Artificial tear solutions

Patients may obtain symptomatic relief by using cold compresses and artificial tears.10 If artificial tear solutions sting, recommend a preservative-free formula. 

An erodible insert developed as a potential ocular drug-delivery system is marketed as a prescription drug for the lubricant properties of the polymer base. Lacrisert is a sterile ophthalmic insert used in the treatment of moderate to severe dry eye syndrome and is usually recommended for patients unable to obtain symptomatic relief with artificial tear solutions. The insert is composed of 5 mg of hydroxypropylcellulose in a rod-shaped form about 1.27 mm diameter by about 3.5 mm long. No preservative is used, since it is essentially anhydrous. The quite rigid cellulose rod is placed in the lower conjunctival sac and first imbibes water from the tears and after several hours forms a... 

The device is generally comfortable and well accepted by many patients, but its use does have certain disadvantages. Some patients have problems with discomfort (foreign body sensation) or expulsion of the Lacrisert.The insert can be wetted with saline before insertion to improve comfort, but this can make even more difficult the insert s placement into the lower cul-de-sac, which requires a moderate amount of dexterity. Supplementation with artificial tears after insertion may improve comfort. The most common patient complaint is blurred vision associated with the intense release of polymer during the first 4 to 6 hours after instillation, from a thickened tear film.Adding such fluid as drops of NaCl 0.9% or artificial tear solution can reduce the tear film viscosity and minimize the visual complaints. As the insert dissolves it releases debris that can blur vision and cause irritation. Most patients with mild signs and symptoms of dry eye do not experience improvement with use of the insert, as compared with the use of conventional tear solutions. Because some tear secretion is necessary to dissolve the Lacrisert, KCS patients with low basal tear secretion may not benefit from or tolerate its use. 

Snibson A, Greaves JL, Soper NDW, et al. Ocular surface residence times of artificial tear solutions. Cornea 1992 11 288-293. 

Ubels J, Clousing D,Van HaitsmanT, et al. Pre-cUnical investigation of the efficacy of an artificial tear solution containing hydroxy-propyl-guar gelling agent. Curr Eye Res 2004 28 437-444. 

Wilhelmy plate wetting parameters, such as plate velocity during immersion or emersion and halting the motion of the plate after immersion or emersion, have been shown to alfect the intrinsic hysteresis, which consequently affects the overall shape of the force loop [3]. These wetting parameters were found to affect FHT differently depending on whether pure water or an aqueous artificial tear solution was employed as the wetting medium. 

Figure 26.30 Wilhelmy force loops of (A) nylon-6, (B) PMMA, and (C) PTFE plates in artificial tear solution. At the end of the first emersion, the plates were held out of the solution for (1) Omin, (2) 5 min, and (3) 40 min at a depth of 5 mm the use of tear fluid on nylon-6, PMMA, and PTFE, yielded advancing contact angles, 0D,a,i. means, and standard deviations of 68° 3, 91° 3, and 130° 1, respectively.

Hypromellose is also used as a suspending and thickening agent in topical formulations. Compared with methylcellulose, hypromellose produces aqueous solutions of greater clarity, with fewer undispersed fibers present, and is therefore preferred in formulations for ophthalmic use. Hypromellose at concentrations between 0.45-1.0% w/w may be added as a thickening agent to vehicles for eye drops and artificial tear solutions. 

Adsorption of Proteins from Artificial Tear Solutions to Poly(methyl methacrylate—2 -hydroxyethyl methacrylate) Copolymers... 

Lens hazing and protein deposition are common problems for wearers of soft contact lenses. Previous experiments with hydrophobic-hydrophilic copolymers exposed to plasma showed protein adsorption to be minimal at intermediate copolymer compositions. Adsorption of proteins from artificial tear solutions to a series of polymers and copolymers ranging in composition from 100% poly (methyl methacrylate) (PMMA) to 100% poly(2-hydroxyethyl methacrylate) (PH EM A) was measured. The total protein adsorption due to the three major proteins in tear fluid (lysozyme, albumin, and immunoglobulins) was at a minimum value at copolymer compositions containing 50% or less PH EM A. The elution of the adsorbed proteins from these polymers and copolymers with various solutions also was investigated to assess the binding mechanism. 

Figure 2 summarizes the data for the three protein adsorption experiments performed. Each curve represents the amount of protein bound to the surface after the overnight soak rinse. The top curve indicates the total amount of protein adsorbed, and is simply a summation of the data for the three proteins studied. The curve was compiled using the data from three separate adsorption experiments, each of which examined one labeled protein at a time in the artificial tear solution. 

Adsorption of Proteins from Artificial Tear Solutions 457... 

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