DEPARTMENT OF ophthalmology
A RESEARCH REPORT BY:
Full names: Hamza Miara
TITLE: the changes of RNFL and vessel density in foreign patients with myopic eyes and healthy eyes using optical coherence tomography angiography.
Design: A prospective comparative study was conducted from November 2016 to February 2017
Setting: participants recruited from foreigners from different countries performed by Xiangya second hospital of central south university.
Participants: a total of 80 foreign subjects (90 eyes). The 1st group of myopic patients: 36 eyes with mild myopia (MSE-0.75D to-2.75D) and the second group is a control group: 54 eyes (MSE 0.50D to-0.50D)
MATERIALS AND METHODS
This was a prospective, comparative study of 80 foreign (90 eyes) healthy volunteers with different refractive status recruited from a population-based study from November 2016 to February 2017, All of the subjects underwent a comprehensive which included best-corrected visual acuity (BCVA); slit-lamp test; refraction measurement using auto refraction, Volunteers had no known eye diseases as determined by a complete ophthalmic examination. The study was performed in the ophthalmology outpatient department of Xiangya 2nd affiliated hospital of central south university.
Exclusion criteria included the following: (1) history of intraocular surgery or ocular injury; (2) having other ocular or systemic diseases such as glaucoma or diabetes mellitus which might affect the ocular circulation, (3) optic nerve diseases, (4) neurodegenerative diseases, (5) and advanced cataract or cloudy media opacity.
Eyes of each participant were assigned to one of the two groups according to refraction: 36 eyes with mild myopia (MSE-0.75D to-2.75D) and the second group is a control group: 54 eyes (MSE 0.50D to-0.50D).
All participants were interviewed regarding their medical history, and underwent an ophthalmic examination, included measurement of BCVA, refractive status using an auto refractometer (Auto Keratorefractometer KR-8800; Topcon, Tokyo, Japan), AL using an IOL Master (Carl Zeiss Inc, Jena, Germany), slip-lamp biomicroscopy examination, RNFL and OCT angiography scans were obtained by using AngioVue OCTA.
OCT Acquisition and Processing:
Optical coherence tomography angiography scans were obtained using a spectral-domain (SD) system (RTVue-XR Avanti; Optovue, Fremont, CA, USA). This system has an Ascan rate of 70 kHz with a light source centered at a wavelength of 840 nm and a bandwidth of 45 nm. Both eyes were assessed in each subject. Optic disc (6×6 mm) OCT angiography scans were acquired by two repeated B-scans at 304 raster positions, and each B-scan consisted of 304 A-scans. Two volumetric raster scans were taken consecutively, with one in the horizontal priority (x-fast) and one in the vertical priority (y-fast). Motion artifacts were removed by three-dimensional (3D) orthogonal registration and by merging the pair of scans. En face retinal angiograms were created by projecting the flow signal internal to the retinal pigment epithelium. All of these procedures were achieved using the RTVue-XR Avanti software. And if a scan contains severe artefacts, it will be excluded from the analysis.