Conformation of the anterior segment in human myopia

Hetal Buckhurst*, Bernard Gilmartin, Robert Cubbidge, Nicola S. Logan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Purpose: Topography of the in vivo anterior segment is of relevance in understanding its role in myopia and in the development of ocular surgical procedures. Using 3D magnetic resonance (MR) images of the human eye, regional variations in surface area (SA) and bulbosity of four anterior segment regions were investigated in association with refractive status (Rx), axial length (AL) and total ocular volume (OV). Methods: T2-weighted ocular MR images from 43 adults aged 18–40 years (mean ± SD; 28.65 ± 6.20) comprising 20 non-myopes (≥−0.50) 0.57 ± 1.38 and 23 myopes (<−0.50) −6.37 ± 4.23 MSE (D) were collected. 2D representations of each quadrant (superior-temporal [ST], superior-nasal [SN], inferior-temporal [IT] and inferior-nasal [IN]) of the anterior section (3.5–9 mm) were fitted with second-order polynomials. Polynomials were integrated and rotated about the x-axis to generate SA; dividing the SA by 4 provided relative quadrantial SA. The x 2 coefficient provides indices of bulbosity. OV was derived from the 3D MRI scans. Rx and AL were measured using cycloplegic autorefraction and the Zeiss IOLMaster, respectively. One- and two-way repeated-measures ANCOVAs tested differences in SA and bulbosity for Rx, gender, ethnicity and age. Pearson's correlation coefficient tested the relationship between MRI-derived metrics and biometry. Results: Significant differences in SA were observed between quadrants (p < 0.001) with differences between ST versus IN, IN versus IT and SN versus IT. An interaction effect (p = 0.01) for Rx suggested smaller temporal (ST and IT) and larger nasal (SN and IN) SA in myopes. AL and myopic Rx were negative correlated (p < 0.05) with SA at IN, SN and IT. OV was significantly associated with SA at ST. Bulbosity showed no regional differences nor an effect of AL or Rx. Conclusion: Significant regional variation in SA exists across the anterior segment that is modulated by Rx and AL. It is unclear whether these structural characteristics are a precursor or consequence of myopia and may warrant investigation when developing biomechanical interventions.

Original languageEnglish
Pages (from-to)368-376
Number of pages9
JournalOphthalmic and Physiological Optics
Issue number3
Early online date7 Feb 2023
Publication statusPublished - May 2023

Bibliographical note

Copyright © 2023 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.


  • anterior segment shape
  • MRI
  • myopia
  • surface area and eye shape


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