Indocyanine Green Dye Angiography Research Articles

The Utility of Indocyanine Green Dye Fluorescence Lymphography and Angiography During Wide Excision of Cutaneous Melanoma.

Background and Objectives. Lymph node status is the most important prognostic factor in cutaneous melanoma patients. Recent studies showed that indocyanine green (ICG) fluorescence lymphography helps locating sentinel nodes better. Sometimes, flap reconstruction is needed after wide excision of tumor. Indocyanine green fluorescence also simplifies the intraoperative design of flaps. This study investigates the use of ICG fluorescence in patients with cutaneous melanoma during operation. Methods. We performed a single-center, retrospective study of subjects with cutaneous melanoma using ICG lymphograhy and/or angiography during wide excision of tumor between 2015 and 2019. Patients received a dermal injection of ICG and patent blue (PB) dye. The positive node was excised. Indocyanine green angiography was utilized to visualize better skin paddle during flap reconstruction if needed. Results. A total of 37 sentinel lymph nodes (SLNs) were removed in 12 patients. Indocyanine green successful localization was found in 10 of the 12 patients (83%). Three patients were found with 6 metastatic nodes on final pathology. 100% of these 6 nodes were identified by ICG, while 83% (5/6) were positive PB. Three of the 12 patients received flap reconstruction after operation, and no major complications occurred. Conclusions. ICG dye lymphangiography is a good alternative for locating SLNs in patients with melanoma. It could also visualize well perfusion skin paddle during reconstruction. We reported a reproducible and simple method to utilize ICG fluorescence in cutaneous melanoma patients.

An Inconvenient Truth of Clinical Assessment of Indeterminate Burns and Indocyanine Green Dye Angiography Precise Marking for Burn Excision: A Prospective, Multicentered, Triple-Blinded Study

An Inconvenient Truth of Clinical Assessment of Indeterminate Burns and Indocyanine Green Dye Angiography Precise Marking for Burn Excision: A Prospective, Multicentered, Triple-Blinded Study

Dynamic analysis of maxillary perfusion during Le Fort I osteotomy using indocyanine green

The aim of this study was to evaluate the dynamic perfusion of the maxilla during various stages of a Le Fort I osteotomy using indocyanine green (ICG) dye angiography. This was a retrospective evaluation of patients who underwent a Le Fort I osteotomy. ICG was used to assess perfusion at specific time points during the procedure. Twenty-four patients underwent a Le Fort I osteotomy with dynamic perfusion ICG angiography. Statistically significant differences in perfusion were noted at all three locations assessed between preoperative (T0), post down-fracture (T1), and postoperative (T2) time points. When controlling for mean arterial pressure, statistically significant differences were noted at all three locations assessed between T0 and T1, and between T0 and T2. There were no statistically significant differences in patient age, heart rate, preservation or sacrifice of the descending palatine arteries, or conventional vs. segmental Le Fort I osteotomies across T0, T1, and T2. In conclusion, there was a statistically significant decrease in perfusion, as assessed by intraoperative dynamic angiography, to the anterior maxilla following maxillary down-fracture. Patient age, conventional vs. segmental Le Fort I osteotomy, changes in mean arterial pressure and/or heart rate, and preservation of the descending palatine vessels had no statistically significant effect on perfusion.

Assessing value in breast reconstruction: A systematic review of cost-effectiveness studies

Breast reconstruction is one of the most common procedures performed by plastic surgeons and is achieved through various choices in both technology and method. Cost-effectiveness analyses are increasingly important in assessing differences in value between treatment options, which is relevant in a world of confined resources. A thorough evaluation of the cost-effectiveness literature can assist surgeons and health systems evaluate high-value care models. A systematic review of PubMed, Web of Science, and the Cost-Effectiveness Analysis Registry was conducted. Two reviewers independently evaluated all publications up until August 17, 2017. After removal of duplicates, 1996 records were screened, from which 53 studies underwent full text review. All the 13 studies included for final analysis mention an incremental cost-effectiveness ratio. Five studies evaluated the cost-effectiveness of technologies including acellular dermal matrix (ADM) in staged prosthetic reconstruction, ADM in direct-to-implant (DTI) reconstruction, preoperative computed tomography angiography in autologous reconstruction, indocyanine green dye angiography in evaluating anastomotic patency, and abdominal mesh reinforcement in abdominal tissue transfer. The remaining eight studies evaluated the cost-effectiveness of different reconstruction methods. Cost-effective strategies included free vs. pedicled abdominal tissue transfer, DTI vs. staged prosthetic reconstruction, and fascia-sparing variants of free abdominal tissue transfer. Current evidence demonstrates multiple cost-effective technologies and methods in accomplishing successful breast reconstruction. Plastic surgeons should be well informed of such economic models when engaging payers and policymakers in discussions regarding high-value breast reconstruction.

