Sector-Based Regression Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

This cross-sectional study aimed to investigate the sectoral variance of optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters across eyes with varying degrees of refractive error.

Methods

Healthy participants, including individuals with axial ametropia, enrolled in the Hong Kong FAMILY cohort were imaged using the Avanti/AngioVue OCT/OCTA system. The OCT and OCTA parameters obtained include peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), and macular ganglion cell complex thickness (GCCT). Sectoral measurements of NFLT, NFLP-CD, and GCCT were based on sectors and hemispheres.

Results

A total of 1339 eyes from 791 participants were stratified based on spherical equivalent refraction: high myopia (<-6 D), low myopia (-6 D to -1 D), emmetropia (-1 D to 1 D), and hyperopia (>1 D). Multivariable broken stick regression models, accounting for age, sex, and signal strength, showed that all NFLT sectors except temporally, the inferior GCCT hemisphere, and half of the NFLP-CD sectors were more affected by ametropia-related covariates than the corresponding global parameters. As expected, the false-positive rates in those sectors were elevated. Finally, sector-specific axial length (AL) and spherical equivalent (SE) adjustments helped reduce the elevated false-positive rates.

Conclusions

The effect of optical magnification is even more prominent among sectors than the global parameters. AL- and SE-based adjustments should be individualized to each sector to mitigate this magnification bias effectively.

Translational Relevance

Identifying sectoral differences among diagnostic parameters and adopting these sector-based adjustments into commercial OCT systems will hopefully reduce false-positive rates related to refractive error.

Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters.

Methods

OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis.

Results

A total of 1346 eyes from 792 participants were divided into 4 subgroups: high myopia (<−6D), low myopia (−6D to −1D), emmetropia (−1D to 1D), and hyperopia (>1D). After accounting for age, sex, and signal strength, multivariable regression showed strong dependence in most models for NFLT, GCCT, and NFLP-CD on axial eye length (AL), spherical equivalent (SE) refraction, and apparent optic disc diameter (DD). Optical analysis indicated that AL-related transverse optical magnification variations predominated over anatomic variations and were responsible for these trends. Compared to the emmetropic group, the false positive rates were significantly (Chi-square test P < 0.003) elevated in both myopia groups for NFLT, NFLP-CD, and GCCT. Regression-based adjustment of these diagnostic parameters with AL or SE significantly (McNemar test P < 0.03) reduced the elevated false positive rates.

Conclusions

Myopic eyes are biased to have lower NFLT, GCCT, and NFLP-CD measurements. AL- and SE-based adjustments were effective in mitigating this bias.

Translational Relevance

Adoption of these adjustments into commercial OCT systems may reduce false positive rates related to refractive error.

Effectiveness of Microcurrent Stimulation in Preserving Retinal Function of Blind Leading Retinal Degeneration and Optic Neuropathy: A Systematic Review

OBJECTIVES

To systematically identify and summarize the effectiveness and the parameters of electrical stimulation (ES) for the preservation of visual function in major retinal degeneration and optic neuropathy.

MATERIALS AND METHODS

A systematic review of clinical studies, using ES therapy in patients with blind leading retinal degenerations, including retinitis pigmentosa (RP), age-related macular degeneration (AMD), glaucoma, retinal vein occlusion (RVO), retinal artery occlusion (RAO), and optic neuropathy was conducted. PubMed, EMBASE, Cochrane Library, and Web of Science were searched for relevant interventional studies including randomized controlled trials (RCTs) and observational studies.

RESULTS

A total of 10 RCTs and 15 observational studies were included. Transcorneal ES (TcES), transpalpebral ES (TpES), transdermal ES (TdES), and repetitive transorbital alternating current stimulation (rtACS) were used for the treatment of the patients. ES using 20 Hz biphasic pulses with current strength at 150%-200% of individual electrical phosphene threshold (EPT) for RP patients showed improved retinal function detected by visual acuity (VA), visual field (VF), or electrical retinal graphs (ERG). rtACS on patients with optic neuropathy showed significant preservation of VA and VF. Clinical studies on AMD, RAO, and glaucoma indicated promising protective effects of ES on the visual function, though the amount of evidence is limited.

CONCLUSIONS

ES treatment has promising therapeutic effects on RP and optic neuropathy. More large-scale RCT studies should be conducted to elucidate the potential of ES, especially on AMD, RAO, and glaucoma. A comparison of the effects by different ES methods in the same disease populations is still lacking. Parameters of the electric current and sensitive detection method should be optimized for the evaluation of ES treatment effects in future studies.

Does the COVID-19 Pandemic Spell the End for the Direct Ophthalmoscope?

Despite advances in ophthalmic diagnostics, the direct ophthalmoscope remains a key clinical skill taught to medical students and is the tool of choice for retina examination among non-ophthalmic physicians. However, in recent years viable alternatives have become available. The coronavirus disease 2019 (COVID-19) pandemic has forced a major re-thinking in medical education worldwide. In this commentary, we examined the current merits and limitations of the direct ophthalmoscope in both the clinical sense and in the context of infection control. Furthermore, we compared the direct ophthalmoscope with alternatives, including commercially available portable non-mydriatic fundus cameras, that would allow a change in focus during ophthalmic teaching. We concluded that the latter will better prepare our medical students for the age of telemedicine and deep-learning systems. While the COVID-19 pandemic will not be the sole reason for the ‘death’ of the direct ophthalmoscope, the global situation will inevitably serve to expedite long overdue changes in our teaching of ophthalmic skills to non-ophthalmic physicians.

