Effectiveness of Kumar’s 2nd generation stainless steel spiral Schlemm’s canal expander in decreasing intraocular pressure in patients with primary open-angle glaucoma refractory to previous penetrating and non-penetrating glaucoma surgeries

PURPOSE: To evaluate effectiveness of Kumar's 2nd generation stainless steel spiral Schlemm's canal expander (SCE) in decreasing intraocular pressure (IOP) in patients with primary open-angle glaucoma (OAG) refractory to previous penetrating and non-penetrating glaucoma surgeries. METHODS: Nine consecutive patients (9 eyes) having failed filters (failed trabeculectomy - 6 cases, failed deep sclerectomy - 2 cases and failed selective laser trabeculoplasty - 1 case), who's IOP was insufficiently controlled, were operated upon. A 2.5-3.0 mm long stainless steel spiral 2nd generation SCE made from 0.04mm thick medical grade stainless steel wire, having outer diameter of 0.2 mm and inner lumen diameter of 0.12 mm was implanted into Schlemm's canal (SC) ab externo. Two patients (2 eyes) with coexisting cataract and glaucoma underwent a combined procedure. Patients were evaluated daily during hospital stay, after 1 week, and at 1, 3, 6 and 12 months after surgery. IOP was considered a primary outcome measure. Secondary outcome measures were as follows: the number of glaucoma medications pre- and postoperatively and complications. A paired t-test was used for IOP and medication analysis. Decrease in IOP >20% or IOP from 6 to 18 mmHg without medication was considered a complete success, with medication - partial success. Failure was declared if the patient had IOP < 6 mmHg or > 18 or reduction in IOP was <20% after 3 months and if patient needed a subsequent filtering surgery. Success rates were evaluated at each follow-up visit after 3 months after surgery. Statistical analysis was performed using MS office application - Excel 2007 at each follow-up visit taking into account the change in the number of patients. Results were considered significant with p<0.05. RESULTS: Mean (mean+standard deviation (SD)) preoperative IOP was 25.2+5.5 mmHg. At each follow-up a decrease in mean IOP was observed, resulting in 12.5+3.9 mmHg (p=.00003) at 6 months and 12.9+1.4 mmHg (p=.00009) at 12 months. This represents a reduction in IOP from baseline of 49.4+17.4 and 44.2+9.8% at 6 and 12 months respectively. Mean number of used medications decreased from baseline 2.4+1.0 to 1.4+1.0 (p=0.05) and 1.0+1.0 (p=0.03) at 6 and 12 months respectively. Complete and partial success were observed in 2 and 6 cases (n=9) at 3 months, in 2 and 7 cases (n=9) at 6 months and 2 and 3 cases (n=5) at 12 months. There was only 1 case at 3 months, who fulfilled the failure criteria. There were no failure cases at 6 and 12 months. Intraoperative microperforation of trabecular meshwork (TM) in areas other than exposed part of SC occurred in 1 case. In 7 cases the device could be inserted completely into SC lumen. In 2 cases the caudal end (0.5 mm) of the device was left in the exposed part of SC. In the early post-operative period a bleb was noticed in 3 cases at 1 week and in 1 case at 1 and 3 months each. Complications like device dislocation, inflammation at the implantation site, devices' erosion through TM, loss of device were nil. YAG laser trabeculopucture was not required in any of the cases. CONCLUSION: Kumar's 2nd generation SCE is effective in decreasing IOP in patients with primary OAG refractory to previous penetrating and non-penetrating glaucoma surgeries. Use of medications is significantly reduced after implantation of this device.

Schlemm's canal surgery, Schlemm's canal expander, glaucoma surgery, refractory glaucoma surgery, хирургия шлеммова канала, экспандер шлеммова канала, хирургия глаукомы, хирургия рефрактерной глаукомы

1. Quigley H.A., Broman A.T. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006; 90(3): 262-267. doi: 10.1136/bjo.2005.081224.

2. Gedde S.J., Herndon L.W., Brandt J.D., Budenz D.L., Feuer W.J., Schiffman J.C. Surgical complications in the tube versus trabeculectomy study during the first year of follow-up. Am J Ophthalmol 2007; 143(1): 23-31. doi: 10.1016/j.ajo.2006.07.022.

