prism on single vision ?

[rkjr2222]

Help , a patient came in with sv r= -1.00 , L= -4.00 -1.00 x 80 . the doc wrote slab off grind but did not indicate any diopters. I haven't done one on sv , only ft and progs. Any advice ? Also does it still go on the higher minus ? left eye ? Thanks

[Lensman11]

You should contact the prescriber to see what he or she had in mind. Slab off can be done in SV lenses but if the patient is able to alter the gaze point on the lenses slab off won’t be needed. If they have a special situation where they have to look thru the upper or lower part of the lenses then shift the o.c. Up or down accommodate the situation.

[waynegilpin]

You should contact the prescriber ...........

Possibly just omitted the bifocal add?

[PRECISIONLAB]

Single Slab Off is a solution for those with limited motion an unable to maintain gaze through the OC's typically looking below lens centers for near tasks.

As with FT-28 Slab Off reading depth or location of gaze below single vision OC's must be measured in order to calculate vertical prism. For easy calculations assume 10 mm creating approximately 3 diopters of imbalance. Typically via free form machine processing the least minus eye is selected as base down prism is required.

[mervinek]

Possibly just omitted the bifocal add?

I would agree... this would be the most likely situation since SV slab is more rare

[waynegilpin]

I would agree... this would be the most likely situation since SV slab is more rare

"When you hear hoofbeats. Think horses, not zebras."

[Robert Martellaro]

Help , a patient came in with sv r= -1.00 , L= -4.00 -1.00 x 80 . the doc wrote slab off grind but did not indicate any diopters. I haven't done one on sv , only ft and progs. Any advice ? Also does it still go on the higher minus ? left eye ? Thanks

Most minus if custom slab. Get a freeform generated and a traditionally surfaced slab sample before you choose- the freeform is less noticeable appearence-wise, but has a wide blur zone, whereas the traditionally surfaced slab has a sharp junction zone.

"When you hear hoofbeats. Think horses, not zebras."

Right, unless if you live in Africa. See Occam's razor.

Best regards,

Robert Martellaro

[lensmanmd]

SV slabs are rare. Typically for sports, think cyclists, or therapeutics.
The prescriber, IMO, is relying on your expertise, as he/she isn’t.
Slab value for SV is dependent not only on RX, but down gaze. Unlike multifocals, the “10mm” rule does not apply.
Making matters worse is determining where to place the slab. On center? Pupil height? Then measuring down gaze to calculate the prism value.
Fresnels are the best option to trial before ordering the final pair.

Contacting the prescriber would be wise before starting on this journey. It will save you a lot of headaches and $$$