Publications by authors named "Robert F Lam"

16 Publications

  • Page 1 of 1

Comparison of two-year treatment outcomes between subthreshold micropulse (577 nm) laser and aflibercept for diabetic macular edema.

Jpn J Ophthalmol 2021 Jun 14. Epub 2021 Jun 14.

Department of Ophthalmology, Caritas Medical Centre, 111 Wing Hong Street, Sham Shui Po, Hong Kong.

Purpose: To compare two-year treatment outcomes of subthreshold micropulse (577 nm) laser and aflibercept for diabetic macular edema (DME).

Study Design: Retrospective case-control study.

Methods: A total 164 eyes in 164 DME patients treated with either micropulse laser (86 eyes) or intravitreal aflibercept monotherapy (78 eyes) were recruited. Main outcome measures included at least five Early Treatment Diabetic Retinopathy Study (ETDRS) letters' improvement from baseline at 6, 12 and 24 months.

Results: Rescue aflibercept was initiated in 24% of eyes in micropulse laser group. At 6-month visit the aflibercept group achieved a higher percentage of eyes with at least 5-letter visual acuity improvement than micropulse laser group (56% vs 38%, P = 0.044), however, this was not the case at 12-month (45% vs 49%, P = 0.584) and 24-month visits (49% vs 57%, P = 0.227). At 6-month visit the aflibercept group achieved a higher percentage of eyes with at least 10% improvement of central macular thickness (73% vs 49%, P = 0.005), but this was not the case at 12-month (73% vs 70%, P = 0.995) and 24-month visits (85% vs 84%, P = 0.872).

Conclusion: Aflibercept achieved faster and higher rates of anatomical and functional improvement than micropulse laser in DME patients. Long term efficacy of treatment did not result in significant differences between aflibercept monotherapy and micropulse laser in DME patients. Primary treatment of micropulse laser with deferred rescue aflibercept might be the treatment option without reducing the chance of visual improvement in DME eyes.
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http://dx.doi.org/10.1007/s10384-021-00846-4DOI Listing
June 2021

Retrospective analysis of the risk factors for developing phacomorphic glaucoma.

Indian J Ophthalmol 2011 Nov-Dec;59(6):471-4

The Eye Institute, The University of Hong Kong, Hong Kong, People's Republic of China.

Aim: To determine the risk factors for developing phacomorphic glaucoma in eyes with mature cataracts.

Materials And Methods: This is a case-control study comprising of 90 eyes with phacomorphic glaucoma and 90 age- and sex-matched control eyes with mature cataracts without phacomorphic glaucoma. Patients with pre-existing glaucoma, previous intraocular surgery and /or absence of documented axial lengths were excluded from this study. Binary logistic regression analysis of the variables, axial length and anterior chamber depth, was performed. Anterior chamber depth of the contralateral eye was used as a proxy measure of the pre-phacomorphic state in the eye with phacomorphic glaucoma as majority of them first presented to our center during the phacomorphic attack without prior measurements of the pre-phacomorphic ACD or lens thickness; therefore, their anterior chamber depth would not be representative of their pre-phacomorphic state. Axial length of 23.7 mm was selected as a cut-off for dichotomized logistic regression based on the local population mean from published demographic data.

Results: The mean age was 73.1 ± 10.2 years. All phacomorphic and control eyes were ethnic Chinese. The mean presenting intraocular pressures were 49.5 ± 11.8 mmHg and 16.7 ± 1.7 mmHg in the phacomorphic and control eyes respectively (P< 0.0001), whilst the median Snellen best corrected visual acuity were light perception and hand movement in the phacomorphic and control eyes respectively. Eyes with phacomorphic glaucoma had shorter axial length of 23.1 ± 0.9 mm median when compared with that of control eyes, 23.7 ± 1.5 mm (P = 0.0006). Eyes with AL ≤ 23.7 mm were 4.3 times as likely to develop phacomorphic glaucoma when compared with AL > 23.7 mm (P = 0.003).

Conclusion: Axial length less than ≤ 23.7 mm was a risk factor for developing phacomorphic glaucoma. Eyes with AL shorter than the population mean were 4.3 times as likely to develop phacomorphic glaucoma compared with eyes with longer than average AL. In an area where phacomorphic glaucoma is prevalent and medical resources are limited, patients with AL shorter than their population mean may be considered for earlier elective cataract extraction as a preventive measure.
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http://dx.doi.org/10.4103/0301-4738.86316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3214418PMC
February 2012

The effect of parental history of myopia on children's eye size and growth: results of a longitudinal study.

