Ocular Health Defects Among Welders In Owerri Metropolis, Imo State

ABSTRACT

Welding is the most effective means of joining metals, welding exposes welders to a variety of work-related hazards, which may be deleterious to their health. This study of ocular health defects among welders in Owerri metropolis of Imo State was of a cross sectional design using 200 subjects. The ages of the subjects ranged between 18 and 55 years selected at random. Examined with pen light, visuals acuity chart and ophthalmoscope in their respective work shop. Aimed to ascertain possible ocular defects among welders and to verify if there is compliance in use of protective eye wears by the welders. The study revealed ocular defects  with reduced vision or poor acuity with the percentage frequency of 37.3%.pinguecula(30.3%) and then followed by pterigium(24.4%), Corneal opacity and limbal changes are the least with percentage frequencies of 7.0% and 1.2% respectively. which is an indication that Welders are prone to ocular defects. As shown in the frequency distribution table represented on pie charts and bar charts, 2% constantly wore eye wear, 14% (often users) 41% (occasional users), 43% (Never Users). About 1.3% of the defects occurred among regular users 43.8% (occasional users) 45.8% (Never Users). From the analysis mentioned, it was discovered that ocular related defects are prominent among non users of protective eye wears. It was therefore, recommended that proper orientation and strict compliance on the use of protective eye wears among welders be advocated.

CHAPTER ONE

1.0    INTRODUCTION

1.1 Background of the study

Ocular health defects may develop slowly (progressively), or suddenly and may be temporary or permanent, depending on the cause. Vision loss may affect one or both eyes. It can as well cause blindness or may affect only peripheral or only central vision.

Healthy vision is a treasured sense and once it fails, nature is not appreciated. This is why proper attention and care should be taken by both individuals and health care professionals in maintaining the integrity of the eye bearing in mind that once the eye  (vision) is lost it cannot be replaced, even if it can, it is still beyond the reach of majority of the masses.

Ocular injuries occur in industries of which welding industry is one of them. The welding industry is an establishment engaged in the business of production of goods and services with metallic, electrical and gas materials.

Industrialization is desired development since it ensures higher standards of living for the citizenry. In industries, there is bound to be risk or dangers which exist in various types and natures. The risks may be exposure to harmful chemicals, trauma, and exposure to radiation as well as foreign body infiltration. These are generally referred to as hazards and ocular hazards when the ocular structure is/are involved.

Welders are exposed to occupational hazards like other industries. Traumatic eye injury is one of the most important occupational health and safety issue for the workers engaged in welding process (Zulfiqar, Amir, Amjad, 2010).

Welding process exposes workers to mechanical, radiant, thermal or chemical energy. Injuries most often occur during a normal mechanical operation of welding machine and not as a result of any mechanical malfunction (Zulfiqar, Amir, Amjad, 2010). Frequent work activity at the time of injury in welding industry include; welding, grinding, cleaning, brushing or observing a welder.

Welding is the most effective means of permanently joining metals. Though there are about 60 different methods of welding, gas and arc welding are the ones commonly practiced in the developing countries (Ajayi et al., 2011).

The ultraviolet and infrared radiations of electric arc welding can cause painful burn or even more serious eye damage, chemicals, liquids and caustics causes damage due to splash or spring (Ajayi et al., 2011).

The ocular media have been found to absorb some of the light wavelength produced by these welding processes. The corneal epithelium and conjunctiva absorbs ultraviolet wavelength of between 200nm and 315nm (UV-B and UV-C) the lens nucleus and epithelium absorbs the wavelength between 295nm and 400nm (UV-A and part of UV-B). it is known that with age, the filtering effect of the crystalline lens increases in concentration of chromosphores which absorbs the radiation. Most of the ultraviolet is therefore absorbed by the cornea and lens resulting in photochemical damage (Emegwamuo, 2011). All welding processes produce radiation in the ultraviolet, visible and infrared spectra.

Welders have been identified as a high risk group for occupation related eye injuries and eye disorders due to their exposure to ultraviolet radiation (Zulfiqar, Amir, Amjad, 2010).

The medical and safety problems associated with welding include skin burns, fume inhalation, electric shock, overheating, injuries resulting from explosion of fire, active keratitis (welder’s flash), ocular foreign bodies and death (Ajayi et al., 2011).

Work related eye injuries constitute a public health problem being responsible for significant morbidity. Many eye injuries may be of a minor nature. Serious injuries may occur and even injuries of a minor nature can have significant consequences without appropriate care.

