Gordon S. K. Yau

Incidence and Risk Factors of Retinopathy of Prematurity From 2 Neonatal Intensive Care Units in a Hong Kong Chinese Population.

PurposeTo determine the incidence and risk factors of retinopathy of prematurity (ROP) in very low birth weight (VLBW) preterm Chinese infants. DesignRetrospective review. MethodsMedical records were reviewed for all neonates screened for ROP between January 2007 and December 2012 in Hong Kong. Screening was offered to VLBW (⩽1500 g) and/or preterm (gestation, ⩽32 weeks) neonates using the Royal College of Ophthalmologists ROP guideline and the International Classification of ROP by 3 pediatric ophthalmologists. Maternal and neonatal covariates were analyzed using univariate and multivariable logistic regression analyses for both ROP and type 1 ROP. ResultsOf the 513 screened infants, the mean gestational age (GA) was 30.0 ± 2.5 weeks and the mean birth weight (BW) was 1232.6 ± 325.2 g. The incidence of ROP and type 1 ROP was 18.5% and 3.7%, respectively. In univariate analysis, a lighter BW, lower GA, blood transfusion, patent ductus arteriosus, nonsteroidal anti-inflammatory drug use, postnatal hypotension, inotropes usage, low Apgar scores, sepsis, mechanical ventilation, supplementary oxygen use, respiratory distress syndrome, anemia, surfactant use, and bronchopulmonary dysplasia were found to be associated with the development of both ROP and type 1 ROP (P < 0.05). In multivariable logistic regression analysis, BW, GA, and intraventricular hemorrhage were significant risk factors for ROP. Preeclampsia and eclampsia were the only protective factors for ROP development on multivariable logistic regression analysis (P = 0.02). ConclusionsIn VLBW preterm Chinese infants, lower GA, lighter BW, and intraventricular hemorrhage were significant risk factors for ROP, whereas preeclampsia and eclampsia were protective.

Prospective Study on Retinal Nerve Fibre Layer Thickness Changes in Isolated Unilateral Retrobulbar Optic Neuritis

Purpose. To investigate the retinal nerve fibre layer (RNFL) thickness after unilateral acute optic neuritis using optical coherence tomography (OCT). Patients and Methods. This prospective cohort study recruited consecutive patients with a first episode of isolated, unilateral acute optic neuritis. RNFL thickness and visual acuity (VA) of the attack and normal fellow eye were measured at presentation and 3 months in both the treatment and nontreatment groups. Results. 11 subjects received systemic steroids and 9 were treated conservatively. The baseline RNFL thickness was similar in the attack and fellow eye (P ≥ 0.4). At 3 months, the attack eye had a thinner temporal (P = 0.02) and average (P = 0.05) RNFL compared to the fellow eye. At 3 months, the attack eye had significant RNFL thinning in the 4 quadrants and average thickness (P ≤ 0.0002) compared to baseline. The RNFL thickness between the treatment and nontreatment groups was similar at baseline and 3 months (P ≥ 0.1). Treatment offered better VA at 3 months (0.1 ± 0.2 versus 0.3 ± 0.2 LogMAR, P = 0.04). Conclusion. Generalized RNFL thinning occurred at 3 months after a first episode of acute optic neuritis most significantly in the temporal quadrant and average thickness. Visual improvement with treatment was independent of RNFL thickness.

Incidence and Risk Factors for Retinopathy of Prematurity in Multiple Gestations: A Chinese Population Study

