Jukka A. O. Moilanen

In vivo confocal microscopy after herpes keratitis.

Purpose. To describe the confocal microscopic findings, with special reference to corneal subbasal nerves, after herpes simplex virus (HSV) keratitis. Methods In this study, 16 HSV eyes and 14 contralateral eyes of 16 patients, diagnosed with unilateral HSV keratitis 1–12 months earlier by the presence of dendritic corneal ulceration or microbiologic confirmation, were examined by in vivo confocal microscopy for evaluation of corneal morphology. Results. Herpes simplex virus eyes: In 2 eyes the surface epithelial cells appeared large, and no abnormalities were observed in the basal epithelial cells. In 2 eyes subbasal nerve fiber bundles were completely absent, in 3 eyes there was a reduced number of long nerve fiber bundles, and in 11 eyes the subbasal nerve plexus appeared normal. In 10 corneas, highly reflective dendritic structures were found at the level of the basal epithelial cells. Frequently these structures were found in the vicinity of stromal fibrosis. Areas with increased abnormal extracellular matrix were found in 11 eyes. Stromal nerves were not visualized in all corneas, but appeared normal when observed. Contralateral eyes: No abnormalities were observed in the epithelium. All corneas presented with a normal subbasal nerve plexus, but in 2 eyes dendritic particles were observed. Three corneas presented with activated keratocytes and increased amounts of abnormal extracellular matrix. Conclusions. When visualized by confocal microscopy, the subbasal nerve plexus appears relatively unaffected in cases with resolved HSV keratitis. Unidentified dendritic structures, presumably Langerhans cells, are frequently seen at the level of the basal epithelium in corneas with a history of herpetic disease.

In vivo confocal microscopy for evaluation of wound healing following corneal refractive surgery

Understanding of corneal wound healing plays an important role, not only in management of corneal infections, but especially in refractive surgery. A better control of wound healing mechanisms might improve the results of such resculpturing techniques and help to avoid complications arising from these procedures. While studies have been focused in different aspects of corneal wound healing, our knowledge has increased greatly during the last years. Many problems associated with corneal healing also contribute to clinical pathology following corneal surgery. Understanding of such conditions has been augmented by the continuously developing corneal imaging techniques. We have used in vivo confocal microscopy (IVCM) for assessing corneas subjected to refractive surgery as well as corneas with common complications resulting from such procedures. IVCM has become a powerful tool for examining corneal cells, nerves, inflammations and infections. It allows information to be acquired repeatedly and at subbiomicroscopic levels that earlier had been obtainable only by invasive microscopic methods. Pre-examining corneas preoperatively by IVCM in order to reveal diseases or conditions in which elective refractive surgical procedures should not be undertaken or to select the ideal operation technique may help to avoid complications in the future. Measurement of the thickness of corneal sublayers or estimation of the thickness of a laser in situ keratomileusis flap or wound bed are other applications in which confocal microscopy may be valuable. In this article we attempt to describe the in vivo confocal findings of common refractive procedures and their complications, and discuss their biology in light of the existing knowledge on wound healing phenomena.

Multifactor effects and evidence of potential interaction between complement factor H Y402H and LOC387715 A69S in age-related macular degeneration.

Background Variants in the complement cascade genes and the LOC387715/HTRA1, have been widely reported to associate with age-related macular degeneration (AMD), the most common cause of visual impairment in industrialized countries. Methods/Principal Findings We investigated the association between the LOC387715 A69S and complement component C3 R102G risk alleles in the Finnish case-control material and found a significant association with both variants (OR 2.98, p = 3.75×10−9; non-AMD controls and OR 2.79, p = 2.78×10−19, blood donor controls and OR 1.83, p = 0.008; non-AMD controls and OR 1.39, p = 0.039; blood donor controls), respectively. Previously, we have shown a strong association between complement factor H (CFH) Y402H and AMD in the Finnish population. A carrier of at least one risk allele in each of the three susceptibility loci (LOC387715, C3, CFH) had an 18-fold risk of AMD when compared to a non-carrier homozygote in all three loci. A tentative gene-gene interaction between the two major AMD-associated loci, LOC387715 and CFH, was found in this study using a multiplicative (logistic regression) model, a synergy index (departure-from-additivity model) and the mutual information method (MI), suggesting that a common causative pathway may exist for these genes. Smoking (ever vs. never) exerted an extra risk for AMD, but somewhat surprisingly, only in connection with other factors such as sex and the C3 genotype. Population attributable risks (PAR) for the CFH, LOC387715 and C3 variants were 58.2%, 51.4% and 5.8%, respectively, the summary PAR for the three variants being 65.4%. Conclusions/Significance Evidence for gene-gene interaction between two major AMD associated loci CFH and LOC387715 was obtained using three methods, logistic regression, a synergy index and the mutual information (MI) index.

