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Biomedical subjects

D S Lam

Publications and source records attributed to D S Lam.

At least 19 recordsLinked to original sources
PubMed2000

Absence of trabecular meshwork-inducible stretch response (TISR)/oculomedin gene and proximal promoter mutation in primary open angle glaucoma patients.

We investigated the coding exon and promoter sequence in the trabecular meshwork-inducible stretch response (TISR)/oculomedin gene for mutations in Chinese primary open angle glaucoma (POAG) subjects. The entire TISR/oculomedin coding sequence, together with 138 bp of promoter sequence 5' to the start codon and 170 bp of the 3' untranslated region in 110 Chinese POAG patients and 108 unrelated control subjects without glaucoma, aged 50 years or above, were screened for alterations by DNA sequencing. One heterozygous sequence alteration, K28E, was identified in one control subject, and two homozygous sequence alterations, K28K and 135+36delC, were universally found in every sample. As a result, no common TISR/ oculomedin coding sequence nor any proximal promoter mutation that causes POAG was found. The effect of TISR/ oculomedin in glaucoma has yet to be established.

Adolescent↗
PubMed2000

Ocular hypertensive response to topical dexamethasone in children: a dose-dependent phenomenon.

OBJECTIVE: To investigate the ocular-hypertensive response to different dosages of topical dexamethasone eye drops in Chinese children. DESIGN: Prospective, randomized clinical trial. PARTICIPANTS: Thirty-one consecutive children undergoing bilateral strabismus surgery. INTERVENTION: Topical dexamethasone (0.1%) was administered to children undergoing bilateral strabismus surgery. They were all less than 10 years of age. One eye was randomized to receive a regimen of four times daily, and another received a twice daily regimen. Intraocular pressure (IOP) was serially measured in the postoperative period for 4 weeks or more. Topical steroids were discontinued if IOP was 30 mmHg or more. MAIN OUTCOME MEASURES: Intraocular pressure was measured on the day before the surgery, on postoperative days 1, 3, 5, 8, 12, 15, 22, 29, and 2 weeks thereafter until the IOP reached preoperative levels. Peak IOP, IOP net increase, and time to reach an IOP more than 20 mmHg in the two study groups were analyzed. RESULTS: A total of 31 patients (20 male, 11 female) were examined. The mean age was 5.8 +/- 2.0 years (range, 2-10 years). Preoperative IOP in groups treated twice daily and four times daily were similar. After topical dexamethasone treatment, both groups showed a significant rise in peak IOP compared with preoperative values (twice daily, 25.2 +/- 6.8 mmHg vs. 14.3 +/- 2.4 mmHg, P < 0.001; four times daily, 28.7 +/- 6.9 mmHg vs. 14.3 +/- 2.9 mmHg, P < 0.001). The peak IOP was significantly higher in the four times daily group (P < 0.001), as was the net increase in IOP (twice daily, 10.9 +/- 5.8 mmHg vs. four times daily, 14.5 +/- 6.4 mmHg; P < 0.001). There was no difference in time for both groups to achieve the peak IOP, but the time to exceed its upper normal value (20 mmHg) was shorter in the four times daily group (twice daily, 12.3 +/- 9.1 days vs. four times daily, 10.0 +/- 7.4 days; P < 0.05). CONCLUSIONS: In children treated with topical dexamethasone, ocular hypertension occurs in a dose-dependent manner. Children in the four times daily group had a quicker onset and more severe ocular hypertensive response than the twice daily group. Nevertheless, even the twice daily regimen produced significant IOP rise, suggesting that dexamethasone use in children should be avoided if possible, and it would be desirable to monitor the IOP twice weekly when it is administered to children.

Administration, Topical↗
PubMed2000

Effect of laser in situ keratomileusis on tear stability.

