Yuichi Kaji

Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography

We present a case series of cornea and anterior segment disorders investigated by an office-based polarization-sensitive optical coherence tomography (PS-OCT). Blebs of glaucoma patients treated by trabeculectomy, and corneas of keratoconus and keratoplasty patients were measured by PS-OCT. Birefringence formations in trabeculectomy bleb were measured in 1 control eye and 3 eyes of trabeculectomy model rabbits. Polarization insensitive scattering OCT and the depth-resolved birefringence were measured simultaneously by PS-OCT. Abnormal birefringence was observed in keratoconus cases with advanced thinning and with a rupture of Descemet’s membrane. The graft-host interface of the keratoplasty case showed abnormal birefringence. The appearance of abnormal birefringence in the cornea was likely to be an indication of cross-linking of collagen fibrils. The measurement of rabbit showed abnormal birefringence in the scarring eyes. Wide regions of strong birefringence were observed in the eyes of trabeculectomy patients who had high intraocular pressure. Visualization of scarring in bleb by PS-OCT may be useful for the planning of secondary surgery. PS-OCT showed promising for the study and diagnosis diseases related to abnormal fibrous tissues of the cornea and anterior eye segment.

D-Amino acids in aged proteins: analysis and biological relevance.

Homochirality is essential for life. L-Amino acids are exclusively used as substrates for the polymerization and formation of peptides and proteins in living systems. However, d-amino acids, which are enantiomers of L-amino acids, were recently detected in various living organisms in the form of free D-amino acids and D-amino acid residues in peptides and proteins. In particular, D-aspartyl (Asp) residues have been detected in various proteins from diverse tissues of elderly individuals. Here, we describe three important aspects of our research: (i) a method for detecting D-β-Asp at specific sites in particular proteins, (ii) a likely spontaneous mechanism by which Asp residues in proteins invert and isomerize to the D-β-form with age under physiological conditions, (iii) a discussion of factors that favor such a reaction.

Collapse of homochirality of amino acids in proteins from various tissues during aging.

Prior to the emergence of life, it is believed that only L‐amino acids were selected for formation of proteins, and that D‐amino acids were eliminated on the primitive Earth. Whilst homochirality is essential for life, recently the occurrence of proteins containing D‐β‐aspartyl (Asp) residues from various tissues of elderly subjects has been reported. Here, we discuss the presence of D‐β‐Asp‐containing proteins in the lens, ciliary body, drusen, and sclera of the eye, skin, cardiac muscle, blood vessels of the lung, chief cells of the stomach, longitudinal and circular muscles of the stomach, and small and large intestines. Since the D‐β‐Asp residue occurs through a succinimide intermediate, this isomer may potentially be generated in proteins more easily than initially thought. UV Rays and oxidative stress can accelerate the formation of the D‐β‐Asp residue in proteins.

Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal eyes

Aims: To assess the retention and removal properties of a new viscous dispersive ophthalmic viscosurgical device (OVD), DisCoVisc, in comparison with those of cohesive (Provisc), dispersive (Viscoat), and viscoadaptive (Healon5) OVDs. Methods: In 20 porcine eyes, cataract surgery was simulated using one of the four OVDs which were stained with fluorescein for better visualisation. Three parameters were measured. Firstly, the presence/absence of OVDs in the chamber at the completion of phacoemulsification was recorded. Secondly, the time until the OVDs were completely removed from the anterior chamber using the phaco needle was measured. Thirdly, after intraocular lens (IOL) implantation, the time needed to completely remove the OVDs from the chamber with irrigation/aspiration tip was recorded. Results: At the completion of phacoemulsification, the OVDs retained in 0% (0/5) for Provisc, 80% (4/5) for Healon5, 100% (5/5) for DisCoVisc, and 100% (5/5) for Viscoat. The retention of OVDs during phacoemulsification was greatest with Viscoat followed by, in descending order, DisCoVisc, Healon5, and Provisc. The removal of OVDs after IOL implantation took longest with Viscoat followed by Healon5, DisCoVisc, and Provisc. Conclusion: The viscous dispersive DisCoVisc showed excellent retention during phacoemulsification, while its removal after IOL implantation was very easy. When compared with the viscoadaptive Healon5, DisCoVisc was retained better in the chamber and was easier to remove. These features of DisCoVisc should be highly advantageous when considering covering the entire cataract surgery procedure with a single OVD.

