A confocal microscopic study of advancing wavelike epitheliopathy.
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Corneal Diseases↗
Biomedical subjects
H E Kaufman
Publications and source records attributed to H E Kaufman.
Trifluridine, cidofovir, and penciclovir in the treatment of experimental herpetic keratitis.
OBJECTIVE: To compare trifluridine eyedrops, cidofovir eyedrops, and penciclovir ophthalmic ointment for the treatment of herpes simplex virus type 1 keratitis. METHODS: New Zealand white rabbits were infected with the McKrae strain of herpes simplex virus type 1. Three days after viral inoculation, the rabbits were randomly assigned to treatment with 1% trifluridine, 0.2% cidofovir, 3% penciclovir ointment, or phosphate-buffered saline (for control) on various schedules. The severity of keratitis was graded in a masked manner. RESULTS: Treatment with any of the antiviral drugs resulted in significantly less severe keratitis than treatment with phosphate-buffered saline. There was no statistically significant difference between eyes given trifluridine 2, 4, or 7 times a day and eyes given cidofovir 2 times a day (P=.06, P=.43, and P=.19, respectively, using the F test of the analysis of variance). Cidofovir given twice a day was significantly more effective than penciclovir given either 2 or 4 times a day (P<.001 and P=.002, respectively). Even with once-a-day dosage, all 3 drugs were significantly more effective than phosphate-buffered saline (P<.001 for all). There was no significant difference between once-a-day trifluridine and cidofovir treatments (P=.17). Trifluridine administered 5 times a day was as effective as 1% cidofovir. A similar degree of punctate keratitis was seen after 4 to 5 days in eyes treated with trifluridine at the highest frequency, 1% cidofovir, or penciclovir ointment. CONCLUSION: Trifluridine treatment was highly effective in this rabbit model, even when given only once a day. Treatment with cidofovir was as effective as that with trifluridine. CLINICAL RELEVANCE: Cidofovir and penciclovir treatments may prove to be effective against epithelial keratitis. Clinical trials of trifluridine, cidofovir, and penciclovir with lower treatment frequencies appear to be warranted.
Acyclovir↗
Characterization of fibrous retrocorneal membrane by confocal microscopy.
PURPOSE: To study the appearance of a fibrous retrocorneal membrane as seen by confocal microscopy. METHODS: A 67-year-old white woman with a history of multiple ocular surgeries, including repeated penetrating keratoplasties for aphakic bullous keratopathy, developed a retrocorneal membrane in the right eye. The membrane was first noticed 3 years after the last corneal transplant and remained stable subsequently. The patient was examined by in vivo white light tandem-scanning confocal microscopy. RESULTS: At the level of the retrocorneal membrane, confocal microscopy disclosed the presence of a hyperreflective fibrous-appearing layer. Normal endothelial cells could not be found. Anterior to the hyperreflective layer, activated keratocytes were identified. CONCLUSION: Confocal microscopy may allow noninvasive diagnosis of fibrous retrocorneal membrane. Additionally, our data suggest that the posterior keratocytes might play a role in the production and deposition of fibrous tissue.
Aged↗
9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, suppresses herpes virus reactivation in mice.
In cells of the nervous system, which have little or no cellular thymidine kinase, the pharmacologic inhibition of viral thymidine kinase may prevent the reactivation of herpes virus, which requires phosphorylated thymidine for replication. We tested a newly synthesized inhibitor of viral thymidine kinase, 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG) for its capacity to suppress the reactivation of herpes simplex virus type 1 (HSV-1) in vivo. Mice, latently infected with McKrae strain HSV-1, were treated with intraperitoneal injections of HBPG in a corn oil vehicle (200 mg/kg every 3 h for a total of ten doses), and subjected to hyperthermic stress to stimulate viral reactivation immediately before the third treatment. Three h after the last treatment, the mice were sacrificed, and the presence of infectious virus was determined by culture of ocular surface swabs and trigeminal ganglionic homogenates. Additionally, viral DNA in ganglionic extracts was analyzed by quantitative PCR. Controls included latently infected, stressed animals receiving injections of corn oil vehicle only, and latently infected, drug- and vehicle-treated, unstressed animals. HBPG had a statistically significant inhibitory effect on hyperthermia-induced viral reactivation. Homogenates of trigeminal ganglia and ocular surface swabs from HBPG-treated animals were less likely to contain infectious virus than those of infected, vehicle-treated, stressed controls (P < 0.005, ANOVA). Unstressed controls showed no reactivation. Quantitation of viral DNA in ganglionic extracts demonstrated a 100-fold reduction in the amount of viral DNA in the ganglia of HBPG-treated animals, compared with vehicle-treated controls (P < 0.05, ANOVA). The results indicate that HBPG has an inhibitory effect when given systemically for the suppression of herpes virus reactivation in mice.
