Purpose:
To demonstrate efficacy of the two-photon ophthalmoscope in aiding diagnosis of difficult keratitis cases. A case series is presented here.
Methods:
The two-photon ophthalmoscope (25 and 50 mW laser source from Heidelberg, Germany) was utilized to image slides from corneal scrapings on a series of patients.
Results:
The two-photon ophthalmoscope aided in the diagnosis of all patients. Fungal, bacterial, Microsporidial, and culture-negative keratitis cases are discussed. The first case is a contact lens wearer who developed severe keratitis and was treated for Pseudomonas. Two-photon imaging showed cocci-shaped organisms (see left photo) and subsequently cultures grew out Strep pneumoniae. A second case of an immunocompromised patient is discussed. He presented with a four month history of keratitis and was treated presumptively for herpes. Two-photon imaging showed a large organism, which grew out Fusarium in culture two weeks later (see right photo). Another interesting case is discussed of a non-healing severe keratitis for 9 mos, presumed Acanthamoeba. Two-photon imaging showed a small organism of <5 u which the CDC confirmed as E. hellum by PCR testing.Other cases are demonstrated, including two cases of negative two-photon imaging, in which the patients were found to have been abusing tetracaine.
Conclusions:
The two-photon ophthalmoscope has great promise in aiding diagnosis in difficult cases of infectious keratitis. Current culture techniques require days to weeks for results, if an organism is even identified. Our early work shows that once approved for human use, this device can noninvasively acquire selective high-resolution structural and functional information from the cornea. Early diagnosis and proper treatment of these devastating corneal infections are crucial to saving sight.
Keywords: keratitis • microscopy: confocal/tunneling • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)