Time-of-flight secondary ion mass spectrometry can replace histochemistry demonstration of fatty acids in the retina.

PURPOSE: The purpose of this study was to demonstrate fatty acids in the rat retina and to show that time-of-flight secondary ion mass spectrometry (TOF-SIMS) can replace histochemistry. METHODS: Five normal 3-month-old Wistar Kyoto rats were used. The eyes were enucleated under pentobarbital anesthesia, immediately put into liquid nitrogen without any fixation, then cut into semithin sections, which were covered by OCT compound. Serial semithin sections were cut to 8- micro m thickness with a cryoultramicrotome and air-dried. They were placed on a silicon plate and air-dried for 1 h for analysis with TOF-SIMS. Before the specimens were analyzed, the molecular weight of the secondary ion for each molecular substance was measured with the use of commercial samples. These values were used for calculating the count of the secondary ion for each molecular substance. The molecular weights of the secondary ions of maleic acid, palmitic acid, oleic acid, stearic acid, arachidonic acid, and docosahexaenoic acid were determined in the photoreceptor cells. RESULTS: Of the fatty acids in the photoreceptor cells, maleic acid had the highest count, followed in descending order by palmitic, oleic, docosahexaenoic, stearic, and arachidonic acids. CONCLUSIONS: TOF-SIMS can demonstrate the presence of fatty acids in the retina, replacing histochemical techniques.

Riboflavin deficiency induces ocular surface damage.

PURPOSE: To examine the conjunctiva and cornea of riboflavin-deficient rats with scanning (SEM) and transmission (TEM) electron microscopes. MATERIALS AND METHODS: Three-week-old Wistar Kyoto rats were fed a riboflavin-deficient diet (0.05 mg riboflavin/100 g) for 3 months. As a recovery experiment, rats which had been on a riboflavin-deficient diet for 3 months were given water with 1 mg riboflavin/300 ml for 2 months. The conjunctiva and the cornea were examined with SEM and TEM. RESULTS: The serum riboflavin level was significantly lower in the riboflavin-deficient group than in the controls. In rats on a riboflavin-deficient diet for 3 months, SEM showed decreased microvilli and microplicae in the superficial epithelium of the conjunctiva and a decrease in the number of goblet cells. The cornea showed many dark cells and a marked decrease of microvilli and microplicae. In the riboflavin-deficient rats, TEM of the conjunctiva showed a decrease of microvilli and microplicae in the most superficial epithelial cells, a decrease in the layers of the epithelium and a marked decrease in the number of goblet cells, while the cornea had decreased microvilli and microplicae in the superficial epithelium, dark wing cells, loss of the basement membrane and hemidesmosomes of basal cells, cell debris and degenerative stroma cells and deposits of dense bodies in the subepithelial layer of the stroma. In rats recovered from riboflavin deficiency, the conjunctiva and cornea showed no abnormalities. DISCUSSION: Riboflavin plays a role in the development and maintenance of the surface structures of epithelial cells. Riboflavin may also be necessary for the development and maintenance of goblet cells. CONCLUSION: Riboflavin is essential for maintaining the structure and function of the ocular surface.

Ocular surface in Zn-deficient rats.

