Biomedical subjects

Viet Bui

Publications and source records attributed to Viet Bui.

4 recordsLinked to original sources

PubMed2006

Wound-healing response and refractive regression after conductive keratoplasty.

PURPOSE: To characterize the histological changes that occur after conductive keratoplasty (CK) using a rabbit model. SETTING: LSU Eye Center and Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, School of Medicine, New Orleans, Louisiana, USA. METHODS: Conductive keratoplasty was performed on 24 eyes of 12 New Zealand albino rabbits. In each eye, 24 spots were placed in a cross-corneal manner using 3 optical zones at 6.0, 7.0, and 8.0 mm. Eyes were assessed with corneal topography weekly. Rabbits were humanely killed 2, 4, 6, and 8 weeks postoperatively. The eyes were then enucleated and processed for histopathology and immunohistochemical analysis. RESULTS: All eyes showed an initial mean steepening of the corneal curvature of 2.24 diopters (D) 2 weeks postoperatively. Corneal topography revealed a 26%, 36%, and 39% regression of the refractive results at 4, 6, and 8 weeks, respectively. Immunohistochemical analysis demonstrated keratocyte apoptosis, myofibroblast appearance, and upregulation of chondroitin sulfate, MMP-1, and collagen III in the area surrounding the tip in each spot. CONCLUSION: The histological changes that occur after CK may be responsible for the well-established regression of its refractive effect. A better understanding of the wound-healing response after CK is necessary to improve the long-term stability of the procedure.

Actins↗

PubMed2005

Topical combination of NGF and DHA increases rabbit corneal nerve regeneration after photorefractive keratectomy.

PURPOSE: To investigate the effect of nerve growth factor (NGF) in combination with docosahexaenoic acid (DHA) on corneal nerve regeneration in a rabbit model after PRK and correlate the findings with functional tear test. METHODS: Unilateral PRK was performed on 21 New Zealand albino rabbits. Three groups, each consisting of six rabbits, were randomized to receive twice-weekly treatments with DHA, NGF, or NGF plus DHA delivered by collagen shield. A fourth group, the control, received treatment with albumin. Rabbits were observed for 8 weeks, and tear secretion tests were conducted every 15 days. The eyes were prepared for immunostaining. Monoclonal antibodies for class II beta-tubulin, calcitonin gene-related peptide (CGRP), substance P (SP), and Ki-67 were used. Cell nuclei were stained with 4',6'-diamino-2-phenylindole (DAPI). Positive staining areas in relation to total area were calculated with image-analysis software. RESULTS: There were no significant differences in the tear-secretion test results among the four groups. However, none of the eyes treated with NGF plus DHA showed rose bengal staining 30 days after PRK, compared with 50% in the control group and 33% in the DHA-treated group. A higher percentage of Ki-67-positive cells, a marker of cell proliferation, was observed in the DHA plus NGF-and NGF-treated groups compared with DHA alone or the control. Eight weeks after PRK, tubulin-positive and CGRP-positive epithelial and subbasal nerve bundle areas were significantly higher in the DHA plus NGF group than in the control and NGF or DHA alone. No differences were noted in the SP-positive nerve bundles between the different treatments and the control treatment. CONCLUSIONS: NGF plus DHA treatment after PRK in rabbits is associated with increased corneal nerve surface area, increased epithelial proliferation, and decreased rose bengal staining compared with NGF, DHA, or vehicle control alone. The combination of NGF plus DHA yields faster nerve recovery after PRK and may have therapeutic usefulness in the treatment of post-PRK dry eye and other neurotrophic keratopathies.

Administration, Topical↗

PubMedDate not supplied

Surgical correction of hyperopia.

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.

Corneal Surgery, Laser↗

PubMedDate not supplied

Long-term refractive results of myopic LASIK complicated with intraoperative epithelial defects.

PURPOSE: To evaluate the long-term refractive results of LASIK for myopia complicated with intraoperative epithelial defects. METHODS: Twenty-six eyes with epithelial defects on the LASIK flap were compared with the contralateral eye that had no intraoperative complications. Pre- and postoperative data were compared between the two groups including 3-, 6- and 12-month postoperative spherical equivalent refraction, amount of undercorrection, and complications. RESULTS: Eyes with intraoperative epithelial defects showed more undercorrection at 3 and 6 months postoperatively (P < .05). No statistically significant difference was noted at 12 months. Twenty (76%) eyes in the epithelial defect group lost best spectacle-corrected visual acuity (BSCVA) at 3 months postoperatively compared with 2 (7%) eyes in the control group. By 1 year, however, only 2 (7%) eyes in the epithelial defect group and no eyes in the control group lost > 1 line of BSCVA. Diffuse lamellar keratitis was observed in 15 (58%) of 26 eyes with epithelial defects and these eyes had more undercorrections at 6 and 12 months (P < .05) and higher corneal irregularity index at 6 and 12 months compared with controls (P < .05). Eyes with small epithelial defects (> 1 mm2 to < 3 mm2) had more undercorrections at 6 months (-1.08 +/- 0.76 diopters [D]) compared with the control group (-0.46 +/- 0.87 D). Eyes with centrally located epithelial defects had more undercorrections and increased corneal irregularity index compared with controls (P < .05). CONCLUSIONS: Intraoperative epithelial defects after LASIK should be considered a severe complication that may result in diffuse lamellar keratitis, induce loss of BSCVA, prolong recovery of visual acuity, and induce undercorrection.

Adult↗