Auguste G.-Y. Chiou

Interface inflammation after laser in situ keratomileusis: Sands of the Sahara syndrome

Purpose: To determine the source of the interface debris that causes the interface inflammation known as “sands of the Sahara” after laser in situ keratomileusis (LASIK). Setting: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans, USA. Methods: A microkeratome (Automated Corneal Shaper) was used to make a LASIK flap in 8 eyes of 4 rabbits. In 4 eyes, the blade was used directly from the sterile pack; in the contralateral 4 eyes, the blade was cleaned prior to use. In vivo confocal microscopy of the corneas was performed 1 day after surgery. An unused, cleaned blade and an unused, uncleaned blade, as well as blades used in the rabbit eyes, were examined by scanning electron microscopy. Methods: Confocal microscopy revealed numerous fragments of debris surrounded by inflammatory cells in the LASIK flap interfaces created by blades taken directly from the sterile package. Interfaces created by the cleaned blades showed only rare, scattered bits of debris. Scanning electron microscopy of the unused blades showed debris on the uncleaned blade removed directly from the sterile package. Conclusion: Post‐LASIK interface inflammation may be caused by debris on the microkeratome blade, although other sources are possible. The interface debris and inflammation can be reduced or eliminated by cleaning the microkeratome blade before use.

Confocal microscopy in cornea guttata and Fuchs' endothelial dystrophy

AIMS To report the appearances of cornea guttata and Fuchs’ endothelial dystrophy from white light confocal microscopy. METHODS Seven eyes of four consecutive patients with cornea guttata were prospectively examined. Of the seven eyes, three also had corneal oedema (Fuchs’ dystrophy). In vivo white light tandem scanning confocal microscopy was performed in all eyes. Results were compared with non-contact specular microscopy. RESULTS Specular microscopy was precluded by corneal oedema in one eye. In the remaining six eyes, it demonstrated typical changes including pleomorphism, polymegathism, and the presence of guttae appearing as dark bodies, some with a central bright reflex. In all seven eyes, confocal microscopy revealed the presence of round hyporeflective images with an occasional central highlight at the level of the endothelium. Changes in cell morphology and size were readily appreciated. CONCLUSION By comparison with specular microscopy, the hyporeflective images with an occasional central highlight seen on confocal microscopy are consistent with the presence of guttae. Confocal microscopy may confirm the diagnosis of cornea guttata and Fuchs’ endothelial dystrophy by demonstrating the presence of guttae. This technique is especially valuable in cases of corneal oedema, where specular microscopy may fail to visualise the endothelium. However, specular microscopy should remain the method of choice to evaluate the endothelium, principally because it is easier to use.

Differential diagnosis of linear corneal images on confocal microscopy.

PURPOSE This study aimed to detect corneal conditions presenting with linear images on white light confocal microscopy and to analyze their distinguishing characteristics. METHODS In 1996 and 1997, 153 eyes of 110 patients with various corneal conditions were examined. In vivo examination of the cornea was performed by using a white-light tandem scanning confocal microscope. Images were captured by using a video camera and stored on S-VHS video tapes. In this retrospective study, patient charts and confocal microscopic video records were reviewed. Conditions with linear images were looked for, and the images were analyzed and compared. RESULTS The only structures presenting as linear images on confocal microscopy in normal subjects consisted of corneal nerves. The following pathologic conditions also had linear images on confocal microscopy: corneal vascularization, mycotic keratitis, lattice corneal dystrophy, and posterior polymorphous dystrophy. Each condition could be identified based on its reflectivity, delineation, size, branching pattern, and location in the cornea. CONCLUSION Different corneal conditions present with linear images on confocal microscopy. Correct identification is critical to avoid misdiagnosis.

Confocal microscopy in the iridocorneal endothelial syndrome.

AIMS To report the appearances of iridocorneal endothelial (ICE) syndrome from real time, white light confocal microscopy. METHODS Three consecutive patients, each with ICE syndrome, were examined prospectively. Corneal specular and confocal microscopic examinations were performed in all three patients. In the first patient, a penetrating keratoplasty was performed and the cornea was examined by light and scanning electron microscopy. No surgery was performed in the remaining two patients. RESULTS In the first patient corneal oedema prevented endothelial specular microscopy. Confocal microscopy performed before penetrating keratoplasty successfully revealed abnormal epithelial-like endothelial cells. Histological examinations of the cornea following penetrating keratoplasty revealed the presence of multilayered endothelial cells with epithelial features (microvilli). In the remaining two patients, specular microscopy showed the presence of ICE cells with typical dark/light reversal. Confocal microscopy demonstrated groups of endothelial cells with epitheloid appearances. In all three patients, the contralateral endothelial appearance was normal by specular and confocal microscopy, except for moderate endothelial polymegathism in one patient. Epithelial-like endothelial cells were characterised by prominent nuclei on confocal microscopy. CONCLUSIONS The application of confocal microscopy indicates that the ICE syndrome is characterised by epitheloid changes in the endothelium. Confocal microscopy may be used to diagnose the ICE syndrome by demonstrating epithelial-like endothelial cells with hyperreflective nuclei. This technique is especially of value in cases of corneal oedema, since specular microscopy may fail to image the endothelium in such cases.

Current applications of clinical confocal microscopy.

