title: Correlation Between Corneal Button Size and Intraocular Pressure During Femtosecond Laser-Assisted Keratoplasty.
abstract: OBJECTIVE
  To evaluate changes in intraocular pressure (IOP) in recipient and donor eyes during femtosecond laser-assisted keratoplasty (FLAK) and to assess for differences in the diameter of trephinated corneal buttons according to changes in pressure.
  
  
  METHODS
  Twenty porcine whole eyes (recipient model) and 20 porcine-corneoscleral rims (donor model) were prepared, and anterior chamber pressures were measured using a fiberoptic sensing device (Opsens, Quebec, Canada) during the femtosecond laser corneal cutting process. To determine the diameter of corneal buttons, 10 porcine whole eyes (recipient model) and 12 corneoscleral rims (donor model) of each baseline IOP were cut with the femtosecond laser programmed to the following pattern: "vertical side cut"; 1200 μm (depth), 8 mm (diameter). Digital photographs were obtained using microscopy and subsequently analyzed.
  
  
  RESULTS
  The IOP (mean ± SD) for the recipient model was 10.2 (±0.9) mm Hg at baseline and ranged from 96.6 (±4.5) to ∼138.4 (±3.8) mm Hg during the corneal cutting process. This shows that the maximum IOP during FLAK increased 13.5 times compared with baseline. In the donor model, the mean pressure elevation from baseline artificial anterior chamber (AAC) pressure to corneal cutting was 15.8 (±5.4) mm Hg. This showed a positive correlation with baseline IOP [correlation coefficient (CC) = 0.827, P = 0.006]. As the baseline IOP in the recipient eye increased, trephinated corneal button size was reduced by up to 3.9% in diameter (CC = -0.945, P = 0.015). In addition, in donor eyes, the diameter was decreased by up to 11.7% as the baseline AAC pressure increased (CC = -0.934, P = 0.006).
  
  
  CONCLUSIONS
  During the FLAK procedure, the IOP increases in both recipient and donor eyes. The diameter of the trephinated donor and recipient corneal buttons was decreased as the initial baseline IOP increased. Ophthalmic surgeons can determine the AAC pressure based on the baseline IOP in the recipient patient.
authors.affiliation: *Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea; and †Department of Ophthalmology, Yeouido St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Mihyun
authors.initials: M
authors.lastname: Choi
authors.forename: Yong Eun
authors.initials: YE
authors.lastname: Lee
authors.forename: Woong-Joo
authors.initials: WJ
authors.lastname: Whang
authors.forename: Young-Sik
authors.initials: YS
authors.lastname: Yoo
authors.forename: Kyung-Sun
authors.initials: KS
authors.lastname: Na
authors.forename: Choun-Ki
authors.initials: CK
authors.lastname: Joo
mesh_terms: D000818:Animals; D000867:Anterior Chamber / Q000503:physiopathology; D003315:Cornea / Q000601:surgery*; D004195:Disease Models, Animal; D007429:Intraocular Pressure / Q000502:physiology*; D015948:Keratoplasty, Penetrating / Q000379:methods*; D012590:Sclera / Q000601:surgery; D013552:Swine; D014065:Tonometry, Ocular