How to control image size with gross anisometropia

[Lauren123]

I am a qualified DO but I am prepping for some additional exams and have come across some notes which I can't get my head around!

Vertically in the lens the powers are RE: -3.00 x 100 and LE: -1.00 X 80

Can anyone explain to me in layman terms how a px with 2.00 base down differential prism in the RE as above would get on with the following:

A Franklin split in the LE with the 2.00 base down in the segment only and a e-line bifocal in the RE?

Why would the prism be put into the L lens when the differential prism is in the RE? And is an E-line segment used as there is no jump?

I understand that with a slab off bifocal you would slab off 2 base down in the RE because you slab off the most minus lens but that has got me confused especially as it is only theory and I don't have any experience in dispensing franklin split lenses to understand how they work to control differential prism caused by gross anisometropia?

Any info would be great!

Thanks in advance!

[Crickett13]

A conventional slab off is base up not base down so there would be 2 base up in the eye with the most minus/least plus. A reverse slab off is base down and goes on the eye with the least minus/most plus, So yes you would put base down in the left eye on a Franklin segment.

http://www.opticaltraining.com/html/...e_sixteen.html

[PRECISIONLAB]

Consider the following with regards to Franklin / E-Line prism in Segment portion is base up as in other types of bifocals but with the MRP and PRP being the same. In traditional ST segments a reading height must be factored in (usually 10mm). With Franklin this is 0 and with power difference of 2 diopters requiring 2 diopters prism base down to negate or balance base up affect from add power in E-Line segment.