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Biomedical subjects

J T Fan

Publications and source records attributed to J T Fan.

11 recordsLinked to original sources
PubMed2001

Brimonidine 0.2% versus apraclonidine 0.5% for prevention of intraocular pressure elevations after anterior segment laser surgery.

OBJECTIVE: To compare the efficacy of brimonidine 0.2% with apraclonidine 0.5% in preventing intraocular pressure (IOP) elevations after anterior segment laser surgery. DESIGN: Double-masked, randomized clinical trial. PARTICIPANTS: Sixty-six patients underwent either laser peripheral iridotomy, argon laser trabeculoplasty, or neodymium:yttrium-aluminum-garnet laser capsulotomy. INTERVENTION: Eyes received either one drop of brimonidine 0.2% or apraclonidine 0.5% before laser surgery. MAIN OUTCOME MEASURES: Intraocular pressure, heart rate, and blood pressure were measured before laser surgery and at 1 hour, 3 hours, 24 hours, and 1 week after laser surgery. RESULTS: Before the laser treatment, 33 patients (50.0%) received brimonidine 0.2% and 33 patients (50.0%) received apraclonidine 0.5%. Eight of 33 patients (24.2%) in the brimonidine-treated group and 9 of 33 patients (27.3%) in the apraclonidine group had postoperative IOP increases of 5 mmHg or more. This was not statistically different (P = 0.80). By the time of last follow-up examination, 3 of 33 patients (9.1%) in the brimonidine-treated group and 3 of 33 patients (9.1%) in the apraclonidine group had IOP increases of 10 mmHg or more. This was also not statistically different (P > or = 0.95). The mean IOP reduction from baseline in the brimonidine group (-2.8 +/- 2.8 mmHg) was not statistically different (P = 0.55) compared with the mean IOP reduction in the apraclonidine group (-3.6 +/- 3.3 mmHg). There were no statistically significant changes in mean heart rate or blood pressure in either group except for a slight reduction in diastolic blood pressure at 1 hour (P = 0.005) in the brimonidine group (-5.2 +/- 7.4 mmHg) compared with the apraclonidine group (-0.2 +/- 6.4 mmHg). There were no clinically significant side effects noted in either group. CONCLUSIONS: A single preoperative drop of brimonidine 0.2% is as effective as apraclonidine 0.5% in preventing IOP elevation immediately after anterior segment laser surgery.

Adrenergic alpha-Agonists↗
PubMed1999

The relationships of age changes in retinal pigment epithelium and Bruch's membrane.

PURPOSE: To study the correlations between age, Bruch's membrane (BM) thickness, retinal pigment epithelial (RPE) autofluorescence, and RPE residual body content. METHODS: Eight-millimeter-diameter macular discs from 88 unpaired human eye bank eyes were obtained within 72 hours of death, fixed in 10% neutral buffered formalin, and hemisected horizontally. One portion of the macular disc was embedded in paraffin and stained with periodic acid-Schiff for the measurement of BM thickness. RPE autofluorescence measurements were performed on unstained, deparaffinized sections. A second portion of the macular disc was prepared for electron microscopy to evaluate RPE residual body content. Linear and polynomial regression techniques were used to investigate the correlations between age, BM thickness, RPE autofluorescence, and RPE residual body content. RESULTS: Bruch's membrane thickness increased with age according to the linear model. RPE autofluorescence and RPE residual body content also increased with age, but the correlations were best approximated by a quadratic model. The correlations between RPE autofluorescence and residual body content and between BM thickness and RPE autofluorescence were best approximated by a linear regression model. There was considerable variation in these correlations between specimens and within the same age group. CONCLUSIONS: Although the changes in RPE and Bruch's membrane increased with age and there was a direct correlation between changes in the two tissues, there was considerable variation within each age group and between specimens. This probably reflects the multifactorial nature of the process.

Adolescent↗
PubMed1995

Clinical features and treatment of seven patients with carcinoid tumor metastatic to the eye and orbit.

PURPOSE: To understand better the clinical features, treatment, and outcome of patients with carcinoid tumors metastatic to the eye and orbit. METHODS: We studied seven patients with carcinoid tumors metastatic to the eye and orbit who were initially examined at the Mayo Clinic between 1974 and 1992. Carcinoid tumors metastasized to the choroid of six eyes of four patients and unilaterally to the orbit in three additional patients. RESULTS: Decreased vision was the most frequent initial symptom with choroidal metastases. Choroidal metastases were treated with brachytherapy only, with brachytherapy and chemotherapy, with external beam irradiation and chemotherapy, or with chemotherapy only. The duration of follow-up of these four patients ranged from seven to eight years after the diagnosis of choroidal metastases. Two of the four patients died from tumor complications 7 1/2 and seven years after the diagnosis of choroidal metastases. Proptosis and limitation of ocular motility were the most common initial signs with orbital metastases. Orbital metastases were treated with external beam irradiation and chemotherapy, with chemotherapy only, or with external beam irradiation only. Duration of follow-up of these three patients ranged from one-half to two years after the diagnosis of orbital metastases. All three patients died from tumor complications during the follow-up period. CONCLUSIONS: Because of the relatively good prospects for long-term survival in patients with carcinoid tumors metastatic to the choroid, early detection and treatment of the metastases are important.

