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Biomedical subjects

Yuichi Kaji

Publications and source records attributed to Yuichi Kaji.

At least 19 recordsLinked to original sources
PubMed2006

Inadvertent insertion of an opposite-power intraocular lens.

An 82-year-old woman with age-related cataract and high myopia had uneventful phacoemulsification and intraocular lens (IOL) implantation. Preoperative visual acuity was 20/60 with -16.00 -3.00 x 70 and axial length was 29.29 mm. An IOL (MA60MA, Alcon) of +5.0 diopters (D) was selected with target refraction of -1.5 D. The next day, visual acuity was 20/15 with +5.50 -2.00 x 60. It was found that an IOL of -5.0 D was inadvertently inserted instead of +5.0 D because of an identical package appearance of the opposite-diopter IOLs except for a small negative sign before the diopter label. The -5.0 D IOL was surgically replaced with +5.0 D IOL, and visual acuity became 20/15 with -0.50 -2.00 x 70. When selecting an IOL for highly myopic patients, attention should be paid to the extreme resemblance of the package of opposite-diopter IOLs.

Aged, 80 and over↗
PubMed2006

An endothelin type A receptor antagonist reverses upregulated VEGF and ICAM-1 levels in streptozotocin-induced diabetic rat retina.

Diabetic retinopathy, a cause of blindness, is often associated with the upregulation of vascular endothelial growth factor (VEGF) in the retina. Recently, leukocyte adhesion (leukostasis) is claimed for the occlusion of retinal capillary vascularity, which ultimately assists in the progression of diabetic retinopathy. In addition, intercellular adhesion molecule-1 (ICAM-1), a representative factor for leukostasis, is increased in diabetic retina. Endothelin (ET)-1, a potent vasoconstrictor peptide, is closely linked to the pathogenesis of diabetic retinopathy. Different therapeutic interventions concerning VEGF have already been proposed to prevent diabetic retinopathy. However, no study has yet reported concerning the effects of ET-1 receptor antagonist on the upregulated VEGF and ICAM-1 in morphologically intact diabetic retina. The current study investigated the effect of ET(A) receptor antagonist (TA-0201; 1 mg kg(-1) day(-1)) on the expressions of VEGF and ICAM-1 in rat diabetic retina. Diabetes was induced by intraperitoneal injection of streptozotocin (70 mg/kg) in Sprague-Dawley rats, whereas control rats (Cont) received only citrate buffer. After 1 week, the streptozotocin-administered rats were randomly divided into two groups: ET(A) receptor antagonist-treated group (DM+TA-0201) and saline-treated group (DM+vehicle). After the treatment for 4 weeks, the retina was removed from the eyeball. In DM+vehicle group, the VEGF expression of retina was significantly increased (33.5 pg/mg) in comparison with that in the Cont group (25.1 pg/mg), and the upregulation of VEGF was reversed in DM+TA-0201 group (26.9 pg/mg), a phenomenon consistent with the change in VEGF mRNA levels. The expression of retinal ICAM-1 was increased in DM+vehicle group (55.1 pg/mg) compared with Cont group (43.8 pg/mg), and ET antagonism completely blocked this increase (43.8 pg/mg). Moreover, an increased leukostasis by 3.3-fold in DM+vehicle retina was returned to the control level by ET antagonism. In the current study, there was no obvious retinal morphological alteration from both the hematoxylin and eosin staining and the FITC-dextran angiography. Thus, ET(A) receptor antagonist might be useful in preventing the progression of diabetic retinopathy, as evidenced by suppressing the increase in VEGF and ICAM-1 levels as well as leukostasis in morphologically intact diabetic retina.

Animals↗
PubMed2006

Optical quality of the cornea after overnight orthokeratology.

