Minimally Invasive Glaucoma Surgery in Primary Angle-Closure Glaucoma.

Primary angle-closure glaucoma (PACG) is responsible for half of the glaucoma-related blindness worldwide. Cataract surgery with or without trabeculectomy has been considered to be the first-line treatment in eyes with medically uncontrolled PACG. While minimally invasive glaucoma surgery has become an important surgical approach for primary open-angle glaucoma, its indications and benefits in PACG are less clear. This review summarizes the efficacy and safety profile of minimally invasive glaucoma surgery in PACG to unfold new insights into the surgical management of PACG.

Latest Developments in Normal-Pressure Glaucoma: Diagnosis, Epidemiology, Genetics, Etiology, Causes and Mechanisms to Management.

Normal-pressure glaucoma (NPG) is part of the spectrum of the open-angle glaucomas and morphologically characterized, as any glaucoma, by a loss of neuroretinal rim parallel to an enlargement and deepening of the optic cup, and development or enlargement of parapapillary beta zone. These morphological characteristics, in addition to the therapeutic benefit of lowering the intraocular pressure (IOP), make NPG differ from vascular-induced optic neuropathy. Based on the anatomy of the optic nerve as a cerebral fascicle, the physiological counter-pressure against the IOP is the orbital cerebrospinal fluid pressure (CSFP), with both pressures forming the trans-lamina cribrosa pressure difference (TLCPD). In contrast to the IOP, the TLCPD is the true pressure exerting force on the optic nerve fibers when passing through the lamina cribrosa. As a theoretical notion, an abnormally high TLCPD due to a low CSFP, in association with a low arterial blood pressure, could therefore be involved in the pathogenesis of NPG. It fits with the finding that the reduction of the IOP (and thus indirectly of the TLCPD) is (the only proven) procedure for NPG therapy. This review additionally highlights the genetic background, diagnostic methods, and therapeutic modalities of NPG.

Preliminary results of CO2 laser-assisted sclerectomy surgery (CLASS) in the treatment of advanced glaucoma in a Chinese population.

To evaluate the efficacy and safety of CO2 laser-assisted sclerectomy surgery (CLASS) in Chinese patients with advanced glaucoma.Patients with advanced glaucoma who were candidates for glaucoma filtration surgery were included. The intraocular pressure (IOP) and number of antiglaucoma medications were documented before surgery and at all postoperative clinic visits. All intra- and postoperative complications were documented. The primary outcome measures were the changes in IOP and medication use before and after the procedure as well as complications from the procedure. The secondary outcome measure included the CLASS success rate.Twenty patients (23 eyes) underwent CLASS between November 2014 and September 2015. Nineteen eyes had primary open-angle glaucoma, 2 eyes had primary angle-closure glaucoma, and 2 eyes had uveitic glaucoma. One patient was lost to follow-up. The mean age of subjects was 68.1 ±â€Š11.9 years. IOP was significantly reduced at 1 day and 1 week after CLASS. At 6 months, the IOP and number of medications were significantly reduced by 19.0% and 38.2%, respectively (both P < 0.0001). One patient had intraoperative trabeculo-Descemet membrane perforation. Two patients required laser goniopuncture and 2 required needling between 3 and 6 months postoperatively. The overall success rate was 81.8% at 6 months.CLASS achieved a modest IOP reduction in the early postoperative period and was overall a safe procedure for advanced glaucoma.

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

PURPOSE: To determine the incidence and risk factors of retinopathy of prematurity (ROP) in very low birth weight (VLBW) preterm Chinese infants. DESIGN: Retrospective review. METHODS: Medical 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. RESULTS: Of 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). CONCLUSIONS: In VLBW preterm Chinese infants, lower GA, lighter BW, and intraventricular hemorrhage were significant risk factors for ROP, whereas preeclampsia and eclampsia were protective.

Accuracy of Intraocular Lens Power Calculation Formulas for Highly Myopic Eyes.

Purpose. To evaluate and compare the accuracy of different intraocular lens (IOL) power calculation formulas for eyes with an axial length (AL) greater than 26.00 mm. Methods. This study reviewed 407 eyes of 219 patients with AL longer than 26.0 mm. The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Results. One hundred seventy-one eyes were enrolled. The Barrett Universal II formula had the lowest mean absolute error (MAE) and SRK/T and Haigis had similar MAE, and the statistical highest MAE were seen with the Holladay and Hoffer Q formulas. The interquartile range of the Barrett Universal II formula was also the lowest among all the formulas. The Barrett Universal II formulas yielded the highest percentage of eyes within ±1.0 D and ±0.5 D of the target refraction in this study (97.24% and 79.56%, resp.). Conclusions. Barrett Universal II formula produced the lowest predictive error and the least variable predictive error compared with the SRK/T, Haigis, Holladay, and Hoffer Q formulas. For high myopic eyes, the Barrett Universal II formula may be a more suitable choice.

