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Biomedical subjects

R K Forster

Publications and source records attributed to R K Forster.

At least 19 recordsLinked to original sources

Determinants of graft clarity in penetrating kerotoplasty.

A total of 240 consecutive penetrating keratoplasties with a minimum six months' follow-up were examined to determine the influence of preoperative prognosis, donor age, death-enucleation time, death-surgery time, and surgical experience on graft clarity. Graft results, classified as clear, nebulous, or edematous, were compared within two prognostic categories in aphakic, combined, and phakic keratoplasty groups. Preoperative prognostic groups and surgical experience appeared to be most important in affecting graft clarity, whereas the donor age, death-enucleation time, and death-surgery time seemed to have little effect.

Age Factors

Clinical specular microscopy and intraocular surgery.

Seventy patients were studied prospectively, using the clinical specular microscope, to compare and evaluate the effects on the corneal endothelium of routine intracapsular cataract extraction (ICCE), ICCE with intraocular lens (IOL) implantation, phacoemulsification, and penetrating keratoplasty. Results showed a 6% cell loss after ICCE, 12% loss after IOL insertion, 14% after phacoemulsification, and 21% loss after penetrating keratoplasty. Both phakic and aphakic grafts had 21% cell loss. Within the aphakic keratoplasty group, there was a 10% cell loss in patients who maintained an intact vitreous face compared with a 26% cell loss in patients who underwent an anterior vitrectomy (P less than .1).

Adult

Superficial punctate keratitis of Thygeson associated with scarring and Salzmann's nodular degeneration.

A 59-year-old woman with superficial punctate keratitis of Thygeson was observed for 14 years. The patient was treated intermittently with topical corticosteroids and artificial tears. Immediate symptomatic relief was followed by multiple recurrences and exacerbations. This case was atypical because of its prolonged clinical course and development of permanent, subepithelial corneal scarring, and elevated lesions resembling Salzmann's nodular degeneration.

Administration, Topical

Diagnostic limulus lysate assay for endophthalmitis and keratitis.

The limulus lysate assay is an inexpensive, reliable, and rapid means of detecting and presence of Gram-negative endotoxin. In all ten cases of experimentally induced Proteus endophthalmitis in rabbits, the assay was positive, and the assay was appropriately negative in all ten cases of Staphylococcal endophthalmitis, ten cases of Candida endophthalmitis, and ten cases of sterile endophthalmitis in rabbits. In a clinical assessment of keratitis, the assay of corneal scrapings was positive in 11 of 13 Gram-negative corneal ulcers. In a similar study of clinical endophthalmitis, both Gram-negative cases had a negative limulus assay, but two cases are insufficient to be conclusive. The assay may prove to be a useful adjunct both to standard diagnostic evaluations and in the rapid direction of appropriate therapy for these conditions.

Animals

Listeria monocytogenes endophthalmitis with a black hypopyon.

A 68-year-old woman had a marked decrease in visual acuity, increased intraocular pressure, and acute iridocyclitis. She developed a pigmented hypopyon simulating an occult intraocular melanoma. Two anterior chamber paracenteses showed growth of Listeria monocytogenes. The patient received systemic intravenous penicillin, topical fortified gentamicin sulfate drops, and intraocular injections of cephaloridine. On discharge from the hospital after a two-week stay, visual acuity had improved and intraocular pressure had decreased.

Aged

Etiology and diagnosis of bacterial postoperative endophthalmitis.

It is necessary to determine if postoperative endophthalmitis is of infectious or sterile etiology. Intraocular contents should be cultured and were positive in 50% of 58 eyes tested at our institute with suspected postoperative endophthalmitis. The vitreous aspirate is more sensitive than the anterior chamber aspirate in making a diagnosis. The use of a membrane filter to concentrate vitreous samples obtained at vitrectomy increases diagnostic yield. Fifty percent of culture-positive eyes yielded gram-positive organisms. Stained smears were consistent with the cultured organism in half of the cases.

Anterior Chamber

Intravitreal antimycotic therapy and the cure of mycotic endophthalmitis caused by a Paecilomyces lilacinus contaminated pseudophakos.

A salvaged eye in a case of mycotic endophthalmitis is reported. The case was one of eleven in the United States resulting from Luminex lens implants contaminated with amphotericin B resistant Paecilomyces lilacinus, and one of two eyes salvaged in this series of cases. The fungus, recognized 28 days after the lens was inserted, was in the anterior chamber, on the psuedophakos, and in the vitreous. The therapeutic procedures included removal of the pseudophakos, radical vitrectomy and iridectomy, and the intraocular and combined topical and systemic use of antimycotic compounds, including miconazole and thiabendazole.

Aged

Vitrectomy in endophthalmitis. Results of study using vitrectomy, intraocular antibiotics, or a combination of both.

A rabbit model of endophthalmitis was produced by inoculating Staphylococcus epidermidis and S aureus into the vitreous cavity. Elimination of microorganisms was compared using intravitreal administration of 0.1 mg of gentamicin alone, vitrectomy alone, and a combination of gentamicin and vitrectomy. In the case of S. epidermidis treated 24 hours after inoculation, all untreated eyes were culture-positive at one week, eyes treated with gentamicin alone or intravitreal gentamicin in combination with vitrectomy were all culture-negative, and vitrectomy alone rendered half of the eyes culture-negative. In the case of S aureus, eyes not treated by vitrectomy alone were all culture-positive at one week. Eyes treated with intravitreal gentamicin 25 to 31 hours after infection were culture-negative for S aireus in 33% at one week, while eyes treated with combined vitrectomy plus intraocular gentamicin were culture-negative in 83% of cases. When treatment was delayed 40 to 49 hours after inoculation of S aureus, intravitreal rendered 50% culture-negative at one week, while vitrectomy combined with intravitreal gentamicin eliminated the infection in 100% of eyes.

