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A case of polyarteritis nodosa complicated by left central retinal artery occlusion, ischemic optic neuropathy, and retinal vasculitis.

A 23-year-old single female patient developed constitutional manifestations in the form of fever, weight loss, anorexia, malaise, fatigue, and generalized aches in January 1995, 2 weeks after an attack of German measles. This was followed by painful, reddish, macular skin lesions over both legs which healed by dark pigmentation (leucocytoclastic vasculitis), mononeuritis multiplex, and Raynaud's phenomena of both hands and feet. Angiography of lower limbs was done to visualize the arterial tree of both lower limbs and revealed typical beading of distal arterial branches, a diagnosis compatible with polyarteritis nodosa (PAN). At that time, the patient received prednisone (45 mg/day) and azatioprin (100 mg/day) and responded well to treatment. In a second presentation in June 2005, the patient developed sudden attack of loss of vision in her left eye. Ophthalmological examination of the patient revealed evidence of left central retinal artery occlusion, ischemic optic neuropathy. The patient received methyl prednisolone, 1 g IV infusion, daily infusion for three consecutive days followed by oral prednisolone, 30 mg/day. The patient received pulse cyclophosphamide IV infusion (0.6 g/m2) on the fourth day. One week after receiving therapy, the patient progressed from having light perception to counting of fingers from a distance of 1 m.

Adult↗

Noncovalent occupancy of the retinal-binding pocket of opsin diminishes bleaching adaptation of retinal cones.

Bright light bleaches visual pigment and leads to a persistent desensitization of isolated rod and cone photoreceptors called bleaching adaptation. Bleaching adaptation results from the combined effects of pigment depletion and adaptational modulation of certain cellular reactions in the visual transduction cascade. Here, we present evidence that in solitary cone photoreceptors isolated from the salamander retina, the latter effect is due to the presence of free opsin in the outer segment. Also, we demonstrate that this "opsin adaptation" can be reversed by treating the cells with synthetic retinoids similar to 11-cis retinal but having polyene chains too short to form protonated Schiff base attachments to opsin.

Adaptation, Physiological↗

Theoretical estimation of retinal oxygenation during retinal detachment.

The aim of the present work was to simulate the oxygenation of the whole retina during different degrees of retinal detachment. A differential equation describing the oxygenation of the whole retina, at different degrees of detachment, was set up and solved numerically. The results show that the choroid can supply the outer retina with a fairly large amount of oxygen as long as the detachment height is lower than about 1mm. This study thus supports the view that hyperoxia may well prove to be clinically beneficial.

Choroid↗

Evaluation of an immortalized retinal endothelial cell line as an in vitro model for drug transport studies across the blood-retinal barrier.

PURPOSE: To evaluate the growth and barrier properties of an immortalized rat retinal endothelial cell line (TR-iBRB) maintained on permeable membrane for drug transport studies. METHODS: TR-iBRB cells were grown on permeable membrane filters. The effect of coating material on cell growth was investigated. Transport of [14C]-3-O-methyl-D-glucose (3-OMG), AGN 194716, AGN 195127, AGN 197075, acebutolol, alprenolol, atenolol, brimonidine, carbamazepine epoxide (CBZ-E), metoprolol, nadolol, rhodamine 123, and sotalol was measured across the cultured cell layer to determine the apparent permeability coefficients (Papp). Rhodamine 123 uptake into these cells in the presence of these test compounds was evaluated. Western blot was performed to detect the efflux transporter P-glycoprotein (P-gp). Bidirectional transport in MDR1-MDCK cell monolayers overexpressing the human P-gp was measured for AGN 197075. RESULTS: TR-iBRB cells form confluent cell layers when grown on fibronectin-coated membrane and exhibit characteristic spindle-shaped morphology. A good correlation between Papp and cLogD (pH 7.4) of the compounds tested was observed, except for 3-OMG, AGN 197075, and rhodamine 123, which are substrates of carrier-mediated transport systems such as P-gp and a glucose transporter (GLUT1). When grown on permeable membrane, TR-iBRB cells expressed functional P-gp and GLUT1. CONCLUSIONS: TR-iBRB cells, when grown on permeable membrane, provide a useful tool for predicting permeability across the BRB. The usefulness of this model for high-throughput screening and rank ordering of drug candidates intended for the back of the eye in treatment of ocular diseases needs further characterization upon correlation with in vivo data.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Retinal detachment and giant retinal tears in aniridia.

