It was the worst case of contact lens-induced infectious keratitis I had ever seen: The female patient, age 14, who reported sleeping in her orthokeratology contact lenses, had severe bilateral red eyes, excessive tearing, extreme corneal edema and such profound photophobia, that my tech wasn’t even able to check her vision before I entered the exam room. Additionally, the young patient complained of blurred vision and pain. When I looked at her with the slit lamp, she had severe and diffuse keratitis in each eye. Also, her anterior chambers had 4+ cell and flare, and I noted severe conjunctival hyperemia with underlying diffuse scleritis. The patient’s entire corneas were both completely ulcerated with widespread and diffuse epithelial and stromal keratitis.

Here, I provide some background on infectious keratitis, two of the more common causes and their respective management, as well as this patient’s specific diagnosis and how she is faring today.

BACKGROUND

Infectious keratitis is inflammation of the cornea via an infectious cause. In the United States, there are 11 cases per 100,000 inhabitants, reports Revista Brasileira de Oftalmologia. Contact lens wear can increase the risk of developing the condition, as infectious keratitis commonly occurs due to patient non-compliance to the proper care schedule (failure to disinfect), overnight wear, swimming while wearing contact lenses or wearing lenses beyond the prescribed amount of approved time.

There are several causes of infectious keratitis associated with contact lenses. They are bacterial, fungal, viral and parasitic (See “Practice Preparations,” p.34).

COMMON CAUSES

Acanthamoeba (AK) (parasitic) and pseudomonas aeruginosa (PAE) (bacterial) are two of the more common serious infectious causes of keratitis seen in contact lens patients.

• AK. This is a free-living amoeba found in air, soil and water (fresh, sea, tap, hot tubs, swimming pools) and takes form as either an active trophozoite or a dormant cyst, which is difficult to kill because of its double wall morphology. The U.S. prevalence of AK is estimated at one to two cases per million contact lens wearers, according to Cornea and the American Journal of Ophthalmology.

Its clinical signs often do not match its host’s symptoms, in that the eye can appear relatively normal at first, though the affected patient will complain of decreased vision, photophobia and severe pain. That said, patients who present with worsening infection (a 4-week to 8-week duration) have anterior chamber inflammation with cell and flare, anterior multifocal infiltrates in the stroma, diffuse keratitis, keratic precipitates, limbal injection, microcystic edema, punctate epithelial erosions, radial neuritis, scleritis, deep stromal keratitis (ring infiltrates in 16% of cases) and a diffuse superficial punctate keratopathy or epithelitis. If a large central corneal ulcer and/or severe anterior chamber reaction with hypopyon is present, referral to a corneal specialist, who will determine whether penetrating keratoplasty is necessary, is warranted.

Of note: AK can masquerade as herpes simplex virus (HSV) keratitis, in that a dendritic pattern may be seen, though the condition lacks HSV’s terminal end bulbs, classic branching and ulceration.

Steroid treatment for a presumed HSV keratitis worsens AK (this can lead to corneal perforation), and antiviral treatment delays the condition’s healing course.

Typically, admission of wearing contact lenses during swimming and showering indicates a high likelihood of AK. In fact, last spring, Iowa eye doctors saw 75 AK patients, the vast majority of whom practiced poor contact lens hygiene and reported water exposure during contact lens wear. (See https://bit.ly/2QLHUUr .)

To achieve a definitive diagnosis, however, corneal scrapings and a corneal culture with Agar should be obtained to identify pathology.

To resolve AK, debridement should be considered, as it helps decrease the bacterial load and number of organisms. Additionally, the following should be prescribed:

• Polyhexamethylene biguanide 0.02%, chlorhexidine acetate 0.02%, brolene 0.1%. These antimicrobials are prescribed concomitantly to kill the amoeba.
• Oral ketoconazole. This antifungal is shown to have some efficacy in decreasing acanthamoeba infections and reducing corneal inflammation, reports Cornea.
• Topical miltefosine. This broad-spectrum antimicrobial drug is effective against an array of parasites, cancer cells and pathogenic bacteria and fungi.