PURPOSE: To review changes in the optical quality of the cornea induced by overnight orthokeratology for myopia. METHODS: Sixty-four eyes of 39 patients who underwent overnight orthokeratology for myopia were prospectively examined. Inclusion criteria were uncorrected visual acuity of 20/20 or better after treatment and a minimum follow-up of 3 months. To quantitatively assess changes in corneal regular and irregular astigmatism, videokeratography data were decomposed into spherical component, regular astigmatism, asymmetry, and higher-order irregularity using Fourier analysis. In addition, corneal wavefront aberrations were calculated by expanding anterior corneal height data from videokeratography into a set of orthogonal Zernike polynomials. RESULTS: Although orthokeratology significantly reduced manifest refraction and improved uncorrected visual acuity, the asymmetry component, which is one of the features of irregular astigmatism, increased significantly from 0.35 +/- 0.22 to 0.64 +/- 0.40 D after treatment (P < 0.0001, paired t test). The increases in the asymmetry component significantly correlated with the amount of myopic correction (Pearson correlation coefficient, R = 0.40, P = 0.0009). Furthermore, the root-mean-square of third-order (coma-like) and fourth-order (spherical-like) aberrations significantly increased after orthokeratology (P < 0.0001, paired t test), and these increases showed significant positive correlations with the amount of myopic correction (Pearson correlation coefficient, R = 0.452, P = 0.0001 and R = 0.381, P = 0.0017, respectively). CONCLUSION: Corneal irregular astigmatism and higher-order aberrations significantly increased even in clinically successful orthokeratology, and the increases correlated with the magnitude of myopic correction. A large myopic correction by orthokeratology should be avoided to not decrease corneal optical quality.

Adolescent↗
PubMed2006

Influence of pupil diameter on the relation between ocular higher-order aberration and contrast sensitivity after laser in situ keratomileusis.

PURPOSE: To investigate the influence of pupil diameter on the relation between induced changes in ocular higher-order wavefront aberrations and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. METHODS: In 215 eyes of 117 patients (age, 33.2 +/- 8.3 years) undergoing LASIK for myopia of -1.25 to -13.5 D (-5.28 +/- 2.55 D), ocular wavefront aberrations and contrast sensitivity function were determined before and 1 month after surgery. Preoperative photopic pupil diameter was measured with a digital camera. Ocular higher-order aberrations were measured for a 4-mm pupil with a Hartmann-Shack wavefront analyzer. The root-mean-square (RMS) of the third- and fourth-order Zernike coefficients was used to represent coma- and spherical-like aberration, respectively. From the contrast-sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS: One hundred five eyes had a photopic pupil diameter of 4 mm or larger, and the remaining 110 had a photopic pupil diameter smaller than 4 mm. There were no statistically significant differences in the background clinical data between these two groups. In the eyes with a photopic pupil diameter of 4 mm or larger, the changes in third-order comalike aberrations did not correlate with the changes in AULCSF (Pearson correlation coefficient, r = -0.037, P = 0.723) and 10% low-contrast visual acuity (r = 0.125, P = 0.224), but fourth-order spherical-like aberrations correlated significantly with the changes in AULCSF (r = -0.229, P = 0.024) and 10% low-contrast visual acuity (r = 0.221, P = 0.038). In the eyes with photopic pupil size smaller than 4 mm, there were significant correlations between the changes in comalike aberrations and the changes in AULCSF (r = -0.487, P < 0.001) and 10% low-contrast visual acuity (r = 0.310, P = 0.003), but spherical-like aberrations showed no correlation with the changes in AULCSF (r = -0.078, P = 0.485) and 10% low-contrast visual acuity (r = 0.208, P = 0.158). CONCLUSIONS: In eyes with larger photopic pupil diameter, increases in spherical-like aberration dominantly affect contrast sensitivity, whereas in eyes with smaller pupil size, changes in coma-like aberration exert greater influence on visual performance.

Adolescent↗
PubMed2006

A model of retinal ischemia-reperfusion injury in rats by subconjunctival injection of endothelin-1.

