Abstract
Purpose:
Near-infrared fundus autofluortescence (NIRAF) is considered to be the manifestation of melanin and its analogs, however, little is known about its clinical utility. The aim of this present study was to comprehend the specific characteristics of NIRAF by analyzing the finding of retinal pigment epithelium (RPE) tears occurring in eyes with exudative age-related macular degeneration (AMD).
Methods:
This study included 7 eyes of 7 Japanese patients (1 eye of 1 female, 6 eyes of 6 males; mean age: 77.4 years) with AMD which were thought to have an RPE tear that occurred during the monthly treatment with intravitreal ranibizumab injection (IVR). NIRAF (excitation: 789 nm, barrier: 800 nm) examinations were performed with a confocal scanning ophthalmoscope (Heidelberg Retina Angiograph 2; Heidelberg Engineering, Dossenheim, Germany) within 3 months after the occurrence of the RPE tear. Qualitative evaluation of the autofluorescence findings at the RPE defects, the rolled RPE, and the unaffected areas outside the lesion was performed to clarify the specific characteristics of NIRAF. Simultaneously, to verify the choroidal contribution to NIRAF, the gray levels (GL) of the autofluorescence signal at the RPE defects and the unaffected areas were analyzed quantitatively using Image J software.
Results:
The RPE tear occurred after undergoing IVR an average of 1.29 times (range: 1 to 2 times). Qualitatively, all RPE defects (7 eyes, 100%) showed hypoautofluorescence (hypoAF) in the shape of choroidal vessels and distinct hyperautofluorescence (hyperAF) from the extravascular choroidal stroma. Of the 7 eyes, the rolled RPE in 5 eyes (71.4%) demonstrated heterogeneous hyperAF, and the unaffected areas of 4 eyes (57.1%) showed faint hypoAF in the shape of choroidal vessels. In the quantitative analysis, the GL ratio of RPE defect to the unaffected area was 0.88.
Conclusions:
NIRAF has a characteristic to visualize the cumulative autofluorescence signals of melanin in RPE cells. The choroidal contribution of NIRAF in the Japanese cases in this study was larger than that of the previous report involving Western subjects (e.g., 0.71: Keilhauer and Delori. IOVS. 2006), thus suggesting that, at least in the Japanese eyes, the choroidal stroma contribution is relatively high. NIRAF has the potential to be a novel imaging modality of choroid.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
452 choroid •
701 retinal pigment epithelium