Recode the first fixation after target using loop

I am a freshman to Matlab and recently need to use it to do some data analysis. I have an eeg.event strcuture with one of fileds called 'type', I need to recode the first fixation (L_fixation) after stimulus onset ('111'). See the screenshot below.

Here is my code:

ix_nonrep=find(ismember({EEG.event.type},'111'));

for i=1: length(ix_nonrep)

while ~ismember({EEG.event.type}, 'L_fixation')

ix_nonrep(i)= ix_nonrep(i)+1;

[ffix]=ix_nonrep(i,:)

end

end

But I can't make it work as I what I hoped. I want to the loop can return the index, so I can use the index to rename the events. Does anyone know how to make it work? Thank you in advance.