Pressure dependent direct transtissue transmission of eyewall, sclera and vitreous body in the range of 350-1050nm

Philipp S Koelbl; Nicole Sieber; Christian Lingenfelder; Frank H J Koch; Svenja Deuchler; Martin Hessling

doi:10.1016/j.zemedi.2020.02.003

Pressure dependent direct transtissue transmission of eyewall, sclera and vitreous body in the range of 350-1050nm

Z Med Phys. 2020 Aug;30(3):201-210. doi: 10.1016/j.zemedi.2020.02.003. Epub 2020 Mar 4.

Authors

Philipp S Koelbl¹, Nicole Sieber¹, Christian Lingenfelder², Frank H J Koch³, Svenja Deuchler³, Martin Hessling⁴

Affiliations

¹ Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081 Ulm, Germany.
² Pharmpur GmbH, Messerschmittring 33, D-86343 Koenigsbrunn, Germany.
³ Clinic of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany.
⁴ Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081 Ulm, Germany. Electronic address: martin.hessling@thu.de.

PMID: 32143979
DOI: 10.1016/j.zemedi.2020.02.003

Abstract

Purpose: For transscleral application of optical radiation or light to the eye, it is important to know the transmission and absorbance of the tissue layers of the eyewall. The impact of photochemical energy to the retina located directly at the point of contact with the radiation emitter must be considered as well as the absorbance in choroid and retina. Therefore, the direct transmission of ex vivo porcine eyewalls and vitreous body were measured in this study.

Methods: At ex vivo porcine eyes (N=221) pressure dependent transmission measurements were performed with a pressure inducing setup. Pressure and wavelength dependent direct transmission of eyewall and vitreous body of porcine eyes were described for different applied pressures (23mmHg, 78mmHg and 132mmHg). The transmissions were investigated within the spectral range of 350-1050nm. In addition to the complete eyewall transmission measurements, the transmission of sclera, vitreous body and water was measured individually and the transmission of retina and choroid was calculated.

Results: With increasing wavelength and pressure, a significant transmission increase of the eyewall could be achieved (p<0.05). At 400nm and 132mmHg the transmission raised to 0.10%. At 1050nm it increased up to a value of 12.22%. In the visible spectrum, the direct transmission was always below 3.17%. The differences in eyewall transmission of eyes with different iris colors were significant at low pressure. With increasing pressure, the effect strength decreased and the differences lost their significance.

Conclusions: The pressure and wavelength dependent direct transmission of the eyewall and the vitreous body significantly increased with increasing pressure. This results are benefical for technical and clinical safety, research and development of illumination devices. It is necessary to know the intraocular brightness in the eye during diaphanoscopy, photocoagulation application to determine hazards.

Keywords: Choroid; Intraocular illumination; Iris color; Pressure dependent transmission; Retina; Transtissue transmission.

MeSH terms

Animals
Pressure*
Sclera / physiology*
Swine
Vitreous Body / physiology*