The College of Optometrists

Can anyone help me with the management of the following patient?

I had a patient complaining of headaches and eyestrain and had never had glasses. On examination they had poor vision in one eye, with a refraction of +4.00 (6/6)and practically emmetropic (6/5) the other eye. They did not appear to be suppressing with the prescription in place.

Could the patient tolerate such a large anisometropic prescription when they have never had correction before?

Thanks

Its a shame you don't give the patients age and also the available accomodation.

I guess this is a case of accomodative infacility. There is a great article on this very subject available on the Optometry Today web site - look up the articles that were published Jan 07.

It is quite interesting that they don't have any amblyopia in the +4 eye. However, the art of prescribing is to explain to the px what you are doing and why and then prescribe enough to help with the symptoms - and no more.

THey would find a large anisometropic prescription very hard to cope with because

- they would get unequal magnification in each eye - causing tilting of the visual field and the horopter = the floor would tilt away from them and the walls would bow.

- The unequal prismatic effects means that they would have to move their head about when gazing - or suffer prismatic strains.

- The +4 lens would cause unequal near points when accomodatiing - one eye would see closer that the other eye when looking near.

The trick in Rxing would be to try to give the good eye some thing - even its +0.25 - then give something to the 'bad' eye to aid the strain. You could 'push' the good eye - by using a +5ds over the bad eye to oclude that and concentrate on the good eye with plus lenses as a binocular refraction. If you do - then don't forget to check each eye's final vision with a flick of your ocluder (thats to stop you getting carried away with your bino refraction).

Check which eye is doing the looking by using a -2ds placed infront of ach eye when px is actively looking and noting over which eye is the greatest effect. Typical power in the bad eye would be +1.75 or so. More or less depending on any binocular strains mesured with a fixation disparity unit.

So many optometrists would offer as a first Rx +0.25 +1.75

and review if the px found that it did not help.

You would also advise they adapt carefully for safety before driving and stairs and to only wear the glasses during times when their eye strain used to occur (perhaps at work).

You would warn them that glasses would awake their binocular functions and this may well cause odd eye pains, headaches and feeling of disorientation = but this will pass with adaption.

You could also offer contact lenses as an alternative if their anterior ocular health permitted.

Hope it gives you some ideas

=steve