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Biomedical subjects

P H Choo

Publications and source records attributed to P H Choo.

12 recordsLinked to original sources
PubMed2001

Lower eyelid CO(2) laser rejuvenation: a randomized, prospective clinical study.

PURPOSE: The effect of transconjunctival blepharoplasty alone compared with transconjunctival blepharoplasty and CO(2) laser skin resurfacing on lower lid bulging and wrinkles was examined. DESIGN: Randomized clinical trial. PARTICIPANTS: Forty-four subjects, including 13 men and 31 women. METHODS: Subjects were prospectively randomly assigned into two groups: (1) transconjunctival blepharoplasty with immediate CO(2) laser resurfacing or (2) transconjunctival blepharoplasty with CO(2) laser resurfacing 2 months later. Standardized photographs were taken before and 2 months after each procedure. A trained, masked observer graded the photographs. MAIN OUTCOME MEASURES: Bulging and wrinkles of the medial, central, and lateral portions of the lower lid were scored and compared at specified end points. RESULTS: Transconjunctival blepharoplasty alone resulted in an improvement in lower lid bulging in 92% of subjects, whereas lower lid wrinkling worsened in 46%. When transconjunctival blepharoplasty was performed with simultaneous CO(2) laser resurfacing, or with CO(2) laser resurfacing 2 months later, a statistically significant improvement in wrinkles occurred (chi square = 20.625; P < 0.0005). The timing of the procedures had no statistically significant effect on final outcome. No subject had lower lid retraction develop. CONCLUSIONS: Transconjunctival blepharoplasty and adjunctive CO(2) laser resurfacing represents an excellent alternative to transcutaneous lower blepharoplasty. The procedure addresses lower lid wrinkles, skin redundancy, and fat herniation without a scar and with little risk of lower lid retraction.

Blepharoplasty↗
PubMed2001

Lasers in oculoplastics.

In the past year, there have been many important advances in laser application in not only oculoplastics but also related fields such as dermatology and plastic surgery. This review article highlights advances in laser assisted lacrimal surgery with the adjunctive use of mitomycin C and the treatment of capillary hemangiomata with a tunable dye laser. There also have been advances in laser skin resurfacing, such as the combination of carbon dioxide and erbium:yttrium-aluminum-garnet lasers to achieve improved results as well as the use of nonablative lasers. Lastly, physicians have achieved a greater understanding of the benefits and complications of combining laser resurfacing with other aesthetic procedures, such as lower blepharoplasty and facelifting.

Eye Diseases↗
PubMed2000

Modified orbital decompression for dysthyroid orbitopathy.

PURPOSE: The transantral approach to orbital decompression remains useful for the management of exophthalmos associated with dysthyroid orbitopathy. However, the risk of postoperative diplopia is a concern. Preservation of the anterior periorbita may help support the orbital contents and decrease the incidence of diplopia. METHODS: The medical records were reviewed of 15 consecutive patients who underwent 30 transantral orbital decompressions for proptosis associated with dysthyroid orbitopathy. The procedures were completed in standard fashion, including removal of the inferomedial bony strut between the medial orbital wall and the floor. However, stripping of the periorbita was only done posteriorly; the anterior 10 to 15 mm of periorbita were left intact. RESULTS: Six patients had preoperative diplopia that persisted after decompression. Of the nine patients without diplopia preoperatively, none developed diplopia. Proptosis was reduced a mean of 3.5 +/- 2.6 mm. CONCLUSIONS: Preservation of the anterior periorbita during transantral orbital decompression reduces the risk of postoperative diplopia. An adequate reduction in proptosis is also achieved.

Adolescent↗
PubMed2000

Upper eyelid gold weight implantation in the Asian patient with facial paralysis.

Patients with facial paralysis may develop ophthalmic complications. Poor eyelid closure and lagophthalmos place the patient at increased risk for the development of corneal problems such as epithelial defects, stromal thinning, bacterial infection, and even perforation. Initial treatment should be conservative and include the use of ocular lubricants, moisture chambers, and taping of the lower eyelid into proper position. Surgical intervention may be required in patients who have failed medical therapy or in whom the facial paralysis is not expected to improve. Gold weight implantation in the upper eyelid has become a popular procedure to correct upper eyelid retraction and to improve corneal coverage. Previous descriptions of gold weight placement in the upper eyelid have focused on Caucasian eyelid anatomy. However, there are distinct anatomic differences between the Caucasian and Asian eyelids, which dictate the overlying aesthetic differences. We describe our technique for placement of a gold weight in the Asian upper lid, with attention to the maintenance of symmetric eyelid creases. We reviewed the charts of six Asian patients with facial paralysis who underwent gold weight placement in the upper eyelid for the correction of lid retraction. All patients did well functionally and aesthetically, and none developed an extrusion of the implant with this approach.