3. Scott I.U., Greenfield D.S., Schiffman J., Nicolela M.T., Rueda J.C., Tsai J.C., Palmberg P.F. Outcomes of primary trabeculectomy with the use of adjunctive mitomycin. Arch Ophthalmol 1998; 116(3): 286-291.

4. Edmunds B., Thompson J.R., Salmon J.F., Wormald R.P. The National Survey of Trabeculectomy. III. Early and late complications. Eye 2002; 16(3): 297-303.

5. Jampel H.D., Musch D.C., Gillespie B.W., Lichter P.R., Wright M.M., Guire K.E. Collaborative Initial Glaucoma Treatment Study Group. Perioperative complications of trabeculectomy in the the collaborative initial glaucoma treatment study (CIGTS). Am J Ophthalmol 2005; 140(1): 16-22. doi: 10.1016/j.ajo.2005.02.013.

6. Fontana H., Nouri-Mahdavi K., Lumba J., Ralli M., Caprioli J. Trabeculectomy with mitomycin C: outcomes and risk factors for failure in phakic open-angle glaucoma. Ophthalmology 2006; 113(6): 930-936. doi: 10.1016/j.ophtha.2006.01.062.

7. Gedde S.J., Herndon L.W., Brandt J.D., Budenz D.L., Feuer W.J., Schiffman J.C. Tube Versus Trabeculectomy Study Group. Postoperative Complications in the Tube Versus Trabeculectomy (TVT) Study during five years of follow-up. Am J Ophthalmol 2012; 153(5): 804-814. doi: 10.1016/j.ajo.2011.10.024.

8. Saheb H., Ahmed K. II. Micro-invasive glaucoma surgery: current perspectives and future directions. Curr Opin Ophthalmol 2012; 23(2): 96-104. doi: 10.1097/ICU.0b013e32834ff1e7.

9. MIGS: advances in glaucoma surgery / edited by Kahook M.Y.; associate editors: Sarwat S., Leonard K. Seibold. USA. SLACK Incorporated 2014. 122 p.

10. Grant W.M. Experimental aqueous perfusion in enucleated human eyes. Arch Ophthalmol 1963; 69(6): 738-801.

11. Johnson D.H., Johnson M. How does nonpenetrating glaucoma surgery work? Aqueous outflow pathway morphology. Invest Ophthalmol Vis Sci 1999; 40(8): 1676-1680.

12. Nesterov A.P. Role of the blockade of Schlemm’s canal in pathogenesis of primary open-angle glaucoma. Am J Ophthalmol 1970; 70(5): 691-696.

13. Нестеров А.П. Глаукома. М.: 1995; 33-46, 103-130. [Nesterov A.P. Glaukoma [Glaucoma]. Moscow, 1995; 33-46, 103-130. (in Russ.)].

14. Zhou J., Smedley G.T. A trabecular bypass flow hypothesis. J Glaucoma 2005; 14(1): 74-83.

15. Zhou J., Smedley G.T. Trabecular bypass; effect of Schlemm canal and collector channel dilation. J Glaucoma 2006; 15(5): 446-455.

16. Samuelson T.W., Katz L.J., Wells J.M., Duh Y.J., Giampor-caro J.E. US iStent Study Group. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology 2011; 118(3): 459-467. doi: 10.1016/j.ophtha.2010.07.007.

17. Arriola-Villalobos P., Martinez-de-la-Casa J.M., Diaz-Valle D., García-Vidal S.E., Fernández-Pérez C., García-Sánchez J., García-Feijoó J. Mid-term evaluation of the new Glaukos iStent with phacoemulsification in coexistent open-angle glaucoma or ocular hypertension and cataract. Br J Ophthalmol 2013; 97(10): 1250-1255. doi: 10.1136/bjophthalmol-2012-302394.

18. Samuelson T., Tetz M., Pfeiffer N., Ramirez M., Scharioth G., Vass C. One year results of a nickel-titanium Schlemm’s canal microstent for IOP reduction after cataract surgery in open angle glaucoma. Paper presented at: 117th annual meeting of American Academy of Ophthalmology. November, 2012; Chicago, Il.

