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1.
Braz J Med Biol Res ; 50(7): e5901, 2017 Jul 03.
Article in English | MEDLINE | ID: mdl-28678917

ABSTRACT

We aimed to quantify the penetration of ciprofloxacin, ofloxacin, and moxifloxacin into the cornea and aqueous humor of cadaver eyes. A total of 60 enucleated eyes, not eligible for corneal transplantation, were divided into three groups and immersed in commercial solutions of 0.3% ciprofloxacin, 0.3% ofloxacin, or 0.5% moxifloxacin for 10 min. Whole corneas and samples of aqueous humor were then harvested and frozen, and drug concentrations analyzed by liquid chromatography tandem mass spectrometry. The mean corneal concentration of moxifloxacin was twice as high as ofloxacin, and the latter was twice as high as ciprofloxacin. The mean concentration of moxifloxacin in the aqueous humor was four times higher than the other antibiotics, and the mean concentrations of ciprofloxacin and ofloxacin were statistically similar. The amount of drug that penetrated the anterior chamber after a 10-min immersion was far below the safe limit of endothelial toxicity of each preparation. Moxifloxacin demonstrated far superior penetration into the cornea and anterior chamber of cadaver eyes compared to ciprofloxacin and ofloxacin. One should not expect endothelial toxicity with the commercial eye drops of ciprofloxacin, ofloxacin, and moxifloxacin that reach the anterior chamber through the cornea.


Subject(s)
Aqueous Humor/drug effects , Ciprofloxacin/pharmacokinetics , Cornea/drug effects , Fluoroquinolones/pharmacokinetics , Ofloxacin/pharmacokinetics , Bayes Theorem , Cadaver , Eye Enucleation , Humans , Moxifloxacin
2.
Braz. j. med. biol. res ; 50(7): e5901, 2017. tab
Article in English | LILACS | ID: biblio-951703

ABSTRACT

We aimed to quantify the penetration of ciprofloxacin, ofloxacin, and moxifloxacin into the cornea and aqueous humor of cadaver eyes. A total of 60 enucleated eyes, not eligible for corneal transplantation, were divided into three groups and immersed in commercial solutions of 0.3% ciprofloxacin, 0.3% ofloxacin, or 0.5% moxifloxacin for 10 min. Whole corneas and samples of aqueous humor were then harvested and frozen, and drug concentrations analyzed by liquid chromatography tandem mass spectrometry. The mean corneal concentration of moxifloxacin was twice as high as ofloxacin, and the latter was twice as high as ciprofloxacin. The mean concentration of moxifloxacin in the aqueous humor was four times higher than the other antibiotics, and the mean concentrations of ciprofloxacin and ofloxacin were statistically similar. The amount of drug that penetrated the anterior chamber after a 10-min immersion was far below the safe limit of endothelial toxicity of each preparation. Moxifloxacin demonstrated far superior penetration into the cornea and anterior chamber of cadaver eyes compared to ciprofloxacin and ofloxacin. One should not expect endothelial toxicity with the commercial eye drops of ciprofloxacin, ofloxacin, and moxifloxacin that reach the anterior chamber through the cornea.


Subject(s)
Humans , Aqueous Humor/drug effects , Ofloxacin/pharmacokinetics , Ciprofloxacin/pharmacokinetics , Cornea/drug effects , Fluoroquinolones/pharmacokinetics , Cadaver , Eye Enucleation , Bayes Theorem , Moxifloxacin
3.
Braz. j. med. biol. res ; 47(6): 470-477, 06/2014. tab, graf
Article in English | LILACS | ID: lil-709452

ABSTRACT

The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography. Segments with active replication (on) and those with no cell division (off) were intermingled in all regions of the tissue, suggesting that the renewal of the epithelial surface of the cornea followed an on/off alternating pattern. In the limbus, heavy labeling of the outermost layers was observed, coupled with a few or no labeled nuclei in the basal stratum. This suggests that this region is a site of rapid cell differentiation and does not contain many slow-cycling cells. The conspicuous and protracted labeling of the basal layer of the corneal epithelium suggests that its cells undergo repeated cycles of replication before being sent to the suprabasal strata. This replication model is prone to generate label-retaining cells. Thus, if these are adult stem cells, one must conclude that they reside in the corneal basal layer and not the limbal basal layer. One may also infer that the basal cells of the cornea and not of the limbus are the ones with the main burden of renewing the corneal epithelium. No particular role in this process could be assigned to the cells of the basal layer of the limbal epithelium.


Subject(s)
Animals , Male , Rabbits , Epithelium, Corneal/anatomy & histology , Epithelium, Corneal/physiology , Limbus Corneae/cytology , Stem Cells/physiology , Autoradiography , Cell Proliferation , Cell Movement/physiology , Cornea/anatomy & histology , Eye/anatomy & histology , Intravitreal Injections , Thymidine , Tritium
4.
Braz J Med Biol Res ; 47(6): 470-7, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24820068

ABSTRACT

The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography. Segments with active replication (on) and those with no cell division (off) were intermingled in all regions of the tissue, suggesting that the renewal of the epithelial surface of the cornea followed an on/off alternating pattern. In the limbus, heavy labeling of the outermost layers was observed, coupled with a few or no labeled nuclei in the basal stratum. This suggests that this region is a site of rapid cell differentiation and does not contain many slow-cycling cells. The conspicuous and protracted labeling of the basal layer of the corneal epithelium suggests that its cells undergo repeated cycles of replication before being sent to the suprabasal strata. This replication model is prone to generate label-retaining cells. Thus, if these are adult stem cells, one must conclude that they reside in the corneal basal layer and not the limbal basal layer. One may also infer that the basal cells of the cornea and not of the limbus are the ones with the main burden of renewing the corneal epithelium. No particular role in this process could be assigned to the cells of the basal layer of the limbal epithelium.


