Simon Chen | The University of New South Wales (original) (raw)

Papers by Simon Chen

Retinal cases & brief reports, Jan 10, 2017

To report a case of a branch retinal vein occlusion secondary to a retinal arteriolar macroaneury... more To report a case of a branch retinal vein occlusion secondary to a retinal arteriolar macroaneurysm (RAM). Retrospective case report describing examination findings, treatment outcome and unique multimodal imaging features demonstrated on fluorescein angiography, optical coherence tomography, optical coherence tomography angiography and adaptive optics photography of the retinal vessels and RAM. A 61-year-old man presented with 20/200 vision in the right eye because of a branch retinal vein occlusion secondary to a RAM. After sector panretinal photocoagulation and a course of 24 intravitreal antivascular endothelial growth factor injections over 4 years, visual acuity improved to 20/25. Fluorescein angiography showed filling of the RAM even after 4 years. Optical coherence tomography angiography demonstrated venous collateral vessels in both the superficial and deep capillary plexuses, and adaptive optics imaging revealed a gap between the RAM wall and occluded vein. Multimodal imag...

Journal of refractive surgery (Thorofare, N.J. : 1995), 2014

To describe a case of lacquer cracks developing after phakic intraocular lens implantation. Case ... more To describe a case of lacquer cracks developing after phakic intraocular lens implantation. Case report. A 46-year-old woman diagnosed as having extreme myopia and corrected distance visual acuity of 20/40 presented with decreased vision and a central scotoma less than 24 hours following phakic intraocular lens implantation. Dilated examination revealed the presence of a macular hemorrhage and possible lacquer crack formation. Documented preoperative imaging showed an absence of lacquer cracks in the eye that was operated on. The patient was treated with intravitreal bevacizumab. At 4 weeks postoperatively, imaging confirmed an almost complete resolution of the hemorrhagic pigment epithelial detachment with evidence of lacquer cracks. Uncorrected visual acuity was 20/50 and the patient was asymptomatic. This is the first reported case of macular crack formation immediately following phakic intraocular lens implantation. Possible contributing factors are discussed.

American Journal of Ophthalmology, 2015

To investigate the presence of TBK1 copy number variations in a large, well-characterized Austral... more To investigate the presence of TBK1 copy number variations in a large, well-characterized Australian cohort of patients with glaucoma comprising both normal-tension glaucoma and high-tension glaucoma cases. A retrospective cohort study. DNA samples from patients with normal-tension glaucoma and high-tension glaucoma and unaffected controls were screened for TBK1 copy number variations using real-time quantitative polymerase chain reaction. Samples with additional copies of the TBK1 gene were further tested using custom comparative genomic hybridization arrays. Four out of 334 normal-tension glaucoma cases (1.2%) were found to carry TBK1 copy number variations using quantitative polymerase chain reaction. One extra dose of the TBK1 gene (duplication) was detected in 3 normal-tension glaucoma patients, while 2 extra doses of the gene (triplication) were detected in a fourth normal-tension glaucoma patient. The results were further confirmed by custom comparative genomic hybridization arrays. Further, the TBK1 copy number variation segregated with normal-tension glaucoma in the family members of the probands, showing an autosomal dominant pattern of inheritance. No TBK1 copy number variations were detected in 1045 Australian patients with high-tension glaucoma or in 254 unaffected controls. We report the presence of TBK1 copy number variations in our Australian normal-tension glaucoma cohort, including the first example of more than 1 extra copy of this gene in glaucoma patients (gene triplication). These results confirm TBK1 to be an important cause of normal-tension glaucoma, but do not suggest common involvement in high-tension glaucoma.

Oxford Medicine Online, 2009

This resource takes a fresh approach to ophthalmology training and is the first to take account o... more This resource takes a fresh approach to ophthalmology training and is the first to take account of the new ophthalmic training structure and syllabus. It is a theoretical and practical aid for ophthalmologists to use and progress through the initial years of the new postgraduate Ophthalmic Specialist Training.

