Origin of the capsular tension ring

Origin of the capsular tension ring

LETTERS tion. Notwithstanding some of the methodology, most specifically the measurement of IOP on the operating table by tactile tension, the compos...

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LETTERS

tion. Notwithstanding some of the methodology, most specifically the measurement of IOP on the operating table by tactile tension, the composition of the authorship is somewhat surprising. One hundred twelve eyes were operated on by the same surgeon. The pressure measurements, which were made 30 minutes, 1 day, and 1 month after surgery, were presumably done by either technicians or the surgeon. One wonders why 2 optometrists are included in the list of authors. One interpretation of this could be that this represents pandering to optometric interests in an attempt to give credibility to their postoperative management of cataracts. The presence of optometric authors in the peer-reviewed cataract literature certainly could be used as ammunition in any debate on the merits of so-called comanagement. This is a relatively simple and straightforward study, and just what the 2 optometrists brought to the party could be questioned. RICHARD SCHULZE, MD Savannah, Georgia, USA Reference 1. Shingleton BJ, Wadhwani RA, O’Donoghue MW, et al. Evaluation of intraocular pressure in the immediate postoperative period after phacoemulsification. J Cataract Refract Surg 2001; 27:524 – 527

Reply: I am surprised and frankly quite disappointed in the letter by Richard Schulze, MD. He has taken speculation to an unreasonable level without knowing the facts of the situation in our practice. The optometrists who are included as authors in our paper are associates who work directly with me on a regular basis each day of the week. They happen to be experts in computers and also have strong statistical backgrounds because of their training; they help to coordinate our database management system that evaluates all surgery in cataract and glaucoma patients. As a result, they were actively involved in database management, data evaluation, and interpretation of results, as well as the statistical analysis for this paper. They are esteemed colleagues who support our continuing efforts to learn more about issues related to cataract and glaucoma surgery. I would encourage Dr. Schulze to establish the facts before he makes such “interpretations” in the future.—Bradford J. Shingleton, MD

Origin of the Capsular Tension Ring

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am writing to correct some misinformation that was published in this journal regarding the inventor of the capsular tension ring (CTR).1 1710

I believe that I was the first to design (in 1990), report at an academic meeting (in 1991), and publish a paper (in 1994) on the development of a poly(methyl methacrylate) open ring for use as a CTR. The original aim of my ring was to maintain the circular contour of the capsular bag and to prevent decentration and deformation of soft intraocular lenses (IOLs). Soon after I developed the ring, I found that it could also be used to reconstitute a round capsular bag in cases of zonular rupture. I initially developed the ring in 1990 with Pharmacia (now Pharmacia & Upjohn), and I hold the Japanese patent for the ring (patent no. 2129249, intraocular ring; registered on November 16, 1990). The original name for my ring was the capsular bag supporting ring, and I presented a video on its use in cadaver eyes at the film festivals of the American Society of Cataract and Refractive Surgery (ASCRS) and the European Society of Cataract & Refractive Surgeons (ESCRS) meetings in 1991. I also presented experimental studies using the ring at the film festivals of the 1991 ESCRS and 1992 ASCRS meetings. Both films, entitled “Lens Epithelial Expansion to the IOL Optics” and “Lens Epithelial Expansion Onto the Posterior Capsule,” respectively, received the grand prize. A scientific paper describing my experimental studies of the ring was published in JCRS in 1994.2 I also conducted extensive research regarding the use of the ring for zonular rupture in 1992 and presented my results at a video session of the 14th Congress of the Japanese Society of Ophthalmic Surgeons in February 1993. My capsular bag supporting ring and the subsequently reported and clinically used CTR are the same in principle. The only difference is that the latter has eyelets and the former does not. While I wanted to put my ring to clinical use, Pharmacia had no interest in pursuing this for commercial sale. The first presentation on the CTR made by Witschel and Legler was given at the ASCRS meeting in May 1993. They have not published scientific papers on the use of the ring. However, many papers by other authors have subsequently stated that the first report of the ring was the presentation by Witschel and Legler at the 1993 ASCRS meeting.1,3,4 This is clearly not correct, as my evidence shows. However, this misinformation has now spread worldwide and I respectfully request the assistance of JCRS in correcting this.