Macular Vessel Density Measured With Optical Coherence Tomography Angiography and Its Associations in a Large Population-Based Study

Purpose

We investigate macular perfusion and the systemic and ocular associations in a population-based setting.

Methods

In this cross-sectional study, 2018 adults residing in Hong Kong underwent detailed ophthalmic examinations after consenting to participate. Macular perfusion was measured with optical coherence tomography angiography (OCTA) using the split-spectrum amplitude decorrelation angiography algorithm. The parafoveal flow index and vessel area density were quantified using automated custom-built software.

Results

Of the 2018 participants, the OCTA measurements were available for 1940, and 1631 (84.1%) had good quality scans. The right eyes of these 1631 participants (43.1% men) were included for final analysis. Mean age was 49.8 years (range, 18-92 years). Mean global macular vessel density was 47.3% and 55.1% for the superficial and deep retinal layers, respectively. In multivariate analysis, lower superficial vessel density remained significantly associated with lower signal strength index (SSI; P < 0.001, standardized β = 0.607) and male sex (P < 0.001, β = 0.162), and borderline associated with older age (P = 0.09, β = -0.045) and longer axial length (AL; P = 0.09, β = -0.037), while lower deep layer vessel density was significantly associated with lower SSI (P < 0.001, standardized β = 0.667), longer AL (P < 0.001, β = -0.097), and higher creatinine (P < 0.001, β = -0.072).

Conclusions

This large population-based study provided normative OCTA data of macular vessel density and demonstrated that a lower superficial retinal vessel density was significantly associated with lower SSI and male sex, while a lower deep layer retinal vessel density was significantly associated with lower SSI, longer AL, and higher level of creatinine. These associations must be considered when interpreting clinical quantitative OCTA data.

Prospective study on a novel treatment for leaking cystic bleb: Efficacy and safety of collagen crosslinking

IMPORTANCE

Management of cystic bleb leak is difficult. It would be essential to look for a method to strengthen the original pathological conjunctiva and reverse bleb leak.

BACKGROUND

To evaluate the long-term efficacy and safety of collagen crosslinking in patients with leaking cystic bleb.

DESIGN

Prospective interventional case series at a university-based hospital.

PARTICIPANTS

Twelve eyes in 12 subjects with late-onset bleb leak from cystic bleb, without indications for prompt surgical interventions were included.

METHODS

The subjects underwent crosslinking with 0.1% riboflavin application to bleb surface, followed by ultraviolet irradiation for 30 minutes. The subjects were followed up at baseline and at 1 week, 1 month, 3 months, 6 months post-treatment and then every 6 months afterwards.

MAIN OUTCOME MEASURES

Interval from treatment to cessation of bleb leak, recurrence rate of bleb leak and side effects of treatment.

RESULTS

The mean follow-up after crosslinking was 29.33 ± 12.45 months. Bleb leak subsided in 11 (92%) of 12 patients after a single session of crosslinking, after 1 to 8 weeks (median 3 weeks). Time to leak cessation was significantly correlated with the number of prior glaucoma interventions (R = .71, P = .014). Bleb wall at 3 months was significantly thicker than at baseline (0.70 ± 0.67 vs 0.81 ± 0.62 mm, P = .008). None of the patients experienced any complications.

CONCLUSIONS AND RELEVANCE

Crosslinking achieves resolution of cystic bleb leak which lasts for at least 12 months, without the need of subsequent surgical interventions. Crosslinking is a simple, non-invasive treatment for bleb leak. It aims to restore the integrity of conjunctiva.

Optic neuritis as the initial clinical presentation of limbic encephalitis: a case report

BACKGROUND

Limbic encephalitis is characterized by rapid onset of working memory deficit, mood changes, and often seizures. The condition has a strong paraneoplastic association, but not all cases are invariably due to tumors.

CASE PRESENTATION

We present a case of limbic encephalitis in a Chinese patient who initially presented to our hospital with optic neuritis and no other neurological symptoms. The diagnosis was made radiologically, and cognitive and neurological symptoms did not occur until 5 months later. Extensive investigations for autoimmune, infective, and neoplastic causes were all negative. A working diagnosis of paraneoplastic neurological syndrome was made, and the patient is being managed with high-dose steroid therapy according to the Optic Neuritis Treatment Trial protocol during relapses, as well as with tumor surveillance.

CONCLUSIONS

This case highlights ocular symptoms as important clues for diagnosing neurological diseases, as well as autoimmune encephalitis as an important differential diagnosis in the management of "idiopathic" optic neuritis in the Chinese population.

Development and pilot-testing of patient decision aid for use among Chinese patients with primary open-angle glaucoma

Background

A patient decision aid (PDA) is a tool for shared decision making (SDM), which emphasises patient empowerment. It is useful in chronic diseases and when there are multiple, no best single treatment option. Although SDM is prevalent in Western countries, its use is limited in Chinese societies, where the adoption of a paternalistic approach is strong. Here, we report the development, acceptance and pilot test results of a PDA targeted at Chinese patients with primary open-angle glaucoma (POAG).

Methods

We developed a PDA designed for use in Chinese patients with POAG. Recruited subjects were given our PDA. Baseline evaluation included decision conflict scale (DCS), validated glaucoma adherence questionnaires and glaucoma knowledge questionnaire. Subjects were briefed through the PDA and instructed to read it that day. Three to four weeks later, follow-up questionnaire as described above were conducted with the addition of acceptance questionnaires.