The retinal ischemia-reperfusion model is used in the study of transient ischemia-related diseases, such as central retinal artery occlusion, angle-closure glaucoma, and others. There are two methods for experimentally producing an ischemia-reperfusion model in the rat retina: (i) the intraocular pressure is greatly raised by increasing the height of the infusion bottle connected with the needle in the anterior chamber; or (ii) the blood vessel that accompanies the optic nerve in retina is ligated. However, each method has some drawbacks. For example, in the first method, the needle must be fixed in the anterior chamber for 1 hr, thus, the technique is not stable and mechanical damage to ocular structures sometimes occurs. In the second method, because of the unavoidable involvement of the optic nerve, damage to the nerve induces retinal changes unrelated to ischemia. In this study, we injected endothelin (ET)-1 under the conjunctiva of the eyeball (subconjunctival injection), and evaluated whether a retinal ischemia-reperfusion model could be generated by this method, simply and noninvasively. We injected 4 x 10(-5) M ET-1 solution into the right eye of the rat and injected a control vehicle (artificial tears) into the left eye. From 5-60 mins after the injection, 50 mg/ml fluorescein isothiocyanate (FITC)-dextran was injected to the left ventricle of heart. Then, the retina was removed and flat mounted. We compared the perfusion conditions of the FITC-dextran to each retina in the right and left eye. There was a complete perfusion of FITC-dextran in the retinal main artery, vein, and the capillary vessels in all of the control eyes. However, perfusion could not be completely observed in the ET-1 injected eye from 5-35 mins after injection; afterwards, the flow was returned. This method of subconjunctival injection of ET-1 is, thus, a feasible technical option for producing a retinal ischemia-reperfusion model in rat.

Animals↗
PubMed2005

Immunohistochemical localization of advanced glycation end products in pinguecula.

BACKGROUND: Advanced 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. METHODS: Surgical specimens of conjunctiva with or without pinguecula were prepared from nine patients, respectively. Immunohistochemical localization of AGEs was investigated using monoclonal antibodies to N(epsilon)-(carboxymethyl)lysine, pentosidine, imidazolone, and pyrraline. RESULTS: Moderate to strong immunoreactivities to AGEs were detected in the subepithelial amorphous deposits of all the surgical specimens with pinguecula. In contrast, no or weak immunoreactivities to AGEs were detected in the surgical specimens without pinguecula. CONCLUSIONS: Pinguecula is an aggregation of AGEs-modified proteins. The presence of pinguecula would be an index of local irradiation of ultraviolet rays and decreased antioxidant activities.

Adult↗
PubMed2005

Ocular higher-order wavefront aberration caused by major tilting of intraocular lens.

PURPOSE: To report a patient with a significant amount of ocular coma-like aberration that was caused by the tilting of an intraocular lens (IOL) who was treated successfully by IOL repositioning surgical procedure. DESIGN: Interventional case report. METHODS: At the Department of Ophthalmology, University of Tsukuba, a 52-year-old man complained of unclear and distorted vision in his left pseudophakic eye. The tilt and decentration of IOL were measured with the Scheimpflug videophotography system. Ocular and corneal wavefront aberrations were measured with the Hartmann-Schack aberrometer. RESULTS: The tilting angle was 28.87 degrees, and decentration was 1.78 mm. The ocular coma-like aberration was increased remarkably to 0.451 microm at 4.0 mm aperture diameter, and the simulated retinal image of a Landolt ring was blurred substantially. Ocular spheric-like, corneal coma-like, and corneal spheric-like aberrations were not increased. The IOL repositioning surgery significantly improved the IOL tilt, which resulted in the reduction of ocular coma-like aberration, recovery of simulated retinal image, and resolution of the patient's complaints. CONCLUSION: Major IOL tilting induces a large amount of ocular coma-like aberration, which deteriorates the patient's quality of vision.

Astigmatism↗
PubMed2005

Clinical application of 11-deoxycortisol in visualizing prolapsed vitreous body after posterior capsule rupture in cataract surgery.