AbstractTo determine the incidence and risk factors of retinopathy of prematurity (ROP) among new-born Chinese infants of multiple gestations.A retrospective review of medical records was performed for all neonates of multiple gestations screened for ROP between January 2007 and December 2012 in 2 neonatal intensive care units in Hong Kong. Screening was offered to very low birth weight (VLBW; ⩽1500 g) and/or preterm (gestation ⩽32 weeks) neonates using the Royal College of Ophthalmologists ROP guideline and the International Classification of ROP by 3 pediatric ophthalmologists. Maternal and neonatal covariates were analyzed using univariate and multivariate regression analyses for both ROP and Type 1 ROP.A total of 153 Chinese infants of multiple gestations were included in the study. The mean gestational age (GA) was 30.8 ± 2.4 weeks and the mean birth weight (BW) was 1284.8 ± 267.4 g. The incidence of ROP and Type 1 ROP was 11.8% and 3.9%, respectively. On univariate analysis, younger GA, lighter birth weight, postnatal hypotension, inotropes use, bronchopulmonary disease, and intraventricular hemorrhage were common independent risk factors for the development of ROP and Type 1 ROP (all P ⩽ 0.04). On multivariate analysis, younger GA, surfactant use, invasive mechanical ventilation, higher mean oxygen concentration, thrombocytopenia, intraventricular hemorrahage, total parental nutrition, and hypoglycemia were significant risk factors for ROP. For Type 1 ROP, there were no significant dependent risk factors.In preterm Chinese infants born from multiple gestations, prematurity, lighter weight, postnatal hypotension, inotropes use, bronchopulmonary dysplasia, and an intraventricular hemorrhage were common independent risk factors for the development of ROP and Type 1 ROP.

Retinal nerve fiber layer thickness in myopic, emmetropic, and hyperopic children.

AbstractThe purpose of this study was to investigate the peripapillary retinal nerve fiber layer (RNFL) thickness in myopic, emmetropic, and hyperopic children using optical coherence tomography.Two-hundred one right eyes of subjects aged 4 to 18 years were divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D), emmetropes (≥−1.0 to ⩽+1.0 D), and hyperopes (>+1.0 D). The RNFL was correlated with age, spherical equivalent, and axial length. The RNFL was compared between the 3 groups before and after age adjustment.The RNFL was thickest in the hyperopic group (107.2 ± 10.13 &mgr;m, n = 73), followed by the emmetropic group (102.5 ± 9.2 &mgr;m, n = 61), and then the myopic group (95.7 ± 10.3, n = 67) (all P < 0.0001). The myopic group (9.6 ± 3.9 years) was significantly older than the emmetropic (6.9 ± 2.7 years) and hyperopic (6.5 ± 1.9 years) groups (both P < 0.0001). When adjusted for age, myopes had a thinner RNFL than the other 2 groups (all P < 0.0001), but there was no RNFL thickness difference between the emmetropic and hyperopic groups (P > 0.05). A thinner RNFL was associated with an older age (r = −0.4, P < 0.0001), a more myopic spherical equivalent (r = 0.5, P < 0.0001), and a longer axial length (r = −0.4, P < 0.0001) on Pearson correlation analysis.The apparently thicker RNFL in hyperopic and emmetropic children was attributed to their younger age as compared with their myopic counterparts. When adjusted for age, only myopia was associated with a thinner RNFL, with emmetropic and hyperopic children having equal RNFL thicknesses. Advancing age, a more myopic spherical equivalent, and a longer axial length were associated with a thinner RNFL in children.

Differences in Risk Factors for Retinopathy of Prematurity Development in Paired Twins: A Chinese Population Study

Purpose. To determine the differences in risk factors for retinopathy of prematurity (ROP) in paired twins. Methods. A retrospective medical record review was performed for all paired twins screened for ROP between 2007 and 2012. Screening was offered to very low birth weight (≤1500 grams) and preterm (≤32 weeks) neonates. Twins 1 and 2 were categorized based on the order of delivery. Maternal and neonatal covariates were analyzed using univariate and multivariate regression analyses for both ROP and Type 1 ROP. Results. In 34 pairs of Chinese twins, the mean gestational age (GA) was 30.2 ± 2.0 weeks. In Twin 1, smaller GA (OR = 0.44, P = 0.02), higher mean oxygen concentration (OR = 1.34, P = 0.03), presence of thrombocytopenia (OR = 1429.60, P < 0.0001), and intraventricular hemorrhage (OR = 18.67, P = 0.03) were significant risk factors for ROP. For Twin 2, a smaller GA (OR = 0.45, P = 0.03) was the only risk factor. There were no significant risk factors for ROP in Twin 1 or Twin 2 on multivariate analysis. Conclusion. In Chinese twin pairs, smaller GA was the only common risk factor for ROP while Twin 1 was more susceptible to the postnatal risks for ROP.