PURPOSE: We studied the cornea and conjunctiva of Zn-deficient rats with an electron microscope and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to elucidate the role of trace elements in the cornea and conjunctiva. MATERIALS AND METHODS: Twenty-one-day-old Wistar Kyoto rats were fed a Zn-deficient diet and deionized water for 7 weeks and then killed. The control rats were fed a Zn-deficient diet and deionized water supplemented with 3 mg Zn/100 ml. After 7 weeks on the deficient diet, another group of rats was given drinking water containing 3 mg Zn/100 ml and the usual diet containing 4.7 mg Zn/100 g for 8 weeks for recovery. The cornea and conjunctiva were examined by electron microscopy and TOF-SIMS. RESULTS: Microvilli and microplicae in the most superficial layer of the epithelium of the Zn-deficient rat conjunctiva and cornea were prominently reduced, and dark cells were significantly increased. The numbers of goblet cells were decreased in the conjunctiva of the Zn-deficient group. Zn, Ca and Al ions were significantly fewer, but K, Fe, Cl and S ions were significantly more numerous in the Zn-deficient group than in the control group. In the cornea of the Zn-deficient group, there was significantly more Cl but less Ca and vitamin C than in the controls. DISCUSSION: Zn deficiency may interfere with protein, nucleic acid and collagen synthesis through the reduction of Zn-containing enzymes. Myosin-like substance, actin filaments and tonofibrils are important structural components for microvilli and microplicae in the epithelium. Maldevelopment of these structural components may be related to disturbed activities of Zn-containing enzymes in protein and collagen synthesis because of Zn deficiency. In addition, Zn deficiency caused changes in the levels of Zn and other trace elements such as Ca, Al, S, Fe, and Cl and vitamin C. CONCLUSION: Zn deficiency resulted in poorly developed microvilli and microplicae on the ocular surface tissues, reduced the number of goblet cells and changed the quantity of trace elements and vitamin C.

A case of uveal, palpebral, and orbital invasions in adult T-Cell leukemia.

BACKGROUND: Patients with adult T-cell leukemia (ATL) may have eyelid lymphoma, uveitis, or cytomegalovirus retinitis due to being immunocompromised. However, there have been few reports on the invasion of multiple ocular lesions. We treated 1 unusual ATL patient with uveitis in whom multiple ocular invasions were suspected. CASE: A woman in whom ATL was diagnosed 10 years previously complained of blurred vision and decreased visual acuity in the right eye. Anterior uveitis of the right eye was suspected. One week later the cells increased in the anterior chamber, and fibrin exudates and hyphema appeared. She was admitted to our hospital. OBSERVATIONS: The visual acuity was 0.04 in the right eye and finger-counting from 30 cm in the left. She was treated with systemic steroid therapy. Inflammation disappeared, but both eyelids became swollen and multiple ocular lesions appeared. She was given carcinostatic therapy once more and the mass lesions decreased. Mass lesions appeared in the iris and in the bulbar conjunctiva. Computed tomography and magnetic resonance imagining (MRI) showed that the mass lesions extended to the right orbit and both nasal cavities. MRI also demonstrated choroidal thickening in the left eye. CONCLUSION: This case documents that ATL cells may cause severe uveitis and invade multiple ocular tissues such as the iris, eyelid, choroids, and orbit.

Inhibition of experimental choroidal neovascularization by an anti-growth agent inhibiting vascular endothelial development.

PURPOSE: To determine whether FR118487, a recently developed angiogenesis inhibitor, affects experimental choroidal neovascularization (CNV) induced by laser photocoagulation in pigmented rats. METHODS: Focal laser photocoagulation (argon green 50 mW, 0.04 seconds, 200 microm) was applied to the retinochoroid of normal Brown Norway rats. Systemic administration of FR118487 (1.0 mg/kg body weight per day) with a mini-osmotic pump implanted in the subcutaneous tissue of the neck was started just after laser photocoagulation and continued for 2 weeks. Choroidal vascular casts were made 2 weeks after laser photocoagulation and were examined with a scanning electron microscope. CNV formation was divided into three grades and evaluated. RESULTS: Laser-induced CNV formation was significantly less in rats given FR118487 than in control rats. CNVs in rats treated with FR118487 were less well developed than in the controls. CONCLUSION: FR118487 inhibits the development of experimental CNV induced by photocoagulation in pigmented rats.

Light and electron microscopic findings in a patient with orbital myolipoma.

BACKGROUND: This report describes the pathology of myolipoma, which is a benign soft tissue tumor and is a very rare tumor of the orbit. METHODS: A 41-year-old woman complained of exopthalmos of her right eye. By MRI (magnetic resonance imaging) examination, the tumor (30x20 mm) was located in the extraconus of four recti muscles. A part of the tumor was excised and examined with both light and electron microscopes and immunohistochemically. RESULTS: Light microscopic inspection revealed the tumor was formed by spindle-shaped cells, which were adipocytes and smooth muscle. Electron microscopy showed the cytoplasm contained parallel filaments associated with fusiform densities. Immunohistochemical staining showed smooth muscle stained with SMA (smooth muscle actin). Angiomyolipoma was excluded by negative staining for HMB45, Melan A. CONCLUSION: To our knowledge, only one case of orbital myolipoma has been reported. The intimate relationship between the two cell types led us to conclude that the tumor was dimorphic and could be classified correctly as a myolipoma.

