 have been sated will switch gears to the front of the eye. So completely different topic, it's far away from retina and research as we can get. So I'm going to share a few different cases that I think will be of interest to anyone doing cataract surgery. Patient one, and I'll try to keep this interactive. So I'm going to pick on certain residents. So no offense to anyone. Patient number one, 64-year-old, 3 plus NS in the right eye, uncorrected vision 2100, refraction is given. So we do the topography. Let's see, Russell, how would you interpret this topography? That's a crab claw, Peter. What does that signify? Excellent. So this patient did indeed have polisid marginal degeneration. And Russell's referring to this crab claw appearance of skewed deviation of the zones of astigmatism. So you have patients with PMD and cataract. Now Russell noted he picked out the astigmatism of 5.6 generated by the computer. But if you look closer at the central zone, actually there's about 7.3 diopters of astigmatism essentially. And the reason I point that out is in these complex eyes, the astigmatism given by the topographers often. And so it is valuable to take a step and look at the central zone. If you average these numbers, you get about 7.3 diopters of cylinder. So what I planned to do was insert a T9 lens, should correct about 4.4.1 diopters of cylinder, and do AK incisions, astigmatic caratotomy incisions at a 380 micron depth at a 7 millimeter optical zone. And by my nomogram, that should correct about 2.3 diopters. I did not want to be too aggressive on the AKs at a 7 millimeter optical zone, because if you do too much, you can destabilize the cornea, especially in a patient with PMD. So conceptually what we did was take this cornea, inserted the lens along this axis, did AK incisions at the maximal areas of astigmatism. And that resulted in an uncorrected visual acuity of 2040 with a best correction of 2025, very close to our target. So 7.3 diopters take away 4.1 with the toric, take away another 2.3, is left with about one and a half, as you'd expect. Now, could I have done more AK? Sure, but that would have risked some destabilization of the cornea, so I chose not to. Number two, in question with RK, about 20 years ago, 8-cut RK, got a cataract in the right eye, best correction with refraction was 2100. Brian, how would you interpret this topography? Oh, sorry, Brian Zog. Sorry, Brian, I did see you, but I'm afraid to Zog. I can't even say Brian Arx Foundation, both of Arx. Yeah, that probably doesn't matter so much. So again, the computer tricked you. So 0.6 diopters of cylinder on this computer reading and everything just looks blue centrally from the RK flattening. Now, one thing to bear in mind here is that everything looks blue, but the scale only starts at 30 and a half. So if you get this kind of picture, ask your tech to lower the scale. Because when you look centrally, you see there's actually, it's not just all flat. 32 diopters, 31 diopters vertically, 36 or 37 more obliquely. So there's actually a lot of stuff going on in the central cornea that's not visible by just looking at that central tilt. And so paying attention to the scale relative to what's going on is key. And very often the computer just sees something, the tech prints it out, no one takes a moment to look at the scale. And you think there's only 0.6 diopters of cylinder when there's a lot more. No, the computer would still say 0.6, but you would have a color cue that would say, hey, I need to take a look at this more. Yeah, I'm a master is measuring the central, three, three and a half millimeters. It's measuring at 12 points. The Lens Star measures at 21 points. The Lens Star measures out to 4.5 millimeters as well. In the post refractive surgery cornea, the IOL master is essentially useless for keratometry reading. It's great for axial length, but it's essentially useless for keratometry reading. And for that matter, the topography doesn't, you can't go off the topo numbers either by themselves. Okay, so, talk about the central cornea. Now, if you plug all this into the IOL, Ascrus Calculator for post-RK patients, it recommends doing a IOL power of 23.5. Okay, now remember that number, 23.5 is what the Ascrus Calculator recommends. PenaCAM, we have. PenaCAM measures the posterior cornea. It's very helpful in these post-refractive corneas. And this is a typical PentaCAM printout. And for refractive surgery for Lasik and PRK, you're gonna pay attention to the front. You're gonna pay attention to the thickness map and the posterior cornea. But that's not actually what we need here. We need what's called the EKR report. Again, you have to ask your tech to go print the EKR report. And here, what you find of use is the following. First, look at the central K given by the PentaCAM and the K is given at the one in two millimeter zones. And if you average all of these numbers, that I find, the zero, one in two millimeter zones in the PentaCAM, that I find gives a very nice estimate of keratometry in a post-RK or post-Lexic eye. And then the next thing you wanna piece is the astigmatism, about six diapters at a two millimeter zone, about four and a half diapters at a three millimeter zone. And averaging the cylinder at two and three millimeters gives you a very good sense of what astigmatism you need to treat. Again, on these post-RK and post-Lexic eyes. And when you average the zero, one in two zones and plug that into the IOL master, 31.61 millimeters, axiolength of 26.92, given by the IOL master, we get a predicted using master KT formula of 24.5 millimeters, 