Nobuo Takahashi

The Reykjavik Eye Study--prevalence of lens opacification with reference to identical Japanese studies.

Purpose: A population-based cataract epidemiological study, the Reykjavik Eye Study, was conducted to determine the prevalence and characteristics of lens opacities in Iceland. The results were compared with those from previous surveys in Japan to determine the influence of race and environmental factors. Methods: 1,635 randomly selected residents of Reykjavik, Iceland, were enrolled, and among them, 1,045 responded and took part in the study. The subjects received ophthalmological examination of both the anterior and the posterior segments. Changes in the crystalline lens were examined and photographed under maximal pupillary dilation. Classification of the opacity types and grading of the extent of lens opacificiation were done using a standardized scheme, and the data were analyzed with Student’s test, the χ2 test and the Mantel-Haenszel test. Results: The prevalence of lens opacities in subjects in their 50s, 60s, 70s and in those 80 years and older was 42.7, 61.0, 85.3 and 100%, respectively. Grade II and III lens opacities were found in 2.2% of subjects in their 50s and in 10.5, 35.9 and 62.3% in their 60s, 70s, and over 80 years, respectively. Cortical opacities predominated in all age groups followed by nuclear opacities; subcapsular opacities, on the other hand, were quite rare. A unique type of opacity, i.e., granular opacity, seldom seen among the Japanese, was found in 6.6% of the Icelandic subjects. Conclusions: Our results show that cortical opacity is the major type of opacity in Icelandic subjects, although its prevalence was lower than that in the Japanese subjects. Interestingly, the first appearance of lens opacities of grades II and III in Icelanders was delayed by 10 years compared to the Japanese suggesting fewer or less severe risk factors for cataract formation in Iceland.

A new method evaluating quantitative time-dependent cytotoxicity of ophthalmic solutions in cell culture. Beta-adrenergic blocking agents

A new method of evaluating quantitative cytotoxicity in cell culture was demonstrated using Changs cultured human conjunctival cells. Time-dependent cytotoxicity of some beta-adrenergic blocking agents was shown and expressed by exposure time, causing 50% cell damage (50% cell damage time, CDT50).Pure timolol maleate of 0.25% and 0.5% concentration caused no cytotoxicity within a 64-min exposure. Pure befunolol hydrochloride of 0.25%, 0.5% and 1% inhibited 10%–30% of cell growth at 64-min exposure. Pure bupranolol of 0.125%, 0.25%, 0.5% and 1% showed evident cytotoxicity and CDT50 at 66 min 48 s, 38 min 54 s, 3 min 46 s and 1 min 18 s, respectively.Commercial preparations, which contained benzalkonium chloride as a preservative, indicated more rapid cytotoxicity. Timolol preparations of 0.25% and 0.5% showed CDT50 at 48.1 s and 2 min 4 s, respectively. Befunolol preparations of 0.25%, 0.5% and 1% showed CDT50 at 43.4 s, 4 min 38 s and 58 s, respectively. Bupranolol preparations of 0.125%, 0.25%, 0.5% and 1% demonstrated CDT50 at 1 min 11 s, 3 min 24 s, 22.3 s and 13.7 s, respectively.

Expression of Matrix Metalloproteinases in Wound Healing after Glaucoma Filtration Surgery in Rabbits

Purpose: To investigate the protein and mRNA expressions of matrix metalloproteinases (MMPs), gelatinolytic activity and localization of MMP activity in wounds after glaucoma filtration surgery in rabbits. Methods: Sixty eyes of 30 rabbits were removed 1, 3, 7, 14 and 120 days after the surgery and used for this experiment. Protein and mRNA expressions were analyzed by immunohistochemistry and laser capture microdissection/real-time RT-PCR, respectively. The gelatinolytic activity was analyzed by gelatin zymography and the localization was studied using in situ zymography. Results: By immunohistochemistry, expression of MMP-1, MMP-2, MMP-3, MMP-9 and MT1-MMP was detected in the wounds, most markedly 3 days after the surgery. MMP-positive cells were predominantly macrophages. Expression of MMP-9 and MT1-MMP mRNAs was verified by RT-PCR. Gelatinolytic activities corresponding to proMMP-2 and the active form of MMP-2 were detected in the wounds 3 and 7 days after surgery. In situ zymography localized gelatinolytic activities at the wound site. These activities were almost completely abolished by an MMP inhibitor, indicating that the gelatinolytic activity belongs to metalloproteinases. Conclusions: MMPs, particularly MMP-2/MT1-MMP, play important roles in the degradation of the extracellular matrix in the wound healing process after glaucoma filtration surgery and may represent an important target for therapeutic intervention after glaucoma filtration surgery.