Elements and organic substances in epiretinal proliferative tissue excised during vitreous surgery: analysis by time-of-flight secondary-ion mass spectrometry.

We examined with time-of-flight secondary-ion mass spectrometry (TOF-SIMS) various substances in vitreous proliferative tissues excised from patients with proliferative diabetic retinopathy or proliferative vitreoretinopathy. Amounts of elements, vitamins and fatty acids were measured with TOF-SIMS and then the average ratio of the count of spattered ions of each element and organic substance to the total count of spattered ions was calculated. The average ratios of Fe, Ca, Al, Zn and Cu ion counts to the total count of spattered ions were significantly larger in proliferative diabetic retinopathy than in proliferative vitreoretinopathy. The average ratios of each of vitamin A fragment-1 and palmitic acid ion counts to the total count of spattered ions were significantly larger in proliferative diabetic retinopathy than in proliferative vitreoretinopathy. The fact that diabetic and non-diabetic preretinal proliferative tissues contain organic substances suggests that these proliferative tissues are derived from the retina, especially the deep retina, probably the photoreceptor cell and/or retinal pigment epithelium. The presence of Zn and Cu also suggest the same process. Diabetic proliferative tissues rich in organic substances are thought to grow more than do non-diabetic tissues, because vitamins A and E, and fatty acids are necessary for the maintenance of cell structure and the proliferation of tissue. Analysis of biological specimens by TOF-SIMS is expected to provide valuable information.

Two cases of uveitis with tubulointerstitial nephritis in HTLV-1 carriers.

BACKGROUND: Although the tubulointerstitial nephritis and uveitis (TINU) syndrome has been reported, there are only a few reports in the ophthalmological literature. The ocular findings usually appear later than the renal findings, and a renal biopsy is required for a definitive diagnosis. CASES: Case 1 was a 15-year-old Japanese girl who was a carrier of the human T lymphotropic virus, type 1 (HTLV-1). She had tubulointerstitial nephritis, anterior uveitis, posterior retinal edema in the right eye, and peripheral vasculitis OU. Case 2 was a 56-year-old Japanese woman who was also a carrier of HTLV-1. Previously she had been diagnosed with Graves' disease, anterior uveitis, and vitreous opacity. Several years later tubulointerstitial nephritis was diagnosed. OBSERVATIONS: In both patients interstitial nephritis was diagnosed and systemic steroid therapy was effective. CONCLUSIONS: It is difficult for ophthalmologists to diagnose the TINU syndrome because the renal biopsy is performed by a pediatrician or an internist. This may be why ophthalmologic descriptions are rare in cases of TINU syndrome, even though the ocular findings reported in the literature are characteristic. This is the first case report of TINU syndrome in patients with HTLV-1. Ophthalmologists should pay more attention to the uveitis in the TINU syndrome.

Corneal changes in magnesium-deficient rats.

PURPOSE: The purpose of the current study is to investigate the cornea in magnesium (Mg) deficiency and elucidate the local function of trace elements. METHODS: After delivery, mother Wistar Kyoto rats were fed a low Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The corneas were examined by electron microscopy at 6 weeks of age. RESULTS: In the Mg-deficient rats, serum Mg levels were significantly lower and calcium (Ca) levels higher than in the control rats. The corneas of Mg-deficient rats showed decreased microvilli and microplicae in the epithelial cells of the most superficial layer, increased mitochondria with abnormal shapes in the basal cells in the epithelium, condensed chromatin in the nuclei of the basal cells, and high density deposits and macrophage-like cells in the subepithelium of the stroma. Mg-deficient rats had pentagonal and square endothelial cells. CONCLUSION: Since Mg2+ has biologic functions including structural stabilization of protein, nucleic acids, and cell membranes, Mg deficiency may induce changes in the corneal surface and nuclei of corneal epithelial and endothelial cells. These disturbances may interfere with protection from infections, foreign bodies, dryness, and direct exposure to air. Thus, Mg is essential for the cornea to maintain normal structure and function.

