A novel test for evaluating horses' spontaneous visual attention is predictive of attention in operant learning tasks.

Attention is described as the ability to process selectively one aspect of the environment over others. In this study, we characterized horses' spontaneous attention by designing a novel visual attention test (VAT) that is easy to apply in the animal's home environment. The test was repeated over three consecutive days and repeated again 6 months later in order to assess inter-individual variations and intra-individual stability. Different patterns of attention have been revealed: 'overall' attention when the horse merely gazed at the stimulus and 'fixed' attention characterized by fixity and orientation of at least the visual and auditory organs towards the stimulus. The individual attention characteristics remained consistent over time (after 6 months, Spearman correlation test, P < 0.05). The validity of this novel test as a predictor of individual attentional skills was assessed by comparing the results, for the same horses, with those obtained in both a 'classical' experimental attention test the 'five-choice serial reaction time task' (5-CSRTT) and a work situation (lunge working context). Our results revealed that (i) individual variations remained consistent across tests and (ii) the VAT attention measures were not only predictive of attentional skills but also of learning abilities. Differences appeared however between the first day of testing and the following test days: attention structure on the second day was predictive of learning abilities, attention performances in the 5-CSRRT and at work. The VAT appears as a promising easy-to-use tool to assess animals' attention characteristics and the impact of different factors of variation on attention.

[Cannabis and psychosis: search of a causal link through a critical and systematic review]. / Cannabis et psychose: recherche d'un lien de causalité à partir d'une revue critique systématique de la littérature.

INTRODUCTION: Although cannabis use may be involved in the aetiology of acute psychosis, there has been considerable debate about the association observed between cannabis use and chronic psychosis. In particular, because of the frequent co-occurrence between schizophrenia and cannabis use, the question has been raised of a causal link between exposure to cannabis as a risk factor and the development of psychosis or psychotic symptoms. OBJECTIVE: The aim of this article was to examine the evidence that cannabis use causes chronic psychotic disorders by using established criteria of causality. These criteria were defined by: biologic plausibility, strength of the interaction between the risk factor and the disease, reprieability of the results, temporal sequence between the exposure to the risk factor and the beginning of the disease and existence of a dose-effect relationship. METHODS: The selected studies were found in Medline using the keywords "cannabis" and "psychosis", "cannabis" and "schizophrenia", "cannabis" and "psychotic symptoms" and "prospective" or "cohort" or "longitudinal". The selected studies were all prospective studies assessing the temporal sequence between cannabis use and emergence of psychosis or psychotic symptoms. The search strategies resulted in 60 records that were screened by reading both titles and abstracts. Seventeen studies were considered eligible, and then, after reading the full text, seven met the inclusion criteria. RESULTS: Together, the seven studies were all prospective cohorts and represented 50,275 human subjects. There were three European studies (from Sweden, Holland and Germany), one from New Zealand and one from Australia. Only one study of the seven did not show a significant association between cannabis consumption and increase of the risk of developing a psychosis. However, this study had some bias, such as low level of cannabis use and the lack of evaluation of cannabis use after inclusion. For the six other studies, data show the existence of a significant association between cannabis use and psychotic disorders (with an increased risk between 1.2 and 2.8 in Zammit et al.'s study), particularly among vulnerable individuals (that is with a prepsychotic state at the time of inclusion). Therefore, all the studies that assessed a dose-effect relationship showed this link between cannabis use and the emergence of psychosis or psychotic symptoms. The fact that all causal criteria were present in the studies suggests that cannabis use may be an independent risk factor for the development of psychosis. Results seem to be more consistent for vulnerable individuals with the hypothesis that cannabis use may precipitate psychosis, notably among vulnerable subjects. In particular, early onset of cannabis use during adolescence should be an environmental stressor that interacts with a genetic predisposition to induce a psychotic disorder. CONCLUSION: The objective of this article was to examine whether cannabis use can be an independent risk factor for chronic psychotic disorders, by using established criteria of causality. Data extracted from the selected studies showed that cannabis use may be an independent risk factor for the development of psychotic disorders. Early screening of the vulnerability to psychotic disorder should permit improved focus on prevention and information about the specific risks related to cannabis use among this population.

