The Omicron variant of COVID-19 and its association with croup in children: a single-centre study in Hong Kong.

INTRODUCTION: The fifth wave of the coronavirus disease 2019 (COVID-19) pandemic in Hong Kong was dominated by the Omicron variant, which may cause more upper airway involvement in children. This study was performed to identify any associations between the Omicron variant of COVID-19 and croup in children. METHODS: This retrospective study reviewed the electronic medical records of patients admitted to Tuen Mun Hospital in Hong Kong from 1 January 2018 to 31 March 2022 under the diagnostic code for croup (J05.0 in the International Classification of Diseases 10th Edition). Patients were categorised into three groups according to their admission periods, namely, non-COVID-19, COVID-19-pre-Omicron, and COVID-19-Omicron groups. Disease associations and severity were compared according to incidence, Westley Croup Score, length of hospital stay, medication use, respiratory support, and intensive care unit admissions. RESULTS: The COVID-19 incidence among patients with croup was significantly higher in the COVID-19-Omicron group than in the COVID-19-pre-Omicron group (90.0% vs 2.0%; P<0.001). Compared with patients in the COVID-19-pre-Omicron and non-COVID-19 groups, patients in the COVID-19-Omicron group also had a higher Westley score (moderate and severe disease in the COVID-19-Omicron group: 56.7%; COVID-19-pre-Omicron group: 22.0%, P=0.004; non-COVID-19 group: 24.8%, P<0.001), longer median hospital stay (COVID-19-Omicron group: 3.00 days; COVID-19-pre-Omicron group: 2.00 days, P<0.001; non-COVID-19 group: 2.00 days, P=0.034), and higher mean dexamethasone requirement (COVID-19-Omicron group: 0.78 mg/kg; COVID-19-pre-Omicron group: 0.49 mg/kg, P<0.001; non-COVID-19 group: 0.58 mg/kg, P=0.001). CONCLUSION: The Omicron variant of COVID-19 is associated with croup and can cause more severe disease in Hong Kong children.

Epidemiology and risk factors for severe respiratory syncytial virus infections requiring pediatric intensive care admission in Hong Kong children.

PURPOSE: Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infection in young children. However, there are limited data on severe RSV infection requiring pediatric intensive care unit (PICU) admission. This retrospective study described features of RSV-associated PICU admissions in Hong Kong and investigated factors for mortality and duration of PICU stay. METHODS: Children with laboratory-confirmed RSV infection and admitted to the PICUs of all eight government hospitals in Hong Kong between January 2009 and June 2011 were identified from computerized auditing systems and PICU databases. RSV in respiratory samples was detected by direct immunofluorescence and/or viral culture. The relationships between mortality and PICU duration and demographic and clinical factors were analyzed. RESULTS: A total of 118 (2.4 %) PICU admissions were identified among 4,912 RSV-positive pediatric cases in all hospitals. Sixty-five (55.6 %) patients were infants. PICU admissions were higher between October and March. Eight (6.8 %) patients died, but only two were infants. RSV-associated mortality was related to prior sick contact, presence of older siblings, neurodevelopmental conditions, chromosomal and genetic diseases, and bacterial co-infections, but none was significant following logistic regression analyses (odds ratio 9.36, 95 % confidence interval 0.91-96.03 for prior sick contact, p = 0.060). Chronic lung disease was the only risk factor for the duration of PICU admission (ß = 0.218, p = 0.017). CONCLUSIONS: The majority of RSV-infected children do not require PICU support. There is winter seasonality for RSV-associated PICU admission in Hong Kong. Prior sick contact is the only risk factor for RSV-associated mortality, whereas the presence of chronic lung disease is associated with longer PICU stay. The current risk-based approach of RSV prophylaxis may not be effective in reducing severe RSV infections.

Long-term outcome of intravitreal anti-vascular endothelial growth factor therapy with bevacizumab or ranibizumab as primary treatment for subfoveal myopic choroidal neovascularization.

