Evidence of impaired anterior segment fibrinolytic activity in chronic uveitis

Purified homologous fibrinogen (2.4-9.4 mg) was injected intracamerally in cat eyes at approximate six months intervals for up to 30 months in order to assess, in vivo, the long-term impact of chronic uveitis on anterior segment fibrinolytic capability. Normal and acutely inflamed eyes responded with slow clotting, small clot formation and rapid lysis (2-3 days). Chronically inflamed eyes showed rapid clotting, larger clots and much slower lysis, with BCG-induced uveitis much slower than endotoxin-induced uveitis. Suppression of plasminogen activator levels within aqueous humor of chronically inflamed eyes was indicated, using modified fibrin plate methods. The normal balance between fibrinolysis and fibrinogenesis within tissues bounding the anterior chamber is apparently tilted in favor of the latter function when inflammation is prolonged.

The pathophysiology of the ocular microenvironment. I. Preliminary report on the possible involvement of copper in ocular inflammation

The concentration of copper [( Cu]) in the extracellular fluid compartments of rabbit eyes was found to increase approximately 30-fold during experimental uveitis, generally paralleling increases in [protein]. However, during the recovery phase the decrease in [Cu] lags behind the decrease in [protein] in some rabbits, suggesting the presence of abnormally high levels of non-protein-associated Cu. Intravitreal injection of CuSO4 (6 micrograms of Cu/eye) causes an inflammatory response and evidence of tissue damage. A better understanding of trace element metabolism is clearly required to further elucidate the mechanism of ocular inflammation and associated tissue damage.

Ocular fluorophotometric analysis

Artifacts related to the wave-spreading phenomenon of fluorescent structures within the eye interfere with interpretation of vitreous fluorophotometric data. A standardized protocol which minimizes such artifacts is desirable in order to reveal actual changes in vitreous fluorescence. We have devised a protocol which reduces artifacts of crystalline lens autofluorescence and "tailing" from both lens and retina by the subtraction of preinjection data from measurements taken one hour after intravenous injection of fluorescein. A method of calculation is presented, performed automatically when programmed into a computerized fluorophotometer. Distinctions among healthy subjects and different kinds of ocular pathology are sharper when artifacts are reduced and the data are normalized to plasma fluorescein concentration. Examples of data from subjects with diabetes and no retinopathy, hypertension, cystoid macular edema, panuveitis and pars planitis are presented.

Clinical evaluation of clobetasone butyrate eye drops in the treatment of anterior uveitis and its effects on intraocular pressure

Clobetasone butyrate has been formulated as a new steroid preparation of use in ophthalmology and has been compared with prednisolone phosphate and betamethasone phosphate in the treatment of anterior uveitis. The results from 4 double-blind, between-patient studies have shown that all 3 treatments are effective in reducing the signs and symptoms of this intraocular disease. 87% of those patients receiving clobetasone butyrate had a good or satisfactory response, but no differences in therapeutic efficacy were observed between these 3 steroid treatments. Clobetasone butyrate had little effect on intraocular pressure when compared with dexamethasone or hydrocortisone, both of which cause a significant rise in intraocular pressure.

Physiopathology of Fuchs's heterochromic cyclitis

The aetiopathogenesis of Fuchs's disease is still unknown. Recent findings indicate that the role of the sympathetic nervous system can be excluded and that the theory of heredodegeneration is a more probable explanation. A congenital predisposition to the disease which may possibly be related to some malformation of the iris vessels should be considered. This may explain why the disease is not always unilateral. The recent immunological anomalies found in the aqueous humour should be confirmed. Comparative studies of clinical, vascular, and immunological data could be of great interest in the future.

Electrophysiologic changes in chronic pars planitis

We studied 13 patients, six males and seven females, ranging in age from 14 to 53 years, with chronic pars planitis and a form of secondary retinal degeneration. All had experienced visual blurring but none had significant pain. Nine of the 13 had some disturbance in night vision. Visual acuity had decreased in three patients (in one because of cataract, in one because of cystoid macular degeneration, and for unknown reasons in the third), increased in two patients (because of improvement in cystoid macular edema), and remained stable in eight. There were electrophysiologic abnormalities, consisting of delayed B-wave implicit time, abnormal response to 30-Hz flicker, and reduced B-wave oscillations, in almost every patient. Our finding suggested that pars planitis is a vitreoretinal disorder rather than an inflammatory disease of the uveal tract.

Endotoxin-induced uveitis in the rat

Experimental studies of ocular inflammation induced by endotoxin have been performed almost exclusively in rabbits. Although the rat has been considered refractory to both the systemic and local effects of endotoxin, the present study has shown that intravitreal injection of endotoxin evoked a characteristic acute inflammatory response which was reproducible and dose-dependent. In addition, a consensual ocular response in the control eye occurred which was less severe but also dose-dependent. Preliminary investigations support the view that consensual responses of this nature may be mediated by a nervous reflex are mechanism. Sequential histological analysis revealed a marked polymorphonuclear cell infiltration of most ocular tissues in the early stages, while mononuclear cells predominated after 3 days. Widespread intravascular microthrombi were also observed, particularly in the ciliary vessels. Recovery, however, was usually complete by 7 days.

Immunocompetence and transfer factor therapy in uveitis

A study of the clinical course of 20 patients with uveitis treated with transfer factor is reported. Twelve (60%) of the patients were initially immunoincompetent on screening. Eight of the 12 changed to an immunocompetent status after treatment and could either decrease or discontinue their anti-inflammatory drugs. Five had a statistically significant improvement in visual acuity. One of the 8 initially immunocompetent patients had a statistically significant visual improvement, and 2 decreased or discontinued all drugs, while 3 increased their drugs.

