Diagnostic accuracy of confocal scan in detecting acanthamoeba keratitis and fungal keratitis: a systematic review and meta-analysis

Int Ophthalmol. 2023 Aug;43(8):3011-3022. doi: 10.1007/s10792-023-02689-z. Epub 2023 Mar 28.


Purpose: Acanthamoeba keratitis (AK) and fungal keratitis (FK) are two microbial keratitis that cause serious damage and, without early accurate diagnosis and treatment, may lead to blindness. In vivo corneal confocal scan, as an emerging ocular diagnostic method in comparison with microbiological smears and cultures as the gold standard, may assist in accelerating appropriate diagnosis.

Objective: To determine the diagnostic accuracy of confocal scan for the diagnosis of AK and FK.

Methods: Data were collected via a comprehensive literature search of PubMed, Web of Science, Cochrane Library, Embase and Scopus using keywords related to diagnostic accuracy of confocal scan in AK and FK up to October 2022. Pooled data underwent meta-analysis in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic odds ratio (DOR) of confocal scan for the diagnosis of AK and FK.

Results: The final 14 relevant studies were identified, including 1950 eyes. Meta-analysis in AK group revealed 94% sensitivity, 87% specificity, 89% PPV, 92% NPV, and DOR of 143.32, and in FK group disclosed 88% sensitivity, 85% specificity, 85% PPV, 88% NPV, and DOR of 75.98.

Conclusion: The accuracy of confocal scan for the diagnosis of AK was significantly more than that for detecting FK; despite the limitations such as limited numbers of available retrospective studies for the detection of FK, confocal scan had an acceptable performance in detecting FK eyes. The overall performance of NCS was similar with that of HRT-RCM for the detection of both types of keratitis.

Keywords: Acanthamoeba keratitis; Confocal scan; Fungal keratitis; Sensitivity; Specificity.

Publication types

  • Meta-Analysis
  • Systematic Review
  • Review

MeSH terms

  • Acanthamoeba Keratitis* / diagnosis
  • Cornea
  • Corneal Ulcer* / diagnosis
  • Eye Infections, Fungal* / diagnosis
  • Humans
  • Microscopy, Confocal / methods
  • Retrospective Studies