bubble_chart Overview

The wavelength ranges from 760nm to 4,000,000nm, occurring in taiyang or hot objects. The long-wave portion causes no harm to tissues. It can be focused using lenses or mirrors and dispersed using prisms. The biological effect of infrared rays is primarily thermal. Infrared rays are easily absorbed by dark-colored objects. High-intensity infrared rays can cause tissue necrosis and protein coagulation. Far-infrared rays can only penetrate tissues up to 0.5cm and are almost entirely absorbed by the corneal membrane and aqueous humor. Near-infrared rays can penetrate tissues up to 3~cm, reaching the retinal membrane, where they are absorbed by pigments in both the iris and retinal membranes.

bubble_chart Etiology

1. White internal visual obstruction caused by short-wave infrared rays

Infrared rays easily penetrate transparent media and reach the interior of the eye. The refractive media lack blood vessels and have poor heat dissipation properties. Additionally, the adjacent uvea can absorb large amounts of radiation, making it susceptible to damage and resulting in white internal visual obstruction. If infrared rays are concentrated on the macula, it can lead to macular injury.

2. Solar retinopathy and choroidal burns

Mainly caused by the thermal energy generated when short infrared rays and visible light are refracted and concentrated by the refractive media, leading to burns in the retina and choroid. This is commonly seen in cases of naked-eye observation of solar eclipses. It occurs more frequently in young individuals and those with emmetropic eyes, while being rare in individuals with high myopia. It is also related to the nature of the eclipse, season, time, and weather conditions.

bubble_chart Clinical Manifestations

1. White internal visual obstruction caused by short-wave infrared rays

The typical changes of infrared white internal visual obstruction usually start from the posterior pole. Initially, there is a small ink-stain-like wheel-shaped or disc-shaped opacity in the posterior cortex of the lens, which may also appear as a spider-web-like opacity with a shiny crystalline center. The opacity is relatively thin and has clear boundaries. Another characteristic is that the superficial layer of the anterior capsule may peel off, curl up, and float freely in the anterior chamber. This differs from capsular glaucoma, where the peeled anterior capsule often appears as powdery debris, starting beneath the iris and gradually covering the anterior layer of the iris, blocking the anterior chamber angle and leading to increased intraocular pressure.

2. Solar retinal and choroidal burns

The initial subjective symptoms include a dazzling sensation, followed by photophobia, photopsia, and abnormal color vision (red, yellow, blue). After 24 hours, floating dark shadows become dense scotomas, which may be temporary or permanent central scotomas. Visual acuity drops to 0.5–0.1 or lower, accompanied by metamorphopsia. Fundus examination reveals that the lesions are confined to the macular area. In mild cases, the macula appears darker in color; in severe cases, there is edematous elevation, appearing gray with small hemorrhages. In typical cases, there is a small yellow-white spot at the fovea, surrounded by pigment spots. In severe cases, perforation or retinal detachment may occur.

bubble_chart Treatment Measures

1. White internal visual obstruction caused by short-wave infrared rays

For early-stage workers with infrared-induced white internal visual obstruction, they should be removed from the infrared radiation environment. If there is visual impairment and the lesion is only in the posterior pole of the lens, an iridectomy can be performed. If the lens has become completely opaque while the retinal function remains normal, a white internal visual obstruction extraction can be performed.

2. Solar retinopathy and choroidal burn

After injury, corticosteroids, vitamin B, and vasodilators can be administered. Mydriatic eye drops and retrobulbar injections of hormones may also be used.

bubble_chart Prevention

Strengthen industrial hygiene education and choose appropriate protective eyewear. Lenses containing ferrous oxide and GRB colorless lenses have an absorption rate of over 90% for infrared spectra. Do not look directly at the taiyang; when observing a solar eclipse, wear qualified protective glasses, such as newly produced CR-39 optical resin lenses.