At 18.5, the subject of the second sentence, Jesus, causes a few problems. Most MSS read απεκριθηϲαν αυτω ιν̅ τον ναζωραιον λεγει αυτοιϲ ο ιϲ̅ εγω ειμι ειϲτηκει δε. But P60, P66 (possibly) and 05 omit it, as do some versions. 03 transposes it, to read λεγει αυτοιϲ εγω ειμι ιϲ̅ (I think the Nestle apparatus is misleading here to treat it as an omission with P60 and 05 followed by an insertion). So instead of taking ιησους as the subject of λεγει, the text in 03 makes it part of the answer. Then we find an Old Latin MS, 3 (Vercellensis), which reads dixit illis ego sum ih̅s aute̅ stabat. This is a reading which seems to start with a Greek text like 03 and then puts Jesus in the next phrase, as part of the subject of ειστηκει. The interesting point is that it is further attestation for the reading in 03, which casts light on the question whether ο ιησους should be in the text. It would be fairly obvious to think that the text originally read απεκριθηϲαν αυτω ιν̅ τον ναζωραιον λεγει αυτοιϲ εγω ειμι ειϲτηκει δε, and that ο ιϲ̅ was added to make it clearer. But the situation may be more complicated. The fact that both 01 and 03 read ιησους without the article is possibly significant but needs exploring. P60 shows a general tendency to omit which weakens its support here. The case for an addition seems strong, but one will need to consider the idea that ιησους was originally present.
It is rather typical of the way textual variation is inconsistent that there is virtually no variation in the Greek in verse in the phrase απεκριθη Ιησους in verse 8.