Laser-Assisted Indocyanine Green Dye Angiography for Postoperative Fistulas After Salvage Laryngectomy

Pharyngocutaneous fistula formation is an unfortunate complication after salvage laryngectomy for head and neck cancer that is difficult to anticipate and related to a variety of factors, including the viability of native pharyngeal mucosa. To examine whether noninvasive angiography with indocyanine green (ICG) dye can be used to evaluate native pharyngeal vascularity to anticipate pharyngocutaneous fistula development. This cohort study included 37 patients enrolled from June 1, 2013, to June 1, 2016, and follow-up was for at least 1 month postoperatively. The study was performed at the University of Alabama at Birmingham, a tertiary care center. Included patients were those undergoing salvage total laryngectomy who were previously treated with chemoradiotherapy or radiotherapy alone. The ICG dye was injected intraoperatively, and laser-assisted vascular imaging was used to evaluate the native pharyngeal mucosa after the ablative procedure. The center of the native pharyngeal mucosa was used as the reference to compare with the peripheral mucosa, and the lowest mean ICG dye percentage of mucosal perfusion was recorded for each patient. The primary outcome was the formation of a postoperative fistula, which was assessed by clinical and radiographic assessment to test the hypothesis formulated before data collection. A total of 37 patients were included (mean [SD] age, 62.3 [8.5] years; 32 [87%] male and 5 [14%] female); 20 had a history of chemoradiotherapy, and 17 had history of radiotherapy alone. Thirty-four patients (92%) had free flap reconstruction, and 3 had primary closure (8%). Ten patients (27%) developed a postoperative fistula. No significant difference was found in fistula rate between patients who underwent neck dissection and those who did not and patients previously treated with chemoradiotherapy and those treated with radiotherapy alone. A receiver operator characteristic curve was generated to determine the diagnostic performance of the lowest mean ICG dye percentage of mucosal perfusion determined by fluorescence imaging, which was found to be a threshold value of 26%. The area under the curve was 0.85 (95% CI, 0.73-0.97), which was significantly greater than the chance diagonal. The overall mean lowest ICG dye percentage of mucosal perfusion was 31.3%. The mean lowest ICG dye percentage of mucosal perfusion was 22.0% in the fistula group vs 34.9% in the nonfistula group (absolute difference, 12.9%; 95% CI, 5.1%-21.7%). Patients who developed postoperative fistulas had lower mucosal perfusion as detected by ICG dye angiography when compared with patients who did not develop fistulas.

Utilizing Indocyanine Green Dye Angiography to Detect Simulated Flap Venous Congestion in a Novel Experimental Rat Model.

Venous congestion is a leading cause for free flap failure and still relies on clinical observation as the diagnostic gold standard. We sought to characterize blood flow in a variable venous congestion murine hind limb model using indocyanine green (ICG, SPY Pack, LifeCell, Branchburg, NJ) angiography. Male Sprague-Dawley rats (Charles River, Hudson, NY) underwent bilateral partial amputation at the inguinal ligament, leaving only the femoral vessels and femur intact. Complete unilateral venous occlusion was achieved via suture ligation, while partial occlusion was achieved by surrounding the femoral vein with a synthetic microtube to achieve 25, 75, 85, or 92% occlusion. Relative blood flow of occluded and control limbs was tracked with ICG angiography throughout a 90-minute time course. ICG angiography detected statistically significant (p < 0.05) reductions in limb blood flow 1 and 2 minutes following ICG injection in the 100, 92, and 85% occluded limbs when compared with contralateral control limbs. Dynamic tracking using the slope of ICG inflow for 45 seconds postinjection reflected this same significant difference. No statistically significant change in limb blood flow or dye influx rate was observed in the 25 and 75% occlusion groups. ICG angiography can detect venous congestion in a rat lower extremity model reliably at occlusion rates ≥ 85%. This method may offer surgeons an intraoperative diagnostic tool to identify venous congestion at extremely early time points, allowing for immediate intervention. Further investigation and characterization is warranted in a larger animal model before clinical adaptation.

