update blog copytext from WRP

contents/articles/2017-01_retina-mapping/index.md

@@ -2,23 +2,25 @@
 title: Retinotopic to Spatiotopic Mapping in Blind Patients Implanted with Retinal Prosthesis
 date: Mon Jan 30 2017 10:36:53 GMT+0700 (ICT) 
 author: Pupil Dev Team 
-subtitle: "Blind patients implanted with a retinal prosthesis fitted to a modified Pupil headset to measure the accuracy in mapping stimulated retinal signals to the world coordinates..."
+subtitle: "Pupil eye tracking tools used in conjunction with retinal prothesis measure the accuracy in mapping simulated retinal signals to world coordinates..."
 featured_img: "../../../../media/images/blog/epiretinal-array-dark.png"
 featured_img_thumb: "../../../../media/images/blog/thumb/epiretinal-array.png" 
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 <div align="center">
 	<img src="../../../../media/images/blog/thumb/epiretinal-array.png" class='Feature-image u-padBottom--1' alt="Epiretinal Array of Electrodes" style="width: 50%;">
-	<div class="small u-padBottom--3">Image Source: [Retinotopic to Spatiotopic mapping in blind patients implated with the Argus II retinal prosthesis](http://iovs.arvojournals.org/article.aspx?articleid=2597840#149774812)
+	<div class="small u-padBottom--3">Image Source: ["Fundus image of the epiretinal array of 60 electrodes implanted in a patient's eye."](http://iovs.arvojournals.org/article.aspx?articleid=2597840#149774812)
 	</div>
 </div>
 
-The observation that electrical stimulation of retina in blind patients can create visual percept led to the development of retinal prosthesis devices implanted in blind patients. For the percept to be useful, the electrical stimulation should convey information to the brain with the correct spatial coordinates.
+Current retinal implant systems (like the Argus II) use images from a scene in order to create electrical stimulations on a patient's retina. These systems have been shown to be helpful for blind people in accomplishing activities of daily living. However, current systems have a narrow field of view (18 degrees x 11 degrees) which require the participant to move their head in order to scan a scene. Integrating eye tracking will enable patients with retinal implants to use more natural eye movements to scan the scene.
 
-In their paper [Retinotopic to Spatiotopic mapping in blind patients implated with the Argus II retinal prosthesis](http://iovs.arvojournals.org/article.aspx?articleid=2597840#149774812), Avi Caspi et al., researched blind patients implanted with a retinal prosthesis fitted to a modified [Pupil headset](https://pupil-labs.com/store/) to measure the accuracy in mapping stimulated retinal signals to the world coordinates. And to demonstrate that an eye tracker can be calibrated on the patient based on the retinal prosthesis.
+Avi Caspi et al., demonstrate that, "the brain accurately maps the artificial vision induced by a retinal prothesis based on instantaneous gaze position" and that "remapping based on eye position is feasible and will increase visual stability in prosthetic vision." The researchers combined a modified Pupil headset with the Argus II system in order to develop calibration procedures for the implanted blind patients and measured accuracy in mapping simulated retinal signals to real-world coordinates.
 
-In the experiment, the patient's gaze positions were recorded with timestamps synched to the onset of the stimulation using [Pupil eye tracker](https://pupil-labs.com/store/), and by indicating the location of the percepts using a handheld marker recorded with the scene camera. 
+When using Pupil, for example, a sighted individual typically looks at a marker that can be detected by the world camera to calibrate. However, "with blind subjects, calibration of eye tracking is not a trivial matter." The researchers developed a calibration procedure by activating specific clusters of electrodes in the retinal implant. For each cluster activated, the researchers then asked the participants to hold a red ball at arm's length and align the red ball with the location of the "light". The red ball was used as a marker that could be tracked in the space of the world camera. The researchers then know the position of the pupil, the location of the stimulus on the retina, and the position of the marker within the world camera space. With these known coordinates the researchers are able to solve a system of equations to establish a 2d mapping from pupil coordinates to gaze coordinates.
 
-The results from the study have shown that the brain has the required signals to process stimulated retinal coordinates based on the crucial step in measuring the position of the eyes relative to the orbit to build a correct representaion of the spatial coordinates accurately. 
+The results from the study have shown that the brain has the required signals to process stimulated retinal coordinates based on the crucial step in measuring the position of the eyes relative to the orbit to build a correct representaion of the spatial coordinates accurately.
+
+Check out the their full research paper [here](http://iovs.arvojournals.org/article.aspx?articleid=2597840#149774812).
 
 If you use Pupil in your research and have published work, please send us a note. We would love to include your work here on the blog and in a list of [work that cites Pupil](https://docs.google.com/spreadsheets/d/1ZD6HDbjzrtRNB4VB0b7GFMaXVGKZYeI0zBOBEEPwvBI/).