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Visual Inspection of Tissues with Certain Endoscopes and Other Optical Devices
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
We have seen that the ophthalmoscope permits visualization of the features of inner surface of the retina, including signs of ARMD, damage from diabetes, and mechanical damage from trauma. The slit lamp, on the other hand, allows examination of the optical structures of the eye for pathologies, damage, and foreign objects, including the cornea, the lens, the iris, and the vitreous body. The components of a slit lamp consist of a long working distance, binocular microscope, normally directed in the horizontal plane at the eye under study. The microscope can be of the zoom type, giving magnification in the range of 5× to ∼50×. The (azimuth) angle of the microscope axis with respect to the eye's gaze axis can be varied in the horizontal plane. The slit lamp also has a flexible light source based on a high-intensity halogen lamp. The lamp filament is projected onto a slit (adjustable in width, height, and angle with the vertical). The slit's image is in turn, directed to the desired part of the eye by a focusing lens. A cobalt blue filter can be inserted into the slit beam (pass peak at ∼400 nm) to selectively excite the 550 nm green fluorescence of the vital stain, fluorescein sodium. Fluorescein is used to identify corneal abrasions, cuts, etc. where it selectively concentrates. A longwave-pass filter is used over the microscope objective to cut the blue light and to improve contrast of the fluorescent images.
Diagnostic Devices
Published in Laurence J. Street, Introduction to Biomedical Engineering Technology, 2016
A slit lamp is a tool commonly used in eye examinations. It provides a stable, adjustable platform for the patient to rest their head, keeping it comfortably but reliably in place during the examination (Figure 4.23).
Risk assessment of benzalkonium chloride in cosmetic products
Published in Journal of Toxicology and Environmental Health, Part B, 2018
Seul Min Choi, Tae Hyun Roh, Duck Soo Lim, Sam Kacew, Hyung Sik Kim, Byung-Mu Lee
Labbe et al. (2006) examined the ocular surface toxicity of BAC in Lewis rats. Animals were instilled twice per day for 11 days with 0.1% or 0.5% BAC, with balanced salt solution (BSS) used as a control. The adverse effects on the cornea and conjunctiva were evaluated by slit-lamp examination, fluorescein test, impression cytology, in vivo confocal microscopy, and histology. BAC induced marked alterations in the corneoconjunctival surface, and significantly diminished tear production compared with control.