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

Purpose Pharmacokinetic 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.Methods We 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 50µl 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 240min after final instillation was determined by high-performance liquid chromatography.Results The maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 ± 1.56µg/ml (60min, OFLX), 2.57 ± 1.00µg/ml (30min, LVFX), and 0.42 ± 0.12µg/ml (120min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 ± 5.62µg/ml (30min, OFLX), 9.02 ± 2.45µg/ml (60min, LVFX), and 8.54 ± 5.17µg/ml (30min, 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.Conclusion Among 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 © Japanese Ophthalmological Society 2004     

Pattern VEP is a useful technique in monitoring the effectiveness of occlusion therapy in amblyopic eyes under occlusion therapy

Purpose To evaluate the effectiveness and clinical significance of pattern visual evoked potential (P-VEP) parameters on visual acuity in amblyopic patients under occlusion therapy.Methods A total of 34 consecutive children with anisometropic amblyopia were included in this study. All patients underwent a full initial ophthalmologic and orthoptic evaluation. P-VEP test was performed in all cases and binocular vision was tested and recorded with Worths four-dot test and Bagolini striated glasses at each visit. Part-time occlusion therapy was performed by using adhesive patches.Results The mean (±SEM) cycloplegic refractive error was +5.6± 0.6 diopters (D) in the amblyopic eyes and +1.8±0.2 D in the normal eye. The mean levels of best-corrected visual acuity were statistically differed between each measurement for occlusion therapy (for each, p<0.05). The ratio of the patients with binocular vision increased after 6months occlusion therapy and the difference was statistically significant (p<0.05). In addition, P100 amplitude improved at each visit and the difference was significant when compared with baseline values (for each,p<0.05).Conclusions P100 amplitude of the P-VEP test parallels the improvement in subjective visual acuity in amblyopic eyes under occlusion therapy. Therefore, this test may be useful in monitoring the visual acuity in the preverbal or non-verbal patched patients.     

Methods of visual acuity determination with the spatial frequency sweep visual evoked potential

Purpose The spatial frequency sweep visual evoked potential (sVEP) is used to rapidly determine visual acuity in children or non-responsive patients. Two techniques have been used to separate signal from noise: (1) the 95% confidence interval for the signal amplitude (95% CI) or (2) the amplitude of a Fourier frequency adjacent to 2×the signal frequency (DFT). The purpose of this study is to determine if there is a significant difference in acuity estimates with these techniques.Methods Ten normal subjects (approximately 0.00logMAR acuity) and 11 patients with decreased visual acuity took part in this project. Stimulus production and data analysis were done with an Enfant 4010 (Neuroscientific Corp). Standard VEP recording techniques were employed. The stimulus was a horizontal-oriented, sine wave grating that swept up the spatial frequency spectrum (contrast 80%, temporal reversal rate 7.5Hz). Sweeps were repeated until the confidence intervals for the data were no longer decreasing. The Bailey LovielogMAR chart was used to determine visual acuity. A line was fit to the high spatial frequency data using either the 95% CI or the DFT as the noise estimate. By using these linear equations, acuity estimates were obtained at 0, 1, and 2V signal amplitudes.Results The average logMAR acuity for the subjects with normal acuity was –0.06±0.070 (SD). The sVEP acuity estimates were 0.08±0.098, 0.18±0.092, and 0.33±0.195 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.07±0.100, 0.18±0.103, and 0.33±0.202 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.10±0.098logMAR. The averagelogMAR acuity for the subjects with decreased visual acuity was 0.67±0.306 (SD). The sVEP acuity estimates were 0.53±0.175, 0.66±0.171, and 0.88±0.295 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.53±0.179, 0.65±0.176, and 0.86±0.268 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.57±0.186logMAR. No significant difference was found between the two acuity estimate techniques for all of the subjects (repeated measures ANOVA, p=0.16, F₂₀=2.131). The sVEP estimates of acuity to the 0V and noise levels were not significantly different from the logMAR acuity (paired t-test, all p values >0.05).Conclusions The results indicate that the sVEP acuity does not depend on the noise estimation technique. In agreement with prior studies, the sVEP acuity underestimates the logMAR acuity in normally sighted individuals by about an octave.     

