There are ema with the character 'め' (eye) and a mirror image of 'め' for the prevention of eye disease, and ema with the character '心' (heart) with a lock for the prevention of extramarital affairs.
眼病予防に「め」および左右逆の「め」を書いた絵馬や、夫の浮気防止に「心」の字に鍵をかけた絵を描いた絵馬もある。