PURPOSE: To evaluate the long-term efficacy of intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy as primary treatment for subfoveal myopic choroidal neovascularization (CNV). METHODS: In all, 37 treatment-naïve eyes of 37 patients with subfoveal myopic CNV who received intravitreal bevacizumab (n=22) or ranibizumab (n=15) injections with at least 2 years of follow-up were reviewed. All eyes received initial three loading doses of anti-VEGF at monthly intervals and retreatment was performed in persistent or recurrent CNV. Multivariate regression analyses were performed to determine the prognostic factors for visual outcome. RESULTS: The mean age was 57.3 years and the mean refractive error was -11.7 D. For all eyes, the mean logMAR best-corrected visual acuity improved from 0.86 (20/145) at baseline to 0.48 (20/60) at 2 years (P<0.001). The mean visual improvement for the bevacizumab and ranibizumab groups at 2 years was 2.8 and 5.1 lines, respectively (P=0.073). There was no significant difference in the proportion of eyes having visual gain of three or more lines or visual loss of three or more lines between the two groups. The mean number of injections was 3.8 for both bevacizumab and ranibizumab groups. Multivariate analyses showed that eyes with higher myopic refractive error were less likely to have visual gain after treatment (P=0.043), while size of CNV was negatively correlated with mean change in vision (P=0.046). CONCLUSIONS: Intravitreal anti-VEGF therapy resulted in long-term visual improvement in myopic CNV. The treatment efficacy in terms of visual gain and number of retreatment appeared to be similar between bevacizumab and ranibizumab.

Comparisons of anterior segment biometry between Chinese and Caucasians using anterior segment optical coherence tomography.

PURPOSE: To compare anterior segment parameters between eyes of Chinese and Caucasians using anterior segment optical coherence tomography and to evaluate the association between these parameters and anterior chamber angle width between the two ethnic groups. METHODS: 60 Chinese and 60 Caucasians, 30 with open angles and 30 with narrow angles (defined as Shaffer grade < or =2 in > or =3 quadrants during dark room gonioscopy) in each group, were consecutively enrolled. One eye of each subject was randomly selected for imaging in a completely darkened room. Measurements, including anterior chamber depth (ACD), scleral spur-to-scleral spur distance (anterior chamber width (ACW)), anterior chamber angle width, iris convexity and iris thickness, were compared between the groups. The associations between angle opening distance and biometric measurements were evaluated with univariate and multivariate regression analyses. RESULTS: There were no differences in age, axial length, anterior chamber angle measurements, pupil diameter and iris convexity between Chinese and Caucasians in both open-angle and narrow-angle groups. However, the ACD and ACW were smaller and the iris was thicker in Chinese. In the multivariate analysis, the ACD was the most influential biometric parameter for angle opening distance in both Chinese and Caucasians. After adjusting the effects of axial length, age and sex, ACD and ACW were significantly smaller in Chinese. CONCLUSIONS: Chinese eyes had smaller ACD, smaller ACW and greater iris thickness than Caucasians. ACD was the most influential parameter in determining the angle width in both ethnic groups.

Surgical outcome of single-staged three horizontal muscles squint surgery for extra-large angle exotropia.

PURPOSE: To report the surgical outcomes of 24 patients undergoing single-staged three horizontal muscles squint surgery for extra-large angle exotropia. PATIENTS AND METHODS: Prospective case series of 24 consecutive patients with primary exotropia>60 prism diopters (PD) at distant and underwent single-staged three horizontal muscles squint surgery from 2003 to 2006. Surgery consisted of bilateral lateral rectus recession of 9.0 mm for 50 PD exotropic correction. For every 5 PD remaining angle exceeding 50 PD, we additionally performed 1.0 mm of unilateral medial rectus resection. The mean follow-up period was 15.8 months (range 6.0-38.0 months; SD 9.5 months). RESULTS: The mean age at surgery was 31.2 years old (range 7-78 years old, SD 18.2 years old). The mean distant preoperative deviation was 71.3 PD (range 60-85 PD, SD 7.7 PD). No limitation of eye movement or diplopia was found. The success rate was higher in the intermittent group (88.2%) than the constant group (42.9%) (P=0.02) and in cases with preoperative deviation of <80 PD (84.2%) compared with those with deviation>or=80 PD (40.0%) (P=0.042). CONCLUSION: Measurement of preoperative deviation and the surgery for extra-large angle exotropia made management of this condition difficult. Single-staged three horizontal muscles squint surgery can be one of the options. Further researches on management of exotropia of >80 PD are warranted.

Unilateral ptosis correction with mersilene mesh frontalis sling in infants: thirteen-year follow-up report.

