We have this patient, male 65 years old that has been using for more than 4 years this prescription.
R -2.75 -1.50 x 170 3.0 prism base out 20/30
L -3.25 -1.00 x 180 4.0 prism base out. 20/40
Cr-39 Single vision lenses base 4.25.
He went to his ophthalmologist last week because he was having diplopia and he gave him this prescription.
R -3.00 -1.50 x 170 10.0 prism base out
L -3.00 -1.00 x 180 10.0 prism base out.
Note: Here there are no Opticians so we Optometrist sell and manufacture lenses too. In this case i am acting as an Optician in U.S. since the prescription came from a outside source and i only make the eye glasses as the prescription say.
I made the lenses on Poli base 3.25 (needed enought blank thickness) and mount then on the same frame he was using the old prescription. With new prescription he complains of blurred vision at far distance but the diplopia was not present.
I checked again the vision and the prescription of the old glasses and is the same i mentioned as olg glasses prescription.
One question i made myself was, How he can have so bad vision with a 0.25 change on prescription?
The patient did not have time this day i took him to the examine room and did a fast overrefraction while wearing the new glasses and found that a +.075 esf. gave the best vision and there was no diplopia. So according to this fast overrefraction the prescription should be
R -2.25 -1.50 x 170 10.0 prism base out
L -2.25 -1.00 x 180 10.0 prism base out
Then we reassembled the old glasses on the frame and i did was able to do a fast overrefraction while wearing the old lenses and found that on the right eye he does not accept changes so -2.75 -1.50 x 170 is the best prescription. On the left eye he has -3.25 -1.00 x 180 but accepted a +0.25 sometimes and a +0.50 others.
So according to the overrefraction made on the prescrption he has been using for more than 4 years, the prescription should be.
R -2.75 -1.50 x 170 10.0 prism base out
L -2.75 -1.00 x 180 10.0 prism base out
So same patient and i now have 2 different prescriptions.!!!!!!!!!
This morning, i placed one of the lenses that has 10.0 prism on a automatic lensometer and found that it has the prescription ok. see figure 1
The i raised up this lens to see if change in vertex distance had any efect and found that it does not as expected.
Then i lower the lens on the thickest end and found that the spherical power started to increase negatively -3.00,-3.25,-3.5,etc. Actually, when this lenses are on the frame and the patient is wearing them, the frame has a curvature that makes the thicker part of the lens closed to the face than the nasal side of the lens.
See picture 2.
So should i make him new lenses with
R -2.25 -1.50 x 170 10.0 prism base out
L -2.25 -1.00 x 180 10.0 prism base out
prescription because in this case they act as if they where
R -3.00 -1.50 x 170 10.0 prism base out
L -3.00 -1.00 x 180 10.0 prism base out.
I really need fresh ideas on this.
Help is welcome.
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