Eye injuries account for a substantial proportion of all work-related injuries. They are considered to be largely preventable, especially if adequate machine guards are positioned over obvious hazards (Ajayi et al., 2011).

Welders also engage in high risk activities like cutting, fitting, chiseling and hammering, further increasing the risk of occupation eye injuries resulting from flying particles, fragments and sparks.

1.1.1 Welding and types

Welding is a process of joining two similar or dissimilar metals by fusion with or without the application of pressure and with or without the use of filter metals (Jonathan et al., 2013).

Welding is broadly classified into two groups;

1. Forge or pressure welding
2. Fusion or non-pressure welding

Forge or pressure welding is further divided into the following;

1. Blacksmiths fire – blacksmith forge welding
2. Cold pressure welding
3. Friction welding

Electric current resistant welding. Further classified into:

1. Spot welding
2. Seam welding
3. Projection welding
4. Upset butt welding
5. Flash butt welding
6. Percussion welding

Fusion or non-pressure welding with additional filler mint is divided into;

1. Gas oxy-acetylene welding
2. Electric arc atomic hydrogen welding – further divided into;
3. Carbon arc welding
4. Metal arc welding
5. Submerged arc welding
6. Stud arc welding
7. Inert gas welding – further divided into;
8. Tungsten inert gas welding and
9. Metallic inert gas welding (Jonathan et, 2013).

Electric current resistant welding

Has the primary function of converting electrical energy to heat energy, at a temperature of about 10,000F (5,500^oC) by forming a mixture of ionized (charged) particles. This type of pressure welding is used for joining pieces of sheet metals or wires (Jonathan et al., 2013).

Arc welding

This is a fusion welding process in which the welding heat is obtained from an electric struck between the work (or base metal) and an electrode. The temperature of heat produced by the electric arc is of the order of 6000^oC to 7000^oC (Jonathan et al., 2013).

Both direct current (D.C) and alternating current (A.C) may be used for arc welding but the direct current is preferred for most purposes.

Gas welding

Most common type of fusion welding in which the heat is obtained by the combustion of a fuel gas. The most widely used gas combination for a hot flame for welding metals is oxygen and acetylene (C₂H₂) in which flame temperature are produced by oxy-acetyl and oxygen is 3200^oC.

Welding torch

It is also known as blow pipe. It is a tool for mixing the oxygen and acetylene in the desired volumes and burning the mixture at the end of a tip which produces a high temperature flame.

The welding torch is commercially available in the following two types;

1. Injector or low pressure type and
2. Positive or equal pressure (also known as high pressure) type .

1.1.2 Welding defects associated with the eye structure

Physical or chemical defects can be a serious threat to vision if not appropriately taken care of. Eye injuries account for one quarter of all welding injuries, making them by far the most common injury for welders (Zulfiqar, Amir, Amjad, 2010).

Most welding related ocular defects are reversible, with more than half of injured workers returning to work in less than two days and 95% in less than seven days. Some eye defects are irreversible and permanent visual impairment occurs (Zulfiqar, Amir, Amjad, 2010).

Cornea: this is a transparent refractive medium (with highest refractive power) of the eye and resembles a little watch-glass (Khurana et al., 2007).

The cornea epithelium absorbs wavelength between 200 and 315nm, when more of these radiation are absorbed, it results in photochemical damage when the cornea epithelium absorbs these radiations, it can also result to reduction in cells division and in complete death of epithelial cells in severe cases or even corneal ulceration primary short term effects of acute exposure to ultraviolet radiation to the cornea is photokeratitis (Emegwammo, 2011).

Conjunctiva: This is a thin translucent mucous membrane which derives its name from the fact that it joins the eyeball to the lid. It has been found that welders usually suffer from conjunctiva disease such as pinguecula and pterigium (could be degenerative) and conjunctivitis (Ajayi et al., 2011).

Lens: This is a transparent biconvex crystalline structure placed between iris and vitreous in a saucer shaped depression, the patellar fossa. Its diameter is 9 – 10mm and thickness varies with age from 3.5mm at birth to 5mm (Khurana et al., 2007).

The crystalline lens epithelium and nucleus absorbs ultraviolet wavelength between 295nm and 400nm causing lens aging cataracts. Ultraviolet radiations have been reported indirectly absorbed by photosensitizing drugs and cause damage to the crystalline lens, and photo-ophthalmic (Emegwamuo, 2011). Photo-ophthalmic refers to occurrence of multiple epithelial erosion due to the effect of ultraviolet rays especially from 311nm to 290nm.

