Big double bubble trouble: in vivo real time demonstration of 'mixed-type bubble' and its consequent effects during deep anterior lamellar keratoplasty.
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ABSTRACT:
SUBMITTER: Selvan H
PROVIDER: S-EPMC6043615 | biostudies-literature | 2018 Jul
REPOSITORIES: biostudies-literature
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Big double bubble trouble: in vivo real time demonstration of 'mixed-type bubble' and its consequent effects during deep anterior lamellar keratoplasty.
Selvan Harathy H Yadav Shikha S Tandon Radhika R
Eye (London, England) 20180216 7
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Project description:Deep anterior lamellar keratoplasty (DALK) is a highly challenging procedure for cornea transplant that involves removing the corneal layers above Descemet's membrane (DM). This is achieved by a "big bubble" technique where a needle is inserted into the stroma of the cornea down to DM and the injection of either air or liquid. DALK has important advantages over penetrating keratoplasty (PK) including lower rejection rate, less endothelial cell loss, and increased graft survival. In this paper, we successfully designed and evaluated the optical coherence tomography (OCT) distal sensor integrated needle for a precise big bubble technique. We successfully used this sensor for micro-control of a robotic DALK device termed AUTO-DALK for autonomous big bubble needle insertion. The OCT distal sensor was integrated inside a 25-gauge needle, which was used for pneumo-dissection. The AUTO-DALK device is built on a manual trephine platform which includes a vacuum ring to fix the device on the eye and add a needle driver at an angle of 60 degrees from vertical. During the test on five porcine eyes with a target depth of 90%, the measured insertion depth as a percentage of cornea thickness for the AUTO-DALK device was 90 . 05 % ± 2 . 33 % without any perforation compared to 79 . 16 % ± 5 . 68 % for unassisted free-hand insertion and 86 . 20 % ± 5 . 31 % for assisted free-hand insertion. The result showed a higher precision and consistency of the needle placement with AUTO-DALK, which could lead to better visual outcomes and fewer complications.
| S-EPMC7013995 | biostudies-literature
Project description:The recent discovery and characterization of pre-Descemet's layer (PDL; also termed the Dua's layer or the Dua-Fine layer) has advanced the understanding of various posterior corneal pathologies and surgeries in human. This study aimed to characterize the ultrastructure of the posterior stroma and interfacial zone of Descemet's membrane (DM) in canine eyes. Eighteen canine corneo-scleral discs were included. Intrastromal air injection resulted in the formation of type 1 big bubble (BB) in 73% (n = 11/15) of corneas, with a mean diameter of 11.0 ± 1.3 mm. No type 2 BB was created. Anterior segment optical coherence tomography, histology and transmission electron microscopy confirmed that the wall of BB was composed of DM, in contact with remaining stroma (canine PDL; cPDL). The cPDL was populated with keratocytes, of varying thickness of 16.2 ± 4.2 µm in close apposition to the DM, and composed of collagen bundles arranged in transverse, longitudinal and oblique directions. The interfacial zone, between DM and cPDL, showed fibril extension in all three directions, predominantly longitudinal. Irregular extensions of DM material into cPDL stroma were observed. No long-spaced collagen was detected. In conclusion, there exists a well-defined cleavage plane between the posterior stroma and cPDL, with similar but not identical characteristics as in humans, that is revealed by pneumodissection. This adds to our understanding of the anatomy of the posterior most canine cornea, which will have significant clinical impact on posterior corneal surgery and understanding of corneal pathology in dogs.
