 We'll go ahead and get started. We have one of our awesome retina fellows here today. Initially, all I saw on the title was LASIK. And I was wondering, why is she talking about LASIK? But then when you read the whole title, she's going to be talking to us today about posterior segment complications of LASIK. Sounds like a very interesting topic. I'll go ahead and turn the time over to Julia. I thought you were going to say there are no posterior segment complications of LASIK. And we can all go home. All right, so as everybody knows, LASIK is the most common procedure with the treatment of refractive errors in the world. And it's obviously very safe and efficacious. And there may be some people in the audience who have had LASIK surgery for a correction of refractive error. And the most commonly reported LASIK complications that we hear about and talk about are related to the refractive outcome. Overcorrections, undercorrections, as well as corneal and anterior segment injury and wound healing. But there actually are some posterior segment complications of LASIK. They're very, very rare. And they're rarely reported because they're usually managed by a different set of doctors than the people who perform the LASIK surgery in the first place. But the main reason that it's difficult to talk about posterior segment complications of LASIK is because it's hard to establish a cause and effect relationship in individual cases. In other words, if you hear about a myopic patient undergoing LASIK who developed a retinal detachment a month later, it's hard to say that the retinal detachment was caused by the LASIK procedure. Or what you can say is that there's a suggestive temporal relationship. And there's no standardized approach in the literature or in our discussion of this to say what is the time window that we attribute things to LASIK or even consider a suggestive timeframe. For example, if somebody develops a macular hole eight months after having LASIK surgery, does that have anything to do with a LASIK or they're just developing a macular hole? And even if there's a suggestive temporal relationship, something happening a few days after, there's still no conclusive proof that the LASIK surgery was the cause. So why is the retina fellow thinking about this at all? Well, I got to thinking about it because I saw this patient. This was a 30-year-old woman who had mild myopia and she underwent an uneventful LASIK procedure. And I saw her in the retina clinic about two weeks later and she was complaining about intolerable distortion and shadows in her left eye. And these are the color and funnest photographs of the back of both her eyes. Unfortunately, this photograph doesn't really do justice to what the exam was, but I'll kind of tell you what I saw. The right eye, she was 2020 in both eyes. The right eye had a completely normal fundus, good foveal reflex, no changes in the pigmentation whatsoever. The left eye, and it's kind of hard to see because the macular itself looked completely normal and there was a good foveal reflex, but kind of overlying the macula and over the fovea, there were several little circular globs right in the vitreous of what looked like blood that was resolving. And you can see them on OCT, you can see them kind of casting a shadow over the retina and you catch them here in the hyeloid and they're casting a shadow on her retina. The problem is because she was a 30-year-old woman, she had a very formed hyeloid, so these things were sitting right over her fovea and not really budging and kind of really interfering with her vision and that's kind of what they look like through these little circles. And you can see some suggestion that maybe the hyeloid had separated here just kind of focally over the area of the fovea. So I guess the first question is, why would lacyc affect the posterior segment at all? Why should there be any effect? And I guess the intuitive thought is there's some sort of mechanical stress on the eye when we're doing lacyc surgery. In order to create a corneal flap by a microcarotone, a suction ring has to be applied to the globe and so an intuitive thought is that the axial length of the eye is gonna change when that happens and that can cause traction on the macula and the vitreous base and create breaks in the retina. So this is something that's actually been looked at and studied whether or not the axial length in fact changes in lacyc surgery and there are two recent cadaver eye studies and one in vivo study all using A-scan ultrasound to measure axial lengths. And the two cadaver studies actually had conflicting results. There was a study of six pig eyes that showed that the globe shortened during application of the suction ring for the microcarotone and in eight human and nucleated eyes they showed that the globe lengthened. The in vivo study looked at axial lengths before and after application of the suction ring in 21 eyes and they found no significant changes in axial length. What they did notice is that the lens thickness decreased in 18 patients, so about 86% of the eyes and their hypothesis was that shrinkage of the lens diameter may cause a power vector especially in young myopes where the anterior hyaloid is adherent to the posterior lens and that