Orthokeratology lens-related Acanthamoeba keratitis: case report and analytical review

Abstract

Acanthamoeba keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Contact lens use is the main risk factor for AK. The orthokeratology (OK) lens, a specially designed contact lens, has been used worldwide as an effective method of myopia control. However, the OK lens is associated with an increased risk of Acanthamoeba infection. Many primary practitioners are concerned about this infection because of its relative rarity, the lack of promising therapeutic medications, and the need for referral. We herein report two cases of AK associated with OK lenses, present a systematic review of such cases, and discuss the possible reasons for the higher incidence rate of this infection in patients who wear OK lenses. We combined the clinical knowledge and skills of corneal specialists and lens experts with the sole objective of addressing these OK lens-related AK cases. We found that the most common risk factors were rinsing the lenses or lens cases with tap water. Prompt and accurate diagnosis along with adequate amoebicidal treatment are essential to ensure desirable outcomes for OK lens wearers who develop AK. Appropriate OK lens parameters and regular checkups are also important.

Keywords: Acanthamoeba keratitis; biguanides; diamidines; myopia control; ocular infection; orthokeratology; rigid contact lens.

Figure 1.

Case 1. (a, b) Slit-lamp examination revealed a corneal infiltrate measuring 2 × 2 mm with fluorescent staining. (c) Confocal laser microscopy revealed structures highly resembling the amoebic cyst (red arrow). (d, e) Resolution of the ulcer was noted after 4 days of treatment. (f) Amoebic cysts were still found by confocal microscopy (red arrows). (g) A punctate corneal epithelial defect was noted at the 1-month visit. (red arrow), but (h) no amoebic cysts were found. (i) A mild corneal opacity was present at the 70-day visit. Bar = 50 microns.

Figure 2.

Case 2. Slit-lamp examination revealed (a) stromal edema and (b) a corneal ulcer measuring 2 × 2 mm with fluorescent staining. (c) Confocal laser microscopy revealed structures highly resembling amoebic cysts in the ulcer. After 7 days of treatment, (d) the corneal edema had subsided and (e) fluorescein staining was weakly positive. (f) The ulcer had healed with a small corneal opacity at the 2-month visit. Bar = 50 microns.