ICG angiography predicts burn scarring within 48 h of injury in a porcine vertical progression burn model

The current standard of care in determining the need to excise and graft a burn remains with the burn surgeon, whose clinical judgment is often variable. Prior work suggests that minimally invasive perfusion technologies are useful in burn prognostication. Here we test the predictive capabilities of Laser Doppler Imaging (LDI) and indocyanine green dye (ICG) angiography in the prediction of burn scarring 28 days after injury using a previously validated porcine burn model that shows vertical progression injury. Twelve female Yorkshire swine were burned using a 2.5×2.5cm metal bar at variable temperature and application times to create distinct burn depths. Six animals (48 injuries total) each were analyzed with LDI or ICG angiography at 1, 24, 48, and 72h following injury. A linear regression was then performed correlating perfusion measurements against wound contraction at 28 days after injury. ICG angiography showed a peak linear correlate (r2) of .63 (95% CI .34 to .92) at 48h after burn. This was significantly different from the LDI linear regression (p<.05), which was measured at r2 of .20 (95% CI .02 to .39). ICG angiography linear regression was superior to LDI at all timepoints. Findings suggest that ICG angiography may have significant potential in the prediction of long-term burn outcomes.

Laser-Assisted Indocyanine Green Dye Angiography Accurately Predicts the Split-Thickness Graft Timing of Integra Artificial Dermis

The use of an artificial dermal substitute such as Integra-a bilaminate combination of thin silicone and cross-linked bovine tendon collagen and chondroitin-6-sulfate-has become a popular method to address large surface area wounds or smaller, complex wounds devoid of a vascular bed. The incorporation of Integra depends on a vascular wound bed or periphery and can take 4 weeks or longer to occur. If the Integra has not fully incorporated at the time of placement of the split-thickness graft, complete graft loss may result. The availability of a minimally invasive method to assess the incorporation of Integra would be of great value. Two 5 × 10-cm paraspinal full-thickness wounds were created on 3 female swine. Wounds were randomly assigned full-thickness skin graft or Integra (Plainsboro, NJ) treatment. Both types of grafts were placed after the application of fibrin glue (Tisseel, Deerfield, Ill) to the wound bed. Laser Doppler imaging (LDI) (Moor), indocyanine green dye (ICG) angiography (LifeCell SPY), and clinical scoring were performed weekly for a period of 8 weeks after grafting. At 4 weeks, the silicone layer of the Integra was removed, and a culture of autologous keratinocytes was applied. A 4-mm punch biopsy sample of each graft was taken 1, 2, 4, 6, 7, and 8 weeks postoperatively for histologic analysis. Both ICG angiography and LDI perfusion measurements noted an increase in perfusion at the Integra graft site that peaked 3 weeks after grafting, corresponding with the start of neovascularization and the optimal time for the application of a split-thickness skin graft. indocyanine green dye angiography measurements exhibit greater reproducibility between animals at late time points as compared with LDI. This decrease in LDI precision is directly related to increases in scar tissue thickness of greater than 5 mm as determined via histologic analysis and corresponds with the accepted maximum penetration depth of the LDI laser. Indocyanine green dye angiography may provide valuable information as to graft integrity and split-thickness skin graft timing at late time points. Range of LDI seems to be insufficient for split-thickness graft timing or late time point accuracy. Future exploration of ICG angiography potential will involve tracking Integra graft delay in porcine models.

Indocyanine green fluorescent dye during bowel surgery: Are the blood supply “guessing days” over?

Assessing the blood supply of the bowel is a difficult task even for experienced surgeons. Laser-assisted indocyanine green (ICG) fluorescent dye angiography provides intraoperative visual assessment of blood flow to the bowel wall and surrounding tissues, allowing for modification to the surgical plan, which can reduce the risk of postoperative complications. ICG angiography was prospectively performed in a single center during a 1-year period for small bowel ischemia and left colorectal resections. ICG angiography played a major role in the intraoperative decision making in 4 of 160 patients, whose clinical and operative details are here reported. In case of acute small intestine ischemia, resection is not warranted unless absolute perfusion units are below 19 (relative 21%). When evaluating blood supply to the left colon prior to anastomosing, resection is recommended with absolute units lower than 18 (relative 31%) even if the bowel appears macroscopically perfused.