Results

Data from 65 subjects were available. The PDA was well received among subjects. DCS improved from 48.9±20.4 at baseline to 34.3±20.3 during follow-up, with P<0.01. Validated medication adherence questionnaires and knowledge showed improvement from baseline, which was statistically significant.

Conclusions

The use of PDA among Chinese subjects with POAG demonstrated positive reception and acceptance. Evaluation of its initial effects shows improvement in DCS, medication adherence and glaucoma knowledge. The implementation of SDM and PDA among Chinese subjects with POAG is encouraged. Future studies with randomised design and later evaluation time points can further reveal the impacts of PDA among Chinese subjects with POAG.

A cross-sectional comparative study on chronic ocular manifestations of Stevens-Johnson syndrome and toxic epidermal necrolysis in Chinese eyes: a 15-year case series

PURPOSE

To compare the chronic ocular manifestations in Stevens-Johnson syndrome and toxic epidermal necrolysis patients from a 15-year cohort.

METHODS

All SJS and TEN patients admitted to our burn intensive care unit between 1999 and 2014 were invited for assessment. Slit-lamp examination was performed, and ocular condition was graded according to the Sotozono scoring System, which depended on the extent of cornea, conjunctiva and lid involvement. Tear osmolarity was also measured.

RESULTS

A total of 18 SJS and 4 TEN cases with an average of 92 and 135 months from disease onset were included. The average age of onset was 46.4 ± 16.6 in SJS and 43.5 ± 19.3 in TEN patients. The LogMAR visual acuity was 0.209 ± 0.591 in SJS and 0.489 ± 0.688 in TEN patients (p = 0.048). The average total Sotozono score was 3.75 ± 7.32 in SJS and 6.88 ± 9.49 in TEN (p = 0.358). Neither the age of onset (p = 0.787), length of follow-up (p = 0.256) nor disease type (SJS vs TEN, p = 0.188) predicted the Sotozono score. There was a statistically significant correlation between Sotozono score and LogMAR VA (r _s = 0.437, p = 0.003).

CONCLUSION

The average total Sotozono score was higher in the TEN group than in the SJS group, but the difference was not statistically significant. Nevertheless, the score correlated with the visual acuity which was statistically worse in the TEN group.

Comparison of the acute ocular manifestations of Stevens-Johnson syndrome and toxic epidermal necrolysis in Chinese eyes: a 15-year retrospective study

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but life-threatening conditions that initially affect the skin and mucous membranes. The aim of this study was to compare the acute ocular manifestations between SJS and TEN.

METHODS

The initial presenting ophthalmic records of patients with either SJS (<30% body surface area involvement) or TEN (> = 30% involvement), who were treated at one tertiary burn center in Hong Kong between 1999 and 2014, were retrospectively analyzed and compared.

RESULTS

A total of 20 SJS and 12 TEN cases were included. All were drug-induced. The patient demographics and treatment received were comparable. Overall, 40% of SJS and 75% of TEN patients had acute ocular surface inflammation. When comparing the two groups, there was a significant difference in the number of cases with mild involvement (5% in SJS, 42% in TEN, p = 0.01), while no statistically significant differences were found (p > 0.05) comparing between the moderate (15% in SJS, 0% in TEN) and severe groups (20% in SJS, 33% in TEN).

CONCLUSIONS

Ocular surface inflammation was common during the acute phase in both SJS and TEN. TEN had a significantly higher number of cases with mild ocular involvement when compared with SJS, but no significant difference between the number of moderate and severe cases between the two groups.

Efficacy and Safety of Trabectome Surgery in Chinese Open-Angle Glaucoma

To investigate the clinical outcome of the Trabectome in Chinese open-angle glaucoma (OAG). This prospective case series recruited pseudophakic glaucoma subjects with open-angle configuration. Trabeculectomy ab interno was performed using the Trabectome to 120° of the trabecular meshwork. Intraocular pressure (IOP) and medications were recorded preoperatively and every 3 months postoperatively. Visual acuity was measured preoperatively and at 1 and 6 months postoperatively. One-way ANOVA with Tukey Multiple Comparison Test were used to measure the pre and postoperative parameters. In 19 eyes of 19 Chinese subjects, 26.3% were uveitic, 68.4% were primary open-angle glaucoma, and 5.3% had a history of chronic angle-closure glaucoma with open-angles after cataract extraction. The subjects' mean age was 67.5 ± 14.4 years, with 4 females and 15 males. Two patients required secondary filtration procedure. At 6 months, the IOP reduced by 34.8% (24.4 ± 4.4 mm Hg to 15.9 ± 5.1 mm Hg, P < 0.0001). The number of types of antiglaucoma medications was reduced by 28.2% (3.9 ± 0.8-2.8 ± 1.6, P < 0.0001). The visual acuity was static at 1 and 6 months postoperatively (P = 0.4). There were no intraoperative complications. 26.3% of subjects had a transient IOP spike > 21 mm Hg, 1 had hyphema requiring washout, and 1 had reactivation of herpetic keratitis. The success rate at 6 months was 89.5%. Trabectome achieved a modest reduction in IOP and medications in the majority of pseudophakic Chinese OAG eyes.

