methylcellulose and Corneal-Diseases

In the present study, viscous solutions of cysteamine hydrochloride (CH) were prepared by using 0.5%, 1.0%, 1.5% or 3.0% of hydroxypropylmethylcellulose (HPMC) and were evaluated for their in-vitro characteristics and stability. Osmolalities, pH and viscosity of the formulations were determined. The influence of benzalkonium chloride and autoclave sterilization on solution characteristics was also investigated. For stability assessment, the viscous solutions were stored at +4 and +25 degrees C over 12 months. In-vitro characteristics and CH contents of the stored solutions were monitored. Irritation tests for the formulations were evaluated on rabbit eyes. Dialysis sac technique was used to perform in vitro release study of the solutions containing 1.0% and 1.5% HPMC. All of the viscous solutions tested showed non-newtonian (dilatant) flow behavior. Osmolality values were ranked between 351.2+/-6.2 and 355.1+/-7.9 mOsm kg(-1), and pH values were between 3.97+/-0.1 and 3.98+/-0.2 for all the solutions. Furthermore, no significant changes in dilatant behavior, osmolality or pH values of the pure HPMC solutions were observed. After addition of the excipients or CH-excipients, increased viscosity values were noted in these formulations. Neither benzalkonium chloride nor autoclave sterilization had any influence on viscosity, pH or osmolality values of the solution containing 1.5% HPMC. Stability studies showed that a faster decrease in the concentration of CH was observed in the formulations stored at 25 degrees C compared to those kept at 4 degrees C; no changes were determined in osmolality values of the solutions at all storage conditions. Increased pH and decreased viscosity values were noted in HPMC solutions containing CH and excipients, while no changes in these values were observed for pure HPMC solutions kept at 4 and 25 degrees C. In vitro release tests revealed that 81.2% and 85.3% of CH were released from the viscous solutions containing 1.5% and 1% HPMC, respectively, in 8h. No irritation was observed when the viscous solutions were tested on rabbit and human eyes.

Topics: Administration, Topical; Adult; Animals; Benzalkonium Compounds; Chemistry, Pharmaceutical; Corneal Diseases; Cysteamine; Cystinosis; Drug Administration Schedule; Drug Stability; Excipients; Eye; Female; Hot Temperature; Humans; Hydrogen-Ion Concentration; Hypromellose Derivatives; Kinetics; Male; Methylcellulose; Ophthalmic Solutions; Orphan Drug Production; Osmolar Concentration; Preservatives, Pharmaceutical; Rabbits; Solubility; Sterilization; Toxicity Tests, Acute; Viscosity

To report a case of erythema multiforme major complicated by a central corneal delle.. Case report.. An 18-year-old man recovering from erythema multiforme major complained of blurred vision and grittiness. Slit-lamp examination revealed a central corneal depression; the overlying epithelium was intact, and the stroma was thinned but lacked inflammation. The patient underwent 2 months of treatment with lubrication and autologous serum. The thinning corneal stroma thickened, and the corneal curvature returned to normal without any further complications such as corneal perforation.. Erythema multiforme major caused upper tarsus deformity and dry eye, which resulted in localized corneal dehydration and a central corneal delle.

Topics: Adolescent; Corneal Diseases; Dry Eye Syndromes; Erythema Multiforme; Eyelid Diseases; Humans; Hypromellose Derivatives; Male; Methylcellulose; Ophthalmic Solutions

Topics: Contact Lenses; Corneal Diseases; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Epithelium, Corneal; Humans; Hyaluronic Acid; Laser Coagulation; Methylcellulose

Topics: Amnion; Contact Lenses; Corneal Diseases; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Epithelium, Corneal; Humans; Hyaluronic Acid; Laser Coagulation; Methylcellulose

To describe the effect of coupling solutions used during laser photocoagulation on the ocular surface of patients with noninsulin-dependent diabetes mellitus (NIDDM).. A prospective case-controlled study.. Ninety-two eyes of 46 NIDDM patients with clinically significant macular edema, poor metabolic control of diabetes, and peripheral neuropathy and 100 eyes of 50 normal control subjects were studied. The patients' eyes were assigned to argon green focal/grid laser photocoagulation using an applanation contact lens and one of the coupling fluids; 2% methocel, Thilo-Tears Gel, 1.4% sodium hyaluronate, or 0.9% simple saline. The control subjects received time-matched three-mirror contact lens fundus examinations. All subjects underwent corneal sensitivity measurements, Schirmer test, tear film breakup time, and corneal fluorescein staining before as well as 3 and 8 days after the laser procedures and contact lens examinations. Patients with corneal problems persisting after 8 days were followed longer.. Diabetic eyes assigned to 2% methocel and 1.4% sodium hyaluronate had significantly lower mean corneal sensitivities and break-up time values as well as significantly higher mean fluorescein staining scores at all examination points after laser photocoagulation. All diabetic eyes with aqueous deficiency assigned to 2% methocel and 1.4% sodium hyaluronate developed delayed corneal epithelial healing.. The use of viscous coupling solutions during applanation contact lens-aided laser procedures may be detrimental for the corneal epithelium in poorly controlled NIDDM patients with peripheral neuropathy and coexisting aqueous deficiency.

