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A comparison of slit-lamp supported versus hand-held biometry
A New Drug Delivery System Utilizing Piggyback Contact Lenses. Sano K, Tokoro T, Imai Y: Acta Ophthalmol 1996;74:243-248. Ophthalmic drugs have been found to penetrate the eye in higher concentrations when a drug delivery system (DDS) is used, which comprises a hydrophilic soft contact lens and a collagen shield soaked in a solution of the drug, instead of frequent instillation of drops or subconjunctival injection. However, previous designs have failed to provide controlled release of the drug. This article describes the design and in vitro and in vivo assessment (in rabbits) of a DDS that uses a drug plate, within a piggyback contact lens system, to release a prescribed drug at a controlled rate. “Drug plates” (8.0 -mm diameter, 0.2-mm thickness, 7.5mm base curve) were created by freeze drying a mixture of levofloxacin (fluoroquinolon antibiotic) (20,30 and 40 wt %) and polyvinyl alcohol, coated with a block styrene-(ethyl/butene)styrene (SEBS) polymer solution (5.0, 7.5, and 10.0 wt %). The drug plate was placed between a 55% water content hydrophilic lens (polyvinyl pyrrolidone) and a nonhydrophilic lens (butyl acrylate/butyl methacrylate copolymer). Optimal drug release characteristics were observed with the DDS with a 7.5 or 10.0 wt % SEBS polymer coating. The drug release profile was linear for these drug plates, irrespective of the levofloxacin concentration. In vivo assessment on albino rabbit eyes showed that the delivery of the drug to the aqueous humor with the piggyback DDS was about 15 times more effective than frequently instilling eye drops. The presence of a nonhydrophilic lens over the DDS reduced evaporation from the drug plate. However, at the current stage of development, the oxygen permeability of the combined system is lower than that recommended for the safe daily wear of contact lenses; therefore, the design of this system requires modification before use in human eyes. Nevertheless, the authors suggest that, with the benefits to he obtained from such a DDS and the frequent advances in contact lens materials and molding technology, this piggyback system may be clinically applicable in the near future.
A Comparison of Slit-Lamp Supported Versus Hand-Held Biometry. Whelehan IM, Heyworth I?, Tabandeh H, McGuigan S, Foss AJE: Eye 1996;10:514-516. Accurate determination of the axial length of the eye is important before cataract extraction in order to implant an ICLC, Vol. 23, November/December, 1996 0 Ebevier Science Inc. 1996 655 Avenue of the Americas, New York, NY 10010
intraocular lens of correct power. Inaccuracies can lead to asthenopia due to diplopia or altered depth perception. Slitlamp biometry is the most common method for determining the axial length but can be difficult in elderly, infirm patients, in those with spondylosis, or in children, because of the necessity of maintaining the head against a forehead and chin rest. An alternative method is to hold the ultrasound probe manually, allowing the patient to retain a more comfortable position. This article compares the accuracy of slit-lamp vs. hand-held biometry. Thirty-two subjects, undergoing extracapsular cataract extraction with intraocular lens implantation, took part in the study. Both forms of biometry were performed on each subject. The results of either the slit-lamp or hand-held biometry were selected randomly and were used to establish the appropriate intraocular lens implant power for a desired refractive outcome by use of the SRK-T formula. No significant intrasubject variation in axial length was observed between the slitlamp and the hand-held biometry techniques (p = 0.09). No clinically or statistically significant difference in refractive outcome was found when the power calculations for the two methods were compared (p = 0.91). The results suggest that hand-held biometry is an acceptable altemative to slit-lamp biometry and may be useful in cases where the patient is unable to manage the conventional slit-lamp technique.
Viscous Carbomer Eye Drops in Patients With Dry Eyes: Efficacy and Safety. A Randomised, Open, Cross-Over, Multicentre Study. Mamer K, Mailer PM, Dillon M, Rask-Pedersen E. Acta Ophthalmol 1996;74:249-252. Artificial tear supplements remain the most common therapy for dry eye. Often, these preparations contain poly vinyl alcohol (PVA), cellulose derivatives, or dextran; however, their duration of action is short, and consequently, frequent instillation is required to provide relief of dry eye symptoms. This article compared the efficacy of a nonpreserved, carbomer-containing preparation, Lubrithal@ (Leo Pharmaceutical Products), with a preparation containing PVA (Lacril@/Liquifilm@, Allergan). Sixty-one patients with at least one sign and symptom of dry eye were recruited for the randomized, open, crossover study, which took place in seven centers in Denmark. Each subject underwent the two treatments consecutively, for 2 weeks each, with no break between them. The order of treatment 0892-8967/96/$15.00 PII SO892-8967(96)00102-2
A Comparison of Slit-Lamp Supported Versus Hand-Held Biometry. Whelehan IM, Heyworth I?, Tabandeh H, McGuigan S, Foss AJE: Eye 1996;10:514-516. Accurate determination of the axial length of the eye is important before cataract extraction in order to implant an ICLC, Vol. 23, November/December, 1996 0 Ebevier Science Inc. 1996 655 Avenue of the Americas, New York, NY 10010
intraocular lens of correct power. Inaccuracies can lead to asthenopia due to diplopia or altered depth perception. Slitlamp biometry is the most common method for determining the axial length but can be difficult in elderly, infirm patients, in those with spondylosis, or in children, because of the necessity of maintaining the head against a forehead and chin rest. An alternative method is to hold the ultrasound probe manually, allowing the patient to retain a more comfortable position. This article compares the accuracy of slit-lamp vs. hand-held biometry. Thirty-two subjects, undergoing extracapsular cataract extraction with intraocular lens implantation, took part in the study. Both forms of biometry were performed on each subject. The results of either the slit-lamp or hand-held biometry were selected randomly and were used to establish the appropriate intraocular lens implant power for a desired refractive outcome by use of the SRK-T formula. No significant intrasubject variation in axial length was observed between the slitlamp and the hand-held biometry techniques (p = 0.09). No clinically or statistically significant difference in refractive outcome was found when the power calculations for the two methods were compared (p = 0.91). The results suggest that hand-held biometry is an acceptable altemative to slit-lamp biometry and may be useful in cases where the patient is unable to manage the conventional slit-lamp technique.
Viscous Carbomer Eye Drops in Patients With Dry Eyes: Efficacy and Safety. A Randomised, Open, Cross-Over, Multicentre Study. Mamer K, Mailer PM, Dillon M, Rask-Pedersen E. Acta Ophthalmol 1996;74:249-252. Artificial tear supplements remain the most common therapy for dry eye. Often, these preparations contain poly vinyl alcohol (PVA), cellulose derivatives, or dextran; however, their duration of action is short, and consequently, frequent instillation is required to provide relief of dry eye symptoms. This article compared the efficacy of a nonpreserved, carbomer-containing preparation, Lubrithal@ (Leo Pharmaceutical Products), with a preparation containing PVA (Lacril@/Liquifilm@, Allergan). Sixty-one patients with at least one sign and symptom of dry eye were recruited for the randomized, open, crossover study, which took place in seven centers in Denmark. Each subject underwent the two treatments consecutively, for 2 weeks each, with no break between them. The order of treatment 0892-8967/96/$15.00 PII SO892-8967(96)00102-2