Keratopathy

Jacky Y.T. Yeung
Stephanie Baxter


BASICS


DESCRIPTION


• There are 2 broad categories of crystalline keratopathy:


– Infectious type


– Deposition type


• When discussing crystalline keratopathy, it is generally accepted that one is referring to the infectious type, unless otherwise stated.


– Synonym: Infectious crystalline keratopathy (ICK)


• Branching, crystalline corneal opacity caused by interlamellar colonization by microorganisms without significant adjacent stromal inflammation


EPIDEMIOLOGY


Incidence


Unknown, uncommon


RISK FACTORS


• Corneal graft


• Chronic topical steroid use


• Refractive surgery


• Contact lens wear


• Topical anesthetic abuse


• Acanthamoeba keratitis (co-infection)


• Prior herpes simplex virus (HSV) keratitis


• Systemic immunosuppression


GENERAL PREVENTION


• Prudent steroid use


• Routine follow-up


PATHOPHYSIOLOGY


Implantation and colonization of interlamellar spaces by microorganisms. The organisms are typically nonvirulent bacterial and fungal species. Extracellular matrix secretion and biofilm formation mask the antigenic stimuli and likely contribute to the characteristically scarce inflammatory response, in conjunction with the anti-inflammatory effects of steroids.


ETIOLOGY


Streptococcus viridans (α-hemolytic)


• Candida sp


• Nontuberculous mycobacteria


• Other gram-positive and gram-negative bacteria may be polymicrobial


COMMONLY ASSOCIATED CONDITIONS


Corneal transplantation


DIAGNOSIS


HISTORY


Typically insidious onset of vision loss and/or identification of a corneal opacity in the setting of known risk factors


PHYSICAL EXAM


• White, branching, crystalline opacity in the anterior stroma


• Lack of significant inflammation


• Slow expansion


• Rarely keratic precipitates or anterior chamber cells if posterior location


DIAGNOSTIC TESTS & INTERPRETATION


Lab


Initial lab tests

• Corneal scraping


– Send for culture and sensitivity


• Lamellar biopsy


– Send for culture and sensitivity and histopathology


• Consider lipid profile (Schnyder’s crystalline dystrophy) and protein electrophoresis (monoclonal gammopathies)


Follow-up & special considerations

• Routine culture growth often unsuccessful:


– May require specific nutrient (pyridoxal) for viridans streptococci (1)


– Lowenstein–Jensen agar for isolation of nontuberculous mycobacteria


• If cystinosis is suspected, examine conjunctival biopsy, WBCs, or bone marrow for cystine crystals.


• If Bietti crystalline corneoretinal dystrophy is suspected, do visual fields and electroretinography.


Imaging


• Anterior segment photography


• Corneal optical coherence tomography, laser confocal microscopy


Diagnostic Procedures/Other


• Ocular evaluation:


– Polymerase chain reaction of corneal scrapings


• Systemic evaluation:


– CBC and differential


– Protein electrophoresis


– Lipid profile


– Uric acid


– Bone marrow aspiration


Pathological Findings


ICK – anterior stroma shows distended interlamellar spaces filled with microorganisms and without significant adjacent inflammation


DIFFERENTIAL DIAGNOSIS


• Infectious keratitis:


– Bacterial – ICK


– Fungal


– Viral


– Protozoan – Acanthamoeba


• Deposition:


– Acquired immunoprotein keratopathies – multiple myeloma, essential cryobulinemia, and other monoclonal gammopathies


– Lipid keratopathies – Schnyder’s crystalline dystrophy, Tangier disease, familial lipoprotein disorders


– Drugs deposition – ciprofloxacin, chrysiasis, chloroquine, chlorpromazine


– Errors of protein metabolism – cystinosis, tyrosinemia, hyperuricemia, gout


– Miscellaneous dystrophies and metabolic abnormalities – posterior crystalline corneal dystrophy, Bietti crystalline corneoretinal dystrophy, calcium deposition, porphyria, oxalosis


TREATMENT


MEDICATION


First Line


• Tailor treatment is performed according to specific organism if known.


• Duration of treatment often requires weeks to months with slow taper.


• Bacterial:


– Depending on severity of disease, consider broad spectrum fluoroquinolones (e.g., gatifloxacin, moxifloxacin) as initial therapy


• May also add/replace with:


– Gram +ve: cefazolin 50 mg/mL or vancomycin 25–50 mg/mL 1gtt per 1 h


– Gram –ve: gentamicin or tobramycin 14 mg/ml 1gtt per 1 h


– See the chapter on Bacterial Keratitis.


• Fungal:


– Amphotericin B 0.15% or voriconazole 0.5–1% per 1 to 2 h drops for Candida


– See the chapter on Fungal Keratitis.


Second Line


May consider systemic antibacterial or antifungal agents if refractory to topical treatment


ADDITIONAL TREATMENT


General Measures


Suspend immunosuppressive medication (e.g., topical steroids) if possible


Additional Therapies


Possible Nd:YAG laser for crystal disruption of ICK (2)


SURGERY/OTHER PROCEDURES


• Early surgical debridement and culture are advised, especially for post-LASIK patients.


• Full thickness or partial thickness anterior lamellar keratoplasty may be required for severe and/or refractory cases.


ONGOING CARE


FOLLOW-UP RECOMMENDATIONS


• Long-term follow-up required for treatment failure:


– Corneal graft follow-up: Possible rejection or recurrence


PROGNOSIS


Guarded due to chronic, recurrent nature of most crystalline keratopathies


COMPLICATIONS


Failure or rejection of corneal graft



REFERENCES


1. Ormerod LD, Ruoff KL, Meisler DM, et al. Infectious crystalline keratopathy. Role of nutritionally variant streptococci and other bacterial factors. Ophthalmology 1991;98:159–169.


2. Masselos K, Tsang HH, Ooi JL, et al. Laser corneal biofilm disruption for infectious crystalline keratopathy. Clin Experiment Ophthalmol 2009;37(2):177–180.

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Keratopathy

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