Tensile-strained germanium microdisk electroluminescence

We report room temperature electroluminescence of tensile-strained germanium microdisks. The strain is transferred into the microdisks using silicon nitride stressors. Carrier injection is achieved with Schottky contacts on n-type doped germanium. We show that a biaxial tensile-strain up to 0.72% can be transferred by optimizing the carrier injection profile. The transferred strain is measured by the electroluminescence spectral red-shift and compared to finite element modeling. We discuss the impact of this strain level to achieve population inversion in germanium.

Synthesis and antioxidant efficiency of a new amphiphilic spin-trap derived from PBN and lipoic acid

The synthesis of a new amphiphilic antioxidant called PBNLP and derived from both alpha-phenyl-N-tert-butyl nitrone (PBN) and lipoic acid was described. Grafting a lactobionamide moiety onto the aromatic group of the PBN provided the water solubility of this compound. In vitro preliminary biological evaluations of its antioxidant capacity were performed using the KRL biological test based on free radical-induced hemolysis. The PBNLP induces a protection of erythrocytes against exogenous free radicals higher than that measured with lipoic acid or PBN alone or with lipoic acid or PBN derivatives in admixtures.

[The reproduction of the population in the seventeenth, eighteenth, and nineteenth centuries. Examples from France and Quebec]

This article examines the descendants of four cohorts of couples formed in the seventeenth and eighteenth centuries (two cohorts in two French mountain valleys and one on the Ile-d'Orléans in Quebec). The children are separated into four categories according to their fate (deceased while still unmarried, unknown fate, married but childless, "useful children"). "Useful children", a concept used in population genetics, are those who in turn bear children. In all three places, the useful children represent only from 26 to 31% of births. The study goes on to measure the contributions made by these couples to the next generation. In the mean, each couple gave birth to little over one useful child. But the contributions of couples turns out to be very unequal. Depending on the place, from 36 to 53% of couples left no useful children behind them, while a small minority of couples made an ample contribution to the next generation. The same measure is reproduced in the constitution of the next generation, thereby showing that inequality of couples in terms of reproduction is perpetuated.

[Oxidative stress and human disease. Current knowledge and perspectives for prevention]

DYNAMIC BALANCE: The antibiotic status of the human organism results from the dynamic balance between the antioxidant system and the production of reactive oxygen species. Oxidative stress occurs when this balance shifts in favor of pro-oxidants as can occur in several disease situations. ROS: Part of the oxygen used by cells is transformed into toxic metabolites, reactive oxygen species (ROS), which can be the cause or consequence of tissue and molecular disorders. Some of the most prominent diseases linked with oxidative stress include atherosclerosis, cancer, allergy, neurodegenerative diseases, Parkinson's disease. PERSPECTIVES FOR PREVENTION: Actions designed to prevent the environmental cause, such as eviction of a exposure to toxins or a change in eating habits, can be an effective means of reducing the lesions induced. Study of total antioxidant potential could be quite useful for detecting and monitoring environmental damage and for clinical follow-up. It could also help in determining, for each individual, the negative or positive development of a therapy on the anti-free radical action. Treatments must be personalized according to the tested response.

Impaired homocysteine metabolism and atherothrombotic disease

Based on recent retrospective, prospective, and experimental studies, mild to moderate elevation of fasting or postmethionine-load plasma homocysteine is accepted as an independent risk factor for cardiovascular disease and thrombosis in both men and women. Hyperhomocysteinemia results from an inhibition of the remethylation pathway or from an inhibition or a saturation of the transsulfuration pathway of homocysteine metabolism. The involvement of a high dietary intake of methionine-rich animal proteins has not yet been investigated and cannot be ruled out. However, folate deficiency, either associated or not associated with the thermolabile mutation of the N(5,10)-methylenetetrahydrofolate reductase, and vitamin B(6) deficiency, perhaps associated with cystathionine beta-synthase defects or with methionine excess, are believed to be major determinants of the increased risk of cardiovascular disease related to hyperhomocysteinemia. Recent experimental studies have suggested that moderately elevated homocysteine levels are a causal risk factor for atherothrombotic disease because they affect both the vascular wall structure and the blood coagulation system. The oxidant stress that results from impaired homocysteine metabolism, which modifies the intracellular redox status, might play a central role in the molecular mechanisms underlying moderate hyperhomocysteinemia-mediated vascular disorders. Because folate supplementation can efficiently reduce plasma homocysteine levels, both in the fasting state and after methionine loading, results from further prospective cohort studies and from on-going interventional trials will determine whether homocysteine-lowering therapies can contribute to the prevention and reduction of cardiovascular risk. Additionally, these studies will provide unequivocal arguments for the independent and causal relationship between hyperhomocysteinemia and atherothrombotic disease.