OBJECTIVE: Patients frequently experience dry eye symptoms after laser in situ keratomileusis (LASIK). The mechanisms that lead to these changes are not well understood. The purpose of this study was to investigate the effect of LASIK on tear function. DESIGN: Prospective, comparative, nonrandomized interventional trial. PARTICIPANTS: Fifty-eight consecutive patients (96 eyes) who underwent myopic LASIK treatment. METHODS: The prospective study involved 58 consecutive patients (96 eyes) who underwent sequential or bilateral LASIK for the correction of myopia. Dry eye symptoms, standardized Schirmer test values, basal tear secretion test, and tear break-up time were measured before surgery and 1 day, 1 week, and 1 month after surgery. MAIN OUTCOME MEASURES: Schirmer test value, basal tear secretion value, and tear break-up time. RESULTS: Before surgery, 15.6% of patients (15/96) had dry eye symptoms. After surgery, 94.8% of patients (91/96), 85.4% of patients (82/96), and 59.4% of patients (57/96) experienced dry eye symptoms at 1 day, 1 week, and 1 month, respectively. Schirmer test value (13.32 +/- 10. 67 mm) increased at 1 day (14.48 +/- 10.57 mm; P = 0.25) and subsequently decreased at 1 week (11.18 +/- 9.81 mm; P = 0.05) and at 1 month (10.83 +/- 10.02 mm; P = 0.03). Basal tear secretion test value (8.49 +/- 8.48 mm) decreased at 1 day (6.80 +/- 6.48 mm; P = 0.05), at 1 week (5.97 +/- 6.88 mm; P = 0.005), and at 1 month (5.89 +/- 6.24 mm; P = 0.007). Tear break-up time (5.32 +/- 2.35 seconds) decreased 1 day (4.14 +/- 1.90 seconds; P < 0.001) and 1 week (4.49 +/- 1.70 seconds; P = 0.004) after surgery and recovered by 1 month after surgery (5.09 +/- 3.03 seconds; P = 0.52). Poor preoperative tear functions with a Schirmer test value less than 10 mm was a significant risk factor (72% vs. 46%; relative risk, 1.58 [1.10-2.26]) for experiencing dry eye symptoms at 1 month after surgery. CONCLUSIONS: Dry eye symptoms are common after myopic LASIK surgery. Laser in situ keratomileusis significantly altered the tear break-up time, Schirmer test values, and basal tear secretion. Patients with preexisting tear flow abnormality as demonstrated by Schirmer test values less than 10 mm are especially at risk of experiencing dry eye symptoms.

Adult↗
PubMed2000

Fornix-based trabeculectomy with Wise's suture technique in Chinese patients.

OBJECTIVE: To assess the safety and efficacy of fornix-based trabeculectomy with Wise's suture technique in Chinese subjects. DESIGN: A retrospective noncomparative case series. PARTICIPANTS: Forty-eight eyes of 44 Chinese subjects that underwent fornix-based trabeculectomy combined with intraoperative 0.4 mg/ml mitomycin-C for 3 to 5 minutes were studied. INTERVENTION: Conjunctival wound closure of all eyes was with the Wise's technique using 9-0 nylon suture to prevent leakage at the corneolimbal interface. MAIN OUTCOME MEASURES: The success rate, with or without antiglaucoma medication, the complication rate, and the longevity of the drainage blebs were analyzed. RESULTS: At a mean follow-up period of 21.8 +/- 4.5 months, 75% (36 eyes) had postoperative intraocular pressure of 21 mmHg or less. Of these, 23 eyes (47.9%) required no antiglaucoma medication, 7 eyes (14.6%) required one medication, 3 eyes (6.3%) required two medications, and 3 eyes (6.3%) required three medications. Ten eyes (21%) had early wound leak. Two eyes (4.2%) required surgical repair. Two eyes (4%) had hypotonous maculopathy. No other major complications were encountered. CONCLUSIONS: Fornix-based trabeculectomy with adjunctive mitomycin-C using Wise's suture technique appears to be both safe and effective in Chinese subjects.

Antimetabolites, Antineoplastic↗
PubMed2000

Corneal laceration with total but isolated aniridia caused by a pecking injury.

A 38-year-old man sustained a left eye injury after being attacked by a mynah bird. Ocular examination revealed a beak-shaped, full-thickness corneal laceration with total aniridia in the left eye. No other ocular injury was observed, and the lens and posterior segment remained normal over the subsequent 3 months. A penetrating keratoplasty was planned for visual restoration.

Adult↗