Influence of corneal asymmetry on the phakometric measurement of ocular surface alignment

A. Cervino; H. Uppal; Mark C.M. Dunne

doi:10.1111/j.1475-1313.2004.00207.x

Influence of corneal asymmetry on the phakometric measurement of ocular surface alignment

A. Cervino, H. Uppal, Mark C.M. Dunne^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Phakometric measurements of corneal and crystalline lens surface alignment are influenced by corneal asymmetry in which the corneal apex does not coincide with the limbal centre. The purpose of this study was to determine the horizontal separation (e) between these corneal landmarks. Measurements were made in 60 normal eyes (30 subjects) using the Orbscan Ilz corneal analysis workstation. Our results show that both corneal landmarks typically coincide, so that e = 0, but that inter-subject variations of about ±1 mm can be expected (so that the corneal apex may fall nasal or temporal to the visual axis). This suggests that no correction for corneal asymmetry is required when estimating average amounts of ocular alignment from samples of eyes but that the measurement of e is strongly recommended for measurements in individual eyes. © 2004 The College of Optometrists.

Original language	English
Pages (from-to)	411-418
Number of pages	8
Journal	Ophthalmic and Physiological Optics
Volume	24
Issue number	5
DOIs	https://doi.org/10.1111/j.1475-1313.2004.00207.x
Publication status	Published - Sept 2004

Keywords

corneal apex
corneal topography
ocular alignment
visual axis

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10.1111/j.1475-1313.2004.00207.x

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title = "Influence of corneal asymmetry on the phakometric measurement of ocular surface alignment",

abstract = "Phakometric measurements of corneal and crystalline lens surface alignment are influenced by corneal asymmetry in which the corneal apex does not coincide with the limbal centre. The purpose of this study was to determine the horizontal separation (e) between these corneal landmarks. Measurements were made in 60 normal eyes (30 subjects) using the Orbscan Ilz corneal analysis workstation. Our results show that both corneal landmarks typically coincide, so that e = 0, but that inter-subject variations of about ±1 mm can be expected (so that the corneal apex may fall nasal or temporal to the visual axis). This suggests that no correction for corneal asymmetry is required when estimating average amounts of ocular alignment from samples of eyes but that the measurement of e is strongly recommended for measurements in individual eyes. {\textcopyright} 2004 The College of Optometrists.",

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AU - Uppal, H.

AU - Dunne, Mark C.M.

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N2 - Phakometric measurements of corneal and crystalline lens surface alignment are influenced by corneal asymmetry in which the corneal apex does not coincide with the limbal centre. The purpose of this study was to determine the horizontal separation (e) between these corneal landmarks. Measurements were made in 60 normal eyes (30 subjects) using the Orbscan Ilz corneal analysis workstation. Our results show that both corneal landmarks typically coincide, so that e = 0, but that inter-subject variations of about ±1 mm can be expected (so that the corneal apex may fall nasal or temporal to the visual axis). This suggests that no correction for corneal asymmetry is required when estimating average amounts of ocular alignment from samples of eyes but that the measurement of e is strongly recommended for measurements in individual eyes. © 2004 The College of Optometrists.

AB - Phakometric measurements of corneal and crystalline lens surface alignment are influenced by corneal asymmetry in which the corneal apex does not coincide with the limbal centre. The purpose of this study was to determine the horizontal separation (e) between these corneal landmarks. Measurements were made in 60 normal eyes (30 subjects) using the Orbscan Ilz corneal analysis workstation. Our results show that both corneal landmarks typically coincide, so that e = 0, but that inter-subject variations of about ±1 mm can be expected (so that the corneal apex may fall nasal or temporal to the visual axis). This suggests that no correction for corneal asymmetry is required when estimating average amounts of ocular alignment from samples of eyes but that the measurement of e is strongly recommended for measurements in individual eyes. © 2004 The College of Optometrists.

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Influence of corneal asymmetry on the phakometric measurement of ocular surface alignment

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