{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T09:56:56Z","timestamp":1790935016734,"version":"4.1.0"},"reference-count":20,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T00:00:00Z","timestamp":1790899200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>The intrinsic opacity of the sclera limits ab externo visualization of deeper structures such as Schlemm\u2019s canal, thereby constraining angle-based glaucoma surgery. Tartrazine, a US FDA-approved azo dye, transiently enhances tissue optical transparency and may improve intraoperative visualization. This study evaluated whether tartrazine improves the optical clarity of human corneoscleral rim segments (CSRS) and the ab externo visibility of Schlemm\u2019s canal cannulation. In this ex vivo feasibility (proof-of-concept) study, five human corneoscleral rims from donors unsuitable for corneal transplantation were obtained from Ramayamma International Eye Bank. Two rims were each divided into four quadrants (eight segments in total) and allocated to four groups (n = 2 independent segments per group): 0.25 or 0.50 M tartrazine, each without (CSRS-1) and with 6-0 Prolene suture cannulation of Schlemm\u2019s canal (CSRS-2), for 5 min. Segments were examined microscopically at 2.5\u00d7 magnification, and scleral transparency was compared before and after treatment. Scleral clarity and suture visibility were graded by four independent evaluators on a 0\u201310 scale, with 10 representing maximum clarity, giving eight scored observations per group from two independent segments. Three further rims (CSRS 5, 6, and 7) underwent histopathological evaluation, comparing tartrazine-treated rims (0.25 and 0.50 M) with untreated rims to assess tissue integrity. Tartrazine at both concentrations increased corneoscleral clarity from an untreated baseline (score 0), with mean clarity scores above 6 in all groups. In non-cannulated segments (CSRS-1), scores were 6.13 at both 0.25 and 0.50 M. In cannulated segments (CSRS-2), suture visibility improved to 6.63 at 0.25 M and 8.00 at 0.50 M, the latter significantly higher than the reference group (p = 0.008), although the difference between the two concentrations was not significant (interaction p = 0.168). Histopathology showed preserved histological structure with no gross structural damage on light microscopy at either concentration. In this small preliminary series, tartrazine rapidly enhanced scleral translucency and ab externo visualization of underlying structures, suggesting potential clinical utility in ophthalmic surgery pending in vivo validation. Larger studies with more independent specimens and objective optical measurements are required to confirm these findings.<\/jats:p>","DOI":"10.3390\/jcm15197633","type":"journal-article","created":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T09:10:48Z","timestamp":1790932248000},"page":"7633","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effect of Tartrazine Dye on Corneoscleral Rim Clarity: An Ab Externo Visualization of Cannulated Schlemm\u2019s Canal"],"prefix":"10.3390","volume":"15","author":[{"given":"Lakshminarayanan","family":"Gowtham","sequence":"first","affiliation":[{"name":"Dr. Chigurupati Nageshwara Rao Ocular Pharmacology Research Centre, LV Prasad Eye Institute, Hyderabad 500034, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sunita","family":"Chaurasia","sequence":"additional","affiliation":[{"name":"Cornea Services, Shantilal Shanghvi Cornea Institute, LV Prasad Eye Institute, Hyderabad 500034, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4152-6872","authenticated-orcid":false,"given":"Rashmi","family":"Krishnamurthy","sequence":"additional","affiliation":[{"name":"Glaucoma Services, LV Prasad Eye Institute, Hyderabad 500034, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gamal","family":"Mohamed","sequence":"additional","affiliation":[{"name":"King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Deepak P.","family":"Edward","sequence":"additional","affiliation":[{"name":"Research Department, King Khaled Eye Specialist Hospital and Research Center, Riyadh 11462, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Khaled K.","family":"Abu-Amero","sequence":"additional","affiliation":[{"name":"Research Department, King Khaled Eye Specialist Hospital and Research Center, Riyadh 11462, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,10,2]]},"reference":[{"key":"ref_1","unstructured":"Rowe, R.C., Sheskey, P.J., and Quinn, M.E. (2012). Handbook of Pharmaceutical Excipients, Pharmaceutical Press. [7th ed.]."