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Journal Article

Real-time mapping of the corneal Sub-basal Nerve Plexus by in vivo Laser Scanning Confocal Microscopy

28 Apr 2009-Investigative Ophthalmology & Visual Science (The Association for Research in Vision and Ophthalmology)-Vol. 50, Iss: 13, pp 5669-5669
TL;DR: In this paper, a real-time mapping of the sub-basal nerve plexus was performed in a large-scale up to a size of 3.2mm x 3mm.
Abstract: The aim of the study was to produce two-dimensional reconstruction maps of the living corneal sub-basal nerve plexus by in vivo laser scanning confocal microscopy in real time. CLSM source data (frame rate 30Hz, 384x384 pixel) were used to create large-scale maps of the scanned area by selecting the Automatic Real Time (ART) composite mode. The mapping algorithm is based on an affine transformation. Microscopy of the sub-basal nerve plexus was performed on normal and LASIK eyes as well as on rabbit eyes. Real-time mapping of the sub-basal nerve plexus was performed in large-scale up to a size of 3.2mm x 3.2mm. The developed method enables a real-time in vivo mapping of the sub-basal nerve plexus which is stringently necessary for statistically firmed conclusions about morphometric plexus alterations.
Citations
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TL;DR: In vivo confocal microscopy was mainly used as a research tool to enable qualitative and quantitative study of the animal and human cornea in vivo, but nowadays commercially available instruments that have quite clearly accomplished the step from ‘bench to bedside’, permitting microscopy of the entire ocular surface.
Abstract: In the past, in vivo confocal microscopy (CM) was mainly used as a research tool to enable qualitative and quantitative study of the animal and human cornea in vivo.1–3 From the early 1990s onwards there has been a plethora of investigations of corneal structures describing findings both in healthy volunteers and in diseased patients. One of the main problems with most of these studies is their relatively low level of evidence; >80% of analysed papers published between 1990 and 2001 were classified by the American Academy of Ophthalmology's Ophthalmic Technology Assessment Committee Cornea Panel as case reports or case series.4 Nowadays, there are commercially available instruments that have quite clearly accomplished the step from ‘bench to bedside’, permitting microscopy of the entire ocular surface—that is, cornea, bulbar and palpebral conjunctiva, and lids. The axial resolution offered by competing types of confocal microscope (tandem scanning, 9 μm; slit scanning, 25 μm; laser scanning, 7–8 μm)5 affords an excellent opportunity to render tissue in three-dimensional (3D) proportions. Cell counts, 3D reconstruction,5 6 tracing of nerves7 and in vivo cell differentiation8 9 have resulted in an improved understanding of …

16 citations

References
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Journal ArticleDOI
TL;DR: In vivo confocal microscopy is 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.
Abstract: 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 μm. 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.

353 citations

Journal ArticleDOI
TL;DR: The whorl pattern of the sub-basal nerves is similar to that seen in the epithelium in corneal verticillata and may lend support to the theory that epithelial cells and nerves migrate centripetally in tandem.
Abstract: Purpose To produce a two-dimensional reconstruction map of the living human sub-basal corneal nerve plexus using in vivo confocal microscopy. Methods Laser scanning in vivo confocal microscopy was performed on three normal eyes of three healthy human subjects. Subjects were asked to fixate on targets arranged in a grid to enable examination of the cornea in a wide range of positions. Using the section mode, a mean of 573 +/- 176 images of the sub-basal plexus were obtained for each subject. The data were arranged and images were mapped for each subject into confluent montages. Results Mean dimensions of the corneal areas mapped were 4.95 +/- 0.53 mm horizontally and 5.14 +/- 0.53 mm vertically. In all subjects, the sub-basal nerve plexus appeared to radiate toward a whorl-like complex centered 1 to 2 mm inferior to the corneal apex. Outside this area, the nerve fiber bundles in the remainder of the cornea were arranged in a radiating pattern. Mean nerve density was significantly higher in the inferocentral whorl region (25,249 +/- 616 microm/mm2) compared with the central cornea (21,668 +/- 1411 microm/mm2) (Mann-Whitney U test; P = 0.05). Conclusions This is the first study to elucidate the overall distribution of sub-basal nerves in the healthy, live central to mid-peripheral human cornea by laser scanning in vivo confocal microscopy. The whorl pattern of the sub-basal nerves is similar to that seen in the epithelium in corneal verticillata and may lend support to the theory that epithelial cells and nerves migrate centripetally in tandem.

