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Biomedical subjects

D S Fan

Publications and source records attributed to D S Fan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Truncations in the TIGR gene in individuals with and without primary open-angle glaucoma.

PURPOSE: To investigate the coding exons in the trabecular meshwork-induced glucocorticoid response protein (TIGR) gene for mutations in primary open-angle glaucoma (POAG) in Chinese subjects. METHODS: Ninety-one Chinese patients with POAG and 113 of their family members without glaucoma were screened for sequence alterations in the TIGR gene by polymerase chain reaction, conformation-sensitive gel electrophoresis, and DNA sequencing. One hundred thirty-two unrelated individuals without glaucoma, aged 50 years or more, were studied as control subjects. RESULTS: Five sequence variants that lead to amino acid changes were identified. One was novel: Arg91Stop in one patient with POAG. Four had been reported: Arg46Stop in subjects with and without POAG, including an unaffected 77-year-old woman homozygous for Arg46Stop; Gly12Arg in subjects without glaucoma; and Asp208Glu and Thr353Ile in subjects with and without POAG. The previously reported 1-83(G-->A) and Arg76Lys polymorphisms were detected in both patients and controls and always occurred together. CONCLUSIONS: A different pattern of TIGR sequence variants exists in the Chinese than in non-Chinese populations. No common TIGR mutation that causes POAG was found. The occurrence of subjects without glaucoma who are heterozygous or homozygous for Arg46Stop suggests that reduction in the amount of TIGR protein does not cause glaucoma. Thus, the TIGR missense mutations known to cause POAG probably do not cause glaucoma by inactivating a normal TIGR function, but rather through the gain of a pathologic function.

Adolescent↗
PubMed2000

The association between cigarette smoking and ocular diseases.

OBJECTIVE: To review the effect of smoking on common ocular disorders. DATA SOURCES: Medline literature search, 1966 to 1999. STUDY SELECTION: The following key words were used: smoking; Graves' disease, age-related macular degeneration; glaucoma; cataract. DATA EXTRACTION: Epidemiological and experimental studies were reviewed. DATA SYNTHESIS: Cigarette smoking is an important risk factor for cardiovascular, respiratory, and malignant diseases. There is also a strong association between smoking and a number of common eye diseases, which include Graves' ophthalmopathy, age-related macular degeneration, glaucoma, and cataract. Despite the multifactorial aetiology of these ocular syndromes, smoking is an independent risk factor that has dose-response effects. It causes morphological and functional changes to the lens and retina due to its atherosclerotic and thrombotic effects on the ocular capillaries. Smoking also enhances the generation of free radicals and decreases the levels of antioxidants in the blood circulation, aqueous humour, and ocular tissue. Thus, the eyes are more at risk of having free-radical and oxidation attacks in smokers. CONCLUSION: Smoking, if continued, may perpetuate further ocular damage and lead to permanent blindness. Cessation of smoking and avoidance of passive smoking is advised to minimise the harmful effects of smoking on the eyes.

Cataract↗
PubMed1999

Isolated pedunculated congenital corneal dermoid.

PURPOSE: To investigate a case of isolated pedunculated congenital corneal dermoid. METHODS: Case report. RESULTS: In a 14-day-old infant, the pedunculated portion of the dermoid was removed and confirmed by histopathologic examination. No surgical complication or recurrence was encountered, and the patient is waiting for a rotational autokeratoplasty. CONCLUSIONS: Prompt treatment of such an unusual tumor is important to allow for visual rehabilitation and development.

Corneal Diseases↗
PubMed1999

Retinal complications after cataract extraction in patients with high myopia.

OBJECTIVE: To assess risk factors and incidence of retinal complications after cataract extraction in patients with high myopia. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: One hundred eighteen patients with highly myopic eyes who had an axial length of 26 mm or more (mean axial length, 30.13 +/- 2.08 mm) and who underwent cataract surgery over a period of 6 years were studied. INTERVENTION: Patients underwent cataract extraction either by extracapsular cataract extraction (ECCE) or phacoemulsification. Prophylactic argon laser photocoagulation was performed in 13 eyes for retinal tears recognized before surgery and in 13 eyes after surgery; neodymium:YAG (Nd:YAG) laser capsulotomy was performed for patients with posterior capsule opacification (PCO) that affected the vision. MAIN OUTCOME MEASURES: Incidence of retinal detachment and PCO and percentage of prophylactic argon laser or of Nd:YAG laser treatments. RESULTS: Of the 118 eyes, 73 (61.9%) underwent ECCE and 45 (38.1%) underwent phacoemulsification. Posterior capsule opacification was the most common complication and was found in 30 eyes (25.4%). Thirteen patients (11%) received prophylactic laser treatment for retinal tears before cataract operation, and 13 more patients (11%) had postoperative retinal tears requiring laser treatments. None of these patients developed retinal detachment. Two patients (1.69%) developed retinal detachment within 6 months after their operations. There were no intraoperative complications, and postoperative Nd:YAG capsulotomy was not performed in these two patients. CONCLUSIONS: Active searching and prophylactic laser treatments for retinal tears developed before and after cataract extraction in patients with high myopia are recommended. This may lower the incidence of postoperative retinal detachment.