Change in Corneal Permeability to Timolol After Laser In Situ Keratomileusis and Photorefractive Keratectomy in Rabbit

Purpose To evaluate the change in corneal permeability to timolol 1 month after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) in rabbits.Methods LASIK or PRK was performed on one eye of each of 20 rabbits. One month later, 20µl of 0.5% timolol was instilled into the 10 LASIK eyes, 10 PRK eyes, and the 20 control contralateral eyes. One hour later, 150µl of aqueous humor was collected from all eyes, and the concentration of timolol in the aqueous humor was measured by high-performance liquid chromatography. The effect of LASIK and PRK on the corneal permeability to timolol was analyzed.Results The average timolol concentrations in the aqueous humor of the ten eyes 1 month after LASIK and in the ten contralateral eyes were 1.16 ± 0.58µg/ml and 1.07 ± 0.39µg/ml (average ± SD, P = 0.678), respectively. The average timolol concentrations in the aqueous humor of the ten eyes 1 month after PRK and in the ten contralateral eyes were 1.24 ± 0.43µg/ml and 1.12 ± 0.30µg/ml (P = 0.483), respectively. The average ratio of timolol concentration in the aqueous humor of the LASIK or PRK eyes 1 month after surgery to that of the contralateral normal eyes was 1.18 ± 0.58 or 1.19 ± 0.67 (P = 0.972), respectively.Conclusions LASIK and PRK do not affect corneal permeability to timolol 1 month after surgery. Jpn J Ophthalmol 2005;49:12–14 © Japanese Ophthalmological Society 2005     

Comparing Brimonidine 0.2% to Apraclonidine 1.0% in the Prevention of Intraocular Pressure Elevation and Their Pupillary Effects Following Laser Peripheral Iridotomy

Purpose To compare the effects of brimonidine 0.2% and apraclonidine 1% on intraocular pressure (IOP) and pupil size in patients undergoing laser peripheral iridotomy (LPI).Methods Forty patients (40 eyes) with occludable angle or angle-closure glaucoma requiring LPI were recruited. Patients were randomized to receive either brimonidine 0.2% or apraclonidine 1% before and after LPI. The IOPs were measured at 1, 2 and 3h after LPI, and pupil size was measured before and at 45min after eyedrop instillation. Both parameters were analyzed using the t test.Results There were 20 patients in each group. The baseline IOP was 17.1 ± 3.2mmHg for the brimonidine group and 16.7 ± 2.8mmHg for the apraclonidine group (P = 0.67) (t test). The mean IOP 3h after laser treatment was 18.2 ± 7.8mmHg for the brimonidine group and 15.7 ± 5.6mmHg for the apraclonidine group (P = 0.25) (t test). There was no statistically significant difference between the two groups in the mean IOP changes at 1, 2, or 3h after LPI. The mean change in pupil size after brimonidine was –0.33 ± 0.37mm and after apraclonidine was +0.90 ± 0.87mm. The difference was significant (P < 0.001).Conclusion Brimonidine 0.2% was found to have an efficacy comparable to that of apraclonidine 1.0% in preventing post LPI IOP spikes. Apraclonidine 1.0% tends to have a pupil dilating effect while brimonidine 0.2% tends to constrict the pupil. Jpn J Ophthalmol 2005;49:89–92 © Japanese Ophthalmological Society 2005     

Vitreous Fluid Levels of β-Amyloid(1–42) and Tau in Patients with Retinal Diseases

