Bill Harvey: Straight between the eyes
Author: Bill Harvey
I am currently working on the first article in a major series on dispensing, written by Peter Black, due to begin in next week’s issue.
One of the first things I learned in this job was to develop a reasonably thick skin. One of the earliest CET articles I was involved with (and this was when CET was not compulsory) was a discussion of pachymetry and how different corneal thicknesses influence the reading taken with tonometers. Possibly because there was a discussion included of why a single conversion factor was not likely to be established, the article received some negative feedback. This was from the ‘why should we know about this? – our job is to supply glasses and contact lenses’ or ‘we are not doctors’ school of thought.
Some weeks later, we ran a CET article on taking a PD. Not only did this result in the highest participation of any CET published by Optician in my time here, but resulted in a few letters accusing us of ‘dumbing down.’ Our dispensing series kicks off next week with a look at PD measurement.
Most readers will be aware that the prostaglandin analogue drugs used in the management of glaucoma and ocular hypertension have side effects that include increased pigmentation of the lashes and iris. Indeed, they are available illegally in the US for cosmetic purposes. I didn’t realise until this week that bilateral use of these drugs over a year results in a decrease in the PD. A study in this month’s American Journal of Ophthalmology has shown that Pas results in a loss of orbital fat volume which causes a gradual movement of each eyeball inferiorly and nasally. Indeed, 12 month’s use of bimatoprost was found to reduce PD by over 2mm – enough to cause prismatic problems for higher corrections.
PD is important – not dumbing down. It has taken me 18 years to say that.