19. Camras L.J., Yuan F., Fan S., Samuelson T.W., Ahmed I.K., Schieber A.T., Toris C.B. A novel Schlemm’s canal scaffold increases outflow facility in a human anterior segment perfusion model. Invest Ophthalmol Vis Sci 2012; 53(10): 6115-6121. doi: 10.1167/iovs.12-9570.

20. Francis B.A., Minckler D., Dustin L., Kawji S., Yeh J., Sit A., Mosaed S., Johnstone M. Trabectome Study Group. Combined cataract extraction and trabeculotomy by the internal approach for coexisting cataract and open-angle glaucoma: initial results. J Cataract Refract Surg 2008; 34(7): 1096-1103. doi: 10.1016/j.jcrs.2008.03.032.

21. Иванов Д.И., Никулин М.Е., Струков В.В. Способ одномоментного хирургического лечения катаракты и глаукомы путем трабекулотомии ab interno и инструмент для ее выполнения. Патент РФ на изобретение № 2389456. Опубликовано 20.05.2010. Бюлл. 14

22. Иванов Д.И. Трабекулотом ирригационный. Патент РФ на полезную модель № 109662. Опубликовано 27.10.2011. Бюлл. 30

23. Shingleton B., Tetz M., Korber N. Circumferential viscodilation and tensioning of Schlemm canal (canaloplasty) with temporal clear corneal phacoemulsification cataract surgery for open-angle glaucoma and visually significant cataract: one-year results. J Cataract Refract Surg 2008; 34(3): 433-440. doi: 10.1016/j.jcrs.2007.11.029.

24. Ayyala R.S., Chaudhry A.L., Okogbaa C.B. et al. Comparison of surgical outcomes between canaloplasty and trabeculectomy at 12 months’ follow-up. Ophthalmology 2011; 118(12): 2427-2433. doi: 10.1016/j.ophtha. 2011.05.021.

25. Grieshaber M.C., Pienaar A., Olivier J., Stegmann R. Canaloplasty for primary open-angle glaucoma: long-term outcome. Br J Ophthalmol 2010; 94(11): 1478-1482. doi: 10.1136/bjo.2009.163170.

26. Grieshaber M.C., Fraenkl S., Schoetzau A., Flammer J., Orgül S. Circumferential viscocanalostomy and suture canal distension (canaloplasty) for Whites with open-angle glaucoma. J Glaucoma 2011; 20(5): 298-302. doi: 10.1097/IJG.0b013e3181e3d46e.

27. Johnstone M., Curtis K., Passin D. et al. New imaging techniques to study transparent tobules (TT) spanning Schlemm’s canal structures subject to disruption by SC surgery. AGS 21st annual meeting 2011, poster abstracts, poster N 32.

28. Кумар В., Фролов М.А., Душина Г.Н., Божок Е.В., Беззаботнов А.И. Сегментарная дилятация шлеммова канала с помощью стального спирального стента собственной конструкции в хирургии открытоугольной глаукомы. Медицинский вестник Башкортостана 2014; 2: 58-62

29. Kumar V., Frolov M.A., Bozhok E.V., Dushina G.N., Bezzabotnov A.I. A new stainless steel spiral Schlemm’s canal expander in surgical treatment open-angle glaucoma. Национальный журнал глаукома 2014; 3: 43-51

30. Sampaolesi R., Argento C. Scanning electron microscopy of the trabecular meshwork in normal and glaucomatous eye. Invest Ophthalmol Vis Sci 1977; 16(4): 302-314.

31. Ramos R.F., Hoying J.B., Witte M.H., Daniel Stamer W. Schlemm’s canal: endothelia, lymphatic, or blood vasculature? J Glaucoma 2007; 16(4): 391-405.

32. Irshad F.A., Mayfield M.S., Zurakowski D., Ayyala R.S. Variation in Schlemm’s canal diameter and location by ultrasound biomicroscopy. Ophthalmology 2010; 117(5): 916-920. doi: 10.1016/j.ophtha.2009.09.041.

33. Hong J., Xu J., Wei A., Wen W., Chen J.,Yu X., Sun X. Spectral-Domain Optical Coherence tomographic assessment of Schlemm’s canal in chinese subjects with primary open-angle glaucoma. Ophthalmology 2013; 120(4): 709-715. doi: 10.1016/j.ophtha.2012.10.008.

