Global Health Asia-Pacific Issue 2 | 2024 Issue 2 | 2024 | Page 12

You Ask , They Answer

Q

: What ’ s infectious keratitis , or corneal ulcer , and what are its telltale signs ?

A

: This is a microbial infection of the cornea ( the transparent tissue in the front of the eye that light passes through ). Corneal ulcers can potentially involve all three layers of the cornea — the superficial epithelium , the stroma , and the endothelium — although it may start superficially from the epithelium . There could also be reactive inflammation in the anterior ( front ) chamber of the eye .
Telltale signs include a red eye , decreased vision ( persistent and not improved with blinking or with best corrected glasses ), and often irritative symptoms like pain , watery eye , discharge , lid swelling , or light sensitivity . Some patients can see a white spot ( or corneal abscess ) in the cornea when looking in the mirror .

Q

: Can the condition lead to vision problems or blindness ?

A

: Many cases of severe corneal ulcers can lead to blindness if not treated . It is an ocular emergency when suspected .

Q

: What are the most effective treatments for corneal ulcer ?

A

: Bacterial corneal ulcers ( most common ) need round the clock topical antibiotics , sometimes systemic antibiotics . The drops may need to be administered every hour or half hour in the first forty-eight hours until clinical improvement . This tends to involve either daily or near daily visits to the clinic or admission to the ward .
Fungal corneal ulcers are very difficult to treat and may involve months of treatment with anti-fungal eyedrops .
Amoebic corneal ulcers are also very difficult to treat and always involve months of treatment with anti-amoebic disinfectants .
Viral ulcers , such as those due to herpes simplex , can be treated with topical antiviral eyedrops . Ulcers due to varicella zoster ( shingles ) should be treated with anti-virals topically as well as systemically . Some cases of deeper corneal ulcers would require anti-inflammatory medications as well .
In any of these cases , if there is severe corneal scarring , an optical corneal graft could be necessary later after the infection is controlled . Rarely , if antibiotics are unable to control the infection and there is risk of cornea perforation , an emergency tectonic corneal graft may be needed .

Q

: How can people prevent the condition ?

A

: There are two main types of corneal ulcers . The most common ulcers are those related to gram-negative bacteria , such as Pseudomonas bacteria , which occurs in contact lens wearers .
To prevent such infections , there should be proper storage and meticulous lens cleaning with the right technique ( such as rubbing on palm ) and solutions . Lenses should not be worn overnight , when sleeping , swimming , or showering . Do not wear expired lenses or wear them for extensive hours or whenever the eye feels uncomfortable . Extended wear soft contact lenses ( e . g ., monthly lenses ) are commonly implicated in corneal ulcers .
Corneal infection following corneal abrasion , corneal foreign bodies , or trauma is relatively less common in developed countries but do wear protective eyewear when performing high risk activities ( occupational or leisure ).
Another type of corneal ulcer is common in older people with poor ocular surface . Very often , the infection is caused by gram-positive bacteria in the eyelids which have accumulated to excessive quantities . These people may have inflammed eyelids , inturning or ingrowing eyelashes , called trichiasis , and often dry eye or corneal epithelial problems such as severe dry eye . The risk is increased if patients are on long-term steroidal medications for any reason .
Eyelid warming , care , and hygiene are important . Ophthalmologists can help to remove aberrant eyelashes that rub against the cornea , or surgery can be performed to correct eyelid malpositions such as entropion ( inturning eyelids ).
Professor Louis Tong
Professor Louis Tong is an ophthalmologist at the Singapore National Eye Centre .
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