PURPOSE: To assess surgical, visual, refractive, and aesthetic outcomes 13 years after mersilene mesh frontalis sling (MMFS) operation for severe unilateral congenital ptosis performed in 10 infants before 1 year of age. METHODS: Longitudinal follow-up of an interventional case series by structured ocular examinations, external photographs, and questionnaire-based interviews. RESULTS: Mean age at surgery was 6.9+/-2.7 months. After a mean follow-up of 13.0+/-0.6 years, one patient (10%) had recurrent ptosis with the upper lid 2 mm below the superior limbus at 3 months postoperatively. Best-corrected visual acuities were within two Snellen lines between the two eyes in all patients. Astigmatic errors were 1.20+/-1.00 D and 1.10+/-1.70 D between operated and unoperated eyes. Four patients had 2 mm lid lag on down-gaze and one of them had 2 mm lagophthalmos. Mean satisfaction scores (scale of 1 to 100) for lid position, cosmesis, function, and to the procedure were 83.3+/-11.8, 77.0+/-22.9, 89.4+/-5.5, and 86.8+/-6.3, respectively. No case of overcorrection, sling extrusion, stitch granuloma, or exposure keratopathy was noted. CONCLUSIONS: In view of the low recurrence rate (10%) and absence of serious complication or need for revision after 13 years, the use of MMFS seems effective and feasible in infants less than 1 year old. Achieving compatible long-term stability, satisfactory aesthetic, and visual outcomes, MMFS may offer an alternative to delaying operations for autogenous fascia lata harvesting in infants requiring early ptosis correction.

Multifocal electroretinography changes in patients on ethambutol therapy.

PURPOSE: To evaluate the multifocal electroretinography (mfERG) changes in patients on ethambutol therapy. METHODS: A cross-sectional observational study of 17 visually asymptomatic patients receiving antituberculosis therapy with ethambutol. Patients underwent complete ophthalmic examination and mfERG recordings. The first-order mfERG N1 and P1 response amplitudes and implicit times of six concentric rings were analysed and compared with 17 normal age-similar controls. Correlation analyses were performed between the patients' mfERG parameters with parameters of ethambutol usage (daily dose of ethambutol per body weight, duration of ethambutol therapy, cumulative dose of ethambutol, and cumulative dose of ethambutol per body weight). RESULTS: The mean duration of ethambutol therapy was 3.6 months (range: 2-9 months) and the mean daily dose per body weight was 13.2 mg/kg/day. Analysis of response amplitude measures showed no significant difference in the mfERG N1 and P1 response amplitudes between the ethambutol and control groups at all ring eccentricities (P>0.05). For implicit times, there were significant delays in the mfERG P1 implicit times of rings 4-6 in the ethambutol group compared with controls (P=0.012 to P=0.041). Correlation analyses showed no significant correlation between the mfERG and ethambutol parameters (P>0.05). CONCLUSIONS: The mfERG findings suggested that visually asymptomatic patients receiving ethambutol therapy might have localized mild electrophysiological changes involving the peripheral macula. These changes might be related to localized alteration of metabolism or physiological changes associated with ethambutol therapy.

Residual torticollis in patients after strabismus surgery for congenital superior oblique palsy.

AIM: To study postoperative residual vertical deviation and abnormal head posture (AHP) after surgical treatment for congenital superior oblique palsy (SOP). METHOD: Children with both SOP and AHP who underwent extraocular muscle surgery for correction of AHP were recruited. The patients received complete ophthalmic and orthopaedic examinations. Residual AHP was classified according to severity of face turn, head tilt and chin elevation. RESULTS: Thirty-two children with mean age at operation of 82.6 months were recruited, with mean follow-up of 37.9 months. Of these children, 65.6% had a postoperative vertical deviation of less than three prism dioptres. In addition, 34.4% patients had resolved (0 degrees ), 34.4% had mild (1 degrees -10 degrees ), and 31.3% had significant residual torticollis (>10 degrees ). Of the patients with significant residual torticollis, 33.3% had ocular causes. The mean age at operation for the patients with residual torticollis (95.9 months) was older than those without torticollis (79.9 months) (p = 0.018). Residual torticollis was found to be related to sternocleidomastoid muscle tightness (p = 0.013). CONCLUSION: The success rate for eliminating significant AHP after strabismus surgery for patients with congenital SOP was 68.8%. Early surgery was associated with a better outcome. Association was also found between sternocleidomastoid tightness and AHP. A multidisciplinary approach is recommended in the management of torticollis as ophthalmic and orthopaedic comorbidities can coexist.