[Electro-ophthalmological responses in inflammations of various sections of the orbital visual pathways (author's transl)]

In a study of electro-ophthalmological responses of the EOG, the photopic and scotopic ERG, the OP and the VECP, in combination with fluorescein angiography and computerized perimetry, in 34 patients suffering from uveitis, chorioretinitis (lesions near the macula and at the periphery), papillitis or retrobulbar neuritis, the following results were obtained: Uveitis and chorioretinitis with lesions either near the macula or at the retinal periphery produce different responses; generally, pathologic responses of the EOG and ERG and normal VECP are obtained in cases of uveitis. Peripheral chorioretinal lesions lead to a diminution of the scotopic ERG, OP and EOG, in contrast to lesions near the macula, in which pathologically diminished amplitudes of the photopic ERG and VECP are found. In papillitis and retrobulbar neuritis, however, the most important peculiarity is the increase in latency and the decrease in amplitudes of the VECP, especially in retrobulbar neuritis.

Lysophosphatidyl choline in the aqueous humour during ocular inflammation

Phospholipase A and lysophosphatidyl choline (LPC) have been shown to induce significant changes in the lens permeability in vitro to cations and soluble proteins. During uveal inflammation, in various experimental models and in man as well, the levels of LPC in the aqueous humour have been shown to reach values which are harmful to the lens in vitro. In addition, a phospholipase is thought to be activated during the antigen + antibody + complement sequence. The possible significance of these findings is discussed in relation to the pathogenesis of complicated cataracts in uveitis and the possible role of the lens as a source of autoantigens in recurrent uveitis.

The role of prostaglandins in experimental ocular inflammations

Intraocular inflammations (uveitis) were produced in rabbits by intravitreal injection of killed and dried Mycobacterium butyricum or E. coli endotoxin, or paracentesis of the anterior chamber. The increase in permeability of the blood-aqueous barrier and the leucocyte migration into the aqueous humor were observed after these stimuli, although the leucocyte did not migrate after paracentesis. Topically applied indomethacin reduced these inflammatory parameters in the latter two models. However, ththacin, though the leucocyte was not affected by indomethacin, though the leucocyte migration was reduced. On the other hand, prostaglandin-like substances in thces of these substances were detected in the former model. These results indicated that, unlike the increase in the permeability of the blood-aqueous barrier after endotoxin injection andparacentesis, the response after M. butyricum injection is not mediated by prostaglandins. The role of prostaglandins in the leucocyte migration in these ocular inflammations was also discussed.

Chemotactic activity and cellular infiltration of aqueous humor in experimental herpes simplex uveitis

The degree of chemotactic activity of the aqueous humor for a specific type of inflammatory cell is in direct proportion to the extent of such cells infiltrating the aqueous humor of rabbits with either primary or secondary experimental herpes simplex uveitis. Chemotaxis may thus be a contributing factor in the pathogenesis of herpetic uveitis.

The structural basis of altered vascular permeability following intraocular inflammation

An immunogenic uveitis was produced in rabbits by the intravitreal injection of bovine gamma-globulin. Four to six months later, an alteration in vascular permeability was determined by greater accumulation of iodinated I 125 serum albumin in the previously inflamed eye than in the normal eye. An altered vascular permeability was found only in eyes with profound structural changes. Possible sites of extravascular protein leakage were: (1) proliferated blood vessels in the posterior chamber and vitreous; and (2) leakage through the disrupted and scarred ciliary epithelium. In eyes without evidence of altered vascular permeability, a persistent chronic inflammation was observed, and gliosis and chorioretinal scarring was prominent.

Serum obstruction of aqueous outflow in enucleated eyes

We perfused enucleated human eyes via the anterior chamber by the constant pressure technique. Infusion of human serum into the anterior chamber of enucleated human eyes for 30 minutes at 23 mm Hg pressure induced a 42% decrease in facility of outflow, which was not relieved by irrigation of the anterior chamber with balanced salt solution or alpha-chymotrypsin. Diluted serum also reduced the facility of outflow. Measured in a glass viscometer, diluted serum had less viscosity than undiluted, but interfered with outflow from the eye more than anticipated on the basis of viscosity alone. When we used lens depression to induce tension on the iridocorneal angle to simulate the effects of contraction of the ciliary muscle, outflow facility increased in control eyes that had not been exposed to serum and in serum-perfused eyes. However, the partial obstruction to outflow that had been induced by serum persisted. Normal serum components may become adsorbed or entrapped in the aqueous outflow system so as to obstruct outflow, and this may result in secondary glaucoma in eyes with chronic uveitis.

[ERG in Behçet's disease (author's transl)]

Rod- and cone-system electroretinograms from 16 patients suffering of recurrent posterior uveitis and one or more symptoms of Behçet's disease were studied. On the basis of an evaluation of the clinical picture and of the progression three stages of the disease were distinguished. These stages were compared to the changes in amplitude of the b-waves of the ERGs (Fig 1). The findings in this group of patients were also compared to those from 11 patients with "simple" posterior uveitis (Fig. 2). The electroretinographic results in both these groups were highly similar: in all patients progression of the ocular disease was accompanied by parallel reduction in amplitude of the b-wave of the ERG. All ERG responses were affected in a similar way: the rod-system was in general more severly affected than the cone-system in both groups of patients. On the basis of these data it appears that the ERG indicates the stage of retinal damage in posterior uveitis. However, we could not detect ERG changes characteristic for the Behçet type of uveitis.