Vitreous

This is an inner transparent jelly like structure that fills the posterior four-fifth of the cavity of the eye ball and is about four 4ml in volume. It is a hydrophilic gel that mainly serves the optical functions. It mechanically stabilizes the volume of the globe and it’s a pathway for nutrients to reach the lens and retina (Khurana et al., 2007).

The various gels possess UV absorbing chromophores and these results to vitreous shrinkage and denaturation of the collagen network (Emegwamuo, 2011).

Retina: The retina is the innermost tunic of the eye. It is a thin delicate and transparent membrane and the most highly developed tissue of the eye (Khurana et al., 2007).

All welding processes produce radiation in the ultraviolet, visible and infrared spectra which is dangerous to the eye structures. Thermal retinal damage can occur from the infrared radiation (Ajariyeoba et al., 2010).

Ultraviolet light is mainly absorbed by the cornea, lens and is greatly attenuated by the ocular fluids. It does not penetrate the lens and cannot be refracted therefore it does not easily and always cause retinitis. Therefore photochemical injury due to ultraviolet light is mainly limited to the anterior segment of the eye that is conjunctiva and cornea (Zulfiqar et al., 2010).

Photo retinitis is associated with metal welding and cutting, caused by ultraviolet radiation in blue spectrum (400nm – 550nm mean 441.6nm) whereas thermal and photochemical, retina damage is caused by low intensity radiation (Zulfiqar et al., 2010).

Other than welding, photoretinitis can also occur as a result of solar eclipse, observing sun watching in psychiatric disorders, ophthalmic instruments like operating microscope.

The pathogenesis is that the retina is damaged through photochemical effect produced by ultraviolet and visible blue light and thermal effect may enhance the photochemical effects.

These rays are absorbed by the pigment epithelium producing a thermal effect (Khurana et al., 2007).

Therefore, severity of lesions varies directly with the degree of pigmentation of the fundus, duration of exposure and the climatic condition during exposure.

Symptoms includes; persistent of negative after-image of light, progressing later into a positive scotoma and metamorphosis unilateral or bilateral decreased vision (6/12 – 6/60) which develop within 1 – 4 weeks after solar exposure, usually improves to 6/6 – 6/12 within 6 months (Khurana et al., 2007).

Signs: Initially, the fundus may appear normal. Shortly a small yellow spot grey margin may be noted in the fovea and para-fovea region. A typical lesion appears later consisting of a central burnt out hole in the epithelium surrounded by aggregation of mottled pigments.

Primary short term effects of acute exposure to ultraviolet radiation to the cornea is photo retinitis. Its symptoms which occur after a latent period of 6-12 hours include foreign body sensation, lacrimation, chemises blepharospasm (Khurana et al., 2007).

This disappears within 48 hours due to repair mechanism of the epithelium. Long term chronic exposure to UV radiation may be partly responsible for pinguecula, pterigium and band shape keratitis.

Exposure to ultraviolet rays may also increase the skin effect of some industrial chemicals (coal tar and aerosol compounds for example).

Exposure to infrared radiation produced by the electric and other flame cutting equipment may heat the skin surface and the tissue immediately below the surface causing skin burn, in many cases without prior warning.

Photo-ophthalmia which occurs as a result of absorption of UV rays after an interval of 4 – 5 hours (latent period) of exposure to ultraviolet rays, there occur desquamation of corneal epithelium leading to formation of multiple epithelial erosion (Khurana et al., 2007).

Clinical features include severe burning, pain, lacrimation, photophobia, blespharospasm, swelling of palpebral conjunction and retrotarsal folds.

1.1.2 Foreign body injury

Foreign body trauma constitute of at least half of all types of ocular defects. Foreign body may penetrate the eye and become embedded in the globe, usually the common sites are the anterior chamber, the cornea, the vitreous, retina, sclera or choroidaltarsal plate, ciliary muscle, the symptoms vary from little or no discomfort to severe pain (Emegwamuo, 2011).

Subtarsal foreign body

Small foreign body may be washed out of the eye by tears while some become embedded in the tarsal plate and result to corneal abrasion. During combination, the upper lid must be everted.