Invest Ophthalmol Vis Sci 2008 Mar;49(3):873-6

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong.

Purpose: To evaluate the effect of parental myopia on eye size and growth in Chinese children.

Methods: A school-based, cross-sectional survey was performed in Chinese children 5 to 16 years of age. A longitudinal cohort study was conducted 1 year later. The effects of parental myopia, parental education level, and near work performed by the child on the refractive error and ocular biometry of the child were assessed.

Results: There were 7560 children enrolled in the initial study (response rate: 76.3%). One year later, 4468 children (response rate: 75.9%) in the original cohort (with the exception of those who had completed primary schooling) were evaluated, to determine eye growth. Although children with a stronger parental history of myopia tended to be less hyperopic before the onset of myopia (spherical equivalent refraction [SER] = 0.43 D, 0.67 D, and 0.68 D in children with two, one, and no myopic parents respectively; P = 0.007), the axial lengths did not follow the same pattern (axial length [AL] = 23.11, 23.07, and 23.15 mm; P = 0.429). Eye growth and myopic shift in refraction occurred more rapidly among children with a stronger parental history of myopia (annual AL growth/myopia progression = 0.37 mm/-0.22 D, 0.26 mm/-0.07 D, and 0.20 mm/-0.02 D in children with two, one, and no myopic parents, respectively; P < 0.001).

Conclusions: Ocular biometric data in Chinese children suggest that parental history of myopia influences the growth rate of the eye, rather than its size before the onset of myopia, as previously reported in Caucasian children. Further longitudinal studies involving children of different ethnicities are warranted.
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http://dx.doi.org/10.1167/iovs.06-1097DOI Listing
March 2008

Retinal redetachment after silicone oil removal in proliferative vitreoretinopathy: a prognostic factor analysis.

Am J Ophthalmol 2008 Mar 11;145(3):527-533. Epub 2008 Jan 11.

Hong Kong Eye Hospital, and the Eye Institute, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.

Purpose: To determine the prognostic factors associated with retinal redetachment after 1300-centistokes silicone oil removal in rhegmatogenous retinal detachments (RDs) associated with grade C proliferative vitreoretinopathy (PVR).

Design: Nonrandomized, retrospective, comparative interventional trial.

Methods: One hundred and forty-seven eyes with RD and grade C PVR treated with silicone oil tamponade, with subsequent silicone oil removal, in an institutional setting. Main outcome measures included anatomic success, defined as complete retinal attachment after silicone oil removal, and best-corrected visual acuity (BCVA) after silicone oil removal.

Results: Silicone oil was removed after a mean tamponade period of 12.4+/-9.8 months. The mean follow-up after silicone oil removal was 22.1+/-18.7 months (range, 6.0 to 71.0 months). The retina remained attached in 120 eyes after oil removal. The overall anatomic success rate was 81.6%+/-3.2%. Logistic regression showed that an increased number of previous unsuccessful RD surgeries (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.19 to 0.80; P=.010) and longer axial lengths (OR, 0.42; 95% CI, 0.15 to 0.87; P=.032) were associated with a lower anatomic success rate. Previous vitrectomy, previous scleral buckling procedure, 12% perfluoropropane-air exchange immediately after silicone oil removal, and duration of silicone oil tamponade were not statistically associated with the anatomic success rate. Anatomic success was associated with a significantly better BCVA (1.169+/-0.475 vs 1.520+/-0.381 logarithm of the minimum angle of resolution; P<.001).

Conclusions: The number of previous surgeries and axial length, rather than the nature of the previous surgical procedures, were significant prognostic factors for anatomic success after silicone oil removal.
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http://dx.doi.org/10.1016/j.ajo.2007.10.015DOI Listing
March 2008

Quality of reporting of key methodological items of randomized controlled trials in clinical ophthalmic journals.

Ophthalmic Epidemiol 2007 Nov-Dec;14(6):390-8

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Hong Kong, People's Republic of China.

Purpose: To evaluate the reporting quality of key methodological items in randomized controlled trials (RCTs) in four general clinical ophthalmology journals.

Methods: The reporting of 11 key methodological items in RCTs published in American Journal of Ophthalmology, Archives of Ophthalmology, British Journal of Ophthalmology and Ophthalmology in the year 2005 was assessed.