24.5 diapters, as opposed to if you adjust use the IOL master numbers. Okay, do you see that? The IOL master gives a much higher reading than what we plugged in from the PentaCAM. So if we had gone with the IOL master readings, we would have inserted a 20 or a 20 and a half diapter lens. Let's see, first to your resident. Is Russell down the line? Ah, Brian, sorry. Keep forgetting you, you're at a table. So Brian, if we had inserted a 20 diapter rather than the 24.5, what would have happened to the refractive error? So patient would be left excellent, right? So that would have resulted in a hyperopic surprise. That's my prediction. And as it turned out, we inserted a T9 lens to treat that about five diapters of cylinder that we observed in the PentaCAM. And with the 24.5, we achieved very close to our target. Okay, as opposed to the IOL Ascrus calculator, which recommended a 23 and a half, we would have been left with probably a plus one of spherical equilibrium. Or the IOL master by itself, which would have resulted in a plus five, most likely. That makes sense. Let's see. He had a pretty bad cataract, about two and a quarter. So he wasn't a very good refractor for optropatia. Number three, 67 year old lot of cylinder on the manifest, pretty dense cataract. Dan, what do you see on this topo? Big red blob, excellent. Look at these numbers for a second, 56 and 48. Do those mean anything to you? Those high caratometry readings? Right, does that point you to any particular diagnosis? Right, and so if you look at the central K, inferiorly is actually 62.9 versus the superiors of 59. So that's 3.9 more inferiorly than superiorly. So does that prove caratoconus? But it's highly suggestive. It's highly suggestive of caratoconus, and he did have caratoconus, and you can look at the rings on the caratoscope, and you can see very steep axis pointing this way. If you probe it with the pentacan, you get a much nicer look at what's going on in the central cornea, inferior zone of steepening. And again, if you do that same exercise of averaging the central zone, zero, one, two, you get a much different number than what's on the IOL master. And so this was a complex case, caratocon with cataract, and so I looked at the caratometries every which way until Sunday, central topography, pentacan, zero, one, two, EKR report, and when you have all of these numbers not really hanging very closely together, I just tend to throw out things I don't like if I don't like the scan, or I average things. And in this particular case, I averaged it, I got a mean of 54.08, the cylinder, the topo and the pentacan disagreed substantially. So here, you have no choice but to sit down with the patient and have a really earnest conversation that part of this is shooting darts in a dark room. And you have to set that expectation that we're gonna give it our best effort, but ultimately we can't predict refractive perfection. And the patient was very good about it. Put in a T9 lens. I did do some LRIs on this caratoconic patient and put the T9 along that axis to the LRIs here and here. Not too aggressive with the LRIs, even though he's 67 and is probably cross-linked from life, didn't want to be too aggressive with the LRIs in the caratocone. An outcome was pretty good. You know, he was happy, he actually wanted some gear. Just two more cases, got about 15 minutes. Cemetery old status most lacy, about 15, 16 years ago. Mild cataract, you already know he's a high expectation person because he's had his Lasik in the early days. Topo shows this nice central blue zone for a classic of Lasik. Panicam numbers, 31.2 centrally, are quite different than what the Topo predicts. And so running through that same exercise, averaging the zero, one, and two millimeter zones for predicting the central caratometry and then averaging the cylinder at two and three millimeters which results in about one and a half doctors of cylinder. Plugging that into the IOL master. This is from the Panicam zero, one, two, that's the axial length, predicted 22, technus lens. This actually correlates very nicely with what the Oscars calculator predicted, 0.75, that we hit the nail on the head. Now for the astigmatism, I treated AK at a seven millimeter optical zone. Reason being he has a Lasik flap. So I don't work as well in a patient with Lasik because it's beyond doing a limborelexing ascension is beyond the optical zone created by the flap. So I do AKs in that context at a seven millimeter zone within the flap. Certainly do need to know the corneal thickness there. Know what depth to go to. Last case, 62 year old at transplants for keratoconus 30 years ago. Had a cataract done seven years ago in the right eye, left eye, four years ago. Their spherical equivalent was very good. What's the spherical equivalent in the left eye? Try again. Good. So minus 3.5 plus half of six, minus 3.5 plus three, minus a half, circle of the root there. Tret, what's the spherical equivalent on the right eye? So they did a good job with their cataract lens insertion because he was left with circle of the root plus 0.37 in the right eye and minus a half on the left eye. This is what the topo shows. Now, 6.12 dieters of cylinder on the right eye, correlating pretty nicely with that refraction. If he had stitches, we would take the stitches out but all his stitches are out. This thickness map will be important. Just remember, he's got thicknesses of about 600, 700 in the mid peripheral cornea in the right eye. Now the left eye, he's got 9.16 dieters of cylinder. Why does he only have six dieters of a stick to his under refraction? Any