| S-EPMC10090133 | biostudies-literature
Project description: Not available
| S-EPMC10910827 | biostudies-literature
Project description:PURPOSE:To examine big-bubble (BB) formation success rates in deep anterior lamellar keratoplasty (DALK) at various corneal depths using real-time guidance from swept-source, microscope-integrated optical coherence tomography (SS-MIOCT). METHODS:The DALK procedure was performed ex vivo with 34 human donor corneoscleral buttons on pressurized artificial anterior chambers using the BB technique employed by Anwar and Teichmann. We inserted a needle under controlled ex vivo conditions to corneal depths ranging from 40% to ?90% using real-time guidance from SS-MIOCT and injected air. BB success was then determined for each injection. RESULTS:The average needle depth for successful full BB formation was 79.9% ± 3.0% compared with 66.9% ± 2.6% for partial BB formation and 49.9% ± 3.4% for no BB formation (P < 0.0001). Expressed as stroma below the needle tip, this corresponded to 123.9 ± 20.0 ?m for successful full BB formation compared with 233.7 ± 23.8 ?m for partial BB formation and 316.7 ± 17.3 ?m for no BB formation (P < 0.0001). All other variables tested (sex, race, age, endothelial cell density, air injected, needle angle, and central corneal thickness) did not significantly affect BB formation success rates. CONCLUSIONS:BB formation in DALK is more successful if needle insertion and air injection occur at deeper corneal depth. However, ?90% corneal depth was not necessary in this ex vivo model of DALK. SS-MIOCT can be used to accurately guide the needle in real time.
| S-EPMC5067966 | biostudies-literature
Project description:PurposeTo develop and perform ex vivo testing for a device designed for semiquantitative determination of intracorneal dissection depth during big bubble (BB) deep anterior lamellar keratoplasty.MethodsA prototype device connected to a syringe and cannula was designed to determine depth of intrastromal placement based on air rebound pressure emitted by a software controlled generator. Ex vivo testing of the device was conducted on human corneas mounted on an artificial anterior chamber in three experiments: (1) cannula purposely introduced at different depths measured with anterior segment optical coherence tomography, (2) cannula introduced as per the BB technique, and (3) simulation of the BB technique guided by the device.ResultsA positive pressure differential and successful BB were observed only when the cannula was positioned within 150 microns from the endothelial plane. In all successful BB cases (21/40), a repeatable increase in tissue rebound pressure was detected, which was not recorded in unsuccessful cases. The device was able to signal to the surgeon correct placement of the cannula (successful BB) in 16 of 17 cases and incorrect placement of the cannula (unsuccessful BB) in 8 of 8 cases (94.1% sensitivity, 100% specificity).ConclusionsIn our ex vivo model, this novel medical device could reliably signal cannula positioning in the deep stroma for effective pneumatic dissection and possibly aid technical execution of BB deep anterior lamellar keratoplasty.Translational relevanceA medical device that standardizes big bubble deep anterior lamellar keratoplasty could increase the overall success rate of the surgical procedure and aid popularization of deep anterior lamellar keratoplasty.
| S-EPMC9804022 | biostudies-literature
Project description:This study evaluated the effect of air injection depth in the big-bubble (BB) technique, which is used for corneal tissue preparation in lamellar keratoplasty. The BB technique was performed on ex vivo human corneoscleral buttons using a depth-sensing needle, based on optical coherence tomography (OCT) imaging technology. The needle tip, equipped with a miniaturized OCT depth-sensing probe, was inserted for air injection at a specified depth. Inside the corneal tissue, our needle obtained OCT line profiles, from which residual thickness below the needle tip was measured. Subjects were classified into Groups I, II, III, and IV based on injection depths of 75-80%, 80-85%, 85-90%, and >90% of the full corneal thickness, respectively. Both Type I and II BBs were produced when the mean residual thicknesses of air injection were 109.7 ± 38.0 µm and 52.4 ± 19.2 µm, respectively. Type II BB (4/5) was dominant in group IV. Bubble burst occurred in 1/16 cases of type I BB and 3/16 cases of type II BB, respectively. Injection depth was an important factor in determining the types of BBs produced. Deeper air injection could facilitate formation of Type II BBs, with an increased risk of bubble bursts.