Corneal recovery after LASIK for high myopia A 2-year prospective confocal microscopic study

Aim: To quantify human corneal recovery after moderate to high myopic laser in situ keratomileusis (LASIK) in a 2-year prospective follow-up study. Methods: Fifteen eyes of 15 patients (mean refraction −10.1 (SD 2.4) D) were examined preoperatively and postoperatively at day 1, 5 days, 2 weeks, 1, 3 and 6 months and 2 years. Biomicroscopy, visual acuity and refraction were examined prior to imaging studies. An in vivo tandem scanning confocal microscope was used to obtain images from the central cornea. Subbasal nerve density was measured as the total length of nerve trunks in confocal image per mm2. Keratocyte density was calculated manually from stromal sublayers. The thickness of the altered keratocyte zone was measured on both sides of the LASIK interface. Results: At the end of the follow-up, all patients had a 20/20 BCVA, and nine of 15 patients were within ±0.5 D of the intended correction. The total corneal thickness remained unaltered, but epithelial hyperplasia was seen at 2 years. Keratocyte density in the anterior stroma and posterior to the flap interface showed a slight decrease during the follow-up. Subbasal nerve density decreased 82% in 5 days after LASIK. A gradual increase was observed from 2 weeks postoperatively, but even 2 years after the operation the nerve density was only 64% from the preoperative values. Conclusions: Subbasal nerve fibre density shows a gradual recovery throughout the follow-up. However, only three subjects showed totally regenerated subbasal nerve fibres at 2 years. This may correlate with the observed decrease in the density of the most anterior keratocytes. Corneal remodelling seemed to continue for at least 2 years.

Recovery of Corneal Sensitivity to Mechanical and Chemical Stimulation After Laser in situ Keratomileusis

PURPOSE To evaluate the time course of changes in corneal sensitivity to mechanical and chemical stimuli produced by laser in situ keratomileusis (LASIK) in humans. METHODS We performed a cross-sectional study of 17 LASIK-operated eyes (VisX S2, equipped with version 2.50-3.10 software) and 15 control eyes of 17 individuals to evaluate regeneration of corneal sensitivity after LASIK. Gas pulses of variable flow and compositions were applied to the cornea by a non-contact gas esthesiometer. Mechanical stimuli consisted of air puffs at flows from 0 to 200 ml/min. Chemical stimulation was made with gas pulses containing 0% to 80% CO2 in air at subthreshold flow. Mechanical and chemical thresholds and intensity-response curves for the evoked sensations were determined prior to surgery, and 7 to 9 days, 3 to 5 months, and 1.5 to 2.5 years after surgery. RESULTS Corneal sensitivity to mechanical stimulation was enhanced 7 to 9 days after surgery but subsequently dropped markedly and remained significantly below control levels 3 to 5 months after LASIK. Sensitivity to both mechanical and chemical types of stimuli was close to normal 2 years postoperatively. CONCLUSIONS Corneal sensitivity decreased immediately after LASIK but mechanical sensitivity showed a transient hyperesthesia 7 to 9 days afterward. Subsequently, a long-lasting and deep hypoesthesia to mechanical and chemical stimuli was observed. Gas esthesiometry revealed that disturbances of corneal sensation still exist at times when coarse mechanical sensitivity appeared to be normal.

In vivo confocal microscopy of Fleck dystrophy and pre-Descemet's membrane corneal dystrophy

Purpose. To assess the value of in vivo confocal microscopy (CM) in the diagnosis of Fleck dystrophy and pre-Descemets membrane corneal dystrophy. Methods. Case report of two patients. Standard slit-lamp and ophthalmic examination and in vivo CM were performed on both patients. The thickness of the cornea and the morphology of the corneal epithelium, stroma, endothelium, and subbasal nerves were evaluated by confocal microscopy. Results. Biomicroscopy revealed bilateral, fine, dust-, and flour-like opacities in the corneal stroma for the Fleck dystrophy patient. In the pre-Descemets membrane corneal dystrophy patient, biomicroscopy showed opacities larger than those in the first patient. Both patients were then examined by in vivo CM. Confocal microscopy of the Fleck dystrophy showed intracellular deposits throughout the stroma. In pre-Descemets membrane corneal dystrophy, however, these and the extracellular deposits were observed immediately anterior to Descemets membrane. The thicknesses of the corneas were 560 and 650 &mgr;m for Fleck and pre-Descemets membrane corneal dystrophy, respectively. The surface epithelium, subbasal nerves, and endothelium showed normal morphology in both patients. Conclusion. In vivo CM is a valuable tool in diagnosing rare corneal dystrophies when the final diagnosis is difficult to obtain with conventional methods.