Purpose A decrease in -amyloid_1–42 (A42) and an increase in tau in the cerebrospinal fluid are reported to be characteristic phenomena in Alzheimers disease patients. To test the idea that A42 and tau contribute to the development of retinal diseases, we measured A42 and tau concentrations in the vitreous fluid from patients with macular hole (n = 13), diabetic retinopathy (n = 15), or glaucoma concurrent with other ocular diseases (n = 8).Methods Vitreous samples were collected from patients who underwent vitrectomy, and sensitive and specific enzyme-linked immunosorbent assays were used to determine the concentrations of A42 and tau.Results By comparison with the levels in the control macular-hole patients (33.9 ± 7.1pg/ml for A42; 3.3 ± 3.2pg/ml for tau), there was a significant decrease in the A42 level and a significant increase in the tau level in patients with diabetic retinopathy (1.8 ± 1.9pg/ml for A42, P = 0.002; 153.7 ± 71.6pg/ml for tau, P = 0.041) or glaucoma concurrent with other ocular diseases (2.8 ± 1.8pg/ml for A42, P = 0.006; 113.6 ± 43.1pg/ml for tau, P = 0.023).Conclusions Our findings indicate the possibility of a role for A42 and tau in the pathogenesis of some retinal diseases. Jpn J Ophthalmol 2005;49:106–108 © Japanese Ophthalmological Society 2005     

A Comparison of Viscogoniotomy with Classical Goniotomy in Turkish Patients

Purpose To compare the success and complication rates of viscogoniotomy and goniotomy in Turkish patients.Methods In a retrospective review, the medical records of patients with primary congenital glaucoma were divided into two groups. Group 1 consisted of 21 patients (38 eyes) who had undergone classical goniotomy, and group 2 consisted of 25 patients (44 eyes) who had undergone viscogoniotomy. The success rates and intra- and postoperative complications were compared between the two groups.Results Mean preoperative introcular pressure (IOP) was 28.9 ± 3.6mmHg in group 1 and 29.3 ± 2.8mmHg in group 2. At the last postoperative visit, it was 17.3 ± 3.1mmHg and 16.2 ± 2.1mmHg, respectively (P < 0.001). The success rates at the last visit of group 1 and group 2 were 68.4% and 88.6%, respectively (P < 0.05). The most common early postoperative complication was hyphema in group 1 and transient IOP elevation in group 2.Conclusion Viscogoniotomy may increase the success rate and decrease the complications rate by preventing hyphema and flat anterior chamber. Jpn J Ophthalmol 2004;48:404–407 © Japanese Ophthalmological Society 2004     

Binding Affinity of Bunazosin,Dorzolamide, and Timolol to Synthetic Melanin

Purpose The purpose of this study was to compare the binding affinity of bunazosin and dorzolamide to synthetic melanin relative to that of timolol.Methods Synthetic melanin was prepared from dopa by the action of tyrosinase. Timolol, dorzolamide, and bunazosin were incubated separately at a concentration of 10^–4M in 2ml of 0.066M phosphate buffer containing 5mg of synthetic melanin. After centrifugation, the absorbance of each free drug in the supernatant was measured at its optimum wavelength. The percentage of each drug bound to melanin was calculated directly from the change in absorbance relative to the initial value.Results The increase in the binding rates of all three drugs seemed to reach a plateau after 30min. After incubating for 60min, the binding rate of timolol was 22.2% ± 4.9%, bunazosin 36.3% ± 2.5%, and dorzolamide 8.5% ± 1.9%. There were statistically significant differences between the binding rates of each drug.Conclusions Under our study conditions, the order of binding affinity of these ocular hypotensive agents to synthetic melanin seems to be as follows: bunazosin timolol dorzolamide. Jpn J Ophthalmol 2004;48:34–36 © Japanese Ophthalmological Society 2004     

Epidemic Nosocomial Keratoconjunctivitis Caused by Adenovirus Type 4

Purpose Presently, there are no completely reliable examinations such as focus from a distant place to a near place during daily work. We developed a simple testing system for accommodation time using a 5m chart and a laptop computer.Material and Methods We studied 177 healthy subjects. They turned their eyes from the 5m chart to the display of the personal computer at about 70cm in front of the eyes. We measured the minimum time (MTC) for recognizing three Kanji (Chinese characters) randomly chosen from a total of 15 characters on the display.Result The MTCs with +1.25D added were shorter than those with complete correction. The MTCs in both conditions extended with age. In subjects less than 40 years old, the MTCs measured with both eyes were significantly shorter than those with a single eye completely corrected. In subjects over 40 years old, there was no difference. The MTCs were shorter significantly with complete correction than with +1.25D added. The MTCs decreased as the accommodative amplitude increased.Conclusions There is significant correlation between the accommodative amplitude and the MTCs. We can use the MTCs as one method of measuring time of accommodation. Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc 107:380–387, 2003)     

