title: Anterior Segment Biometry Changes with Cycloplegia in Myopic Adults.
abstract: OBJECTIVE
  To determine the effect of cycloplegia on corneal thickness, corneal curvature, anterior chamber depth (ACD), angle-to-angle (ATA) and white-to-white (WTW) distances, and axial length (AL).
  
  
  METHODS
  Changes in corneal thickness, corneal curvature, ACD, ATA and WTW distances, and AL with and without cycloplegia were analyzed in 31 eyes of 31 young myopic adults, aged 26.4 ± 3.0 years. Pentacam was used to measure the corneal thickness, corneal volume, and corneal curvatures. Visante optical coherent tomography (OCT) measured corneal thickness, ATA distance, ACD, and pupil size. The AL and WTW distance were measured using IOLMaster.
  
  
  RESULTS
  Cycloplegia induced significant flattening of corneal curvatures (p = 0.019, 0.001, and 0.003 for anterior sagittal, posterior tangential, and posterior sagittal curvatures, respectively). The difference in the posterior corneal curvature was greater in corneas with steeper posterior curvatures. Cycloplegia also induced significant deepening of ACD (0.08 ± 0.06, p < 0.001) and widening of both WTW (0.42 ± 0.43, p < 0.001) and ATA (0.08 ± 0.17, p = 0.015) distances. The cycloplegia-related increase in the ATA distance correlated negatively with AL (r = -0.361, p = 0.046), whereas the cycloplegia-related increase in WTW distance correlated weakly with the increase in ACD (r = 0.347, p = 0.056) but not with AL. The AL did not change with cycloplegia. Pentacam measured a slightly thicker cornea than OCT (p = 0.002). Both Pentacam and OCT detected a significant increase in corneal thickness of 4 μm, which could be attributed to reflex tearing, after cycloplegia.
  
  
  CONCLUSIONS
  Cycloplegia resulted in deeper ACD, greater ATA distance, and flatter corneal curvatures. Surgeons should be aware of these cycloplegia-related alterations for more accurate phakic/functional intraocular lens selection and better refraction results.
authors.affiliation: *MD Department of Ophthalmology, Far Eastern Memorial Hospital, Ban-Chiao District, New Taipei City, Taiwan (S-WC, AYL, P-FS); Department of Community Health Development, Ban-Chiao District, New Taipei City, Taiwan (S-WC); and Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan (S-WC).
authors.forename: Shu-Wen
authors.initials: SW
authors.lastname: Chang
authors.forename: Andy Y
authors.initials: AY
authors.lastname: Lo
authors.forename: Po-Fang
authors.initials: PF
authors.lastname: Su
mesh_terms: D000328:Adult; D000869:Anterior Eye Segment / Q000187:drug effects / Q000502:physiology; D001699:Biometry / Q000379:methods; D002924:Ciliary Body / Q000187:drug effects / Q000502:physiology; D003315:Cornea / Q000503:physiopathology; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D009130:Muscle, Smooth / Q000502:physiology; D009184:Mydriatics / Q000008:administration & dosage*; D009216:Myopia / Q000503:physiopathology*; D011680:Pupil / Q000187:drug effects* / Q000502:physiology*; D041623:Tomography, Optical Coherence; D014331:Tropicamide / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D009184:Mydriatics; D014331:Tropicamide