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Wai-Ching Lam

Publications and source records attributed to Wai-Ching Lam.

8 recordsLinked to original sources
PubMed2006

Observations on the management of Coats' disease: less is more.

BACKGROUND: In this article we share our experience of treating various severities of Coats' disease and focus on optimal therapy for advanced disease. METHODS: Retrospective chart review of 10 patients treated with varied techniques including intraocular surgery, cryopexy and/or laser photocoagulation. RESULTS: Nine patients were male. At presentation the average age was 4.6 years (range 21 months-7 years), the average number of retinal quadrants involved with telangiectasia was 2.7 (range 1-4, median 3), eight of the 10 patients had retinal detachment, six of these being total, and all patients had macular involvement with either exudate or fibrosis. Average follow-up was 2.3 years (range 1-4.5 years). The best visual outcomes were observed in patients who presented with less severe disease. For example, the only four patients to maintain ambulatory vision all presented without total retinal detachment, two or fewer quadrants of retinal telangiectasia and a visual acuity better than light perception. No patient developed secondary angle closure glaucoma, and all patients have kept a cosmetically acceptable eye. CONCLUSION: In this limited series, visual outcomes in the setting of advanced Coats' disease are largely dependent on disease severity and visual status at the time of presentation. Minimally invasive surgery with vitreous infusion through the pars plana, combined with external drainage of subretinal fluid together with cryotherapy and/or laser photocoagulation is sufficient to effect retinal re-attachment and prevent loss of the eye.

Child↗
PubMed2006

Agreement of the Heidelberg Retina Tomograph II macula edema module with fundus biomicroscopy in diabetic maculopathy.

OBJECTIVES: To estimate the agreement between the macular edema maps (MEMs) of the Retina Module of the Heidelberg Retina Tomograph II (Heidelberg Engineering, Heidelberg, Germany) and contact lens fundus biomicroscopy (FB) and to assess the influence of combining MEM data with the results of short-wavelength automated perimetry (SWAP) and fluorescein angiography (FA) on diagnostic test performance. DESIGN: Prospective, observational case series. METHODS: Twenty patients (20 eyes) with diabetic retinopathy with or without clinically manifest macular edema (11 and 9 eyes, respectively) were enrolled. All patients underwent full ophthalmologic examination and also MEM assessment, SWAP, and FA. RESULTS: Using FB as the "gold standard," the agreement between the MEMs and FB was very good (Kendall coefficient of concordance, 0.80). Macular edema maps showed good agreement with FA and SWAP (Kendall coefficient, 0.64 and 0.65). Virtually all of the edematous areas detected with MEM but not seen clinically had decreased sensitivity on SWAP and/or fluorescein leakage. CONCLUSIONS: Macular edema maps demonstrated very good agreement with FB. Combining the results of FA and SWAP with those of the MEMs provided supporting evidence of concomitant blood-retinal barrier leakage and visual dysfunction, respectively, in areas of early retinal thickening. Prospective studies are ongoing to fully assess the diagnostic test performance of MEMs in the detection of early and progressive diabetic macular edema.

Adult↗
PubMed2006

Medical students' self-confidence in performing direct ophthalmoscopy in clinical training.

BACKGROUND: Although direct ophthalmoscopy is an important skill that medical students must practice to gain proficiency, limited time is generally available in medical school curricula. More targeted and effective teaching could result from a clearer understanding of medical students' self-reported needs and weaknesses in performing direct ophthalmoscopy. METHODS: A cross-sectional survey was conducted at a Canadian university to determine the confidence of medical students in their skill in performing direct ophthalmoscopy. The responses of 208 participants who volunteered to complete a 21-item questionnaire were analyzed. RESULTS: Although clerks were significantly more confident in their overall skill (chi2=28.03, p<0.001) than were first- and second-year students, 47% of clerks were "not at all" or only "a little" confident in performing direct ophthalmoscopy on an undilated pupil. Respondents who had practiced on more than 10 occasions outside of formal teaching were significantly more confident in their overall skill than those who had not (chi2=22.94, p<0.001). Overall, 87% (77% of clerks) were "quite" or "extremely" interested in more practice and training on direct ophthalmoscopy. INTERPRETATION: A large proportion of medical students reported not being confident in various aspects of their skill in performing direct ophthalmoscopy. Self-confidence was significantly greater among students who practiced outside of formal teaching sessions. Most students were interested in additional training, and medical schools should emphasize the importance of practicing whenever appropriate.

Clinical Clerkship↗
PubMed2005

Endoscopic closure of a cyclodialysis cleft.

Numerous surgical procedures have been proposed to close cyclodialysis clefts. We describe a novel technique, direct cyclopexy under microendoscopic view, in a patient with persistent hypotony despite previous attempts at both surgical repair and cryotherapy for her cyclodialysis cleft.

Child, Preschool↗
PubMed2005

Color visual evoked potentials in children with type 1 diabetes: relationship to metabolic control.

