title: Shape Changes of the Anterior Lamina Cribrosa in Normal, Ocular Hypertensive, and Glaucomatous Eyes Following Acute Intraocular Pressure Elevation.
abstract: OBJECTIVE
  The purpose of this study was to estimate and compare changes in anterior lamina cribrosa (LC) morphology in normal, ocular hypertensive (OHT), and glaucomatous eyes following acute elevations in intraocular pressure (IOP).
  
  
  METHODS
  The optic nerve heads (ONHs) of 97 subjects (17 OHT, 19 primary open-angle glaucoma [POAG], 31 primary angle-closure glaucoma [PACG], and 30 normal subjects) were imaged using optical coherence tomography (OCT). Intraocular pressure was raised twice by applying forces to the anterior sclera, using an ophthalmodynamometer. After each IOP elevation, IOP was held constant and measured; each ONH was rescanned with OCT. In each OCT volume, the anterior LC was enhanced, delineated, and its global shape index (GSI) calculated and compared across groups.
  
  
  RESULTS
  The baseline IOP was 17.5 ± 3.5 mm Hg and was increased to 38 ± 5.9 mm Hg and then to 46.5 ± 5.9 mm Hg. At the first IOP increment, mean GSI was significantly smaller than that at baseline in normal subjects and glaucoma subjects (P < 0.05) but not in OHT subjects (P = 0.12). For the second IOP increment, the mean GSI was significantly smaller than that at baseline in normal subjects and in OHT eyes (P < 0.05). After adjusting for age, sex, and baseline IOP, the LC of POAG eyes was found to be significantly more posteriorly curved than that of normal subjects (P = 0.04).
  
  
  CONCLUSIONS
  Acute IOP elevations altered anterior LC shape in a complex nonlinear fashion. The LC of POAG eyes was more cupped following acute IOP elevations compared to that of normal subjects.
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore.
authors.forename: Tin A
authors.initials: TA
authors.lastname: Tun
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore.
authors.forename: Sri Gowtham
authors.initials: SG
authors.lastname: Thakku
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore.
authors.forename: Owen
authors.initials: O
authors.lastname: Png
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore.
authors.forename: Mani
authors.initials: M
authors.lastname: Baskaran
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore.
authors.forename: Hla M
authors.initials: HM
authors.lastname: Htoon
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore.
authors.forename: Sourabh
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore.
authors.forename: Monisha E
authors.initials: ME
authors.lastname: Nongpiur
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore 3Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Cheng
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 2Duke-National University of Singapore Medical School, Singapore 3Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 4National Institute of Health Research Biomedical Research Centre, Moorfields Eye Hospital, National Health Service Foundation Trust, and University College London (UCL) Institute of Ophthalmology, London, United Kingdom 5Discipline of Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Strouthidis
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre Singapore 6Ophthalmic Engineering and Innovation Laboratory, Department of Biomedical Engineering, National University of Singapore, Singapore.
authors.forename: Michaël J A
authors.initials: MJ
authors.lastname: Girard