The general recommendation for the aforementioned drugs is dosing started at every one to two hours until improvement, which can take weeks. For drops, alternating is recommended. Dosages are then decreased, but these drugs may still be needed for months, if not a year.

If this treatment course does not alleviate AK, penetrating keratoplasty is considered.

• PAE. This is a type of gram-negative bacteria located in soil and water that has been implicated in both bacterial keratitis and endophthalmitis. It is the most frequent and pathogenic ocular pathogen that can incite corneal perforation in just 72 hours, reports the Sultan Qaboos University Medical Journal.

PAE’s clinical signs are anterior chamber cell/flare, conjunctival injection, corneal edema, a grayish/white focal infiltrate or stromal opacity with epithelial defect that stains with NaFl (PAE can involve the entire cornea), hypopyon, lid edema, mucopurulent exudate and a yellow coagulative necrosis. Additionally, a ring infiltrate of perineural involvement is possible. Personally, I’ve found that PAE presents as a “soupy” cornea.

Referral to a corneal specialist should be considered when PAE keratitis is located in the central axis and progressing after a failed treatment plan, as these characteristics indicate improper diagnosis and treatment.

PAE symptoms are decreased vision, significant pain and photophobia and corneal swelling.

Arriving at a definitive diagnosis requires corneal scraping and culturing. (As a brief, yet related, aside, slit lamp photos should be obtained to document the infection’s size to help monitor its healing.)

While awaiting culture results, a fourth-generation fluoroquinolone should be prescribed for use every 30 minutes to every one hour, alternated with a broad-spectrum gram (-) and gram (+) antibiotic, used empirically, with a topical cycloplegic for pain. This frequent dosing should be followed until clinical improvement, monitored daily, occurs. Upon improving signs and symptoms, the frequency can be decreased.

When faced with a severe case (e.g. worsening pain, worsening clinical signs, sight-threatening infections in the visual axis, late stage clinical findings as noted above, etc.), prescribing oral antibiotics as an additional anti-infective treatment to compliment the topical treatments should be considered. Once improved signs and symptoms are noted, topical steroids should be considered, as they help decrease inflammation and pain and may have benefits in reducing corneal scarring, reports the Steroids for Corneal Ulcers trial.

Fortified tobramycin dosed 12.5 mg/ml is an effective and potent means of delivering strong compounded anti-infective treatments in severe cases, according to the Indian Journal of Ophthalmology. This offers broad spectrum coverage and is usually done in combination with other topical anti-infectives.

Punctal occlusion is ideal for PAE patients who have a sight-threatening infection, as it provides increased residence time and penetration of a topical anti-infective drug.

Should the patient fail to respond to treatment, referral to a corneal specialist for consideration of a penetrating keratoplasty should occur. This form of keratitis can result in corneal perforation or descemetocele.

THAT PATIENT

The patient mentioned above was diagnosed with bilateral AK. Prior to seeing me, three other eye doctors diagnosed her as having bilateral HSV keratitis, for which they had prescribed topical antiviral treatment and a topical steroid. Both worsened the AK.

The patient’s extensive loss of vision, as a result of the prolonged and worsened infection, caused her to miss half of her freshman year of high school, and she required an eventual penetrating keratoplasty in one eye.

As such patients require treatment for months and, sometimes, years after the initial infection, I continue to follow her. I am happy to say she is doing well. In fact, because of this patient’s many office visits, she developed a deep bond with our staff, and she now volunteers as an intern with us. OM

DR. JOHNSTON practices at Georgia Eye Partners. He focuses on ocular surface disease and has extensive experience in co-managing cataract and refractive surgery patients. He is a consultant and speaker for Abbott, Alcon, Allergan, BioTissue and Shire. Email him at drj@gaeyepartners.com.