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Thomas Gast, Brett King, Peter Harrington, Kaitlyn Sapoznik, Ting Luo, Stephen A Burns; Modifications of AOSLO to allow Imaging Human Ocular Angle Structures. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4626.
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© ARVO (1962-2015); The Authors (2016-present)
Given the significance of glaucoma as an ophthalmic disease and the very low resolution and magnification of the ocular angle structures as seen during the clinical examination using gonioscopy, we elected to improve the understanding of the structures of the ocular angle in health and disease by imaging this area using AOSLO.
A specially modified goniolens was created by eccentrically affixing a 12mm button lens to the anterior surface of a clinical single mirrored goniolens. This button lens provided optical correction for infinity at the correct distance for the angle structures. Contact of this lens with the anterior surface of the cornea avoids the total internal reflection problem of imaging the ocular angle. On a kinematic mount the lens is mounted on springs allowing free anterior/posterior movement avoiding excessive pressure on the eye. The pivet point of the AOSLO is placed within the goniolens at the mirror surface. The subjects are topically anesthetized, mounted securely in a motorized head rest with forehead, temple and chin rests. A strap is placed behind the head. An adjustable closed blade lid speculum is placed and taped to the temple; goniosol is applied to the eye and to the goniolens; and then the subject's cornea is brought near the posterior surface of the goniolens using a total of 6 videocameras including 2 borescope cameras on the kinematic lens mount for close visualization of the goniolens-cornea conjugation. A borescope camera mounted just superior to the imaging beam allows visualization of the spreading of the goniosol as contact is made. The head is advanced until the goniosol covers the interface. Imaging then proceeds with fixation control using the non-imaged eye. Calibration was done by objective measurement of a structure within an anatomically accurate model eye.
AOSLO imaging has been successfully done on 6 non-glaucomatous subjects ages 28 to 67. There is excellent correspondence of the high resolution images with clinical imaging of structures such as iris processes and the scleral spur.
The technology of AOSLO has been applied to imaging the structures of the ocular angle including the trabecular meshwork. The resolution is high. It is hoped that this technology will enable an improved understanding of angular structures and their relationship to glaucoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Image of gonioapparatus (labelled)
Mid-magnification (size 3) image of small iris process
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