can create some sort of tractional force causing tears or macular holes and in less formed vitreous cavities contraction of the lens may cause a PVD of posterior vitreous detachment. Other things that have been looked at to try to explain why Lacyc may cause posterior segment complication is complications is cutting time. It's believed and I got the sense from reviewing the literature that longer suction times may be associated with a higher risk of posterior segment complications but there's not really definitive data to show that. But interestingly posterior segment complications like optic neuropathy were reported in the early days of Lacyc when suction times were longer than they are now and there really have not been any recent case reports of that happening. The other interesting phenomenon is that the number of published posterior segment complications has not increased proportionally to the increase of the number of total Lacyc procedures which makes you wonder are we using better micro care tomes or shorter suction times. Another more new development ventosecond laser to create the flap is that better? It obviously ventosecond laser allows a non-mechanical creation of the corneal flap but you still need a suction ring to stabilize the eye. There is less vacuum with the ventosecond laser technique it's about 30 to 40 millimeters mercury as compared to 60 with a conventional micro care tom but longer times are required to create the flap. And interestingly there's a case report from 2005 from UCLA of a macular hemorrhage after ventosecond assisted Lacyc. What about the laser treatment itself? All posterior segment complications of Lacyc have been reported either with primary procedures or with enhancements that involve recutting of the flap so always using the micro care tomes. There are no reports of vitro retinal complications just with lifting a flap. However interestingly there are two reports one of retinal tears and one of a detachment after PRK where obviously no suction ring is applied at all. So and again this is not a cause and effect this is kind of a temporal thing somebody had PRK and then the head of detachment can't say the PRK cause of detachment but it's a temporal relationship that's being reported in the literature. So what are these posterior segment complications that I'm talking about? Posture vitreous detachment, regmetogenous retinal detachment, corneal vascularization and macular hemorrhages, macular holes and system macular edema and then more rarely optic nerve disease, visual field defects, vascular events like cordial infarctions and really just rare case reports of uvella fusions, central cirrus, coritinopathy, cordial infarctions like I said and toxoplasmosis reactivation. So there's a couple of interesting studies about developing PVDs after Lacyc surgery. There's a study from Argentina that looked at B-scan ultrasound before and after Lacyc and 50, I mean 100 eyes of 50 patients who underwent myopic Lacyc and if the patients already had a PVD they were excluded from the study so these were all people who did not have a PVD preoperatively and interestingly 4% or two eyes in the low myopic group so less than minus four refractive error and 24% or 12 eyes in the high myopic group which is greater than minus seven developed PVDs by ultrasound post Lacyc. Subjectively, 8% of the patients in the low myopic group and 32% in the high myopic group reported symptomatic floaters after Lacyc and in another study similar percentages 95 myopic eyes up to minus eight, 38 refractive error nine developed a partial PVD after Lacyc so sort of same percentages. Very metogenous RD. So again, keeping in mind it's kind of hard to attribute the detachment to the surgery but it's still interesting to kind of look back and see the incidence rates of this and Dr. Aravalo does a lot of work on this in Venezuela and he did a retrospective review of over 38,000 consecutive eyes that underwent myopic Lacyc and their refractive error range was minus 75 to minus 29 which I think is kind of surprising I guess in Venezuela they do Lacyc for minus 29. The mean was minus six and 0.08% so 33 eyes of 27 patients developed retinal detachments but the range was 12 days to 16 months post-op with a mean of 16 months. The mean preoperative refractive error in eyes that did develop a detachment was about minus eight, 75. The outcomes of surgery to repair magnetogenous detachment in these patients was that a best corrected visual cutie of 24 year better was obtained in 38% of the eyes and 2200 or worse in 22% and that's mainly because of preoperative vituratnopathy or delayed referral to a vituratnol specialist. So again, temporal not causal relationship between Lacyc and magnetogenous retinal detachment and interestingly the overall yearly incidence of retinal detachment in myopic eyes up to minus 475 is published in the literature as 0.015% and then high myopes greater than minus 10 is 0.075 per year. So this is actually a lower incidence rate than just the overall rate of retinal detachment in the high myopic over minus 10. Another interesting study that I came across appropriately entitled Importance of Fundoscoping Refractive Surgery published in the Journal of Refractive Surgery in 2007 looked at 4,800 consecutive Lacyc patients in a practice I think in Denmark over three years undergoing Lacyc and they reported the good thing about the studies that they actually had sort of a more standardized examination of the patients pre and post Lacyc and they reported 52 patients who had posterior segment pathology that required intervention. 