title: Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study.
abstract: OBJECTIVE
  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 μm for successful full BB formation compared with 233.7 ± 23.8 μm for partial BB formation and 316.7 ± 17.3 μm 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.
authors.affiliation: *Department of Ophthalmology, Duke University School of Medicine, Durham, NC; †Department of Biomedical Engineering, Duke University, Durham, NC; ‡Corneal and External Eye Disease Department, Singapore National Eye Centre, Singapore; and §Duke-NUS Graduate Medical School, Singapore.
authors.forename: Neel D
authors.initials: ND
authors.lastname: Pasricha
authors.forename: Christine
authors.initials: C
authors.lastname: Shieh
authors.forename: Oscar M
authors.initials: OM
authors.lastname: Carrasco-Zevallos
authors.forename: Brenton
authors.initials: B
authors.lastname: Keller
authors.forename: David
authors.initials: D
authors.lastname: Cunefare
authors.forename: Jodhbir S
authors.initials: JS
authors.lastname: Mehta
authors.forename: Sina
authors.initials: S
authors.lastname: Farsiu
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Izatt
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Toth
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Kuo
mesh_terms: D000388:Air; D003315:Cornea / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D016039:Corneal Transplantation / Q000379:methods*; D058450:Endotamponade; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009339:Needles; D011247:Pregnancy; D014019:Tissue Donors; D041623:Tomography, Optical Coherence