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LETTERS

A similar device, the equator ring,5 was independently designed by Hara at almost the same time I developed the capsular bag supporting ring. Although the 2 rings are made of different materials and therefore have different physical properties, they share the same purpose; that is, maintenance of the circular contour of the capsular bag. Specifically, the equator ring is a closed ring made of a soft material, while the capsular bag supporting ring is an open ring made of a rigid material. I strongly believe that Dr. Hara and I should receive appropriate acknowledgment as being the original inventors of the equator ring and the CTR, respectively. TOSHIYUKI NAGAMOTO, MD Tokyo, Japan References 1. Lang Y, Fineberg E, Garzozi HJ. Vitrectomy to remove a posteriorly dislocated endocapsular tension ring. J Cataract Refract Surg 2001; 27:474 – 476 2. Nagamoto T, Bissen-Miyajima H. A ring to support the capsular bag after continuous curvilinear capsulorhexis. J Cataract Refract Surg 1994; 20:417– 420 3. Cionni RJ, Osher RH. Endocapsular ring approach to the subluxated cataractous lens. J Cataract Refract Surg 1995; 21:245– 249 4. Cionni RJ, Osher RH. Management of profound zonular dialysis or weakness with a new endocapsular ring designed for scleral fixation. J Cataract Refract Surg 1998; 24:1299 –1306 5. Hara T, Hara T, Yamada Y. “Equator ring” for maintenance of the completely circular contour of the capsular bag equator after cataract removal. Ophthamic Surg 1991; 22:358 –359

Evaluation of Viscoelastic Substances

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n Holzer et al.’s article on the effect of viscoelastic substances on intraocular pressure (IOP) and the endothelium after cataract surgery,1 the authors conclude that Healon威5 (sodium hyaluronate 2.3%) was the most protective of endothelial cell loss. This conclusion, however, is misleading based on the methods used to derive the data. In this study, the surgeon was not masked and was required to remove all the ophthalmic viscosurgical devices (OVDs) at the end of surgery. The authors obviously knew that Viscoat威 (sodium hyaluronate 3.0%– chondroitin sulfate 4.0%) was a dispersive OVD that was retained on the endothelium throughout the surgery because they chose to measure the removal time of only the Viscoat and Healon5 groups. The article states that the observers and patients were masked as to the OVDs.

However, with 2 of the 5 groups having a special requirement (ie, timing of OVD removal), one has to question how the observers remained masked. The authors correctly state in the discussion that some endothelial cell loss with the dispersive OVDs may have been a result of the extended times needed for their complete removal. This is an important point that appears to have been forgotten when the overall conclusions were formulated. Obviously, the longer the surgeon has to remain in the anterior chamber, the more likely the unwanted effects. In addition, the more dispersive the OVD, the stronger the attraction to the endothelial cells; therefore, more effort is required to completely remove the dispersive OVD.2 With the protocol requiring complete removal of the OVD after surgery, the above 2 facts clearly bias the results against Viscoat. The Viscoat monograph states that Viscoat should be removed as completely as practical following surgery. Clinical studies have demonstrated that removing approximately 80% of Viscoat does not result in adverse IOP spikes. The approximately 20% of the Viscoat that remains in the anterior chamber is removed through the trabecular meshwork within 24 hours of surgery.3 The dispersive nature of Viscoat is a proven benefit for the surgeon during cataract surgery. The endothelial cell layer of the cornea is protected by the dispersive coating of this OVD. The protective benefits of Viscoat clearly outweigh any potential risks associated with incomplete removal following surgery, as has been proven in numerous clinical trials.2 When Viscoat is used as recommended by the manufacturer, this OVD is clearly a benefit for the surgeon. However, in the article by Holzer et al., the study design was skewed against a strong dispersive OVD and therefore the study conclusions are misleading. A fair comparison of OVDs should include the accepted method of use for each product evaluated. One must also consider the overall use of an OVD during surgery, and a risk/ benefit ratio should be applied to the entire surgical procedure and not to just one aspect of it. H. BURKHARD DICK, MD Mainz, Germany References 1. Holzer MP, Tetz MR, Auffarth GU, et al. Effect of Healon5 and 4 other viscoelastic substances on intraocular pressure and endo-

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