuando se irradia el cristalino con radiación UV, el daño producido en la lente es directamente proporcional a la intensidad y el tiempo, es decir, cuanta más intensidad más daño; y con una misma intensidad, cuanto más se prolonga la radiación más lesiones produce en la lente. También se comprobó que la radiación UVB es más dañina que la UVA, y por tanto necesita menos intensidad para producir el mismo daño. Por otra parte, la curva de transmisión del cristalino de cerdo, deja pasar todo el espectro visible y aproximadamente un 15% del UV. Por otro lado, la transmisión del cristalino de cerdo no sufre variaciones significativas en una hora tras su extracción del ojo enucleado. El método de conservación que mejor preserva la transmisión del cristalino es la criocongelación a -80º. Finalmente, se observó una ligera recuperación de la transmisión del cristalino tras hora y media de su exposición a radiación UVA, y sólo tras media hora en el caso de UVB, donde después la curva volvió a disminuir. UV radiation is one of the most influential factors affecting the formation of opacities in the crystalline, both in humans and animals. The effect of radiation on a living organism depends on three factors: type of radiation, intensity and time of exposition. Previous work in literature shows studies both in vivo and in vitro of the effect of UV radiation on different species, but none of them study the effect on an intact lens of a pig. A pig is an animal that since now 20 years has been considered for ophthalmological research due to the phylogenetic similarities with humans. In our study, we have disposed of 75 crystallines of pigs for several experiments. In the main experiment, the crystalline of the pig was exposed to UVA and UVB radiation at different intensities (10 y 20 J/cm2) and exposure times ranging 0 to 30 minutes. The goal of these experiments is to observe the influence of UV radiation on the spectral transmittance of the lens. In parallel, several other factors were studied that we thought could be influential to the results of the work. Some preservation methods of the extracted lens were studied to observe if they would modify the spectral transmission. Additionally, the spectral transmission curve for the pig lens was established and compared with the human lens. Finally, a preliminary study of the crystalline regeneration after UV irradiation was performed. Results indicate that when the crystalline is irradiated with UV light, the damage caused on the lens is directly proportional to the intensity and the time of exposition. As the intensity or the time of exposition increases the damage increases. UVB is more harmful for the crystalline than UVA, as it was observed that less intensity is needed to produce the same damage. The spectral transmittance curve of the pig shows that all visible spectrum is transmitted and also around 15% of UV radiation. Moreover, the transmittance of the crystalline suffers no significant variations after an hour of its explantation without the need of any preservation method. If longer times are needed, the best method of preservation of the spectral transmission of the lens is cryo-freezing at -80ºC. The study showed a light regeneration of the transmission of the lens one hour and a half after exposure to UVA radiation, and only 30 minutes after UVB.