Phakometric measurement of ocular surface radii of curvature, axial separations and alignment in relaxed and accommodated human eyes

Thomas Kirschkamp, Mark C.M. Dunne*, Jean-Cyriaque Barry

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Measurements (autokeratometry, A-scan ultrasonography and video ophthalmophakometry) of ocular surface radii, axial separations and alignment were made in the horizontal meridian of nine emmetropes (aged 20-38 years) with relaxed (cycloplegia) and active accommodation (mean ± 95% confidence interval: 3.7 ± 1.1 D). The anterior chamber depth (-1.5 ± 0.3 D) and both crystalline lens surfaces (front 3.1 ± 0.8 D; rear 2.1 ± 0.6 D) contributed to dioptric vergence changes that accompany accommodation. Accommodation did not alter ocular surface alignment. Ocular misalignment in relaxed eyes is mainly because of eye rotation (5.7 ± 1.6° temporally) with small amounts of lens tilt (0.2 ± 0.8° temporally) and decentration (0.1 ± 0.1 mm nasally) but these results must be viewed with caution as we did not account for corneal asymmetry. Comparison of calculated and empirically derived coefficients (upon which ocular surface alignment calculations depend) revealed that negligible inherent errors arose from neglect of ocular surface asphericity, lens gradient refractive index properties, surface astigmatism, effects of pupil size and centration, assumed eye rotation axis position and use of linear equations for analysing Purkinje image shifts. © 2004 The College of Optometrists.

Original languageEnglish
Pages (from-to)65-73
Number of pages9
JournalOphthalmic and Physiological Optics
Volume24
Issue number2
DOIs
Publication statusPublished - Mar 2004

Fingerprint

Lenses
Meridians
Refractometry
Crystalline Lens
Astigmatism
Surface Properties
Anterior Chamber
Pupil
Ultrasonography
Confidence Intervals
Optometrists

Keywords

  • accommodation
  • ocular alignment
  • ocular components
  • ophthalmophakometry

Cite this

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abstract = "Measurements (autokeratometry, A-scan ultrasonography and video ophthalmophakometry) of ocular surface radii, axial separations and alignment were made in the horizontal meridian of nine emmetropes (aged 20-38 years) with relaxed (cycloplegia) and active accommodation (mean ± 95{\%} confidence interval: 3.7 ± 1.1 D). The anterior chamber depth (-1.5 ± 0.3 D) and both crystalline lens surfaces (front 3.1 ± 0.8 D; rear 2.1 ± 0.6 D) contributed to dioptric vergence changes that accompany accommodation. Accommodation did not alter ocular surface alignment. Ocular misalignment in relaxed eyes is mainly because of eye rotation (5.7 ± 1.6° temporally) with small amounts of lens tilt (0.2 ± 0.8° temporally) and decentration (0.1 ± 0.1 mm nasally) but these results must be viewed with caution as we did not account for corneal asymmetry. Comparison of calculated and empirically derived coefficients (upon which ocular surface alignment calculations depend) revealed that negligible inherent errors arose from neglect of ocular surface asphericity, lens gradient refractive index properties, surface astigmatism, effects of pupil size and centration, assumed eye rotation axis position and use of linear equations for analysing Purkinje image shifts. {\circledC} 2004 The College of Optometrists.",
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Phakometric measurement of ocular surface radii of curvature, axial separations and alignment in relaxed and accommodated human eyes. / Kirschkamp, Thomas; Dunne, Mark C.M.; Barry, Jean-Cyriaque.

In: Ophthalmic and Physiological Optics, Vol. 24, No. 2, 03.2004, p. 65-73.

Research output: Contribution to journalArticle

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