Hi everyone! It is my first post in this forum.
The question that has taken my sleep is about survival analysis.
I have to make a survival analysis plot. It is easy when one thinks of a final event, such as dead. It is complete, unquestionable, and irreversible.
However, I usually work in ophthalmology studies. Sometimes, I have to follow eyes concerning the intraocular pressure (IOP). Let's suppose I define the limit of IOP of 20 mmHg, and the failure is the pressure above this limit. Suppose I follow the IOP every week, for example, week 1 = 18, week 2 = 18, week 3 = 19, then week 4 = 23 mmHg. The patient reaches failure in week 4.
There is a more difficult condition: what if the patient has the IOP such as 18 / 18 / 23 / 15 / 21 / 25 / 16???
In this case, the patient reaches failure in the third observation, but in the next (15), he or she entered the normal range. Then, it comes to the failure criteria again, and finally, in the last observation (16), joined the normal range!!! How can I make a survival plot in this case? Is it possible to consider these "chunks" of time when it is in the normal range? I appreciate any help from you. Have a lovely weekend!