Clinical microscopy of the cornea utilizing optical sectioning and a high-numerical-aperture objective

Abstract

A doublet contact element was added to a long-working-distance objective to increase the numerical aperture to 0.75 and to maintain the focus during in vivo examination of the eye. Optical sectioning by use of confocal slits permits visualization of weakly scattering structures within the cornea. With photographic film and a 1/60-s exposure time to limit the effect of eye movement, an effective optical section half-thickness of approximately 20 microns was realized. Structures observed in the cornea include epithelial cells (surface, wing, and basal cells), nerve-fiber bundles in the subepithelial region, keratocytes and inflammatory cells in the stroma, and endothelial cells.

Spectrally-modulated full-field optical coherence microscopy for ultrahigh-resolution endoscopic imaging

“…In addition, since we were interested in detecting sample arm light only from the focus, we selected a sufficiently large L so that the unwanted signal from the conjugate depth position was minimized. When the light at sample arm is focused at z = L, (2) with L >> δl and κδl < 1. The processed image is given by (3) In order to optimize spectral fringe contrast and SNR, the modulation amplitude and phase were adjusted to maximize the processed signal.…”

“…Imaging modalities that make use of endogenous contrast, such as reflectance confocal microscopy (CM) [1,2] and optical coherence tomography (OCT) [3,4] show great promise for endoscopic microscopy. However, both techniques have technical requirements that make endoscopic subcellular imaging difficult.…”

Keratocyte Density

“…33 Depths of features, such as the sub-basal nerves, a laser in situ keratomileusis interface, or the endothelium when measuring corneal thickness, have been determined by identifying the feature in a particular frame, either by visual inspection or by brightness. 24 -26 Distance is determined from the number of frames between the image of the object and a reference (such as the epithelial surface), the frame rate, and the scan speed.…”

“…7,9,13-15,29 -32 Principles of operation and differences between point-scanning and slit-scanning confocal microscopes have been reviewed. 2,4,18,33 An important difference between the Tandem Scanning and the current ConfoScan 3 confocal microscopes is the size and shape of the confocal apertures. The pinhole apertures of the Tandem Scanning microscope are 20 to 30 m in diameter, depending on the specific instrument, arranged in a spiral array on a disk (Nipkow disk), while the slit apertures of the ConfoScan 3 are approximately 180 m wide.…”

Preliminary Evaluation of Noninvasive Microscopic Imaging Techniques for the Study of Vocal Fold Development

“…Techniques such as optical coherence tomography (OCT), an interferometric technology that provides cross-sectional images of backscattered light, 12 and reflectance confocal microscopy (RCM), 13,14 which provides en face virtual sections with cellular resolution, are being integrated in practices in the fields of ophthalmology, [15][16][17][18] gastroenterology, [19][20][21] cardiology, 22 and dermatology. 23,24 Imaging of porcine and human cadaveric true vocal fold specimens with OCT revealed visualization of the superficial Ep, basement membrane, LP, and thyroarytenoid muscle.…”