Interesting/Mystery Case... ?

[AndyOptom]

So recently I was asked for assistance by a junior optometrist colleague, a pleasant young chap who's been keen to shadow my work habits, including converting normal PAL into office progressives.

After reviewing the case and interacting with the patient directly, I must admit, I was also rather stumped. So as follows are the case details etc.

Patient Rx:
RE +2.00 DS (6/6-)
LE +2.00 DS (6/6-)
Add +2.25 (N6+ @ 40cm)
Current pair of lenses, 1.50 Varilux Comfort Max Crizal Sapphire, regular corridor

Patient has recently started using a desktop monitor (at eye level) for work instead of just a laptop (which used to be in a downgaze position), and while generally very happy with her Comfort Max lenses, noticed the usual ergonomic challenges of using a desktop monitor.

My junior colleague proceeded to fit a pair of Varilux Liberty 1.50 to be used as office progressives as follows, with the Rx determined using trial framing:

RE +2.75 DS
LE +2.75 DS
Add +1.50
1.50 Varilux Liberty Crizal Sapphire, short corridor

Choice of Varilux Liberty was made as generally for converting PAL into office lenses, we stick to the same manufacturer of the main pair of lenses to hopefully ease patient adaptation using similar technology etc. why convert a PAL, I believe that topics has been discussed extensively here over the years, and we so far have a solid track record doing so.

So, patient claims that the desktop view is excellent with the converted PAL, but that she has zero near vision. In fact, she was wondering if she had been accidentally given SV lenses for her intermediate Rx. Laser engravings, lens meter measurements, and manual neutralise checks using trial lenses show that the converted PAL are indeed the Varilux Liberty as ordered. However, she still could not see close up using the lower half of the lens whatsoever, it was all blur. Sending the lenses back to the lab for reconfirmation revealed no detectable defects.

By the way, she is a regular patient along with her family, and has never been problematic.

We solved the case by just refitting her into a pair of what used to be called Hoya Tact (one of my favourite dedicated office lenses, and I believe I'm the last in the practice to consistently fit it), and I altered the ordered Rx as required to obtain the preferred indoor Rx. She remarked that the intermediate view was no longer quite as perfect, that the new pair of office lenses while satisfactory, was more sensitive to eye movement (understandably, Tact is sort of one oversized corridor running through the entire vertical of the lens). Patient has gone home happy enough, and we're working out a deal with the lab for hopefully a discount on the mystery unusable Varilux Liberty lenses (yes, boss is old school, we eat remake costs).

So... What are we missing here ��

[Uilleann]

You fit a traditional PAL and hoped it would work just like a computer lens. But of course, it isn't. Therein lies 100% of the issue.

Use the right tool for the job, and watch your expensive dispensing remakes drop to next to nothing. *shrug*

[Robert Martellaro]

Current pair of lenses, 1.50 Varilux Comfort Max

The +1.50 is the old add? Distance the same? Might just be that the wearer became used to a longer work distance at near and the stronger add is blurring that distance.

I saw a lot of folks with improperly low fit trifocals that would perform all close tasks through the intermediate segment, reading at 50cm to 60cm. The near segment was too low to be unusable. In many cases I would switch back to a bifocal with a cut add to match their preferred work distance.

Best regards,

Robert Martellaro

[AndyOptom]

The +1.50 is the old add? Distance the same? Might just be that the wearer became used to a longer work distance at near and the stronger add is blurring that distance.

I saw a lot of folks with improperly low fit trifocals that would perform all close tasks through the intermediate segment, reading at 50cm to 60cm. The near segment was too low to be unusable. In many cases I would switch back to a bifocal with a cut add to match their preferred work distance.

Best regards,

Robert Martellaro

Apologies if it wasn't clear:

The current pair of lenses is a pair of index 1.50 Comfort Max, regular corridor, that we dispensed a few months back.

Rx is OU +2.00 distance, Add +2.25. No complaints save for the ergonomics of a desktop monitor at eye level.

Converted PAL Rx was OU +2.75, Add 1.50. Lenses used were a pair of index 1.50 Varilux Liberty, short corridor. Great intermediate vision, zero near vision.

The longer working distance at near you mentioned might make sense since the converted PAL was a short corridor. The pair of Tact used that solved the near vision issue had a longer corridor after all, so this makes sense (although as mentioned, the patient felt the Tact had somewhat compromised intermediate vision compared to the converted Liberty).

You fit a traditional PAL and hoped it would work just like a computer lens. But of course, it isn't. Therein lies 100% of the issue.