A review of selective laser trabeculoplasty in the Hong Kong Chinese population

INTRODUCTION

Selective laser trabeculoplasty was first introduced to Hong Kong in 2004 for intra-ocular pressure lowering in the treatment of primary glaucoma. Since then, it has gained popularity as an alternative to anti-glaucoma medications and as a bridging therapy prior to more invasive glaucoma surgeries because of the high safety profile of the laser.

METHODS

An Ovid search was performed using "selective laser trabeculoplasty" as the key word, which identified 190 unique articles; 24 reviews and/or meta-analyses were excluded. All remaining abstracts of original articles were in English. This review particularly focuses on the local population by summarising the findings from peer-reviewed publications that involved a Hong Kong Chinese population.

RESULTS AND CONCLUSION

This review addresses some of the clinically relevant questions relating to selective laser trabeculoplasty including laser application, optimal energy, efficacies and success rates among different glaucoma subtypes, predictors of success, adverse effects, and intra-ocular pressure fluctuation after selective laser trabeculoplasty.

Age-Related True Exfoliation of the Lens Capsule: Phacoemulsification Surgery Results

Historically associated with glassblowers, true exfoliation of the crystalline lens involves a splitting or delamination of the capsule. We reviewed the phacoemulsification records of a single surgeon for patients with true exfoliation of the lens capsule. The incidence in our series was 2.2% (6 in 278 cases). The average age was 85.0 years. All patients had successful phacoemulsification outcomes, which may have been due to accurate recognition of the condition and appropriate surgical planning. Our findings support the notion that true exfoliation may be more often associated with advanced age rather than infrared radiation.

Two-Year Clinical Results After Selective Laser Trabeculoplasty for Normal Tension Glaucoma

This article aims to investigate the clinical results at 2 years after selective laser trabeculoplasty (SLT) for normal tension glaucoma (NTG). This prospective cohort study recruited NTG patients taking antiglaucoma medication. Subjects were excluded if they had previous glaucoma surgery/laser or corneal pathologies. All subjects underwent a 1-month washout. A single session of SLT was performed to 360° of the trabecular meshwork. Medication was resumed at 1 month to achieve a targeted 30% intraocular pressure (IOP) reduction from the post-washout/pre-SLT IOP. IOP was measured every 3 months and medication use was recorded at 3, 6, 12, and 24 months. Subjects with a secondary SLT or cataract extraction were excluded from IOP and medication analyses. At 24 months, 34 of the initial 45 right eyes were eligible for analyses. There were significant IOP reductions at all time intervals (except at 1 week) following SLT when compared to the prestudy (without medication) or pre-SLT (post-washout) IOP (P < 0.0001). Medications were likewise significantly reduced at all time intervals following SLT (P < 0.0001). At 24 months, the IOP was 11.5% lower than the prestudy IOP, 22.0% lower than the pre-SLT IOP, and medication use was reduced by 41.1% (P < 0.0001). Six out of 45 eyes (13.3%) required a secondary SLT. Absolute success (IOP reduction >20% from pre-SLT, without medication) was achieved in 11.1% (5/45). Reductions in IOP and medication use were evident at 2 years following SLT for the treatment of NTG whereas 11% remained medication free.

TRIAL REGISTRATIONS

The Clinical Trials Register of the University of Hong Kong HKCTR1847. The European Clinical Trials Database 2014-003305-15 (August 11, 2014).

The Correlation of Retinal Nerve Fiber Layer Thickness With Blood Pressure in a Chinese Hypertensive Population

To investigate the association between retinal nerve fiber layer (RNFL) thickness and blood pressure (BP) in subjects with systemic hypertension. Subjects with systemic hypertension on anti-hypertensive medications were screened by fundus photography and referred for glaucoma work-up if there was enlarged vertical cup-to-disc (VCDR) ratio ≥0.6, VCDR asymmetry ≥0.2, or optic disc hemorrhage. Workup included a complete ophthalmological examination, Humphrey visual field test, and RNFL thickness measurement by optical coherence tomography. The intraocular pressure (IOP) and RNFL thicknesses (global and quadrant) were averaged from both eyes and the means were correlated with: the systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) using Pearson correlation. Among 4000 screened hypertensive subjects, 133 were referred for glaucoma workup and 110 completed the workup. Of the 4000 screened subjects, 1.3% had glaucoma (0.9% had normal tension glaucoma [NTG], 0.2% had primary open angle glaucoma, and 0.2% had primary angle closure glaucoma), whereas 0.3% were NTG suspects. The SBP was negatively correlated with the mean superior RNFL thickness (P = 0.01). The DBP was negatively correlated with the mean global (P = 0.03), superior (P = 0.02), and nasal (P = 0.003) RNFL thickness. The MAP was negatively correlated with the mean global (P = 0.01), superior (P = 0.002), and nasal (P = 0.004) RNFL thickness while positively correlated with the mean IOP (P = 0.02). In medically treated hypertensive subjects, glaucoma was present in 1.3%, with NTG being most prevalent. MAP control may help with IOP lowering and RNFL preservation, although future prospective studies will be needed.

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

The 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 μm, n = 73), followed by the emmetropic group (102.5 ± 9.2 μm, 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.