Corneal Thickness in Eyes Following Pars Plana Lensectomy for Congenital Cataracts

Purpose To evaluate the corneal thickness following pars plana lensectomy for congenital cataracts.Methods The corneal thickness was measured in 24 eyes of 24 patients with congenital cataracts who had undergone pars plana lensectomy at a mean age of 24 ± 32 (SD) months. The mean age at the time of our evaluation was 15 ± 3 years. These measurements were compared with those in 15 eyes of an age-matched group of 15 normal volunteers. The central corneal thickness and endothelium were evaluated in both groups.Results The mean corneal thickness of the cataract-extracted eyes (592 ± 47µm) was significantly greater than that of the controls (529 ± 43µm; P 0.00l). There was no significant difference in the corneal endothelial cell count between cataract-extracted eyes (3420 ± 715/mm²) and the controls (3182 ± 358/mm²; P = 0.49). However, there were significant differences in the frequency of hexagonally shaped endothelial cells (63% ± 8.4%, cataract-extracted eyes; 70% ± 7.7%, controls; P 0.0l), and in the coefficient of variation in the endothelial cell size (33 ± 6.0, cataract-extracted eyes; 26 ± 4.8, controls; P 0.01).Conclusion The central cornea of congenital cataract-extracted eyes was significantly thicker than that of controls. Jpn J Ophthalmol 2004;48:169–171 © Japanese Ophthalmological Society 2004     

Relaxing incisions with compression sutures for control of astigmatism after penetrating keratoplasty

Background: Ten percent of patients with persisting postoperative astigmatism following penetrating keratoplasty (PK) require surgical re-intervention, despite an otherwise successful transplant. Relaxing incisions (RIs) in combination with compression sutures seem to be the preferable procedure. However, poor predictability and lack of long-term experience complicate the issue. Here we report the 2-year follow-up results of 25 patients with high PK astigmatism treated by means of RIs and compression sutures Methods: Commonly, free-handed RIs were placed at the graft-host interface and 10–0 nylon compression sutures were placed perpendicular to the incisions. PK sutures had been removed no less than 4 months prior to refractive surgery Results: Nineteen eyes regained a functional vision of >- 0.4. The net decrease in astigmatism was 6.1 ± 4.3 D (47 ± 21 %). The mean vector-corrected change in astigmatism was 13.1 ± 5.7 D. Cylinder axis variation was reasonably low, with a correlation of attempted versus achieved axis of r=0.85. Within the first 3 months after operation the induced astigmatism regressed by, on average, 5.5 ± 4.3 D, making intraoperative overcorrection necessary. As an inevitable side effect, refractive procedures resulted in a myopic shift (4.7 ± 6.9 D) in spherical equivalence Conclusion: RIs and compression sutures are very useful in reducing postkeratoplasty astigmatism if correction of extremely high cylinder (> 10 D) is not intended. However, predictability still remains unsatisfactory and more than one operation may be required.     

Effects of an Eyeglass-free 3-D Display on the Human Visual System

Purpose To investigate the effect on the human visual system of viewing 3-dimensional (3-D) computer graphics (CG) images with an eyeglass-free rear-cross-lenticular-type 3-D display.Methods Positive accommodation velocity (GRAD) during the accommodative step response was measured in ten healthy young adults before and after they viewed CG images. Although the distance between the viewer and the 3-D display was 600mm, the apparent distance between the viewer and the virtual object was varied (515, 600, and 722mm) by changing the visual disparity.Results A significant slowdown of average GRAD was observed by 60min after a 30-min 3-D viewing of 3-D CG images [P 0.05, analysis of variance (ANOVA)] but not after a 30-min viewing of the CG images on a 2-D display or after a 15-min 3-D viewing. When the virtual object was at 722mm, a significant slowdown of average GRAD was observed only at 30min after the 30-min 3-D viewing (P 0.05, ANOVA). When the virtual object was at 515mm, a significant slowdown of average GRAD was observed at 30 and 60min after the 3-D viewing (P 0.05, ANOVA).Conclusions The effect on the human visual system of 3-D viewing of 3-D CG images depends on both the duration of the viewing and the apparent distance between the viewer and the virtual objects. Jpn J Ophthalmol 2004;48:1–6 © Japanese Ophthalmological Society 2004     

