Noritake Miyamura

RETINAL CAPILLARY CHANGES IN OTSUKA LONG-EVANS TOKUSHIMA FATTY RATS (SPONTANEOUSLY DIABETIC STRAIN) : ELECTRON-MICROSCOPIC STUDY

The Otsuka Long-Evans Tokushima fatty (OLETF) rat is a spontaneously diabetic strain with polyuria, polydipsia and mild obesity. The pathological features of OLETF rats closely resemble those of patients with non-insulin-dependent diabetes mellitus. The purpose of this study is to investigate the retinal capillary changes in the OLETF rat and to confirm the valuability of the OLETF rat as the model of diabetic retinal disease. One-month-old male OLETF rats and age- and sex-matched Long-Evans Tokushima Otsuka (LETO) controls were supplied by Otsuka Pharmaceutical Co. Ltd. (Tokushima, Japan). Body weight and blood sugar levels were measured monthly. Their eyes were enucleated 14 months after birth. Ultrathin sections were made and examined with a transmission electron microscope. According to their location, two kinds of retinal capillaries were differentiated: those in the nerve fiber layer (NFL) and those in the outer plexiform layer (OPL). The image of each capillary was transferred to a computed image analyzer, and basement membrane thickness and the ratio of the pericyte area to total capillary cross-section area were determined. Corrosion casts of retinal vessels were made and examined with scanning electron microscopy (SEM). OLETF rats gained more weight than LETO rats from the beginning, and the difference increased gradually with age. The blood sugar level of OLETF rats was higher than that of LETO rats after 5 months of age. In the retinal capillaries of 14-month-old OLETF rats, basement membranes were significantly thicker (OLETF: 209 ± 51 nm in NFL, 132 ± 23 nm in OPL; LETO: 118 ± 28 nm in NFL, 79 ± 14 nm in OPL), and the ratio of pericyte area to the capillary cross-section area was significantly lower than that of the controls (OLETF: 0.131 ± 0.92 in NFL, 0.111 ± 0.102 in OPL; LETO: 0.288 ± 0.142 in NFL, 0.198 ± 0.136 in OPL). The endothelial cell cytoplasm had degenerated. SEM examination of the vascular corrosion cast of a 14-month-old OLETF rat showed caliber irregularity, narrowing, tortuosity and loop formations of capillaries. The morphological changes in the retinal capillaries of OLETF rats were similar to those seen in diabetic patients. The OLETF rat may be a useful animal model for the study of ocular diabetic complications in humans.

Retinal vascular obstruction and asymptomatic cerebral infarction

PURPOSE The purpose of this study is to clarify the relationship between retinal vascular obstruction and asymptomatic cerebral infarction (ACI). METHODS Forty-three patients (27 men and 16 women) with retinal vascular obstruction were examined by magnetic resonance imaging (MRI) at the Department of Ophthalmology of Nagasaki University Hospital in Nagasaki, Japan. Patients with a history of neurological signs and symptoms were excluded from this study. The control group consisted of 93 male and 49 female patients who were examined by MRI for routine brain screening examinations at the Takaki Neurosurgical Clinic in Fukuoka, Japan. We investigated the incidence of ACI, and the risk factors and characteristics of this condition. RESULTS ACI was more common in patients with retinal vascular obstruction than in normal adults at all ages. The incidence of hypertension in the patients with ACI tended to be higher than in the patients without ACI. CONCLUSION ACI appears more frequently in patients with retinal vascular obstruction than in normal adults. Our results indicate that either retinal artery occlusion or retinal vein occlusion should be considered a sign of ACI and systemic diseases such as arteriosclerosis.

Long-term Follow-up of Full Macular Translocation for Choroidal Neovascularization

