Radiation sources and equipment specifics
Medical practice actively utilizes laser technologies due to the unique physical properties of the beam—its sharp directivity and monochromaticity. Depending on the task at hand, systems generate radiation with various characteristics. Low-intensity physiotherapeutic devices, classified as light therapy equipment, operate at wavelengths of 0.63, 0.85, 0.95, and 1.3 µm. The power of such equipment varies from 0.1 to 2–4 W, and the frequency ranges from 0.1 to 3 kHz.
Equipment can operate in continuous or pulsed generation modes. Pulsed laser light has a more pronounced therapeutic and prophylactic potential. Its main advantages lie in the ability to penetrate deeper into biological tissues, as well as the possibility of differentially selecting optimal and peak radiation parameters for specific diseases. The laser scalpel has firmly established its place in surgical practice, oncology, and ophthalmology, whereas laser biostimulation methods are widely demanded in dermatology, dentistry, and physiotherapy.
Therapeutic effects of laser exposure
The impact of generated light on living tissues triggers a cascade of biological reactions that collectively form a powerful clinical response. This spectrum of action allows laser physiotherapy to be classified as pathogenetic multifactorial therapy, which often surpasses traditional complex treatment in its efficacy.
The main therapeutic and prophylactic effects include:
- Powerful anti-inflammatory and anti-edematous action.
- Normalization of microcirculation in the blood and lymphatic vessels.
- Pronounced fibrinolytic and thrombolytic activity.
- Activation of cellular metabolism, improved oxygenation, and stimulation of tissue regeneration.
- Neurotropic, analgesic, and muscle-relaxing action, as well as desensitization.
- Bacteriostatic and bactericidal influence.
- Immunostimulation and a sustained general strengthening effect.
Complex of occupational hazards
Despite the undeniable therapeutic benefit for patients, the operation of laser equipment is associated with risks for medical personnel. Equipment malfunctions or improper operation lead to the combined impact of occupational hazards.
In the workspace, a specialist may be exposed to:
- Direct laser radiation (direct, scattered, or reflected).
- Concomitant ultraviolet and light radiation.
- Industrial noise.
- Toxic gases, aerosols, dust, and tissue pyrolysis products (generated during laser scalpel operation).
Additional physiological load on the body is created by ergonomic factors: constant strain on the visual analyzer and local loads on the muscles of the hands and forearms.
Eye injury: from UV to IR spectrum
The organ of vision is the primary target when working with quantum generators. The nature of the pathological process directly depends on the wavelength (spectrum) of the radiation.
1. Ultraviolet (UV) and far infrared (IR) spectral range Radiation of these ranges is completely absorbed by the superficial structures of the eye—the conjunctiva, cornea, and lens.
- Exposure to UV lasers provokes very painful conjunctivitis and corneal burns. The clinical picture is completely identical to injuries caused by electric arc welding.
- Gas CO2 lasers (wavelength $\lambda$ = 10.6 µm) cause protein denaturation, leading to the formation of transient opacity foci in the cornea.
2. Visible and near IR spectral range Exposure to a direct or specularly reflected beam of sufficient power damages deep structures. Burns and hemorrhages in the retina are formed, leading to the development of a chorioretinal scar and decreased visual acuity. A characteristic manifestation is the sudden loss of a part of the visual field (development of a scotoma). An important distinction: this process proceeds without pain.
Chronic exposure and skin effects
Prolonged work with lasers leads to chronic changes in visual functions. By the end of the work shift, personnel complain of visual fatigue, dull or sharp pain in the eyeballs, pronounced photophobia (intolerance to bright light), lacrimation, or, conversely, a sensation of dryness. Objectively, visual acuity generally remains preserved. However, there is a dangerous increase in color discrimination thresholds, an increase in dark adaptation time, and in some cases, narrowing of visual fields.
Effect on the skin A direct or diffusely reflected beam can cause skin reactions of varying severity—from mild erythema to a burn. Even mild forms of exposure do not pass without a trace: they manifest as functional shifts, such as changes in the activity of intradermal enzymes and disruption of skin electrical conductivity.
In addition to local lesions, individuals working with lasers may experience systemic general changes. Most often, they are expressed as non-specific functional disorders of the nervous and cardiovascular systems.
Briefly: answers to topical questions
What systemic changes in the body does chronic exposure to laser radiation cause?
Chronic exposure to laser radiation is associated with non-specific functional disorders of the nervous and cardiovascular systems. Medical examinations of individuals working with lasers reveal asthenic syndrome, asthenovegetative syndrome, and vegetative-vascular dysfunctions. Prolonged work with lasers can cause visual fatigue, dull or sharp pain in the eyeballs, intolerance to bright light, lacrimation, or a sensation of dryness.
What personal protective equipment (PPE) is used when working with medical lasers?
When working with medical laser devices, specialized protective goggles with light filters are used for the mandatory protection of the retina. Goggles with specialized dark light filters are used, which are classified according to the degree of fit to the face:
- Fitted goggles — contact the face by part or the entire contour of the frame (available in open and closed types).
- Non-fitted goggles — do not contact the face along the contour (protective lorgnettes, visor-mounted goggles, clip-on goggles).
Closed fitted goggles are additionally subdivided by ventilation type into models with direct and indirect ventilation of the sub-goggle space.
To remember the depth of eye damage: UV and Far IR strike the Surface (cornea, pain), while Visible and Near IR penetrate Deep (retina, scotoma without pain).
Class and exam questions
How does an ultraviolet laser affect the eyes?
UV radiation is absorbed by superficial structures (conjunctiva and cornea), causing extremely painful burns clinically identical to eye injuries from electric arc welding.
Is retinal damage by a visible laser accompanied by pain?
No, the formation of retinal burns and the development of a scotoma under the influence of the visible and near IR spectrum proceed without pain.
What vision changes develop with chronic irradiation?
Visual acuity is usually preserved, but color discrimination worsens, dark adaptation time is prolonged, and photophobia and dry eyes appear.
What else to study on this topic
- Mechanisms of laser biostimulation in living tissues
- Physics of corneal protein denaturation under CO2 laser exposure
- Specifics of changes in intradermal enzyme activity during mild irradiation
- Toxicological characteristics of biological tissue pyrolysis products
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