Postural effect on manual laterality in different tasks in captive grey-cheeked mangabey (Lophocebus albigena).

The authors examined the effects of task complexity and posture on laterality and compared lateralization during different tasks in 9 captive grey-cheeked mangabeys (Lophocebus albigena) during spontaneous food processing and 3 experimental tasks. Comparisons with data of red-capped mangabeys (Cercocebus torquatus torquatus; semiterrestrial species) were used. Less than half the monkeys were lateralized for simple everyday activities, but 6 were lateralized for complex daily activities. Moreover, all the monkeys were lateralized when performing experimental tasks. Laterality at the group level was found for the bipedal task: Mangabeys were right-handed. Complexity of tasks increases laterality at the individual level. Significant differences between the 2 species of mangabeys were found, allowing us to confirm that postural constraints are a major factor in the emergence of group handedness.

Optic nerve head drusen. High-resolution computed tomographic approach.

Optic nerve head drusen are rare, inherited concretions, which are almost always calcified; their appearance must be known because they represent one of the major causes of pseudopapilledema. The computed tomographic (CT) scan can show small and buried drusen, which are sometimes difficult to diagnose by the ophthalmoscopic examination. Four cases of drusen (two bilateral and two unilateral) were confirmed or diagnosed by high-resolution CT. The CT appearance of drusen is characteristic because the calcifications are well defined, punctate, and strictly located in the optic disc. The use of high-resolution CT scanners is very helpful.

Immunological analysis of the aqueous humour in candida endophthalmitis. I: Experimental study.

An immunological study of aqueous humour and serum was carried out in experimental ocular candidosis in rabbits. Anti-candida antibody titres, immunoglobulin G, and albumin levels were evaluated in the aqueous humour and in the serum. A local synthesis of anti-candida antibodies was detected in numerous rabbits at the height of clinical activity of the lesions.

Immunological analysis of the aqueous humour in candida endophthalmitis. II: Clinical study.

An anterior chamber paracentesis was carried out on six patients with candida endophthalmitis and on control subjects. We endeavoured to find out if there was local production of antibodies by evaluating the anti-candida antibody titres, the immunoglobulin G, and the albumin levels in the aqueous humour and in the serum. A significant difference in the level of specific antibodies between patients and controls was found. Local synthesis of anti-candida antibodies was discovered in five out of six patients with candida endophthalmitis. There would seem to be a correlation between the severity of uveitis and antibody titres.

[Local production of specific antibodies in the aqueous humor in experimental Candida endophthalmia in rabbits]. / Etude de la production locale d'anticorps spécifiques dans l'humeur aqueuse dans l'endophtalmie expérimentale à Candida du lapin.

An increasing frequency of ocular lesions due to Candida albicans has been reported, but clinical detection of lesions, which may cause permanent blindness, remains difficult. Hematogenous endophthalmitis caused by Candida albicans in the rabbit is a useful model to study the pathogenesis of the disease, and perhaps to find new methods of biological diagnosis. A suspension of Candida albicans was injected in 15 rabbits, according to the method described by Edwards et al. In 1975, causing uni or bilateral chorioretinitis in 12 of them. Unaffected eyes were chosen as controls. After aspiration of the anterior chamber fluid, serum and aqueous humour titres of specific antibodies were determined. A local synthesis of IgG antibodies was detected, after comparison of the titres of specific antibodies in the aqueous humour and in the serum, related to the serum and aqueous humour concentrations of IgG antibodies. According to a formula proposed by Witmer and Desmonts in ocular lesions due to different pathological agents, we calculated the "C" coefficient: C = antibody titres aqueous humor/serum x IgG serum/aqueous humor. A local synthesis of specific antibodies in cases of experimental endophthalmitis leads us to believe that aqueous humour aspiration could be used in the diagnosis of endophthalmitis in humans.

[Value of adjustable sutures in the treatment of diplopia]. / L'intérêt des sutures ajustables dans le traitement de la diplopie.

