Dr. Raiyan T. Zaman Profile

Dr. Raiyan T. Zaman

at Massachusetts General Hospital

SPIE Involvement:

Author

SPIE Journal Paper | 1 July 2011 Open Access

Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent

Raiyan Zaman, Brandon Nichols, Henry Rylander, Tianyi Wang, James Tunnell, Ashley Welch, Narasimhan Rajaram

JBO, Vol. 16, Issue 07, 077008, (July 2011) https://doi.org/10.1117/12.10.1117/1.3599985

KEYWORDS: Sclera, Blood vessels, Optical properties, Blood, Absorption, Scattering, Eye, Tissue optics, Tissues, Phase modulation

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Proceedings Article | 12 February 2009 Paper

Changes in morphology and optical properties of sclera due to hyperosmotic agent

Raiyan Zaman, Henry Rylander, Narasimhan Rajaram, Tianyi Wang, Nitin Asokan, James Tunnell, Ashley Welch

Proceedings Volume 7175, 71750D (2009) https://doi.org/10.1117/12.809701

KEYWORDS: Sclera, Optical properties, Scattering, Absorption, Blood vessels, Eye, Oxygen, Blood, Light scattering, Eye models

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The primary and the secondary goals of this study were to investigate the change in morphology and optical properties of sclera due to a hyperosmotic agent i.e. 100% anhydrous glycerol. We performed our experiments in vivo on the sclera of 8 rabbits and 3 miniature pigs. All the animals were under anesthetic for the entire experiment according to an approved protocol. The position of the eye was stabilized with a suture placed in the limbus. Glycerol was delivered to sclera in 2 methods (i) injection (using a hypodermic needle 27G ½), (ii) direct application after 0.3 cm incision at conjunctiva. A camera attached to a slit lamp was used to capture the morphological changes of the sclera. For the secondary goal we used a diffuse optical spectroscopy (DOS) system with a linear fiber arrangement to measure reflectance from the sclera before and after application of glycerol. The probe source-detector separation was set to 370 μm for optimal penetration depth. We fit the measured diffuse reflectance to a Lookup Table (LUT)-based inverse model specific to our probe geometry to determine the scattering and absorption properties of the sclera. This method estimated the size and density of scatterers, absorbers-blood volume fraction, melanin concentration, oxygen saturation, and blood vessel size. The results illustrated that the initial clearing of sclera started 3 minutes after injecting glycerol to sclera. The sclera became completely transparent at 8 minutes and stayed clear for 10-15 minutes. During this time the choroid layer was visible through sclera. The clear sclera became less transparent over next 11 minutes and became completely opaque once we applied 0.9% saline to hydrate the sclera. These dehydration and hydration cycles were repeated 4 times for each eye and the results were consistent for all animal models. When glycerol was applied directly to sclera after the incision at the conjunctiva, the sclera became transparent instantaneously. For the secondary goal, the changes in optical properties of sclera were monitored during the dehydration and hydration cycles. The reduced scattering coefficient decreased when glycerol was injected and it further reduced with direct application. The scattering increased after re-hydration. We also measured the blood volume fraction, melanin concentration, oxygen saturation, and blood vessels diameter to calculate absorption coefficient with the DOS system. This study provided a novel way to identify morphological changes of sclera in addition to measuring changes in optical properties due to hyper osmotic agent. The changes in optical properties were consistent with the morphological changes in sclera during the dehydration and hydration cycles.

Proceedings Article | 20 February 2008 Paper

Porcine skin ED50 damage thresholds for 1214 nm laser irradiation

Bo Chen, Jeffrey Oliver, Rebecca Vincelette, Ginger Pocock, Raiyan Zaman, Ashley Welch

Proceedings Volume 6854, 685406 (2008) https://doi.org/10.1117/12.761380

KEYWORDS: Skin, Laser damage threshold, Laser irradiation, Absorption, Tissues, Safety, Scattering, Tissue optics, Standards development, Injuries

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Proceedings Article | 20 February 2008 Paper

Enhancement of light in tissue using hyper-osmotic agents

Raiyan Zaman, Bo Chen, Ashwin Parthasarathy, Arnold Estrada, Ardien Ponticorvo, Henry Rylander, Andrew Dunn, Ashley Welch

Proceedings Volume 6854, 68541F (2008) https://doi.org/10.1117/12.763241

KEYWORDS: Skin, Speckle, Blood circulation, Blood vessels, Arteries, Veins, Tissue optics, Doppler tomography, Blood, Capillaries

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Conference Committee Involvement (1)

Optics and Ionizing Radiation

3 February 2020 | San Francisco, California, United States

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