Clinical findings in aniridia may include corneal epitheliopathy, glaucoma, lens subluxation and cataract, and hypoplasia of the fovea and optic nerve. We report the occurrence of retinal detachment due to giant tears in four eyes of three children with aniridia. All eyes were buphthalmic and none had undergone lens or posterior segment surgery. All operated eyes underwent vitreolensectomy and silicone oil injection; useful vision was restored in two eyes. The pathogenesis and management of this previously unreported complication are discussed.

Aniridia↗

[Necessary visual information for restoring reading with a retinal implant in a blind patients with massive retinal degeneration of photoreceptors].

DEFINITION OF THE PROBLEM: Our goal is to determine the minimum of information necessary for elementary reading, using a retinal implant. This concerns particularly the fragmentation (pixellisation) of the presented image and its position in the visual field. Fragmentation corresponds to the number of electrodes available, the position of the image in the visual field is equivalent to the site of the implant on the retina. MATERIAL AND METHODS: 10 degrees x 10 degrees windows, containing isolated words or letters, were presented to six healthy subjects on a computer screen. A coupling between the computer and an eye tracker stabilizes these images in an area of the visual field. This coupling constantly corrects the position of the image on the screen according to the direction of gaze. RESULTS: 1) A rapid decrease of the performance is observed at a certain threshold of pixellisation, dependent on the eccentricity of presentation of the images. 2) In central vision, about 400 pixels are sufficient to recognize 80% of the four-letters words. At 10 degrees of eccentricity, about 1225 pixels are needed. 3) An acceptable comprehension of a text (identification of four words out of five), is impossible at eccentricities higher than 10 degrees 4) About 50 pixels are sufficient for a satisfactory recognition of isolated letters, independently of their eccentricity. CONCLUSION: These data validate the method of investigation and provide valuable indications regarding minimal visual requirements in prosthetic vision.

Blindness↗

Acute frosted retinal periphlebitis associated with cytomegalovirus retinitis.

The clinical picture of an acute frosted periphlebitis has been reported in a limited number of otherwise healthy patients, and in one case of human immunodeficiency virus (HIV) infection. The disease is usually bilateral and highly sensitive to steroids. The case of a 26-year-old, HIV-seropositive woman who developed unilateral diffuse perivenous sheathing in the course of recurrent cytomegalovirus retinitis is reported. The appearance of the retinovasculitis was identical to that described as an acute frosted periphlebitis, and the disease proved to be highly sensitive to a combined treatment of steroids and ganciclovir. The clinical findings in this case support the possibility that the appearance of an acute frosted periphlebitis can occur in response to several different stimuli, including cytomegalovirus.

AIDS-Related Opportunistic Infections↗

Experimental retinal branch vein occlusion in rhesus monkeys. II. Retinal blood flow studies.

Experimental branch vein occlusion by laser photocoagulation in the rhesus monkey leads to early, marked, and lasting reduction of blood flow to the affected retinal region. The radioactive microsphere method demonstrates this reduction of blood flow in both gamma counting and autoradiography. The reduction of flow becomes evident as early as 2 hours after occlusion and persists up to 1 week. The mechanism of the altered flow is discussed.

Animals↗

The retinal dopamine network alters the adaptational properties of retinal ganglion cells in the cat.

1. Single-unit extracellular recordings of optic tract fibers were used to study ganglion cell (GC) response properties of the intact cat eye before and after the intravitreal injection of haloperidol or SCH23390, dopamine-specific antagonists. Nearly all of the dopaminergic cells in the cat retina are amacrine cells (ACs); thus the dopamine antagonists are thought to primarily block the postsynaptic effects of these dopaminergic amacrine cells. All GCs encountered were subjected to a battery of receptive-field (RF) tests, including classification as X or Y, and as ON or OFF. 2. The effects of haloperidol were greatest in the light-adapted OFF-center pathways and especially in the OFF-center Y-cell. Within 30 min of haloperidol injection, both the spontaneous and light-evoked activity of the OFF-center Y-cell fell to zero, but when the same cell was exposed to lower levels of steady-state background illumination (scotopic levels), the response of the cell once again became robust. 3. OFF-Center Y-cells that had partially recovered from the drug effects and OFF-center X-cells recorded when the drug effect was maximal both possessed intensity-response curves that were shifted to the right of normal. 4. Recovery from the drug effects reflect supranormal responses after the initial response reductions and may be due to haloperidol's action on the dopamine autoreceptor. 5. Of the ON-center cells, only the Y-cells showed response alterations; possessing higher spontaneous activities and slightly reduced amplitudes to RF center (RFC) illumination. 6. The effects of SCH23390 paralleled those of haloperidol except that the onset was faster and the duration of the action of SCH23390 was much shorter, and no supranormal responses followed the initial effects. 7. Dark-adaptation functions of OFF-center GCs revealed a normal rod-cone shift; however, SCH23390 eliminated the rod-cone break, and threshold quickly fell to that of the rod mechanism. 8. The dopaminergic neurons of the cat retina appear to play an important role in regulating the activity of retinal OFF-center pathways in the photopically adapted eye, and one of its functions may be to control the relative contributions of the rod and cone systems to the response properties of light-adapted OFF-center GCs. 9. It is argued that dopamine is released in the light and enhances cone pathway activity, perhaps in the outer retina at bipolar and horizontal cells, and suppresses rod pathway activity, perhaps in the inner retina at amacrine cells.

