Lens care solutions

Medical devices have to be registered. This category includes medical instrumentation, implants, radioactive substances for diagnostic purposes and contact lenses, including lens care solutions that come in contact with the eye. 

In flow-based analytical procedures where the chemical reactions involved and/or the steps of analyte separation/concentration are relatively slow, the analytical signal can be attenuated by reducing the mean available time for the development of these physico-chemical processes. From a practical point of view, the result is equivalent to in-line analyte dilution. This possibility has been exploited in the spectrophotometric determination of hydrogen peroxide in contact lens care solutions using a sequential injection lab-on-valve system [60]. In view of the high sensitivity of the reaction between the analyte and 2,2,-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) in the presence of the enzyme... 

Hydrogen peroxide Lens care solutions Dialysis UV-Vis Up to 342 mg L 1 Sequential injection lab-on-valve system low dialysis efficiency (1.25 %) to promote in-line dilution, thus sensitivity reduction enzymatic assay [60]... 

S.S.M.P. Vidigal, I.V. Toth, A.O.S.S. Rangel, Sequential injection lab-on-valve system for the on-line monitoring of hydrogen peroxide in lens care solutions, Microchem. J. 91 (2009) 197. 

Two kinds of soft hydrogel contact lenses were cleaned with different lens care solutions (ECS) and analyzed by XPS. The elemental composition did not vary strongly between the different systems but the 0=C/0—C concentration ratio varied by a factor of 5. It was inversely correlated with the initial deposition rate measured in adhesion tests of P. aeruginosa performed in a laminar flow chamber. This revealed the adverse effect of compounds rich in O-C moieties adsorbed from the LCS. " After the contact lenses were worn, the presence of nitrogen-rich compounds and a much higher O /O—C concentration ratio were observed. The initial deposition rate of bacteria was lower on worn than on unworn contact lenses. ... 

The commercialization of the first pharmaceutical quality lens care products occurred in the 1950s. Harry Hind, a pharmacist and founder of the Barnes-Hind Company, has been credited as one of the first to develop and commercialize a wetting and storage solution for the rigid PMMA plastic lenses. Prior to his efforts, the literature mentions formulation of a saline solution containing sodium bicarbonate to be used with scleral lenses made from glass. 

Rigid lens care also includes conditioning solutions to make the basic hydrophobic polymers wettable when placed on the eye. 

Marketed lens care products fall mainly into the following categories cleaners, disinfectants, lubricants, and multipurpose products. Cleaners are subdivided into daily or weekly cleaners. Disinfectants comprise solutions containing chemical antimicrobial agents, which do not require heating the lenses, and preserved or unpreserved saline solutions, which are used with an electrical thermal device for lens disinfection. These products are also used to rinse contact lenses. Lens lubricants are intended to enhance the comfort of lens wear and are used prior to insertion and during wear. Multipurpose solutions are intended to accomplish... 

Poloxamer 338 and 407 are used in solutions for contact lens care. See Table n. 

Write a set of instructions that could be included in a package of contact-lens cleaning solution containing an enzyme. This enzyme catalyzes the breakdown of protein residues that adhere to the lenses. Include information about the structure and function of enzymes and the care that must be taken to avoid their denaturation during use. 

Contact urticaria from papain has been reported by Baur et al. (1982) in papain workers, and from contact-lens cleansing solutions by Bernstein et al. (1984), Santucci et al. (1985) and Podmore and Storrs (1989). Papain persists in the soft lens matrix despite careful rinsing (Fichman et al. 1978). In a factory manufacturing papain, Baur et al. (1982) reported that 17 of 33 workers developed type-i reactions such as periorbital edema, conjunctival irritation or allergic asthma. 

Lens care product components have the potential to affect the physiological response and comfort of Si-Hy CLs. The most common cHnical presentation of the chemical interaction between CL solutions and the ocular surface is the so-called solution-induced corneal staining (SICS) that has been observed with Si-Hy CL, particularly when PHMB-preserved care solutions are used (Figure 19.6). It has been observed that Si-Hy materials when used with care systems containing... 

When the solution is just cold the crystals, previously le-moved, are sown evenly over the bottom of the dish at distances of I—2 cms. apart and left for two days. The crystals will have now grown to a size which will enable the facets to be readily recognised. Each crystal is dried and carefully examined with a pocket lens in order to determine the position of the hemi-hedral facets, and placed in separate heaps. These facets lie to the right or left hand of the central prism face, as shown in Fig. 74. The crystals should be weighed, dissolved, and the solution diluted and examined in the polarimeter. The specific rotation may then be calculated. See Appe7idix., p. 264. 

This preservative is comparatively new to ophthalmic preparations and is a polymeric quaternary ammonium germicide. Its advantage over other quaternary ammonium seems to be its inability to penetrate ocular tissues, especially the cornea. It has been used at concentrations of 0.001-0.01% in contact lens solutions as well as dry eye products. At clinically effective levels of preservative, POLYQUAD is approximately 10 times less toxic than benzalkonium chloride [87,137], Various in vitro tests and in vivo evaluations substantiate the safety of this compound [137,141,142], This preservative has been extremely useful for soft contact lens solutions because it has the least propensity to adsorb onto or absorb into these lenses, and it has a practically nonexistent potential for sensitization. Its ad-sorption/absorption with high water and high ionic lenses can be resolved by carefully balancing formulation components [143],... 

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