Eye

To the Editor: Recently, Bohler et al., described the first report of acute macular neuroretinopa... more To the Editor: Recently, Bohler et al., described the first report of acute macular neuroretinopathy (AMN) following Vaxzevria (formerly ChAdOx1 nCoV-19, Oxford-AstraZeneca, UK) providing a possible causal association with COVID-19 innoculation [1]. Through mid 2021, there are 5 reported cases of AMN following vaccination with Vaxzevria [1-4]. We describe the first AMN case following use of an alternate mRNA vaccine. A 21-year-old Caucasian female was referred for assessment of ongoing left paracentral scotomas. Her only medication was a combined oral contraceptive (ethinylestradiol 0.02mg-levonorgestrel 0.1mg). Ten weeks previously she had received her first COVID-19 vaccine injection (BNT162b2 mRNA, Pfizer-BioNTech). Three days post-injection, she developed acute chills, myalgia, headache and two left scotomas either side of fixation. Systemic symptoms resolved quickly. The patient reported a gradual decrease in scotoma intensity with time. Uncorrected visual acuity was 6/6 bilaterally and right eye examination normal. Left fundus examination demonstrated

Cataract surgery remains the most widely performed intraocular procedure throughout the world. Sa... more Cataract surgery remains the most widely performed intraocular procedure throughout the world. Safety and accuracy of the procedure are paramount and techniques should remain under constant review. Recently, the introduction of the femtosecond laser to assist cataract surgery has provided ophthalmologists with an exciting tool that may further improve outcomes. We review the existing literature and discuss the installation and initial experience of a femtosecond laser into our practice.

PURPOSE: To investigate the molecular mechanism by which triamcinolone acetonide (TA) may reduce ... more PURPOSE: To investigate the molecular mechanism by which triamcinolone acetonide (TA) may reduce edema in a porcine model of branch retinal vein occlusion (BRVO).

American Journal of Ophthalmology

PURPOSE: To evaluate the safety and efficacy of intravitreal triamcinolone acetonide (IVTA) for i... more PURPOSE: To evaluate the safety and efficacy of intravitreal triamcinolone acetonide (IVTA) for ischemic macular edema associated with branch retinal vein occlusion (BRVO) and foveal ischemia. • DESIGN: Prospective interventional case series. • METHODS: SETTING: Clinical practice. STUDY POPULA-TION: Eighteen eyes of 18 patients with macular edema associated with BRVO and foveal ischemia. INTERVEN-TION: Four mg IVTA. MAIN OUTCOME MEASURES: Visual acuity (VA), optical coherence tomography, macular thickness measurements, and treatment-related complications.

M alignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery ... more M alignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery in eyes with primary angle closure. Pars plana vitrectomy is reserved for the treatment of malignant glaucoma when medical and laser treatment fail. The primary aim of surgery is the removal of the anterior vitreous to reduce resistance to aqueous flow into the anterior chamber. In phakic eyes, conventional pars plana vitrectomy without lens extraction is frequently unsuccessful because of difficulty visualizing the normally transparent anterior vitreous, combined with the technical challenge of removing the anterior vitreous without damaging the crystalline lens. We describe a technique of intraocular, videoendoscope-guided, fluorescein-assisted pars plana vitrectomy that enables direct visualization and thorough removal of the anterior vitreous without the need for lens extraction in prepresbyopic patients without cataract.

Eye

Eye 2 Sarraf D, Payne AM, Kitchen ND, Sehmi K, Downes SM, Bird AC. Cavernous hemangioma: an expan... more Eye 2 Sarraf D, Payne AM, Kitchen ND, Sehmi K, Downes SM, Bird AC. Cavernous hemangioma: an expanding ocular spectrum.

Eye

Purpose To evaluate the safety and efficacy of sub-Tenon's local anaesthesia (LA) for laser treat... more Purpose To evaluate the safety and efficacy of sub-Tenon's local anaesthesia (LA) for laser treatment of threshold retinopathy of prematurity (ROP). Methods A cohort of 18 eyes of 10 neonates with threshold ROP was treated with diode laser peripheral retinal ablation over 14 treatment sessions using oral sedation and sub-Tenon's anaesthesia. Treatment was performed in a neonatal unit. The heart and respiratory rate, trans-cutaneous oxygen saturation, and physical activity were continuously monitored for signs of neonatal distress. Cardio-respiratory stability during and after the procedure was scored for each eye treated using a Cardio-respiratory index described previously.