Topics: Adult; Aged; Case-Control Studies; Contact Lenses; Corneal Diseases; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Epithelium, Corneal; Female; Fluorescein; Fluorophotometry; Humans; Hyaluronic Acid; Laser Coagulation; Macular Edema; Male; Methylcellulose; Middle Aged; Ophthalmic Solutions; Prospective Studies; Tears; Wound Healing

To study the long term toxic effects of intraocular benzalkonium chloride (BAC).. 19 patients exposed to intraocular BAC preserved viscoelastic during cataract surgery in February 1999 developed severe striate keratopathy immediately postoperatively. 16 patients, including two who underwent penetrating keratoplasty, were studied in the period April to June 2000. Ocular symptoms, visual acuity, biomicroscopy, intraocular pressure, dilated funduscopy, specular endothelial microscopy, and corneal pachymetry findings were recorded. The corneal and iris specimens of the two patients who underwent keratoplasty were studied by light, transmission, and scanning electron microscopy.. Six males and 10 females, aged 64-98 years, were studied 14-16 months postoperatively. All patients were symptomatic. 12 patients had best corrected visual acuity of 6/12 or better and four patients of between 6/18 and 6/60. Five patients had corneal epithelial oedema and 11 had Descemet's membrane folds. The central corneal thickness, 620 (SD 71) microm, in affected eyes was significantly higher (p<0.005, two tailed paired t test) than that of the contralateral eyes, 563 (SD 48) microm. The endothelial cell density was significantly lower (p<0.0001, two tailed paired t test) in affected eyes: 830 (SD 280) cells/mm2 v 2017 (SD 446) cells/mm2. The mean average cell area was significantly higher in the BAC treated eyes: 1317 (SD 385) microm2 v 521 (SD 132) microm2. There was no significant difference in the coefficient of variation of cell size between the two eyes (p=0.3, two tailed paired t test). Two corneal specimens displayed morphological features of bullous keratopathy and other non-specific abnormalities. Extracellular melanosomes were present in a portion of the iris of one case.. BAC is toxic to the corneal endothelium when used intraocularly, leading to severe striate keratopathy. This cleared in most cases but left varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required the results are excellent.

Topics: Aged; Aged, 80 and over; Benzalkonium Compounds; Cohort Studies; Corneal Diseases; Detergents; Female; Hemostatics; Humans; Hypromellose Derivatives; Male; Methylcellulose; Middle Aged; Phacoemulsification; Visual Acuity

Intrastromal injection of viscoelastic (2% methylcellulose or healon) will facilitate the separation of deep stroma during dissection of recipient stroma. Full thickness lamellar keratoplasty was performed on a smooth graft bed which approached Descemet's membrane. 21 cases with bullous keratopathy were treated and followed up for six months, post-operatively. The symptoms were controlled in all cases and 13 cases were relieved from blindness with corrected visual acuities over 0.05. The safety, efficacy and reoperability of full thickness lamellar keratoplasty with viscodelamination of cornea for treatment of bullous keratopathy make it a promising technique.

Topics: Adolescent; Adult; Aged; Aphakia, Postcataract; Corneal Diseases; Corneal Transplantation; Eye Injuries; Female; Humans; Male; Methylcellulose; Middle Aged; Visual Acuity

Topics: Cornea; Corneal Diseases; Humans; Hyperopia; Hypromellose Derivatives; Laser Therapy; Methylcellulose; Postoperative Complications

A reproducible model of an irregular corneal surface was developed to test the ability of the excimer laser to treat such surfaces. Using a 193-nm argon fluoride excimer laser set at a fluence of 160 mJ/cm2, repetition rate of 10 Hz, and 185 pulses, fresh de-epithelialized pig eyes underwent phototherapeutic ablations through a piece of stainless steel wire screen that masked the cornea. This yielded an uneven corneal surface in a grid-like pattern, with the peaks 50 microns higher than the troughs. The eyes then underwent further treatment in an attempt to smooth the center of the irregularity. Hydroxypropyl-methylcellulose 0.3% protected the valleys in 12 eyes; 2 eyes were ablated without a protecting fluid. The same laser, at the above noted settings, was used, except that both 2 Hz and 10 Hz frequencies were used. Immediately after treatment, the eyes were processed for scanning electron microscopy. The eyes treated at 2 Hz showed less surface irregularity than did those treated at 10 Hz. The eyes treated without a protecting fluid, regardless of repetition rate, had the greatest irregularities. This model is simple and reproducible, and the authors' results suggest that modifying the repetition rates of the excimer laser can influence its effectiveness in smoothing irregular corneas.