The association between macular thickness and peripapillary retinal nerve fiber layer thickness in Chinese children

To investigate the association between macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness in Chinese children. This cross-sectional study recruited consecutive cases of healthy pediatric subjects aged 4 to 18 from Caritas Medical Centre in Hong Kong Special Administrative Region, China, from 2013 to 2014. Subjects with only eye, ocular tumors, congenital glaucoma, congenital cataract, congenital nystagmus, microphthalmos, optic nerve or retinal disease, active ocular infections, corneal scars, and severe visual impairment of any cause were excluded. Peripapillary RNFL thickness and macular thickness at 1-mm-diameter fovea center (C1), 3-mm-diameter temporal quadrant (T3), and 3-mm-diameter nasal quadrant (N3) were measured with optical coherence tomography. Best-corrected visual acuity, axial length, and cycloplegic refraction were also recorded. Spearman correlation was used to analyze the association between T3, C1, and N3 with each of the following: average and quadrant RNFL thickness, axial length, and spherical equivalent. In 179 subjects, the mean age was 7.9 ± 3.6 years. There were 90 male and 89 female subjects, all of Chinese ethnicity. The mean spherical equivalent was -0.1 ± 3.1 D and mean axial length was 22.9 ± 1.4 mm. There were significant and positive correlations of the average (T3: r = 0.20, P = 0.04; N3: r = 0.2, P = 0.005), superior (T3: r = 0.20, P = 0.03; N3: r = 0.2, P = 0.03), and inferior (T3: r = 0.20, P = 0.02; N3: r = 0.2, P = 0.01) peripapillary RNFL thicknesses with the T3 and N3 macular thicknesses but not C1. The nasal peripapillary RNFL thickness was also positively correlated with T3 (r = 0.20, P = 0.01). There were no significant associations between the macular thickness (T3, C1, N3) with neither the spherical equivalent (P > 0.2) nor the axial length (P > 0.3). The macular thickness was positive correlated with the peripapillary RNFL thickness in a population of healthy Chinese children.

Factors correlating with failure to control intraocular pressure in primary angle-closure glaucoma eyes with coexisting cataract treated by phacoemulsification or combined phacotrabeculectomy

PURPOSE

To identify clinical factors correlating with failure to control intraocular pressure (IOP) in primary angle-closure glaucoma (PACG) eyes with cataract after phacoemulsification or phacotrabeculectomy.

DESIGN

Retrospective analysis of two prospective randomized controlled clinical trials.

METHODS

Primary angle-closure glaucoma eyes with cataract received phacoemulsification or phacotrabeculectomy. Failure was defined as having IOP of 21mm Hg or greater, or requiring glaucoma drugs to maintain an IOP of less than 21 mm Hg, or having had additional IOP-lowering surgery. Factors correlating with failure at 24 months after surgery were identified using logistic regression model.

RESULTS

One hundred twenty-three PACG eyes with cataract and receiving phacoemulsification (n = 62) and phacotrabeculectomy (n = 61) were analyzed. With univariate analysis, factors associated with failure included a higher preoperative IOP, a higher preoperative requirement for glaucoma drugs, absence of plateau iris configuration, and phacoemulsification alone. With multivariate analysis, factors associated with failure included a higher preoperative IOP [odds ratio (OR), 1.732 per increase in IOP of 5 mm Hg], a higher preoperative requirement for glaucoma drugs (OR, 1.913), and performance of phacoemulsification alone (OR, 10.24).

CONCLUSIONS

In PACG eyes with cataract, higher preoperative IOP and increased requirement for glaucoma drugs correlate with failure to control IOP after phacoemulsification or phacotrabeculectomy. Phacotrabeculectomy is more likely than phacoemulsification to achieve IOP control.

Twenty-four-hour intraocular pressure related changes following adjuvant selective laser trabeculoplasty for normal tension glaucoma

To investigate intraocular pressure (IOP) related patterns before and after selective laser trabeculoplasty (SLT) for normal tension glaucoma (NTG).In this prospective cohort study, 18 NTG patients underwent SLT. Success was defined as IOP reduction ≥ 20% by Goldmann applanation tonometry. 24-hour IOP-related pattern recording with a contact lens sensor (CLS) (SENSIMED Triggerfish, Sensimed, Switzerland) was done before (baseline) and 1 month after SLT. A cosine function was fitted to the mean CLS patterns for each individual in the SLT success and non-success groups and the amplitude before and after SLT was calculated. Diurnal, nocturnal, and 24-hour CLS pattern local variability was determined for pre- and post-SLT sessions. Cosine amplitude and variability were compared before and after SLT by group using paired t-tests, with α = 0.05. Patients (11 women, 7 men) had a mean age of 65.1 ± 13.7 years. Mean IOP was 15.3 ± 2.2 mm Hg at baseline and was reduced by 17.0% to 12.7 ± 1.8 mm Hg 1 month after SLT (P = 0.001). SLT was successful in 8 patients (44%). The amplitude of the fitted cosine was reduced by 24.6% in the success group, but displayed an amplitude increase of 19.2% post-SLT in the non-success group. Higher diurnal local variability of the CLS pattern was observed after SLT in non-success subjects (P = 0.002), while nocturnal variability showed no significant change. The increase in diurnal variability in the non-success group led to an increase in 24-hour variability in this group (P = 0.001). No change in local variability (diurnal, nocturnal, and 24-hour) was seen in the success group. The IOP-related pattern cosinor amplitude was reduced in NTG patients with a successful SLT treatment whereas the non-success group exhibited an increase of cosine amplitude. Higher diurnal and 24-hour CLS pattern variability was observed in non-success patients 1 month post-SLT.

