AIM: To evaluate the diagnostic value of panoramic immersion B-scan ultrasonography (Pano-immersion B-scan, PIB) in complex retinal detachment (RD), persistent hyperplastic primary vitreous (PHPV) and intraocular tumors. METHODS: The clinical data of 44 patients collected from May 2012 to December 2019 in Chinese PLA General Hospital was retrospectively studied. All of these patients underwent PIB of the eye, because it was difficult to diagnose by routine ocular fundus examination, conventional ultrasound or/and ultrasonic biomicroscope (UBM) due to opacity of refractive media, pupillary occlusion, large involvement or special location of the lesion. The imaging features of difficult cases in PIB were analyzed. The diagnosis accuracy rating of PIB were evaluated and contrasted with conventional ultrasound or UBM by the standard of intraoperative diagnosis or/and pathological results. RESULTS: According to intraoperative diagnosis or pathological results as gold standard, among the 44 cases, there were 19 cases missed diagnosis, misdiagnosed or difficult-to-diagnose by conventional ultrasound or UBM, including 4 cases of long-standing RD difficult to diagnose, 4 cases misdiagnosed, and 11 cases incompletely observed or miss diagnosed. The diagnostic accuracy rate of PIB and conventional ultrasound or UBM were 100% (44/44) and 56.82% (25/44), and the sensitivity of them were 100% and 56.82%. All the patients underwent PIB and were diagnosed as RD (15 cases), retinal and choroidal detachment (4 cases), subchoroidal hematocele (1 case), vitreous opacity and/or organic membrane formation (4 cases), PHPV (12 cases), iris and/or ciliary body tumors (3 cases), and choroidal tumors (6 cases). According to the intraoperative diagnosis or pathological results, the diagnostic coincidence rate of PIB was 100%, which was significantly higher than conventional ultrasound and UBM. CONCLUSION: PIB can help to accurately diagnose complex RD, PHPV, and intraocular masses with special location or/and excessive size. It has important diagnostic value for patients with equivocal findings at conventional ultrasound examination.