Masanori Kado

The Role of the Vitreous in Diabetic Macular Edema

The authors assessed retrospectively clinical records of 76 patients (125 eyes) 60 years of age or older with diabetic retinopathy who had undergone a vitreous examination. The groups consisted of 105 eyes (63 patients) with macular edema and 20 eyes (13 patients) without macular edema. Vitreous studies were done using the El Bayadi-Kajiura lens to determine whether or not the posterior vitreous was attached to the retina in the macula. Twenty-one of 105 eyes (20.0%) in the edema group and 11 of 20 eyes (55.0%) in the no-edema group had a detached posterior vitreous. This difference was found to be statistically significant, indicating that diabetic cases without macular edema have a significantly higher rate of posterior vitreous detachment than those with macular edema. This study demonstrates that the vitreous may play a role in diabetic macular edema.

Posterior vitreous detachment induced by injection of plasmin and sulfur hexafluoride in the rabbit vitreous.

PURPOSE To investigate whether an injection of plasmin and sulfur hexafluoride (SF6) can induce posterior vitreous detachment (PVD) without vitrectomy. METHODS One eye each of 15 New Zealand white rabbits was assigned to one of three groups. Eyes in group 1 received a vitreous injection of 1 unit of human plasmin (0.1 mL reconstituted in balanced salt solution) and 0.5 mL of SF6; eyes in group 2 received a vitreous injection of plasmin alone; eyes in group 3 received a vitreous injection of SF6 alone. Seven days after injection, all animals were monitored electroretinographically and killed, and the eyes were enucleated. After fixation, scanning electron microscopy was performed. RESULTS In group 1 eyes, the retinal surface was smooth except for the vitreous base, which showed complete separation of the vitreous cortex from the retina, indicating PVD. In group 2 and 3 eyes, sparse collagen fibers remained on the retinal surface. CONCLUSION Vitreous injection of plasmin combined with SF6 can induce PVD without vitrectomy.

A review of 324 cases of idiopathic premacular gliosis

We reviewed the records of 324 patients (395 eyes) seen between 1973 and 1987 with a diagnosis of idiopathic premacular gliosis. Mean age of onset was 64.6 years, 189 (58.3%) were women, and all but six patients were white. Initial visual acuity was 20/40 or better in 214 eyes (54.2%), 20/50 to 20/100 in 136 eyes (34.4%), and poorer than 20/100 in 45 eyes (11.4%). Follow-up examinations were made in 214 eyes. After a mean follow-up period of 33.6 months, 106 (49.5%) of the 214 eyes maintained a visual acuity within one line of initial visual acuity, 28 (13.1%) were more than one line better, and 80 (37.4%) were poorer. Partial or complete posterior vitreous detachment was present in 303 (84.9%) of the 357 eyes undergoing vitreous study; 43 (14.2%) of these 303 eyes had partial vitreous detachment with vitreous adhesion to the macula. Cystoid macular edema was present on angiography in 77 (20.6%) of 373 eyes undergoing fluorescein angiography; 20 (26.0%) of these 77 eyes had partial posterior vitreous detachment with vitreous adhesion to the macula, whereas only 23 (7.8%) of the 296 eyes without cystoid macular edema had such vitreous adhesion (P less than .001). Other findings were myopia in 116 of 367 eyes (31.6%) (103, or 88.8%, of the myopic eyes had posterior vitreous detachment), and increased intraocular pressure in 56 of 324 eyes (17.3%).

Intravitreal injection of hyaluronidase cannot induce posterior vitreous detachment in the rabbit.

Purpose: To investigate whether intravitreal injection of hyaluronidase can induce posterior vitreous detachment (PVD) in the rabbit. Methods: One eye each of 12 New Zealand white rabbits received intravitreal injection via the pars plana of 20 iU of hyaluronidase (0.1 mL reconstituted in sterile balanced salt solution [BSS]) into the midvitreous cavity. The fellow eye of each rabbit received a vitreous injection of 0.1 mL of BSS. At 3 and 6 months after intravitreal injection, four and eight rabbits were killed, respectively, and the eyes were enucleated. After fixation, scanning electron microscopy was performed to study the vitreoretinal interface. Results: At 3 and 6 months after injection, scanning electron microscopy showed that the retinal surfaces in eyes that received either hyaluronidase or BSS were covered with vitreous collagen fibers. No eyes, even those that received hyaluronidase over a period of 6 months, had the smooth retinal surface consistent with a bare internal limiting lamina that suggests the development of PVD. Conclusion: Hyaluronidase cannot induce PVD in the rabbit over a 6‐month period after vitreous injection.

Posterior vitreous detachment following panretinal laser photocoagulation

A total of 30 eyes of 19 patients with type I diabetes, varying severity of retinopathy, and no posterior vitreous detachment (PVD) were studied clinically, and vitreous examination was performed by preset lens biomicroscopy. Follow-up was 4.0–7.5 years. A total of 15 eyes underwent panretinal laser photocoagulation (PRP) and 15 eyes were left untreated. The incidence of PVD was 8 of 15 (53%) after PRP and 1 of 15 (7%) in untreated eyes (P<0.02). Minimal vitreous hemorrhage occurred in 4 of 7 treated eyes (57%) that did not develop PVD and in only 2 of 8 (25%) that did. In treated eyes with no history of vitreous hemorrhage, the incidence of PVD was 6/9 (67%); in treated eyes with minimal vitreous hemorrhage at any time, it was 2/6 (33%). In treated eyes, the presence of Diabetic Retinopathy Study (DRS) high-risk characteristics was equally frequent in eyes that developed PVD as in those that did not. These data suggest that PVD occurs following PRP, independent of the severity of diabetic retinopathy or prior vitreous hemorrhage.