Predictors of success in selective laser trabeculoplasty for normal tension glaucoma

To determine the predictors of success for selective laser trabeculoplasty (SLT) in normal tension glaucoma (NTG). This prospective cohort study recruited subjects with unilateral or bilateral NTG on medication. All subjects received a single session of 360° SLT treatment. SLT success was defined as IOP reduction≥20% at 1-month. The following covariates were analyzed via univariate and multivariate analyses: age; sex; lens status; presenting, pre-SLT, and post-SLT IOP's; number and type of medications; SLT shots and energy; and pre-SLT investigations. In 60 eyes of 32 subjects with NTG, there were 30 right eyes and 28 left eyes. The success rate of SLT was 61.7%. Using 3 types of anti-glaucoma medications (coefficient=-2.2, OR=0.1, P=0.02) and a thicker retinal nerve fiber layer thickness (coefficient=-0.04, OR=0.96, P=0.04) were associated with failure (univariate analysis). In multivariate analysis, a higher pre-SLT IOP (coefficient=1.1, OR=3.1, P=0.05) and a lower 1-week IOP (coefficient=-0.8, OR=0.5, P=0.04) were associated with success. SLT was successful in over 60% of treated NTG patients. A higher pre-SLT IOP and a greater IOP reduction at 1-week post-SLT were predictors of a successful outcome.

The association between clinical parameters and glaucoma-specific quality of life in Chinese primary open-angle glaucoma patients

OBJECTIVE. To investigate the association between clinical measurements and glaucoma-specific quality of life in Chinese glaucoma patients. DESIGN. Cross-sectional study. SETTING. An academic hospital in Hong Kong. PATIENTS. A Chinese translation of the Glaucoma Quality of Life-15 questionnaire was completed by 51 consecutive patients with bilateral primary open-angle glaucoma. The binocular means of several clinical measurements were correlated with Glaucoma Quality of Life-15 findings using Pearson's correlation coefficient and linear regression. The measurements were the visual field index and pattern standard deviation from the Humphrey Field Analyzer, Snellen best-corrected visual acuity, presenting intra-ocular pressure, current intra-ocular pressure, average retinal nerve fibre layer thickness via optical coherence tomography, and the number of topical anti-glaucoma medications being used. RESULTS. In these patients, there was a significant correlation and linear relationship between a poorer Glaucoma Quality of Life-15 score and a lower visual field index (r=0.3, r(2)=0.1, P=0.01) and visual acuity (r=0.3, r(2)=0.1, P=0.03). A thinner retinal nerve fibre layer also correlated with a poorer Glaucoma Quality of Life-15 score, but did not attain statistical significance (r=0.3, P=0.07). There were no statistically significant correlations for the other clinical parameters with the Glaucoma Quality of Life-15 scores (all P values being >0.7). The three most problematic activities affecting quality of life were "adjusting to bright lights", "going from a light to a dark room or vice versa", and "seeing at night". CONCLUSION. For Chinese primary open-angle glaucoma patients, binocular visual field index and visual acuity correlated linearly with glaucoma-specific quality of life, and activities involving dark adaptation were the most problematic.

Prospective study on retinal nerve fibre layer changes after an acute episode of phacomorphic angle closure

To investigate the retinal nerve fibre layer (RNFL) changes after an acute attack of phacomorphic angle closure. This prospective study involved ten cases of phacomorphic angle closure that underwent cataract extraction and intraocular lens insertion after intraocular pressure lowering. Apart from visual acuity and intraocular pressure (IOP), RNFL thickness and vertical cup disc ratio (VCDR) were measured by optical coherence tomography (OCT) at 3–9 months post attack. Humphrey visual field assessment was performed at 9 months post attack. All cases had mean phacomorphic duration of <5 days. Postoperatively, best correct Snellen visual acuity was 0.4 ± 0.2 and IOP at 9 months was 11.0 ± 3.1 mmHg. There was no difference in VCDR and RNFL between the attack and contralateral eye at 3 months post attack (both p = 0.4). At 9 months post attack, there was significant thinning in the average (p = 0.01), superior (p = 0.01), and inferior (p = 0.006) RNFL. There was no significant difference in the pattern standard deviation (PSD) between the two eyes on the Humphrey visual field nor was there any correlation between PSD severity and RNFL thinning (all p > 0.2. Patients with <5 days duration of phacomorphic angle closure are likely to have reasonable postoperative vision. An acute episode of phacomorphic angle closure can trigger an accelerated RNFL thinning despite normal IOP and open angles, most noticeable in the superior and inferior quadrants, occurring between 3 and 9 months post attack. Glaucomatous optic neuropathy in the attack eye was evident by OCT but not by visual field assessment at the same time interval.

Medication-induced acute angle closure attack

OBJECTIVE

To review acute angle closure attacks induced by local and systemic medications.

DATA SOURCES

PubMed literature searches up to August 2011.

STUDY SELECTION

The following key words were used for the search: "drug", "iatrogenic", "acute angle closure glaucoma".

DATA EXTRACTION

A total of 86 articles were retrieved using the key words. Only those concerning acute angle closure attack triggered by local or systemic drug administration were included. For articles on the same or related topics, those published at later or more recent dates were selected. As a result, 44 articles were included and formed the basis of this review.

