"Review appointments for Glaucoma"

I have had 6 monthly appointments at the clinic since diagnosis of the condition and the medication was changed in Feb 2014. I am concerned that my due appointment appointment has been cancelled twice and no new date given. Appointments are no longer organised at the NGH Eye clinic and I have been advised that I will receive a letter giving me my next appointment. As it is now 9 months approx since my review and I have had no communication. Has the system changed to extend the review period or have I been overlooked. My sight seems OK at present and I regularly administer the eye drops but I would like an update on when I will next have a checkup