A novel non-invasive, in vivo technique for the quantification of leukocyte rolling and extravasation at sites of inflammation in human patients

A novel non-invasive, in vivo technique for the quantification of leukocyte rolling and extravasation at sites of inflammation in human patients

Toxic carriers in pepper sprays may cause corneal erosion

We describe four patients who developed corneal erosion after an exposure to a pepper spray containing toxic carriers. Two of these patients were exposed to a pepper gas containing 5% oleoresin capsicum (OC) as an irritant and 92% trichlorethylene or unknown amount of dichloromethane as a carrier. One patient was exposed to a mock (containing 92% trichlorethylene as a carrier) training pepper gas without OC. The fourth patient was exposed to an unidentified Russian pepper gas spray. Two of the patients were examined by in vivo confocal microscopy to demonstrate the depth and quality of the stromal damage. To test the toxicity of the commercial tear spray, it was analyzed and test sprayed on a soft contact lens and into a plastic cup. Visual acuity was measured and the eyes were examined with a slit-lamp up to 5 months. Physical damage to a soft contact lens was visually acquired. All patients showed a long-lasting, deep corneal and conjuctival erosion, which resolved partly with medical therapy during the following weeks/months. Confocal microscopy revealed corneal nerve damage, and keratocyte activation reaching two-thirds of stroma for one patient. The spray caused serious damage to both the soft contact lens and the plastic cup. The safety of the commercially available pepper sprays should be assessed before marketing, and a list of acceptable ingredients created. The sprays should also have instructions on the use of the compound as well as on the first aid measures after the exposure. Solvents known to be toxic should not be used.

Keratocyte activation and inflammation in diffuse lamellar keratitis after formation of an epithelial defect.

Purpose: To examine the inflammatory reaction in acute or late‐onset post‐laser in situ keratomileusis (LASIK) diffuse lamellar keratitis (DLK) associated with an epithelial defect. Setting: Department of Ophthalmology, Helsinki University Central Hospital, Helsinki, Finland. Methods: Six consecutive LASIK patients presented with stage 2 to 3 unilateral DLK 1 to 4 days after formation of an epithelial detachment (intraoperatively or up to 19 months postoperatively). Five corneas of 5 DLK patients, 1 eye twice, were examined by corneal in vivo confocal microscopy 1 to 8 days after the appearance of the epithelial defect. Confocal microscopy of conjunctival venules was performed in 2 of 6 DLK patients to quantify leukocyte rolling and extravasation. Corneas of 5 patients and conjunctival venules of 4 patients who had uneventful LASIK served as controls. Results: Two of the 4 patients examined 0 to 1 day after the onset of DLK presented with small objects, presumably inflammatory cells (diameter 6.0 to 10.0 &mgr;m), in the LASIK flap interface. A third patient examined 1 day after the onset of DLK had larger objects (approximately 13.0 &mgr;m in diameter) in the interface. Three other cases (1 to 7 days after the onset of DLK) showed changes typical of keratocyte activation and altered extracellular matrix. All cases healed completely following treatment with steroids. Control LASIK subjects showed some keratocyte activation on day 5. Conclusions: Neither uneventful LASIK nor DLK induced an inflammatory reaction displaying leukocyte rolling in conjunctival venules or extravasation into the conjunctival stroma. Diffuse lamellar keratitis related to an epithelial defect does not always lead to the appearance of inflammatory cells in the flap interface. The corneal manifestations of epithelial defect‐related DLK may originate from sterile epithelial–stromal or inflammatory cell–stromal cell interactions, leading to alteration of the keratocyte phenotype.

Altered expression of matrix metalloproteinases and their tissue inhibitors as possible contributors to corneal droplet formation in climatic droplet keratopathy

Purpose:  Climatic droplet keratopathy (CDK) is an acquired corneal disease characterized by progressive scarring of the cornea. In several corneal diseases, matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation and molecular forms of MMP‐2, MMP‐9, MMP‐8 and MMP‐13 and their tissue inhibitors TIMP‐1 and TIMP‐2 in tear fluid of patients with CDK.