Predictors of atypical birefringence pattern in scanning laser polarimetry.

AIM: To evaluate predictors of atypical birefringence patterns (ABP) observed in scanning laser polarimetry. METHODS: A total of 179 eyes from 82 normal subjects and 97 glaucoma patients were included. The retinal nerve fibre layer in each eye was imaged sequentially with GDx variable corneal compensation (VCC) and GDx enhanced corneal compensation (ECC) (Carl Zeiss Meditec, Dublin, California). The associations between the typical scan score (TSS) and age, axial length, spherical error, parapapillary atrophy (PPA) and visual-field mean deviation (MD) were evaluated with univariate and multivariate regression analyses. RESULTS: 23.5% (42/179) and 5.0% (9/179) of subjects had ABP (TSS<80) with GDx VCC and GDx ECC, respectively. For both GDx VCC and ECC, the TSS was significantly correlated with age, axial length, spherical error and PPA, but not with visual-field MD. After adjusting the effect of covariates, the axial length/spherical error and PPA were significantly associated with GDx VCC TSS, whereas the axial length/spherical error was the only predictor for GDx ECC TSS. Myopic eyes were more likely to develop ABP in both GDx VCC and ECC. CONCLUSIONS: Axial length or spherical error is a significant predictor for ABP with both GDx VCC and GDx ECC. Caution should be exercised in interpreting the results of scanning laser polarimetry in eyes with a long axial length or myopia.

Topiramate and asymptomatic ocular angle narrowing: a prospective pilot study.

PURPOSE: To investigate whether subclinical ciliochoroidal effusion and resulting asymptomatic angle narrowing occurs in patients taking topiramate, by ultrasound biomicroscopy (UBM). METHODS: Chinese patients aged 18-75 years for whom topiramate was indicated were recruited. Examinations including UBM were performed before and 4 weeks after commencement of topiramate. RESULTS: In this pilot of 20 eyes of 20 patients, there were no statistically significant changes in the angle parameters noted on gonioscopy or UBM, including anterior chamber depth, angle-opening distance at 500 mum, trabecular ciliary process distance, trabecular-iris angle, and scleral thickness. CONCLUSION: Short-term use of topiramate does not induce asymptomatic angle narrowing.

Quantitative assessment of optic nerve head morphology and retinal nerve fibre layer in non-arteritic anterior ischaemic optic neuropathy with optical coherence tomography and confocal scanning laser ophthalmoloscopy.

BACKGROUND/AIMS: To compare the optic disc parameters between patients with non-arteritic anterior ischaemic optic neuropathy (NAION) and normal controls, using optical coherence tomography (OCT) and Heidelberg Retinal Tomograph III (HRT), and to evaluate the structure-function relationship in NAION eyes. METHODS: Both eyes of 22 patients with typical unilateral NAION of > or =6 months' duration and 52 eyes from 52 randomly selected normal subjects underwent Humphrey visual field (HVF) examination and measurement of optic disc and retinal nerve fibre layer thickness (RNFLT). RESULTS: For the NAION-affected eyes, NAION fellow eyes and normal controls, the ocular magnification-corrected OCT disc areas were respectively 1.849 (SD 0.343) mm(2), 1.809 (0.285) mm(2) and 1.964 (0.386) mm(2); the cup areas were 0.246 (0.187) mm(2), 0.172 (0.180) mm(2) and 0.469 (0.332) mm(2). On HRT, the disc areas were 2.11 (0.38) mm(2), 2.06 (0.40) mm(2) and 2.16 (0.42) mm(2); and the cup areas were 0.28 (0.34) mm(2), 0.25 (0.18) mm(2) and 0.48 (0.32) mm(2). On both OCT and HRT, the cup areas and cup-disc area ratios (CDAR) of both eyes of NAION patients were significantly smaller than controls (p< or =0.01), but the disc areas were not (p> or =0.21). There was a significant correlation between HVF mean deviation and OCT RNFLT (r = 0.44, p = 0.04) but not with HRT RNFLT (p = 0.30) in NAION-affected eyes. CONCLUSION: NAION patients have smaller optic cups and CDARs in both eyes compared with controls. A larger sample size is necessary to demonstrate if disc size affects the risk of developing NAION. The NAION-affected eyes' OCT RNFLT correlated with HVF mean deviation but the HRT RNFLT did not.