45 of these were detected preoperatively. So there were only seven cases post-op and they had reliable fundoscopic examinations of these patients preop. So they knew that they had normal retinas before and the pathology was observed between 10 and 60 months follow up and only two of the patients came in with symptoms of flashes and floaters. None of these seven cases actually had a detachment. They all had either tears or holes in lattice that were treated. So the incidence of retinal detachment they reported was 0.03 per year in the myopic candidates and there were no cases of detachment after the refractive procedure. So, and again, that's a lower incidence rate than even in the low myopes. Another interesting, this is kind of an aside. There's a paper about refractive surgery after sclerobuckling for retinal detachment. And I always wondered about that. Does it work? Is it good? Is it safe? I mean, it's a small study. It's only 10 patients, but these are people who had one or more previous retina reattachment surgeries and they all had a sclerobuckle. That was one of the inclusion criteria for the study. And I think five of them had LASIK and four had PRK and they were followed for an average of 67 plus minus 14 months. So everybody was attached at that follow up period. Nobody had a retachment or a new tear or new retinal pathology. The problem was that only six patients landed within a diopter of their intended correction, seven within two, and then one patient was plus 225 over, one was minus 250 and one was minus three. So the refractive outcome was very disappointing, I think. So it may be safe, redetachment-wise, but the refractive outcome, at least in this study, was disappointing. And then from the standpoint of retinal surgery on patients who have had LASIK, we always worry about the flap, flap dislocation. And it is a risk of vitriol retinal surgery on LASIK patients, especially if the epithelium has to be degraded, the cornea is becoming edematous. You can lose the flap completely or just by manipulating the epithelium, displace it so that you get interface particles, stream the flap, epithelial ingrow. If the flap is displaced or disturbed during surgery, the recommendation is to, you know, obviously irrigate the interface, if it's been lifted, replace it in place of planal contact lens over it and send the patient to their anterior segment doctor immediately. There's actually some authors in the advocate using a contact lens over the cornea and using a sutured lens in 20-gauge or 25-gauge cases, but that's not routinely done. The recommendations overall for LASIK patients who are gonna have retinal surgery is to avoid epithelial debreatment if at all possible. Knowing the location of the hinge before surgery is very helpful, even just knowing it just in case, because then you can direct your epithelial scrape. If the location of the hinge is unknown, the recommendation is to start nasally and advance temporally, because that's usually where it is and your risks of displacing it are the least and using a non-contact wide-angle viewing system like the biome instead of irrigating contact lenses. So going back to the posterior segment complications, coradonia vascularization and macular hemorrhage. It's kind of disappointing literature on this. Obviously, high myopia can be associated with breaks in Brooks membrane and coradonia vascular membranes unrelated to having a LASIK procedure. And macular hemorrhages and lacrocracks have been reported after LASIK. There was a study of 2,955 consecutive LASIK treatments, and in that study, three eyes developed new coradonia vascularization, 0.1%, but the interval, again, was four to 26 months and that incidence rate was not different than in their practice just for myopic patients developing CMVMs. So it seems like having LASIK didn't really affect that incidence rate. There was a case report of a unilateral valsalval-like retinopathy with subhyloid intra-retinal and sub-retinal hemorrhage 15 hours after bilateral hyperopic LASIK. Macular hole, again, Aravallo did a big retrospective study to look at the incidence of macular holes and he found it to be 0.02 in a population of over 83,000 myopic eyes. The holes occurred within the first six post-operative months in 60% of the patients and 18 of the 19 patients were female. The outcome of macular hole repair in this patient was very similar to idiopathic macular holes. There is hole closure and improvement in visual acuity in 92.8% of the cases. Interestingly, in a Chinese cohort of almost 2,000 consecutive surgeries that were followed for a year, there were no macular holes observed at all. Optic nerve diseases and visual field defects, like I mentioned, these are just case reports and there's a case report of a 28-year-old female who had a unilateral visual field defect that persisted a year after bilateral LASIK and a 39-year-old man with bilateral optic