Welding-arc maculopathy may develop following prolonged exposure to welding arc radiation without adequate protection of eyes. It generally affects young people because of their occupational lack of knowledge and also due to presence of relatively clear ocular media. Most common injury with welding arc radiation is photophthalmia due to ultraviolet (UV) light absorption. Welding-arc maculopathy may be underreported because of its transient clinical features, which may be masked by associated photokeratitis.
The effect of light on retina is being recognised since the time of Plato, who gave description of eclipse blindness.
Photic (related to light) retinopathy is a generalised term used for retinal damage produced by light. This may be due to solar viewing or may be produced even by use of operating microscope.
Increase in retinal temperature is below photocoagulation thresholds. The injury is due to photochemical effects from UV and short blue wavelength exposure. Similar photochemical macular burns may take place after brief exposure to the flash associated with short-circuiting of a high-tension electric current. Use of drug phenothiazine may increase the susceptibility to damage due to the welding-arc radiation.
In metal-arc inert gas welding, the arc is ensheathed with inert gas to prevent oxidation of molten metal. The gas changes emitted radiation into visible and infra-red range, which may produce thermal and photochemical damage to the retina. This is unlike electric arc where the radiation is predominantly in UV range.
The appearance of retinal lesions and clinical course of welding arc exposure are similar to those of solar retinopathy. However, welding-arc maculopathy requires more prolonged exposure as compared to solar retinopathy.
References
Yanoff Myron, Duker Jay S. Ophthalmology Fourth Edition. Elsevier Saunders 2014. P 461- 466.
Symptoms include
Mechanism
There is evidence which suggests that the retinal damage due to welding-arc exposure is probably photochemical rather than thermal, and is primarily caused by the wavelengths at the blue end of the light spectrum.
Similar macular burns may occur following brief exposure to the flash associated with short-circuiting of high-tension electric current.
Prolonged welding-arc exposure over a period of minutes or longer may cause
Diagnosis depends upon the clinical history, clinical features, and investigative procedures.
Besides clinical history of exposure with characteristic symptoms, patient presents with clinical signs as
A yellow oedematous lesion with greyish borders may develop acutely in the foveal region. There may be multiple spots. Slight exposure may reveal an altered foveal light reflex. With time, this is replaced by irregularity in retinal pigment epithelium (RPE). In more severe cases, the yellow spot may change to a reddish spot. This may lead to foveal depression or a permanent lamellar defect.
Fluorescein angiography may be normal, but more severe damage may cause foveal RPE defects.
Optical coherence tomography (OCT) characteristically shows well-defined outer retinal hypo-reflective space which primarily involves photoreceptor inner and outer segment layers.
Amsler grid testing may delineate small central or paracentral scotoma.
Differential diagnosis
There is no effective therapy for welding-arc maculopathy.
Vision usually improves with passage of time. Some patients may be left with permanent defects and loss of vision.
Education of people may reduce visual morbidity.