Inhibition of experimental choroidal neovascularization by irsogladine, an anti-gastric ulcer agent.

PURPOSE: To determine whether irsogladine inhibits experimental choroidal neovascularization (CNV) induced by laser photocoagulation in pigmented rats. METHODS: Focal laser photocoagulation (argon green 50 mW, 0.04 s, 200 microm) was applied to the retinochoroid of normal Brown Norway rats. Oral administration of irsogladine (5 mg/kg/day or 50 mg/kg/day) was started 1 week before and continued for 2 weeks after laser photocoagulation. Choroidal vascular casts were made 2 weeks after laser photocoagulation and were examined with a scanning electron microscope (SEM). CNV formation was classified according to three grades and evaluated. RESULTS: Laser-induced CNV formation was significantly reduced in rats given 5 mg/kg/day (p < 0.01) or 50 mg/kg/day of irsogladine (p < 0.001). Administration of 50 mg/kg/day of irsogladine was more effective in preventing CNV formation than 5 mg/kg/day (p < 0.001). The development of the vascular bud was especially inhibited by 50 mg/kg/day of irsogladine (p < 0.001). CNVs in rats treated with 50 mg/kg/day of irsogladine looked less well developed than those in controls. There was no significant side effect of irsogladine. CONCLUSIONS: Irsogladine inhibits the development of experimental CNV induced by photocoagulation in pigmented rats.

Vitamin E prevents changes in the cornea and conjunctiva due to vitamin A deficiency.

PURPOSE: To determine whether vitamin E can prevent changes in the cornea and conjunctiva due to vitamin A deficiency. METHODS: Male infant rats from normal mothers were weaned at 20 days of age and divided into three groups: in group 1, A(-), rats were fed a vitamin A-deficient diet; in group 2, A(-)E(+), rats were fed a vitamin A-deficient diet and injected intraperitoneally with 15 mg of vitamin E per week; group 3 rats were normal controls. At 13 weeks of age, the corneal and conjunctival changes were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: SEM showed more fine microvilli and clear cells in the most superficial epithelial layer of the cornea and conjunctiva in A(-)E(+) rats than in that of A(-) rats. Numerous secretory granules were seen in the goblet cells of the conjunctiva of A(-)E(+) rats, but in A(-) rats there was a total absence of conjunctival goblet cells. TEM showed a severely keratinized corneal surface in A(-) rats. On the other hand, the corneas of A(-)E(+) rats were almost normal in appearance. The conjunctivae of A(-) rats had superficial epithelial keratinization, scarce goblet cells, and many keratohyalin granules in the epithelium and dark cells, while in the conjunctivae of A(-)E(+) rats there were numerous secretory granules in goblet cells and some dark cells. CONCLUSION: The present study suggests that vitamin E has a protective effect against the corneal and conjunctival damage caused by vitamin A deficiency.

Ultrastructure of the optic nerve in magnesium-deficient rats.

PURPOSE: The ultrastructure of the optic nerves in magnesium (Mg)-deficient rats was studied to elucidate the function of Mg. METHODS: After delivery, mother Wistar Kyoto rats were fed a low-Mg diet containing 0.1 mg Mg/100 g diet with all other nutrients and distilled and deionized water. Infant rats were suckled by their mothers for 21 days and then fed the same Mg-deficient diet. Control mother rats were fed commercial rat pellets containing 24 mg Mg/100 g diet and all other nutrients. The optic nerves were examined by electron microscopy at 6 weeks of age. RESULTS: In the Mg-deficient rats, serum Mg levels were significantly lower and calcium levels higher than in the control rats. Ultrastructural findings were: significantly fewer myelinated axons and significantly thinner myelin sheaths in the Mg-deficient rats than in the control and pair-fed controls, and more numerous unmyelinated axons. There were multifocal areas of destruction and necrosis in the optic nerve of Mg-deficient rats. CONCLUSIONS: This study suggests that the optic nerve needs Mg for the development and maintenance of its cell structure.