| S-EPMC6405887 | biostudies-literature
Project description: Not available
| S-EPMC10714035 | biostudies-literature
Project description:ObjectivesTo compare outcomes of femtosecond-enabled deep anterior lamellar keratoplasty (FE-DALK) and standard deep anterior lamellar keratoplasty (S-DALK).MethodsAn open label, randomized controlled trial (Kensington Eye Institute, Toronto, ON, Canada) including 100 eyes of 97 participants with either keratoconus or corneal scarring, randomized to either FE-DALK (n = 48) or S-DALK (n = 49).Primary outcomespostoperative astigmatism and surgically induced corneal astigmatism (SIA) - both at 15 months.Secondary outcomes6-, 12- and 15-month postoperative uncorrected- and best spectacle-corrected visual acuity, steep and flat keratometry, manifest sphere and astigmatism, rate of conversion to penetrating keratoplasty (PK), big-bubble success, central corneal thickness, endothelial cell count and complications.ResultsIn intention-to-treat analysis, mean postoperative astigmatism in the FE-DALK (n = 30) and S-DALK (n = 30) groups at 15 months was 7.8 ± 4.4 D and 6.3 ± 5.0 D, respectively (p = 0.282) with an adjusted mean difference of 1.3 D (95% CI -1.08, +3.65). Mean SIA (arithmetic) was 9.2 ± 7.8 and 8.8 ± 5.4 D, respectively (p = 0.838) with a mean difference of 0.4 D (95% CI -3.13, +3.85). In an analysis of successful DALK cases only, mean postoperative astigmatism in the FE-DALK (n = 24) and S-DALK (n = 20) groups at 15 months (after excluding 4 eyes with AEs) was 7.3 ± 4.4 and 6.2 ± 4.9 D, respectively (p = 0.531) with an adjusted mean difference of 0.9 D (95% CI -1.94, +3.71). Mean SIA (arithmetic) was 9.1 ± 7.8 and 7.9 ± 4.6 D, respectively (p = 0.547) with a mean difference of 1.2 D (95% CI -2.70,+5.02). Comparison of secondary outcomes showed only weak statistical evidence.ConclusionsIn this randomized controlled trial, FE-DALK and S-DALK showed comparable functional and anatomical outcomes.
| S-EPMC10482827 | biostudies-literature
Project description:Advanced keratoconus may require keratoplasty when the patient can no longer achieve functional vision with glasses and contact lenses. Deep anterior lamellar keratoplasty (DALK) has become the surgical treatment of choice due to its undisputed advantages over penetrating keratoplasty including the reduced risk of intraoperative complications, the absence of endothelial immune rejection, and the longer graft survival. Albeit "big-bubble" DALK still represents the most popular surgical method, several modifications have been developed over the years. This allowed standardization of the technique, with improved success rates and clinical outcomes. This review presents an overview on the literature on DALK surgery for keratoconus. We discuss state-of-the art surgical techniques, current evidence on the clinical outcomes and complications as well as possible future directions.
| S-EPMC9375458 | biostudies-literature
Project description:PurposeTo present a case of hematocornea occurring in a post-penetrating keratoplasty (PK) eye and to report the outcomes of deep anterior lamellar keratoplasty (DALK) performed by simple stromal peeling.ObservationsA 45-year-old female presented with hematocornea in the left eye that previously underwent PK 26 months prior for keratoconus. Clinical examination revealed a dense reddish-brown opacity within the PK graft which was associated with deep corneal neovascularization. Over 6 months, intracorneal hemorrhage developed a rust-colored appearance with minimal clearing. DALK was performed using the stromal peeling technique for post-PK eyes. Briefly, a dense partially organized hemorrhage was identified at the natural plane of separation, as confirmed by ex vivo histologic examination; after peeling of the deep corneal stroma and evacuation of the intracorneal hemorrhage, the residual bed appeared akin to pre-Descemet's layer-Descemet membrane-endothelium complex. One year after DALK, the graft remained clear with ECD of 1034 cells/mm2.Conclusions and importanceIntracorneal hemorrhage is a rare but potentially sight-threatening complication following PK. Using the stromal peeling technique, DALK can be attempted to preserve functional endothelium in post-PK eyes. In the presence of a dense intracorneal hemorrhage, the spread of erythrocytic debris within the stroma can guide deep lamellar cleavage.
| S-EPMC9883201 | biostudies-literature