Optical coherence tomography-angiography for anterior uveal tract evaluation in normal subjects and in pathology

Purpose: to assess the potentials of optical coherence tomography-angiography (OCTA) in the evaluation of anterior segment (AS) uveal vessels in normal and pathological conditions.

Material and methods. 20 healthy volunteers (40 eyes) with no ophthalmic pathology (the control group) and 85 previously untreated patients (85 eyes) with suspected tumors of the irido-ciliary area (the iris, the ciliary body and the peripheral sections of the choroid) were examined. All participants had optical coherence tomography (OCT) and OCTA of AS, with the qualitative assessment of scans (vessels pattern, lumen, tortuosity) and the quantitative assessment (vessel density index, VD%, for the affected zone). In ciliary body or choroid pathologies, VD index was measured for the conjunctiva in the focus projection. VD index included mean and local VD, as well as VD of perifocal tissues. In addition, B-mode ultrasound scanning and ultrasound biomicroscopy were performed.

Results. OCTA scans in 4 sectors of the normal iris showed a predominantly radial pattern of conjunctival vessels positioning, with their lumen remaining the same along their entire visible length. The lowest VD value (38.5%) was registered in the temporal iris segment, while the highest (43.9%) was revealed in the inferior quadrant. In the iris tumors area, intrinsic vascularity molded in various vascular patterns was observed. Melanomas could be suspected because of the vessels oriented along the axis of the tumor and by non-uniform lumen of the vessels.

Conclusion. AS-OCTA is an informative method for the visualization of iris vessels in normal conditions and in iris pathology and may be considered a valuable addition to the standard visualization techniques.

1. Tulceva S.N., Titarenko A.I., Ruhovec A.G. The state of ocular circulation in young and middle—aged patients with retinal vein occlusion. Uchenye zapiski SPbGMU im. akad. I. P. Pavlova. 2017; XXIV (4): 29–34 (In Russ.).

2. Astahov Ju.S., Belehova S.G., Ruhovec A.G. On the correlation of morphological and functional parameters in the study of blood circulation of the eye. Regionalnoe krovoobrashhenie i mikrocirkuljacija. 2016; 15(4): 54–8 (In Russ.).

3. Kiseleva T.N., Kotelin V.I., Losanova O.A., Lugovkina K.V. Noninvasive methods assessment blood flow in anterior segment and clinical application perspective. Ophthalmology in Russia. 2017; 14 (4): 283–90 (In Russ.). doi: 10.18008/1816-5095-2017-4-283-290

4. Boginskaja O.A., Obrubov S.A. Diagnostic possibilities of studying the hemodynamics of the eye in myopia. Rossiyskaya detskaya oftalmologiya. 2014; (3): 27–32 (In Russ.).

5. Krivosheeva M.S., Ioyleva E.E. Optical coherence tomography — angiography as a non-invasive method of pathology diagnosis of the microcirculatory bed of the optic nerve and macula. Russian ophthalmological journal. 2021; 14 (2): 90–5 (In Russ.). doi: 10.21516/2072-0076-2021-14-2-90-95

6. Neroev V.V., Kiseleva T.N. eds. Ultrasound in ophthalmology: A guide for physicians. 1 ed. Мoscow: IKAR; 2019 (In Russ.).

7. Zakharova M.A., Kuroedov A.V. Optical coherence tomography: a technology that has become a reality. Klinicheskaya oftalmologiya. 2015; (4): 204–11 (In Russ.).

8. Konopi ska J, Lisowski , Wasiluk E, Mariak Z, Obuchowska I. The effectiveness of ultrasound biomicroscopic and anterior segment optical coherence tomography in the assessment of anterior segment tumors: Longterm follow-up. J Ophthalmol. 2020: 1–8. doi: 10.1155/2020/9053737

9. Skalet AH, Li Y, Lu CD, et al. Optical coherence tomography angiography characteristics of iris melanocytic tumors. Ophthalmology. 2017; 124 (2): 197–204. doi: 10.1016/j.ophtha.2016.10.003

10. Amiryan A.G., Saakyan S.V. Prognostic factors for uveal melanoma. Vestnik oftalmologii. 2015; 1: 90–5 (In Russ.). doi: 10.17116/oftalma2015131190-94

11. Akagi T, Uji A, Huang AS, et al. Conjunctival and intrascleral vasculatures assessed using anterior segment optical coherence tomography angiography in normal eyes. Am J Ophthalmol. 2018; 196: 1–9. doi: 10.1016/j.ajo.2018.08.009

12. Aicher NT, Nagahori K, Inoue M, Itoh Y, Hirakata A. Vascular density of the anterior segment of the eye determined by optical coherence tomography angiography and slit-lamp photography. Ophthalmic Res. 2020; 63 (6): 572–9. doi: 10.1159/000506953