Use the right tool for the job, and watch your expensive dispensing remakes drop to next to nothing. *shrug*

Given how the Rx was converted manually based on a trial framed working distance, we have a good track record doing so, especially for desktop users. Even with most office designs, intermediate vision is often cited as being narrowed both vertically and horizontally compared to a converted PAL, traditional or not (even in this case, while the Hoya Tact solved the near issue, the intermediate view was notably reduced somewhat to the patient, compared to the PAL we converted).

Currently, in the 4 years I've been with this practice, this is literally the first such failed dispense I've seen. For context, considering I myself routinely fit and dispense at the very least 2 or 3 such pairs weekly and have never encountered such feedback (zero clear vision at near), it did make me stop and think for a bit. Common lenses used for this role include Varilux Liberty, Hoya Summit/Amplitude (if a flatter lens is preferred), or the Zeiss Light D. The choice of lens is generally matched to the patient's main pair of PAL, same manufacturer if possible.

If you're wondering why I went this route, it's my go-to for anyone using those oversized desktop monitors at eye level. Have yet to see an office lens user happy with the width of intermediate vision for those, compared to a converted PAL.

[Elvis Is Alive]

With oversized/dual monitor use cases, I've always had better results with a short distance NVF lens design such as IOT Endless Office 1.3M, Shamir Workspace, etc.

They have a wider intermediate FOV than longer vison range NVF lenses like Shamir Workspace, Endless Office 4M, etc., and certainly more than converted standard PAL.

These NVF lenses were designed for a reason. I'd recommend dispensing them for anyone wanting an intermediate/near solution.

[Prentice Pro 9000]

You fit a traditional PAL and hoped it would work just like a computer lens. But of course, it isn't. Therein lies 100% of the issue.

Use the right tool for the job, and watch your expensive dispensing remakes drop to next to nothing. *shrug*

I've always had more luck with traditional PALs for office instead of the computer PALs. I started using them because I had a lot of patients with three monitors side by side. I use the shortest corridor and throw the computer Rx in there. It's essentially a bifocal at that point. I think with modern office PALs there's no clear explanation as to how the lens will be compensated or where the fitting height is (and yeah, I know you're supposed to know your product, but it's hard to find reps that know what they are talking about these days).

I would love love LOVE it, if a company came out with an office lens that addresses multiple lateral monitors.

[Kwill212]

I've always had more luck with traditional PALs for office instead of the computer PALs. I started using them because I had a lot of patients with three monitors side by side. I use the shortest corridor and throw the computer Rx in there. It's essentially a bifocal at that point. I think with modern office PALs there's no clear explanation as to how the lens will be compensated or where the fitting height is (and yeah, I know you're supposed to know your product, but it's hard to find reps that know what they are talking about these days).

I would love love LOVE it, if a company came out with an office lens that addresses multiple lateral monitors.

The IOT Endless Office series lenses are superb. I'd give them a try. Fit just like a normal PAL. 4 drop lens, fitting cross at pupil, order the full Rx. Success.

[Robert Martellaro]

The near point blur is due to power, position, or both. Strongly recommend standard corridors for task glasses, confirm that add power is not too strong, verify that the distance PD was used for the task glasses, check that the inset is not outset or crooked.

FWIW, I also use standard PALs for task glasses.

Hope this helps,

Robert Martellaro

[drk]

I don't like the idea, but I am using a lot of standard PALs for task, too. It's a cheaper option, sometimes. It gives a wide screen panorama. Use +0.50 for an "indoor PAL" effect or +1.00 for a "computer station" effect.

(If the cylinder is wacky, you may need to upgrade to an individualized for best effect.)

I don't fuss with the corridor, either, just to keep it smooth. I will fit dead center on pupil, though.

[optical24/7]

Big believer in conventional PAL’s over office designs for computer use (adjusted for distances used). Too many successes comparatively.

[Prentice Pro 9000]

Big believer in conventional PAL’s over office designs for computer use (adjusted for distances used). Too many successes comparatively.

I'm glad I'm not the only one.

[Prentice Pro 9000]

The IOT Endless Office series lenses are superb. I'd give them a try. Fit just like a normal PAL. 4 drop lens, fitting cross at pupil, order the full Rx. Success.

Thanks for the advice. I wish I had an IOT account. What do you think of their other lenses along with camber?

[AndyOptom]

(If the cylinder is wacky, you may need to upgrade to an individualized for best effect.)

I don't fuss with the corridor, either, just to keep it smooth. I will fit dead center on pupil, though.

Agreed on the general use of +0.50 or +1.00 over the distance Rx, its what most wearers seem to go for.

For higher cylinders, aniso/anti-metropia, prism, etc, then I tend to just order a dedicated office design and let the lab's Rx computer try to optimise for the exact Rx instead of a modified Rx.

Also agreed on fitting cross at pupil center, unless it's one of those designs where the corridor extends up past the fitting cross (in which case I sometimes fit higher or lower depending on the patient).