Randomised controlled trial on the effectiveness of lidocaine gel vs tetracaine drops as the sole topical anaesthetic agent for primary pterygium surgery.

PURPOSE: To determine the effectiveness of lidocaine 2% gel vstetracaine 1% drops in primary pterygium surgery. METHODS: This was a prospective, randomised controlled trial. Forty consecutive patients who had primary pterygium underwent surgical excision of primary pterygium and mitomycin C. Patients were randomised into two groups. Group 1 received tetracaine 1% drops and solcoseryl eye gel (Solco Basel AG, Switzerland). Group 2 received xylocaine 2% gel (lidocaine hydrochloride 2% gel, AstraZeneca, Sweden) topically and normal saline drops 0.9%. Additional tetracaine drops were given to patients who experienced pain preoperatively. The primary outcome was the pain experienced during and after surgery. Immediately after the operation, pain and discomfort scores were assessed by the patients and doctor using a 10-point linear analogue scale. The stages of the operation were divided into the following: stage 1-first incision, stage 2-pterygium body excision, stage 3-conjunctival suturing, and stage 4-immediate postoperative after patching. RESULTS: There was no statistically significant difference in the mean pain scores experienced during pterygium excision (3.03+/-2.35 for the lidocaine group and 3.98+/-2.18 for the tetracaine group). However, for stage 3, there was a statistically significant difference in mean pain scores experienced during closure (P=0.03) (0.47+/-0.84 for the lidocaine gel group and 1.43+/-1.66 for the tetracaine group), with patients of group 2 experienced less pain. The mean number of additional drops required by the eyes in lidocaine gel group was also significantly (0.16+/-0.11) less than the tetracaine group (0.67+/-0.09, P=0.001). CONCLUSIONS: Topical administration of lidocaine 2% gel or tetracaine 1 % drops are both effective anaesthetic agents for primary pterygium surgery and mitomycin C. However, lidocaine gel is superior to tetracaine eye drops and its application is more convenient with a less frequent application and a sustained duration of action.

Quantitative assessment of lens opacities with anterior segment optical coherence tomography.

AIM: To evaluate the reliability of lens density measurement with anterior segment optical coherence tomography (OCT) and its association with the Lens Opacity Classification System Version III (LOCS III) grading. METHODS: Fifty-five eyes from 55 age-related cataract patients were included. One eye from each subject was selected at random for lens evaluation. After dilation, lens photographs were taken with a slit lamp and graded against the LOCS III standardised condition. Anterior segment OCT imaging was performed on the same eyes with a high-resolution scan. The association between the anterior segment OCT nucleus density measurement and LOCS III nuclear opalescence (NO) and nuclear colour (NC) scores was evaluated with the Spearman correlation coefficient. Anterior segment OCT measurement precision, coefficient of variation (CVw), and intraclass correlation coefficient (ICC) were calculated. RESULTS: The mean NO and NC scores were 3.39 (SD 1.10) and 3.37 (SD 1.27), respectively. Significant correlations were found between anterior segment OCT nuclear density measurements and the LOCS III NO and NC scores (r = 0.77 and 0.60, respectively, both with p<0.001). The precision, CVw and ICC of anterior segment OCT measurement were 2.05 units, 4.55% and 0.98, respectively. CONCLUSION: Anterior segment OCT nucleus density measurement is reliable and correlates with the LOCS III NO and NC scores.

A novel mutation in CRYBB2 responsible for inherited coronary cataract.

PURPOSE: To study the molecular pathogenesis of a Chinese family with coronary form of cataract. METHODS: One Chinese three-generation family with inherited coronary cataract phenotype was recruited. Five affected and seven unaffected family members attended our study. Genome-wide linkage analysis was applied to map the disease loci, and two candidate genes from a locus on chromosome 1 and a locus on chromosome 22 were sequenced for mutation identification. Software at the Expasy proteomics server was utilized to predict the mutation effect on proteins. RESULTS: Whole genome linkage analysis indicated some regions on chromosome 1, 10, and 22, with LOD score values greater than 1. Within these loci, the GJA8 and CRYBB2 genes, located in the two loci with the highest LOD score of 1.51 on chromosomes 1 and 22, respectively, were sequenced. A novel mutation c.92C>G in exon 2 of CRYBB2 causing S31W was identified in all five patients. It was not found in 95 unrelated controls. This missense sequence alteration likely enhanced the local solubility. Around the mutation site, a lipocalin signature motif was predicted by ScanProsite. CONCLUSIONS: A novel disease-causing mutation S31W in CRYBB2 was identified in a Chinese cataract family. It is the first reported mutation for coronary cataract. Functional characterization should be carried out to evaluate the biological effects of this mutant.