Animals↗
Coping with the itchy-burnies: the management of allergic conjunctivitis.
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Anti-Inflammatory Agents↗
Effect of 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, on clinical recurrences of ocular herpetic keratitis in squirrel monkeys.
9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG) is a new viral thymidine kinase inhibitor that we tested for the ability to prevent recurrences of herpetic keratitis. Eighteen squirrel monkeys (Saimiri scuireus) were infected in both corneas with the Rodanus strain of herpes simplex virus type 1 (HSV-1). All corneas showed typical dendritic keratitis 3 days after infection, followed by spontaneous healing. On day 21, the monkeys were randomized into two coded groups and ocular examinations were begun. One group received intraperitoneal (i.p.) injections of HBPG, 150 mg/kg, in a corn oil suspension every 8 h, and the other group received i.p. injections of the corn oil vehicle only. On day 22, recurrences were induced by reducing the temperature of the room in the late afternoon so that a low of 18 degrees C was achieved during the night. After the morning treatment, room temperature was raised to the normal ambient temperature (24-27 degrees C), and treatment was discontinued. Treatment was reinstituted on day 27, the room temperature was lowered again on day 28, and treatment was again discontinued as before. Third and fourth cycles of treatment and cold stress were begun on days 34 and 69. Ocular examinations were continued until day 73, at which point the code was broken. We found that the HBPG treatment significantly reduced the number of corneas with recurrences during the treatment periods, compared with recurrences in untreated, cold-stressed animals (P = 0.01).
Animals↗
Quantitation of herpes simplex virus type 1 DNA and latency-associated transcripts in rabbit trigeminal ganglia demonstrates a stable reservoir of viral nucleic acids during latency.
In this investigation we determined the dynamics of herpes simplex virus type 1 (HSV-1) DNA and latency-associated transcripts (LAT) in the latently infected rabbit trigeminal ganglion. Rabbit eyes were infected with either the McKrae strain or the l7Syn+ strain of HSV-1. Rabbits were sacrificed between 5 and 360 days after infection and their trigeminal ganglia were analyzed for the number of HSV DNA genomes and the number of neuronal cells expressing LAT. There was no statistically significant change in the number of HSV genomes or the number of neuronal cells expressing LAT in these ganglia between 20 and 360 days after infection. For both strains, the amount of HSV DNA averaged 16.8 genomes per 100 cells, and 9.2% of the neurons expressed LAT. There were 17 to 34 HSV genomes per LAT-expressing neuronal cell. The number of LAT-expressing neurons did not change over the 360 days. Spontaneous reactivation (HSV-1 recovery in tear film) and recurrence (HSV-1-specific epithelial lesions) occurred during the period of this study; however, these events did not alter the quantity of HSV-1 DNA or the number of LAT-expressing cells. These results suggest that after the latent infection is established, the viral DNA in the ganglia does not replicate to any measurable extent over long periods of latency, since no significant change in the number of HSV genomes occurs. The results also suggest that only a very small number of latently infected neuronal cells are needed to produce infectious HSV-1 during reactivation.
Actins↗
Risk factors for herpes simplex virus epithelial keratitis recurring during treatment of stromal keratitis or iridocyclitis. Herpetic Eye Disease Study Group.
AIMS: Possible risk factors were evaluated for herpes simplex virus (HSV) epithelial keratitis in patients with stromal keratouveitis. METHODS: The study population included 260 patients who had active stromal keratitis and/or iridocyclitis without epithelial disease and who were enrolled in one of three clinical trials of the Herpetic Eye Disease Study. Study treatment involved a 10 week course of topical placebo, topical prednisolone phosphate, or topical prednisolone phosphate with oral acyclovir. All groups received topical trifluridine four times daily for 3 weeks then twice daily for another 7 weeks. Patients were examined for HSV epithelial keratitis for 16 weeks. RESULTS: Dendritic or geographic epithelial keratitis occurred in 12 (4.6%) study patients. Adverse effects attributable to trifluridine prophylaxis were acute allergic blepharoconjunctivitis in 10 (3.8%) study patients and corneal epithelial erosions in 11 (4.2%) study patients. No significant difference in the occurrence of HSV epithelial keratitis was found among the study treatment groups: one (2.0%) of 49 topical placebo treated patients, nine (6.5%) of 138 patients treated with topical corticosteroids without acyclovir, and two (2.7%) of 73 patients treated with topical corticosteroids and oral acyclovir. Univariate exponential models suggested that patients with a history of previous HSV epithelial keratitis and non-white patients were more likely to develop HSV epithelial keratitis during treatment of stromal keratouveitis. CONCLUSION: Individuals with prior HSV epithelial keratitis and certain ethnic groups may have a higher rate of recurrent epithelial keratitis during the acute treatment of HSV stromal keratouveitis.