Retinal cases & brief reports, Jan 10, 2017

To report a case of a branch retinal vein occlusion secondary to a retinal arteriolar macroaneury... more To report a case of a branch retinal vein occlusion secondary to a retinal arteriolar macroaneurysm (RAM). Retrospective case report describing examination findings, treatment outcome and unique multimodal imaging features demonstrated on fluorescein angiography, optical coherence tomography, optical coherence tomography angiography and adaptive optics photography of the retinal vessels and RAM. A 61-year-old man presented with 20/200 vision in the right eye because of a branch retinal vein occlusion secondary to a RAM. After sector panretinal photocoagulation and a course of 24 intravitreal antivascular endothelial growth factor injections over 4 years, visual acuity improved to 20/25. Fluorescein angiography showed filling of the RAM even after 4 years. Optical coherence tomography angiography demonstrated venous collateral vessels in both the superficial and deep capillary plexuses, and adaptive optics imaging revealed a gap between the RAM wall and occluded vein. Multimodal imag...

Journal of refractive surgery (Thorofare, N.J. : 1995), 2014

To describe a case of lacquer cracks developing after phakic intraocular lens implantation. Case ... more To describe a case of lacquer cracks developing after phakic intraocular lens implantation. Case report. A 46-year-old woman diagnosed as having extreme myopia and corrected distance visual acuity of 20/40 presented with decreased vision and a central scotoma less than 24 hours following phakic intraocular lens implantation. Dilated examination revealed the presence of a macular hemorrhage and possible lacquer crack formation. Documented preoperative imaging showed an absence of lacquer cracks in the eye that was operated on. The patient was treated with intravitreal bevacizumab. At 4 weeks postoperatively, imaging confirmed an almost complete resolution of the hemorrhagic pigment epithelial detachment with evidence of lacquer cracks. Uncorrected visual acuity was 20/50 and the patient was asymptomatic. This is the first reported case of macular crack formation immediately following phakic intraocular lens implantation. Possible contributing factors are discussed.

American Journal of Ophthalmology, 2015

To investigate the presence of TBK1 copy number variations in a large, well-characterized Austral... more To investigate the presence of TBK1 copy number variations in a large, well-characterized Australian cohort of patients with glaucoma comprising both normal-tension glaucoma and high-tension glaucoma cases. A retrospective cohort study. DNA samples from patients with normal-tension glaucoma and high-tension glaucoma and unaffected controls were screened for TBK1 copy number variations using real-time quantitative polymerase chain reaction. Samples with additional copies of the TBK1 gene were further tested using custom comparative genomic hybridization arrays. Four out of 334 normal-tension glaucoma cases (1.2%) were found to carry TBK1 copy number variations using quantitative polymerase chain reaction. One extra dose of the TBK1 gene (duplication) was detected in 3 normal-tension glaucoma patients, while 2 extra doses of the gene (triplication) were detected in a fourth normal-tension glaucoma patient. The results were further confirmed by custom comparative genomic hybridization arrays. Further, the TBK1 copy number variation segregated with normal-tension glaucoma in the family members of the probands, showing an autosomal dominant pattern of inheritance. No TBK1 copy number variations were detected in 1045 Australian patients with high-tension glaucoma or in 254 unaffected controls. We report the presence of TBK1 copy number variations in our Australian normal-tension glaucoma cohort, including the first example of more than 1 extra copy of this gene in glaucoma patients (gene triplication). These results confirm TBK1 to be an important cause of normal-tension glaucoma, but do not suggest common involvement in high-tension glaucoma.

Oxford Medicine Online, 2009

This resource takes a fresh approach to ophthalmology training and is the first to take account o... more This resource takes a fresh approach to ophthalmology training and is the first to take account of the new ophthalmic training structure and syllabus. It is a theoretical and practical aid for ophthalmologists to use and progress through the initial years of the new postgraduate Ophthalmic Specialist Training.