Subject(s)
Epithelium, Corneal/anatomy & histology , Epithelium, Corneal/physiology , Limbus Corneae/cytology , Stem Cells/physiology , Animals , Autoradiography , Cell Movement/physiology , Cell Proliferation , Cornea/anatomy & histology , Eye/anatomy & histology , Intravitreal Injections , Male , Rabbits , Thymidine , Tritium
5.
Braz J Med Biol Res ; 45(5): 408-10, 2012 May.
Article in English | MEDLINE | ID: mdl-22370709

ABSTRACT

How is the corneal epithelium restored when all of it plus the limbus have been eliminated? This investigation explored the possibility that this may be achieved through the conjunctival epithelium. The corneal epithelium of the right eye of 12 rabbits (Oryctolagus cuniculus) was totally scraped followed by surgical excision of the limbus plus 1.0-1.5 mm of the adjacent conjunctiva. Antibiotics and corticosteroids were applied for 1 week after surgery. Histological and immunohistochemical techniques were used to monitor the events taking place on the eye surface 2 weeks and 1, 3 and 6 months thereafter. Initially, the corneal surface was covered by conjunctival-like epithelium. After 1 month and more prominently at 3 and 6 months an epithelium displaying the morphological features of the cornea and reacting with the AE5 antibody was covering the central region. It is likely that the corneal epithelium originated from undifferentiated cells of the conjunctiva interacting with the corneal stroma.


Subject(s)
Cornea/physiology , Re-Epithelialization/physiology , Animals , Cornea/surgery , Debridement , Epithelium, Corneal/physiology , Epithelium, Corneal/surgery , Limbus Corneae/surgery , Male , Rabbits
6.
Phys Med Biol ; 43(5): 1303-16, 1998 May.
Article in English | MEDLINE | ID: mdl-9623657

ABSTRACT

An automatic and objective system for measuring ocular refractive errors (myopia, hyperopia and astigmatism) was developed. The system consists of projecting a light target (a ring), using a diode laser (lambda = 850 nm), at the fundus of the patient's eye. The light beams scattered from the retina are submitted to an optical system and are analysed with regard to their vergence by a CCD detector (matrix). This system uses the same basic principle for the projection of beams into the tested eye as some commercial refractors, but it is innovative regarding the ring-shaped measuring target for the projection system and the detection system where a matrix detector provides a wider range of measurement and a less complex system for the optical alignment. Also a dedicated electronic circuit was not necessary for treating the electronic signals from the detector (as the usual refractors do); instead a commercial frame grabber was used and software based on the heuristic search technique was developed. All the guiding equations that describe the system as well as the image processing procedure are presented in detail. Measurements in model eyes and in human eyes are in good agreement with retinoscopic measurements and they are also as precise as these kinds of measurements require (0.125D and 5 degrees).


Subject(s)
Image Interpretation, Computer-Assisted , Image Processing, Computer-Assisted , Lasers , Refractive Errors/diagnosis , Astigmatism/diagnosis , Automation , Calibration , Humans , Hyperopia/diagnosis , Light , Myopia/diagnosis , Refraction, Ocular , Retina , Scattering, Radiation
7.
Ophthalmic Physiol Opt ; 16(2): 184-6, 1996 Mar.
Article in English | MEDLINE | ID: mdl-8762782

ABSTRACT

The available methods for the exact calculation of centre thickness presuppose that one knows simultaneously both surfaces of the lens and that the lens' power is determined afterwards. However, this approach is of secondary importance in practical situations. The issue in daily practice is the determination of the centre thickness of lenses that already have explicit vertex powers. In such cases one can set only one surface. The other has to be calculated following the prescription, the known surface and the optical effect of the centre thickness. Exact solution for this problem leads to four expressions, reflecting the number of ways one can treat it. Two of them are complete second-order algebraic equations and the other two, complete third-order algebraic equations. The practical value of the latter is limited by the fact that one cannot always obtain their three roots by pure algebraic procedures.


Subject(s)
Contact Lenses , Eyeglasses , Models, Theoretical , Optometry/methods
8.
Ophthalmic Physiol Opt ; 15(2): 153-6, 1995 Mar.
Article in English | MEDLINE | ID: mdl-7659411

ABSTRACT

This paper presents a three-step method for the addition of obliquely crossed spherocylinders. Contrary to other methods it does not require algorithms or complicated abstract concepts to secure the consistency of the results.


Subject(s)
Lenses , Algorithms , Optics and Photonics
9.
Am J Optom Physiol Opt ; 63(9): 770-3, 1986 Sep.
Article in English | MEDLINE | ID: mdl-3777128

ABSTRACT

A HP program for a quick and precise determination of the center thickness of convex spectacle lenses is presented. The program uses 150 lines of programming and 10 storage registers. With the exception of the center thickness and one of the surface powers all the other parameters must be known.


Subject(s)
Eyeglasses , Lenses , Software , Optics and Photonics
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