Results: Sixty-seven eligible RCTs were assessed and the mean number of items reported was 6.3 per RCT. No significant difference in the mean number of items reported was found between the four journals (P=0.20). The most frequently reported item was ethics approval and informed consent (97.0%), followed by masking status (85.1%), description of withdrawals (76.1%), adverse events (73.1%), and intention-to-treat analysis (71.6%). Details on sequence generation, randomization restriction, allocation concealment, allocation implementation, patient flow diagrams, and sample size calculation were reported in <50% of the RCTs assessed. Both sample size and page length of the RCTs correlated with the number of methodological items reported (P=0.024 and P=0.008, respectively).

Conclusions: Similar to other specialties, rooms for improvement exist in the reporting of key methodological items of RCTs in clinical ophthalmic journals. Stricter adoption of the CONSORT statement might enhance the reporting quality of RCTs in ophthalmic journals.
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http://dx.doi.org/10.1080/09286580701344399DOI Listing
February 2008

Pars plana vitrectomy and perfluoropropane (C3F8) tamponade for retinal detachment due to myopic macular hole: a prognostic factor analysis.

Am J Ophthalmol 2006 Dec 1;142(6):938-44. Epub 2006 Sep 1.

Department of Ophthalmology and Visual Sciences, Chinese University of Hong Kong, and Vitreoretinal Service, Hong Kong Eye Hospital, Hospital Authority Ophthalmic Services, Kowloon, Hong Kong.

Purpose: To determine the prognostic factors associated with anatomical success in the treatment of retinal detachment (RD) due to myopic macular hole by pars plana vitrectomy (PPV) and perfluoropropane (C3F8) gas tamponade.

Design: Retrospective, interventional, comparative case series.

Methods: In an institutional setting, 57 eyes with myopic macular hole RDs treated by PPV and C3F8 tamponade, with or without concomitant internal limiting membrane (ILM) peeling, endolaser photocoagulation, and/or phacoemulsification, were analyzed. Outcome measures were anatomical success, defined as closure of macular hole with reattachment of the surrounding retina, and postoperative best-corrected visual acuity (BCVA).

Results: The mean postoperative follow-up was 26.9 +/- 16.5 months. The anatomical success rate after primary PPV and C3F8 tamponade was 63.2%. Regression analysis showed that shorter axial lengths (odds ratio [OR] = 6.73, 95% confidence interval [95% CI] 1.86 to 12.22, P = .010), concomitant ILM peeling (OR 1.59, 95% CI 1.14 to 2.38, P = .013), and shorter duration of macular hole RD (OR 0.81, 95% CI 0.67 to 0.98, P = .033) were associated with a higher anatomical success. The mean pre- and postoperative BCVAs were 1.430 +/- 0.273 (range, 0.523 to 1.700) and 1.403 +/- 0.271 (range, 0.699 to 1.800) logarithm of minimal angle of resolution units, respectively. The postoperative BCVA was significantly better in eyes with macular hole closure than in eyes without (P = .021).

Conclusions: Axial length, concomitant ILM peeling, and duration were important prognostic factors for PPV and C3F8 tamponade in the treatment of myopic macular hole RDs.
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http://dx.doi.org/10.1016/j.ajo.2006.07.056DOI Listing
December 2006

Comparison of outcomes of primary scleral-fixated versus primary anterior chamber intraocular lens implantation in complicated cataract surgeries.

Ophthalmology 2007 Jan 27;114(1):80-5. Epub 2006 Oct 27.

Department of Ophthalmology & Visual Sciences, Chinese University of Hong Kong, Hong Kong, China.

Objective: To compare the visual outcomes and complication profiles of primary scleral-fixated intraocular lens (SFIOL) versus primary anterior chamber intraocular lens (ACIOL) implantation in cataract surgeries complicated by inadequate capsular support.

Design: Retrospective, interventional, comparative cases series.

Participants: Thirty-six eyes of 36 patients undergoing SFIOL implantation (group 1) and 46 eyes of 46 patients undergoing ACIOL implantation (group 2).

Methods: Retrospective analysis of medical records of a consecutive series of complicated cataract surgeries with primary SFIOL or ACIOL implantation.

Main Outcome Measures: Postoperative best-corrected visual acuity (BCVA), intraoperative and postoperative complications, if any, and postoperative corneal endothelial cell counts. A multiple linear regression model was constructed with postoperative BCVA as the dependent variable and with IOL group (SFIOL vs. ACIOL), preoperative BCVA, surgeon's operative experience, planned operation, and patient's age as independent variables.

