High Minus PAL Design: Clarity VS....

I have a patient that is roughly -11.00 spherical equivalent. I put her in a Hoya IDLS Clarity, and she likes it OK, but still notices peripheral distortion at distance, although a similar amount to her old PAL (mystery lens). I am thinking about switching her PAL, but not sure if anything would actually be better. Auto III? Something else?

Quote:

---

Originally Posted by cowboytelemark

I have a patient that is roughly -11.00 spherical equivalent. I put her in a Hoya IDLS Clarity, and she likes it OK, but still notices peripheral distortion at distance, although a similar amount to her old PAL (mystery lens). I am thinking about switching her PAL, but not sure if anything would actually be better. Auto III? Something else?

---

The blur is primarily from unwanted astigmatism in the PAL design, and chromatic aberration due to the lens material. Use a PAL with a generous distance zone, and if you used 1.67, consider 1.70 or 1.60, with a nod towards the latter for its significantly higher Abbe value.

https://www.2020mag.com/article/chro...of-the-rainbow

Hope this helps,

Robert Martellaro

Thanks Robert. The Clarity DOES have a generous distance- or so say Hoya and most of my myopic patients. Trying a Seiko Surmount in 1.74 per lab recommendation- will let you know how she does.

Quote:

---

Originally Posted by cowboytelemark

Thanks Robert. The Clarity DOES have a generous distance- or so say Hoya and most of my myopic patients. Trying a Seiko Surmount in 1.74 per lab recommendation- will let you know how she does.

---

The blur due to chromatic aberration will be similar when comparing 1.74 (Abbe 33) and 1.67 (Abbe 32).

I doubt that the Surmount will have less distance periphery astigmatism than the Clarity, and that it's unlikely that the lab would know.

Best regards,

Robert Martellaro

Under the best of circumstances, a -11.00 lens is going to have a certain amount of peripheral distortion. Try any and all of the above, but manage expectations as well.

Quote:

---

Originally Posted by AngeHamm

Under the best of circumstances, a -11.00 lens is going to have a certain amount of peripheral distortion. Try any and all of the above, but manage expectations as well.

---

Absolutely but they probably didn't become -11.00 over night either :bounce: I'm going to guess this isn't their first rodeo.

In a situation like the OP stated I would look at EVERYTHING different between the two pairs first before thinking about PAL design. Size of lens, PD, Vertex distance (This is often a major factor I have found, POW compensation can mitigate this but if a frame sits further than an older one and has a bigger lens? big time) also Panto and face form wrap.

There are so many PAL designs out there now with little to no peripheral blur IMHO,I don't know the Clarity but if I was to use Seiko I would use one of their more T shaped designs than the Surmount for a high minus complaining of peripheral blur.

I know cowboy knows what they are doing fit wise so I'll be interested to hear what the final result of the change is.

Quote:

---

Originally Posted by Tallboy

In a situation like the OP stated I would look at EVERYTHING different between the two pairs first before thinking about PAL design. Size of lens, PD, Vertex distance (This is often a major factor I have found, POW compensation can mitigate this but if a frame sits further than an older one and has a bigger lens? big time) also Panto and face form wrap.

---

Agreed. Done. The lens size is slightly larger which is likely a contributing factor, but pt likes the frame and it is pretty small at 46 eye. Vertex distance is reduced as much as possible.

Have you dispensed the Surmount yet? I am having this exact quandary with a 1st time PAL; high minus and high cyl, with a +1.00 ADD :spin:

This wouldn't be an issue if I could get Hoya EX3 on an Auto III 1.74....

And why the surmount and not the superior? out of curiosity