Extended Dehydration of Corneal Allogenic Intrastromal Ring Segments to Facilitate Insertion: The Corneal Jerky Technique

Abstract

Purpose: The aim of this study was to describe a new technique to facilitate the insertion of corneal allogenic intrastromal ring segments. Methods: A single-segment corneal allogenic intrastromal ring segment (CAIRS) was trephined from donor corneas and allowed to markedly dehydrate for 75 minutes before the start of the procedure with a room humidity of 35% to 45%. The duration of the insertion step and the intrastromal segment size at 1 week as measured by optical coherence tomography were compared with previously performed single-segment CAIRS procedures using the conventional technique. Results: A total of 41 eyes of 36 patients underwent 1-segment CAIRS insertion of the same trephination size (750 µm). Fifteen eyes underwent the conventional insertion procedure, and 26 eyes had a dehydrated segment inserted. The time taken to insert the CAIRS analyzed by surgical video recording starting after the femtosecond tunnel creation and initiation of the insertion to the segment ironing step was 282 ± 103 and 97 ± 23 seconds for the conventional and the dehydrated segment technique, respectively (P < 0.001). Anterior segment optical coherence tomography performed 1 week postoperatively revealed similar segment thickness and width of 471.3 ± 54.1 μm and 1285.1 ± 191.0 μm for the conventional allogenic segments and 483.4 ± 58.3 μm and 1227.2 ± 165.2 μm for the dehydrated segments (P = 0.515 and 0.314, respectively). Conclusions: Markedly dehydrated corneal allogenic segments are easier and faster to insert than the nondehydrated ones while maintaining similar sizes intrastromally. This dehydration technique makes the procedure similar to the one with synthetic segments and hence reduces the learning curve.

Donut-shaped Corneal Allogeneic Intrastromal Segment as an Alternative to Deep Anterior Lamellar Keratoplasty in Advanced Keratoconus

“…Shady Awwad described the “jerky technique”, 20 where prolonged dehydration for 60 minutes in a room with 35% to 50% humidity results in a jerky-like stiffness to the CAIRS, thereby allowing it to be held by a pair of forceps and inserted into the tunnel, as an acrylic ICRS. We used this technique, and it seems to help the implantation significantly because the rehydration of transplanted tissue in contact with the host cornea makes it more difficult to progress inside the tunnel.…”

Bowman Layer Marking for Correct Placement of Corneal Allogeneic Intrastromal Ring Segments

“…It is therefore desirable to implant CAIRS with the thicker, firmer BL side facing centrally toward the corneal apex to maximize the flattening effect obtained. CAIRS may be inserted in the nondehydrated 1 or dehydrated 14,15 state. The nondehydrated state allows accurate sizing and customization to be translated onto the keratoconic cornea but has a slight learning curve for implantation, whereas the dehydrated state is easier to implant but has disadvantages such as taking more preparatory/ surgical time and slight shriveling of the tissue leading to difficulties in aligning against the marks placed on the patient's cornea.…”

“…Parker et al and Awwad et al also described dehydration of the CAIRS before implantation to facilitate insertion. 14,15 We suggest BL staining before implantation, whether implanting in the hydrated or dehydrated state, to allow easy and accurate implantation.…”

Customized corneal allogenic intrastromal ring segments (CAIRS) for keratoconus with decentered asymmetric cone

“…Corneal allogenic intrastromal ring segments (CAIRS)[ 1 ] was first performed in 2015, and as described by us, refers to the intracorneal placement of ring segments of allogenic tissue of any source such as fresh cut segments, unprocessed, processed, preserved, or packaged segments. [ 1 ] These are being performed with greater frequency[ 2 3 4 5 6 7 8 9 10 ] because of the refractive and topographic effects they provide similar to but with greater range of effect than with synthetic intracorneal ring segments (ICRS). The allogeneic nature also decreases the risk of complications such as overlying melt, necrosis, intrusion, extrusion, and migration.…”

“…The allogeneic nature also decreases the risk of complications such as overlying melt, necrosis, intrusion, extrusion, and migration. [ 11 12 13 14 15 16 17 18 ] Though CAIRS has previously been used as uniformly cut longitudinal segments,[ 1 2 3 4 5 6 7 8 9 10 ] some ectatic corneas may benefit from greater customization. In this article, we describe a new technique that we call as customized or personalized or asymmetric CAIRS to achieve tailored segments better suited to individual topographic characteristics.…”