Adult↗
PubMed1999

Culture-negative ulcerative keratitis after laser in situ keratomileusis.

A 40-year old man, highly myopic in both eyes, had laser in situ keratomileusis (LASIK) in the left eye in November 1996. Corneal melting and ulceration and fine striae-like interface infiltrates were noticed 1 day postoperatively. There was no response to intensive topical antibiotics in the form of hourly ofloxacin 3% (Tarivid), and satellite lesions developed on day 4. Corneal scrapings for gram stain and culture were done twice. No bacterial or fungal organisms were identified. Intensive topical fortified vancomycin (50 mg/mL) was added, and the lesions resolved gradually over the ensuing 2 weeks. Eighteen months after LASIK, refraction was -1.50 - 0.75 x 105 in the left eye, and uncorrected visual acuity was 20/70, correctable to 20/25 with spectacles.

Adult↗
PubMed1999

Management of severe flap wrinkling or dislodgment after laser in situ keratomileusis.

PURPOSE: To review the management and results of cases with severe flap wrinkling or dislodgment after laser in situ keratomileusis (LASIK). SETTING: University Eye Center, Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong. METHODS: Four patients with severe flap wrinkling or dislodgment after LASIK are described. Surgical repositioning of the flap was performed in all cases. Flap status, refractive changes, and final uncorrected and best corrected visual acuities were used to evaluate the outcome of flap repositioning. RESULTS: Flap repositioning required suturing in 2 patients, 1 of whom developed severe epithelial ingrowth with melting of the corneal flap and stromal bed and eventually required flap removal. The stromal inflammation resolved, and the corneal surface re-epithelialized after flap excision. In 2 other patients, wedge-shaped tissue excision (1.0 x 1.5 mm) from the superior portion of the corneal flap was necessary to allow better flap realignment. In 1 of these patients, the corneal flap was eventually converted to a free cap to correct residual wrinkling. At a mean follow-up of 15 months, the postoperative uncorrected visual acuity ranged from 20/20 to 20/60, and the best spectacle-corrected visual acuity (BSCVA) was 20/30 or better in all patients. In 1 patient, BSCVA decreased by 1 line. CONCLUSIONS: Flap dislodgment and wrinkling are serious postoperative complications of LASIK. Early recognition of these complications and prompt surgical management are crucial to achieve a successful surgical and visual outcome.

Adult↗
PubMed1999

Combined surgery for severe eye trauma with extensive iridodialysis, posterior lens dislocation, and intractable glaucoma.

A 44-year-old woman sustained a severe left eye contusion from the explosion of a plastic bottle containing fermented orange juice. This resulted in extensive iridodialysis, posterior crystalline lens dislocation, and intractable glaucoma. Eleven days after the injury, combined surgery of trabeculectomy with mitomycin-C, pars plana vitrectomy, lens removal, iridodialysis repair, and scleral-fixated intraocular lens implantation under general anesthesia was performed. Intraocular pressure (IOP) was under control until 5 weeks postoperatively; glaucoma implant surgery was then performed. At the last follow-up 15 months after the combined surgery, best corrected visual acuity was 20/50 and IOP was 15 mm Hg without medication. Combined surgery can be considered a safe, effective option in the management of severe eye trauma in selected cases.

Adult↗
PubMed1999

Sub-Tenon's anesthesia in vitreoretinal surgery: a needleless technique.

