I have some relatively extensive experience with eye surgeries, as I had PRK (a more "robust" alternative to the popular Lasik which doesn't create a potentially fragile "flap" so it's ideal for combat sports and military personnel), my wife had Lasik, my father cataracts, and a friend a surgery to the eye muscles following impact damage in kickboxing (likely similar to what Aspinall had).
Whilst the healing itself is fairly quick, from days to weeks depending on the procedures, you definitely cannot have any impacts or infection dangers (thus sweaty gloves etc) for a couple of months. So assuming these surgeries are successful and fully resolve his issues, he can recommence fight training in 2 months and therefore, at the earliest, fight in 4-5 months.
Additionally, because his specific issues have been caused by impact (poking), he will likely be highly protective of the eyes and need months to get comfortable with getting punched on them - even risk being poked, as it can indeed happen unfortunately - without being afraid of some renewed and more serious damage.
In general, whilst not career enders per se, these eye injuries can easily keep him away from fighting a whole year since they happened - autumn 25 to autumn 26 - and might have him return with a much greater fear of damage than he had previously, which obviously would be a psychological hindrance in the cage.
Overall a really unfortunate situation, going from being the new champ and the beginning of a new HW era, to an unclear return and a division in disarray for the foreseeable future.