Presbyope with high refractive difference in R and L eye


Presbyopes who have a high refractive difference in both the right and left eyes and who present for the first time for an optical aid pose a real problem. My patient presented with an Rx of: right +4.75/ - 1.25 x 175, left +1.00/ - 1.25 x 180, add + 2.00.

The use of contact lenses and separate reading/distance optical lenses were ruled out because the convenience of one pair of lenses was the patient’s solution of choice.

Reverse slab off prism flat top 28 bifocal


Careful counsel along the way allowed this determined patient to grow into "wearing success". Using as little seg offset as possible, we worked out a reading distance with a trial frame where reading became comfortable. It was surprisingly more comfortable to read much more closely (than 50cm without accommodation for a +2.00) at 30 to 33 and this made for a satisfied patient.

A most embracing way to help assist fusion in anisometropic induced tendency to diplopia at near, is to use Younger Optics' slab off prism (flat top bifocal 28 segs). Younger kindly allowed us to trial a small (B I) left eye as well to soften the base down binocular difference, and it proved an aid to visual comfort.

Reverse Slab Off Prism Flat Top 28 Bifocal

Would you like to share a speciality lens case study with your peers? If so, please contact Craig Johnston - or 0476 834 342.

Jeff Greenwood, Optometrist

40 years' experience

Greenwood Optical, Brisbane.
Web: Greenwood Optical

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