[Economical consequences of intestinal nematodes infection in pigs]

The studies wers carried out in ZZD Kolbacz on 14 sows. The experimental groups control and treated consisted of 7 sows each. The sows were treated with Dectomax - 1 ml/33 kg of body weight. The efficacy of sows treatment's was verified with the Wllis-Schlaaf and McMaster method. The studies indicate, that subclinical infection of intestinal nematodes could influence the swine production. The piglets from treated with Dectomax sows were infected in 8% only; when all piglets from non treated sows were infected with nematodes. From treated sows 0.8 more piglet were obtained and the weight gain of litter was after 6 weeks 24.4 kg higher comparing with the control group.

Folate deficiencies and cardiovascular pathologies

Although folates are widely distributed in foods, folate deficiencies may be more frequent than expected because their true availability may be impaired due to their lability under various food cooking and processing conditions. Folate deficiency is frequently observed in elderly people, smokers, alcoholics and oral contraceptive users. It is also associated with the mutation leading to the thermolabile variant of N5,10-methylenetetrahydrofolate reductase which is observed in about 10% of the population. In addition to the essential role of the intracellular pool of polyglutamates in de novo biosynthesis of deoxyribonucleotides which allow cell growth and division, the reduced and methylated form of folate, N5-methyltetrahydrofolate, is required for the remethylation of homocysteine to methionine. By inhibiting this remethylation pathway, folate deficiency induces homocysteine efflux into the circulation. Many studies have shown a negative correlation between plasma folate, particularly N5-methyltetrahydrofolate, and circulating homocysteine levels. In addition, folate deficiency is a major cause of hyperhomocysteinemia which is fully recognised as an independent risk factor for atherothrombosis. Epidemiological and recent experimental studies have demonstrated that folate deficiency might increase the risk of cardiovascular disease by increasing circulating homocysteine levels. Thus, the clinical efficiency of folate supplementation, especially N5-methyltetrahydrofolate, in reducing homocysteine-dependent cardiovascular risk should be evaluated.

Folic acid deficiency enhances oral contraceptive-induced platelet hyperactivity

In previous studies conducted in female rats and in women, oral contraceptives (OC) were found to induce a platelet hyperactivity that was related to an oxidative stress. Because cases of megaloblastic anemia have been reported to occur in women taking OC, these treatments are suspected of depleting folate stores. In the study presented herein, which was conducted in rats, we sought to determine the influence of dietary folic acid deficiency (FD) on the thrombogenicity of OC. Animals were fed for 6 weeks with either a folic acid-deficient diet (250 micrograms/kg folic acid) or a control diet (750 micrograms/kg). One-half of the animals in each group were treated with OC (ethinyl estradiol plus lynestrenol). FD and OC individually potentiated platelet aggregation in response to thrombin and ADP and the release and metabolism of arachidonic acid, in particular, the biosynthesis of thromboxane. These platelet activities were further enhanced in animals given both the folic acid-deficient diet and the OC treatment. In addition, FD enhanced the pro-oxidant state in OC-treated rats characterized by (1) a fall in platelet and plasma n-3 fatty acids, (2) an increase in plasma lipid peroxidation products such as conjugated dienes, lipid peroxides, and thiobarbituric reactive substances, (3) a rise in ex vivo erythrocyte susceptibility to free radicals. Moreover, we found that OC treatment led to a reduction of plasma and erythrocyte folate concentrations associated with a moderate hyperhomocysteinemia. Under our experimental conditions, we did not find significant synergistic effects between OC and FD. We propose that, although the untoward effects associated with the OC treatment may not primarily be dependent on FD, the folic acid deficiency magnified OC-induced oxidative stress, which resulted in platelet hyperactivity by elevating the pro-oxidant homocysteine plasma concentration. Despite the limitations of this animal model, the data of the present study suggest that in addition to cigarette smoking, inadequate folic acid intake might predispose those taking OC to vascular thrombosis.