PURPOSE: To examine the association between metabolic control (HbA(1c)) and the chromatic mechanisms of children with type 1 diabetes (T1D), by using the color visual evoked potential (VEP). METHODS: Fifty children with T1D (age range, 6-12.9 years) and 33 age-matched control subjects were tested. VEPs were recorded by placing five electrodes on the scalp according to the International 10/20 System of Electrode Placement. Active electrodes O1, O2, and Oz were placed over the visual cortex. Short-wavelength (S), and long- and medium-wavelength (LM) color stimuli consisted of vertical, photometric isoluminant (1 cyc/deg) gratings presented in a pattern onset (100 ms)-offset (400 ms) mode. Achromatic vertical gratings were presented at 3 cyc/deg. Primary outcome measure was VEP latency. The relationship between S, LM, and achromatic VEP latency, and HbA(1c) was determined by ANCOVA regression. RESULTS: S-, LM-, achromatic VEP latencies were not associated significantly with HbA(1c). Pubertal status, however, was associated significantly (P = 0.0114) and selectively with S-VEP latency. Pubertal children with T1D had delayed (mean delay, 9.5 ms) S-VEP latencies when compared with the prepubertal children with T1D. However, there was no statistically significant difference (P = 0.1573) in the effect of pubertal status on S-VEP latency between the T1D and control groups. CONCLUSIONS: Pubertal status rather than HbA(1c) appears to affect selectively the S-VEP latency of preteen children with T1D. Further study is warranted to determine whether the delay in S-VEP latency in pubertal children with T1D changes over time and whether this change could be a predictive marker for future development of background diabetic retinopathy.

Blood Glucose↗
PubMed2004

Retinal toxicity of intravitreal ganciclovir in rabbit eyes following vitrectomy and insertion of silicone oil.

BACKGROUND: Although intravitreal ganciclovir dosages up to 500 microg have been demonstrated to be safe in some studies, other studies have shown toxic retinal effects in rabbit eyes without silicone oil at lower dosages. In current clinical practice, the same dosage of intravitreal antiviral agent is given regardless of whether there has been retinal detachment repair with silicone oil. We performed a study to investigate, in rabbit eyes following vitrectomy and silicone oil insertion, the retinal toxicity of serial intravitreal injections of ganciclovir, using dosages previously found not to produce significant toxic effects in nonvitrectomized eyes. METHODS: Twenty-eight eyes of 14 New Zealand pigmented rabbits underwent pars plana vitrectomy and silicone oil insertion. One eye of each animal received an intravitreal ganciclovir injection twice weekly for 2 weeks. The other eye received 0.1 mL of normal saline as a control. Three dosages of ganciclovir (50, 100 or 200 microg/0.1 mL) were used in three groups of three to six animals. Scotopic electroretinography and histologic examination were performed 2 weeks postoperatively. RESULTS: No differences in scotopic b-wave threshold (p = 0.23, 0.78 and 0.50 for ganciclovir dosages of 50, 100 and 200 microg/0.1 mL respectively, Mann-Whitney U test) or in light microscopy findings were noted between the treatment and control eyes at any dosage of ganciclovir. Surgical complications were observed in eight eyes; the data for these eyes were not used for analysis. INTERPRETATION: Ganciclovir dosages of up to 200 microg/0.1 mL appear to be safe for serial intravitreal injection in rabbit eyes following vitrectomy and silicone oil insertion.

Animals↗
PubMed2003

Retinopathy in sickle cell trait: does it exist?

BACKGROUND: Patients with sickle cell trait and concomitant systemic disease are known to be at risk for proliferative retinopathy. However, there are reports of retinopathy in patients with sickle cell trait without systemic disease. There are no population-based studies addressing the risk of sickle cell retinopathy in this group. We performed a study to clarify the relation between sickle cell trait and retinopathy in healthy subjects. METHODS: We reviewed the medical records of 100 children with sickle cell disease who attended the Sickle Cell Clinic at the Hospital for Sick Children, Toronto. We then contacted 200 parents with sickle cell trait, of whom 32 agreed to participate in the study. All participants were proven to have hemoglobin AS status with prior hemoglobin electrophoresis. An ophthalmologic history was obtained, and a complete ophthalmologic examination was performed. We defined sickle cell retinopathy as any salmon patch hemorrhages, iridescent spots, black sunbursts, retinal neovascularization or retinal detachment. The evaluation also included attempts to identify the more subtle signs of sickle cell retinopathy, such as optic nerve head vascular changes, vascular tortuosity, macular changes (e.g., microaneurysms and vascular loops) and peripheral arteriovenous anastamoses. Blood samples were obtained for complete blood count, reticulocyte count and smear. RESULTS: We found no cases of sickle cell retinopathy among the 32 subjects. Ten of 30 subjects had a high reticulocyte count (greater than 120 x 10(9)/L); however, there were no associated eye findings in this subgroup. INTERPRETATION: Our results indicate that there is no increased risk of retinopathy in healthy people with sickle cell trait.

Adult↗