gaseous trend. Got nine dieters of cylinder on the topo and the topo is a good topo. Okay, lens is not tilted. Postural cornea is a good guess. Check the pentakam. The pentakam says the same with trial lenses. This was done with trial lenses. Good, good thought. Any guesses, Dan? Leah? Jim? Any guesses? Not the postural cornea. Okay, so what happened about five, six years ago in the world of PCILLs? Indeed. So the lens that he had in the left eye, the lens that he had in his left eye, so he didn't have his lens card. We only saw that on dilation. So very important, always dilate your patient. So he had a T5 lens and a T5, Jim, how much is a T5, correct? Try again. T9 corrects 4.1. So a T5 corrects about two and a quarter, two and a half. So he had nine dieters of cylinder corrected two and a half dieters by the T5 lens that was inserted at the time. He was left with about six dieters of cylinder on his refraction. Okay, so now he comes. He's had his transplants, he's had his cataracts docked and used something for me. I can't wear my contacts anymore, wear glasses. Any recommendations? So, so LRIs would be outside the graft, AK, fair enough. So we did a new version of AK using the interlaced laser. So we have femtosecond laser already. Femtosecond laser that works very nicely and that we paid a lot of money for. Can do an interlaced AK based on this corneal thickness map. We did about 380 microns deep at seven millimeters on the left eye, on the right eye based on this corneal thickness map. We did about 580 microns deep with the interlaced laser. And that's the real value of the interlaced. With the step knives, with the diamond guarded blades, you have fixed depths. With the interlaced, you can really set your depth to whatever micrometer. And so, we did about three clock hour incisions on both eyes to treat the six dieters of cylinder. Seven millimeters. Got 20, 25, day one, we just did this last week. This is what they look like. Very clean, beautiful cuts, precisely done by the interlaced. I feel like I'm a good corneal surgeon but I'm not as good as this. The manual diamond blade just isn't cut as good as this. And you can see how that overlays very nicely with the astigmatic zones on the topo. So, from a series of cases, I hope you'll take away is that first, don't be afraid of these complex cases, the situations can be tackled in a logical manner. Diaspora's calculator is helpful, but not the final word. The central keratometry on the topo and the pentakam are both very valuable resources. Generating both astigmatic planning and keratometric calculation. In the context of RK, very important, figure out how big the optical zone is. Use midday readings. If you have, all right, what do I mean by that? Okay, Jim, what happens to RK patients over the course of decades? Do they become more myopic or hyperopic with time? Excellent, RK is a progressive surgery. They become more hyperopic over the course of years and decades. What's the trend? What happens to an RK patient over the course of an individual day? Do they become more myopic at the end of the day or hyperopic at the end of the day? It's the opposite of their decadal progression. And so, an RK patient, if you measure them at eight o'clock in the morning, they will be having a flatter cornea than if you measure them at six o'clock at night. So, in RK patients, ask what time do you wake up? What time do you go to sleep? And pick a time that they can come in in the middle of that day to get a good reading. Or you can tell them to come in the morning and at the end of the day and average that, but that's a little bit harder to do. Shoot for additional myopia because of that decadal progression of hyperopia. In the post-lasic PRK patients, a couple of points. Post-myopic lations have more prolate cornea, so you want to treat their spherical aberration more with the technus lens, which has the most negative spherical aberration because the myopic glacial patients have more positive spherical aberration. The reverse is true for hyperopic glacial patients. The hyperopic treatment induces negative spherical aberration, so use an older model lens, which has positive aberration to counteract it. And in these really strange corneas with PMD or keratoconus, I just like to get all the measurements and average them and have that conversation with the patient setting expectations. And then in the arsenal of astigmatic therapy, we have lots of different options that can be combined or used individually, depending on the situation. Toric lenses, which are useful even if the astigmatism is skewed, you don't need a perfect bow tie for a toric to be useful. Manual MRI, manual AK, and interlaced AK. All right, I think my time is up. What questions do you have? I know I've covered a lot of material today. Yeah, with RK patients, don't do anything for at least four or five months because they're gonna change and just hold their hand and let them know things are gonna keep getting better. So it does take a while for the post-RK cornea to stabilize. No, the one I showed was about three months out and he was pretty stable from that. Any other questions or thoughts? Brad, there's no real long-term data. I under-treat in PMD in Karateconas. I'm pretty aggressive in LASIK and RK with astigmatic correction. I pretty much treat close to what I would normally treat in a normal cornea. The older the patient, the more stable their cornea is probably going to be just because their cornea is probably cross-linked just from natural life. Those are my general rules of thumb. Thank you. Pollucent margin.