1. Don’t fear the cyl
Modern toric lenses work really well and so don’t hesitate to try them in low astigmats. Historically many of us were taught to undercorrect cyls in toric lenses but if the lens fits well, we shouldn’t be afraid to shoot for the moon. Anyone with a -0.75DC or above should certainly try a toric and often this group will have been ignored in the past by other practitioners. Don’t forget there are some patients with a -0.50DC cyl and high visual demand who can sometimes benefit for slightly over-correcting the cyl with a -0.75DC.
2. Don’t be too hasty
Ask yourself if this patient really needs a toric? Despite what we just said above, some patients with quite sizable cyls prefer spherical correction in contact lenses. Sometimes it’s the variability in the vision they can’t put up with or sometimes it’s that uncorrected cyl in presbyopes which provides a lot of help with near vision. Remember, the goal of lens fitting is to give the patient the vision they need for their lifestyle and not always achieve 6/4 R&L so you can pat yourself on the back for a job well done.
3. Know your torics
Different designs are really different – prism ballast, double slab-off, dual thin zones, etc. There is a lot of technical complexity in toric lens designs and the same powered lens in a different design can give a wildly different fit, vision and comfort levels. There is usually more variation moving between toric designs than you see moving between spheres. Rather than trying every toric under the sun at random, get to understand two or three designs that use different stabilisation methods so you can try a more targeted approach to troubleshooting visual variability or fit issues.
4. Trial banks are worth having
Being able to try a lens in practice is really useful not least because patients are often astounded that you have a lens in stock for their ‘very complex prescription’ rather than needing to order it in. Obviously the various power combinations are legion but having a complete set of axes and cyl variations is most important. You can dramatically cut down on the sphere powers you stock as it’s easier to top up with spherical over refraction in the consulting room than cyls or axes.
5. If nothing makes sense, revisit the baselines
Make sure you start fitting with a bang-up-to-date glasses prescription and keratometry… yes keratometry. We all know the significant limitations of keratometry but at the very least it can show you if the astigmatism is corneal or not, which is useful to know before you make a hash of things. If you get in a fankle with poor vision or bizarre over fractions that do not add up, repeat your glasses prescription. Relying on a prescription from months and months ago can lead to all sorts of problems later on.
6. Don’t forget the exotic options
Hybrids, rigid gas permeables, corneoslcerals and multifocal torics are better than they have ever been and with modern technologies and manufacturer assistance they are easier to fit than ever too. Do not be afraid to experiment with some of these more exotic options if you cannot get the vision and stability you need in simple designs.
7. Beware of being the fifth opinion
A new patient turns up and says four different optometrists have failed to fit them with soft torics despite what looks like a fairly simple prescription. Buyer beware! This is the type of patient who chews up chair time and complains of blurred vision with 6/4 acuity R&L. By all means try your best to help but make sure you know what you are getting yourself into and that you will be compensated properly for all the chair time sure to be required.
Ian Cameron is an independent therapeutic optometrist based in Edinburgh