PURPOSE: To evaluate the clinical usefulness of 11-deoxycortisol, a precursor of cortisol in steroid metabolism, in visualizing the vitreous body in the anterior chamber after posterior capsule rupture during cataract surgery. SETTING: Department of Ophthalmology, Tsukuba University Hospital, Ibaraki, Japan. METHODS: Eight eyes had anterior vitrectomy during cataract surgery using this new technique. A suspension of 11-deoxycortisol was prepared by dilution in balanced salt solution without preservatives or emulsifying agents. After a posterior capsule rupture, the suspension was injected into the anterior chamber. The visual and anatomical outcomes of surgery were evaluated during a follow-up of 7 to 9 months. RESULTS: After the 11-deoxycortisol injection, the vitreous body that had prolapsed through the torn posterior capsule, with white particles entrapped on its surface, became clearly visible. Complete removal of the prolapsed vitreous body was achieved easily and safely using an anterior vitrectomy system. No postoperative complications related to the use of 11-deoxycortisol were observed. CONCLUSION: Injection of 11-deoxycortisol helped visualize the vitreous body in the anterior chamber after posterior capsule rupture. The technique minimized intraoperative and postoperative complications related to posterior capsule rupture and vitreous loss during cataract surgery [corrected]

Aged↗
PubMed2005

Visual acuity measurements using Fourier series harmonic analysis of videokeratography data in eyes after penetrating keratoplasty.

PURPOSE: Fourier harmonic analysis can decompose videokeratography data into spherical power, regular astigmatism, and irregular astigmatism (asymmetry and higher-order irregularity). The aim of this study was to evaluate whether determination of cylinder power by Fourier analysis facilitates measurements of visual acuity and refraction in eyes after penetrating keratoplasty. DESIGN: Cross-sectional study. PARTICIPANTS: Sixty-six eyes of 56 subjects who had undergone penetrating keratoplasty. METHODS: Spectacle-corrected visual acuity was measured in 2 ways: by the conventional and the Fourier methods. In the conventional method, the refraction was determined subjectively by reference to the measurement results of the autokeratometer and autorefractometer. In the Fourier method, the magnitude and axis of regular astigmatism were calculated by Fourier analysis of the videokeratography data, and spherical lenses were adjusted until best spectacle-corrected visual acuity was attained. MAIN OUTCOME MEASURES: Logarithm of the minimum angle of resolution (logMAR) visual acuity and refraction used for correction. RESULTS: The spectacle-corrected visual acuity obtained with the Fourier method (logMAR, 0.23+/-0.32; Snellen equivalent, 20/34) was significantly better than that attained with the conventional method (logMAR, 0.31+/-0.29; Snellen equivalent, 20/41; P<0.001, paired t test). The cylinder power used for spectacle-corrected visual acuity measurements was significantly lower with the Fourier method (-2.41+/-1.26 diopters [D]) than with the conventional method (-3.53+/-1.64 D; P<0.001). The spherical equivalent at the final refraction was not different between groups (P = 0.207). CONCLUSIONS: Fourier analysis of videokeratography data significantly facilitates determination of refraction and measurement of best spectacle-corrected visual acuity in eyes with corneal irregular astigmatism, such as eyes that have undergone penetrating keratoplasty.

Adolescent↗
PubMed2005

Ultraviolet transmittance of human limbal epithelial cells cultured on human amniotic membranes.

PURPOSE: To evaluate ultraviolet (UV) A and B transmittance by human limbal epithelial cells cultured on human amniotic membranes. METHODS: Human limbal epithelial cells were taken from the limbus of donor corneas and were cultured on human amniotic membranes with inactivated 3T3 fibroblasts for 2 to 4 weeks. Then, the cultured cells were examined histologically. Next, cells from different culture periods were irradiated with UV-A (365 nm) or UV-B (302 nm) at energy levels ranging from 50 to 800 microW/cm2, and UV transmittance was measured with a UV light meter. RESULTS: Histological examination revealed a monolayer of corneal epithelial cells on the amniotic membrane after 2 weeks of culture, and a layer of 3-4 cells was formed after 4 weeks. Transmittance of UV-A and UV-B was highest by the amniotic membrane alone, followed in decreasing order by limbal epithelial cells cultured on amniotic membranes for 2 weeks, 3 weeks, and 4 weeks. CONCLUSIONS: These results indicate that UV absorbance increases in proportion to the number of limbal epithelial cell layers in cultures on amniotic membranes. Limbal epithelial cells may need to be cultured until 3-4 layers are formed in order to prevent ocular damage by UV light after transplantation.