Adjustable sutures have been used as a curative procedure in 31 cases of diplopia, 16 cases of plegic causes, 4 cases of acute concomitant squint and 11 cases of mechanical strabismus: thyroid myopathy, orbital fracture, oculomotor imbalance after scleral indentation. In oculomotor paralysis if a few functional motor units remained at plegic muscle level, we were able to obtain new rotational balance by combining, with adjustable sutures, recession and resection of the couple agonist-antagonist. On the other hand, if no functional motor unit remained, it was then necessary to turn to the muscular translocation process modulated by adjustable surgery. In acute concomitant strabismus, adjustable retroposition of the medial rectus enabled us to fall back into an area controlled by fusional vergencies. Lastly, in mechanical strabismus by passive limitation, adjustable sutures usually enabled hyperaction of the contralateral synergists to be controlled and to bind a new rotational balance, compatible with a simple binocular field of vision. The advantage of this technique was to adapt, on adjustment, the motor response to the new innervational background which had disappeared under anaesthesia.

[Hemorrhage in the vitreous and retinal venous loop in a diabetic subject]. / Hémorragie du vitré et boucle veineuse rétinienne chez un sujet diabétique.

A vitrectomy was performed in a diabetic patient because of unilateral vitreous hemorrhage, which persisted for six months. There was only background retinopathy in the other eye. In the operated eye, no proliferative retinopathy was found. During surgery a partial posterior vitreous detachment was noted with persistent vitreoretinal attachment to the superotemporal vascular arcade. Postoperative fundus examination and fluorescein angiography showed background retinopathy and the presence of a venous loop involving the superotemporal vein. Histologic description of venous loops with vitreoretinal adhesion was recently reported and it was suggested that this could lead to vitreous hemorrhage even in absence of severe proliferative retinopathy. To our knowledge, there is no previous report of diabetic vitreous hemorrhage probably due to a venous loop with vitreoretinal attachment.

[Renewed peripheral sub-retinal vascularization and its pathological consequences (author's transl)]. / La néovascularisation sous-rétinienne périphérique et ses conséquences pathologiques.

The existence of renewed peripheral sub-retinal vascularization has been known for some time, but it has not attracted the attention that it merits. It possesses similar features to that of renewed sub-retinal vascularization of the posterior pole, and the consequences of this condition are well known. Two clinical cases are reported in which clinical and angiographic investigations demonstrated this type of alteration. Histological examinations showed its continuity with the choriocapillary. It is possible, though still not conclusively demonstrated, that renewed peripheral sub-retinal vascularization plays an important role in peripheral retinal diseases such as serohemorrhagic detachments of the peripheral retinal degenerations.

[The frequency of alterations of the lipid and hydrocarbon levels in retinal detachment]. / Fréquence des altérations des bilans des lipides et des hydrates de carbone dans le décollement de la rétine.

The biological lipid levels and hyperglycaemia measured in patients of varying ages with retinal detachment have shown that:--in 59.7% there is a hyperlipaemia or hyperlipoproteinaemia. This is more usually a hyperpre-beta-lipoproteinaemia (37.1%);--in 32% a disturbance of lipid metabolism was associated with a disturbance of glucose metabolism: diabetes or a pre-diabetic state;--49% of patients affected with hyperlipidaemia present with a clinical vascular condition;--42% of all the patients present with a clinical vascular condition. The numbers are considerable and they show the frequency of atherogenic factors in retinal detachment.

[Possible vascular factor in idiopathic detachment of the retina (author's transl)]. / Recherche d'un facteur vasculaire au cours du décollement rétinien idiopathique (comparaison entre sujets myopes et non myopes).

The possible influence of a vascular factor in idiopathic detachment of the retina was studied by comparing the frequency of hypertension and hyperlipidemia in groups of myopic and non-myopic subjects within the age group 50 to 65 years. Hypertension was present in 37.1 p. cent and hyperlipidemia in 60 p. cent of the non-myopic subjects, against 9.7 p. cent and 33.33 p. cent respectively in the myopic subjects. These results, together with the fact that there was a later age of onset in the non-myopic group, suggest that a vascular factor could be of etiological significance in idiopathic detachment of the retina in non-myopic subjects.

[Changes in perimetric defects in chronic open-angle glaucoma studied by automated perimetry (Octopus)]. / Variations des déficits périmétriques dans le glaucome chronique à angle ouvert étudiés en périmètrie automatique (Octopus).