DATA SYNTHESIS

An acute attack of angle closure can be triggered by dilatation of the pupil, by anatomical changes in the ciliary body and iris, or by movement of the iris-lens diaphragm. Local and systemic medications that cause these changes have the potential to precipitate an attack of acute angle closure. The risk is higher in subjects who are predisposed to the development of angle closure. Many pharmaceutical agents including ophthalmic eyedrops and systemic drugs prescribed by general practitioners and various specialists (in psychiatry, otorhinolaryngology, ophthalmology, medicine, and anaesthesia) can precipitate an acute angle closure attack. The medications include: anti-histamines, anti-epileptics, antiparkinsonian agents, antispasmolytic drugs, mydriatic agents, sympathetic agents, and botulinum toxin.

CONCLUSION

Since acute angle closure attack is a potentially blinding eye disease, it is extremely important to be vigilant and aware of ophthalmic and systemic medications that can lead to such attacks in predisposed subjects and to diagnose the condition when it occurs.

Retrospective analysis of the risk factors for developing phacomorphic glaucoma

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.

A New Acute Attack of Angle Closure Glaucoma Animal Model with Healon 5

Acute angle closure glaucoma (AACG) is an ocular emergency and sight -threatening disease in which the intraocular ocular pressure (IOP) rises suddenly due to blockage of aqueous humor outflow. It can cause permanent loss in visual acuity and visual field. In animal study, the well-established model to study AACG is by fluid infusion and by adjusting the bottle level, a high IOP can be induced in a few seconds. However, there is no blockage of aqueous outflow and the pressure rise is unrealistically fast. To mimic human AACG, we suggest to use Healon 5, an ophthalmic viscosurgical device, which is injected intracamerally to block the aqueous outflow. The IOP is allowed to build up naturally. We found that, with this technique, the IOP elevated at a rate of 0.57 mmHg/min before it hit 40 mmHg, which is considered as AACG in human. The maximum IOP registered was above 70 mmHg. Thinning of retinal nerve fiber layer (RNFL) and neural cells lost were seen. Visual function evaluated by ERG showed reduction in a-wave, b-wave, photopic negative response (PhNR) and oscillatory potentials (OPs) activities. In conclusion, Healon 5 is effective in inducing acute transient rise in IOP which mimics human AACG.

Phacoemulsification vs phacotrabeculectomy in chronic angle-closure glaucoma with cataract: complications [corrected]

OBJECTIVE

To compare the complications of phacoemulsification alone vs combined phacotrabeculectomy in chronic angle-closure glaucoma (CACG) with coexisting cataract.

METHODS

Patients with CACG with coexisting cataract recruited into 2 randomized controlled trials comparing phacoemulsification alone vs combined phacotrabeculectomy were pooled for analysis. The first trial recruited patients with medically controlled intraocular pressure, while the second trial recruited patients with medically uncontrolled intraocular pressure. The 2 trials had otherwise identical study designs. All patients were reviewed every 3 months for 2 years after surgery. The main outcome measure was the surgical complications of phacoemulsification alone vs combined phacotrabeculectomy in CACG eyes with cataract.

RESULTS

One hundred twenty-three CACG eyes with cataract from 123 patients were included. Sixty-two CACG eyes were randomized to receive phacoemulsification alone, and 61 eyes had combined phacotrabeculectomy. In the phacoemulsification group, 5 of the 62 CACG eyes (8.1%) had a total of 5 surgical complications. In the combined phacotrabeculectomy group, 16 of the 61 CACG eyes (26.2%) had a total of 19 surgical complications. The difference in the proportion of eyes with 1 or more surgical complications between the 2 treatment groups was statistically significant (P = .007, Pearson chi(2) test). There was no statistically significant difference in final visual acuity or glaucomatous progression during the 24-month follow-up.

CONCLUSIONS

Combined phacotrabeculectomy resulted in significantly more surgical complications than phacoemulsification alone in CACG eyes with coexisting cataract. There was no difference in visual acuity or disease progression between the 2 treatment groups.

Orbital myiasis complicating squamous cell carcinoma of eyelid

Myiasis is infestation of the body by fly maggots. Immobile patients with skin wounds in exposed areas are at high risk of developing myiasis. We report a case of orbital myiasis from the species Chrysomya bezziana complicating squamous cell carcinoma of the eyelid. Magnetic resonance imaging of the orbit is useful for delineating the extent of the infestation and identifying residual maggots. In extensive orbital myiasis, exenteration is needed to prevent intracranial extension of tissue destruction.

Enophthalmos caused by an orbital venous malformation

Orbital vascular malformations usually present with proptosis. We report a case where a patient with an orbital venous malformation presented with enophthalmos. Since many underlying orbital pathologies, including orbital metastases, can cause enophthalmos, it is important to investigate patients properly. Computed tomographic imaging of the orbit remains the most useful tool in the management of patients with enophthalmos.

Incisional surgery for angle closure glaucoma

Angle closure glaucoma remains a major challenge for ophthalmologists. The three main challenges in the treatment of angle closure glaucoma are, firstly, to achieve rapid reduction of intraocular pressure in acute angle closure glaucoma, secondly, to prevent progression to chronic angle closure glaucoma, and thirdly, to manage established chronic angle closure glaucoma. Incisional surgery for angle closure glaucoma is typically required when laser surgery and/or medical therapy fail to control the intraocular pressure or control progressive synechial closure. The role for surgical iridectomy and emergency trabeculectomy in the modern management of acute angle closure glaucoma is diminishing. Trabeculectomy, goniosynechialysis, cyclodestructive procedures, and glaucoma implant are effective surgical options for chronic angle closure glaucoma, but none of them have been shown to be more effective than the others with proper comparative clinical trials. Trabeculectomy and goniosynechialysis are often combined with cataract extraction, which appears to offer additional pressure-control benefits to patients with chronic angle closure glaucoma.

