301 University Blvd. Utmb, Ophthalmology And Visual Sciences
Galveston TX 77555
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Optical Coherence Tomography Angiography of Diabetic Retinopathy in Human Subjects. - Ophthalmic surgery, lasers & imaging retina
Optical coherence tomography angiography (OCTA) is a novel, non-invasive OCT technique capable of imaging the retinal vasculature. This study aims to evaluate the retinal microvasculature in diabetic human subjects with OCTA and assess potential clinical applications.Cross-sectional study of 33 subjects with diabetic retinopathy. OCTA was performed on 3 mm Ã— 3 mm sections using a swept-source OCTA prototype and a phase- and intensity-based contrasting algorithm. OCT angiograms were studied with corresponding clinical examination and fluorescein angiograms, when available, to assess accuracy and clinical utility.OCTA was able to demonstrate most clinically relevant vascular changes in subjects with diabetic retinopathy, including microaneurysms, impaired vascular perfusion, some forms of intraretinal fluid, vascular loops, intraretinal microvascular abnormalities, neovascularization, and cotton-wool spots that were largely consistent with fluorescein angiography.OCTA generates high-resolution angiograms that illustrate many of the clinically relevant findings in diabetic retinopathy and offers a novel complement or alternative to fluorescein angiography. Although currently an investigational technique, OCTA in combination with standard OCT imaging is at least as good as fluorescein angiography in the evaluation of the macular complications of diabetic retinopathy.Copyright 2015, SLACK Incorporated.
MULTIMODAL IMAGING OF GEOGRAPHIC AREAS OF RETINAL DARKENING. - Retinal cases & brief reports
To describe the clinical and multimodal imaging characteristics of a patient with unilateral asymptomatic dark retinal lesions corresponding to ellipsoid zone hyporeflectivity on optical coherence tomography (OCT).The authors report a case of a 35-year-old man with HIV who presents with asymptomatic dark geographic retinal lesions corresponding to ellipsoid zone hyporeflectivity on OCT. Multimodal imaging techniques, including fundus color and widefield photographs, autofluorescence, spectral domain OCT (Spectralis, Heidelberg, Germany), prototype spectral domain OCT (Carl Zeiss Meditec, Dublin, CA) with OCT angiography, and en face images, were performed to evaluate and characterize the morphology of these lesions.Clinical examination and multimodal imaging reveal geographic darkening of the retina. Optical coherence tomography conveys hyporeflectivity of the ellipsoid zone band, which occurs abruptly and is present only in the areas of geographic retinal darkening. Optical coherence tomographic angiography shows a qualitatively similar appearance of the vasculature from the superficial retina through the avascular retina and the choriocapillaris, on both sides of the demarcation of retinal darkening, and also as compared to the unaffected eye. En face images from spectral domain OCT reveal an abrupt darkening of the tissue that localizes and is limited to the ellipsoid zone, with similar topographic appearance across the demarcation line.Geographic areas of darkening with photoreceptor hyporeflectivity have been described previously as "dark without pressure." In this case, the authors demonstrate photoreceptor hyporeflectivity that localizes to the clinically darkened areas, without topographic qualitative differences on en face spectral domain OCT images. The authors term these dark areas as geographic areas of retinal darkening because of ellipsoid nonreflectivity (GARDEN) spots.
Type 3 neovascularization: evolution, association with pigment epithelial detachment, and treatment response as revealed by spectral domain optical coherence tomography. - Retina (Philadelphia, Pa.)
To demonstrate the evolution and treatment response of Type 3 neovascularization using spectral domain optical coherence tomography.We retrospectively analyzed 40 eyes treated with intravitreal anti-vascular endothelial growth factor therapy for Type 3 neovascularization over a variable follow-up period.In 17 eyes, spectral domain optical coherence tomography captured the development of Type 3 neovascularization from punctate hyperreflective foci that preceded any outer retinal defect. The more mature Type 3 lesions were associated with outer retinal disruption and adjacent cystoid macular edema. In addition, 37 of 40 Type 3 lesions (93%) were associated with an underlying pigment epithelial detachment, of which 26 (70%) were drusenoid, 6 (16%) serous, and 5 (14%) mixed. Type 3 vessels appeared to leak fluid into the pigment epithelial detachment cavity, creating serous pigment epithelial detachments as large as 925 Î¼m in maximal height. Treatment with anti-vascular endothelial growth factor agents led to prompt involution of the lesion and resorption of the intraretinal and subretinal pigment epithelium fluid after one or two injections (median = 1).In some eyes with age-related macular degeneration, the earliest sign of Type 3 neovascularization is punctate hyperreflective foci above the external limiting membrane. The mature Type 3 lesions and associated serous pigment epithelial detachments are highly responsive to anti-vascular endothelial growth factor therapy.