The effect of body temperature on the murine electroretinogram

Purpose: To study the effect of body temperature on the murine electroretinogram (ERG). Methods: The corneal ERG elicited by a strobe flash from dark-adapted mice was recorded using a saline wick electrode while measuring rectal temperature continuously. The mouse was placed within a cylindrical coil of tubing through which water circulated from a temperature controlled bath. The body temperature of the mouse was changed stepwise between 30 and 37°C. Results: ERGs of approximately normal configuration were recorded at body temperature ranging between 30 and 37°C. The maximum amplitude of the a- and b-waves varied linearly with temperature. The rate of change of b-wave amplitude was about 100 V/degree. At 30°C, maximum b-wave amplitude was about 400 V; at 37°C it was about 1000 V. A change in body temperature produced a rapid change in ERG amplitude. Conclusion: The murine ERG is very sensitive to changes in temperature. In order to monitor the ERG accurately over time, continuous recording of body temperature is essential.     

Sialic Acid in Human Tear Fluid Decreases in Dry Eye

Purpose To evaluate the association between tear mucin and dry eye, we compared tear fluid sialic acid concentration in dry eye patients with that in normal volunteers. We also compared the sialic acid concentration with the results of several different types of dry eye examinations.Methods Subjects comprised 16 age-matched, normal healthy controls and 45 dry eye patients. Dry eye examinations included fluorescein staining, rose bengal staining, Schirmer I test, cotton thread test, and fluorescein breakup time. Tear samples were collected with a micropipette after the instillation of 50µl saline. The sialic acid concentration was measured by high-performance liquid chromatography.Results The sialic acid concentration was significantly lower in the dry eye group (5.3 ± 4.3µg/ml) than in the control group (37.1 ± 28.3µg/ml) (P < 0.001). Also, the sialic acid concentration correlated significantly with the results of dry eye examinations (P < 0.0002).Conclusions The different sialic acid levels in the control and dry eyes may imply differences in the quantity or quality of glycoprotein in tears between these two groups. Thus, sialic acid, a component of mucin, may play a key role in the dry eye condition. Jpn J Ophthalmol 2004;48:519–523 © Japanese Ophthalmological Society 2004     

Superior Segmental Optic Hypoplasia Found in Tajimi Eye Health Care Project Participants

Purpose To investigate the prevalence and characteristics of superior segmental optic hypoplasia in Japanese.Methods We studied 14779 subjects, aged 40 years or older, who underwent IMAGEnet fundus photography as part of a large-scale eye disease screening project conducted in Tajimi, Japan. A single researcher reviewed all of the photographs for the presence of ocular abnormality in the optic nerve head and retina, paying special attention to the presence of superior segmental optic hypoplasia.Results Fundus photographs of 14431 cases (28396 eyes) were successfully reviewed. We found superior segmental optic hypoplasia in 37 cases (54 eyes; 0.3% of the cases and 0.2% of the eyes). Of the 37 cases, 23 (62%) showed the corresponding visual field defect in at least one eye.Conclusion The prevalence of superior segmental optic hypoplasia is about 0.3% in the Japanese population. Jpn J Ophthalmol 2004;48:578–583 © Japanese Ophthalmological Society 2004     

Cytotoxicity of Triamcinolone on Cultured Human Retinal Pigment Epithelial Cells: Comparison with Dexamethasone and Hydrocortisone