Acyclovir↗
Propranolol suppression of ocular HSV-1 recurrence and associated corneal lesions following spontaneous reactivation in the rabbit.
PURPOSE: Hyperthermia has been shown to induce HSV-1 ocular shedding in mice. Systemic administration of propranolol significantly reduced the recovery of infectious virus in the tears, cornea, and trigeminal ganglia of mice subjected to hyperthermia. The present study was performed to determine the effects of systemic propranolol on ocular shedding and recurrent corneal epithelial lesions in the rabbit model. METHODS: New Zealand white rabbits were infected with HSV-1 strain McKrae or 17Syn+. After latency was established, the animals were treated with systemic propranolol or saline (control) and examined by slit lamp biomicroscopy for corneal lesion. Tear film swabs were cultured to determine the frequency and duration of viral shedding. RESULTS: Propranolol caused a significant reduction in the frequency and duration of ocular HSV-1 shedding and a reduction in the frequency of recurrent corneal epithelia disease, compared with saline treatment. CONCLUSIONS: These results suggest that beta-adrenergic receptor blockers such as propranolol could be useful in suppressing HSV-1 ocular recurrences and corneal disease.
Adrenergic beta-Antagonists↗
Propranolol suppresses reactivation of herpesvirus.
Herpes simplex virus type 1 (HSV-1) reactivates from the nervous system and causes recurrent disease in end organs such as the eye and the lips. We found that the beta-adrenergic receptor blocker, propranolol, reduces HSV-1 reactivation in an animal model. Mice latent for McKrae strain HSV-1 were injected with propranolol or saline once a day for 3 successive days, and subjected to a brief period of hyperthermia on the second day to induce reactivation. Twenty-four hours after the third injection, swabs of the ocular surface and homogenates of the corneas and trigeminal ganglia were analyzed for the presence of infectious virus and viral DNA. Treatment with propranolol significantly decreased the appearance of infectious virus in the tear film, cornea, and trigeminal ganglia (P < 0.05, chi 2-test). The results suggest a possible new pharmacologic approach to suppressing herpesvirus reactivation in the nervous system and thereby preventing recurrent disease.
Adrenergic beta-Antagonists↗
Collagen as a delivery system for hydrophobic drugs: studies with cyclosporine.
The time-honored approach to delivering drugs to the ocular surface is through the use of liquid drops and semisolid ointments. Such delivery systems, however, are not efficient at delivering therapeutic concentrations of drugs to the cornea and intraocularly. Over the past several years, we tested the biopolymer, collagen, as a means of delivering both hydrophilic and hydrophobic drugs to the ocular surface. This study summarizes results obtained using the hydrophobic drug, cyclosporine, incorporated into collagen shields and collagen particles. Corn oil drops containing cyclosporine were used as the control. Groups of anesthetized rabbits were fitted with collagen shields containing cyclosporine, treated topically with collagen particles containing cyclosporine suspended in an ocular surface lubricant, or given topical drops of corn oil containing cyclosporine. At intervals after a single treatment with one of the drug formulations, corneas, aqueous humor, and blood were collected for analysis of cyclosporine concentration. With either of the two collagen vehicles, peak concentrations of the drug were found in the cornea 4 hours after application. The corn oil vehicle yielded a significantly lower and earlier peak concentration (1 hour after application). By 8 hours, significant amounts of the drug were still present in the corneas of the collagen-treated animals, whereas drug levels in the corn oil treatment group had returned to baseline. Drug delivery profiles in the aqueous humor were similar, except that the amounts of drug were five times lower. No cyclosporine was detected in the blood from any of the treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Cyclosporine in collagen particles: corneal penetration and suppression of allograft rejection.
