PROCESS FOR THE PRESERVATION AND CLEANING OF HYDROPHILIC LENSES

Abstract: Process for the preservation and cleaning of hydrophilic lenses comprising the hydrophilic lens freezing in a sodium chloride hypertonic solution or another substance that modifies the solution cryoscopic degree. The sodium chloride solution is used in a concentration of about 5% to 0.095% and in a temperature band of 0<o>C to -4<o>C.

Description: PROCESS FOR THE PRESERVATION AND CLEANING OF HYDROPHILIC LENSES Technical Field This invention relates to the preservation and cleaning of lenses in general and, more particularly to a process for the preservation and cleaning of hydrophilic lenses by means of the freezing in hypertonic solution of sodium chloride or another substance that modifies the cryoscopic solution degree. Background of the Invention As known in the field with which the present inven¬ tion is related to, one of the topics of greatest contro¬ versy in contactology is xindoubtedly the theme related to the preservation of hydrophilic lenses. As known, there are two available processes for the treatment of hydrophilic lenses, i. e., the chemical and the thermal. Asepsis and preservation chemical process uses basically thi erosalt and, as a preservative, the chloro- xedine. The advantages relative to this process are re¬ lated to its efficiency as an antisseptic and to its hand¬ ling facility. The high cost of the products, however, the development of hypersensitiveness processes with con¬ sequent intolerance to the use of lenses and the greatest facility of inorganic impregnation with, for instance, mercury and calcium salts, arise as negative factors limit ing its utilization. Three different stages may be outstanding in this process, thus included: lenses cleaning after use, with an available product, for example, PLIAGEL; preservation with products based on thimerosalt and chloroxedine; dis- proteinization periodically, with the purpose of making the proteins lysine, having as active agent, the papain. Among the three stages, the disproteinization may be con¬ sidered the one that presents the best results, inside what it proposes. However, the thermic process is constituted by two different technics, which are: The hot (by boiling) and the cold (by freezing) . The preservation process by heat is the most used and consists on the direct boiling or in water-bath, in a saline solution or distilled water. Apparently, boiling only presents the advantage of making calcium salts, in the form of carbonate, more soluble, which make difficult its impregnation and difficultates lipids deposition. This process, however, sins by the great risk of damn made to the lenses when realized under direct boiling in a common oven, what does not occur with electric aseptizers. Boiling also promotes the protein cooking, making them more agglutinated and adherent to the villosities of lens surface. We may cite as an example the phenomenon occur¬ ring with the white of the egg, basically constituted by albumine, a protein that predominates in the human tear, which on being subjected to cooking, gets firm and opaque, therefore different enough from its initial state. In the case of lenses, proteins also have these transformations and are therefore much more adherent and difficult to be removed when exposed to disproteinization. Boiling also promotes the shortening of the average lenses life, so as to increment polymeric instability. Disclosure of the Invention The present ' invention has the object of solving these problems providing a process for the preservation of hydrophilic lenses by freezing cold, a process that is simple, of low operational cost and developping no toxity at all. Taking into consideration the problems found out with the precedent processes, the inventor of the present process discovered that on submitting hydrophilic lenses to freezing, the latter presented neatly cleaner, what has been demonstrated and proved in a practical and theo¬ retical form. Exhaustive studies and tests have demonstrated that hydrophilic lenses subjected to the process of this invention allow, not only to diminish the secretion, but to increment also in a sensible way, the usuary comfort, of lenses subjected to the freezing process. Another advantage, verified in the use of this process is that the risk of damage, compared to the preceding processes, is equal to zero, since the lenses support freezing for an indefinite time. Another advantageous aspect of the process in the present invention is that the toxity is null, since we only use a sodium chloride solution in a conventration which is about 5,0% to 0,09% or another substance that modifies the solution cryoscopic degree, preferently without the pre¬ servatives. The operational cost is also practically null since the lenses freezing is obtained through a convention al house refrigerator. The following are some physical and chemical as- pects of the process advantages according to this inven¬ tion. Description of the Preferred Embodiment As known, the fat depositions ar those which impreg_ nate more rapidly the hydrophilic lenses surface. Some experiments have demonstrated that after 30 minutes use, 50% of the lenses area are already involved with fat depositions. On submitting lenses to freezing, it was verified that these depositions are taken away owing to the fat agglutination mechanism. The most common example which may be offered, in an illustrative sense, is that observed when we put a fat food into a refrigerator. As the food is heated or hot, fat takes away and gets more fluid, spreading all over the container surface where it ~ is. As food is put inte the refrigerator, it is verified that after some time the fat of that food condensates in a uniform way and in a same level. This is exactly the phenomenon ocurring on the lenses, by the fact that fats agglutinate at a molecular level at the moment they are refrigerated, as a great puzzle was mounted. On the other hand, as that fat is heated, the molecular interaction force is undone, as the puzzle were dismounted. Once the agglutination phenomenon occurred, it was decided to research the reason why this material was taken away and this stage was classified as a "unglueing phenom¬ enon", coming to the following conclusion: Considering that hydrophilic lenses present a structure somewhat similar to the sponges - in the passage from liquid to solid state, it is observed that: 1 ) gelatinous material contracts itself, i. e. , it diminishes its volume; 2) liquid contained in gelatinous material expands itself? once the liquid volume is larger than hidrogel volume, its expulsion occurs, carrying along with it all the compo¬ nents spread on lens surface. For this reason, the or¬ ganic depositions find it difficult to fix on lenses treated by means of process of the present invention. For inorganic depositions , principally calcium salts, pumping mechanism by contraction to cold, also ma¬ kes its impregnation difficult. The contamination by fungi and bacteria becomes significantly lower. As bacteria depend on the deposition of mucus to develop themselves and also by the very action of cold, they do not contrive do adhere the lenses surface. Finally, polymeric stability of hydrophilic lenses, subjected to the process of the invention is superior to that of lenses subjected to the other conventional proces¬ ses of preservation, what enlarges hydrophilic lenses over life.

Claims: CLAIM 1 - Process for the preservation and cleaning of hydrophilic lenses, comprising the lens freezing in a hypertonic solution of sodium chloride os another sub¬ stance able to modify the solution cryoscopic degree, used in a concentration of about 5% to 0,09% and where said solution passes from liquid to solid state in a band of 0°C to -4°C for the expulsion of all the components spread on the lens surface.

Inventors: CAPELLA ANTONIO PIRES, GRYNER DAVID, RIBEIRO ANTONIO CARLOS HALLAIS, CAPELLA, ANTONIO, PIRES, GRYNER, DAVID, RIBEIRO, ANTONIO, CARLOS, HALLAIS
Applicants: CAPELLA ANTONIO PIRES, GRYNER DAVID, RIBEIRO ANTONIO CARLOS HALLAIS, CAPELLA, ANTONIO, PIRES, GRYNER, DAVID, RIBEIRO, ANTONIO, CARLOS, HALLAIS
Application year: 1985
Main classification: B08B3
IPC codes: A61L12, B08B3, G02C7, G02C13