Purpose Triamcinolone acetonide (TA) is a corticosteroid that can be used in the treatment of cystoid macular edema (CME) and other ocular inflammatory conditions. This study aims to investigate the degree of cytotoxic effect of TA on human retinal pigment epithelium (ARPE19 cell line) and to compare the relative toxicity of TA with two other corticosteroids, hydrocortisone (HC) and dexamethasone (DEX), over a range of concentrations and durations of exposure.Methods The ARPE19 cell line was cultured and maintained in a 1:1 mixture of Dulbeccos modified Eagles medium and HAMS F12 medium containing 3mM l-glutamine supplemented with 10% fetal bovine serum, penicillin G, and streptomycin sulfate. Following an initial overnight incubation, corticosteroids (0.01–1mg/ml) or vehicle (benzyl alcohol, 0.025%), diluted in culture medium, was added to the ARPE19 culture (5000 cells/well) on Day 0. Subsequently the culture medium containing corticosteroid or vehicle was refreshed daily. After 1, 3, and 5 days, the proliferated amount of cells with and without corticosteroid treatment was determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. All samples were read in triplicate, with n = 4 in all cases. The final results were analyzed using analysis of variance.Results TA, DEX, and HC caused a significant reduction in cell numbers throughout the whole range of concentrations when cells were exposed to them for more than one day. The action of the corticosteroids, apart from TA, was biphasic. There was an initial rise in cell proliferation in the presence of DEX and HC at 0.01–0.1mg/ml on Day 1. Log-linear plots of DEX and HC concentrations against percent viability (mean % ± SD) showed a significantly higher total viable cell percentage versus TA: 120.5 ± 1.8% and 134.9 ± 4.1% in the presence of DEX, and 110.0 ± 15.3% and 118.3 ± 9.0% in the presence of HC. The LD₅₀ values of the three corticosteroids show that, regardless of the duration of exposure, TA was the most toxic, with relative toxicity of TA > DEX > HC, equivalent to a ratio of 1.0:1.6:1.8, after one day of incubation. The vehicle alone had no effect.Conclusions The present study demonstrated the degree of cytotoxicity of TA compared with DEX and HC. The results provide a profile of this drug relative to other common corticosteroids. Further studies are planned to characterize its effects and the degree of influence on cells of different ocular regions in order to show the full cytotoxicity of TA. Jpn J Ophthalmol 2004;48:236–242 © Japanese Ophthalmological Society 2004     

Unique Characteristics of Two Types of Retinitis Pigmentosa Patients with Different Rod Sensitivities

Purpose To determine the psychophysical differences between two types of retinitis pigmentosa (RP) patients with different rod sensitivities.Methods Thirty-five RP patients with a visual acuity of 0.7 or better were classified by cone–rod perimetry into type 1, those with undetectable rod sensitivity, and type 2, those with measurable rod sensitivity. Their symptoms, age at onset of symptoms, cone and rod sensitivity, and full-field electroretinograms (ERGs) were compared.Results The age when the symptoms of night blindness were first noticed was 13.1 ± 3.3 years (mean ± SD) for type 1 and 34.5 ± 14.4 years for type 2 patients (P = 0.0001). One of nine type 1 patients (11%) and 10 of 26 type 2 patients (38%) did not have any symptoms of night blindness. The average rod sensitivity within the central 10° was 43.7 ± 12.0dB for type 2 patients with night blindness, and 54.8 ± 6.4dB for type 2 patients without night blindness (P = 0.014). One of nine (11%) type 1 patients and 9 of 23 (39%) type 2 patients had recordable ERGs (P = 0.13).Conclusions These findings indicate that the two types of RP patients, distinguished by their rod sensitivity, have different psychophysical characteristics of the visual system. The course of the disease process and the long-term prognosis for these two types of patients are different. Jpn J Ophthalmol 2005;49:114–120 © Japanese Ophthalmological Society 2005     

Quantitative Evaluation of Ischemia–Reperfusion Injury by Optical Coherence Tomography in the Rat Retina