Marginal Corneal Vascular Arcades

To determine the metrics of the marginal corneal vascular arcades (MCA). The MCA and filling pattern was investigated using indocyanine green dye angiography (ICGA) in the fellow eye of patients with treated unilateral keratitis. Images were acquired using a scanning laser ophthalmoscope. Five contiguous squares (100 pixels) were aligned beyond the inner row of vessels extending approximately 700 μm into the limbal region and spanning an arc length of approximately 4 mm of the peripheral cornea. Geometrical properties of the MCA were determined using programs written in a numerical computing environment. A total of 17 patients (24-88 years) were included. Filling of the inferior corneal quadrant occurred first, followed by superior, nasal, and temporal quadrants. Mean area of a vascular loop of the MCA was 11.87 × 10⁻³ mm² (SD: 10.44 × 10⁻³ mm²) skewed (2.20) toward smaller sizes. Mean circumference of a vascular loop was 422.5 μm (SD: 218.7 μm) with major and minor axes of 158.9 μm and 90.8 μm. There were five (SD: 1.8) branches per loop with a segment length of 89.5 um (SD 163.8 μm). Vessels were tortuous (mean 0.19, SD: 0.16) with a fractal number of 1.51 (0.12). There were significant differences between subjects in vessel loop area (P = 0.003) and number of branches (P = 0.002). Speed of flow was circumferential along the innermost row and measured at 0.22 mm/s in one subject. The MCA comprise a network of branched interlinked elliptical loops supporting circumferential blood flow in the corneal periphery. There was no definable change in vascular pattern extending into the limbal region.

Indocyanine green dye angiography accurately predicts survival in the zone of ischemia in a burn comb model

IntroductionSurgical evaluation of burn depth is performed via clinical observation, with only moderate reliability. While perfusion analysis has been proposed to enhance accuracy, no perfusion study has attempted to predict burn extension into the area of ischemia surrounding the original insult. We examined whether laser Doppler imaging (LDI) and indocyanine green (ICG) angiography predicted survival in the zone of ischemia in a porcine hot comb burn model. MethodologySix full-thickness wounds were created on 5 female Yorkshire swine using a validated porcine hot comb burn model. 4 full-thickness burns were created separated by 3 unburned interspaces that represent the zone of ischemia. The interspaces between each comb burn were monitored using LDI and ICG Angiography at 1, 4, 24, and 48h after burn. Interspace survival was assessed via gross observation and blinded histological readings 7 days after injury. ResultsICG Angiographic assessments of burn perfusion were significantly different in viable vs. non-viable interspace perfusion at 1h, 4h, and 48h. Temporal plotting of a trend-line derived from quantitative perfusion measurements rendered two distinct graphs, allowing for the derivation of a predictive algorithm to separate viable and non-viable interspaces. LDI revealed no such prognostic trend. ConclusionResults from a validated porcine burn comb model suggest that ICG angiography has significant potential in the prediction of burn progression early after burn. However, the full potential of this technology cannot be determined until completion of clinical trials.

Microsurgical treatment of ophthalmic segment aneurysms

Ophthalmic segment aneurysms refer to superior hypophyseal artery aneurysms, true ophthalmic artery aneurysms, and their dorsal variant. Indications for treatment of these aneurysms include concerning morphological features, large size, visual loss, or rupture. Although narrow-necked aneurysms are ideal endovascular targets, more complex and larger lesions necessitating adjunctive stent or flow-diversion techniques may be suitably treated with long-lasting, effective clip ligation instead. This is particularly relevant in the consideration of ruptured ophthalmic segment aneurysms. This article provides a depiction of microsurgical treatment of ophthalmic segment aneurysms with an accompanying video demonstration. Emphasis is placed on microsurgical anatomy, the intradural anterior clinoidectomy and clipping technique. The intradural anterior clinoidectomy, demonstrated in detail in our Supplementary video, provides significant added exposure of the ophthalmic segment of the internal carotid artery, allowing for improved aneurysm visualization. In the management of superior hypophyseal artery aneurysms, emphasis is placed on identifying and preserving superior hypophyseal artery perforators, using serial fenestrated straight clips rather than a single right-angled fenestrated clip to obliterate the aneurysm. Post-clipping indocyanine green dye angiography is a crucial tool to confirm aneurysm obliteration and the preservation of the parent vasculature and adjacent superior hypophyseal artery perforators. With careful attention to the nuances of microsurgical clipping of ophthalmic segment aneurysms, rewarding results can be obtained.