The Octopus automatic perimeter was used to determine changes in visual field of 90 patients with chronic open angle glaucoma. Mean sensitivity value calculated from 62 of the 73 points of the apparatus program 33 - after elimination of those 11 points corresponding to Mariottes's zone and the central 10 degrees - provides an effective paracentral visual field monitoring numerical parameter. The authors named the parameter "global value". Statistical analysis of "global value" variations between two successive examinations showed: significant improvement between the first and the second tests; disappearance of the phenomenon between two further successive tests. The reasons for this pseudo-improvement remain unclear: perhaps the patients experience gained from the precious tests plays a part in the phenomenon. This should in any case be taken into account when assessing possible aggravation between two tests. Analysis of results suggests that, as a standard evaluation method, any "global value" degradation of the order of 1 db between the first two tests and 3 db between two successive tests performed after the second one is significant of a visual field degradation with a 1% range of error.

[Maculopathy in typical retinitis pigmentosa apropos of 33 cases]. / La maculopathie dans la rétinopathie pigmentaire typique. A propos de 33 cas.

The authors studied 33 maculopathies in 54 patients affected by typic retinitis pigmentosa: atrophic macular degeneration 31 cases (49%); cystoïd macular oedema: 1 case (3%) and macular retraction syndrome: 1 case (3%). These results are confronted with those of the literature. Two therapeutical trials based on pathogenical hypothesis were conducted. The patient with cystoïd macular oedema was treated by Hyperbar oxygenotherapy, basing one of selves on the theory ischemia. Six other patients with atrophic foveolopathies were treated by the cyclophosphamide, according to the autoimmune theory. In the first trial, the result was positive. In the second one, the results did not permit any available conclusion.

[Argon laser trabeculoretraction in chronic open-angle glaucoma. Personal results based on 100 eyes]. / La trabéculorétraction par laser argon dans le glaucome chronique à angle ouvert. Résultats personnels sur 100 yeux.

Argon laser trabeculoplasty (or trabeculoretraction) was used following WISE's technique in 100 cases of open angle glaucoma. The patients, all of different ages, presented with various forms of open angle glaucoma. In some cases, the intraocular pressure had not been normalized by the medical treatment, and in some others, the patients showed drug intolerance. We eliminated the patients whose angle was too narrow to allow photocoagulation. They were examined at regular intervals of 1 week, 2 weeks, 1 month, 3 months, 6 months and 12 months after therapy. Pressure figures only were considered in the therapeutic follow-up. After 12 months, the mean pressure drop was 7.3 mmHg after 180 degrees trabeculoplasty and 11.43 mmHg after 360 degrees trabeculoplasty, the latter consequently entailing a more considerable drop. Older subjects however showed a greater pressure decrease. We obtained less satisfactory results in cases of exfoliative syndrome glaucoma and pigmentary glaucoma. The important point is that pressure normalization was obtained--in most cases--only if the prior medical treatment was maintained either without any change or lightly reduced. The trabeculoplasty alone reduced ocular pressure in only 3.57% and in 9.09% respectively after 180 degrees and 360 degrees trabeculoplasty. We can therefore conclude from these observations that this technique is only an auxiliary method in open angle glaucomas that do not sufficiently respond to medical treatment.

[An electronic visual aid using a luminance amplifier in night vision disorders]. / Aide visuelle électronique par amplificateur de luminance dans les altérations de la vision nocturne.

The efficiency of a light amplifier system for the improvement of night vision has been tested on 30 normal subjects and on subjects suffering from night blindness including 36 patients with pigmentary retinopathy, 18 myopic patients with night blindness and 12 patients with senile cataracts. In all cases, the scotopic vision presented a great improvement and it reached up to half of photopic vision. The use of the light amplifier would certainly provide a considerable improvement for subjects suffering from night blindness and mostly for those suffering from pigmentary retinopathy. But two conditions are necessary for this: miniaturization of the device and absence of major macular lesions in the patient.

[Effect on pressure after instillation of a drop of depot-pilocarpine. Clinical results of its medium-term action]. / Effet tensionnel après instillation d'une goutte de pilocarpine retard. Résultats cliniques de son action à moyen terme.