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 ±â€Š14.4 years, with 4 females and 15 males. Two patients required secondary filtration procedure. At 6 months, the IOP reduced by 34.8% (24.4 ±â€Š4.4 mm Hg to 15.9 ±â€Š5.1 mm Hg, P < 0.0001). The number of types of antiglaucoma medications was reduced by 28.2% (3.9 ±â€Š0.8-2.8 ±â€Š1.6, 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.

Assessment of corneal biomechanical parameters in myopes and emmetropes using the Corvis ST.

BACKGROUND: Prior studies have demonstrated conflicting results regarding the relationship between corneal biomechanical properties and refractive error. Thus, the purpose of this study was to compare the corneal biomechanical parameters of myopes and emmetropes. METHODS: Ninety-four subjects with varying degrees of myopia (aged 29 to 74 years, spherical equivalent [SE] -0.5 to -17.5 D) and 25 emmetropes (aged 19 to 75 years, SE: -0.5 to +0.5 D) presenting at the Queen Mary Hospital, Hong Kong were recruited sequentially for this prospective study. All patients were phakic with no history of coexisting ocular disease. The corneal biomechanical parameters of the right eye of each subject were analysed using the Corvis ST non-contact tonometer. Intraocular pressure (IOP) was measured using both the Corvis ST and the Topcon Non-Contact Tonometer CT-80. Refractive error was measured by non-cycloplegic subjective and objective refractometry. RESULTS: High myopes (SE greater than -6.00 D) demonstrated greater mean outward applanation velocities (p < 0.001) and peak distance measurements (p = 0.009) compared to both low to moderate myopes (SE -0.50 to -6.00 D) and emmetropes. Both outward applanation velocity and peak distance were moderately correlated with refractive error (p ≤ 0.001), strongly correlated with IOP and weakly correlated with central corneal thickness. There were no statistically significant differences in age, IOP or central corneal thickness among emmetropes, low to moderate myopes or high myopes. CONCLUSION: Within this study of Chinese subjects, high myopes demonstrate greater corneal mean outward applanation velocity on Corvis ST testing, than emmetropes. In particular, those with high myopia (SE greater than -6.00 D) show a distinct corneal biomechanical profile relative to those with either emmetropia or low to moderate myopia using the Corvis ST.

Correlation of Intraocular Pressure Between Both Eyes After Bilateral Selective Laser Trabeculoplasty in Open-angle Glaucoma.

PURPOSE: To investigate the correlation of intraocular pressure (IOP)-lowering effects of selective laser trabeculoplasty (SLT) between the 2 eyes treated with SLT in open-angle glaucoma (OAG). METHODS: This prospective cohort study sequentially recruited subjects with bilateral OAG. All subjects received a single session of 360-degree SLT treatment. Success was defined as IOP reduction of ≥20%. Spearman correlation was used to compare the following parameters between the 2 eyes following SLT: IOP at day 1, 1 week, and 1 month; percentage of success; and IOP reduction. RESULTS: In 84 eyes of 42 subjects that received bilateral SLT treatment, both eyes had statistically comparable baseline characteristics. There were significant correlations between the IOP in both eyes at all time intervals following SLT as well as for the percentage of IOP reduction and the success rate at 1 month after SLT (all r≥0.7, P<0.0001). A total of 42.9% of subjects had bilateral success and 38.1% had bilateral nonsuccess with a significant correlation between both eyes in these 2 groups (Spearman r>0.6, P<0.02). Nineteen percent had success in 1 eye and nonsuccess in the fellow eye with an inverse correlation between the 2 eyes (Spearman r=-0.7, P=0.03). CONCLUSION: There is a strong and significant correlation in the IOP-lowering response to SLT between both eyes in near 80% of treated OAG subjects, whereas near 20% had an asymmetrical and inverse response to SLT between both the eyes.

Developments in laser trabeculoplasty.

Laser trabeculoplasty has an increasing important role in the management of glaucoma as more emphasis is placed on minimally invasive therapies. In recent years, the following laser trabeculoplasty technologies have been introduced: micropulse laser trabeculoplasty, titanium-sapphire laser trabeculoplasty and pattern scanning trabeculoplasty. These lasers help to reduce the intraocular pressure (IOP) and the burden of glaucoma medical therapy. Literature findings regarding the safety and efficacy of these newer forms of laser trabeculoplasty in the treatment of open-angle glaucoma is summarised. These relatively newer procedures appear to have similar efficacy when compared with the former selective laser trabeculoplasty or argon laser trabeculoplasty. In addition, they potentially offer a more favourable safety profile with fewer complications, including postlaser inflammation and IOP spikes. Further large-scale studies are necessary to evaluate the long-term benefits of these newer forms of laser trabeculoplasty. Their initial promising results offer patients with glaucoma additional treatment alternatives.