The purpose of this study was to determine the pharmacokinetics of cyclosporine in the cornea and aqueous humor following topical application in collagen particles and to determine the capacity of cyclosporine in collagen particles to suppress corneal allograft rejection. Cyclosporine was prepared for topical application in three vehicles: collagen particles suspended in methylcellulose, collagen shields, and corn oil. Rabbit eyes were treated with a single application of one formulation. Corneas, aqueous humor samples, and blood samples were collected at 2, 4, 8, 12, and 24 hours. Peak concentrations of drug were reached between 2 and 4 hours in the cornea and between 4 and 8 hours in the aqueous humor. No drug was found in the blood. Collagen particles and shields produced significantly higher concentrations of cyclosporine in the aqueous humor and cornea, compared with corn oil drops, at virtually all time points. In the second part of the study, rabbits with vascularized corneas underwent corneal transplantation and were treated with one of the formulations beginning either at the time of transplantation (prophylactically) or at the first sign of an allograft immune reaction (delayed treatment). Cyclosporine delivered in collagen particles was effective in preventing primary corneal allograft rejection in nearly all of the grafts (96%) treated prophylactically, and in 67% of the grafts treated when signs of the first stage (grade 1) of immune graft reaction were observed. Grafts treated with cyclosporine in collagen shields showed similar survival rates (87% and 64%, respectively), whereas only 40% of the grafts treated prophylactically and only one (18%) receiving delayed treatment with the corn oil preparation survived. These results demonstrate the efficacy of collagen particles for delivery of hydrophobic drugs to the ocular surface and the potential for preventing corneal graft rejection with topically applied cyclosporine in a collagen-particle vehicle.
Administration, Topical↗
Tear film, pharmacology of eye drops, and toxicity.
Various new topical ophthalmic drug delivery systems show promise for increasing bioavailability, reducing epithelial toxicity, and improving patient compliance. Microparticulates are drug-containing polymeric particles that are placed in the fornix and release ocular medication by diffusion, chemical reaction, polymer degradation, or ion exchange and can be used to deliver many topical ophthalmic medications, including antibiotics and antimetabolites. Soft drugs are activated enzymatically at the site of application and are rapidly converted to inactive metabolites when exposed to the ocular environment, improving bioavailability at the target site, and reducing the potential for ocular and systemic side effects. Applications include soft beta-blockers, soft corticosteroids, and soft anticholinergics. Collasomes are made up of collagen pieces suspended in a viscous vehicle; this formulation is similar to that of corneal collagen shields, but is more useful for chronic therapy because the collasomes can be instilled by the patient and cause less blurring of vision. Potential uses include delivery of hydrophobic antimetabolites such as cyclosporine to prevent graft rejection and delivery of lipids for the therapy of dry eyes. Ideal replacements for dysfunctional tear layers, especially the lipid layer, have not yet been developed. The toxic effects of preservatives in topical ocular medications, particularly in artificial tears, often outweigh the benefits and preservative-free tear preparations are almost always preferable.
Animals↗
Cold stress-induced recurrences of herpetic keratitis in the squirrel monkey.
PURPOSE: Models of recurrent herpetic keratitis that depend on tissue damage or immunosuppression have been described. The authors report a model that depends only on minimal temperature stress to produce clinical recurrences in a small primate. METHODS: Squirrel monkeys (Saimiri sciureus) infected by the ocular route with the Rodanus strain of herpesvirus type 1 (HSV-1) were exposed to temperatures approximately 5 degrees C lower than the usual ambient temperature for periods as short as 12 hours. RESULTS: The corneas showed more or larger lesions typical of recurrent herpetic keratitis than are usually seen in these animals under normal conditions. Statistical analysis showed that there were significantly higher frequencies of epithelial keratitis at 18 degrees C and 20 degrees C (P < 0.0001). CONCLUSIONS: A minimal temperature change produced significant recurrences in this small animal within a short time. Tissues were not damaged to produce the recurrences. This approach may provide an efficient primate model for rapid testing of drugs to prevent clinical recurrence of ocular herpetic keratitis.
Animals↗
Confocal microscopy of corneal graft rejection.
Corneal allografts were transplanted into inflamed and vascularized graft beds in rabbit eyes. The grafts were examined every 4 days by slit-lamp biomicroscopy and scanning confocal microscopy. Confocal images were recorded with a video camera and computer enhanced in real-time. Layers of the cornea were visualized in serial optical sections parallel to the epithelium. In the third postoperative week, signs of graft rejection were observed; slit-lamp examination revealed a circumferential line of epithelial rejection, along with cloudiness and edema. Vessels were observed growing into the graft. By confocal microscopy, infiltrating cells were seen in the graft stroma. Foci of cells were especially pronounced around the sutures. Scattered leukocyte infiltrates were prominent at capillary terminals. There was an accompanying reduction in the stromal keratocyte density in the region of the infiltrate. Additionally, various degrees of fibrosis were noted around each suture and at the host-graft interface. Confocal microscopy may provide a valuable clinical tool for determining the earliest indicators of an antigraft immune response, and as an aid in the differential diagnosis of other inflammatory conditions of the cornea.
