In vivo confocal microscopy of the human cornea

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.

Identifying relationships between tomography-derived corneal thickness, curvature, and diameter and in vivo confocal microscopic assessment of the endothelium in healthy corneas of young adults

“…[35][36][37] The relationship between CCT and age has been extensively studiedFalthough the majority of authors report a gradual decrease in CCT with advancing age after infancy, [38][39][40][41][42] in contrast, others have reported no change or an increase in CCT with advancing age. 36,43 The relationship between significant endothelial dysfunction and increased corneal thickness is well established, 3,[44][45][46] and recognized causes of increased corneal thickness include anterior segment disease and previous intraocular surgery. 23,42,47,48 However, the relationship between corneal thickness and ECD in the normal eye throughout life has yet to be fully established, with few reports in the literature investigating a possible relationship.…”

Mechanical Complications Induced by Silicone Hydrogel Contact Lenses

“…They can be blinked away or leave depressions on the corneal epithelium on lens removal. 7,12 These depressions are best observed with fluorescein instilled in the eye as the dye pools in the imprinted areas ( Fig. 2) and are usually resolved within 24 hrs.…”

“…They are composed primarily of mucin, 1 and their sizes have been reported to range between 20 and 200 mm in diameter. [2][3][4][5][6][7] Because they can be significantly larger than the thickness of the postlens tear film [8][9][10][11] or the corneal epithelium, it is not surprising that some mucin balls can become deeply embedded into the cornea. They can be blinked away or leave depressions on the corneal epithelium on lens removal.…”

A fully automatic nerve segmentation and morphometric parameter quantification system for early diagnosis of diabetic neuropathy in corneal images

“…is a covariance measure for x and y. C 1 =(k 1 L) 2 , C 2 =(k 2 L) 2 are small constants used to maintain stability when either ( ) or ( ) is very close to zero; L represents the dynamic range of the pixel values (255 for 8-bit grayscale images) and k 1, k 2 < 1. In this paper, k 1 and k 2 are set to the default values 0.04 and L is set at 100.…”

“…It contains sensory and autonomic nerves located at the interface between the Bowman's layer and the basal epithelium. Corneal Confocal Microscopy (CCM) is a rapid non-invasive in vivo clinical technique for capturing images of the different corneal layers [2]. Morphological alterations in the epithelium, stroma and endothelium provide insights into a variety of corneal diseases [3,4] and assessment of the effects of wearing contact lenses [1], LASIK or PRK [5], fungal keratitis [6], corneal transplantation [7] or conditions such as keratoconus [8,9].…”