Purpose of review Confocal microscopys role within ophthalmology has been evolving since the introduction of this technology in 1955. The purpose of this review is to describe the confocal microscope and illustrate its recent ophthalmic applications. Recent findings Numerous investigators have used confocal microscopy to research ophthalmic disease and to find new diagnostic applications. This review will describe the development and uses of this technology. The cornea was the first ophthalmic tissue to be imaged due to its transparency, although, tissues, such as conjunctiva, are now being studied. This article will review normal confocal corneal appearance and discuss a wide range of recent applications that include corneal infections, dystrophies and disease. Furthermore, this article will discuss recent developments in refractive surgery, ocular surgery and various miscellaneous discoveries. Summary Confocal microscopy is developing into a powerful research and diagnostic tool in ophthalmology. The future uses of this novel technology will evolve and is increasingly becoming a vital tool in the ophthalmologists armamentarium.

Confocal microscopy in posterior polymorphous corneal dystrophy

Purpose: To report the distinguishing characteristics of posterior polymorphous corneal dystrophy (PPMD) using confocal microscopy. Material and Methods: Two consecutive patients with PPMD were prospectively examined using a white-light tandem scanning confocal microscope with a 24×/0.60 contact objective. Results: At the level of Descement’s membrane, roundish hyporeflective images were found in 1 patient. In the other patient, hyporeflective bands were detected. In both patients, patchy hyperreflective areas were identified. Conclusion: Confocal microscopy may allow diagnosis of PPMD by demonstrating the alterations in Descement’s membrane. This technique is especially valuable in cases of endothelial decompensation, where slit-lamp and specular microscopy may fail to demonstrate changes in Descement’s membrane.

Characterization of Fibrous Retrocorneal Membrane by Confocal Microscopy

PURPOSE To study the appearance of a fibrous retrocorneal membrane as seen by confocal microscopy. METHODS A 67-year-old white woman with a history of multiple ocular surgeries, including repeated penetrating keratoplasties for aphakic bullous keratopathy, developed a retrocorneal membrane in the right eye. The membrane was first noticed 3 years after the last corneal transplant and remained stable subsequently. The patient was examined by in vivo white light tandem-scanning confocal microscopy. RESULTS At the level of the retrocorneal membrane, confocal microscopy disclosed the presence of a hyperreflective fibrous-appearing layer. Normal endothelial cells could not be found. Anterior to the hyperreflective layer, activated keratocytes were identified. CONCLUSION Confocal microscopy may allow noninvasive diagnosis of fibrous retrocorneal membrane. Additionally, our data suggest that the posterior keratocytes might play a role in the production and deposition of fibrous tissue.

Characterization of epithelial downgrowth by confocal microscopy

A 43-year-old white woman with a history of multiple ocular surgeries, including 4 penetrating keratoplasties, developed a concentric retrocorneal membrane at the graft periphery in the right eye. A white-light, tandem, scanning confocal microscope using a 24x/0.60 contact objective was used to examine the right eye in vivo. At the endothelial layer, confocal microscopic images similar to corneal epithelial cells were detected at the graft periphery. Unlike normal endothelial cells, the imaged cells demonstrated easily recognizable nuclei.

RECURRENT MEESMANN'S CORNEAL EPITHELIAL DYSTROPHY AFTER PENETRATING KERATOPLASTY

Purpose To characterize the histopathology of recurrent Meesmanns corneal epithelial dystrophy after penetrating keratoplasty. Methods Postmortem examination by light and electron microscopy of the eyes of an 84-year-old patient with Meesmanns dystrophy who underwent a penetrating kerato-plasty in the right eye at age 74 years and a lamellar kerato-plasty in the left eye at age 51 years. Results In the right eye, the characteristic features of Meesmanns dystrophy were demonstrated in both the donor and recipient corneas. The pathologic findings were limited to the corneal epithelium and included increased thickness, architectural disorganization, loss of cell polarity, increased amounts of intracellular glycogen, presence of intraepithelial microcysts containing degenerated cells, and in some cells, the presence of an electron-dense fibrillogranular material associated with disrupted cytoplasmic filaments. In the left eye, the corneal findings were consistent with but not specific for Meesmanns dystrophy. These included architectural disorganization, loss of cell polarity, presence of intraepithelial microcysts, and irregular thickening of the basement membrane in the donor cornea. Conclusion Meesmanns corneal epithelial dystrophy is demonstrated to recur after penetrating keratoplasty. This finding suggests that the abnormalities that lead to the disease are localized to the corneal epithelial cells and not in the stroma, as previously proposed.

Pseudophakic ametropia managed with a phakic posterior chamber intraocular lens.

&NA; We report the use of a phakic posterior chamber intraocular lens (IOL) to correct pseudophakic ametropia. Two eyes of 2 patients developed ametropia after unilateral phacoemulsification and IOL implantation. The manifest refraction was −6.00 −0.50 × 50 in the first patient and +4.50 −1.00 × 15 in the second. Both patients were bothered by the induced anisometropia and had posterior chamber phakic IOL implantation in the pseudophakic eye. Postoperatively, uncorrected visual acuity improved from 20/400 to 20/30 in the first patient and from 20/200 to 20/40 in the second patient. The manifest refraction was −0.50 −0.75 × 55 and +1.50 −1.50 × 30, respectively. No complications were noted. Implantation of a phakic posterior chamber IOL may be an alternative to currently available methods of managing pseudophakic ametropia.