Topics: Animals; Cornea; Corneal Diseases; Disease Models, Animal; Hypromellose Derivatives; Laser Therapy; Methylcellulose; Microscopy, Electron, Scanning; Reproducibility of Results; Swine

Rough corneal surfaces may be smoothed by performing a superficial keratectomy with the 193 nm excimer laser. In order to smooth an irregular surface, a substance must be used during ablation to protect low corneal areas so that high spots are ablated preferentially. A simple, accurate, and reproducible method for modelling various corneal surface irregularities was developed. The technique uses the excimer laser to imprint the patterns of various metallic grids onto the stromal surface. The model was used to facilitate a comparison of three potential smoothing agents: 0.5% tetracaine, 2% hydroxypropylmethylcellulose, and a fluorescein-containing hyaluronate preparation. Preliminary results indicate that tetracaine may be the most efficacious smoothing agent.

Topics: Animals; Cornea; Corneal Diseases; Disease Models, Animal; Hyaluronic Acid; Hypromellose Derivatives; Laser Therapy; Methylcellulose; Microscopy, Electron, Scanning; Rabbits; Reproducibility of Results; Tetracaine

Lagophthalmos and corneal hypaesthesia are amongst the most frequently encountered lesions in leprosy and they can easily give rise to blindness. Many measures (such as eye drops, protective conoid shields, muscle exercises, surgical treatment etc.) have been used to protect the eyes under such circumstances and this paper examines the protective role of methyl cellulose and conoid shields in 41 patients. All of them had lagophthalmos (5 mm or more) and corneal hypaesthesia. They were divided into three groups. Group one had 15 leprosy control patients (27 eyes) who did not use methyl cellulose or eye shields. Group two had 16 leprosy patients (28 eyes) and they used methyl cellulose and eye shields when they felt discomfort in their eyes. Group three had 10 leprosy patients (17 eyes) and they used methyl cellulose and eye shields regularly. Statistically significant improvement was seen in group three. Further studies on larger groups of patients including the effects of different concentrations of methyl cellulose, on Schirmer test and tear break up time, may be of value.

Topics: Adult; Corneal Diseases; Eye Protective Devices; Eyelid Diseases; Female; Humans; Hypesthesia; Leprosy; Male; Methylcellulose; Ophthalmic Solutions

When we compared the effect of a hydrogel intraocular lens on the corneal endothelium of rabbits to the damage produced by uncoated methylmethacrylate intraocular lenses and methylmethacrylate lenses coated with sodium hyaluronate or methylcellulose, we found that the endothelial damage produced by the hydrogel lenses in a standard 0.25 mm2 of contact was 3.6%. This value was not significantly different from that for the control corneas (0.4%). Uncoated methylmethacrylate lenses caused 62% endothelial loss but coating them with sodium hyaluronate or methylcellulose reduced the loss to 27% and 57% respectively. The results suggested that a hydrogel intraocular lens produces minimal endothelial damage and that coating a methylmethacrylate lens with sodium hyaluronate or methylcellulose does not provide reliable endothelial protection.

Topics: Animals; Cell Count; Cornea; Corneal Diseases; Endothelium; Lenses, Intraocular; Methacrylates; Methylcellulose; Methylmethacrylates; Rabbits

Methylcellulose has been used since 1976 to prevent damage to the corneal endothelium during operations for implantation of intraocular lenses. Originally one drop of a 1% solution was placed on the artificial lens just before its insertion. Later the anterior chamber was completely filled with a 2% solution of methylcellulose before implantation. In this way it is possible to maintain a space between the cornea and iris even if vitreous pressure is present and to operate without risk to the corneal endothelium. This paper demonstrates the safety of the intraocular use of methylcellulose on the basis of over 400 operations. The substance is cheap, universally available, and can be easily prepared for intraocular use.

Topics: Corneal Diseases; Endothelium; Humans; Intraocular Pressure; Intraoperative Complications; Lenses, Intraocular; Methylcellulose

Topics: Corneal Diseases; Edema; Humans; Methylcellulose; Ophthalmic Solutions