Toxic endothelial cell destruction syndrome after intraocular lens repositioning with intracameral epinephrine

A 66-year-old Chinese man developed corneal endothelial decompensation after intraocular lens (IOL) repositioning using intracameral epinephrine was performed. The presentation was compatible with toxic endothelial cell destruction syndrome, which is caused by prolonged, direct exposure of the corneal endothelium to relatively high concentrations of intracameral epinephrine. Despite its effective and immediate mydriatic effect, intracameral epinephrine is not recommended for intraoperative mydriasis in procedures such as IOL repositioning or secondary IOL implantation in which minimal irrigating solution is used.

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.

Pseudomonas aeruginosa choroidal abscess in a patient with bronchiectasis

PURPOSE

To report a case of Pseudomonas aeruginosa endophthalmitis with choroidal abscess formation in a patient with bronchiectasis.

METHODS

Case report.

RESULTS

A 75-year-old gentleman with bronchiectasis and P. aeruginosa pneumonia developed painless loss of right eye vision. The patient had previously undergone bronchoscopy to exclude pulmonary neoplasm. Slit-lamp examination revealed intense anterior chamber inflammation with hypopyon and B-scan ophthalmic ultrasound showed a choroidal mass consistent with choroidal abscess. Systemic and topical antibiotics did not prevent further progression of the infection. Patient declined pars plana vitrectomy and opted for enucleation. Polymerase-chain-reaction-based restriction fragment-length polymorphism (PCR-RFLP) of the enucleated eye confirmed P. aeruginosa to be the causative organism.

CONCLUSION

P. aeruginosa cannot be completely eradicated by systemic antibiotics, and bronchial colonization of P. aeruginosa can remain a potential source for metastatic infection. P. aeruginosa choroidal abscess, previously reported only in patients with cystic fibrosis, can also occur in bronchiectasis. Physicians should therefore have a high index of suspicion of endogenous endophthalmitis and treat aggressively, especially in patients with subretinal invasion and abscess formation.

Current approaches to the management of acute primary angle closure

PURPOSE OF REVIEW

Recent advances in the management of acute primary angle closure include argon laser peripheral iridoplasty, immediate anterior chamber paracentesis, and cataract or lens extraction by phacoemulsification. This review summarizes current thoughts on the role of these treatment modalities.

RECENT FINDINGS

Argon laser peripheral iridoplasty has been shown to be superior to treatments using combined topical and systemic medications in controlling intraocular pressure in acute primary angle closure. Immediate paracentesis has been shown to be very effective for aborting the condition. This is a good alternative for suitable cases and especially in settings in which laser equipment is not readily available. Cataract or lens extraction by phacoemulsification appears to be promising in preventing progression to chronic angle closure glaucoma after acute primary angle closure.

SUMMARY

Surgical trials are underway to examine the role of cataract/lens extraction in post-acute primary angle closure. This technique has the potential to prevent recurrence of the condition and progression to chronic angle closure glaucoma. With existing and upcoming new data on managing acute primary angle closure, it is hopeful that a more optimal treatment algorithm will be established soon.

Corneal injury by wild taro

We report a case of crystalline keratopathy caused by Alocasia macrorrhiza. The diagnosis was made based on the observation of needle-like crystals in the corneal stroma following injury to that eye. The condition resolved in 3 months with the disappearance of the crystals confirmed by follow-up confocal microscopy.

Effect of a previous acute angle closure attack on the corneal endothelial cell density in chronic angle closure glaucoma patients

PURPOSE

To document the effect of a previous acute angle closure attack on the corneal endothelial cell density in chronic angle closure glaucoma (CACG) patients.

METHODS

Consecutive cases of CACG with patent peripheral iridotomy had their central corneal endothelial cell density measured by specular microscopy. The corneal endothelial cell density of those CACG eyes with a previous documented acute angle closure attack were compared with those eyes without such a history, to determine the effect of a previous acute angle closure attack on corneal endothelial cell density.

RESULTS

From July 2003 to July 2005, a total of 52 CACG eyes of 52 patients fulfilling the study criteria were recruited. Thirteen eyes (25%) had a previous documented acute angle closure attack, whereas 39 eyes (75%) did not. The mean central corneal endothelial cell density +/-1 standard deviation was 2271.7+/-312.9 (range, 1556 to 2661) cells/mm in those CACG eyes with previous acute angle closure, and 2570.0+/-429.9 (range, 1669 to 3861) cells/mm in those CACG eyes without previous acute angle closure (P < 0.05, Student t test). A previous acute angle closure attack in a CACG eye correlates with a 11.6% reduction in corneal endothelial cell density, compared with a CACG eye without such a history. There were no statistically significant differences between the 2 groups in age, LogMAR visual acuity, intraocular pressure, number of glaucoma eye drops, vertical cup-to-disk ratio, mean deviation or pattern standard deviation in Humphrey automated perimetry (P > 0.05).

CONCLUSIONS

A previous acute angle closure attack correlates with a significantly reduced corneal endothelial cell density in CACG patients.