Many of the patients I see in community eye care practice are older people. I find it difficult sometimes to decide when I have found the optimum prescription during subjective refraction. Do you have any tips?

Some people find it difficult to make the choices we ask them to make during subjective refraction.

 We ask them if things are clear with lens 1 or lens 2. We ask them if things are darker with lenses 1 or 2 and sometimes ask about lenses 3 and 4.

It is my experience that if there has been a significant prescription change and we are far from the endpoint then patients can tell the difference between the clarity provided by each lens choice. Patients typically give quick, sharp, and definitive responses.

 When there is only a small lens change or we are near the end point then it becomes more difficult for patients to tell the difference between the clarity simply because we are near the end point and the differences in clarity are very slight.

 One technique I use when working on the spherical component is to put the current prescription in the trial frame and then with the patient looking at the smallest set of letters they can see on the sight test chart introduce a +0.25 DS and ask if the letters look just as clear with the lens or if they look clearer without the lens and then I remove it. People seem to be able to tell me if the letters are just as clear with the lens or are clearer when the lens is removed. It may be necessary to repeat this with a -0.25 DS lens although with older people (especially if they are not driving) I will try and find the most plus power I can. This helps increase the efficacy of the reading prescription.

 If I am working on the cylindrical correction I ask if my target (Usually a cluster of small black dots on a white background) is dark with lens 1 or 2 or about the same. This seems to work well.

 Give clear, short instructions, take your time, and be prepared to repeat the lens presentations. If the patient changes from a quick responder to a slow responder it’s probably because you are at the endpoint.


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