Differentiation of acanthamoeba keratitis from other non-acanthamoeba keratitis: Risk factors and clinical features

Abstract

Introduction: Infectious Keratitis is one of the most common ocular emergencies seen by ophthalmologists. Our aim is to identify the risk factors and clinical features of Acanthamoeba Keratitis (AK).

Methods: This retrospective chart review study was conducted at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, and included all the microbial keratitis cases, male and female patients of all ages. The main outcome is the differentiation between various microbial keratitis types.

Results: We included 134 consecutive eyes of 126 persons. We had 24 cases of acanthamoeba keratitis, 22 bacterial keratitis, 24 fungal keratitis, 32 herpetic keratitis, and 32 bacterial co-infection. Contact lens wear was found in 33 eyes (24.6%). Among acanthamoeba keratitis patients, 73% were ≤ 39 years of age, and 73% were females (P <0.001). Also, in AK cases, epithelial defect was found in all cases (100%), endothelial plaques were found in 18 eyes (69.2%), 12 cases had radial keratoneuritis (46.2%), and ring infiltrate was found in 53.8% of AK cases.

Conclusions: We determined the factors that increase the risk of acanthamoeba infection and the clinical characteristics that help distinguish it from other types of microbial keratitis. Our findings suggest that younger females and patients who wear contact lenses are more likely to develop acanthamoeba keratitis. The occurrence of epitheliopathy, ring infiltrate, radial keratoneuritis, and endothelial plaques indicate the possibility of acanthamoeba infection. Promoting education on wearing contact lenses is essential to reduce the risk of acanthamoeba infection, as it is the most significant risk factor for this infection.

Fig 1

Slit-lamp photograph showing ring infiltrate lesion associated with acanthamoeba keratitis (A); Slit-lamp photograph showing retro-corneal plaques (endothelial plaques) lesion associated with acanthamoeba keratitis (B).

Fig 2

Slit-lamp photographs showing epitheliopathy lesion associated with acanthamoeba keratitis (A); fluorescein stain highlighting the epitheliopathy lesion (B).

Fig 3. Comparison of significant clinical signs in acanthamoeba keratitis and non-acanthamoeba keratitis.

RCP: Retro Corneal Plaques; EP: Endothelial Plaques; RKN: Radial Keratoneuritis; PN: Perineuritis; Non-AK: Non-Acanthamoeba Keratitis; AK: Acanthamoeba Keratitis.

Fig 4

Slit-lamp photograph showing retro-corneal plaques (endothelial plaques) lesion associated with acanthamoeba keratitis showing more demarcated margins (yellow mark) (A); Retro-corneal plaques (Endothelial Plaques) in AS-OCT, fungal keratitis-associated endothelial plaques showing the absence of space (red arrows) and more demarcated margins (yellow mark) (B).