A clinical comparison of an emulsion containing a new pilocarpine polymer (Polym) compound to that of a traditional pilocarpine salt solution (Plc) on the intraocular pressure (IOP) has been performed in 40 open-angle patients treated with the long acting pilocarpine-complex for 120 days. The treatment protocol was divided into 3 stages: Stage 1 is a single dose treatment where 12 patients were divided randomly into 2 groups of 6 each. The patients of each group were given 1 drop into each eye: 1 drop every 12 hours for Polym, 1 drop every 6 hours for Plc. The patients were observed for a period of 24 hours. After 24 hours without medication, the treatments were crossed over and nycthemeral graph curves were registered for both groups. Stage 2 is a medium term study were the 12 patients used in Stage 1 were added to another 28 patients. All 40 were then assigned to 1 of 2 treatment groups (2 groups of 20 patients each) according to a table of random numbers. Treatments were administered during one month, then cross-overed again during 4 weeks. Stage 3: finally, every patient could choose his treatment (either Polym or Plc) for the rest of the period (2 months). The clinical study shows that the polymer complex (Polym) produced a prolonged therapeutic effect, this being consistant with a slow release pattern and maintained a more effective around-the-clock control than pilocarpine solution. These results were accomplished by two applications per day as compared to the four necessary applications of Plc, on a half daily pilocarpine dose with Polym. The medium term results confirmed the efficacity noted in the short term survey. Most patients preferred Polym to Plc when they were asked. Throughout the 4 months study period, no adverse side effects were reported. Visual disturbances characteristic of pilocarpine eye-drops were reduced from 3 times a day on pilocarpine salt solution to once a day on pilocarpine polymer complex.

[Superior bullous retinal detachment: value of the intravitreous injection of sulfur hexafluoride]. / Décollement de rétine bulleux supérieur: intérêt de l'injection intravitréenne d'hexafluorure de soufre.

15 cases of superior bullous hemi-retinal detachment were repaired during a 16-month period, with a post-operative follow-up of 3-19 months. Intravitreal injection of 0,75-1,5 cc of pure sulfur hexafluoride (SF 6) was performed in 9 cases. The indications for injection at the end of the procedure were: 1) absence of chorioretinal contact in spite of an indentation in the correct position; 2) fishmouth configuration of the retinal break; 3) presence of radial folds over an indentation parallel to the limbus. Only two out of patients required a second operation, due to the development of proliferative vitreoretinopathy. One case was unsuccessful because of a redetachment secondary to massive periretinal proliferation. No complication was observed with the injection of SF 6. In particular, ocular hypertension was avoided by controlling the amount of gas used, always inferior to 2 cc, and postoperative treatment with acetazolamide and topical timolol. The intraocular injection of SF 6 appears to be useful contribution to the surgical treatment of superior bullous hemi-retinal detachment, allowing effective and durable internal tamponade, while avoiding prolonged bedrest.

[Optic neuropathy in acute poisoning with methanol]. / Neuropathies optiques au cours d'une intoxication aiguë par le méthanol.

The authors report four cases of methanol poisoning, two of which suffering acute bilateral optic neuropathy which secondarily leads to optic atrophy. The report the main clinical features of such a poisoning and the actual basis of its physiopathology and treatment. According to the four cases reported, they underline the importance of early diagnosis and specific treatment.

[Alleviation of ocular complications of the hyperviscosity syndrome in Waldenström's macroglobulinemia using plasma exchange]. / Amélioration des complications oculaires du syndrome d'hyperviscosité de la macroglobulinémie de Waldenström par les échanges plasmatiques.

Two patients presenting ocular complications of hyperviscosity syndrome in Waldenström's macroglobulinemia have been treated by plasmapheresis after inefficiency of immunosuppressive therapy. Plasma exchange seems an useful treatment as shown by clinic and angiographic improvement. In each case improvement of retinopathy was correlated with decrease of serum IgM level and blood viscosity measured by isotopic method. Fluorescein angiography, easily repeated, seems a very good method for following hyperviscosity syndrome in Waldenström's macroglobulinemia.