According to the absolute majority of experts on a labour safety, acoustic vibrations are the most sanitary dangerous factors of industrial environment. There is some information about some ocular characteristics as a result of mechanic acoustic vibration influence. However, it should be noted that preventives and correction methods of unfavourable effects of acoustic vibrations on the visual analyzer haven´t been worked out yet, owing to pathogenetic mechanisms of acoustic ophthalmopathy development.
Our investigation object is to study mechanisms of acoustic ophthalmopathy development.
Materials and methods. 217 machine-building plant workers were examined. Conditions of work in the workshops: influence of infrasound, whose intensity level exceeds maximum allowable sanitary norms on 16-20 db and runs up to 96-100 db on the frequency of 8-16 Hz. The total equivalent level of noise intensity in one shift exceeds the maximum allowable level on 11-13 dbA in average.
Biomicroscopy was carried out by means of the stereobinocular microscope "Zeiss". The state of eye bottom vessels was studied using the ophthalmoscope 11750-VBI, Welch Allyn; the electroretinogram registration was conducted with A. M. Shamshinova´s methodology (1998).
The results of research. The clinical observations showed that protracted influence of acoustic vibrations with pressure even within the normal range upon the human organism stimulates functional changes in the visual analyzer which lead, first of all, to visual discomfort.
Primary signs of microcirculation disorders (like aterosclerotic and hypertonic changes) were revealed by means of biomicroscopy of conjunctiva (especially at persons of 40 years and older). One part of examined (23.76%) had microaneurisms of conjunctiva vessels, more often in the area of the lower sector of limbus and in the area of the lower transitional pleat of mucous eye membrane.
The ophthalmoscopy of vessels of an eye bottom helped to bring to light arterial wall induration in the pool of the second order arterioles, venous plethora, venous glomes like Gwist´s symptom, there was also revealed Salus-Gunn´s symptom of the I-II degree. The frequency of exposure of vascular changes (like hypertonic, aterosclerotic and aterosclerotic-hypertonic angiopathy) in the examined group exceeds on 71.5% analogical displays of vascular pathology diagnosed in the control group.
Little decline of amplitude parameters of macular electroretinogram was observed at examined persons, both red and green stimuli. Statistic analysis allowed revealing a reliable distinction (p<0.001) between the groups of the amplitude of the wave A of macular electroretinogram of the green stimulus, which mainly rod cells and cones of macular area responds to.
Taking into consideration that there were no revealed significant distinction of parameters in macular electroretinogram on the red stimulus, which mainly macular area cones react to, it was possible to suppose that electrogenesis abnormality as a reliable decline of the amplitude of the wave A of macular electroretinogram on the green stimulus is conditioned, to a considerable extent, by dysfunction of rod cells, situated in the stimulated area.
Bioelectric retinal activity was also investigated at stimulation of low frequency. A reliable decline of electroretinogram amplitude for 10 Hz was revealed at examined persons in comparison with the control. Reliable extension of time interval N-P was considered to be a sign of disruption of interneuronal correlation in external layers of retina, most probably at the stage of information transmission from photoreceptors to neurons of the second level.
Thus, clinical observation of machine-building plant workers achieved that protracted influence of acoustic vibrations with pressure even within allowable level upon the human organism provokes functional changes in visual analyzer, which lead to, at the first place to visual discomfort. Ophthalmoscopy revealed vascular changes like hypertonic, aterosclerotic and aterosclerotic-hypertonic angiopathy in the group of examined persons. This angiopathy exceeds on 71.5% analogical manifestations of vascular pathology diagnosed in the control group. Bioelectric retinal activity was also analyzed. Decline of the electroretinogram amplitude for 10 Hz was displayed at persons from examined group in comparison with the control. Given investigation allowed suggesting a working classification of acoustic ophthalmopathies, which permits to work out a complex of sanitary and pharmacological measures for the prophylaxis and treatment of manifestation of acoustic vibration influence upon the eye.
The article is admitted to the International Scientific Conference «Present-day problems of experimental and clinical medicine», Thailand (Bangkok, Pattaya), December 19-27, 2007, came to the editorial office on 19.11.07