[Music] decide to fit a patient in a corneal or intra limbal lens design the ideal pattern that we're looking for is either slight apical pulling or three-point touch so three-point touch would be this photo right here where the lens basically touches in three different locations one spot in the middle two in the mid periphery and so the weight of that lens is just spread out on the eye and when you have a lens like this it creates four very distinct zones that you should try to describe in your actual fit in your actual chart so the first zone is the center portion so here we have light apical touch the next zone is your paracentral pulling so we have a nice ring of paracentral cooling then you have a mid peripheral bearing zone where the lens rests and then lastly you have your peripheral clearance so we need a nice little ring of peripheral clearance to make sure that sheer exchange is happening so that it's healthy so if i were to describe the fit on the left that little video i would say you know there's mild to moderate apical pulling there's paracentral pulling but i don't see any bubbles there which is good we have our ring of mid peripheral bearing as well and then in terms of peripheral clearance i would say it's a little excessive at six and a little minimal at three and nine but at least i don't see my tier meniscus breaking at six which i'll show you an example of in a little bit and so one thing we want to avoid definitely is any type of harsh touch on the cornea like this video on the right so here you can see that dark area where that lens just like to sit on that cone if we were to leave this patient alone like this sure enough they'd probably come back with spk and from the collect studies we know sdk will lead to scarring and down below you see how that tear meniscus just breaks when she blinks at six o'clock so there's a lot of excessive edge lift that's over there as well and so probably not the most comfortable lens for this patient now a lot of my students will come and say to me hey dr lee i see touch and then i'm like is it harsh or is it light and they won't really know how to tell the difference and so what my mentor dr edrington at scco taught me was you know to really differentiate between harsh touch and light touch is look at the border between the center portion of the lens and that paracentral pulling if that border is very distinct and easy for you to see then it's most likely a harsh touch as opposed to the picture on the right where the border is very fuzzy and hard to define because you know the tears are kind of just you know ebbing back and forth underneath that area of touch and so um this right here kind of for me is how i differentiate between the two harsh touch will definitely lead to sdk whereas like touch we're hoping will not so we have to monitor and make sure that it's healthy now a quick note about intra limbal gps in general these tend to be just a little bit bigger than your traditional corneal gp right 10 to 12 millimeters in diameter because they're larger they don't move as much on the eye and the edges of the lenses tend to be tucked underneath the eyelids and so patients feel that these are more comfortable and so what you kind of notice sometimes too is an improvement in stability better centration of the lenses um and so when i think about when i may switch from a corneal gp to intralimbo gp it's when my patients in gps are having all of these similar issues right comfort issue centration is and a lot of pattern can be really difficult to get this is a patient that i kept playing around with during residency trying to improve its fit he has areas of touch in some places he had a lot of cooling and others because his eye was just so irregular and i love this fit because it just looks like pac-man it's just what it reminds me of um and so what i have to learn too is that you know these patients don't have regular corneas so don't expect beautiful fluorescein patterns every time really what you're trying to do is maximize your patient's vision and not hurt the eye and so as long as you're not seeing spk and staining and all of these other you know issues with a poorly fitting lens and i said just continue with it if your patient does start to show ocular health issues then we really have to think about the next step in revision rehabilitation and so if you're going to fit your patient in a corneal or intra limbal design first and foremost you know follow the fit guide some guys tell you start with deep case some guys say start with average k really just get a lens onto the eye and then start making changes based off of the floor scene pattern you see and really you want to use your wrapping filter so look at the difference in the floor scene pattern between the photo on the left and the photos on the right the red filters really highlight that forcing pattern it makes it easier for you guys to see if there's pulling or touch and things like that and then once you find the lens that gives you you know really light touch or really slight pulling then go ahead and do an over refraction don't over refract the lens that's you know harshly touching the eye or has a lot of pulling because that over reflection is not going to be accurate okay and then lastly you're going to want to document the rest of the lens fit and then call your consultant and just kind of talk with them give them your over-refraction make changes you need to make to your peripheral curves or special coatings you may want to add on or if you wanted to know a specific material for your patient and that's generally how i go about fitting my corneal and intra limbal lenses one other diameter or one other parameter that i really like to modify as well is the optic zone so a lot of your cone patients they're going to have a lot of paracentral pulling because if you can imagine a lens sitting on top of a cone it's going to teeter-totter and then all around the base of the cone you're going to have a lot of liquid and fluid just filling up there and if you have too much paracentral pulling you can actually start to get bubbles there as well and it's not comfortable for your patient right and so this is a pain that i saw where all i did was i took the ocd and made it a little bit smaller and essentially dr bennett taught us this actually at our gpli residence day you're making the optic zone smaller to tuck that optic zone around that cone making it just a little bit more of a snug fit and so by doing that you get rid of a lot of the paracentral pulling and hopefully you get rid of the bubbles that may come with it as well so hopefully you guys can see the difference there [Music] you