Pro-thrombotic effects of a folic acid deficient diet in rat platelets and macrophages related to elevated homocysteine and decreased n-3 polyunsaturated fatty acids

Folic acid deficiency represents a vitamin deficiency that may be due either to an inadequacy of the dietary supply or to an increased requirement. It leads to a number of abnormalities including hematological, neurological and cardiovascular disorders. In this study, we investigated whether folic acid deficiency would influence platelet and macrophage activities. For 6 weeks, rats were fed a test diet containing a low amount of folic acid (250 mu g/kg) by comparison with a control diet (750 mu g/kg). We found 40 and 32 percent reductions (P < 0.05) of plasma and erythrocyte folates, respectively in the tested group. Peritoneal macrophages of the folic acid deficient animals exhibited greater (20 x) tissue factor (TF) activity than in the controls. We also found that folate depletion significantly enhanced the thrombin- and ADP-induced platelet aggregation (+64 and + 13 percent, respectively). Moreover, the results of incubations with radiolabeled arachidonic acid indicated that platelets of folic acid deficient animals incorporated more labeling than controls did. When stimulated with thrombin, the mobilization of arachidonate from platelet phospholipids and its subsequent formation of cyclooxygenase and lipoxygenase metabolites were enhanced in the deficient animals. In particular, thromboxane biosynthesis was markedly increased. The analysis of the plasma fatty acid composition showed a decrease in the plasma unsaturation index related to a marked fall of long chain (n-3) fatty acids which was also observed in platelets. These data suggested the occurrence of an oxidative stress in folic acid deficient animals which was confirmed by increases in plasma lipid peroxidation products (more than +20 percent) and an enhanced susceptibility of erythrocytes to free radicals (+23 percent). Altogether these data suggested that folic acid deficiency altered the circulating and cellular fatty acid composition and thus influenced the balance of the platelet eicosanoid synthesis. In addition, total homocysteine and glutathione concentrations were highly increased in plasma from folate-depleted rats. From these results, we conclude that folate deficiency can potentiate the coagulation pathway mediated by the macrophage TF as well as the platelet activation process. It is suggested that these dysfunctions might be related to the loss of (n-3) polyunsaturated fatty acids. The latter could result from an increased lipid peroxidation triggered by the folic acid deficiency-induced hyperhomocysteinemia.

[Severe myopia and delivery]

AIM

There has been concern that patients with high myopia are at a risk of developing retinal tears as they go through a spontaneous delivery. Therefore the aim of the paper was to examine retinal changes in the group of female patients with high myopia before and after delivery.

MATERIAL AND METHODS

Eye examinations were performed before and after delivery in two groups of patients: 42 patients with high myopia and 4 patients with high myopia and retinal detachment surgery in one eye.

RESULTS

There was no progression of retinal changes and development of retinal tears, but in some patients retinal hemorrhages and macular edema were observed.

CONCLUSIONS

High myopia is not the indication for the cesarean section, but the patients should be examined after the delivery.

[New details of the life cycle of Myxobolus cerebralis according to the literature]

The article comprises new details of the life cycle of Myxobolus cerebralis, the parasite of the skeleton of salmonids. Although this species has been known since 1903, its complete life cycle has remained unknown till now or it has comprised mistaken details. Recently EL Matbouli et al. (1995) have described the life cycle of this parasite with numerous new data. M. cerebralis provokes in salmonids (especially in rainbow trouts) the whirling disease and heavy economical losses. Therefore the article may be useful for Polish ichthyopathologists. Besides the new description of the life cycle of M. cerebralis the authoress of the article gives her own considerations on some topics connected with this life cycle, which still remain insufficiently explained. The considerations concern the mechanism of the specificity of the invasive stages of the parasite to two species of its hosts (Tubifex tubifex and Oncorhynchus mykiss) and also to tissue specificity, the possibility of better and more effective control of whirling disease in breeding conditions through the knowledge of the complete life cycle of the parasite, the pathogenic activity of the parasite on fish central nervous system in spite of the lack of its lesions noted by EL Matbouli et al. (1995). The authoress pays attention to the necessity of future studies on the mitotic and meiotic cleavages of the developmental stages of the parasite. She considers also if the very complicated life cycle of M. cerebralis determined during the long evolution of this species may be recognized as favourable feature for it.

[Did the idea of intraocular lens implantation originate on Polish territory?]