Risk Factors for Retinopathy of Prematurity in Extremely Preterm Chinese Infants

AbstractTo investigate the incidence and risk factors of retinopathy of prematurity (ROP) and Type 1 ROP in extremely preterm Chinese infants.A retrospective review of medical records was performed of all extremely preterm neonates (gestational age, GA ⩽ 28 weeks) screened for ROP from 2007 to 2012 at an ophthalmology centre in Hong Kong. Thirty-three maternal and neonatal covariates were analyzed using univariate and multivariate regression analyses for both ROP and Type 1 ROP.The mean gestational age (GA) was 26.4 ± 1.3 weeks and the birth weight (BW) was 855.0 ± 199.0 g. The incidence of ROP development was 60.7% and 16.2% for Type 1 ROP. On univariate analysis, 6 risk factors were identified for ROP development including: lighter BW; lower GA; postnatal hypotension; inotrope use; surfactant use; and invasive mechanical ventilation (all P ⩽ 0.01). On multivariate analysis, neonatal congenital heart disease and greater GA were protective factors for ROP development (P ⩽ 0.04). On the other hand, 4 risk factors were associated with Type 1 ROP development in univariate analysis, including: lower GA, lighter BW, multiple pregnancies, and invasive mechanical ventilation (all P ⩽ 0.02); while there was no significant risk factors on multivariate analysis.A lighter BW and lower GA were the only common independent risk factors for both ROP and Type 1 ROP while neonatal congenital heart disease and greater GA were the protective factors against ROP.

Cross-sectional study of the retinal nerve fiber layer thickness at 7 years after an acute episode of unilateral primary acute angle closure

Abstract The purpose of this article is to investigate the long-term retinal nerve fiber layer (RNFL) status and determinants of RNFL thinning after an episode of unilateral primary acute angle closure (AAC). This cross-sectional study analyzed the medical records of consecutive patients with a single episode of unilateral AAC from 1999 to 2009 in Hong Kong. The peripapillary RNFL thickness was correlated with age, gender, presenting intraocular pressure (IOP), time to laser iridotomy, time to cataract extraction, follow-up duration, as well as the last IOP, vertical cup-to-disc ratio (CDR), and vision. The fellow uninvolved eye was used as a proxy comparison of RNFL loss in the attack eye. In 40 eligible patients, the mean age was 68.3 ± 8.7 years with a male-to-female ratio of 1:7. The mean presenting IOP was 49.2 ± 14.0 mm Hg and the time from presentation to laser iridotomy was 6.7 ± 6.9 days. Forty percent of subjects received a cataract extraction at 3.2 ± 2.9 years after the attack. The last IOP, CDR, and LogMAR vision were 16.0 ± 3.8 mm Hg, 0.6 ± 0.2, and 0.6 ± 0.6 LogMAR units, respectively, at 7.9 ± 2.4 years. The RNFL thickness in the attack eye (69.2 ± 19.1 &mgr;m) was 25.2 ± 17.9% thinner than the fellow eye (93.0 ± 17.8 &mgr;m) at 7.5 ± 2.9 years post-AAC. Using univariate analysis, the last vertical CDR (odds ratio [OR] = 17.2, P = 0.049) and LogMAR visual acuity (VA) (OR = 6.6, P = 0.03) were the only significant predictors for RNFL thinning whereas none of the other covariates showed significant associations (P > 0.1). At 7.5 years following unilateral AAC, the RNFL thickness was 25% thinner than the fellow eye. CDR enlargement and poor VA were the only significant predictors for RNFL loss.

Relationship between Outer Retinal Layers Thickness and Visual Acuity in Diabetic Macular Edema

Purpose. To investigate the correlation of outer retinal layers (ORL) thickness and visual acuity (VA) in patients with diabetic macular edema (DME). Methods. Consecutive DME patients seen at the Retina Clinic of The University of Hong Kong were recruited for OCT assessment. The ORL thickness was defined as the distance between external limiting membrane (ELM) and retinal pigment epithelium (RPE) at the foveal center. The correlation between total retinal thickness, ORL thickness, and vision was calculated. Results. 78 patients with DME were recruited. The mean age was 58.1 years (±11.5 years) and their mean visual acuity measured with Snellen chart was 0.51 (±0.18). The correlation coefficient between total retinal thickness and visual acuity was 0.34 (P < 0.001) whereas the correlation coefficient was 0.65 between ORL thickness and visual acuity (P < 0.001). Conclusion. ORL thickness correlates better with vision than the total retinal thickness. It is a novel OCT parameter in the assessment of DME. Moreover, it could be a potential long term visual prognostic factor for patients with DME.

