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Review
. 2020 Jul 31;20(15):4285.
doi: 10.3390/s20154285.

Biometric Measurement of Anterior Segment: A Review

Bin Liu  1   2 , Chengwei Kang  2 , Fengzhou Fang  2   3
Affiliations
Review

Biometric Measurement of Anterior Segment: A Review

Bin Liu et al. Sensors (Basel). .

Abstract

Biometric measurement of the anterior segment is of great importance for the ophthalmology, human eye modeling, contact lens fitting, intraocular lens design, etc. This paper serves as a comprehensive review on the historical development and basic principles of the technologies for measuring the geometric profiles of the anterior segment. Both the advantages and drawbacks of the current technologies are illustrated. For in vivo measurement of the anterior segment, there are two main challenges that need to be addressed to achieve high speed, fine resolution, and large range imaging. One is the motion artefacts caused by the inevitable and random human eye movement. The other is the serious multiple scattering effects in intraocular turbid media. The future research perspectives are also outlined in this paper.

Keywords: anterior segment; corneal topography; geometric measurement; tomography.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Human eye anatomy [3].
Figure 2
Figure 2
Development of the anterior segment measurement technologies.
Figure 3
Figure 3
Placido disc and representative patterns of corneal shapes [36].
Figure 4
Figure 4
Triangulation principle for corneal surface measurement [48].
Figure 5
Figure 5
Two-wavelength holographic interferometer for contour evaluation of human corneas [53].
Figure 6
Figure 6
Schematic diagram of the projection Moiré profilometry [61].
Figure 7
Figure 7
Schematic diagram of Kawara’s design [63].
Figure 8
Figure 8
Optical schematic of the Maastricht Topographer [65].
Figure 9
Figure 9
Setup for measuring the corneal surface based on the Moiré method [67].
Figure 10
Figure 10
Twyman-Green interferometer for testing the corneal surface [43].
Figure 11
Figure 11
Eye surface profiler using two symmetrical projectors [80].
Figure 12
Figure 12
Overlapping slits to map the cornea using the Scanning-slit technology [36].
Figure 13
Figure 13
Principle of Scheimpflug imaging [90].
Figure 14
Figure 14
The basic principle of ultrasound biomicroscopy (UBM). The transducer generates an ultrasound pulse. The pulse encounters the anterior segment tissues. The backscattered echoes would be detected by the same transducer, resulting in the A-scan signal to indicate the distances between the tissues. The B-scan image of the anterior segment could be obtained by scanning.
Figure 15
Figure 15
Schematic diagram of a time domain-optical coherence tomography (TD-OCT) system [85]. PD: Photodetector; BS: Beam splitter.
Figure 16
Figure 16
Schematic diagram of a spectral domain OCT (SD-OCT) system [85]. BS: Beam splitter.
Figure 17
Figure 17
Schematic diagram of a SS-OCT system [85]. BS: Beam splitter; BPD: Balanced photodetector.
Figure 18
Figure 18
Schematic diagram of a full field OCT (FF-OCT) system [172].
Figure 19
Figure 19
The trend of the development of OCT systems [147].
Figure 20
Figure 20
Single and multiple back scattered light [119].
See this image and copyright information in PMC

References

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