Animals↗
In vivo confocal microscopy of corneal wound healing after excimer laser photorefractive keratectomy.
We used real-time scanning confocal microscopy to evaluate early changes in corneal wound healing after excimer laser photorefractive keratectomy (PRK). Adult New Zealand White rabbits were given photorefractive keratectomy treatments appropriate for 5.00 to 8.00 D of myopia (44.5 to 71.0 micros depth, with a 5-mm diameter treatment zone). Daily confocal microscopic examinations showed acute loss of keratocytes in the anterior corneal stroma by 5 hours; losses were maximal between 24 and 48 hours for 5.00 D and 6.00 D ablations and between 72 and 96 hours for 7.00 D and 8.00 D ablations. The oval nuclei of normal keratocytes gave way to spindle-shaped fibroblasts accompanied by an accumulation of fibrillary extracellular matrix. Fibroblasts density increased toward the end of the week. Deeper ablations resulted in a longer period of keratocyte depletion and delayed onset of fibroblast activity. No epithelial, deep stromal, or endothelial abnormalities were detected, nor was stromal inflammation found. Light microscopy 1 week after PRK revealed superficial fibroplasia, which correlated with the en face images obtained with real-time in vivo confocal microscopy. The confocal microscope has a number of advantages as a clinical tool for investigation of laser-induced changes in corneal keratocytes and the stromal matrix, which may play a role in determining visual outcome after PRK.
Animals↗
Quantitative histological studies of primate corneas after excimer laser photorefractive keratectomy.
OBJECTIVE: To evaluate histological changes in the primate cornea after excimer laser photorefractive keratectomy (PRK) and to correlate them with clinical observations. METHODS: Sixteen African green monkey (Cercopithecus aethiops sabaeus) corneas were examined by light and transmission electron microscopy 6 weeks to 18 months after 1.5- or 3-diopter PRK. RESULTS: All specimens had a smooth stromal surface surrounded by a smooth, centrally tapered Bowman's layer. Epithelial thickness appeared to peak 12 months after PRK. The trend was for the epithelium to be thickest in the central-treated area; this phenomenon was more obvious in the 3-diopter-treated corneas. The numbers of activated keratocytes beneath the treated zone peaked at 4 months and decreased thereafter, while the numbers in the untreated areas decreased in the first 2 months after surgery, increased by 4 months, and did not change thereafter. Regenerated basal lamina averaged 86% intact over ablated areas; thickness was normal and no duplications were seen. Overall, the density of hemidesmosomes was significantly less in ablated areas compared with unablated areas. CONCLUSIONS: These findings support the relationship between clinical observations of corneal haze after PRK, reestablishment of the epithelial cell layer, and the potential for stromal remodeling by active fibroblastic keratocytes beneath the ablation zone. Overall, quantification of several morphological parameters indicated that the values for the treated zone tended, with time, to approach those of the untreated cornea after PRK.
Animals↗
Quantification of real-time confocal images of the human cornea.
Real-time confocal microscopy was used to obtain images of the surface cells of the cornea in vivo in human subjects and in non-human primates. The surface cells represent the barrier between the tear layer and the internal cellular environment and as such, the state of these cells is indicative of the health of the cornea. In our study, confocal microscopy of the surface cells revealed prominent, centrally located nuclei. With the use of a series of image analysis procedures, the nuclei were located automatically and distances to the nearest neighbors were determined. Comparison of these procedures in 8 human corneas and 1 non-human primate cornea showed that unaided computer analysis of the surface cells was as accurate as manual location of the cell nuclei. The distribution of nearest-neighbor distances was found to be best fitted by a gamma distribution. Simulation of a condition marked by loss of surface cells demonstrated that the alpha (shape) and beta (scale) parameters could be used to compare the distribution of nearest-neighbor distances. Thus, confocal microscopy coupled with these image analysis and statistical procedures could provide an objective, quantitative approach to monitoring the epithelial barrier under clinical and experimental conditions, for example during post-surgical or post-traumatic healing or in the evaluation of the efficacy of topical therapeutic agents.
Animals↗