Adult↗
PubMed1999

Tarsal margin rotation with posterior lamella superadvancement for the management of cicatricial entropion of the upper eyelid.

PURPOSE: To report the efficacy of tarsal margin rotation with posterior lamella superadvancement in the management of cicatricial entropion of the upper eyelid. METHODS: In 15 consecutive patients, 22 eyelids with cicatricial entropion were managed with tarsal margin rotation and posterior lamella superadvancement. In a retrospective study, the technique and results were evaluated. RESULTS: In all 22 upper eyelids, the normal eyelashes rotated away from the surface of the eye. Mean follow-up was 12.9 +/- 12.4 months (range, 1 to 48 months). One eyelid developed buckling of the tarsus. Three eyelids needed electrolysis to treat isolated metaplastic cilia posterior to the normal lash line. CONCLUSIONS: Tarsal margin rotation with posterior lamella superadvancement appears to be effective in managing cicatricial entropion of the upper lid.

Adolescent↗
PubMed1999

Role of local amphotericin B therapy for sino-orbital fungal infections.

PURPOSE: Sino-orbital fungal infections are serious complications of diabetes and immunosuppression. Standard treatments include surgical debridement of the involved tissues with possible orbital exenteration, intravenous antifungal therapy, and improvement of the host's immunocompetence and metabolic state, when possible. The role of conservative orbital debridement combined with local amphotericin B irrigations in the treatment of these patients was evaluated. METHODS: The records of seven consecutive patients with sino-orbital fungal infections, who were treated with limited surgical debridement and local and systemic amphotericin B therapy, were reviewed. The underlying disorders of these patients included acute lymphoblastic leukemia, immunosuppression after renal transplantation, diabetes mellitus, and acquired immunodeficiency syndrome. The fungal species identified included Rhizopus, Mucor, and Aspergillus. RESULTS: Follow-up ranged from 4 months to 4 years. All patients retained their preoperative visual acuities. Only one patient ultimately underwent an orbital exenteration for progressive orbital fungal infection. The remaining patients had either complete or incomplete (without further progression) resolution of their fungal infection. Two of the seven patients died of unrelated causes, and no patient died of uncontrolled fungal spread. CONCLUSIONS: Conservative orbital debridement with local amphotericin B irrigations is an effective adjunct in the control of sino-orbital fungal infections, especially in patients with reversible immunosuppression and good preoperative visual acuities.

Adult↗
PubMed1999

Exposure of expanded polytetrafluoroethylene-wrapped hydroxyapatite orbital implant: a report of two patients.

PURPOSE: Hydroxyapatite (HA) spheres used to replace volume after an enucleation are often wrapped with autologous tissue before orbital implantation. Man-made materials are less expensive and pose no risk for viral transmission. The use of expanded polytetrafluoroethylene (ePTFE) to wrap HA spheres was evaluated. METHODS: The medical records of 2 consecutive patients who underwent uncomplicated implantation of an HA sphere wrapped in ePTFE were reviewed. RESULTS: An unusual reaction to the ePTFE material that was nonresponsive to topical or systemic antibiotic therapy developed in these 2 patients. Eventual wound erosion and bacterial infection of the implant necessitated its removal. CONCLUSIONS: Although well tolerated in other surgeries, ePTFE, when used to wrap HA spheres and placed into the orbit, may cause persistent conjunctival discharge, pyogenic granuloma formation, and eventual wound erosion. Therefore, the use of this material to wrap HA spheres is not recommended.

Aged↗
PubMed1991

Inhibition of rabbit ocular fibroblast proliferation by 5-fluorouracil and cytosine arabinoside.

