The New York Mets will reportedly be placing Tomas Nido on ther injured list with a vision issue, which has to be rare amongst catchers. It makes sense that if the catcher is struggling with his sight, it would greatly damage his game offensively and defensively. His offense has been far below the MLB level to start the season, so this is a logical explanation.
Assuming this isn't an innuendo from the Mets and he does have legitimate issues with his vision, it seems strange it is only now being noticed. Perhaps his vision simply got worse very suddenly and requires a correction.
Mike Puma of The New York Post was the first to report Tomas Nido would be missing some time via Twitter.

An MLB catcher with unadressed vision issues for what is supposed to be a championship caliber team sounds like the start of a joke. Instead, it is the reality of the early season New York Mets in 2023. They have already been through the ringer with injuries, heartbreaking losses, and suspensions. Manager Buck Showalter even got ejected for the first time in his Mets' tenure.
The start to the Mets season has been about as bad as it could have been. Fans are ready and willing to roast their team. Many have been calling for Tomas Nido's demotion, considering his putrid .118 batting average. His removal due to a rather unique reason has only added fuel to the fire.
Catchers who are able to generate consistent offense are exceptionally rare in modern baseball. Players like Adley Rutschman on the Baltimore Orioles are the exceptions, not the norm. Nido is primarily there to help get the best out of the pitching staff. While this vision issue may have presented some difficulties, he was still doing well in that regard.
The New York Mets cannot catch a break, and will be losing one of their top catchers for some time.
Tomas Nido's trip to the Injured List is a big loss for the New York Mets

Despite some fans being happy about Nido's bat being knocked out of the order, the team will miss him behind the plate. He has the trust and respect of that pitching staff, as well as good chemistry with them, including Max Scherzer. The importance of a good catcher-pitcher tandem often goes overlooked but is crucial in the modern game.
Tomas Nido will miss some time, but will hopefully be able to resolve this issue sooner rather than later.