Objective: An in vivo study was done to establish if laser-induced damage o
f the retina could be quantified using fluorescein angiography.
Method This study was carried out on rabbit eyes (n = 6) with an 810 nm dio
de laser (spot diameter: 500 Ir-m, pulse duration: 1 second, power: 100 mW-
400 mW) adapted on a slit lamp. Fluorescence measurements were performed wi
th a fundus camera connected to a fluorescence imaging system. Fluorescence
staining of the retina was evaluated by mathematical modeling. Lesions wer
e correlated to laser parameters and to histologic data.
Results: Image analysis shows that the laser lesions stained progressively.
Fluorescence appears first at the borders of the lesion exhibiting a fluor
escent ring. A progressive increase of the fluorescence into the central zo
ne is observed. The maximum fluorescence intensity into the center of the l
aser spot is obtained after a delay depending on the laser energy. Below 10
0 a 20 mW, lesions are detectable by fluorescence imaging only. A fluoresce
nce plateau appears for a threshold light dose above 200 +/- 20 mW. Mathema
tical modeling demonstrates that quantitative assessment of laser-induced d
amage to the retina is feasible using fluorescence imaging.
Conclusion: The quantification of fluorescence staining in terms of both in
tensity and time can contribute to a better quantification of laser-induced
damage. At last, since laser damage may mimic naturally occurring patholog
y, this method should also be considered to quantify different types of les
ions. Lasers Surg. Med. 24:338-345, 1999. (C) 1999 Wiley-Liss, Inc.