TWEAK/Fn14 pathway is a novel mediator of retinal neovascularization. - Investigative ophthalmology & visual science
Retinal neovascularization (NV) is a major cause of vision loss in ischemia-induced retinopathy. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor inducible-14 (Fn14), have been implicated in angiogenesis, but their role in retinal diseases is unknown. The goal of this study was to investigate the role of TWEAK/Fn14 pathway in retinal NV.Studies were performed in a mouse model of oxygen-induced retinopathy (OIR) and in primary human retinal microvascular endothelial cells (HRMECs). Hyperoxia treatment was initiated on postnatal day (P)14. Immunohistochemistry and quantitative PCR (qPCR) were used to assess retinal vascular changes in relation to expression of Fn14 and TWEAK.Fibroblast growth factor-inducible 14 mRNA was prominently increased from P13 to P17 in OIR retinas, whereas TWEAK level was slightly decreased. These alterations were normalized by hyperoxia treatment and were more striking in isolated retinal vessels. There was a discernible shift in the immunoreactivity of Fn14 and TWEAK from the neuronal layers in the healthy retina to the neovascular tufts in that of OIR. Blockade of TWEAK/Fn14 significantly prevented retinal NV while slightly accelerated revascularization. In contrast, activation of Fn14 positively regulated survival pathways in the B-cell lymphoma-2 (Bcl2) family and robustly enhanced HRMEC survival. Furthermore, gene analysis revealed the regulatory region of Fn14 gene contains several conserved hypoxia inducible factor (HIF)-1Î± binding sites. Overexpression of HIF-1Î± prominently induced Fn14 expression in HRMECs.We found that the TNF-like weak inducer of apoptosis (TWEAK)/fibroblast growth factor inducible-14 (Fn14) pathway is involved in the development of pathologic retinal neovascularization. Hypoxia inducible factor-1Î± is likely implicated in the upregulation of Fn14.
Vitreal oxygenation in retinal ischemia reperfusion. - Investigative ophthalmology & visual science
To study the feasibility of anterior vitreal oxygenation for the treatment of acute retinal ischemia.Twenty rabbits were randomized into an oxygenation group, a sham treatment group, and a no treatment group. Baseline electroretinography (ERG) and preretinal oxygen (Po(2)) measurements were obtained 3 to 5 days before surgery. Intraocular pressure was raised to 100 mm Hg for 90 minutes and then normalized. The oxygenation group underwent vitreal oxygenation for 30 minutes using intravitreal electrodes. The sham treatment group received inactive electrodes for 30 minutes while there was no intervention for the no treatment group. Preretinal Po(2) in the posterior vitreous was measured 30 minutes after intervention or 30 minutes after reperfusion (no treatment group) and on postoperative days (d) 3, 6, 9, and 12. On d14, rabbits underwent ERG and were euthanatized.Mean final (d12) Po(2) was 10.64 Â± 0.77 mm Hg for the oxygenation group, 2.14 Â± 0.61 mm Hg for the sham group, and 1.98 Â± 0.63 mm Hg for the no treatment group. On ERG, scotopic b-wave amplitude was significantly preserved in the oxygenation group compared with the other two groups. Superoxide dismutase assay showed higher activity in the operated eyes than in the nonoperated control eyes in the sham treatment group and no treatment group only. Histopathology showed preservation of retinal architecture and choroidal vasculature in the oxygenation group, whereas the sham-treated and nontreated groups showed retinal thinning and choroidal atrophy.In severe total ocular ischemia, anterior vitreal oxygenation supplies enough oxygen to penetrate the retinal thickness, resulting in rescue of the RPE/choriocapillaris that continues to perfuse, hence sparing the retinal tissue from damage.
Neuroretinitis with retrobulbar involvement. - Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society
Two patients with neuroretinitis are presented, both having MRI abnormalities of the orbital portion of the optic nerve. We review previous reports of CT and MRI findings in patients with neuroretinitis and propose a spectrum of neuroimaging abnormalities in these patients.
Ultrasonic Doppler measurements of blood flow velocity of rabbit retinal vessels using a 45-MHz needle transducer. - Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fuÌˆr klinische und experimentelle Ophthalmologie
The purpose of this study is to measure blood flow velocity of rabbit retinal vessels using a 45-MHz ultrasonic Doppler system with a needle transducer.A high-frequency pulsed Doppler system that utilizes a 45-MHz PMN-PT needle transducer was developed to measure retinal blood flow velocity in situ. The pulsed Doppler allowed the differentiation of retinal from choroidal blood flow velocity. The needle transducer was inserted into the vitreous cavity through a 20-gauge incision port to access the retinal vessels. The first phase of the experiment evaluated the reproducibility of the measurements. The second phase measured velocities at four positions from the optic disc edge to the distal part of each vessel in nine eyes for the temporal and six eyes for the nasal portions. The angle between the transducer and the retinal vessel at each site was measured in enucleated rabbit eyes to estimate and compensate for measurement errors.In the first phase, the average measurement error was 5.97 +/- 1.34%. There was no significant difference comparing all eyes. In the second phase, the velocities gradually slowed from the disc edge to the distal part, and temporal velocities were faster than nasal velocities at all measurement sites.This study demonstrated the feasibility of reliably measuring retinal blood flow velocity using a 45-MHz ultrasonic Doppler system with a needle transducer.