34. Кумар В., Фролов М.А., Душина Г.Н., Божок Е.В., Беззабот-нов А.И. Результаты снижения внутриглазного давления у пациентов с открытоугольной глаукомой при сегментарном расширении шлеммова канала с помощью интраканального экспандера второго поколения собственной конструкции. Альманах клинической медицины 2015; 36: 29-33

35. Краснов М.М. Микрохирургия глауком. М.: 1980; 235-236. [Krasnov M.M. Mikrokhirurgiya glaukom [Microsurgery of glaucoma]. Moscow, 1980; 235-236. (In Russ.)].

36. Ramulu P.Y., Corcoran K.J., Corcoran S.L., Robin A.L. Utilization of various glaucoma surgeries and procedures in Medicare beneficiaries from 1995 to 2004. Ophthalmology 2007; 114(12): 2265-2270. doi: 10.1016/j.ophtha.2007.02.005.

37. Fontana H., Nouri-Mahdavi K., Caprioli J. Trabeculectomy with mitomycin C in pseudophakic patients with open-angle glaucoma: outcomes and risk factors for failure. Am J Ophthalmol 2006; 41(4): 652-659. doi: 10.1016/j.ajo.2005.11.039.

38. Saheb H., Gedde S.J., Schiffman J.C., Feuer W.J. Outcomes of glaucoma reoperations in the Tube versus Trabeculectomy (TVT) study. Am J Ophthalmol 2014; 157(6): 1179-1189. doi: 10.1016/j.ajo.2014.02.027.

39. Ainsworth J.R., Lee W.R. Effects of age and rapid high-pressure fixation on the morphology of Schlemm’s canal. Invest Ophthalmol Vis Sci 1990; 31(4): 745-750.

40. Allingham R.R., de Kater A.W, Ethier C.R. Schlemm’s canal and primary open angle glaucoma: correlation between Schlemm’s canal dimensions and outflow facility. Exp Eye Res 1996; 62(1): 101-109.

41. Johnson D.H., Matsumoto Y. Schlemm’s canal becomes smaller after successful filtration surgery. Arch Ophthalmol 2000; 118(9): 1251-1256.

42. Lütjen-Drecoll E. Functional morphology of the trabecular meshwork in primate eyes. Prog Retin Eye Res 1999; 18(1): 91-119. PMID: 9920500.

43. Fea A.M., Dogliani M, Machetta F., Lale-Lacroix G., Brogliatti B., Grignolo F.M. The trabecular bypass stent in a pseudophakic glaucoma patient: a 1 year follow-up. Clin Ophthalmol 2008; 2(4): 931-934. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699816/pdf/co-2-931.pdf. Accessed February 1, 2015.

44. Roelofs K., Arora S., Dorey M. W. Implantation of 2 trabecular microbypass stents in a patient with primary open-angle glaucoma refractory to previous glaucoma-filtering surgeries. J Cataract Refract Surg 2014; 40(8): 1322-1324. doi: 10.1016/j.jcrs.2014.06.017.

45. Bussel I.I., Kaplowitz K., Schuman J.S., Loewen N.A. Outcomes of ab interno trabeculectomy with the trabectome after failed trabeculectomy Trabectome Study Group. Br J Ophthalmol 2015; 99(2): 258-262. doi: 10.1136/bjophthalmol-2013-304717.

46. Teberg-Harms M.T.O., Rhee D.J. Selective laser trabeculoplasty following failed combined phacoemulsification cataract extraction and ab interno trabeculectomy. Am J Ophthalmol 2013; 156(5): 936-940. doi: 10.1016/j.ajo.2013.05.044.

47. Brusini P., Tosoni C. Canaloplasty after failed trabeculectomy: a possible option. J Glaucoma 2014; 23(1): 33-34. doi: 10.1097/IJG.0000000000000188.

48. Stamer W.D., Acott T.S. Current understanding of conventional outflow dysfunction in glaucoma. Curr Opin Ophthalmol 2012; 23(2): 135-143. doi: 10.1097/ICU.0b013e32834ff23e.

49. Smit B.A., Johnstone M.A. Effects of viscoelastic injection into schlemm’s canal in primate and human eyes. Potential relevance to viscocanalostomy. Ophthalmology 2002; 109(4): 786-792.