Superficial foreign body

Corneal foreign body show marked vascular injection around the foreign body. Ocular pain is experienced but difficult to localize. If the foreign body has been there for days, ring infiltration may occur and a small pit ulcer wound remain after removal and foreign body embedded in the conjunction or sclera is often surrounded by hemorrhages.(Brown 2002)

According to Fox (1975) many foreign bodies are metallic, iron particles being most common followed by copper and aluminum. The softer metals (eg magnesium) are the less frequent cause of foreign body injury as they tend to fragment less during drilling, sawing, grinding and cutting. Metallic foreign body embedded in the eye, quickly oxidize in the presence of enzymes of cornea and iris. The oxidation of steel is faster than that of aluminum and magnesium and a rust ring may be apparent.

Intraocular foreign bodies

Small hot foreign body from grinding, simmering or chipping, hitting the eye at great speed may penetrate the globe and seal the route of entry.

Important signs of a perforating injury are;

1. A shallow anterior chamber
2. Eccentricity of the pupil
3. Prolapsed of the iris

Location of the intraocular foreign body may be seen through any of the following method;

1. X – ray
2. Ultrasonography
3. Binocular indirect ophthalmoscope
4. Berman and roper hall localizer, which employs the eccentric current (Emegwamuo, 2011).

Ultrasonography locates the position of nonmetallic fragment while x – rays shows metallic foreign body position. Foreign bodies like gold, silver, platinum, glass and many plastic may be retained without noticeable reaction. Less well tolerated foreign bodies by the eye are nickel, lead, zinc and aluminum particular because they often coated in an inert salt and later encapsulated by fibrous tissue coating rendering them less toxic.

1.2 Eye hazards in welding

Hazard is the risk of harm or danger. It exists in various types and nature.

The following hazards are associated with welding process;

1. Hot slag
2. Metal chips
3. Sparks
4. Hot electrodes
5. Ultraviolet radiation
6. Visible light
7. Infrared light
8. Infrared radiation
9. Fumes and gas..

1.2.1 Protective Eye Wears

Delicate and fragile nature of the eye made them very vulnerable to industrial accident which often leads to loss of one or both eyes. Protective goggles, helmets, hand shields, and masks are designed to completely protect the orbital socket, face, head and neck from floating particles, flying objects, injurious radiations, splashing liquids and intensive light.

A good eye protective wear must have the following requirements;

1. It should be cleaned
2. It should be easily disinfected if need be.
3. Reasonable comfort when worn under designated conditions during welding.
4. Adequate protection against the particular hazards for which they are designed for.
5. It should be durable.
6. It should be clearly marked as safety wear and the manufacturer’s name and trademark intact.
7. It should fit snugly and not interfere with the movement of the wearer.
8. It should be made with non-inflammable or slow burning materials.
9. Provision should be made for those who require the use of corrective lenses to wear safety eyeglasses or goggles containing impact resistant corrective lenses or to wear safety goggles over their regular prescription eyeglasses.

Lenses of eye protection are made of the following materials;

1. Glass Heat toughened, chemically toughened and laminated.
2. Plastics Polymethylmethacrylate (PMMA), cellulose acetate.
3. Wire gauze

Frame or lens housing may be made of;

1. Metal or
2. Plastics

1.3 Statement of problem

Although works has been carried out by various scholars and researchers on the ocular health defects among welders independently and collaboratively. Still there is lack of information on the problems especially in Owerri metropolis, Imo State.

1.3.1 Aim

1. To ascertain possible ocular defects among welders in Owerri Metropolis
2. To determine the association of duration of service and accompanied ocular defects in welders.
3. To ascertain compliance to use of eye protection.

1.3.2 Research questions

1. What are the possible ocular defects among welders in Owerri metropolis?
2. What are the possible association of duration of service and accompanied ocular defects in welders.
3. Do welders comply with the use of eye protection?

1.4 Research hypothesis

The study will be guided by the following hypothesis;

1. Null hypothesis (H_o)

Welding does not pose any threat to vision.

1. Alternative hypothesis (H₁)

Welding poses threat to vision.

1.5 Significance of the study

A number of studies have succeeded in correlating ocular defects with welders. With the ever increasing rate of welding industries in Nigeria, it has become expedient that every possible effort be made to minimize such prevalence in our welding industries. Since it has been shown that vision plays the most important sensory role in welding, we cannot afford to neglect the dangers welding process to the ocular structures among our welders in Nigerian welding industry.

The study will create awareness of ocular health defects in the welding industry and the dangers welding processes poses to welders and will contribute to the history of preventive and environmental optometry as well as industrial management.

1.6 Scope of the study

The works limited to welders of both sex within Owerri metropolis of Imo State.

Pages:  71

Category: Project

Format:  Word & PDF        

Chapters: 1-5

Material contains Table of Content, Abstract and References.