The Anterior Chamber Depth and Retinal Nerve Fiber Layer Thickness in Children

Purpose. To investigate the correlation of anterior chamber depth (ACD) with the peripapillary retinal nerve fiber layer (RNFL) thickness, age, axial length (AL), and spherical equivalent in children. Subjects. Consecutive subjects aged 4 to 18 were recruited. Visually disabling eye conditions were excluded. Only the right eye was included for analysis. The ACD was correlated with RNFL thickness, age, spherical equivalent, and AL for all subjects. Subjects were then divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D), emmetropes (≥−1.0 to ≤+1.0 D), and hyperopes (>+1.0 D). The ACD was compared among the 3 groups before and after age adjustment. Results. In 200 subjects (mean age 7.6 ± 3.3 years), a deeper ACD was correlated with thinner global RNFL (r = −0.2, r 2 = 0.06, P = 0.0007), older age (r = 0.4, r 2 = 0.1, P < 0.0001), myopic spherical equivalent (r = −0.3, r 2 = 0.09, P < 0.0001), and longer AL (r = 0.5, r 2 = 0.2, P < 0.0001). The ACD was deepest in myopes (3.5 ± 0.4 mm, n = 67), followed by emmetropes (3.4 ± 0.3, n = 60) and then hyperopes (3.3 ± 0.2, n = 73) (all P < 0.0001). After age adjustment, myopes had a deeper ACD than the other 2 groups (all P < 0.0001). Conclusions. In children, a deeper ACD was associated with thinner RNFL thickness, older age, more myopic spherical equivalent, and longer AL. Myopes had a deeper ACD than emmetropes and hyperopes.

MicroPulse Laser Trabeculoplasty for the Treatment of Open-Angle Glaucoma.

AbstractThe aim of the study was to investigate the safety and efficacy of using MLT in the treatment of open-angle glaucoma (OAG).This prospective cohort included subjects ≥18 years of age with OAG, defined as the open angle on gonioscopy with glaucomatous optic neuropathy evident from optical coherence tomography. Subjects with IOP < 21 mm Hg were classified as normal tension glaucoma and those with IOP ≥21 mm Hg were classified as primary open-angle glaucoma. Those with angle closure, secondary glaucoma, prior laser trabeculoplasty, use of systemic IOP-lowering medications, corneal pathologies, follow-up <6 months, recent intraocular surgery, or only 1 functional eye were excluded. A single session of unilateral MLT treatment was delivered using a 577 nm diode laser to 360° of the trabecular meshwork to reduce IOP or medication load. Medications were titrated up or down at 1 month after laser to achieve a 25% IOP reduction from presentation or an IOP <18 mm Hg, whichever was lower. The following were compared using the Repeated Measures ANOVA with Bonferronis Multiple Comparison Test: IOP (on presentation, pre-MLT, day 1, 1 week, 1 month, 3 months, and 6 months after MLT) and the number of medications (pre-MLT, 3 months, and 6 months after MLT). After 6 months, responders with initial success to MLT (IOP reduction ≥20% at 1 month) received treatment in the fellow eye.In 48 subjects with OAG, the mean number of MLT shots applied was 120.5 ± 2.0 shots using a mean energy of 1000 mW per shot. Only 7.5% had a mild, self-limiting anterior uveitis postlaser with no change in the Snellen visual acuity at 6 months (Ps > 0.5). The IOP and number of medications were significantly reduced at all time intervals following MLT compared to the pre-MLT level (Ps < 0.0001). At 6 months, the IOP was reduced by 19.5% in addition to a 21.4% reduction in medication compared to pretreatment levels. The MLT success rate was 72.9%. During the first 6 months only 2.1% required a repeated laser trabeculoplasty.MLT was effective in reducing IOP and medications in OAG with minimal postlaser inflammation and low failure rate at 6 months following laser.