The author described the activity of the Italian ophthalmologist Tadini who, during his work in Warsaw in 1765, planned to implant a glass ball into an eye after cataract operation. However, Tadini did not perform this operation. This fact was described in his diaries by Giacomo Casanova. The first implantation of the glass lens was performed by Casaamata in Dresden in 1795.

[Experimental studies on the influence of millimeter radiation on light transmission through the lens]

The influence of microwave radiation in millimetre range on the eye has not been investigated so far. However, it is known that microwaves of different wave-length can induce the development of the cataract. Therefore the purpose of the study was to investigate light transmission through the lens after exposure to microwave radiation in millimetre range. The studies were carried out on 22 rats exposed to microwave radiation of 5.6 mm length and power per unit area 10 mW/cm2 or 1 mW/cm2 during 58 days. Light transmission through the isolated lenses was measured spectrophotometrically. Transmission through the lenses was significantly decreased (about 33%) in the rats exposed to microwave radiation of 10 mW/cm2. The results of the study indicate that also microwave radiation in millimetre range can induce changes in the lens, predisposing to cataract development.

[Experimental studies on lesions of eye tissues in cobalt intoxication]

The aim of the paper was to examine the influence of cobalt compound on rabbit eye tissues. The lesions in the eyeball were evaluated basing on ophthalmological examination and in light and electron microscopes. The studies revealed that cobalt intoxication caused the following damages in the rabbit retina: oedema and atrophy of nerve fibres, lesions of ganglion, amacrine, bipolar, horizontal cells and nucleus of photoreceptors. Also, obliteration of choroidal vessels and changes in iris and ciliary body were found. Cataract developed in 42% of rabbits and 25% chronic purulent endophthalmitis in 25%. The results of these experimental investigations indicate that further studies on the influence of this metal on human eye tissues are necessary.

[Experimental studies on the role of lactic acid in pathogenesis of neovascularization]

In order to elucidate the controversies whether lactic acid could be the factor responsible for the initiation of neovascularization, the author examined neovascular response of the vessels of the chicken chorioallantoic membrane after implantation of filter discs soaked with different concentrations of this substance. No neovascularization of the vessels of the membrane was seen after implantation of the discs. The results of the study suggest that lactic acid is not the factor which can stimulate neovascularization.

[Amebic keratitis-keratitis acanthamoeba]

In seventeen patients who suffered of corneal ulcer, and were negative in bacteriological and mycological examinations, parasitological tests were performed between 1990-1992. Acanthamoeba keratitis was diagnosed in one patient with characteristic corneal changes of right eye following trauma. The patient was not a contact lens wearer. The amoeba found in direct smears of scraping from corneal ulcer and isolated and cloned in in vitro conditions (isolate-clone-No. 2961) belonged to Acanthamoeba polyphaga species. The trophozoites showed a low degree of invasiveness and high virulence when tested in BALB/c mice. The authors discussed the epidemiology of Acanthamoeba keratitis and pointed out to the necessity of accurate laboratory diagnosis and discerning interpretation of the results to prevent an Acanthamoeba-phobia among the potential patients and most of all among the medical staff.

[Radiometric studies of eye tissues in experimental cobalt intoxication]

Accumulation of cobalt in eye tissues were examined in rabbits which received the radioactive isotope 60Co Cl2. The studies revealed that this metal is accumulated at first in iris, choroid and ciliary body and, in smaller amounts, in cornea, sclera and retina. The least amounts of cobalt were found in lens. The contents of uveal tract was comparable with that found in heart and lungs, i.e. the organs in which lesions are the most frequent in cobalt intoxication.

[Should aminoglycosides be injected in the sub-conjunctiva after intraocular surgery?]

Basing on a case of toxic retinal lesions after subconjunctival injection of gentamycin and data from literature the author discusses suitability of this treatment after intraocular surgery. It seems that it should be used only in special cases, those with high risk of intraocular inflammation. The place of injection should be as far as possible from the surgical wound.

[Studies on the incidence of retinopathy of prematurity]

The paper presents the incidence of retinopathy of prematurity, based on the examinations of 1009 preterm infants and children with intrauterine growth retardation. The disease developed in 5.8% of all examined children but in the infants with birth weight under 1000g it was observed in 25%. In children with birth weight above 2000g, retinopathy was almost absent. Bilateral blindness was observed in 0.9% of the examined and in 11.5% children with the birth weight under 1000g. 44% blind children have appeared too late for ophthalmological examination.

