The 12th Congress of SIDUO took place in Iguazu Falls, Argentina, where participants could enjoy the scenery of the magnificent Falls. The organization was sponsored by the University Department of Oph­ thalmology, Buenos Aires; the University Department of Ophthalmology, EI Salvador; SAUMB (Socieded Argentina de Ultrasonografia en Medecina y Biologia) and CLEO (Club Latinoamericano de Ecografia OftalmoI6gica). The Honorary President was Professor Horacio Soriano from Buenos Aires. The local organizing committee consisted of the following persons: President Roberto Sampaolesi Vice President Atilio Lombardi Scientific Secretary: Eduardo Mayorga Treasurers Guillermo Iribarren Abelardo Cavatorta We are particularly grateful to Doctor J S Hillmann, Professor K C Ossoinig and Doctor nvf Thijssen, who have helped with their counsel and advice. I would also like to thank our congress secretaries Graciela Massonat and Cristina Taegl for their enormous help in organizing SIDUO XII. To Doctor Javier Cassiraghi and Doctor Walter de Gregory our thanks for their outstanding help in organizing the scientific sessions. Thanks are due to the commercial exhibitors and most of all to our sponsors: Laboratorios Pfoertner Cornealent and Biophysic Medical. Our special thanks to Doctor Tomas Pfoertner for his great administrative expertise and counsel and to Christine Warren from Biophysic for her help in financing these proceedings. The 12th SIDUO thanks for their generous support: Pupilent Plastic Lens Argentina, Grafica SA and Laboratorio Optico Santamarina.

One. The Orbit.- 1. Ultrasonically-guided biopsy in orbital tumours.- 2. Echodriven fine needle aspiration biopsy in orbital tumor diagnosis.- 3. Echography assisted fine needle aspiration biopsy for diagnosing orbital pseudotumor and lymphoma.- 4. Ultrasound diagnosis of orbital histiocytofibromas.- 5. Orbitary myxoma: ultrasonographic diagnosis.- 6. Pre-operative and post-operative echographic results on patients undergoing optic nerve sheath decompression.- 7. Evaluation of the subarachnoidal space-comparisons between ultrasound and high resolution NMR-techniques.- 8. Lesions of the lacrimal fossa: a retrospective echographic study.- 9. Ultrasound diagnosis of orbital schwannomas.- Two. Biometry.- 10. Automatic measurement technique of the axial length using a new type of B-mode ultrasonography.- 11. Transducer performance parameters and their influence on biometric results.- 12. Clinical usefulness of linking biometry systems to personal computers.- 13. Continuous biometry of the chrystalline lens during accommodation.- 14. Biometric investigation of the effect of gravity on the chrystalline lens during accommodation.- 15. In vivo determination of the speed of ultrasound in cataracted lenses.- 16. Biometry and characterization of the lens.- 17. Formulas and results of intraocular lens implantation.- 18. Axial length measurements and IOL power calculations in microphthalmic eyes.- 19. Ultrasound diagnosis of unilateral axial myopia.- 20. Biometry of retina choroid layer.- 21. Eye size of the premature infant around presumed term.- 22. Choroidal nevi: diagnosis with standardized echography.- 23. Echometry in congenital glaucoma: long-term results after 10 to 17 years of surgery.- 24. Long-term biooculometry of developmental glaucoma.- 25. Relation between axiallength and refraction in eyes with congenital glaucoma.- 26. Biometric study of eyes with angle closure glaucoma.- Three. Vitreoretinal Diseases.- 27. Correlation between echography, vitreous surgery findings and follow-up.- 28. Power spectrum analysis of ultrasonic radio-frequency signals in vitreous diseases.- 29. Vitreous membranes: update echographical diagnosis.- 30. Reliability of standardized ultrasound in pre-operative diagnosis for vitreous surgery in diabetic patients.- 31. Ultrasound imaging in retinopathy of prematurity: retinal detachment in ROP stage 5 eyes and eye as prognostic indicator.- 32. Gas retinal detachment treatment and echography.- 33. Echographically driven extraction of foreign bodies.- 34. A case with a macular granuloma seropositive for Toxocara canis examined with standardized echography.- Four. Intraocular Tumours.- 35. Ultrasonography in intraocular tumours.- 36. Morphological parameters of intraocular tumours taking part in echographical tracings.- 37. Tissue characterization by ultrasound.- 38. Retinoblastoma conservative treatment: ultrasonographic follow-up.- 39. Ultrasonographic findings in selected cases of masquerading syndrome.- 40. Choroidal melanomas - correlations between A- and B-scan ultrasonography, nuclear magnetic resonance imaging and histopathology.- 41. Doppler ultrasonography in the follow-up of malignant melanoma of the choroid.- 42. Possibilities and limitations of ultrasonographical localization of ruthenium-106-radioactive plaques during treatment.- 43. Tumour volume calculations by ultrasonographical data in the evaluation of regression patterns in ruthenium-treated melanomas.- 44. Echographic patterns simulating extrascleral extension of malignant melanoma following plaque removal.- 45. Intraoperative use ofultrasound to document proper plaque placement in treating choroidal melanoma.- 46. Acoustospectography and histology of intraocular Greene's melanoma.- Five. Other Ocular Pathology.- 47. A-mode combined with B-mode ultrasonic equipment (Ophthascan S) in ocular and orbital diagnosis.- 48. Echo-ophthalmography in children.- 49. Radio frequency echographical study of pseudophakodonesis.- 50. Uveal effusion and nanophthalmos.- 51. 'Monstrous' deformations (myopic staphyloma) detected by ultrasound.- 52. Echographic findings in malignant glaucoma.- 53. Ultrasound findings in brawny scleritis.- 54. Echographic findings in lymphoid hyperplasia of the choroid.- 55. Diffuse lymphoid infiltration Of the uvea and periocular tissues.- Six. Physics and Techniques.- 56. In vivo determination of sound velocity in eye media.- 57. Two and three dimensional image processings applied to ophthalmic region.- 58. Three dimensional scan using a single transducer and image construction.- 59. Three dimensional display of ocular region using an array transducer.- 60. The development and clinical application of the digital quantitative color scan- converter connected with the ophthalmic contact ultrasonographic apparatus.- 61. Analysis of fundus blood dynamics by the ultrasonic Doppler method in blocking therapy for the stellar ganglions of the cervical sympathetic nerve.- 62. Computerized analysis of echo signals: multicentric experience.- 63. RGB output: our experience.- Authors index.