Although limitations in IOP lowering and potential of
non-IOP lowering,
neuroprotective strategies, have been discussed, I think IOP lowering have more
potential for the preservation of visual function in glaucoma, if
we take diurnal IOP in consideration.
Diurnal variation of IOP lowering effect of timolol and
latanoprost was
prospectively compared in 62 eyes of 31 normal tension glaucoma patients. After
four weeks wash-out of glaucoma medication, patients were randomly assigned to
treat either with 0.5% timolol twice daily or latanoprost once daily for three
months. Patients were instructed to measure their diurnal IOP every three hours
by using Home Tonometer (HT), a self-measuring air puff tonometer, on day 0
without medication, 1 day and 3 month after medication.
Timolol significantly lowered IOP at all the time measured
but for 6AM on day 1. After 3-month use of timolol, IOP lowering effect decreased
at each time measured especially in the morning and the night. On the contrary,
IOP lowering effect of latanoprost became significant 5 hours after the first
instillation and lasted for the rest of the day on day 1. After 3 month, the
effect of latanoprost increased, lasted for whole 24 hours, and did not have
diurnal variation. The pattern of the diurnal variation stayed the same as day
0. I think it is necessary to
maintain IOP control for the whole 24 hours period for proper glaucoma
management. CR:N