Endomicroscopy (EM) can improve the diagnosis Barrett's esophagus (BE) and some early esophageal cancers (Intra Epithelial Neoplasia (IEN)). EM provides optical biopsies comparable to standard histology. Specifically, EM allows targeted biopsy rather than random mucosal biopsy during routine endoscopic surveillance of BE or evaluation EIN, which will improve the diagnostic yield of mucosal samples for BE IEN. Furthermore, when combined with high resolution endoscopy, EM may improve the overall in vivo detection of IEN in lesions as well as flat mucosa.

EM will provide accurate place and size of IEN which will impact the physician's decision to biopsy or perform endoscopic mucosal resection (EMR). This could potentially minimize the number of unnecessary biopsies and as well as enable the physician to perform EMR at the time of the initial examination, rather than delaying endoscopic treatment after the pathology is available. This study is important because it will validate single center studies supporting the routine use of EM for screening and surveillance of BE.

The central hypothesis is that endomicroscopy (EM) can improve the efficiency of the endoscopic diagnosis of Barrett's esophagus (BE) and associated Intraepithelial neoplasia(IEN), providing in-vivo optical biopsies comparable to standard histology. Specifically, EM will enable targeted biopsy rather than random mucosal biopsy during routine endoscopic surveillance of BE or endoscopic evaluation of patients with suspected or proven unlocalized IEN, which will improve the diagnostic yield of mucosal samples for BE IEN. Furthermore, when combined with high resolution endoscopy, EM may improve the overall in vivo detection of IEN in lesions as well as flat mucosa.

The investigators also hypothesize that EM will provide additional accurate information regarding the presence of IEN that will impact upon the physician's decision to obtain a mucosal biopsy or perform endoscopic mucosal resection (EMR). This could potentially minimize the number of unnecessary biopsies and as well as enable the physician to perform EMR at the time of the initial examination, rather than delaying endoscopic treatment to another procedure after the pathology from the mucosal biopsies are available. This study is important because it will validate single center studies supporting the routine use of EM for screening and surveillance of BE.

Inclusion Criteria:

• Surveillance of Barrett's esophagus or suspected or known BE associated neoplasia

Exclusion Criteria:

• Allergy or prior reaction to the fluorescent contrast agent fluorescein sodium
• Unable to give informed consent.
• Pregnant or breastfeeding women
• Known advanced adenocarcinoma in the esophagus
• Dysplastic or suspected malignant esophageal lesion 0 BE lesions 2 cm or more in size with Paris classification of 0-Ip (polypoid), 0-Is (protruding sessile), 0-IIa (flat elevated), or 0-IIb (flat)
• Lesions of any size with Paris 0-IIc (superficial shallow depressed) or 0-III (excavated)
• Acute gastrointestinal bleeding
• Coagulopathy defined by Partial Thromboplastin Time (PTT) > 50 sec, or International Normalized Ratio (INR) > 2.0, platelets < 40,000, or on chronic anticoagulation
• Inability to tolerate sedated upper endoscopy due to cardio-pulmonary instability or other contraindication to endoscopy.
• History of a severe allergic reaction (anaphylaxis)
• Known, untreated esophageal strictures, prior partial esophageal resection, or altered anatomy preventing passage of the endomicroscope