Intraoperative Perfusion Techniques Can Accurately Predict Mastectomy Skin Flap Necrosis in Breast Reconstruction

Intraoperative vascular imaging can assist assessment of mastectomy skin flap perfusion to predict areas of necrosis. No head-to-head study has compared modalities such as laser-assisted indocyanine green dye angiography and fluorescein dye angiography with clinical assessment. The authors conducted a prospective clinical trial of tissue expander-implant breast reconstruction with intraoperative evaluation of mastectomy skin flaps by clinical assessment, laser-assisted indocyanine green dye angiography, and fluorescein dye angiography. Intraoperatively predicted regions of necrosis were photographically documented, and clinical assessment guided excision. Postoperative necrosis was directly compared with each prediction. The primary outcome was all-inclusive skin necrosis. Fifty-one tissue expander-implant breast reconstructions (32 patients) were completed, with 21 cases of all-inclusive necrosis (41.2 percent). Laser-assisted indocyanine green dye angiography and fluorescein dye angiography correctly predicted necrosis in 19 of 21 of cases where clinical judgment had failed. Only six of 21 cases were full-thickness necrosis, and five of 21 required an intervention (9.8 percent). Risk factors such as smoking, obesity, and breast weight greater than 1000 g were statistically significant. Laser-assisted indocyanine green dye angiography and fluorescein dye angiography overpredicted areas of necrosis by 72 percent and 88 percent (p = 0.002). Quantitative analysis for laser-assisted indocyanine green dye angiography in necrotic regions showed absolute perfusion units less than 3.7, with 90 percent sensitivity and 100 percent specificity. Laser-assisted indocyanine green dye angiography is a better predictor of mastectomy skin flap necrosis than fluorescein dye angiography and clinical judgment. Both methods overpredict without quantitative analysis. Laser-assisted indocyanine green dye angiography is more specific and correlates better with the criterion standard diagnosis of necrosis. Diagnostic, I.

An Investigation of the Application of Laser-Assisted Indocyanine Green Fluorescent Dye Angiography in Pedicle Transverse Rectus Abdominus Myocutaneous Breast Reconstruction

Pedicle transverse rectus abdominus myocutaneous (pTRAM) flaps remain the most common method of autologous tissue breast reconstruction. Using pTRAM flaps, complications often arise postoperatively, secondary to inadequate circulation. Tissues from distant angiosomes are associated with poorer perfusion, but this differs among patients. Many modalities have been used to reduce the risk of complications, but none have achieved widespread application. The authors believe that laser-assisted indocyanine green fluorescent dye angiography (LA-ICGA) can potentially reduce the risk of complications. In two routine, single-pedicle, ipsilateral pTRAM flaps, LA-ICGA imaging was performed following the division of the distal rectus muscle and deep inferior epigastric pedicle. The resulting images were used to guide design of the flap and debridement. In case 1, good perfusion was observed in zone 1 and part of zone 2. In case 2, good perfusion was observed in zone 1 and 50% of zone 3, with little perfusion in zone 2. In both cases, tissues with poor perfusion were debrided before transfer and inset. In both patients, there were no issues with wound healing, tissue necrosis or fat necrosis. The variability of perfusion of the pTRAM flap among individuals is well appreciated. LA-ICGA helped to determine the limits of good perfusion and, therefore, the limits of tissue to be preserved for transfer and inset. This helped to avoid harvesting poorly perfused tissue that would have almost certainly experienced necrosis and, ultimately, would have reduced the risk of postoperative complications.

An investigation of the application of laser-assisted indocyanine green fluorescent dye angiography in pedicle transverse rectus abdominus myocutaneous breast reconstruction

An investigation of the application of laser-assisted indocyanine green fluorescent dye angiography in pedicle transverse rectus abdominus myocutaneous breast reconstruction

Retinal Angiomatous Proliferation Successfully Treated with Indocyanine Green Dye-Enhanced Photocoagulation.

