 I guess I'm the moderator. Good morning. My name's Eric Anderson. I'm a fourth year medical student. And I worked with Dr. Mosifar for the first two weeks. So I want to talk about what we worked on. And that's the regression of conductive caritoplasty in patients with or without refractive surgery. Just a brief overview, conductive caritoplasty or CK delivers radiofrequency energy, applied interest strongly to the periphery of the cornea. This causes shrinkage of the collagen and then steepening of the central cornea. Full circle of CK spots is applied. And it's a number of CK spots in the optical zone that it's delivered to that determines the degree of myopic shift. So for example, this is a treatment pattern for a single surgeon. It shows that you do eight spots, eight millimeters. You get about one diaphther myopic shift if you do eight spots, seven millimeters. You get 1.75 diaphthers of shift. Just a quick timeline of conductive caritoplasty. It shows that numerous methods have been used to change the shape of the cornea using thermal techniques. Started with a medical student, an 1898 Dutch medical student. He cauterized rabbit corneas. And he was able to induce one to three diaphthers of a sigmatism followed by corneal collagen research that showed that collagen shrank at 55 to 58 degrees Celsius. It's followed by Kauffman that used the Hedermetal Probe in 1975. And then Fedorov, a Russian physician, used hot needle caritoplasty or hot needle in the eye. And according to the research I found, the temperatures were up to 600 degrees Celsius. So well above what was needed. And then laser thermal caritoplasty in the 90s. This led to an uneven treatment effect. And then CK FDA approval in 2002. And the idea that CK uses inherent electrical conductivity of the cornea, this produces a more stable effect. HNK or hot needle caritoplasty was before in the US in 1988. They found a newspaper clipping I thought was pretty interesting. This is from 1988 in New Hampshire. And the Russian government said they're going to invest about $2.6 billion into 13 centers where patients were on a circle of conveyor may do hot needle caritoplasty. I don't think it ever came to fruition, but it was interesting. So FDA approved indications. Load of moderate hyperopes, 0.75 to 3.25 diaphthers of hyperopia. And then you need 0.75 diaphthers less for practice of sigmatism. This was the initial approval. And then it gained supplemental approval for presbyopia to induce modern vision correction, usually about 1.5 diaphthers of near vision. But it came apparent after approval that there was a regression effect. But there's only been a few studies of patients that had LASIK or PRK and that went on to CK. So we wanted to show that in those patients, the treatment effect of CK was more stable. So we picked out the mean refracted spherical equivalent. This was a standardized way to evaluate the regression and the few studies that I found. And then the best corrected visual acuity to measure the outcomes. Patients and methods, a retrospective chart review of 52 patients, 18 at sufficient follow up, six patients or seven eyes had CK after LASIK or PRK. Only one of those patients had PRK. And then 12 patients under 12 patients, 50 eyes were the controls. Patient demographics, average age was about 55. Follow up time, there was a big range. Controls were 17 months. And the CK after LASIK was 24 months. There was no significant difference between the baseline of the two groups. The preoperative refraction, just looking at the spherical equivalent, was about 0.8 in the controls and 0.27 in the CK after LASIK or PRK. The CK spots were also less in the LASIK patients, around 9.6. This was shown that the LASIK patients had a greater myopic shift. The initial studies like 2003, sometimes the myopic shift was exaggerated by like three or four factors. But eventually, with more experience, it became less. Usually around 0.5 factors. This is the postoperative refraction. If you look at the change from pre to post, a spherical equivalent, it looks like the control patients had a greater effect of 1.73 diopters compared to 1.4. So about a 0.3 diopter difference. However, when you control for the different treatment spots, and then we use a mixed effects linear regression, it shows that the LASIK patients actually had a greater response to treatment. And minus means a greater response. So we had a greater response across the board in the sphere of cylinder and refractive equivalent. It's not well studied, but we're thinking that the flap effects induce a decreased coronal elasticity, and this creates a greater steeping effect. So some subchanges in the posterior, interior or mellar. We also looked at safety, defined as a loss of two or more lines at six months. No patient had a loss of two or more lines, and they all had greater acuity of 20, 25. And usually no loss of lines. So start looking at the regression to a bunch of profile graphs. And it shows on average, there is a trend after about six months that you regress to your preoperative spherical equivalent. And these were the, each line is a profile patient at 20 months. These are basic patients at 30 months. It shows a similar regression to preoperative values. I did a profile graph of both of the groups together and it shows that no group lies above or below each other. So it doesn't look like from this graph that there's a difference between the groups. This is 50 months, and then 30 months. And then once I went through all the data, I just quickly put it onto a box chart and did a quick linear regression. I got pretty excited with the result so that there was a difference of elastic patients. Usually about .02 diopters compared to .36 in the controls. It was significant at .038 p-value. However, on second look at the data, we realized that because the visits, the follow-up visits per patient are independent. You can't do linear regression. So we had to take it a step farther. And we did multi-level regression analysis. And this showed that time sensor surgery is highly significant, but there wasn't a difference between the two groups. So both of the groups had a regression of spherical equivalent of .03 diopters. And on average, at any given month, the LASIK patients had a spherical equivalent of .38 diopters lower, but this wasn't significant. And we thought that this was just a difference in the baseline of the spherical equivalent of like .5 diopters. So this shows us a graph of the regression analysis using the equation blow. Usually crosses the X-intercept at 25 months in the control patients and 34 months in the LASIK patients. That just gives you an idea of how it regresses over time from six to 30 months. So in conclusion, we found that the CK was safe and effective. No patient lost two or more lines of visual acuity. They all had 20, 25 or greater. The rate of regression was similar with .03 diopters, spherical equivalent per month. The LASIK patients did have a lower, on average spherical equivalent per month, but wasn't significant. But we did show that after controlling the number of spots, the LASIK patients did have a greater response, .42 diopters as spherical equivalent. Conclusion continued. Because of the safety profile, CK does remain an appealing option for certain patient populations. As more patients seek refractive correction after LASIK, and if they have a thin lamp or dry eyes or a flat cornea, CK will fit them well. It may also be a reasonable bridge for low hyperopes or early cataracts and maybe too early for a clear lens extraction. It also remains a bioblops for presbyopes who are tired by reading their glasses. Any questions? I know that was fast. Good. Dr. Olson. Yeah, we try to increase the power just by including everybody that we had outside of two months, but we're still. Because nobody is allowed. Thank you. We'll move on.