PURPOSE To report the long-term (>5 years) results of full macular translocation in patients with choroidal neovascularization (CNV). DESIGN Retrospective, interventional case series. METHODS This study involved 32 eyes of 32 patients who had undergone full macular translocation for CNV. The median follow-up was 6.5 years (range, 5.2 to 7.7 years). We evaluated the best-corrected visual acuity, fundus examination results obtained before and 1 and 5 years after operation, and postoperative complications. RESULTS At the 1-year follow-up, foveal retinal pigment epithelium atrophy was observed in only 3 eyes (12%), and the mean logarithm of the minimal angle of resolution (logMAR) visual acuity (VA) at that time (1.39 +/- 0.67) was not significantly changed from that before surgery (logMAR, 1.31 +/- 0.66) in 25 eyes with age-related macular degeneration (AMD). However, at 5-year follow-up, foveal retinal pigment epithelium atrophy increased (18 eyes; 72%), and final mean logMAR VA (1.88 +/- 0.76) was significantly lower (P < .01). Five eyes with myopic CNV maintained their VA from before operation (mean logMAR, 0.88 +/- 0.35) until final follow-up (mean logMAR, 0.73 +/- 0.31). The final VA was significantly better in myopic CNV than in exudative age-related macular degeneration on multiple regression analysis (P = .019). CONCLUSIONS Long-term follow-up of full macular translocation showed that the final VA was poor in age-related macular degeneration, but relatively better in myopic CNV.

Vascular Architecture of Degenerated Retina in WBN/Kob Rats: Corrosion Cast and Electron Microscopic Study

The purpose of the present study is to determine the changes of vascular architecture in the degenerated retina. We used mainly corrosion casts of the retinal vasculature and scanning electron microscopy to obtain a wide three-dimensional view. WBN/Kob rats (a spontaneously diabetic strain) were used because their outer retinas degenerate and become very thin with age. In 15-month-old rats, localized constriction and irregular caliber of the capillaries were evident in the vascular casts. Two layers of capillary network in the retina were maintained, but the capillaries were decreased in number. Numerous loop formations were present in the superficial capillary networks. Neither microaneurysms nor arteriovenous shunts were seen in young and old rats. Transmission electron microscopy revealed that capillary pericytes in the inner and outer plexiform layers had thickened basement membranes and that endothelial cells had many vesicles in their cytoplasm. Thus the retinal capillary changes in WBN/Kob rats are nondiabetic but due to hereditary retinal degeneration, although the systemic and pancreatic abnormalities in this rat strain are diabetic. Even when the retina becomes very thin, two layer capillary networks remain.

Lens and Retinal Changes in the WBN/Kob Rat (Spontaneously Diabetic Strain)

Male WBN/Kob rats represent a spontaneously diabetic strain with hyperglycemia, cataracts, nephropathy, neurophathy, pancreatic fibrosis and hyperlipemia. Cataracts and retinal changes in WBN/Kob rats were examined by light and electron microscopy to evaluate the ocular complications. Lens opacity was present in the posterior subcapsular and center of the anterior cortex of male 14-month-old WBN/Kob rats. Light and transmission electron microscopy showed swelling and irregularity of lens fibers. Scanning electron microscopy revealed that lens fibers were irregular and had many granules and bulging processes of various sizes on the cortical side of the opacified region. The nuclear side of the opacified region showed spongy changes and complete absence of lens fibers. Electron microscopy showed retinal degeneration in the photoreceptor outer segments of 1-month-old male WBN/Kob rats. Light microscopy showed thin outer segments and outer nuclear layers in 5-month-old rats, and electron microscopy revealed severe degeneration in the outer segments. The retinas of 11-month-old rats were thinner; the outer plexiform layer was very thin; the photoreceptor cell nuclei in the outer nuclear layer had decreased to one layer and were almost in contact with the inner nuclear layer nuclei, while the visual cells had disappeared. Retinal degeneration had progressed even further in 14-month-old rats, and very few photoreceptor cell nuclei remained. The retinal capillary lumens were small, and their pericytes had thickened basement membranes. The basement membranes of retinal capillaries from WBN/Kob rats were significantly thicker than those from control Wistar rats (p < 0.0001). Although this rat has spontaneous diabetic features, such as cataracts, its retinal changes look more degenerative.

Conjunctival swabs and corneoscleral rim cultures from corneal transplantation donors as possible early indicators for posttransplant endopthalmitis.