Inhibition of rabbit subconjunctival fibroblast attachment and proliferation by the antimetabolites 5-fluorouracil (5-FU) and cytosine arabinoside (ara-C) was determined by radionucleotide uptake, cell counting, and colorimetric assays for the concentration range of 1000 to 0.0001 micrograms/ml over an 11-day period. The mean 50% inhibitory doses (ID50s) against proliferation were calculated for each assay. Rabbit fibroblast attachment was not inhibited at any drug concentration by either 5-FU or ara-C. Ara-C was a 10 to 100 times more potent inhibitor of rabbit fibroblast proliferation than 5-FU. The mean ID50s for rabbit subconjunctival fibroblasts were compared with the mean ID50s from a similar series of experiments conducted in our laboratory on human subconjunctival fibroblasts. Unpaired t-test analysis showed a significant difference between the inhibitory effects of 5-FU on rabbit and human fibroblast proliferation. An ID50 against rabbit fibroblasts was detectable after 24 hours of incubation with 5-FU by the 3H-thymidine uptake assay, whereas the ID50 against human fibroblasts was detectable after 48 hours of incubation. Once inhibition of proliferation occurred, however, human fibroblasts were up to six times more sensitive to the antiproliferative effects of 5-FU than rabbit fibroblasts as measured by the 3H-thymidine uptake assay (p = 0.0005). Unpaired t-test analysis showed no statistical difference between the ID50s of ara-C on rabbit and human fibroblasts. Starting on day 3, however, doses greater than 1 micrograms/ml of ara-C were cytotoxic to rabbit fibroblasts but only cytostatic to human fibroblasts as determined by trypan blue uptake assay microscopically. Rabbit ocular fibroblasts may be useful in modelling the proliferation of human ocular fibroblasts in vitro to a limited degree. This tissue culture system may be useful for predicting optimal drug dosages for in vivo rabbit and human glaucoma filtering surgery.

Animals↗
PubMed1990

Adrenal steroid type I and type II receptor binding: estimates of in vivo receptor number, occupancy, and activation with varying level of steroid.

Adrenal steroid (AS) receptors differ from other steroid receptors in the inability of the activated form of the cytosolic receptor to exchange ligand in an in vitro binding assay. We extended this finding by demonstrating that AS receptors extracted from isolated brain nuclei also failed to exchange ligand. Taking advantage of this unique feature of AS receptors, we measured type I and type II AS binding level in rats with varying amounts of endogenous glucocorticoids or exogenous dexamethasone (DEX). We estimated the degree of receptor occupation/activation in various brain areas and the pituitary during basal glucocorticoid conditions and after acute stress. There was a variable proportion of type I receptors in the hippocampus which were unactivated during basal conditions (0-35%). The proportion of unactivated type I receptors increased (55-65%) after DEX treatment. The hippocampus was especially sensitive to the ability of low basal corticosterone (CORT) levels to activate both type I and type II receptors, whereas the pituitary was very insensitive, evidenced by a failure of acute stress levels of endogenous glucocorticoids to occupy/activate type II receptors in the pituitary. Comparison of estimates of the degree of in vivo hippocampal type I and type II receptor activation for the various treatment groups with estimates of in vitro type I and type II receptor occupation by steroid suggested that DEX was more efficient than CORT in producing or maintaining the activated form of the type II receptor in vivo, whereas CORT was more efficient than DEX in activating the type I receptor. These studies suggest that AS receptors in the brain, and especially the hippocampus, are more sensitive to circulating levels of glucocorticoids than the pituitary. There also may be a greater capacity for physiological variations in type I receptor occupation in vivo than had previously been suggested. Finally, discrepancies between CORT and DEX affinity in vitro for type I and type II sites and their in vivo potency may be accounted for by differences in the ability of these compounds to activate type I and type II AS receptors.

Animals↗
PubMed1989

Glucocorticoid and mineralocorticoid receptor mRNA expression in rat brain.

In the rat brain, the binding of corticosterone is mediated through two receptor types, the type I receptor and the type II receptor, which are presumed to be encoded by genes designated as MR and GR, respectively. We have studied the regulation of these receptors by glucocorticoids, utilizing a cytosol receptor binding assay. In addition, we have employed molecular probes for the GR and the MR to measure receptor mRNAs. The level of type II receptor binding is uniform across several brain regions, as is the expression of GR (type II) mRNA. In contrast, type I receptor binding is concentrated in the hippocampus, and the MR (type I) mRNA similarly shows a higher level of expression in hippocampus than in the other brain regions studied. Removal of endogenous glucocorticoids by adrenalectomy (ADX) induces an increase, and corticosterone administration results in a decrease, in the level of type I and type II binding in the hippocampus; however, no significant changes in the MR (type I) or GR (type II) mRNA levels are seen with these treatments. The diurnal variation of serum corticosterone in intact rats is correlated with a circadian regulation of type I receptor binding in the hippocampus, while MR (type I) mRNA expression is unaffected. Thus, the changes in type I and type II receptor binding capacity elicited by differing steroid conditions cannot be attributed to modulation of the steady state levels of MR (type I) or GR (type II) mRNA.

Animals↗