Results: Fifty-eight percent (group 1) and 37% (group 2) of patients underwent phacoemulsification, whereas the rest underwent extracapsular cataract extraction. The mean postoperative follow-up was 33.4+/-17.9 months (range, 6-61 months). Postoperative Snellen BCVA of 20/40 or better was achieved in 47.2% (group 1) and 71.7% (group 2) of patients (P = 0.038). Regression analysis showed that primary ACIOL implantation was associated with a significantly better postoperative BCVA of -0.157 on the logarithm of minimum angle of resolution scale (95% confidence interval, -0.306 to -0.007; P = 0.040), compared with primary SFIOL implantation. Although both the number of eyes with complications and the total number of complications were higher in the SFIOL group, the differences in early (P = 0.073) and late (P = 0.377) complications were not statistically significant.

Conclusions: The results indicate that satisfactory results are achieved with primary implantation of current open-loop ACIOLs during cataract surgery complicated by loss of posterior capsule integrity. Eyes with these IOLs fared better than a cohort of eyes undergoing SFIOL implantation in a similar situation, at intermediate-term follow-up. Further prospective clinical trials with longer follow-up may help to evaluate the long-term visual outcomes and complication profiles after primary implantation of these lenses.
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http://dx.doi.org/10.1016/j.ophtha.2005.11.024DOI Listing
January 2007

How evidence-based are publications in clinical ophthalmic journals?

Invest Ophthalmol Vis Sci 2006 May;47(5):1831-8

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Hong Kong, People's Republic of China.

Purpose: To evaluate the methodological quality and level of evidence of publications in four leading general clinical ophthalmology journals.

Methods: All 1919 articles published in the American Journal of Ophthalmology, Archives of Ophthalmology, British Journal of Ophthalmology, and Ophthalmology in 2004 were reviewed. The methodological rigor and the level of evidence in the articles were rated according to the McMaster Hedges Project criteria and the Oxford Centre for Evidence-Based Medicine levels of evidence.

Results: Overall, 196 (24.4%) of the 804 publications that were included for assessment met the Hedges criteria. Articles on economics evaluation and those on prognosis achieved the highest passing rate, with 80.0% and 74.4% of articles, respectively, meeting the Hedges criteria. Publications on etiology, diagnosis, and treatment fared less well, with respective passing rates of 28.3%, 20.2%, and 14.7%. Published systematic reviews and randomized controlled trials were uncommon in the ophthalmic literature, at least in these four journals during 2004. According to the Oxford criteria, 57.6% of the articles were classified as level 4 evidence compared with 18.1% classified as level 1. Articles on prognosis had the highest proportion (43.0%) rated as level 1 evidence. Generally, articles that reached the Hedges threshold were rated higher on the level-of-evidence scale (Spermans rho = 0.73; P < 0.001).

Conclusions: The methodological quality of publications in the clinical ophthalmic literature was comparable to that in the literature of other specialties. There was substantial heterogeneity in quality between different types of articles. Future methodological improvements should focus on the areas identified as having the largest deficiencies.
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http://dx.doi.org/10.1167/iovs.05-0915DOI Listing
May 2006

Extent and predictors of microbial hand contamination in a tertiary care ophthalmic outpatient practice.

Invest Ophthalmol Vis Sci 2005 Oct;46(10):3578-83

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong.

Purpose: To measure the extent of microbial hand contamination among ophthalmologists during routine clinic practice and examine its association with hand cleansing practices and beliefs, glove use, and patient load.

Methods: This was a single-masked analysis of resident and transient flora of ophthalmologists before and after patient examination and after handwashing by agar imprints of the dominant hand. Standardized questionnaires were used to collect information concerning subjects' hand cleansing practices and patient load.

Results: Of the 108 cultures, 107 (99.1%) were culture positive, yielding 15 separate organisms. Gram-negative bacilli were the most common transient flora, followed by Gram-positive cocci and fungi. Thirty-five (97.2%) ophthalmologists were culture positive for at least one resident and 8 (22.2%) ophthalmologists were culture positive for at least one transient organism, before patient contact. Regression models showed alcohol-based hand rub use, transient and resident floral load before patient contact, and patient load collectively accounted for 58.7% of the variance in resident floral load after patient contact. Use of alcohol-based hand rubs was associated with a mean resident floral reduction of 324.4 CFUs (95% confidence interval [CI] = 185.4 to 463.5; P < 0.01) and 31.6 CFUs (95% CI = 1.2 to 62.0; P < 0.05) after patient contact and handwashing, respectively. Handwashing with chlorhexidine was a significant predictor for transient floral load after handwashing (unstandardized beta = -17.2; 95% CI = -10.2 to -24.2; P < 0.01).