Adaptation, Ocular↗

[Retinal detachment with retinal tears--clinical characteristics and surgical results].

The authors evaluate a group of 53 eyes of 52 patients operated on account of retinal detachment with an oral dialysis. The mean follow-up period was 35 months. There were 37 (70%) traumatic dialyses. They were in the temporal lower quadrant in 58%, in the nasal upper quadrant in 16%, temporal upper quadrant in 13% and in the nasal lower quadrant in 13%. There were 16 (30%) idiopathic dialyses, all with one exception in the temporal upper quadrant, they were in the lower temporal quadrant. 52 eyes were operated primarily cryosurgically, one eye by pars plana vitrectomy. After primary surgery the retina adhered completely in 94% eyes. On account of relapses of detachment 9.4% eyes were reoperated. At the end of the follow up the retina adhered completely in 94% eyes. Functional improvement or stabilization of vision was achieved in 78% eyes with traumatic tears and in 87% eyes with idiopathic tears. The authors confirmed the existence of two different clinical entities--traumatic and idiopathic oral dialysis which differ as to site and to a certain extent also the prognosis of the disease.

Adolescent↗

Studies on retinal and retinal pigment epithelial gene expression.

The 'completion' of the murine and human genomes and creation of high-density expressed sequence tag (EST) databases from multiple tissues and multiple species, coupled with the development of high-throughput expression profiling approaches such as microarrays and Serial Analysis of Gene Expression (SAGE), is making possible the in-depth analysis of gene expression patterns in health and disease to an extent that was not previously possible. Such new information is providing insight into normal function, and into how normal function is altered in disease. Efforts have begun, and are accelerating, in the application of expression profiling to the study of the retina and retinal pigment epithelium (RPE). In this chapter we will review progress in this area. We will also discuss technical issues that make expression studies of the RPE particularly challenging, and share our experience in methodological approaches to overcome these challenges.

Animals↗

Hyperosmolarity response of ocular standing potential as a clinical test for retinal pigment epithelium activity. Rhegmatogenous retinal detachment.

The hyperosmolarity response of the ocular standing potential was recorded in unilateral rhegmatogenous retinal detachment (8 eyes) and in the fellow 'healthy' eye (8 eyes). The hyperosmolarity response was greatly suppressed (M-4 SD: M and SD indicate respectively the mean and the standard deviation in normal subjects) in all affected eyes (p less than 0.005), and slightly abnormal in 2 fellow eyes. The L/D ratio was normal in 2 affected eyes and in all fellow eyes. The hyperosmolarity response in the affected eyes was still greatly suppressed 14 months after successful surgical treatment.

Adolescent↗

Treatment of retinal detachment due to macular holes without chorio-retinal lesions. A seven-year follow-up study.

For the treatment of retinal detachment arising from macular holes we do not apply cryotherapy, light-coagulation, or diathermy in the area of the macula. Our method involves merely the fixation of a silastic sponge of 14-17 mm length and 7.5 mm diameter at the posterior part of the eyeball corresponding to macula and along the meridian of 12-6 o'clock axis. The sponge is stretched and then fixed at both ends to the sclera away from the posterior pole. The stretching and fixation of the sponge creates the proper indentation which closes the macular hole. By avoiding energy application we obtain better visual acuity. The present paper describes the results we have had in the last 7 years exclusively using this technique.

Follow-Up Studies↗