8 Chemical-induced ocular side effects

Class: Acids

Generic name: 1. Hydrofluoric acid; 2. hydrochloric acid; 3. sulfuric acid.

Synonyms: 1. Fluoric acid, fluohydric acid, hydrofluoride, fluorine monohydride; 2. hydrogen chloride, muriatic acid; 3. battery acid, sulfuric acid, hydrogen sulfate, sulfine acid.

Proprietary names/products containing: 1. Eagle

One Chrome and Wire Cleaner, Ultradent Porcelain Etch, FPPF Acid Enhanced Trailer Brightener, Whink Rust Remover, Arrobrite Aluminum Brightener, Briter 601 Glass Cleaner;

2. Lysol Brand Toilet Bowl Cleaner, Humidifier Plastic Cleaner, Febreze Laundry Odor Eliminator, Lime A Way Toilet Bowl Cleaner, Zep Grout Cleaner and Whitener, Zep Calcium, Lime, and Rust Stain Remover, C Flux (Lead Free) maintenance paste, Kem Tek Calcium & Metal Eliminator, Kem Tek Tile & Spa Cleaner, Parks Muriatic Acid 20%.; 3. Rain Away Rain Repellent, Naval Jelly Rust Dissolver, Loctite Sink Jelly, Goddards Silver Dip, Instant Power Liquid Drain Opener, Duro Aluminum Jelly Corrosion Remover, pH Down, pH Adjust

Primary use

Hydrofluoric acid

This compound is used to clean and etch glass and metal in the manufacture of silicone wafers and in the synthesis of many fluorine-containing organic compounds, including teflon and ­refrigerants such as freon. It is also used in many household rust removers.

Hydrochloric acid

Sold as muriatic acid, this is used for a variety of household, scientific research and construction purposes. Hydrochloric acid is also used to clean and electroplate metal, and to tan leather. It is used to adjust pH in many products.

Sulfuric acid

A principal component in the manufacture of batteries, this is also used in the fertilizer, petroleum refining and printing ­industries as well as in metal cleaning and electroplating and in the paper industry.

Ocular side effects

Direct ocular exposure

Certain 

1. Ocular irritation a. Eye pain

2. Lacrimation

3. Non-specific blepharospasm

4. Conjunctiva

a.Hyperemia

b.Edema

c.Blanching of vascular bed

d.Symblepharon

5. Cornea

a.Edema

b.Scarring

c.Ulceration

d.Vascularization

e.Perforation

f . Fibrovascular pannus 6. Entropion

7. Iritis

Possible

1. Cataracts

2. Increased intraocular pressure

Clinical significance

In general, acids are less injurious to the eye than alkalis. As is the case for alkalis, concentration, time and surface area of exposure, and pH are the factors which most influence the extent of the injury. Once the pH drops to 2.5 or below the extent of injury is likely to be much more severe. Hydrofluoric, hydrochloric and sulfuric acids can all cause extensive corrosive damage, initially from the high concentration of hydrogen ions. However, hydrofluoric acid is considered the acid most likely to cause ­severe ocular and skin injuries.

Most acids cause a coagulative necrosis of the corneal epithelium, which helps to prevent penetration of the acid into the deeper layers of the cornea or the anterior chamber. With hydrofluoric acid, the fluoride ion itself can penetrate the cornea and cause severe damage. In fact, the ability of the free fluoride ion to penetrate tissue and combine with internal body calcium stores makes splash exposures potentially fatal. Hypocalcemia may ensue in cases where less than 10% of the body surface area has been exposed to hydrofluoric acid, causing cardiac arrhythmia and bone damage.

The ocular injury pattern for hydrofluoric and other concentrated acids is very similar to that for alkalis. A higher concentration and longer exposure time may be needed to achieve the same degree of injury, but the same types of injury are possible, including corneal and conjunctival scarring, and symblepharon formation.

Recommendations

The most important intervention in ocular exposure to concentrated acids is immediate irrigation. Many studies have been done to identify the optimal irrigating solution for various types of chemical exposure, but the subtle advantages of one solution