Dataset Information

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

ABSTRACT:

Purpose

The purpose of this study was to explore the optimal shape of customized lenticules for stromal lenticule addition keratoplasty (SLAK) for off-centered ectasia.

Methods

Two different methods to create ex vivo models of eccentric-keratoconus were investigated. Twelve human corneas were used to create model 1 by a hyperopic photorefractive keratectomy (PRK), and model 2 by masked phototherapeutic keratectomy (PTK) on the anterior corneal surface, whereas both types received myopic ablation of the posterior surface. Keratoconus models underwent a modified femtosecond laser (FSL) flap-cut to create stromal pockets. Sixteen human corneas underwent FSL dissection to obtain four lenticule types: type I (planar) and type II (negative) lenticules were used without modifications, whereas type III (customized-planar), and type IV (customized-negative) lenticules underwent further masked-PRK to obtain an asymmetric bow-tie shape. Topographic, aberrometric analysis, and anterior segment optical coherence tomography (AS-OCT) were performed in all recipient corneas before and after lenticule implantation.

Results

Keratoconus model was successfully reproduced. Tomographic analysis showed a significant inferiorly decentered corneal steepening with coherent stromal thinning. Model 2 reproduced better the curvature of real keratoconus. Lenticules type I implantation induced a homogeneous corneal thickening, type III produced higher thickening in the inferior half of the cornea. Type II determined a maximal peripheral pachymetric increase, with a gradual reduction toward the center, and type IV presented an asymmetric peripheral thickening. Topographic assessment showed a cone apex flattening in all cases, but it was significantly higher in types II and IV. Customized lenticules improved significantly corneal surface regularity regarding types I and II.

Conclusions

The approach of customizing lenticules by increasing their asymmetry and tailoring the re-shaping effects, may improve SLAK outcomes in eccentric keratoconus.

SUBMITTER: Nubile M

PROVIDER: S-EPMC11309033 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature

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Publications

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

Nubile Mario M Alio Del Barrio Jorge L JL Cerino Luca L Salgari Niccolò N El Zarif Mona M Totta Michele M Lanzini Manuela M Mastropasqua Leonardo L

Investigative ophthalmology & visual science 20240801 10

<h4>Purpose</h4>The purpose of this study was to explore the optimal shape of customized lenticules for stromal lenticule addition keratoplasty (SLAK) for off-centered ectasia.<h4>Methods</h4>Two different methods to create ex vivo models of eccentric-keratoconus were investigated. Twelve human corneas were used to create model 1 by a hyperopic photorefractive keratectomy (PRK), and model 2 by masked phototherapeutic keratectomy (PTK) on the anterior corneal surface, whereas both types received ...[more]

PMID: 39102261

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Project description:IntroductionRefractive stromal lenticules from Small Incision Lenticule Extraction (SMILE), though usually discarded, hold a potential for various ophthalmic applications, including refractive correction, stromal volume expansion, and biomechanical strengthening of the cornea.ObjectivesTo investigate the effect of lenticule customization on lenticule neurite length profile and the excitatory response (calcium signaling) and the potential of reinnervation.MethodsHuman and porcine stromal lenticules were treated by (1) excimer laser reshaping, (2) ultraviolet A-riboflavin crosslinking (CXL), and (3) decellularization by sodium dodecyl sulfate (SDS), respectively. The overall neurite scaffold immuno-positive to TuJ1 (neuron-specific class III β-tubulin) expression and population of active neurite fragments with calcium response revealed by L-glutamate-induced Fluo-4-acetoxymethyl ester reaction were captured by wide-field laser-scanning confocal microscopy, followed by z-stack image construction. The NeuronJ plugin was used to measure neurite lengths for TuJ1 (NL-TuJ1) and calcium signal (NL-Ca). Reinnervation of lenticules was examined by the ex vivo grafting of chick dorsal root ganglia (DRG) to the decellularized human lenticules. Differences between groups and controls were analyzed with ANOVA and Mann-Whitney U test.ResultsThe customization methods significantly eliminated neurites inside the lenticules. NL-TuJ1 was significantly reduced by 84% after excimer laser reshaping, 54% after CXL, and 96% after decellularization. The neurite remnants from reshaping and CXL exhibited calcium signaling, indicative of residual excitatory response. Re-innervation occurred in the decellularized lenticules upon stimulation of the grafted chick embryo DRG with nerve growth factor (NGF 2.5S).ConclusionAll of the lenticule customization procedures reduced lenticule neurites, but the residual neurites still showed excitatory potential. Even though these neurite remnants seemed minimal, they could be advantageous to reinnervation with axon growth and guidance after lenticule reimplantation for refractive and volume restoration of the cornea.

Project description:PurposeTo introduce cases of the use, as patch grafts, of stromal lenticules obtained by small incision lenticule extraction (SMILE) surgery.ObservationsCase 1 was a 79-year-old man who presented with Ahmed-valve-tube exposure in his left eye. His uncorrected visual acuity (UCVA) was 20/40, best-corrected visual acuity (BCVA) 20/32, and intraocular pressure (IOP) 11 mmHg. He was treated with stromal lenticule patch that had been extracted by SMILE surgery. The patch was positioned underneath of the conjunctiva and sutured to it. At postoperative 8 months, the graft site was well maintained without Ahmed valve-tube exposure, the UCVA was 20/32, BCVA 20/20, and IOP 12 mmHg.Case 2 was a 60-year-old man who presented with Ahmed-valve-tube exposure in his right eye. His UCVA was finger-count (FC) 30 cm, his BCVA 20/125, and his IOP 14 mmHg. He was treated with stromal lenticule patch by the same method as employed in case 1. At postoperative 10 days, tube re-exposure and displacement of the Ahmed valve external plate toward the limbus area occurred due to loosening of the anchoring suture. So, we removed the Ahmed valve device, which had been implanted in the supero-temporal area, and performed new Ahmed valve implantation, with a stromal lenticule flap instead of a partial scleral flap, in the supero-nasal area. As of 6 months post-reoperation, the patient was stable, with UCVA 20/200, BCVA 20/40 and IOP 13 mmHg.Case 3 was a 74-year-old man who presented with bullous keratopathy in his right eye, which was blind. Due to severe adhesions, his conjunctiva could not cover the entire cornea. Therefore, we performed a stromal lenticule patch graft with conjunctival advance flap. At postoperative 3 months, the patient's right eye was stable, without displacement or melting of the lenticule graft.Conclusions & importanceIt is suggested that the stromal lenticule, with its biocompatibility, sufficient strength, ease of handling and low cost, is a useful patch graft for various therapeutic purposes in the ophthalmic field.

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Dataset Information

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

Purpose

Methods

Results

Conclusions

Publications

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

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