Confocal microscopy of the in-situ crystalline lens

In vivo SS-OCT imaging of crystalline lens sutures

We demonstrate in vivo three-dimensional (3-D) visualization of crystalline lens sutures in healthy eyes using swept source optical coherence tomography (SS-OCT). Volumetric data sets of the crystalline lenses were acquired and processed to obtain enhanced contrast projection images and to extract suture patterns in both anterior and posterior lens. The results presented different types of the sutures including Y-sutures, simple and complex star sutures. Age-related changes in suture arrangement were characterized quantitatively. Crystalline lens suture imaging with SS-OCT might be a useful tool in fundamental studies on development and ageing of human lens.

Optical diagnostic technology based on light scattering spectroscopy for early cancer detection

This article reviews the application of optical diagnostic technology based on light scattering spectroscopy for minimally invasive detection of precancerous and early cancerous changes in a variety of organs. Optical spectroscopic techniques have shown promising results in the diagnosis of diseases at the cellular scale. They do not require tissue removal, can be performed in vivo and allow for real-time diagnosis. While fluorescence and Raman spectroscopy are most effective in revealing the molecular properties of tissue, the novel technique, light scattering spectroscopy, is capable of characterizing the structural properties of tissue at the cellular and subcellular scale.

In vivo confocal microscopy of the human cornea

AIMS

To describe the optics of in vivo confocal microscopy, its advantages over previous methods, and to summarise the literature that arose from its use for the observation of the human cornea. A critical review of the clinical usefulness of this new technology for the corneal examination is undertaken.

METHODS

Confocal microscopes obtain increased resolution by limiting the illumination and observation systems to a single point. Rapid scanning is used to reconstruct a full field of view and allows for "real time" viewing.

RESULTS

Coronal sections of the in situ epithelium, Bowman's membrane, stroma, and endothelium can be visualised at a resolution of 1-2 micro m. A backscattered light intensity curve allows objective measurements of sublayer thickness and corneal haze to be taken. In vivo confocal microscopy is therefore particularly useful in the areas of infective keratitis, corneal dystrophies, refractive surgery, and contact lens wear, where it aids in differential diagnosis and detection of subtle short and long term changes. Real time endothelial cell assessment can also be performed.

CONCLUSION

Because of their ability to visualise living tissue at cellular levels, confocal microscopes have proved useful additions to the current clinical tools.

Confocal microscopy of the cornea

This paper provides the clinician and the researcher with an in-depth manual on the use of a scanning-slit confocal light microscope for the clinical examination and investigation of the living human cornea in vivo. The scope of the paper includes a thorough explanation of the principles of various types of confocal microscopes as well as their limitations, a comprehensive review of the development of biomicroscopy of the eye, and a comparison of confocal microscopy and other optical techniques such as optical coherence tomography. The early work of Ridley, Goldmann and others on point illumination in early confocal instruments is described. The main part of the paper describes and illustrates the clinical examination of the living human cornea with the confocal microscope. Figures (many in color) from the normal cornea, the cornea with known parthologies, and the postsurgical cornea are selected for their educational value. Photographs of standard light microscopy of fixed, human corneal sections are compared with confocal maicroscopic images. Where appropriate, slit lamp color photographs are compared with confocal microscopic images. The clinical scanning-slit confocal microscope is an evolving instrument for biomicroscopy of the living eye.

Three-dimensional microscopic tomographic imagings of the cataract in a human lens in vivo

The problem of three-dimensional visualization of a human lens in vivo has been solved by a technique of volume rendering a transformed series of 60 rotated Scheimpflug (a dual slit reflected light microscope) digital images. The data set was obtained by rotating the Scheimpflug camera about the optic axis of the lens in 3 degree increments. The transformed set of optical sections were first aligned to correct for small eye movements, and then rendered into a volume reconstruction with volume rendering computer graphics techniques. To help visualize the distribution of lens opacities (cataracts) in the living, human lens the intensity of light scattering was pseudocolor coded and the cataract opacities were displayed as a movie.

Confocal microscopy as a tool for the investigation of the anterior part of the eye

In recent years, confocal microscopy has become a powerful tool for examining microscopic structures in the living eye. The decisive advantage of this technique is that it permits the investigation of optical sections of relatively thick (> 10 microns) specimens. Because confocal microscopy suppresses the out-of-focus blur, sharp three-dimensional images with excellent resolution can be obtained. Confocal microscopy is therefore able to provide more information than the classic methods--i.e., specular microscopy and slit-lamp biomicroscopy. This paper reviews recent applications of confocal microscopy in three fields of ophthalmology: the observation of the anatomy of the anterior parts of the eye, the investigation of these structures after local administration of drugs and, finally, the use of this technique for the diagnosis of infectious ocular diseases.

Real-time confocal laser scan microscope for examination and diagnosis of the eye in vivo

A confocal laser scan microscope is designed for the diagnosis and the examination of the anterior segment of the human eye in vivo. Any contact of the eye with the instrument optics or an immersion fluid is avoided to preclude the risk of infection or injury. Normal eyes of nine volunteers are observed and investigated. Nerve fibers and keratocytes in the stroma and the endothelium of the cornea, the capsule, and the suture of the lens, and threadlike structures in the vitreous can be observed. Cellular details in all tissues investigated can be resolved.

Real-time scanning slit confocal microscopy of the in vivo human cornea

We describe a new, nonapplanating, real-time scanning slit confocal microscope that produces unique real-time video images of the in vivo human cornea. This new real-time slit scanning confocal microscope produces en face, single-video-frame images (2-µm sections) with high contrast through the full thickness (500 µm) of the normal cornea. No frame averaging or digital image enhancement is required. The images of superficial epithelial cells, wing cells, basal epithelial cells, corneal innervation, nuclei of stromal keratocytes, and the cell bodies of the stromal keratocytes in the posterior stromal region demonstrate the unique real-time imaging characteristics. The microscope is equipped with waterimmersion microscope objectives of high numerical aperture. The microscope objective does not flatten or distort the cornea; a polymer gel is used to couple the microscope objective optically to the cornea.