3T3 Cells↗
PubMed2005

Toxicological evaluation of micafungin ophthalmic solution in rabbit eyes.

There have been no reports of the topical application of micafungin to the eye. The aim of this study was to evaluate the safety of topical instillation of 0.1% micafungin ophthalmic solution in rabbit eyes. In New Zealand white rabbits (n = 6), 50 microL of 0.1% micafungin solution was topically instilled to 1 eye, and 50 microL of sterile saline was applied to the other eye. Both eyedrops were administered hourly from 7 A.M. for 7 days. Measurements were conducted on corneal thickness, intraocular pressure, endothelial cell density, and lactate dehydrogenase (LDH) activity of tear samples. The eyes were examined slit-lamp biomicroscopically and histopathologically. Topical micafungin application for 1 week did not induce any changes in intraocular pressure, endothelial cell density, and tear LDH. Corneal thickness after instillation was slightly, but significantly, smaller in the micafungin group than in the control group (P = 0.0156, paired t test), but this difference disappeared within 24 hours after the final instillation. Biomicroscopy and histopathology revealed no significant toxic influence of micafungin application on the cornea. Topical instillation of micafungin solution had no apparent toxicity to the cornea. These results warrant future studies on the efficacy of micafungin ophthalmic solution against corneal fungal infection.

Animals↗
PubMed2005

Effect of shear stress on attachment of corneal endothelial cells in association with corneal endothelial cell loss after laser iridotomy.

PURPOSE: Laser iridotomy often causes bullous keratopathy; however, the mechanism is unclear. We investigated whether changes in aqueous humor hydrodynamics after laser iridotomy have any role in corneal endothelial cell loss. MATERIALS AND METHODS: Porcine corneal endothelial cells were plated onto glass slides. Following 1 or 3 hours for adhesion, the endothelial cells were exposed to shear stresses (0.1-10 dyne/cm) for 15 minutes, and the number of detached cells was counted. In addition, the pressure and shear stress on corneal endothelial layer were calculated in a virtual model of laser iridotomy. RESULTS: The number of detached corneal endothelial cells increased with shear stresses in a dose-dependent manner. Significant increase of rate of detached corneal endothelial cells was observed at >0.3 dyne/cm after 1-hour attachment and at 1 dyne/cm after 3-hour attachment. The maximum pressure on corneal endothelial layer was 0.007 mm Hg, which is negligible compared with intraocular pressure. However, the maximum shear stress on the corneal endothelial layer could be> dyne/cm in some conditions of laser iridotomy. CONCLUSIONS: The resistance of corneal endothelial cell loss to shear stress is time dependent. Shear stress could be a cause of corneal endothelial cell loss in some conditions of laser iridotomy.

Animals↗
PubMed2005

[Expression and function of receptors for advanced glycation end products in bovine corneal endothelial cells].

Corneal endothelial cell loss is a change that occurs with age, but its mechanism is still unclear. We postulated that interaction between advanced glycation end product(AGE) and its receptors is implicated in the corneal endothelial cell loss with age. We investigated the expression of AGE receptors: receptors for AGE(RAGE) and galectin-3 in bovine corneal endothelial cells by reverse transcription-polymerase chain reaction(RT-PCR) and immunohistochemistry. In addition, we investigated the effect of AGE on the cultured corneal endothelial cells. Expression of RAGE and galectin-3 was detected in bovine corneal endothelial cells. Galectin-3 was important in the internalization of AGE. In contrast, RAGE was important in the generation of reactive oxygen species and induction of apoptosis. Based on these data, the interaction of AGE in aqueous humor and AGE receptors expressed on the corneal endothelial cells was speculated to have a role in the corneal endothelial cell loss with age.