Successful treatment of endogenous Klebsiella pneumoniae endophthalmitis: a case report

BackgroundKlebsiella pneumoniae endophthalmitis is rare and despite immediate management, visual outcome is generally poor. We report a case of endogenous K. pneumoniae endophthalmitis that was treated successfully. Case An 80-year-old woman with a liver abscess was diagnosed at an early stage with endogenous K. pneumoniae endophthalmitis. She underwent par plana vitrectomy and lensectomy within 8xa0h after the onset of ocular symptoms. Secondary implantation of a sulcus-fixated intra-ocular lens (IOL) was performed 12xa0months later. Final visual acuity OS was 20/20. Conclusions The present case highlights the potential benefit of early and broad vitrectomy with lensectomy in the management of endogenous K. pneumoniae endophthalmitis.

Advanced glycation end product deposits in climatic droplet keratopathy

Background: Climatic droplet keratopathy (CDK), known as spheroid degeneration of the cornea, is one of the most frequent degenerative corneal disorders affecting visual function. However, the histochemical nature of the deposits seen in CDK is still unclear. Aim: To investigate the pathogenesis of CDK, we investigated the immunohistochemical localisation of advanced glycation end products (AGEs) in surgical specimens of CDK. Methods: Immunohistochemical localisation of Nε-(carboxymethyl)-l-lysine (CML), Nε-(carboxyethyl)-l-lysine (CEL), pyrraline, pentosidine and imidazolone was examined in three corneas with CDK, six corneas with bullous keratopathy and three corneas without any corneal diseases. Results: In all the specimens with CDK, immunoreactivity was strong in CML, moderate in pyrraline and pentosidine, and weak in imidazolone. Immunoreactivity was absent in CEL. In contrast, no immunoreactivity to CML, pyrraline, pentosidine, imidazolone or CEL was detected in corneas with bullous keratopathy, or in corneas without any corneal diseases. Conclusions: CDK is caused by an aggregation of AGE-modified proteins. The result is consistent with etiological findings that ultraviolet irradiation and ageing, both of which are accelerators of AGE formation, are closely related to the development of CDK.

Destruction of amyloid fibrils of keratoepithelin peptides by laser irradiation coupled with amyloid-specific thioflavin T

Mutations in keratoepithelin are associated with blinding ocular diseases, including lattice corneal dystrophy type 1 and granular corneal dystrophy type 2. These diseases are characterized by deposits of amyloid fibrils and/or granular non-amyloid aggregates in the cornea. Removing the deposits in the cornea is important for treatment. Previously, we reported the destruction of amyloid fibrils of β2-microglobulin K3 fragments and amyloid β by laser irradiation coupled with the binding of an amyloid-specific thioflavin T. Here, we studied the effects of this combination on the amyloid fibrils of two 22-residue fragments of keratoepithelin. The direct observation of individual amyloid fibrils was performed in real time using total internal reflection fluorescence microscopy. Both types of amyloid fibrils were broken up by the laser irradiation, dependent on the laser power. The results suggest the laser-induced destruction of amyloid fibrils to be a useful strategy for the treatment of these corneal dystrophies.

Combined micro and macro additive manufacturing of a swirling flow coaxial phacoemulsifier sleeve with internal micro-vanes