Aged↗
PubMed1995

Clinicopathologic correlation of a case of adenocarcinoma of the retinal pigment epithelium.

PURPOSE/METHODS: We observed a clinicopathologic correlation of a case of adenocarcinoma of the retinal pigment epithelium. RESULTS/CONCLUSIONS: The ultrasonographic findings of this tumor demonstrated a collar button profile with high internal reflectivity. The ultrasonographic characteristics in this case reflected the variable vascularity and cystic spaces within the tumor.

Adenocarcinoma↗
PubMed1995

Long-term follow-up of the Allen implant. 1967 to 1991.

PURPOSE: The objectives of this study are to determine the incidence of superficial tissue breakdown and/or exposure of the Allen implant, to identify potential risk factors for superficial tissue breakdown and/or exposure of the Allen implant, and to provide a comparison for future studies of other orbital implants. METHODS: The authors retrospectively studied 186 consecutive patients managed with enucleation and Allen implant placement from January 1967 through December 1991. Information was obtained from a review of the patients' records and from telephone and letter surveys. RESULTS: More than half of the patients had follow-up more than 5 years and approximately one third had follow-up of 10 or more years. The mean length of follow-up was 7.8 years. Two allen implants (1.1%) became exposed 5.3 and 11.5 years, respectively, after initial implant placement and were subsequently replaced by dermis fat grafts. Superficial tissue breakdown without implant exposure occurred over four additional Allen implants (2.2%); the patients satisfactorily were treated medically or surgically without the need for removal or replacement of the Allen implant. Most prostheses have horizontal and vertical excursions of 30 degrees or more. CONCLUSION: The satisfactory motility, the low incidence of superficial tissue breakdown, and the even lower incidence of exposed Allen implants observed in our long-term follow-up study provide evidence that the Allen implant is a satisfactory choice to replace the enucleated eye. The absence of implant exposure occurring before 5 years of follow-up underscores the need for long-term follow-up to properly evaluate newer orbital implants.

Adolescent↗
PubMed1991

Donor cornea bacterial contamination.

The incidence of culture-positive cornea rims from 446 consecutive donor corneas cultured at the Doheny Eye Institute between 1986 and 1988 was determined. Both the identity and antibiotic sensitivities of the contaminating organisms were reviewed. Sixty-three (14.1%) of 446 cornea rims were culture-positive, but none of the 63 patients who received these contaminated donor corneas developed endophthalmitis. Streptococcus (26 of 63), Propionibacterium (15 of 63), Stphylococcus (14 of 63) species and diptheroids (8 of 63) were the most common cornea rim contaminants, and in most cases were resistant to gentamicin (i.e., 21 of 26 or 81%, 9 of 15 or 60%, 10 of 14 or 71%, 4 of 8 or 50%, respectively). Virtually all of the gentamicin-resistant bacteria isolated from cornea rims were found to be sensitive to vancomycin. Eye banks should consider the addition of other antibiotics to storage media to reduce donor cornea contamination. Surgeons performing corneal transplantation should also consider these results when selecting antibiotics for use at the time of surgery and in the postoperative period.

Anti-Bacterial Agents↗
PubMedDate not supplied

Immunologic responses in experimental cytomegalovirus labyrinthitis.

To better understand the pathogenesis of cytomegalovirus labyrinthitis, a guinea pig model was created. Following inoculation at several sites (cardiac, perilymph, and endolymphatic sac) in both seronegative and seropositive animals, the immunologic, histologic, and electrophysiologic responses were measured. Seronegative animals uniformly showed progressive hearing loss with marked inflammation and degeneration of neural elements. In animals inoculated into the endolymphatic sac, an associated endolymphatic hydrops developed in addition to deafness. Seropositivity protected the hearing, but endolymphatic sac inoculations resulted in mild hydrops due to local inflammation that was devoid of evidence of viral replication. The question of whether hearing loss was attributable to local inflammatory responses rather than the cytopathic effects of the virus was then examined. To test this hypothesis, animals were immunosuppressed with cyclophosphamide prior to intracochlear inoculation of cytomegalovirus. The immunosuppressed animals showed significantly better hearing than the controls, and this correlated directly with the degree of cellular infiltration of the scala tympani. These studies confirm the importance of host immune responses in the pathogenesis of hearing loss due to cytomegalovirus.

Animals↗