Surgically induced astigmatism in phacoemulsification, pars plana vitrectomy, and combined phacoemulsification and vitrectomy: a comparative study.

PURPOSE: To study the surgically induced astigmatism (SIA) in combined phacoemulsification and vitrectomy, and compare with that when either procedure is performed alone. METHODS: This is a prospective comparative interventional trial comprising of 60 eyes of 60 consecutive patients with cataract and/or vitreo-retinal pathology. They were divided equally into three groups based on the type of procedure: Group A, phacoemulsification alone group, using a 3.0-3.2 mm wide unsutured sclero-corneal tunnel incision at 1.0 mm post-limbus at 10 o'clock; Group B, par plana vitrectomy alone group, using three sclerotomies at 3.5 mm post-limbus at 2, 8, and 10 o'clock (right eye) or at 2, 4, and 10 o'clock (left eye) positions; and Group C, combined phacoemulsification and pars plana vitrectomy group. Main outcome measures were the amplitude (K-induced) and the axis of SIA calculated by rectangular coordinate method using the Holladay-Cravy-Koch formula. RESULTS: The mean K-induced amplitudes were 0.19+/-0.14 D, 0.17+/-0.11 D, and 0.23+/-0.19 D for groups A, B, and C, respectively. The range of K-induced amplitudes for the entire cohort was 0.00-0.77 D. No overall statistically significant differences in the pre- and postoperative topographic astigmatism amplitudes and the K-induced between groups A, B, and C were found (all P>0.05). Minor shifts, of doubtful clinical significance, in the axes of SIA were present. CONCLUSIONS: Combined phacoemulsification and pars plana vitrectomy does not induce significant astigmatic change per se, and its amount is similar to that when either procedure is performed alone.

Effects of the duration of initial oral corticosteroid treatment on the recurrence of inflammation in Vogt-Koyanagi-Harada disease.

PURPOSE: To evaluate the effects of the duration of oral corticosteroid treatment on the recurrence of inflammation in Vogt-Koyanagi-Harada (VKH) disease. METHODS: Retrospective analysis of 35 VKH patients who received oral corticosteroid during the first attack of VKH with a minimum follow-up of 6 months. Patients were divided into two groups on the basis of the oral corticosteroid treatment duration of less than 6 months or 6 months or more. Kaplan-Meier survival and Cox-regression analyses were carried out to compare the recurrence rates of inflammation in the two groups. RESULTS: The mean age of onset was 42.5 years and the mean follow-up duration was 3.6 years. During the follow-up period, 10 (58.8%) of the 17 patients who received oral corticosteroid for less than 6 months compared with 2 (11.1%) of the 18 patients who had treatment for 6 months or more developed recurrence of inflammation (P=0.003). Cox-regression analysis showed that the duration of oral corticosteroid treatment for less than 6 months was the only significant risk factor for recurrence of VKH after adjustment for age, gender, and the initial dosage of oral corticosteroid treatment (adjusted odds ratio=8.8, P=0.008). Patients who received oral corticosteroid treatment for less than 6 months were also more likely to have one eye with visual acuity of 20/200 or worse (P=0.016). CONCLUSIONS: Early withdrawal of oral corticosteroid is associated with increased risk of recurrence of VKH and worse visual prognosis. Oral corticosteroid should be tapered off slowly and maintained for at least 6 months for the treatment of acute VKH.

Correlation of previous acute angle-closure attack with extent of synechial angle closure in chronic primary angle-closure glaucoma patients.