280 citations

Journal ArticleDOI
TL;DR: This perspective paper aims to provide an overview of how in vivo confocal microscopy has contributed to greater understanding of the human cornea in health, in disease, and following surgery, with a particular emphasis on quantitative data.
Abstract: In vivo confocal imaging of the cornea has evolved exponentially over the last few decades and it has increasingly emerged from the laboratory to be used in the clinical setting in relation to inherited corneal diseases, corneal infections, contact lens wear and the effects of corneal surgery. This evolution has led to significant enhancement of our knowledge of the living cornea in both its physiological and pathological states. A number of in vivo confocal microscope devices using white, and more recently coherent, light sources have been developed to provide non-invasive assessment of the corneal microstructure at a lateral resolution of 1-2 microm. The fundamental principles of in vivo confocal microscopy and the key differences between these devices are highlighted in this review. By providing a systematic review of the extensive literature on the human cornea, this perspective paper aims to provide an overview of how in vivo confocal microscopy has contributed to our greater understanding of the human cornea in health, in disease, and following surgery, with a particular emphasis on quantitative data. The utility and limitations of available data are highlighted as are possibilities for the future development of this innovative technology.

208 citations

Journal ArticleDOI
TL;DR: The main part of the paper describes the clinical applications emphasizing the anatomy of the normal and pathological cornea, and illustrates side‐effects of topical medication, contact lens wear, cross‐linking and refractive surgery.
Abstract: The demands of modern ophthalmology have evolved from descriptive findings from the slit lamp to in vivo assessment of cellular level changes. Nowadays, the latter can be provided by in vivo confocal microscopy. This article gives an overview of confocal principles using tandem scanning, scanning slit and laser scanning techniques used in ophthalmology. The main part of the paper describes the clinical applications emphasizing the anatomy of the normal and pathological cornea, and illustrates side-effects of topical medication, contact lens wear, cross-linking and refractive surgery. Finally, a summary about experimental applications, including animal studies, surface characterization and volume rendering as well as future developments, is given.

208 citations

Journal ArticleDOI
TL;DR: This is the first study to elucidate the overall distribution of sub-basal nerves in the living central to midperipheral human cornea in keratoconus, using laser scanning in vivo confocal microscopy.
Abstract: PURPOSE To produce a two-dimensional reconstruction map of the living corneal sub-basal nerve plexus in keratoconus with in vivo confocal microscopy. METHODS Four eyes of four subjects with keratoconus were examined by slit lamp biomicroscopy, Orbscan II slit-scanning elevation topography (Bausch & Lomb Surgical, Rochester, NY), and laser scanning in vivo confocal microscopy with the Heidelberg Retina Tomograph II, Rostock Corneal Module (Heidelberg Engineering, Heidelberg, Germany). Subjects were asked to fixate on targets arranged in a grid to enable in vivo confocal microscopy of the cornea in a wide range of positions. RESULTS A mean of 402 +/- 57 images were obtained for each cornea, to create confluent montages. The mean dimensions of the corneal areas mapped were 6.60 +/- 0.70 mm horizontally and 5.91 +/- 0.72 mm vertically. All corneas exhibited abnormal sub-basal nerve architecture compared with patterns previously observed in normal corneas. At the apex of the cone, a tortuous network of nerve fiber bundles was noted, many of which formed closed loops. At the topographic base of the cone, nerve fiber bundles appeared to follow the contour of the base, with many of the bundles running concentrically in this region. Central sub-basal nerve density was significantly lower in keratoconus corneas (10,478 +/- 2,188 microm/mm2) compared with normal corneas (21,668 +/- 1,411 microm/mm2; Mann-Whitney; P < 0.01). CONCLUSIONS This is the first study to elucidate the overall distribution of sub-basal nerves in the living central to midperipheral human cornea in keratoconus, using laser scanning in vivo confocal microscopy.

145 citations