PURPOSE: To evaluate the safety and efficacy of "needleless" regional anesthesia via the sub-Tenon's route without adjunct facial nerve or subconjunctival block for vitreoretinal surgery. METHODS: Forty-eight consecutive patients were included and studied prospectively. The number, time, and volume of anesthetic solutions given were recorded. Any complications such as severe intraocular pressure rise or orbital hemorrhage were noted. Within 24 hours after surgery, the patients were asked to grade their level of pain during the procedure using a standard 10-point visual analog scale. The use of postoperative analgesic agents was recorded from the nurses' notes. Patient demography, number of previous vitreoretinal operations, preoperative diagnosis, and operative procedures performed were recorded. RESULTS: Thirty-seven (77%) patients needed only one or two infiltrations of anesthetic solution (range 1-5, mean 2.1). Ninety-two percent of patients reported a pain score of 0-2 on the visual analog scale (range 0-5, mean 1.17). Ninety percent of patients required no analgesic or just acetaminophen for the control of postoperative pain. The other patients received a single dose or multiple doses of codeine. All patients had adequate akinesia and anesthesia. No complications were encountered. CONCLUSION: Needleless regional anesthesia appears to be safe and effective and can thus be considered as an alternative method of anesthesia in suitable vitreoretinal cases.

Adolescent↗
PubMed1998

Behavioral recovery in 6-hydroxydopamine-lesioned rats by cotransduction of striatum with tyrosine hydroxylase and aromatic L-amino acid decarboxylase genes using two separate adeno-associated virus vectors.

Parkinson's disease (PD) is characterized by the progressive loss of the dopaminergic neurons in the substantia nigra and a severe decrease in dopamine in the striatum. A promising approach to the gene therapy of PD is intrastriatal expression of enzymes in the biosynthetic pathway for dopamine. Tyrosine hydroxylase (TH) catalyzes the synthesis of L-dopa, which must be converted to dopamine by aromatic L-amino acid decarboxylase (AADC). Since the endogenous AADC activity in the striatum is considered to be low, coexpression of both TH and AADC in the same striatal cells would increase the dopamine production and thereby augment the therapeutic effects. In the present study, the TH gene and also the AADC gene were simultaneously transduced into rat striatal cells, using two separate adeno-associated virus (AAV) vectors, AAV-TH and AAV-AADC. Immunostaining showed that TH and AADC were coexpressed efficiently in the same striatal cells in vitro and in vivo. Moreover, cotransduction with these two AAV vectors resulted in more effective dopamine production and more remarkable behavioral recovery in 6-hydroxydopamine (6-OHDA)-lesioned rats, compared with rats receiving AAV-TH alone (p < 0.01). These findings suggest an alternative strategy for gene therapy of PD and indicate that the simultaneous transduction with two AAV vectors can extend their utility for potential gene therapy applications.

Animals↗
PubMed1998

An uncommon malignant neoplasm of the caruncle: report of a case of undifferentiated carcinoma.

The caruncle is an uncommon site for the occurrence of neoplasm despite its diverse histological composition of conjunctival, lacrimal, and skin tissues. The following case report describes a 66-year-old man who suffered from a primary undifferentiated carcinoma of the left caruncle. He remained well with no evidence of recurrence 24 months after a complete surgical excision. To our knowledge, this could represent the first case of undifferentiated carcinoma of the caruncle to be reported in the English literature. Early detection and complete excision for this type of lesion could lead to a satisfactory clinical outcome.

Aged↗
PubMed1998

Intraoperative mitomycin C to prevent recurrence of pterygium after excision: a 30-month follow-up study.

OBJECTIVE: The purpose of the study was to examine the efficacy of intraoperative mitomycin C (MMC) in preventing recurrence of pterygium after excision and the postoperative complications encountered. DESIGN: The study design was a prospective, randomized, clinical trial. PARTICIPANTS: A total of 180 primary and recurrent pterygia were recruited for the study. They were randomized into five groups: A, control with no MMC; B, 0.02% MMC for 5 minutes; C, 0.04% MMC for 5 minutes; D, 0.02% MMC for 3 minutes; and E, 0.04% MMC for 3 minutes. INTERVENTION: All patients received pterygium excision with or without the above four modes of intraoperative MMC application. MAIN OUTCOME MEASURES: Recurrence of pterygium and postoperative complications such as superficial scleral melting were measured. RESULTS: At a mean follow-up of 30 (groups A-C) and 20 months (groups D and E), the respective recurrence rates in groups A through E were 75%, 8.3%, 8.6%, 42.9%, and 22.9%. There were two cases of postoperative superficial scleral melting in group C. Otherwise, no major postoperative complications were encountered. CONCLUSIONS: The midterm results of a single intraoperative application of MMC at the concentration of 0.02% for 5 minutes are encouraging. Its application as an adjunctive therapy for the surgical treatment of pterygium appeared to be safe and effective. However, because of the possibility of serious late complications, the authors suggest that this procedure be reserved for patients who have high probability of recurrence after excision of pterygium.

Adult↗