Scared to administer glaucoma drops

I have a 12-14 year old (we think) cat that has glaucoma in one eye. We were given dorzolamide HCL/timolol drops to administer 2x daily but here are my concerns- he has a history of very very mild asthma, which is something that can be triggered by the beta blocker timolol in the eye drop. In addition to that, he had a heart murmur (allegedly) at one appointment that was never heard again. I’m nervous about the systemic effects of the timolol in his system through administration of the drops. Has anyone had any experience with using these in cats? I’m wondering if enucleation may be beneficial in his case since he already has such a low quality of life with me giving these drops. He is semi feral and doesn’t like me touching him on the good day. He hides from me for 2 days after I clip his nails and have to give gabapentin before I even attempt to touch him, so all of these concerns are aside from the fact that I don’t know if I am even going to be able to consistently administer them. I’m wondering if it’s bad for me to consider enucleation instead of daily drops to better maintain quality of life.