Aging↗
PubMed2004

Residual bed thickness and corneal forward shift after laser in situ keratomileusis.

PURPOSE: To prospectively assess the forward shift of the cornea after laser in situ keratomileusis (LASIK) in relation to the residual corneal bed thickness. SETTING: Miyata Eye Hospital, Miyazaki, Japan. METHODS: Laser in situ keratomileusis was performed in 164 eyes of 85 patients with a mean myopic refractive error of -5.6 diopters (D) +/- 2.8 (SD) (range -1.25 to -14.5 D). Corneal topography of the posterior corneal surface was obtained using a scanning-slit topography system before and 1 month after surgery. Similar measurements were performed in 20 eyes of 10 normal subjects at an interval of 1 month. The amount of anteroposterior movement of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affected the forward shift of the corneal back surface. RESULTS: The mean residual corneal bed thickness after laser ablation was 388.0 +/- 35.9 microm (range 308 to 489 microm). After surgery, the posterior corneal surface showed a mean forward shift of 46.4 +/- 27.9 microm, which was significantly larger than the absolute difference of 2 measurements obtained in normal subjects, 2.6 +/- 5.7 microm (P<.0001, Student t test). Variables relevant to the forward shift of the corneal posterior surface were, in order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.736, P<.0001) and the preoperative corneal thickness (B = -0.198, P<.0001). The residual corneal bed thickness was not relevant to the forward shift of the cornea. CONCLUSIONS: Even if a residual corneal bed of 300 microm or thicker is preserved, anterior bulging of the cornea after LASIK can occur. Eyes with thin corneas and high myopia requiring greater laser ablation are more predisposed to an anterior shift of the cornea.

Adult↗
PubMed2004

Corneal regular and irregular astigmatism assessed by Fourier analysis of videokeratography data in normal and pathologic eyes.

PURPOSE: To assess corneal regular and irregular astigmatism using Fourier series harmonic analysis of videokeratography data in normal subjects, as well as in subjects with pathologic and postsurgical conditions. STUDY DESIGN: Retrospective, case-control study. PARTICIPANTS: Two hundred normal eyes, 58 eyes with keratoconus, 24 eyes with suspect keratoconus, 100 eyes that underwent LASIK, 101 eyes that underwent photorefractive keratectomy (PRK), and 79 eyes that underwent penetrating keratoplasty (PK). METHODS: Videokeratography data were decomposed, using Fourier analysis, into spherical power, regular astigmatism, asymmetry, and higher order irregularity. RESULTS: The normal range of the Fourier indices was defined as the mean +/-2xstandard deviation in the normal eyes, which were 40.81-47.13 diopters (D) for spherical power, 0-1.04 D for regular astigmatism, 0.02-0.68 D for asymmetry, and 0.05-0.17 for higher order irregularity. The keratoconus and suspect keratoconus groups showed significantly greater values in all indices than did the normal group (P<0.001 or 0.0001, Mann-Whitney test with Bonferroni correction). Eyes that had undergone LASIK and PRK had significantly smaller spherical power and regular astigmatism (P<0.0001) and significantly larger asymmetry (P<0.0001) than the normal eyes. All indices were significantly greater in the PK group than in the normal group (P<0.0001). Among the eyes tested in this study, eyes with keratoconus had the largest asymmetry, whereas eyes that had undergone PK had the most irregular corneas. CONCLUSIONS: The normal range was defined for the corneal irregular astigmatism index (asymmetry and higher order irregularity) to support future studies in this field. Eyes with ocular pathologic and postsurgical conditions were evaluated using the normal range.

Adolescent↗