Role of apoptosis in eyelid development.

The upper and lower eyelids fuse together during development and then reseparate. The mechanism of reseparation of the eyelids is still unclear, although many reports agree that keratinization has a major role in lid separation. We applied apoptotic detection methods with ultrastructural features to examine the process of lid separation in rats. We confirmed that the eyelids fused on the 18th day of gestation. At this stage, cellular excrescences appeared from the external and conjunctival surfaces overlying the junctional zone, and the junctional zone consisted of epidermal cell clumps with wide intercellular spaces. From the 18th to the 20th day of gestation, many apoptotic cells appeared in the junctional zone and in the cellular excrescences. In these tissues, TUNEL-positive cells and immunohistochemically stained macrophages were found at this stage. We conclude that apoptosis may eliminate external and conjunctival cellular excrescences to make both surfaces smooth and continuous across the junctional zone. Apoptosis may also play a major role in providing space for proliferation of newly organized epidermal cells without wide intercellular spaces. Subsequent keratinization extends onto epidermal and conjunctival sides of the junctional zone until separation of the lids is complete.

Retinal changes in Otsuka long-evans Tokushima Fatty rats (spontaneously diabetic rat)--possibility of a new experimental model for diabetic retinopathy.

PURPOSE: To study retinal changes in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a spontaneously diabetic rat, and evaluate it as a possible new diabetic retinopathy model. METHODS: We examined the retinas of OLETF rats and Long-Evans Tokushima Otsuka (LETO) rats as controls under both a transmission electron microscope (TEM) and a scanning electron microscope (SEM). RESULTS: We detected higher blood sugar level in the OLETF rats than in the LETO rats beginning at 5 months of age. The inner nuclear layers of the retina decreased from 3-4 rows to 2 rows, whereas the photoreceptor cell nuclei decreased from 8 rows to 3-6 rows. Retinal pigment epithelial cells decreased in height, and basal infoldings were poorly developed. Retinal capillary basement membranes were significantly thicker in the OLETF rats than in the LETO rats, and endothelial cell damage was observed. The SEM of vascular corrosion casts of OLETF rats showed tortuosity, microaneurysms, and loop formations. CONCLUSIONS: The development of spontaneous hyperglycemia in OLETF rats was associated with alterations in retina ultrastructure. Changes were similar to those seen in diabetic retinopathy, but did not include either hemorrhages or exudates. The OLETF rat may be a useful animal model for the study of ocular complications in humans.

Interaction of zinc and vitamin A on the ocular surface.

PURPOSE: The purpose of this study was to assess morphologically the interaction between zinc and vitamin A in their effect on the ocular surface. METHODS: Three-week-old Wistar Kyoto rats were divided into five groups: group A(+) Zn(+) was fed a diet containing both vitamin A and Zn; group A(-) was fed a vitamin A-deficient diet; group A(-) Zn(+) was given a vitamin A-deficient diet and deionized distilled water with Zn; group Zn(-) and group Zn(-) A(+) were fed a Zn-deficient diet, whereby group Zn(-) A(+) received an intraperitoneal injection of vitamin A. Corneas and conjunctivas of each group were examined by electron microscopy. RESULTS: The corneas and conjunctivas of group A(-) demonstrated a decrease in the number of microvilli in the epithelium. The corneas and conjunctivas of group A(-) Zn(+) had a decrease in microvilli but more microvilli than those of group A(-). The corneas of group A(-) showed keratinization, but those of group A(-) Zn(+) showed no keratinization. In group Zn(-) the microvilli on the conjunctiva and cornea were sparse. Group Zn(-) A(+) had a decrease in microvilli but more microvilli than group Zn(-). The conjunctivas of group Zn(-) A(+) had more goblet cells with granules than did those of group Zn(-). CONCLUSION: These results suggest that a synergistic interaction exists between vitamin A and zinc for the maintenance of the corneal and conjunctival epithelium.