Animals

Further observations on the diagnosis cause, and treatment of endophthalmitis.

In our study of 54 suspected cases of endophthalmitis, vitreous aspiration was more sensitive in making a culture-proven diagnosis than anterior chamber paracentesis; Staphylococcus epidermidis was a more common cause of endophthalmitis than previously appreciated; and intraocular antibiotics in the recommended dosage are reasonably safe clinically and add a new dimension to the treatment of endophthalmitis.

Anterior Chamber

Experimental intravitreal gentamicin.

Rabbits received intravitreal injections of gentamicin and indirect ophthalmoscopy, electroretinography, and histopathology determined relative toxicity. An intravitreal dose of 0.1 to 0.2 mg of commercially available gentamicin was well tolerated in the rabbit eye. A dosage of 0.4 mg or higher consistently produced significant ocular toxicity as evidenced by extinction of the electroretinogram, gross fundus changes, and histopathologic alterations.

Animals

Lasiodiplodia theobromae as a cause of keratomycoses.

Four cases of human keratitis caused by the tropical fungus Lasiodiplodia theobromae have been encountered in Miami, Florida bringing to 8 the number of cases reported in the world literature. Two of the ulcers were mild. Three patients recovered without severe impairment of vision after topical polyene treatment, but 1 patient with a severe ulcer required therapeutic keratoplasty after 11 days of topical natamycin. Histopathology revealed fungus deep in the cornea, invading Descemet's membrane. L. theobromae appeared to have collagenase activity in vitro. Inoculation of L. theobromae into the corneas of rabbits produced progressive ulcers. The fungus was endemic in Miami on home grown and imported bananas. Polyene antimycotic antibiotics were fungicidal for L. theobromae in vitro. Thiabendazole was effectively fungistatic but varied in fungicidal effect. Clotrimazole and miconazole were only incompletely fungistatic. Of 7 strains of L. theobromae tested, 4 were relatively resistant to 5-flurocytosine.

Adolescent

Laser iridotomy for aphakic pupillary block.

In six patients with aphakic pupillary block, argon laser produced full-thickness iridotomies that succeeded in restoring anterior chamber and intraocular pressure to normal. In one case, it was shown that location of iridotomy is important in determining whether or not iridotomy will succeed in relieving aphakic pupillary block. In two cases, pupillary block had resulted in shallowing of the anterior chamber without pressure elevation. Cases reported here show that continuous laser energy, such as from an argon laser, can produce a full-thickness opening, in contrast to the short duration pulse of the ruby, which will destroy only pigmented structures without producing a full-thickness iris opening. This need to produce some degree of spread of damage to unpigmented tissue elements in order to achieve and iris opening is a problem in phakic patients where injury to the lens must be avoided.

Aged

Comparison of MacKay-Marg, Goldmann, and Perkins tonometers in abnormal corneas.

Intraocular pressure was determined manometrically in owl monkey eyes with normal and edematous corneas. The pressure was measured with Perkins hand-held, Goldmann, and MacKay-Marg tonometers to compare relative accuracy. At monometric levels of 20, 30, and 40 mm Hg, a statistically significant difference in readings was found between normal and edematous corneas with use of the Perkins and Goldmann applanators, whereas no such difference was found with the MacKay-Marg tonometer. The MacKay-Marg tonometer most closely approximated the true intraocular pressure in edematous corneas.

Animals

The diagnosis and management of keratomycoses. II. Medical and surgical management.

Medical management of 61 cases of mycotic keratitis, including the use of natamycin (pimaricine) in 53 cases, resulted in successful healing in 46 cases. A final visual acuity of 20/40 or better was achieved in 25 cases by medical therapy alone. Thirteen cases were considered medical treatment failures, and 11 necessitated therapeutic surgery. A final visual acuity of 20/70 or better was achieved in six of these cases, including five of nine therapeutic penetrating keratoplasties. In four cases, ulceration had progressed despite natamycin treatment, but fungal cultures were negative at the time of therapeutic surgery.

Anti-Bacterial Agents

Recurrent keratitis due to Acremonium potronii.

In a 15-year-old boy a culture-proved keratitis after a corneal perforation healed without antifungal agents after corneal suturing and application of tissue glue. Eight months later a posterior corneal abscess developed. Diagnostic and therapeutic penetrating keratoplasty was performed when the lesion failed to respond to pimaricin. Cultures were positive for Acremonium potronii, the same fungus isolated from the original corneal laceration eight months previously. To our acknowledge, this is the first case report of a central corneal ulcer or abscess due to this specific organism.

Adolescent

Animal model of Fusarium solani keratitis.

Because of the frequency of fungal keratitis due to Fusarium solani, we needed a sustained, progressive infection in an animal model to determine the mechanisms of pathogenicity and to evaluate the new antifungal agents. Pigmented rabbits interlamellarly injected with actively germinating conidia from lyophilized temperature-tolerant strains of F. solani produced sustained culture-positive ulcers in high percentage of eyes at two and three weeks, pretreatment with subconjunctival corticosteroids was necessary. Histopathology, although a poor index of infectivity since some corneas with plentiful hyphal fragments had negative cultures, simulated human fungal pathology.

Animals

Therapeutic surgery in failures of medical treatment for fungal keratitis.

Medical treatment failure necessitated surgery in nine cases of fungal keratitis. Therapeutic surgery eliminated fungal infection in seven cases, and useful vision was retained in five out of six penetrating keratoplasties. In three cases Natamycin (Pimaricin) therapy rendered fungi non-viable, but two were demonstrable by histopathology. These results suggest that antifungal treatment should be applied for as long as possible before therapeutic surgery in order to improve the final visual outcome.

Conjunctiva