Browsing by Author "Materin, Miguel A"
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Item Open Access Assessment of Macular Microvasculature in Healthy Eyes of Infants and Children Using OCT Angiography.(Ophthalmology, 2019-12) Hsu, S Tammy; Ngo, Hoan T; Stinnett, Sandra S; Cheung, Nathan L; House, Robert J; Kelly, Michael P; Chen, Xi; Enyedi, Laura B; Prakalapakorn, S Grace; Materin, Miguel A; El-Dairi, Mays A; Jaffe, Glenn J; Freedman, Sharon F; Toth, Cynthia A; Vajzovic, LejlaPURPOSE:To assess macular vasculature in healthy infants and children using OCT angiography (OCTA). DESIGN:Prospective cross-sectional study. PARTICIPANTS:One hundred thirty-five normal maculae of 89 healthy infants and children (mean age, 8.5±5.3 years; range, 9 weeks-17 years) treated at the Duke University Eye Center. METHODS:We imaged 135 maculae of 89 pediatric patients using the standard Spectralis tabletop and investigational Spectralis with Flex module devices, both equipped with investigational OCTA software (Heidelberg Engineering, Heidelberg, Germany). OCT angiography images of the superficial vascular complex (SVC) and deep vascular complex (DVC) were analyzed for foveal avascular zone (FAZ) area and superficial and deep vessel density. We assessed effects of age, gender, race, axial length (AL), and central subfield thickness on FAZ and vessel density. Patients with both eyes imaged were assessed for agreement between the FAZ and vessel densities of the left and right eyes. MAIN OUTCOME MEASURES:The FAZ area, as well as vessel area density (VAD) and vessel length density (VLD) in the SVC and DVC. RESULTS:The FAZ varied significantly with race; white patients showed a significantly smaller FAZ than black patients (mean difference, 0.11 mm2; P = 0.004). The FAZ did not vary with age, gender, or AL (P > 0.05). In the SVC, VAD and VLD varied significantly with age (P < 0.001) and AL (R2 = 0.46; P < 0.001) but not gender (P > 0.05). The SVC VLD was significantly different between races and ethnicities (P = 0.037), but VAD was not (P < 0.05). In the DVC, VAD and VLD also varied significantly with age (P < 0.001) and AL (R2 = 0.46; P < 0.001) but not gender or race (P > 0.05). There was excellent agreement between the right and left eyes for FAZ (intraclass correlation [ICC], 0.97), SVC VLD (ICC, 1.00), and DVC VLD (ICC, 1.00). CONCLUSIONS:Quantitative studies of pediatric perifoveal vasculature should consider age, race, and AL. In eyes with unilateral disease, the perifoveal vasculature in the unaffected eye may be used as a control comparison because there is excellent agreement between eyes.Item Open Access Dual-source strength seed loading for eye plaque brachytherapy using eye physics eye plaques: A feasibility study.(Journal of contemporary brachytherapy, 2022-12) Meltsner, Sheridan G; Kirsch, David G; Materin, Miguel A; Kim, Yongbok; Sheng, Yang; Craciunescu, OanaPurpose
This study quantifies the dosimetric impact of incorporating two iodine-125 (125I) seed source strengths in Eye Physics eye plaques for treatment of uveal melanoma.Material and methods
Plaque Simulator was used to retrospectively plan 15 clinical cases of three types: (1) Shallow tumors (< 5.5 mm) with large base dimensions (range, 16-19 mm); (2) Tumors near the optic nerve planned with notched plaques; and (3) Very shallow (< 3.0 mm) tumors with moderate base dimensions (range, 13.5-15.5 mm) planned with larger plaques than requested by the ocular oncologist. Circular plaques were planned with outer ring sources twice the source strength of inner sources, and notched plaques with the six seeds closest to the notch at twice the source strength.Results
In cases of type (1), the dual-source strength plan decreased prescription depth, and doses to critical structures were lower: inner sclera -25% ±2%, optic disc -7% ±3%, and fovea -6% ±3%. In four out of five cases of type (2), the dual-source strength plan decreased prescription depth, and dose to inner sclera was lower (-22% ±5%), while dose to optic disc (17% ±7%) and fovea (20% ±12%) increased. In cases of type (3), a smaller dual-source strength plaque was used, and scleral dose was lower (-45% ±3%), whereas dose to optic disc (1% ±14%) and fovea (5% ±5%) increased.Conclusions
Dual-source strength loading as described in this study can be used to cover tumor margins and decrease dose to sclera, and therefore the adjacent retina, but can either decrease or increase radiation dose to optic disc and fovea depending on location and size of the tumor. This technique may allow the use of a smaller plaque, if requested by the ocular oncologist. Clinical determination to use this technique should be performed on an individual basis, and additional QA steps are required. Integrating the use of volumetric imaging may be warranted.