13. Zett C, Stina DMR, Kato RT, Novais EA, Allemann N. Comparison of anterior segment optical coherence tomography angiography and fluorescein angiography for iris vasculature analysis. Graefes Arch Clin Exp Ophthalmol. 2018; 256 (4): 683–91. doi: 10.1007/s00417-018-3935-7

14. Williams BK Jr, Di Nicola M, Ferenczy S, Shields JA, Shields CL. Iris microhemangiomatosis: clinical, fluorescein angiography, and optical coherence tomography angiography features in 14 consecutive patients. Am J Ophthalmol. 2018; 196: 18–25. doi: 10.1016/j.ajo.2018.08.011

15. Lan G, Xu J, Hu Z, et al. Design of 1300 nm spectral domain optical coherence tomography angiography system for iris microvascular imaging. J Phys D: Appl. Phys. 2021; 54: 1–11. doi:10.1088/1361-6463/abf577

16. Brovkina A.F., ed. Ophthalmic oncology: A guide for physicians. Мoscow: Meditsina; 2002 (In Russ.).

17. Allegrini D, Montesano G, Pece A. Optical coherence tomography angiography of iris nevus: A case report. Case Rep Ophthalmol. 2016; 7 (3): 172–8. doi: 10.1159/000450572

18. Chien JL, Sioufi K, Ferenczy S, Say EAT, Shields CL. Optical coherence tomography angiography features of iris Racemose hemangioma in 4 Cases. JAMA Ophthalmol. 2017; 135 (10): 1106–10. doi: 10.1001/jamaophthalmol.2017.3390

19. Kang AS, Welch RJ, Sioufi K, et al. Optical coherence tomography angiography of iris microhemangiomatosis. Am J Ophthalmol Case Rep. 2017; 6: 24–6. doi: 10.1016/j.ajoc.2017.02.003

20. Mehta N, Liu K, Alibhai AY, et al. Impact of binarization thresholding and brightness/contrast adjustment methodology on optical coherence tomography angiography image quantification. Am J Ophthalmol. 2019; 205: 54–65. doi: 10.1016/j.ajo.2019.03.008

21. Hau SC, Papastefanou V, Shah S, et al. Evaluation of iris and iridociliary body lesions with anterior segment optical coherence tomography versus ultrasound B-scan. Br J Ophthalmol. 2015; 99 (1): 81–6. doi: 10.1136/bjophthalmol-2014-305218

22. Krema H, Santiago RA, Gonzalez JE, Pavlin CJ. Spectral—domain optical coherence tomography versus ultrasound biomicroscopy for imaging of nonpigmented iris tumors. Am J Ophthalmol. 2013; 156 (4): 806–12. doi: 10.1016/j.ajo.2013.05.025

23. Janssens K, Mertens M, Lauwers N, et al. To study and determine the role of anterior segment optical coherence tomography and ultrasound biomicroscopy in corneal and conjunctival tumors. J Ophthalmol. 2016; 2016: 1–11. doi: 10.1155/2016/1048760

24. Mackey DA, Wilkinson CH, Kearns LS, Hewitt AW. Classification of iris colour: review and refinement of a classification schema. Clin Exp Ophthalmol. 2011; 39 (5): 462–71. doi: 10.1111/j.1442-9071.2010.02487.x

25. Roberts PK, Goldstein DA, Fawzi AA. Anterior segment optical coherence tomography angiography for identification of iris vasculature and staging of iris neovascularization: A pilot study. Curr Eye Res. 2017; 42 (8): 1136–42. doi:10.1080/02713683.2017.1293113

26. Brouwer NJ, Marinkovic M, Bleeker JC, Luyten GPM, Jager MJ. Anterior segment OCTA of melanocytic lesions of the conjunctiva and iris. Am J Ophthalmol. 2021; 222: 137–47. doi: 10.1016/j.ajo.2020.09.009

27. Lee WD, Devarajan K, Chua J, et al. Optical coherence tomography angiography for the anterior segment. Eye Vis (Lond). 2019; 6: 4. doi: 10.1186/s40662-019-0129-2

28. Spaide RF, Fujimoto JG, Waheed NK. Optical coherence tomography angiography. Retina. 2015; 35 (11): 2161–2. doi: 10.1097/IAE.0000000000000881

29. Sampson DM, Dubis AM, Chen FK, Zawadzki RJ, Sampson DD. Towards standardizing retinal optical coherence tomography angiography: a review. Light Sci Appl. 2022; 11 (1): 63. doi: 10.1038/s41377-022-00740-9

30. Iovino C, Peiretti E, Braghiroli M, et al. Imaging of iris vasculature: current limitations and future perspective. Eye (Lond). 2022; 36 (5): 930–40. doi: 10.1038/s41433-021-01809-2

31. Nampei K, Oie Y, Kiritoshi S, et al. Comparison of ocular surface squamous neoplasia and pterygium using anterior segment optical coherence tomography angiography. Am J Ophthalmol Case Rep. 2020; 20. doi: 10.1016/j.ajoc.2020.100902