Microstereolithography (µSL) technology can fabricate complex, three-dimensional (3D) microstructures, although µSL has difficulty producing macrostructures with micro-scale features. There are potentially many applications where 3D micro-features can benefit the overall function of the macrostructure. One such application involves a medical device called a coaxial phacoemulsifier where the tip of the phacoemulsifier is inserted into the eye through a relatively small incision and used to break the lens apart while removing the lens pieces and associated fluid from the eye through a small tube. In order to maintain the eye at a constant pressure, the phacoemulsifier also includes an irrigation solution that is injected into the eye during the procedure through a coaxial sleeve. It has been reported, however, that the impinging flow from the irrigation solution on the corneal endothelial cells in the inner eye can damage these cells during the procedure. As a result, a method for reducing the impinging flow velocities and the resulting shear stresses on the endothelial cells during this procedure was explored, including the design and development of a complex, 3D micro-vane within the sleeve. The micro-vane introduces swirl into the irrigation solution, producing a flow with rapidly dissipating flow velocities. Fabrication of the sleeve and fitting could not be accomplished using µSL alone, and thus, a two-part design was accomplished where a sleeve with the micro-vane was fabricated with µSL and a threaded fitting used to attach the sleeve to the phacoemulsifier was fabricated using an Objet Eden 333 rapid prototyping machine. The new combined device was tested within a water container using particle image velocimetry, and the results showed successful swirling flow with an ejection of the irrigation fluid through the micro-vane in three different radial directions corresponding to the three micro-vanes. As expected, the sleeve produced a swirling flow with rapidly dissipating streamwise flow velocities where the maximum measured streamwise flow velocities using the micro-vane were lower than those without the micro-vane by 2xa0mm from the tip where they remained at ∼70% of those produced by the conventional sleeve as the flow continued to develop. It is believed that this new device will reduce damage to endothelial cells during cataract surgery and significantly improve patient outcomes from this procedure. This unique application demonstrates the utility of combining µSL with a macro rapid prototyping technology for fabricating a real macro-scale device with functional, 3D micro-scale features that would be difficult and costly to fabricate using alternative manufacturing methods.

Toxicities and pharmacokinetics of subconjunctival injection of liposomal amphotericin B.

IntroductionThe toxicity of conventional formulations of amphotericin B deoxycholate (AmBDOC) limits its clinical applications. To reduce the toxicity of AmBDOC, lipid formulations of amphotericin B (AmB) have been developed and clinically applied. In the present study, we evaluated the ocular toxicity and pharmacokinetics of subconjunctival injection of liposomal AmB.Materials and methodsSubconjunctival injection of either AmBDOC (containing 1.5xa0mg of AmB and 1.2xa0mg of deoxycholate), deoxycholate (1.2xa0mg), or liposomal amphotericin B (L-AmB) (containing 1.5xa0mg of AmB and lipids) was given to white New Zealand rabbits. After 24xa0hours, toxicities of the drugs were evaluated by slit lamp and histologically. To evaluate the pharmacokinetics of subconjunctival injection of L-AmB, the concentration of the drug in the cornea was evaluated at 4, 12, 24, and 48xa0hours after subconjunctival injection of L-AmB, with or without corneal epithelial removal.ResultsSubconjunctival injection of AmBDOC or deoxycholate alone induced severe corneal and conjunctival edema, with necrosis and infiltration of inflammatory cells. In contrast, subconjunctival injection of L-AmB induced only mild inflammation near the injection site. The concentration of AmB injected in eyes with intact corneal epithelium was 4.93–2.49, 0.63–0.31, 0.15–0.07xa0μg/g at 4, 12, and 24xa0hours respectively after the injection of L-AmB. When injected in eyes after corneal epithelial removal, the concentration of AmB was 19.7–9.87, 2.49–1.25, and 1.25–0.63xa0μg/g at 4, 12, and 24xa0hours after injection respectivelyConclusionsSubconjunctival injection of L-AmB has reduced ocular toxicities and gives satisfactory concentrations in corneal stroma compared with conventional AmBDOC. Subconjunctival injection of L-AmB will be a choice of treatment for mycotic keratitis.

Immunohistochemical localization of advanced glycation end products in pinguecula.

BackgroundAdvanced glycation end products (AGEs) are known to be deposited in the target organ of ageing. In addition, the deposition of AGEs accelerate the process of ageing. We investigated the immunohistochemical localization of AGEs in pinguecula, one of the ocular changes related with ageing process.MethodsSurgical specimens of conjunctiva with or without pinguecula were prepared from nine patients, respectively. Immunohistochemical localization of AGEs was investigated using monoclonal antibodies to