PurposeTo determine by microbiological examinations the rate of conjunctiva and corneoscleral rim contamination of cadaver donor tissues.MethodsA prospective review of culture results for 98 cadaver donor conjunctival swabs [mean age 76.4 ± 12.9 years (±SD)]. Transplant patients were evaluated both before and after disinfection with gentamicin. Individual parameters evaluated included detection rates of bacteria, variety of detected bacteria, time interval from donor death to tissue harvest and age of donors.ResultsBefore disinfection, 60 out of 98 conjunctival swabs exhibited microbial growth, while only 36 out of 98 exhibited growth after disinfection (p = 0.0006). Longer intervals between death and tissue harvest were associated with higher positive microbial growth rates. Prior to disinfection, culture-positive donors (74.1 ± 13.6 years) were significantly younger than culture-negative donors (79.8 ± 10.8 years) (p = 0.024). Positive donor rim cultures were noted in 2 out of the 22 corneal transplantations. Microorganisms isolated from the corneal grafts matched those found in the conjunctiva.ConclusionsIt is recommended that the corneoscleral buttons be removed as soon as possible. Cultures of conjunctival swabs collected from donors after disinfection may be useful in determining treatment for postoperative infections occurring after corneal transplantation.

The retinal pigment epithelium of Cr-deficient rats

The purpose of this study is to investigate the effect of Cr deficiency on the rat retina. Three-week-old Wistar Kyoto rats were divided into 2 groups. Cr-deficient rats were fed AIN-93G diet without Cr and deionized distilled water. Control rats were fed AIN-93G diet and deionized distilled water. The Cr and sugar concentrations in the whole blood and cholesterol concentration in the serum were measured. We observed the retina with an electron microscope, and counted phagocytized lamellar structures in the retinal pigment epithelium (RPE) before and after the start of light exposure on negative electron microscopic films. The whole blood Cr level of Cr-deficient rats was less than 0.2 microg/l. The blood sugar level of Cr-deficient rats was significantly higher than that of normal rats (p < 0.05). There were significantly more phagocytized lamellar structures in the RPE of Cr-deficient rats 1, 2, 7, 11 and 12 h after the start of light exposure than in that of normal rats (p < 0.05). However, no morphological abnormalities were found in the photoreceptor cells of Cr-deficient rats. Phagocytosis in the photoreceptor outer segment discs in the RPE was accelerated, but the pattern of the retinal circadian rhythm with maximum phagocytosis 2 h after exposure to light was unchanged. The Cr-deficient state may cause the membrane to degenerate, and phagocytosis of the photoreceptor outer segment discs in the RPE may be accelerated. This study provided an evidence of the nutritional importance of Cr in rat retina.

Choroidal Detachment After Vitreous Surgery

BACKGROUND AND OBJECTIVE To study the frequency and clinical features of choroidal detachment (CD) after vitreous surgery, because there have been no reports on this problem. PATIENTS AND METHODS We studied the clinical features of 14 patients (15 eyes) with CD from a total of 380 patients treated with vitrectomy at the Nagasaki University Hospital from January 1994 to August 1997. RESULTS The incidence of CD after vitreous surgery was 3.9% (15/380). The reasons for vitrectomy were 6 retinal detachments, 4 proliferative diabetic retinopathies, and 5 others. During vitrectomy, 4 eyes were treated with scleral buckling, 11 with endolaser photocoagulation, and 3 with cryoretinopexy. Retinal detachment as a postoperative complication was seen in 8 patients, and in 5 of them the retina remained detached after the final treatment. CONCLUSIONS CD may be caused by scleral buckling, panphotocoagulation, or stress on the ciliary body. Some patients with CD have a poor outcome.

Transcorneal three-port vitrectomy without conjunctival incision.

We treated ERM in 7 eyes of 7 patients (female:male, 4:3; age, 39–77 years; mean, 66.1 years) between January 2005 and February 2007. A giant bleb developed in one patient after trabeculectomy. Phacoemulsification with a corneal incision was followed by continuous curvilinear capsulorhexis of the posterior capsule (Figure 1A). Three side-port limbal incisions weremade using a 23-gaugeV-lance (MANI, Utsunomiya, Japan) (MANI, Utsunomiya, Japan) at 9:30 o’clock, 2:30 o’clock, and 4 o’clock or 8 o’clock (at a temporal lower site) clock positions. We also performed 25-gauge transcorneal vitrectomy using a notched contact lens (Figure 1B) (which we made 3 cuts at the edge of a disposable silicon lens using a straight knife) and core vitrectomy and ERM peeling (Figure 1C). We inserted the intraocular lens into the capsular bag after vitrectomy (Figure 1D).