Eye

To the Editor: Recently, Bohler et al., described the first report of acute macular neuroretinopa... more To the Editor: Recently, Bohler et al., described the first report of acute macular neuroretinopathy (AMN) following Vaxzevria (formerly ChAdOx1 nCoV-19, Oxford-AstraZeneca, UK) providing a possible causal association with COVID-19 innoculation [1]. Through mid 2021, there are 5 reported cases of AMN following vaccination with Vaxzevria [1-4]. We describe the first AMN case following use of an alternate mRNA vaccine. A 21-year-old Caucasian female was referred for assessment of ongoing left paracentral scotomas. Her only medication was a combined oral contraceptive (ethinylestradiol 0.02mg-levonorgestrel 0.1mg). Ten weeks previously she had received her first COVID-19 vaccine injection (BNT162b2 mRNA, Pfizer-BioNTech). Three days post-injection, she developed acute chills, myalgia, headache and two left scotomas either side of fixation. Systemic symptoms resolved quickly. The patient reported a gradual decrease in scotoma intensity with time. Uncorrected visual acuity was 6/6 bilaterally and right eye examination normal. Left fundus examination demonstrated

Cataract surgery remains the most widely performed intraocular procedure throughout the world. Sa... more Cataract surgery remains the most widely performed intraocular procedure throughout the world. Safety and accuracy of the procedure are paramount and techniques should remain under constant review. Recently, the introduction of the femtosecond laser to assist cataract surgery has provided ophthalmologists with an exciting tool that may further improve outcomes. We review the existing literature and discuss the installation and initial experience of a femtosecond laser into our practice.

PURPOSE: To investigate the molecular mechanism by which triamcinolone acetonide (TA) may reduce ... more PURPOSE: To investigate the molecular mechanism by which triamcinolone acetonide (TA) may reduce edema in a porcine model of branch retinal vein occlusion (BRVO).

American Journal of Ophthalmology

PURPOSE: To evaluate the safety and efficacy of intravitreal triamcinolone acetonide (IVTA) for i... more PURPOSE: To evaluate the safety and efficacy of intravitreal triamcinolone acetonide (IVTA) for ischemic macular edema associated with branch retinal vein occlusion (BRVO) and foveal ischemia. • DESIGN: Prospective interventional case series. • METHODS: SETTING: Clinical practice. STUDY POPULA-TION: Eighteen eyes of 18 patients with macular edema associated with BRVO and foveal ischemia. INTERVEN-TION: Four mg IVTA. MAIN OUTCOME MEASURES: Visual acuity (VA), optical coherence tomography, macular thickness measurements, and treatment-related complications.

M alignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery ... more M alignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery in eyes with primary angle closure. Pars plana vitrectomy is reserved for the treatment of malignant glaucoma when medical and laser treatment fail. The primary aim of surgery is the removal of the anterior vitreous to reduce resistance to aqueous flow into the anterior chamber. In phakic eyes, conventional pars plana vitrectomy without lens extraction is frequently unsuccessful because of difficulty visualizing the normally transparent anterior vitreous, combined with the technical challenge of removing the anterior vitreous without damaging the crystalline lens. We describe a technique of intraocular, videoendoscope-guided, fluorescein-assisted pars plana vitrectomy that enables direct visualization and thorough removal of the anterior vitreous without the need for lens extraction in prepresbyopic patients without cataract.

Eye

Eye 2 Sarraf D, Payne AM, Kitchen ND, Sehmi K, Downes SM, Bird AC. Cavernous hemangioma: an expan... more Eye 2 Sarraf D, Payne AM, Kitchen ND, Sehmi K, Downes SM, Bird AC. Cavernous hemangioma: an expanding ocular spectrum.

Eye

Purpose To evaluate the safety and efficacy of sub-Tenon's local anaesthesia (LA) for laser treat... more Purpose To evaluate the safety and efficacy of sub-Tenon's local anaesthesia (LA) for laser treatment of threshold retinopathy of prematurity (ROP). Methods A cohort of 18 eyes of 10 neonates with threshold ROP was treated with diode laser peripheral retinal ablation over 14 treatment sessions using oral sedation and sub-Tenon's anaesthesia. Treatment was performed in a neonatal unit. The heart and respiratory rate, trans-cutaneous oxygen saturation, and physical activity were continuously monitored for signs of neonatal distress. Cardio-respiratory stability during and after the procedure was scored for each eye treated using a Cardio-respiratory index described previously.