AIM: To document any correlation between previous acute angle-closure attack and the extent of synechial angle closure in chronic primary angle-closure glaucoma (PACG) patients. METHODS: Consecutive cases of chronic PACG with patent peripheral iridotomy had gonioscopy performed. The extents of synechial angle closure of those chronic PACG eyes with previous documented acute angle-closure attack were compared to those eyes without such a history. RESULTS: A total of 102 chronic PACG eyes of 102 patients were recruited. Twenty-seven eyes (26.5%) had a previous documented acute angle closure, while 75 eyes (73.5%) did not. The mean extent of synechial angle closure +/-1 SD was 307+/-68 degrees (range, 150-360 degrees) in those chronic PACG eyes with a history of previous acute angle closure, compared to 266+/-89 degrees (range, 90-360 degrees) in those chronic PACG eyes without such a history (P=0.03, Student's t-test). There were no statistically significant differences between the two groups in age, LogMAR visual acuity, intraocular pressure (IOP), number of glaucoma eye drops, vertical cup-to-disk ratio, mean deviation or pattern SD in Humphrey automated perimetry, and anterior chamber depth (P>0.05). CONCLUSION: Previous acute angle-closure attack correlated with more extensive synechial angle closure in chronic PACG patients in this study.

Effects of scan circle displacement in optical coherence tomography retinal nerve fibre layer thickness measurement: a RNFL modelling study.

OBJECTIVE: To study the effect of optical coherence tomography (OCT) scan circle displacement on retinal nerve fibre layer (RNFL) measurement errors using cubic spline models. METHODS: Forty-nine normal subjects were included in the analysis. In one randomly selected eye in each subject, RNFL thickness around the optic disc was measured by taking 16 circular scans of different sizes (scan radius ranged from 1 to 2.5 mm). The RNFL profile in each eye was constructed with a mathematical model using a smoothing spline approximation. Scan circle (diameter 3.4 mm) RNFL measurements (total average, superior, nasal, inferior, and temporal RNFL thicknesses) obtained from eight directions (superior, superonasal, nasal, inferonasal, inferior, inferotemporal, temporal, and superotemporal) displaced at different distances (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 mm) from the disc centre were then computed by a computer program and compared to the 'reference standard' where the scan circle is centred at the optic disc. RNFL measurement error was calculated as the absolute of (RNFL thickness(displaced) - RNFL thickness(reference standard)). RESULTS: The respective mean average, superior, nasal, inferior, and temporal RNFL measurement errors were 2.3+/-2.0, 4.9+/-4.5, 4.1+/-3.8, 6.2+/-7.6, and 3.8+/-3.5 microm upon 0.1 mm scan circle displacement, and 12.1+/-11.4, 27.8+/-18.4, 21.7+/-18.6, 34.8+/-22.9, and 15.2+/-10.7 microm upon 0.7 mm scan circle displacement. Significant differences of average and quadrant RNFL thicknesses were evident between centred and displaced scan circle measurements (all with P<0.001). RNFL measurement error increased in a monotonic fashion with increasing distance away from the disc and the change was direction-dependent. CONCLUSIONS: RNFL measurement error varies with the direction and distance of scan displacement. The superior and the inferior RNFL measurements are most vulnerable to scan displacement errors, whereas the average RNFL thickness is the least susceptible. Obtaining a well-centred scan is essential for reliable RNFL measurement in OCT.

Intravitreal bevacizumab (Avastin) for myopic choroidal neovascularisation: 1-year results of a prospective pilot study.

AIM: The aim of the study was to examine the 1-year results of intravitreal bevacizumab for myopic choroidal neovascularisation (CNV). METHODS: Twenty-nine eyes of 29 patients with myopic CNV were prospectively recruited to receive three initial monthly intravitreal bevacizumab injections. Three additional monthly injections were performed in eyes with persistent or recurrent CNV after 3 months. RESULTS: The mean spherical equivalent refractive error was -10.0 D. Sixteen eyes had previous photodynamic therapy (PDT) and 13 eyes had no prior PDT. All patients completed follow-up at 1 year. Following the initial three bevacizumab injections, 27 (93.1%) eyes had angiographic closure and two (6.9%) required further treatment. Two additional patients required re-treatment for CNV recurrence between 6 and 9 months. The mean baseline logarithm of the minimum angle of resolution (logMAR best-corrected visual acuity) was 0.62 (20/83), which improved to 0.38 (20/48) at 12 months (p<0.001). The mean visual improvement was 2.4 lines and 21 (72.4%) eyes had improvement of > or =2 lines. Optical coherence tomography showed significant reduction in central foveal thickness following treatment. Eyes without previous PDT were more likely to gain > or =2 lines after treatment than eyes that had previous PDT (p = 0.010). CONCLUSIONS: The 1-year outcomes confirmed the results of previous short-term studies that intravitreal bevacizumab is effective for myopic CNV, with a high proportion of patients sustaining visual gain after treatment.