Variations of posterior vitreous detachment

AIMS To identify variations in posterior vitreous detachment (PVD) and establish a clinical classification system for PVD. METHODS 400 consecutive eyes were examined using biomicroscopy and vitreous photography and classified the PVD variations—complete PVD with collapse, complete PVD without collapse, partial PVD with thickened posterior vitreous cortex (TPVC), or partial PVD without TPVC. RESULTS In each PVD type, the most frequently seen ocular pathologies were as follows: in complete PVD with collapse (186 eyes), age related changes without vitreoretinal diseases (77 eyes, 41.4%) and high myopia (55 eyes, 29.6%); in complete PVD without collapse (39 eyes), uveitis (23 eyes, 59.0%) and central retinal vein occlusion (8 eyes, 20.5%); in partial PVD with TPVC (64 eyes), proliferative diabetic retinopathy (30 eyes, 46.9%); and in partial PVD without TPVC (111 eyes), age related changes without vitreoretinal diseases (62 eyes, 55.9%). This PVD categorisation was significantly associated with the prevalence of each vitreoretinal disease (p<0.0001, χ2 test on contingency table). CONCLUSIONS PVD variations can be classified into four types, which is clinically useful because each type corresponds well to specific vitreoretinal changes.

Role of the Vitreous in Branch Retinal Vein Occlusion

We analyzed the vitreous findings in 62 patients (62 eyes) with major branch retinal vein occlusion to determine whether vitreous examination was useful in predicting the development of retinal or disk neovascularization, or both. In 18 eyes with no or partial posterior vitreous detachment and large areas of capillary nonperfusion (5 disk diameters or more), ten eyes (55.6%) eventually developed neovascularization. Only three of the remaining 44 eyes (6.8%) developed neovascularization. The probability of this development was greater in eyes with no partial posterior vitreous detachment at the initial vitreous examination (P = .0177, Coxs regression analysis), and in those with large areas of nonperfusion (P = .0097, Coxs regression analysis).

Comparison of the prevalence of posterior vitreous detachment in whites and Japanese

The vitreous condition of healthy white (n = 551) and Japanese (n = 528) eyes were reviewed and compared with respect to the prevalence of posterior vitreous detachment (PVD) in the two groups. No white or Japanese patient 39 years of age or younger had PVD; the prevalence among those older than 39 increased with age in the fifth through the ninth decades, i.e., respectively, to 4%, 24%, 37% 59%, and 87% in the whites, and to 5%, 21%, 43%, 72%, and 82% in the Japanese. In none of these decades was there any significant difference between the prevalence of complete or partial PVD in the whites and the Japanese. This finding is significant because the vitreoretinal relationship influences the development and prognoses of the various vitreoretinal disorders.

Vitreous Changes and Macular Edema in Central Retinal Vein Occlusion

The condition of the posterior vitreous was determined in 56 eyes with central retinal vein occlusion (CRVO). Using a life-table analysis, it was studied in 56 eyes. The incidence of posterior vitreous detachment (PVD) in the CRVO eyes at the first vitreous examination did not differ significantly from that in 64 age-matched control eyes. However, the incidence of PVD in CRVO eyes increased from 39.3% at the first vitreous examination to 58.5% after 6 months, and to 69.6% 1 year from the examination. The incidence of PVD in CRVO eyes during follow-up was statistically higher than that of the controls (P = .009). The incidence of PVD after the first vitreous examination was significantly higher in eyes with hemorrhagic retinopathy than in eyes with venous stasis retinopathy (P = .04). In the 34 eyes with macular edema, the edema lasted significantly longer in those with vitreomacular attachment (VMA) at the first examination than in those without VMA at this time (P = .02). VMA may play an important role in the pathogenesis and chronicity of macular edema in CRVO.

Light and electron microscopic immunocytochemical study on the innervation of the pineal gland of the tree shrew (Tupaia glis), with special reference to peptidergic synaptic junctions with pinealocytes

Conventional and immunocytochemical, light- and electron-microscopic studies on the innervation of the pineal gland of the tree shrew (Tupaia glis) were made. Neuropeptide Y (NPY)-immunoreactive fibers, which were abundantly distributed in the gland, disappeared almost completely after superior cervical ganglionectomy, suggesting that these fibers are mostly postganglionic sympathetic fibers. By contrast, tyrosine hydroxylase (TH)-immunoreactive fibers, which were less numerous than NPY-fibers, remained in considerable numbers in ganglionectomized animals, indicating the innervation of TH-positive fibers from extrasympathetic sources. Bundles of substance P (SP)- or calcitonin gene-related peptide (CGRP)-immunoreactive fibers, entering the gland at its distal end, were left intact after ganglionectomy. SP-fibers were numerous, but CGRP-fibers were scarce in the gland. SP-immunoreactive fibers were myelinated and nonmyelinated, and were regarded as peripheral fibers because of the presence of a Schwann cell sheath. NPY- and SP-immunoreactive fibers and endings were mainly localized in the pineal parenchyma. NPY-immunoreactive endings synapsed frequently, and SP-positive ones did less frequently, with the cell bodies of pinealocytes. The results suggest that NPY and SP directly control the activity of pinealocytes. Sections stained for myelin showed that thick and less thick bundles of myelinated fibers entered the gland by way of the habenular and posterior commissures, respectively. Under the electron microscope, the bundles were found to contain also unmyelinated fibers. A considerable number of nerve endings synapsing with the cell bodies of pinealocytes remained in ganglionectomized animals; these endings were not immunoreactive for TH or SP. Such synaptic endings may be the terminals of commissural fibers.