Advanced Fitting of Scleral Lenses

Transcription

1 Advanced Scleral Lens Fitting Advanced Fitting of Scleral Lenses Jason Jedlicka, OD, FAAO Indiana University Evalua?ng fit at follow up Evalua?ng landing zone Dealing with as?gma?sm in the over refrac?on Lens removal issues Tear exchange / Debris Dealing with conjunc?val landmarks Front surface wemng Conjunc?val prolapse Lens Evaluation at Follow Up Evaluating the Landing Zone for Toricity U?liza?on of toric landing curves is easy with most scleral designs Improves fit, comfort and makes the lens more stable and less likely to accumulate debris How do we determine if this is helpful or needed? Scleral Topography If you do not have scleral topography 1

2 Shadowing from the Lens Edge Easy way to assess the edges for excessive lir Posi?on slit beam across lens and view the far lens edge Direct illumina?on tells you if you have blanching or compression a?ght fit Shadowing of Lens Edge Indirectly evalua?ng the lens edge allows you to see edge lir easier a loose or flat fit Shadowing of Lens Edge 2

3 Toric hap?c OCT Evaluation of Lens Edges Possible Consequences of Using a Toric Haptic Managing this wi?h a toric hap?c will work, but will likely shir the lens slightly toward the side with edge lir Loss of central vault if you are flaxening a meridian that is currently too?ght Make sure to compensate if your current vault is marginal at all Bubble forma?on at applica?on if not inserted close to the proper axis Altering the posi?oning of a front toric if the toric hap?c is added later How Much Toricity Should I Add? If you are doing a lot of sclerals, it is a good idea to consider having some toric diagnos?c lenses Consulta?on can help If unsure, some will be bexer than nothing, you can always reorder Typically most people tend to underes?mate the amount needed, so don t skimp on the toricity How Much Toricity Should I Add? Communicate to lab your findings With experience and familiarity with a design you will learn how to es?mate how much is needed If you can measure it, communicate that to your lab Don t be afraid to add toricity! Visser ES, Visser, R, van Lier HJ, OXen HM. Eye Contact Lens Jan;33(1):21-5. Modern scleral lenses part II: pa0ent sa0sfac0on. The interview showed differences in comfort, visual quality, and overall sa8sfac8on in favor of the back- surface toric designs compared to the back- surface spherical designs. 3

4 Managing residual astigmatism Flexure When a scleral lens fit looks good, but visual acuity is reduced, a spherocylindrical over refrac?on should be obtained If correc?ng as?gma?sm improves vision, the reason for the as?gma?sm should be determined Lens Flexure vs. Internal As?gma?sm To differen?ate, over topography is useful RX: x 180 Topo demonstrates 1.75 D residual cylinder Resolving Flexure If flexure is present: May try to increase lens thickness to resist flexing Also consider toric landing zones if demonstrate that there is edge lir in the steep meridian Resolving Flexure If the flexure appears to correlate to the shape of the eye: Consider fimng a toric landing zone If arer fimng a toric landing zone, there is s?ll residual as?gma?sm, then a front toric can be added to resolve the remaining cylinder Residual Astigmatism without Jlexure If there is no scleral toricity to stabilize the lens design, then the stability must be added to the front surface These lenses can be fixed assuming no rota?on unless observed in clinical semng Con: Adds thickness and bulk to the lens 4

5 Residual Astigmatism without Jlexure In many cases, there is enough scleral toricity to use toric landing curves to stabilize the lens rota?onally Residual Astigmatism without Jlexure Need to compensate for lens rota?on if there is any (actual or an?cipated) LARS rule applies Lens marking is typically on flat meridian Lens Removal What causes a scleral lens to be difficult to remove? It is suc?oned on due to: Edges too?ght (easy to visualize typically) Excessive vault / inadequate landing zone width There is too much axrac?on between the lens and the eye due to: Lens too closely aligned to the eye (too lixle vault over too much surface area) Excessive landing zone width Tear Exchange how much should we have? While tear exchange is generally a good thing, it can be a problem with sclerals Minimal tear exchange (but not none) is recommended Usually if you can easily push fluorescein under the lens manually, but none gets under the lens without manipula?on, you are about right Poor removal technique: pushing DMV onto the lens in the wrong spot or with too much force Not opening lids wide enough Remember, a well fixed scleral lens should come off easily Lens Removal If the lens does not allow tear exchange / allows very lixle tear exchange with manipula?on, it is likely going to suc?on to the eye and cause redness and difficulty with removal Lens Removal A lens that is too?ght and suc?oned to the eye is not going to allow any tear exchange and will create problems Typically will have issues with redness under the lens and difficulty with lens removal If the lens allows too much tear exchange, debris will accumulate under the lens and cause blurring of vision 5

6 Excess Tear Exchange / Debris Debris is a common problem that can impact vision Usually takes a few hours to get bothersome for most pa?ents Can be seen at slit lamp at follow up Debris Posterior lens fogging is due to debris accumula?on in tear reservoir Typically means excess movement /edge clearance in one region Debris is mucin and lipid, enters with blink but cannot get out ARer 2 minutes After 4 Minutes no manipulation ARer 4 minutes 6

7 Debris Debris will follow path of tear exchange / fluorescein when applied Most commonly channels under the lens superior / temporal, but can come from anywhere there is a loose fimng rela?onship Can be improved by steepening the landing zone in the meridian that the debris is migra?ng in from Debris Manage with notch, microvault, or EyePrint Pro Conjunctival Landmarks Some patients have abnormal conjunctival or scleral issues such as pinguecula or blebs Conjunctival Landmarks These can be dealt with several ways: Go smaller if feasible Go larger is shallow enough and close enough to the limbus Notch the lens Microvault Lens Notches Notch Size Needs to be wide enough to not constrict obstacle Form semi- sealed 8it with no movement Too deep or wide of a notch can cause bubbles Better with smaller diameter lenses Watch IOP in blebs carefully Lens Notches When Ordering Measure depth and width Pictures always help lab Consider keeping a notched trial in of8ice 7

8 Conjunctival Landmarks MicroVaults Microvault measurements Microvault: 3.0 mm wide Located at axis 175 Peak at lens edge 250 microns max eleva?on Microvault needs to be roughly 5 degrees inferior to the horizontal meridian or at axis 175 Lens with Microvault Impact is mainly on vision, not comfort 8

9 Evaluate and manage lid disease Monitor for changes to the Lid Wiper How does pumng a liquid reservoir over the corneal surface impact the feedback mechanism to the brain that governs basal tear produc?on? Remember that wearing a scleral lens increases the surface area of the ocular surface that is exposed Puts increased demand on the tear layer Many scleral wearers have ocular surface disease as part of their condi?on ARer 15 minutes in a scleral lens All of these reasons and more that scleral lens wearers need to be aggressively using lubricant drops several?mes a day over their lenses Consider punctal occlusion Plasma treatment Hydra- PEG? Using a drop of lubricant on a lens tool or a coxon?p applicator and rubbing the lens surface while on eye can also help when removing the lens is not prac?cal Adding condi?oner to the lens applicator at the?me of inser?on may also help with ini?al non- wemng issues Conjunctival Prolapse 9

10 Conjunctival Prolapse Benign? Managing Prolapse? Questions? Many claim there is no reason to try to resolve it Conjunc?va can become adhered to limbus over?me and create vasculariza?on Reduce limbal clearance if possible, move to quadrant specific design if and when available, or monitor 10