Concussed Tipuric 'briefly lost sight' - Shane Williams
Justin Tipuric told Shane Williams he "briefly lost his sight" after the flanker was concussed playing for Wales against Italy in the 2016 Six Nations.
In his column in The Rugby Paper former Wales and Ospreys wing Williams said he spoke to the Ospreys flanker, 26, "a week after" the incident in March.
"He said he briefly lost his sight at the hospital, which is just frightening," wrote Williams.
Tipuric missed the rest of last season and Wales' June tour to New Zealand.
The 2013 British and Irish Lion suffered a heavy blow to the head as he fell from a line-out in Wales' 67-14 Six Nations win.
Ospreys and the Welsh Rugby Union both declined to comment.
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Williams referred to Tipuric's experience while backing his former regional and international team-mate to be a regular in the Wales line-up.
Tipuric has returned to training ahead of the 2016-17 season.
Williams wrote: "He was probably the most skilful forward I ever played with.
"Wales talk about expanding their game and doing what New Zealand and Australia do between forwards and backs.
"Tipuric is the ideal man to do exactly that."
Dr Barry O'Driscoll, a former medical advisor to World Rugby, says he is alarmed by Williams' comments about Tipuric's concussion.
"It doesn't surprise me and it does scare me," he said.
"It's very common in concussion that on the field straightaway you get stars and you get visual disturbance. You're much, much less likely to get loss of vision, but maybe afterwards you can.
"It's significant that he was off for a significant length of time.
"We're stabbing in the dark to a greater extent about concussion because we are not quite sure exactly what the consequences in the medium to long term are going to be.
"We don't know exactly what to look out for as far as warning players that this may cause you trouble in the future.
"We know so little about it that the more we're getting to know about it, the more worrying in a way it is because there's no good news coming out about it."