title: Effect of microkeratome suction during LASIK on ocular structures.
abstract: OBJECTIVE
  To study the effect of microkeratome suction on ocular structures during LASIK.
  
  
  METHODS
  Observational, prospective case series.
  
  
  METHODS
  Twenty-one eyes of 11 patients with myopia or astigmatic myopia (8 females, 3 males) were included. The mean patient age was 36.3 years (median, 37 years; range, 24-48 years), and the mean spherical equivalent was -5.03 diopters (D) (median, -4.63 D; range, -2.38 to -8.38 D).
  
  
  METHODS
  We performed preoperative and intraoperative A-scan ultrasonography during application of suction using the Hansatome microkeratome (Bausch & Lomb Surgical, Munich, Germany) to create corneal flaps during LASIK. We also performed preoperative and postoperative B-scan ultrasonography of the posterior ocular segment with special attention to the presence and size of posterior vitreous detachment (PVD).
  
  
  METHODS
  We measured changes in the axial length, anterior chamber depth, lens thickness, and vitreous distance (distance from the posterior lens capsule to the posterior pole) during application of the microkeratome suction ring and recorded new occurrences of or increases in the size of the PVD after surgery.
  
  
  RESULTS
  The lens thickness decreased (mean change, -0.20 mm; P = 0.001; 95% confidence interval [CI], -0.11 to -0.30) in 18 eyes during application of the suction ring. The vitreous distance increased (mean change, 0.20 mm; P = 0.004; 95% CI, 0.08-0.32) in 16 eyes. No statistically significant changes were found in the anterior chamber depth (P = 0.75) or axial length (P = 0.51). After surgery, 3 of 14 eyes (21.4%) experienced PVD that did not have echographic signs of PVD before surgery. Of 7 eyes with preoperative PVD, the PVD enlarged in 1 eye (14.3%).
  
  
  CONCLUSIONS
  During application of microkeratome suction, the lens thickness decreases, whereas the vitreous distance increases, suggesting anterior traction on the posterior segment. The relationship between the observed PVD and LASIK merits further investigation.
authors.affiliation: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
authors.forename: Alireza
authors.initials: A
authors.lastname: Mirshahi
authors.forename: Thomas
authors.initials: T
authors.lastname: Kohnen
mesh_terms: D000328:Adult; D000867:Anterior Chamber / Q000473:pathology / Q000648:ultrastructure; D001251:Astigmatism / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation*; D007905:Lens Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D007908:Lens, Crystalline / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D011446:Prospective Studies; D013396:Suction / Q000009:adverse effects*; D014463:Ultrasonography; D014822:Vitreous Body / Q000473:pathology* / Q000648:ultrastructure; D020255:Vitreous Detachment / Q000000981:diagnostic imaging / Q000209:etiology*