This case series presents the use of indocyanine green dye-enhanced photocoagulation (ICG-DEP) for the treatment of retinal angiomatous proliferation (RAP). Five RAP lesions in 4 eyes of 3 patients were identified by fluorescein and indocyanine green dye angiography. The RAP lesions were treated with focal ablation of the intraretinal component using a ICG-DEP protocol. The 810-nm infrared laser in the pulsed millipulsed mode was used. The visual acuity and angiographic findings in the 3 patients with a follow-up from 18 months to 4 years are reported. The five RAP lesions were closed angiography in the 4 eyes of the 3 patients. All of the eyes had visual improvement for at least 8 months. In one stage 3 RAP lesion, there was visual improvement for 8 months until the choroidal neovascular membrane grew again. In this limited series, the procedure appeared to be safe and well tolerated with stable or improved visual acuity.

Early Experience with Fluorescent Angiography in Free-Tissue Transfer Reconstruction

Soft-tissue and bony reconstruction with free-tissue transfer is one of the most versatile tools available to the reconstructive surgeon. Determination of flap perfusion and early detection of vascular compromise with prompt correction remain critical in free-tissue transfer success. The aim of this report is to describe the utility of laser-assisted indocyanine green fluorescent dye angiography in free-tissue transfer reconstruction. From October of 2007 to March of 2008, 27 nonrandomized, nonconsecutive patients underwent surgical free flaps in conjunction with intraoperative Novadaq SPY fluorescent angiography. Twenty-seven patients underwent 29 free-tissue transfers. There was one partial flap loss in this group requiring operative revision. No complications attributable to indocyanine green fluorescent dye administration were noted. Imaging procedures (including dye administration) added minimal additional time to the operative time and anesthesia, and assisted in intraoperative decision-making. Novadaq's SPY fluorescent angiography system provides simple and efficient intraoperative real-time surface angiographic imaging. This technology places control of vascular anastomosis evaluation and flap perfusion in the hands of the surgeon intraoperatively in a visual manner that is easy to use and is helpful in surgical decision-making.

Simultaneous OCT/SLO/ICG Imaging

To evaluate how information from combined coronal optical coherence tomography (OCT) and confocal laser scanning ophthalmoscopy (SLO) with integrated simultaneous indocyanine green (ICG) dye angiography can be used in the diagnosis of a variety of macular diseases. A compact chin-rest-based OCT/confocal imaging system was used to produce the OCT image and excite the fluorescence in the ICG dye. The same eye fundus area can be visualized with coronal (C-scans, en face) OCT and ICG angiography simultaneously. Fast T scanning (transverse scanning, en face) was used to build B- or C-scan OCT images along with confocal SLO views, with and without ICG filtration. The OCT, confocal SLO and ICG fluorescence images were simultaneously presented in a three-screen format. A live mixing channel overlaid the ICG sequence on the coronal OCT slices in a fourth panel for immediate comparison. Thirty eyes were imaged. The pathologic conditions studied included classic and occult neovascular membranes, vascularized RPE detachments, polypoidal choroidal vasculopathy, traumatic choroidal rupture, diabetic maculopathy, central serous retinopathy, and macular drusen. Images were evaluated with special attention toward identifying novel relationships between morphology and function revealed by the superimposition of the studies. Simultaneous visualization of an en face (coronal, C-scan) OCT image and of an ICG angiogram, displayed side by side and superimposed, permits more precise correlations between late fluorescence accumulation with structures deep to the retinal surface at the retina-choroid interface. The multiplanar scanning also permits immediate B-scan OCT cross-sectional views of regions of abnormal fluorescence. The paper demonstrates the synergy between the two types of studies, functional and anatomic, in providing a more complete view of the pathologic condition.

Feasibility of Extracting Velocity Distribution in Choriocapillaris in Human Eyes from ICG Dye Angiograms

Indocyanine green (ICG) dye angiography has been used by ophthalmologists for routine examination of the choroidal vasculature in human eyes for more than 20 years. In this study, a new approach is developed to extract information from ICG dye angiograms about blood velocity distribution in the choriocapillaris and its feeding blood vessels. ICG dye fluorescence intensity rise and decay curves are constructed for each pixel location in each image of the choriocapillaris in an ICG angiogram. It is shown that at each instant of time the magnitude of the local instantaneous dye velocity in the choriocapillaris is proportional to both the slope of the ICG dye fluorescence intensity curve and the dye concentration. This approach leads to determination of the absolute value of blood velocity in the choriocapillaris, assuming an appropriate scaling, or conversion factor can be determined. It also enables comparison of velocities in different regions of the choriocapillaris, since the conversion factor is independent of the vessel location. The computer algorithm developed in this study can be used in clinical applications for diagnostic purposes and for assessment of the efficacy of laser therapy in human eyes.