Role of confocal microscopy in the diagnosis of fungal and acanthamoeba keratitis.
OBJECTIVE
To investigate the role of confocal microscopy as a diagnostic modality in microbial keratitis and to determine inter- and intraobserver variation in the analysis and interpretation of confocal microscopy findings.


METHODS
Prospective, double masked, nonrandomized, observational clinical trial.


METHODS
We included 146 consecutive patients with clinically suspected microbial keratitis.


METHODS
Confocal microscopy and microbiology evaluation of study participants.


METHODS
Sensitivity, specificity, and positive and negative predictive values of confocal microscopy in diagnosing fungal and Acanthamoeba keratitis compared with microbiologic evaluation, as well as the intra- and interobserver variation in interpretation of confocal scans.


RESULTS
We included 148 cases of infiltrative keratitis. Of the 103 microbiologically proven cases of Acanthamoeba or fungal keratitis, the confocal microscope was able to identify fungal filaments or Acanthamoeba cysts in 91 cases with either fungal or Acanthamoeba keratitis with a sensitivity of 88.3% (95% confidence interval [CI], 82.2-94.5) and a specificity of 91.1% (95% CI, 82.8-99.4). The interobserver agreement in interpreting the scans was good (kappa = 0.6; phi = 0.617). The intraobserver agreement was kappa = 0.795 and phi = 0.807.


CONCLUSIONS
The confocal microscope seems to be an accurate and reliable diagnostic modality in the etiologic diagnosis of fungal and Acanthamoeba keratitis.
Vaddavalli
Pravin K
PK
Cornea and Anterior Segment Service, L V Prasad Eye Institute, Hyderabad, India. pravin@lvpei.org
Garg
Prashant
P
Sharma
Savitri
S
Sangwan
Virender S
VS
Rao
Gullapalli N
GN
Thomas
Ravi
R
D015823:Acanthamoeba Keratitis / Q000175:diagnosis* / Q000469:parasitology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003320:Corneal Ulcer / Q000175:diagnosis* / Q000382:microbiology; D004311:Double-Blind Method; D015821:Eye Infections, Fungal / Q000175:diagnosis* / Q000382:microbiology; D005189:False Positive Reactions; D005260:Female; D005658:Fungi / Q000302:isolation & purification; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009181:Mycoses / Q000175:diagnosis* / Q000382:microbiology; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult