Those pathological processes in the body that occur under the influence of certain factors of the external working environment are considered occupational diseases.
Occupational hazards have a multilateral effect, affecting the entire body with various pathological changes in individual organs and systems, including in the organ of sight.
Eye damage by physical factors
Ultraviolet rays have a photochemical effect. Nucleoproteins have the highest sensitivity in cells.
Ultraviolet exposure to the eye causes electrophthalmia, which develops acutely after 6-8 hours after exposure to the rays. With a very intensive dose, the latent period is reduced to 1-2 hours, and with a small dose, to 12-14 hours.
There is a sharp pain, photophobia, tearing, blepharospasm.
On examination, conjunctival hyperemia, sometimes chemosis, pinpoint epithelial defects of the cornea in the form of small erosion, conjunctival and pericorneal injection of the eyeball, pupil constriction are determined.
All phenomena usually pass in 1-2 days.
Electrophthalmia occurs when performing such work as electric arc welding, autogenous welding and cutting, when using mercury-quartz lamps.
Similar phenomena are observed in persons working in snowy areas without eye protection with light filters, in bright sunlight (snow blindness).
Frequent exposure to ultraviolet rays can lead to the development of chronic photophthalmia: increased sensitivity to light, chronic conjunctivitis, blepharoconunitis. Very rarely, with a significant lesion of the cornea, the lens can be simultaneously affected (a cataract develops).
Cold lotions with water, instillation of local anesthetics – 0.5% solution of dikain, 1% solution of lidocaine, 2% solution of novocaine, and also antibacterial drops – 0.25% solution of levomycetin, tetracycline, erythromycin ointment.
Eye damage by ionizing radiation
Ionizing radiation includes the emission of light quanta or elementary particles, which can cause ionization or excitation of atoms or molecules.
During ionization, electrons are pulled out from the atomic shells, and negative and positive ions are formed.
Ionizing effect is given by electromagnetic oscillations with high energy of quanta, including X-rays and gammaluchi, as well as radiation of charged particles – electrons, positrons, proton nuclei, helium nuclei (alpha particles) and other chemical elements.
Neutrons deprived of charge in collisions with atomic nuclei can also cause ionization. Professional damage by ionizing radiation takes place in nuclear power at all stages: in the extraction of uranium ore, in the extraction and enrichment of uranium, in the work with fuel cells, in the storage and processing of waste. Radiation damage can occur when working with radionuclides in industry, agriculture, and medicine.
Each person, especially living in a large city, is exposed to natural and domestic background radiation.
Both external and internal exposures are possible (due to the ingestion of radioactive substances through the gastrointestinal tract, lungs, and skin).
In the human body as a result, a number of complex functional and organic changes occur, such as the destruction of protein structures, disruption of the activity of various enzymatic systems, redox processes, and more.
The eyeball is completely permeable to almost all types of ionizing radiation.
Scientists noted that alpha particles cause superficial keratitis, beta particles, borderline X-rays – eyelid dermatitis, keratoconjunctivitis, and often cataracts. Neutrons, positrons, gamma rays, hard X-rays – keratoconjunctivitis, cataracts, uveitis, retinopathy, secondary glaucoma, atrophy of the eyeball and orbital tissue.
When ionizing radiation in large doses, atrophy of the eyelid skin develops, it becomes thinner, depigmented, its edge smoothes, hair follicles are affected, and as a result of this – loss of eyelashes. Cicatricial shortening of the arches of the conjunctiva leads to twisting of the eyelids, the defeat of the tubules, their deformation and obliteration.
Radiation keratoconjunctivitis at the clinic resemble electrophthalmia. In severe cases, erosion, corneal ulcers and even iridocyclitis can occur. The lens is the most radiosensitive structure in the eye.
A cataract can develop after massive single exposure and repeated action of small doses.
At the initial stage, ray cataract has a characteristic appearance: at the posterior pole of the lens, under the capsule there are clusters of fine-point opacities, which gradually take the form of a disk with clearly defined edges with a diameter of -4 mm.
Vacuoles are formed in the posterior cortical layer. Subsequently, vacuoles and opacities appear in the front layers of the lens, and then the entire lens gradually becomes cloudy.
In the initial stage, visual acuity is not significantly reduced, and as cloudiness increases, it progressively decreases.
Damage to the retina by ionizing radiation is rarely observed. Vascular dilation, retinal edema, hemorrhage, and vat-like exudative foci are characteristic of radiation retinopathy. Perhaps the development of retinal detachment.
In rare cases, secondary glaucoma develops, which can occur with direct damage to the drainage system of the eye and as a consequence of radiation damage to the retinal vessels.
In the latter case, neovascular glaucoma develops, which is difficult even to surgical treatment.
Infrared rays have a thermal effect.
According to biological activity, they are divided into short-wave (760-1400 nm) and long-wave (from 1500 nm and above).
The heat exposure of these rays is determined by their absorption by the skin: the shorter the wavelength, the more radiation penetrates the skin and does not cause a sensation of heat and burning
The long-wave infrared radiation is absorbed by the surface layers of the skin, where there are many thermoreceptors, therefore a burning sensation is noticeable.
Under production conditions, workers who have contact with powerful fluxes of infrared radiation experience various disorders of the organ of vision.
Infrared radiation has a pronounced thermal effect on the eyelids, the conjunctiva, it has the ability to penetrate deep into the eyeball and have a damaging effect on the lens.
The maximum temperature increase is noted in the posterior chamber of the eye, which is associated with the absorption of radiation by the pigment epithelium of the iris, and the enzymatic zone near the lens equator is damaged.
The mechanism of development of lens opacities is associated with the effect of infrared radiation.
Prolonged work with sources of intense infrared radiation (molten metal, glass, technical furnaces, etc.) causes chronic blepharitis and blepharoconjunctivitis.
Professional thermal cataract (cataract glassblowers, metallurgists) in the initial stage has characteristic clinical features. Opacification occurs first at the posterior pole of the lens, under the capsule. It has the appearance of a fine-grained, but clearly defined turbidity. In the subsequent turbidity progresses, and the lens becomes cloudy.
Characteristic of thermal cataracts is the detachment of the zonular lens plate in the pupillary zone. It has the appearance of a transparent film located on the front surface of the lens.
Only a small part of the near infrared rays penetrates into the posterior part of the eye, absorbed by the retinal pigment epithelium.
When looking at a strong light source (sun, arc welding), the retina and choroid are affected. Patients develop photophobia, chromatopsia, and a feeling of a floating cloud in the center of the visual field. Then a relative or absolute central scotoma arises, visual acuity decreases.
Ophthalmologic changes may be absent even with severe central scotoma. Often you can see swelling of the central region of the retina with point hemorrhages.
In the future, there are yellowish-white lesions in the macular area, which can significantly reduce vision.
Sometimes, however, there is a reverse development of the process with full restoration of vision.
Radiant energy, or light, is the energy of electro-magnetic radiation that occurs in an alternating electromagnetic field.
The sector of electromagnetic radiation is divided into long-wave, medium-wave and short-wave parts.
Longwave is radio waves. The middle part includes infrared radiation (wavelength from 500,000 to 760 nm), visible light (760-400 nm) and ultraviolet rays (390-5 nm).
The short-wave part includes X-rays (wavelength 40-0.01 nm) and gamma rays (0.05-0.001 nm).