Purpose To determine whether optical coherence tomography (OCT) can detect early retinal changes after ischemia–reperfusion injury in rats.Methods The intraocular pressure (IOP) was elevated to induce retinal ischemia in brown Norway rats. After 90min of ischemia, the IOP was reduced, and after reperfusion of 1, 2, 4, or 7 days, OCT was performed. After the OCT examination, the eyes were enucleated and histological sections were made.Results The OCT-determined mean retinal thickness was 168 ± 16.9µm in the untreated control group, and 177 ± 2.16, 170 ± 7.55, 159 ± 5.34, and 140 ± 5.56µm on days 1, 2, 4, and 7, respectively, in the ischemia–reperfusion group. The histologically determined retinal thicknesses correlated with those obtained by tomographic images, but the histologic thicknesses were 9.5% to 18.5% thinner than those obtained by OCT. Fixation and dehydration of the histological specimens most likely caused tissue shrinkage.Conclusions OCT can detect retinal changes quantitatively after ischemia–reperfusion injury, and the retinal thicknesses obtained from OCT images are probably a better measure of the true retinal thickness than those measured on histological sections. Jpn J Ophthalmol 2005;49:109–113 © Japanese Ophthalmological Society 2005     

Transition from Upbeat to Downbeat Nystagmus Observed in a Patient with Wernicke’s Encephalopathy

Background We report an unusual case of Wernickes encephalopathy presenting with transient upbeat nystagmus that changed to a persistent downbeat nystagmus.Case A 27-year-old man presented with upbeat nystagmus. Three months earlier, he had been diagnosed with Wernickes encephalopathy after fasting for a month.Observations This diagnosis was supported by his symptoms (ataxia, a confused state). Clinical recovery followed thiamine therapy. His upbeat nystagmus had linear slow phases with average amplitude and frequency (±SD) during fixation straight ahead of 2.8 ± 0.7° and 4.6 ± 2.2Hz, respectively. Two months later, the primary position upbeat nystagmus had diminished and downbeat nystagmus (0.9 ± 0.5° and 3.2 ± 0.7Hz on average) for a 20° downward gaze had developed. Then, 8 months later, he showed only downbeat nystagmus, which obeyed Alexanders law. His primary position downbeat nystagmus was completely suppressed by clonazepam, a -aminobutyric acid (GABA) agonist.Conclusions Owing to an underlying central vestibular imbalance, even after the recovery of acute neurological symptoms, Wernickes encephalopathy can be complicated by persistent downbeat nystagmus, which can be treated by a GABA agonist. Jpn J Ophthalmol 2005;49:220–222 © Japanese Ophthalmological Society 2005     

Lamellar excimer laser keratoplasty: Reproducible photoablation of corneal tissue

We examined the depth of ablation of the recipient bed with different counts of oscillations of excimer laser beam, to determine the correlation between planned and real depth. The ablation rate per oscillation was tested preoperatively by blackened photographic paper of defined thickness and thus was calculated to be 5 m. Forty pig eyes were used for the first study. Each eight eyes were ablated in the planned depth 100 m, 200 m, 300 m, 400 m and 500 m. The corneal thickness was measured with an ultrasonic pachymeter before and after the procedure. The depth measured after the photoablation was 99.4 ± 36.4 m for 100 m planned depth, 186.7 ± 55.3 m for 200 m, 298.4 ± 68.5 m for 300 m, 373.9 ± 65.7 m for 400 m and 480.1 ± 59.3 m for 500 m. Comparing the depth measured after the photoablation to planned depth, there was a significant correlation (correlation coefficient: R = 0.93; p < 0.0001). Five other corneas trephinated from pig cadaver eyes were ablated from the endothelial side to the desired thickness (100 to 500 m) of lamellar graft. In a second step a donor mask was placed onto the cornea and a laser light spot was led until perforating on all sides. The lamellar keratoplasty was completed by suturing the corneal graft into the bed. Macroscopic and microscopic examination of sutured eyes after fixation showed a good fit of wound margins and stromal interface. These results indicate that excimer laser is useful for reproducible corneal photoablation in lamellar keratoplasty.