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Ou, Z., Duh, Y.S., Rommelfanger, N.J., Keck, C.H.C., Jiang, S., Brinson, K., Zhao, S., Schmidt, E.L., Wu, X., and Yang, F. (2024). Achieving optical transparency in live animals with absorbing molecules. Science, 385.","DOI":"10.1126\/science.adm6869"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"609","DOI":"10.1016\/S0014-4835(03)00212-4","article-title":"Scleral structure, organisation and disease. A review","volume":"78","author":"Watson","year":"2004","journal-title":"Exp. Eye Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"R37","DOI":"10.1088\/0031-9155\/58\/11\/R37","article-title":"Optical properties of biological tissues: A review","volume":"58","author":"Jacques","year":"2013","journal-title":"Phys. Med. Biol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.preteyeres.2015.07.001","article-title":"Corneal structure and transparency","volume":"49","author":"Meek","year":"2015","journal-title":"Prog. Retin. Eye Res."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1016\/j.preteyeres.2014.08.002","article-title":"Biomechanics of Schlemm\u2019s canal endothelium and intraocular pressure reduction","volume":"44","author":"Stamer","year":"2015","journal-title":"Prog. Retin. Eye Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1111\/j.1442-9071.2010.02238.x","article-title":"Micropulse transscleral diode laser cyclophotocoagulation in the treatment of refractory glaucoma","volume":"38","author":"Tan","year":"2010","journal-title":"Clin. Exp. Ophthalmol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1479","DOI":"10.1021\/js9802594","article-title":"Permeability of cornea, sclera, and conjunctiva: A literature analysis for drug delivery to the eye","volume":"87","author":"Prausnitz","year":"1998","journal-title":"J. Pharm. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"526","DOI":"10.1016\/j.jtos.2020.04.009","article-title":"High resolution three-dimensional imaging of the ocular surface and intact eyeball using tissue clearing and light sheet microscopy","volume":"18","author":"Yang","year":"2020","journal-title":"Ocul. Surf."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Sun, T., Su, J., Zhao, Y., and Tie, X. (2026). Enhancing the efficiency of achieving optical transparency in live animals using absorbing molecules. J. Biomed. Opt., 31.","DOI":"10.1117\/1.JBO.31.5.054702"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1119","DOI":"10.1070\/QE2006v036n12ABEH013337","article-title":"Optical clearing of the eye sclera in vivo caused by glucose","volume":"36","author":"Genina","year":"2006","journal-title":"Quantum Electron."},{"key":"ref_12","unstructured":"Tuchin, V.V. (2015). Optical clearing of tissues and blood. J. Biomed. Opt., 20."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1016\/j.ophtha.2013.11.001","article-title":"Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy: Technique report and preliminary results","volume":"121","author":"Grover","year":"2014","journal-title":"Ophthalmology"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1016\/j.ajo.2017.06.004","article-title":"Randomized trial on illuminated-microcatheter circumferential trabeculotomy versus conventional trabeculotomy in congenital glaucoma","volume":"180","author":"Shakrawal","year":"2017","journal-title":"Am. J. Ophthalmol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"682","DOI":"10.1016\/j.jcrs.2010.10.055","article-title":"Canaloplasty: Three-year results of circumferential viscodilation and tensioning of Schlemm canal using a microcatheter to treat open-angle glaucoma","volume":"37","author":"Lewis","year":"2011","journal-title":"J. Cataract Refract. Surg."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Konopi\u0144ska, J., Mariak, Z., and R\u0119kas, M. (2020). Improvement of the safety profile of canaloplasty and phacocanaloplasty: A review of complications and their management. J. Ophthalmol., 2020.","DOI":"10.1155\/2020\/8352827"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Narawane, A., Trout, R., Viehland, C., Kuo, A.N., Vajzovic, L., Dhalla, A.H., and Toth, C.A. (2024). Optical clearing with tartrazine enables deep transscleral imaging with optical coherence tomography. J. Biomed. Opt., 29.","DOI":"10.1117\/1.JBO.29.S2.S20501"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"European Food Safety Authority (2009). Scientific Opinion on the re-evaluation of tartrazine (E 102). EFSA J., 7.","DOI":"10.2903\/j.efsa.2009.1331"},{"key":"ref_19","unstructured":"U.S. Food and Drug Administration (2023). Tartrazine (FD&C Yellow No. 5); 21 CFR \u00a774.705."},{"key":"ref_20","unstructured":"Food Safety and Standards Authority of India (2011). Food Safety and Standards (Food Products Standards and Food Additives) Regulations."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/19\/7633\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T09:21:00Z","timestamp":1790932860000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/19\/7633"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,10,2]]},"references-count":20,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["jcm15197633"],"URL":"https:\/\/doi.org\/10.3390\/jcm15197633","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,10,2]]}}}