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scleral contact lenses, conjunctiva, lens flexure
PURPOSE: This article aims to report a new clinical finding associated with the wear of scleral lenses.
METHODS: Non-contact lens wearer subjects were recruited and fitted with large diameter (18 mm) scleral lenses. Lens was randomly filled with non preserved saline or non preserved carboxymethylcellulose-based artificial tears (Refresh Celluvisc, Allergan, Ca). The sinking of the lens on the nasal and temporal sclera was assessed periodically during a total of 6h00 of wear, with the use of anterior segment coherence tomography (OCT- Optovue, Clarion Technologies, Texas). Images were taken every 30 minutes for the first 2h00, then at 4h00 and 6h00 post-insertion.
RESULTS: The nasal side sinks significantly more than the temporal side by 23.0±7.3 μm (F(1,12)=10.043; p=0.008; 95%CI:[7.2 ,38.9]). This difference is significant with time (F=8.757; p<0.001) and there is a side effect (F=10.043; p=0.008). The type of solution does not influence the lens behavior (F=0.250; p=0.626). A new clinical finding was revealed during scan analysis. Conjunctival tissue displacement was seen, under the reverse curve of the scleral lens, shortly after insertion. This conjunctival “inlapse” (CI) was sustained over all the wearing hours. On the nasal quadrant, CI was reduced in height and present in only 8/15 subjects while, in the temporal quadrant, 100% of subjects showed an average CI of 38.39 ± 10.43 μm (t(84)=3.68; p=0.0072; 95%CI[17.64, 59.13]) 30 minutes post insertion followed by a non-significant decrease of 1.97 ± 10.34 μm (t(84)=0.19; p=1.00; 95%CI[-22.52,18.58]) between 30 minutes and 6 hours of wear.
CONCLUSION: Nasal sinking is more pronounced as compared with temporal lens sinking. This may explain the occurrence of a new clinical phenomenon identified to happen shortly after lens insertion, under the reverse curve of a scleral lens. In fact, CI happens mostly on the temporal quadrant, where more space is available for the conjunctival tissue to move. This finding suggests that conjunctival tissue reacts to scleral lens wear, not only in the inferior quadrant, where conjunctival prolapse is known to occur, but in every other one as well.
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