Ophthalmology in Bulgaria.

Bulgaria faces a marked shortage of ophthalmic resources. There are over 600 ophthalmologists for this Balkan nation of 8.9 million, giving Bulgaria a ratio of ophthalmologists to overall population that is similar to that of the United States; however, less than 20% of these ophthalmologists perform surgery. No formal residency or fellowship training programs exist in the country. Ophthalmic textbooks and journals are written predominantly in Russian and are in short supply. Pharmaceutical supplies are extremely limited. The leading cause of blindness in Bulgaria is cataracts that have not been treated surgically. Most cataracts are removed with intracapsular extraction. However, in the major cities, extracapsular cataract extraction with implantation of intraocular lenses is available.

On the epidemiology of cataract in Bulgaria.

Cataract prevalence in Bulgaria is a subject of current registration and of research studies. Our report deals with three basic sources: national statistics data, epidemiological study on cataract incidence, and clinical observation on risk factors. In 1985, 7.9 cataract cases per 1,000 population (over 15 years) have been registered. Cataract extractions increased from 6,972 (1980) to 8,050 (1984). Cataract prevalence study on 2.5 representative samples during the 1970 census in Bulgaria demonstrated 3.6% for urban and 2.5% for rural populations for 1 year of observation. The data showed a 10-fold increase when additional ophthalmologic examination of a given sample had been performed. The clinically based study of cataract characteristics and risk factors includes about 600 patients for a 1-year period. In this report the data according to sex and age distribution, type of cataract and the presence of systemic disease have been presented.

Blindness and visual impairment in western Bulgaria.

The Sofia Eye Survey was a population-based blindness and visual impairment survey of 6,275 randomly selected men and women from the Sofia district and Sofia city in western Bulgaria. A complete house-to-house census on all adults over age 40 years was performed, and visual acuity performed on 98%. We referred 171 subjects for a complete dilated ophthalmologic examination because the pinhole vision in the better eye was 6/18 or worse. Trained ophthalmologists refracted all referred subjects and then examined them with a slit lamp and ophthalmoscopy to determine the cause of visual loss. The rate of blindness (defined as vision in the better eye worse than 3/60) in this population was 0.49% and the rate of visual impairment (6/18 to 3/60 in the better eye) was 0.83%. The leading cause of both blindness and visual impairment was cataract. These data from the first community-based survey of blindness in Eastern Europe suggest that the rates of blindness and visual impairment are similar to those reported from other developed countries.

Effects of Serotonin and Histamine on the contractile activity of smooth-muscle strips of sheep complex stomach.

The effect of histamine and serotonin is studied on strips of the two smooth-muscle layers from the different sections of the complex stomach. Histamine in concentration of 10(-9) to 10(-4) g/ml has no visible effect on preparations from the rumen and reticulum. In strips from the omasum as well as from the proximal and antral regions of the abomasum inhibitory effect is observed mainly with respect to the spontaneous phasic activity of the strips. Serotonin in concentrations of 10(-8) to 10(-4) g/ml has an excitatory effect in almost all preparations studied. Of the forestomach strips it is mostpronouced in rumen strips. The effect consists in an increase of the tone of the preparations. In the proximal region of the abomasum is effect also consists in a rise of the tone, while in strips from the antral region it causes a rise in the amplitude and frequency of the phasic contractions. Serotonin in the concentrations tested has an inhibitory effect only on omasum preparations.

Provoked iris ischaemia in the rabbit. II. Histochemical localization of sodium fluorescein.

The distribution of injected sodium fluorescein in the iris and ciliary body of albino rabbits was studied in normal animals and in animals subjected to different surgical procedures. The study was performed with two techniques: whole-mount preparations and the paraffin-section method on freeze-dried eyes. Fluorescein distribution showed marked changes after surgical procedures as a result of reduced blood perfusion. In normal iris vessels no penetration of fluorescein was observed. The permeability barrier was impaired if there were ischaemic conditions in the anterior segment. The results were compared with clinical and iris angiographic studies.

Provoked iris ischaemia in the rabbit. I. Clinical and histopathological examinations.

Various surgical procedures were performed on albino rabbits, which impaired anterior segment blood circulation. Our early and late clinical observations showed a consequent development of anterior-segment ischaemia into anterior-segment necrosis. The significance of different surgical procedures for resulting complications is discussed. Histopathological observations showed ischaemic changes in the anterior segment: iris and ciliary body atrophy, cataract formation, rubeosis iridis. Even though changes in the anterior segment were not observed on biomicroscopic examination in the cases with ligation of one LPCA, histological studies revealed different degrees of sectoral iris atrophy with minor rubeosis.

Neurotransmitted responses of smooth-muscle strips of complex sheep stomach after electrical field stimulation.

Contractile responses to stimulation of nerve elements in smooth-muscle strips of complex sheep stomach suggest the existence of inhibitory and excitatory nerve structures in preparations from all compartments. Pharmacological analysis of the responses shows that they are mediated by cholinergic excitatory, noncholinergic excitatory and nonadrenergic inhibitory nerve elements. Comparison of the distribution of the cholinergic nerve structures shows that there are no essential differences between the different compartments. Differences are observed between strips cut in the direction of the two muscle layers, the effect of the cholinergic nerve elements being more pronounced in the longitudinal strips compared with the transverse ones. Noncholinergic excitatory effects of nerve stimulation are observed in all compartments of the complex stomach. Nonadrenergic nerve structures with inhibitory effect on the muscle strips are found in all compartments of the stomach. It is assumed that in the rumen they have spontaneous activity which inhibits the capacity of the smooth muscles in this part of the stomach for spontaneous phasic contractions.

Character of the mechanical activity of the various sections of the complex stomach upon vagal stimulation.

The experiments are carried out on chloralose-anaesthesized sheep (50-70 mg/kg). The increase in the force, frequency and duration of the stimulating impulses in a geometric progression leads to an increase in the amplitude of the contractions in all sections of the complex stomach. The amplitude and nature of the evoked contractions for one and the same parameters of stimulation are different in the different sections. The latency of the response in the reticulum is always shorter and its contractions increase faster than in the other sections. The relaxation of the muscles after elimination of the stimulation to the initial level is slowest in the rumen and in the case of high parameters of stimulation it takes more than 10 min.