[Laser gonioplasty in the treatment of primary chronic closed angle glaucoma]

The aim of the study was to evaluate of Nd:YAG laser gonioplasty performed together with iridectomy in the patients with primary chronic closed angle glaucoma. The results were compared with those achieved in patients with the same disease in whom only Nd:YAG laser iridectomy was done. In the first group normalization of the intraocular pressure was achieved in 64% and in the second only in 29% of the eyes. The best results were observed in cases with duration of the glaucoma less than 2 years and with intraocular pressure before treatment lower than 38 mmHg.

[Results of long-term observations of patients with serpiginous choroidopathy]

Long-term observations of 4 patients with serpiginous choroidopathy indicates that it is a chronic disease with characteristic recurrences. The most severe complication is subretinal neovascularization which can develop after many years since the onset of the disease and cause significant deterioration of vision. Therefore patients with serpiginous choroidopathy ought to be followed-up for a long time and informed about the possibility of complications which can appear even after a long period.

[Birdshot chorioretinopathy]

The clinical picture of birdshot chorioretinopathy has been presented, basing on the studies of 102 cases, treated in 16 university clinics and ophthalmological departments in Europe. The records of the patients were sent to the Ophthalmological Clinic of Ghent University as a contribution to an international research programme concerning birdshot chorioretinopathy. The observations reveal that this type of chorioretinopathy is a separate entity and its diagnosis should be based on the binocular occurrence of characteristic lesions in choroid, accompanied by at least two of the following symptoms: vitreous inflammation, vasculitis, macular edema and papilledema.

[Clinical examinations on pathogenesis and treatment of serous macular detachment associated with congenital optic pit]

The author reports two clinical tests performed in 6 patients for explaining the pathogenesis of serous macular detachment associated with congenital optic pit. The results of these tests indicate, that the detachment is caused by the fluid of vitreal origin. The treatment of this disease with the laser coagulation is also reported.

[Effect of cataract extraction on the results of in vivo spectrophotometry of the eye]

The authors compared the results of in vivo spectrophotometry of the eye in persons with a normal lens, in patients with aphakia and after an operation of intraocular lens implantation. The results received show that in the range of 400-500 microns half of the light registered by the spectrophotometer is connected with the lens in the eye. This speaks for the assumption that in vivo spectrophotometry in this range of the wave length may be one more method enabling an objective evaluation of the transparency of the lens. In the case of patients after operation of implantation of an intraocular lens the quantity of of the light reaching the retina is only slightly larger than in persons with a normal lens.

[Detection of early cataract changes in the crystalline lens by using in vivo spectrophotometry of the eye]

The aim of the paper was to study with the use of in vivo spectrophotometry of the eye the threshold values of the registered light above which one can observe clinically visible opacities of the lens. The performed experiments did not however show any major differences in the values of the registered light between persons with early cataract and control group because of considerable scattering of the results in both these groups. In order to explain the prognostic value of the in vivo spectrophotometry of the eye it is necessary to perform long-term observations of the further fate of persons with high values of the registered light.

Identification of 2 alpha-hydroxy-4-pregnene-3,20-dione in human pregnancy urine

2 alpha-Hydroxyprogesterone (2 alpha-hydroxy-4-pregnene-3,20-dione) was identified in human late pregnancy urine by liquid-gel chromatography, GLC and GC-MS. In addition, the following 2-hydroxylated C21 steroids were found and identified as 2 zeta-hydroxy-5 zeta-pregnane-3,20-dione, 2 zeta,20 zeta-dihydroxy-4-pregnen-3-one, 2 alpha,3 alpha-dihydroxy-5 alpha- (and 5 beta)-pregnan-20-one, two isomers of pregnane-2,3,20-triol and 2 zeta,3 zeta,16 zeta-trihydroxy-5 zeta-pregnan-20-one.

[Value of different serological tests in the diagnosis of various forms of active ocular toxoplasmosis]

The analysis of results of indirect immunofluorescence and direct agglutination reaction in patients with various forms of ocular toxoplasmosis showed that these reactions have a limited value in diagnostics of this condition. One can define a sure diagnosis of active ocular toxoplasmosis when the titre of these reactions are higher than 512. The ELISA IgM reaction is specific for the active form of this disease. The sensitivity of this reaction amounts 43-50%. In cases of iridocyclitis the results of the serological tests were similar to those of the control group; this confirms the hypothesis that the inflammation is evoked by an allergic reaction.