Toward a wide-field retinal prosthesis. - Journal of neural engineering
The purpose of this paper is to present a wide field electrode array that may increase the field of vision in patients implanted with a retinal prosthesis. Mobility is often impaired in patients with low vision, particularly in those with peripheral visual loss. Studies on low vision patients as well as simulation studies on normally sighted individuals have indicated a strong correlation between the visual field and mobility. In addition, it has been shown that an increased visual field is associated with a significant improvement in visual acuity and object discrimination. Current electrode arrays implanted in animals or human vary in size; however, the retinal area covered by the electrodes has a maximum projected visual field of about 10 degrees. We have designed wide field electrode arrays that could potentially provide a visual field of 34 degrees, which may significantly improve the mobility. Tests performed on a mechanical eye model showed that it was possible to fix 10 mm wide flexible polyimide dummy electrode arrays onto the retina using a single retinal tack. They also showed that the arrays could conform to the inner curvature of the eye. Surgeries on an enucleated porcine eye model demonstrated feasibility of implantation of 10 mm wide arrays through a 5 mm eye wall incision.
Natural course of experimental retinal vein occlusion in rabbit; arterial occlusion following venous photothrombosis. - Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fuÌˆr klinische und experimentelle Ophthalmologie
Retinal vein occlusion (RVO) is the second leading cause of vascular eye disease. Currently there is no definite treatment for this condition. Animal models could be potentially helpful in developing new treatments; however, it is essential to understand the differences these models may have with human RVO. The aim of our study was to examine the course of experimentally created retinal vein occlusion (RVO) in rabbits.Twenty-nine pigmented rabbits were included in the study. RVO was created in all using an argon green laser following intravenous injection of Rose Bengal. A laser was applied to all major veins at the optic disc margin to mimic central retinal vein occlusion. Animals were followed-up for a maximum of 2 months.Immediately following laser application, blood flow ceased or the flow was extremely slow in the retinal veins in all cases. At day 2 post laser, 86% showed significant retinal hemorrhages. On FA, no retinal blood flow was observed in the eye (neither arteries nor veins) in the majority of rabbits. Between weeks 1 and 3, laser sites reopened and partial or complete revascularization of both retinal arteries and veins occurred; however, the vascular pattern was abnormal.RVO in rabbits has a different course than in human and it can be classified into three stages. At stage 1 (the first few days after laser photothrombosis), there is a retrograde propagation of the blood clot in the retinal veins that extends to the retinal arteries and choriocapillaries. As a result, there is no retinal blood flow at this stage in most cases. At stage 2 (between weeks 1 and 3), partial or complete revascularization occurs but the vessels have an abnormal pattern. At stage 3 (after week 3) no significant change takes place.
Intravitreal and subretinal injection of tissue plasminogen activator (tPA) in the treatment of experimentally created retinal vein occlusion in rabbits. - Retina (Philadelphia, Pa.)
To evaluate the effectiveness of intravitreal or subretinal injection of tPA in the treatment of experimentally created retinal vein occlusion (RVO) in rabbits.Fifteen rabbits were included in this study. RVO was created in all using an argon green laser following intravenous injection of rose Bengal. Follow-up examinations included color fundus photography, fundus fluorescein angiography, and optical coherence tomography. Following examinations at day 2, animals were divided into three groups: six rabbits were kept as control, four rabbits received subretinal injection of tPA, and five rabbits received intravitreal tPA.Of 14 eyes that had capillary drop out at day 2 following creation of RVO, 12 remained the same at week 3. Only one eye in the control group and one eye in the subretinal group developed complete reperfusion of capillaries. Although there was more revascularization in all groups at week 3, there was not a significant difference in the amount of revascularization between the control group and those animals receiving subretinal or intravitreal tPA.Intravitreal or subretinal injection of tPA 2 days following vein occlusion did not improve reperfusion of retinal vessels in experimentally created RVO in rabbits when compared to control group.
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301 University Blvd. Utmb, Ophthalmology And Visual Sciences Galveston, TX 77555
301 University Blvd 4.108 John Sealy Annex