neuropathy who had visual field defects in both eyes after LASIK. But there have not been any reports since 2001, which is being attributed to better instrumentation and shorter suction times. Additional adverse effects, UVL fusion syndrome has been described in three eyes of two patients for hyperopic LASIK, not surprisingly. There has been a case report of bilateral cordial infarctions in a 23-year-old woman who had hyperopic LASIK and there have been two reports of reactivation of oculotoxoplasmosis after LASIK, one five days and one 52 days post-op and that may be related to topical steroid use after the surgery. Central serous, there have been three case reports to date in the literature regarding central serous following LASIK. One patient was myopic and had symptoms a month after LASIK. One patient had unilateral hyperopic LASIK and had symptoms five weeks after and one patient had bilateral high hyperopic LASIK, really high, plus five and plus seven and had symptoms four days after the procedure but on further review of his history, it sounded like he may have actually had a history of central serous before having the refractive procedure and there have been no cases reported of central serous in the literature in PRK patients. The reason that I'm harping on CSCR is that we actually did a study about CSCR looking a retrospective study of CSCR patients over the past five years and we found some interesting observations regarding refractive surgery that I want to share with you so we looked at all patients at the Marin Eye Center who have been treated for central serous and we identified about 250 patients, eight of which had a previous history of refractive surgery, five had LASIK and two had PRK and none of these patients had any documented oral or inhaled steroid use. Several of them reported high stress jobs. One was a TV producer and one was an engineer and several of them reported being type A personalities for whatever that's worth. So here's the table of results and obviously this is a retrospective chart review so it has the limitations of that. So for example, for patient five, he was seen for central serous in Ratna but we did not have good information about actually when he had his LASIK, what his refractive error was and how long before we saw him. So but what I'd like to point out that's interesting here is that the two PRK patients actually develop symptoms one a month after and one 19 days after their surgery and they're both myopes. Everybody else, I don't really think this is, it's hard to say that it's related to the LASIK, I mean, nine years out. So again, it's difficult to establish a cause and effect relationship and obviously central serous is a multifactorial disease but it's possible that the longer use of topical steroids after PRK may be a risk factor and this may be why the two PRK patients actually had symptoms at least within a suggestive time window after their surgery. So what's the bottom line? What am I trying to say? Refractive surgery is very safe from the posterior segment perspective and it's possible that increased suction times with the microcaretome are associated with a higher rate of posterior segment complications but that is not proven. The key is dilated fundus examinations prior to refractive surgery are important. There should be a retina evaluation for any areas of suspicious lattice, atrophic peripheral holes and a careful macular examination for pathology like myopic related changes, lacrocracks, pigmentation changes that may suggest old central serous and of course there has to be a discussion with a patient regarding the need for followup based on the preoperative refractive status. In other words, the risks of being a myope don't disappear after surgical correction of refractive error. Well, there's really no guidelines specifically, especially yes. I mean, I think it helps just like Dr. Bernstein was saying for them to see a retina person and to have that discussion about the possible risks. I think when it comes from a vitro retinal surgeon, it maybe has more of an impact. I mean, obviously you don't have to as long as you document that you've seen it and you've discussed with a patient that that may predispose them to a retinal detachment. The thing is we really don't know if the LASIK procedure itself is an independent risk factor for the patient with that atrophic hole for developing a detachment. We don't have an answer for that. So that may be something that you need to discuss and document that you discussed. I mean, the other thing is in these studies that I was mentioning about detachment, they kind of glom together all the detachments that they saw afterwards. But for example, one of the cases was a young myope who was like minus 15 OU who developed bilateral retinal detachments 12 days after LASIK. So again, can I tell you that that's what caused it? No, but that's a pretty suggestive thing when somebody walks in 12 days after high myope with bilateral detachments as opposed to somebody who 60 months later, developed a unilateral vocal detachment. Maybe that myope would have had it anyway. Right, many patients retrospectively, the number of detachments was so low that it's not really powered enough to look age group by age group.