title: Iris concavity, corneal biomechanics, and their correlations with ocular biometry in a cohort of 10- to 12-year-old UK school boys: baseline data.
abstract: OBJECTIVE
  Pigment dispersion syndrome is associated with iris concavity. This study investigated the prevalence of iris concavity, defined as a measurement of ≤-0.1 mm, in a cohort of 10- to 12-year-old boys, and explored the relationship between iris curvature and anterior segment biometry. Associations with corneal biomechanical parameters also were explored.
  
  
  METHODS
  A cohort of school boys (n = 96) was recruited from a local school. Anterior segment optical coherence tomography (AS-OCT) was performed under accommodative and nonaccommodative conditions, and iris curvature quantified. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with the ocular response analyzer (ORA). Noncontact axial biometry was performed using laser interferometry.
  
  
  RESULTS
  The prevalence of iris concavity was 24% on distance fixation, increasing to 65% on accommodation. Variables significantly associated with nonaccommodating iris curvature were lens vault (P = 0.02) and mean keratometry (P = 0.02). For both variables acting jointly, R(2) = 0.30. Variables associated significantly with accommodating iris curvature were anterior chamber depth (P = 0.009), lens vault (P = 0.049), and mean scleral spur angle (P < 0.0001). For these three variables acting jointly, R(2) = 0.33. Significant association was found between CH and spur-to-spur distance (R(2) = 0.07, P = 0.025).
  
  
  CONCLUSIONS
  Iris concavity was a common finding in this cohort and related to anterior segment biometric parameters. Further work is required to clarify whether anatomical differences exist between iris concavity seen in the adolescent eye and that found in adults with pigment dispersion syndrome.
authors.affiliation: National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology, London, United Kingdom.
authors.forename: Ameet
authors.initials: A
authors.lastname: Shah
authors.affiliation: National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology, London, United Kingdom.
authors.forename: Sancy
authors.initials: S
authors.lastname: Low
authors.affiliation: National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology, London, United Kingdom.
authors.forename: David F
authors.initials: DF
authors.lastname: Garway-Heath
authors.affiliation: National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology, London, United Kingdom.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Foster
authors.affiliation: National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital National Health Service (NHS) Foundation Trust and University College London (UCL) Institute of Ophthalmology, London, United Kingdom Department of Epidemiology and Genetics, Institute of Ophthalmology, London, United Kingdom.
authors.forename: Keith
authors.initials: K
authors.lastname: Barton
mesh_terms: D001696:Biomechanical Phenomena; D001699:Biometry; D002648:Child; D003315:Cornea / Q000473:pathology / Q000503:physiopathology*; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D007498:Iris / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D015995:Prevalence; D041623:Tomography, Optical Coherence; D006113:United Kingdom / Q000453:epidemiology
keywords: anterior segment optical coherence tomography; corneal hysteresis; iris concavity; pigment dispersion; refractive error