Novel Parameter of Corneal Biomechanics That Differentiate Normals From Glaucoma.

PURPOSE: To identify novel corneal biomechanical parameters differentiating glaucomatous from normal eyes. PATIENTS AND METHODS: Sixty subjects with varying degrees of glaucoma severity and 61 normal controls underwent corneal biomechanical measurements including corneal deformation amplitude, inward and outward applanation length and velocity, and highest concavity time in 1 eye per subject at Queen Mary Hospital, Hong Kong. Measurements were taken with the Corvis ST device, a noncontact tonometer coupled with a high-speed Scheimpflug camera. The intraocular pressure (IOP) and central corneal thickness (CCT) were also measured. RESULTS: Significant findings included differences in outward applanation velocity (glaucoma: -0.37±0.01 m/s; control: -0.32±0.01 m/s; P=0.001), peak distance (glaucoma: 2.37±0.03 mm; control: 2.30±0.02 mm; P=0.005), and highest concavity time (glaucoma: 16.75±0.08 ms; control: 17.05±0.07 ms; P=0.002) between the 2 groups, after correcting for IOP, CCT, and age. Both outward applanation velocity and peak distance were moderately correlated with IOP and CCT. However, highest concavity time was not correlated with either IOP or CCT (R(2)=0.0140 and 0.000055, respectively). Age was not correlated with any of the 3 parameters. CONCLUSIONS: Glaucomatous eyes have a greater mean outward applanation velocity and peak distance, but shorter time to highest concavity than eyes without glaucoma. The difference in time to highest concavity does not correlate with age, IOP, or CCT, suggesting that this parameter may be a marker of increased pressure susceptibility that is independently associated with glaucoma risk.

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

The 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 Bonferroni's 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 ±â€Š2.0 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 (P's > 0.5). The IOP and number of medications were significantly reduced at all time intervals following MLT compared to the pre-MLT level (P's < 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.

Central Macular Thickness in Children with Myopia, Emmetropia, and Hyperopia: An Optical Coherence Tomography Study.

PURPOSE: To investigate the central macular thickness (CMT) in myopic, emmetropic, and hyperopic Chinese children using Optical Coherence Tomography. METHODS: 168 right eyes of Chinese subjects aged 4-18 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) and the CMT was compared before/after age adjustment. The CMT was correlated with age, axial length, and peripapillary retinal nerve fibre layer (RNFL). RESULTS: The mean CMT was 274.9 ± 50.3 µm and the mean population age was 7.6 ± 3.3 years. The CMT was thickest in the myopes (283.3 ± 57.3 µm, n = 56), followed by the hyperopes (266.2 ± 55.31 µm, n = 60) and then emmetropes (259.8 ± 28.7 µm, n = 52) (all P < 0.0001). When adjusted for age, myopes had a thicker CMT than the other 2 groups (all P < 0.0001) but there was no CMT difference between the emmetropes and hyperopes (P > 0.05). There was no significant correlation between CMT with age, axial length, or peripapillary RNFL (all P ≥ 0.2). CONCLUSION: Chinese children with myopia had a thicker CMT than those with emmetropia or hyperopia. There was no correlation of the CMT with age, axial length, or peripapillary RNFL thickness.

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 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.

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

UNLABELLED: 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).

Corneal collagen cross-linking for infectious keratitis: an update of clinical studies.

Collagen cross-linking (CXL) with ultraviolet light-activated riboflavin is a corneal surface procedure developed for the treatment of keratoconus and corneal ectasia. With the known microbicidal and corneal stiffening effects of ultraviolet irradiation and photoactivated riboflavin, it has recently been introduced for the management of infectious keratitis, especially for ulcers resistant to antimicrobial therapy or associated with corneal melting. Various authors have attempted to use CXL as an adjunctive, salvage or even as the sole treatment for infectious corneal ulcers. The aim of this review was to provide a summary of the clinical studies in the literature. It is worth noting that there is still no consensus on the treatment protocol of CXL against infectious keratitis. The disparities in outcome measures, treatment protocol and study design can confound the interpretation and hamper the generalization of the study results. Based on current evidence, the role of CXL in infectious keratitis remained unclear despite the reported success in some clinical cases. Further investigations are warranted concerning the efficacy and safety of treating infectious keratitis with CXL.