[Studies of the changes in crystalline lens transparency in rabbits with experimental cataract]

Changes of the transparency of lenses were checked by means of in vivo spectrophotometry of the eye ball and by light transmission through extracted lenses in the course of experimental early cataract in rabbits caused by naphthalen. The results of investigations show that changes of lens transparency evaluated by means of in vivo spectrophotometry of the eye appear earlier than the clinically seen opacity. It speaks for the advisability of undertaking of further studies on the possibility of utilizing this method for detection of precataractous conditions in humans.

Dactylogyrids on the gills of roach in central Finland: features of infection and species composition

Monogenean parasites were examined from the gills of 660 roach (Rutilus rutilus) in four interconnected lakes in Central Finland between February and November 1986 and in three of the same lakes between February and December 1988. One of the lakes is eutrophic and polluted due to a paper and pulp mill, one is oligotrophic and in a natural state, and the other two lakes are eutrophic. The prevalence of Dactylogyrus infection was always high. Differences between the lakes and the years were observed in the intensity of infection, which was significantly higher in the polluted lake. The intensity was also higher in older fish. Nine Dactylogyrus species were found, and of these D. crucifer and D. nanus were numerically dominant in all of the lakes studied, especially in the oligotrophic lake. In 1986 D. fallax, D. similis and D. suecicus constituted significant proportions of the fauna in the polluted lake. D. micracanthus was most common in the eutrophic lakes. In 1988 the species composition in the polluted lake was most similar to that in the eutrophic lake.

A traumatic cyst of the sclera

The author describes a traumatic implantation cyst of the sclera which developed about two years after an injury with a knife, which caused a perforating scleral wound. The wound was sutured with the operating microscope. The possible mechanisms of the development of this cyst are discussed. Ophthalmologists should still bear in mind the possibility of the development of cysts of the sclera after injuries, which are rare complication nowadays.

[Choroid ischemia syndrome]

Presented are the ischemic changes of the choroid on the basis of observation of patients treated in our Department in the course of the last years. In dependence on the advancement of the ischemic changes one can see 3 various types of signs at the fundus. It seems that the most proper name for these changes would be "the choroidal ischaemia syndrome". It is namely a complex of various fundus changes connected by a common pathogenesis but with various kind of causes.

[Results of experimental studies of the possibility of using low temperature in the treatment of retinopathy of prematurity]

The purpose of the paper was to study whether the use of cryotherapy can cause decrease of angiogenic activity of the primary avascular retina in kittens with oxygen induced retinopathy. The studies showed that after cryotherapy comes to a considerable decrease of angiogenic activity of this part of the retina. It indicates that cryotherapy should arrest the development of more advanced stages of retinopathy of prematurity.

[Clinical studies of the tilted disc syndrome]

Frequency of occurrence of all clinical signs in the tilted disc syndrome was studied in the paper because of variability of clinical picture in this syndrome. The most frequently occurring signs were: tilting of the disc (89%), oblique direction of the vessels (89%) and myopic astigmatism (96%). Other signs were observed less frequently: hypoplastic changes of retina and choroid in 82%, congenital conus in 45% and defects in the visual field in 55%. All sign of the syndrome were seen in 45% od the examined eyes. The most important signs of the syndrome are: tilting of the disc, oblique direction of the vessels and congenital conus.

[Treatment of disturbances in the stability of pre-ocular tear film]

Discussed are the methods of treatment of the disturbances of stability of the pre-ocular tear film and the compounds which are used. In spite of introduction of a considerable amount of new pharmaceutics in the last period the treatment of disturbances of this kind needs a large amount of patience as well from the side of the patient as from the ophthalmic specialist.

[Diagnosis of disturbances in pre-ocular tear film]

Presented are the actual possibilities of diagnosis of the disturbances of stability of the tear fluid. In spite of the existence of quite numerous clinical and laboratory diagnostic tests it is necessary to elaborate new, simple and safe methods of examination which may be applied in the clinical practice.

[Physiology and function of pre-ocular tear film]

Discussed are in detail the genesis and physiology of the lacrimal film and the role played by its separate layers in securing a normal functioning of the cornea, conjunctiva and the lids. Described are also the defensive mechanisms of the eye in which the lacrimal film takes also part and the role of the lids in the process of its regeneration.