Conclusions: The extent of contamination with pathogenic organisms after contact with eye outpatients, who have traditionally been perceived as relatively "clean," was of concern. Previously identified risk factors for hand contamination in inpatient settings, such as patient load, only explained a small proportion of variance in microbial load in the ophthalmic outpatient setting.
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http://dx.doi.org/10.1167/iovs.05-0216DOI Listing
October 2005

Retained presumed intraocular cotton fiber after cataract operation: long-term follow-up with in vivo confocal microscopy.

J Cataract Refract Surg 2005 Aug;31(8):1582-7

Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hospital Authority Ophthalmic Services, Hong Kong Special Administrative Region, Hong Kong, China.

Purpose: To evaluate the long-term clinical outcomes in eyes with retained presumed intraocular cotton fibers after cataract surgery.

Setting: Hong Kong Eye Hospital, Hong Kong, The People's Republic of China.

Methods: A retrospective review of 19 eyes with retained presumed intraocular cotton fibers after cataract surgery was performed. Outcome measures were fiber-related complications. In vivo confocal microscopy was performed in eyes with entrapped cotton fibers at the wound site.

Results: The duration of retained presumed cotton fibers ranged from 5 to 110 months (mean 42.3 months). No complications were noted in any of these eyes, including endophthalmitis, persistent uveitis, or corneal endothelial cell loss. In vivo confocal microscopy in eyes with entrapped fibers at the wound site showed normal corneal endothelium morphology with no keratocyte activation or inflammatory response.

Conclusions: Retained presumed fibers after cataract operations are more common than anticipated. In contrast to other organic foreign bodies, these retained fibers appear to be well tolerated. Conservative treatment can be adopted for these fibers as these pose minimal toxicity to the eye.
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http://dx.doi.org/10.1016/j.jcrs.2005.02.036DOI Listing
August 2005

Macular pigment optical density in a Chinese sample.

Curr Eye Res 2005 Sep;30(9):799-805

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, People's Republic of China.

Purpose: Extensive efforts have been devoted to determining the macular pigment optical density (MPOD) in Caucasian subjects. Unfortunately, no such data in ethnic groups with naturally dark irises are currently available. In this study, we report the values in a sample of Chinese subjects.

Methods: The MPOD was measured psychophysically using a densitometer at 0.25 degrees , 0.50 degrees , 1.00 degrees , and 2.00 degrees eccentricity from the foveal center in 92 Chinese subjects.

Results: The spatial profile for the averaged MPOD was approximately exponential in form and showed a decline with age (r = -0.23). Subjects aged below 60 years had significantly higher averaged MPOD than those aged 60 years or above. Significant gender differences, in favor of males, were also found in the middle-age groups.

Conclusions: Our study reports for the first time the MPOD in a Chinese population. Baseline information on MPOD would aid future research in preventive measures against age-related macular degeneration.
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http://dx.doi.org/10.1080/02713680590968439DOI Listing
September 2005

Vitreous VEGF secretion.

Ophthalmology 2005 Aug;112(8):1483; author reply 1483

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http://dx.doi.org/10.1016/j.ophtha.2005.01.025DOI Listing
August 2005

Prevalence, incidence, and progression of myopia of school children in Hong Kong.

Invest Ophthalmol Vis Sci 2004 Apr;45(4):1071-5

Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, Kowloon, Hong Kong, People's Republic of China.

Purpose: To determine the prevalence, incidence, and progression of myopia of Chinese children in Hong Kong.

Methods: A cross-sectional survey was initially conducted. A longitudinal follow-up study was then conducted 12 months later.

Results: A total of 7560 children of mean age 9.33 (95% confidence interval [CI] = 9.11-9.45; range, 5-16) participated in the study. Mean spherical equivalent refraction (SER) was -0.33 D (SD = 11.56; range, -13.13 to +14.25 D). Myopia (SER
Conclusions: The results show that the prevalence and progression of myopia in Hong Kong children was much higher than those previously reported in Western countries. The long-term socioeconomic impact of these findings warrants further studies.
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http://dx.doi.org/10.1167/iovs.03-1151DOI Listing
April 2004

Preoperative ofloxacin.

Ophthalmology 2003 Dec;110(12):2430-1; author reply 2431-2

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http://dx.doi.org/10.1016/j.ophtha.2003.09.010DOI Listing
December 2003
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