The Effect of the Corneal Epithelium on the Intraocular Penetration of Fluoroquinolone Ophthalmic Solution

PurposePharmacokinetic studies of antibacterial agents for infectious eye diseases have usually been performed on normal rabbit eyes. In this study, the intraocular penetration of fluoroquinolone ophthalmic solutions was determined in normal rabbit eyes and in rabbit eyes that had the corneal epithelium intentionally removed.MethodsWe determined the intraocular penetration of ofloxacin (OFLX), levofloxacin (LVFX), and norfloxacin (NFLX), fluoroquinolone ophthalmic solutions that are already on the market and undergoing clinical studies, by injecting 50 µl of each solution into the cul-de-sacs of rabbit eyes three times at 15-min intervals. The drug concentration at 10, 30, 60, 120, and 240 min after final instillation was determined by high-performance liquid chromatography.ResultsThe maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 ± 1.56 µg/ml (60 min, OFLX), 2.57 ± 1.00 µg/ml (30 min, LVFX), and 0.42 ± 0.12 µg/ml (120 min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 ± 5.62 µg/ml (30 min, OFLX), 9.02 ± 2.45 µg/ml (60 min, LVFX), and 8.54 ± 5.17 µg/ml (30 min, NFLX). The drug penetration of the eye drops into eyes with removed corneal epithelium was around 6 times (OFLX), 3.5 times (LVFX), and 20 times (NFLX) higher than the penetration into the eye with normal cornea.ConclusionAmong the pharmacokinetic parameters of the three ophthalmic solutions according to the one-compartment model, the maximum concentration in the aqueous and the area under the concentration–time curve in the aqueous tended to be higher in the eyes with intentionally removed corneal epithelia than in those with normal corneas. Jpn J Ophthalmol 2004;48:93–96

Early Manifestation of Vogt-Koyanagi-Harada Disease as Unilateral Posterior Scleritis

PURPOSE To describe a patient with an initial diagnosis of unilateral posterior scleritis who developed bilateral Vogt-Koyanagi-Harada (VKH) disease 12 months later. CASE A 38-year-old woman was diagnosed with posterior scleritis in her right eye at successive examinations. The left eye showed no signs of ocular inflammation. OBSERVATIONS Her right eye developed a second attack of posterior scleritis 3 months after the initial diagnosis. Twelve months after the first incident, granulomatous uveitis and sunset glow fundus were observed in both eyes. At the same time, lymphocytosis was found in the cerebrospinal fluid, and she was HLA DR-4-positive. In addition, poliosis was noted. CONCLUSIONS The final diagnosis was primarily VKH disease with presenting signs and symptoms of unilateral posterior scleritis. We therefore recommend that when following a patient with posterior scleritis include VKH disease in the differential diagnosis.

Quantitative Chamber Angle Measurement Utilizing Image-Processing Techniques

An image-processing technique was applied to the measurement of the anterior chamber angle. The anterior eye segment was documented by a new instrument, named anterior eye segment analysis system for biometry of the anterior eye segment. The approximated curve of the corneal posterior curvature and the line tangent to the anterior surface of the iris were calculated as the anterior chamber angle. The mean error of the reproducibility of repeated measurements for the same image was 1.6 +/- 0.81% and that of 3 images of the same eye which were taken at 3 different times was within 5.2%.

Environmental temperature and cataract progression in experimental rat cataract models.

PURPOSE To clarify whether or not ambient temperature relates to cataract development or the progression of cataract formation. MATERIALS AND METHODS 36 Brown Norway rats were divided into two groups, a high-temperature (35 +/- 2 degrees C, H = high) breeding group and a regular-temperature (24 +/- 2 degrees C, L = low) group. Each group was further divided into an experimentally induced diabetic cataract subgroup (50 mg/kg streptozotocin, DM), an ultraviolet B exposure-induced cataract subgroup (200 mJ/cm2, UV), and a normal control subgroup (C = control). Slit-lamp microscopy and an anterior image analysis system (EAS-1000) were used to evaluate lens changes. RESULTS Both the HC and HUV groups in the 35 degrees C conditions showed higher light scattering than that of the 24 degrees C conditions (LC and LUV) 3 weeks after the start of the experiment. Nine weeks after the start of the experiment, all the rats of the UV subgroups (HUV and LUV) developed anterior subcapsular cataract. The temperature did not have much influence on the progression of the UV-B-induced cataract. From 18 days after the start of the experiment, the HC subgroup showed a wider light scattering area than the LC. An increase in abnormal nuclear scattering light in the crystalline lens of group HC was found in 9 weeks after the start of the experiment, and at the end of the experiment (78 weeks later), dense abnormal nuclear light scattering was found including the prenuclear area. In contrast, the HDM group in the 35 degrees C conditions showed slower cataract progression than that of the LDM group at 24 degrees C room temperature. CONCLUSIONS Although further experiments are necessary before we can draw any conclusions about temperature and nuclear changes, paying attention to the effects of temperature on the lens is worthwhile.