Natural course of experimental choroidal neovascularization: three-dimensional study with corrosion cast and scanning electron microscope.

OBJECTIVES: The details of the morphological features of choroidal neovascularization (CNV) remain unclear. The purpose of this study was to establish a CNV rat model and study the natural course of CNV using vascular casts and a scanning electron microscope (SEM). METHODS: Focal laser photocoagulation (argon green 50 mW, 0.04 s, 200 microm) was applied to Brown Norway pigmented rats. Choroidal vascular casts were prepared 1 and 3 days, 1 and 2 weeks, and 1, 3 and 6 months after laser photocoagulation. The choroidal casts were examined with a SEM. RESULTS: One day after photocoagulation, corrosion casts and SEM revealed complete defects of the choriocapillaris at the laser shot sites. One week after photocoagulation, small vascular buds originating from the damaged choriocapillaris were observed. Two weeks after photocoagulation, newly formed CNV originating from an individual laser burn was observed. One to three months after photocoagulation, these new vessels were connected to each other to form CNV networks. Six months later, some thin and atrophic vessels were observed in the CNV network. CONCLUSIONS: We succeeded in making fine corrosion casts of CNV formed by photocoagulation in pigmented rats and in demonstrating the details of CNV formation and regression. It is hoped that the results of this study will contribute to the development of a drug therapy for CNV and to the interpretation of diagnostic imaging of CNV in humans.

Retinal and choroidal vasculature in rats with spontaneous diabetes type 2 treated with the angiotensin-converting enzyme inhibitor cilazapril: corrosion cast and electron-microscopic study.

The long-term effects of the angiotensin-converting enzyme (ACE) inhibitor cilazapril on retinal and choroidal circulation in rats with spontaneous diabetes type 2 were assessed by corrosion casts, scanning electron microscopy (SEM) and transmission electron microscopy. One group of 20 male Otsuka Long-Evans Tokushima Fatty (OLETF) rats was treated with 10 mg/kg/day of cilazapril from 4 to 64 weeks of age, and 20 other OLETF rats received no treatment. A third group, 20 male Long-Evans Tokushima Otsuka (LETO) rats, served as age-matched controls. At regular intervals, the rats were weighed, and their blood glucose was measured. Before the experiment, their systolic blood pressure and total cholesterol level were determined. At 64 weeks of age, the OLETF rats weighed significantly less than the cilazapril-treated OLETF and the LETO rats (p < 0.0001). At the same age, 100% of the untreated OLETF rats had bilateral cataracts, while the lens was clear and no fundus abnormality was detected in the cilazapril-treated OLETF rats and the LETO rats. Cilazapril lowered systolic blood pressure to a nearly normal level, significantly prevented the increase in blood sugar and inhibited the increase in serum cholesterol in the OLETF rats throughout the treatment. In the 64-week-old OLETF rats without treatment, corrosion cast and SEM revealed diabetic retinal and choroidal vascular changes: tortuosity of the vessels, variations in caliber, narrowing of arteries, arterio-arteriolar anastomoses and hairpin loop formation in precapillary arterioles, sparse collecting venules in the choroid and marked capillary changes such as caliber irregularity, narrowing, tortuosity, loop formation and decreased capillaries, outpouching and microaneurysms. In the cilazapril-treated OLETF rats, these changes were markedly decreased to the level seen in the LETO rats, in which the retinal and choroidal blood vessels had a definite and fairly constant pattern and the capillaries were more regularly and densely arranged and had a remarkably uniform caliber. Our results show that the long-term administration of cilazapril before or from the initial onset significantly prevented the increase in blood sugar and inhibited the increases in serum cholesterol in OLETF rats throughout the treatment, lowered systolic arterial pressure to a nearly normal level and prevented diabetic ocular complications. The effects of cilazapril on the diabetic retinal and choroidal vasculature are described for the first time. SEM of corrosion casts is a valuable and easy technique for showing precisely and three-dimensionally the effects of some drugs on the vasculature.

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.

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.