Cytotoxicity and Characteristics of Mitomycin C

In order to evaluate the cytotoxicity of mitomycin C (MMC), the effects of MMC on cell viability, cell cycle and cell surface structure were studied using Changs cultured human conjunctival cells. A 4- or 2-min exposure to MMC at concentrations ranging from 0.002 to 0.04% decreased the cell viability. The cell number was remarkably reduced by exposure to MMC over 0.004%. MMC at a concentration higher than 0.001% arrested the DNA synthetic phase of the cell cycle. MMC even at a high concentration (0.04%) did not cause any direct alteration to the cell surface.

Safety comparison of additives in antiglaucoma prostaglandin (PG) analog ophthalmic formulations

Purpose To investigate the safety of five types of antiglaucoma prostaglandin analog ophthalmic formulations, and to clarify their differences in accordance with contained additives (preservatives and surface-active agents). Methods The following five types of ophthalmic solutions and three types of additives were investigated: latanoprost (Xalatan®; latanoprost), tafluprost (Tapros®; tafluprost), bimatoprost (Lumigan®; bimatoprost), travoprost (Travatan®; travoprost), travoprost (Travatan Z®; travoprost-Z), benzalkonium chloride (BAK), polyoxyethylene hardening castor oil 40 (HCO-40), and polysorbate 80 (P-80). These experimental solutions were exposed to the cultured cells of a rabbit-derived corneal cell line for a certain time, and the exposure time causing 50% cell damage (CD50), indicated by the ratio of viable cells to total cells was calculated (in vitro). In addition, corneal resistance (CR) was measured and CR ratio (post-treatment CR/pretreatment CR × 100) was calculated (in vivo). Results CD50 of each ophthalmic solution was the longest with tafluprost, followed by travoprost-Z, bimatoprost, travoprost, and latanoprost. CD50 of 0.005%, 0.01%, and 0.02% BAK was 14.5 minutes, 8.1 minutes, and 4.0 minutes, respectively. The number of viable cells decreased to 60%, 8 minutes after exposure with HCO-40, and 30 minutes after being exposed to P-80. The CR ratio was 81.0% with travoprost and 82.0% with latanoprost, indicating a significant posttreatment reduction of CR (P < 0.05). The CR ratio did not decrease after treatment with tafluprost, travoprost-Z, or bimatoprost. The CR ratio of 0.005%, 0.01%, and 0.02% BAK was 105.0%, 90.5%, and 68.7%, respectively, and that of HCO-40 and P-80 was 108.7% and 114.2%, respectively. Conclusion BAK, HCO-40, and P-80 were thought to be involved in corneal injuries caused by each ophthalmic solution. Corneal injuries due to surface action were observed when using HCO-40 and P-80. When HCO-40 was combined with BAK, it induced micellar BAK and reduced corneal injuries by BAK.

Predicting postoperative anterior chamber depth in cataract patients using Scheimpflug slit photography

Purpose: To predict the postoperative anterior chamber (AC) depth from the preoperative in situ position of the lens central clear zone (CCZ) using Scheimpflug slit photography. Methods: 111 eyes of 78 cases that underwent phacoemulsification and intraocular lens (IOL) implantation were examined. 748 eyes of 383 healthy subjects with transparent lenses were used as the control. Scheimpflug slit photography was done under maximal mydriasis, and biometry was performed on the photographs. Two types of acrylic IOLs (MA30BA and MA60BM, both from Alcon) were used in this study. The preoperative AC depth (L1), the distance between the anterior lens capsule and lens CCZ (L2) and the postoperative AC depth (I1) were determined. I2, the predicted postoperative AC depth, was then determined from a linear regression of L1 + L2 and I1. Results: L2 thickened by 0.014 mm/year, and L1 decreased by 0.016 mm/year in the transparent lenses. L1 + L2 changed little with aging in both cataractous and transparent lenses. L1 + L2 and I1 showed a linear correlation with r = 0.80 in the MA30BA and r = 0.77 in the MA60BM groups. The mean error values between I1 and I2 were 0.095 ± 0.096 and 0.123 ± 0.114 mm in MA30BA and MA60BM, respectively. The error between I1 and I2 was within ± 0.17 and ± 0.33 mm or less in 72.9 and 91.5% of MA30BA and in 82.7 and 96.2% of MA60BM. In contrast, the error between I2 and I1 when calculated using the SRK/T formula was much larger – in excess of ± 0.33 mm in 38.7% of the eyes. Conclusions: L1 + L2 changes little with aging and is considered a useful marker of the position of the crystalline lens in situ. There was a high correlation between I1 and L1 + L2. These allow a far more accurate prediction of I1 than previous methods. In combination with the conventional regression formula and ray tracing, a highly accurate IOL power calculation can be attained.