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Tripode IOL design prevents postop decentration
Three equally spaced haptics result in remarkable stability.
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Decentration can be a serious complication of posterior chamber IOL implantation. It results in glare and monocular diplopia when the IOL edge is not masked by a dilating pupil.
Proper foldable IOL centration is increasingly important. If the IOL haptics mechanically disrupt uveal tissue, the blood-aqueous barrier can break down, resulting in chronic uveitis, glaucoma and hyphema.
Vertical decentration can theoretically lead to a prismatic effect, which may induce a phoria. Factors causing decentration include asymmetrical fixation, radial anterior capsular tears and problems with haptic materials such as memory and rigidity.
Tripode
The Tripode (IOLTechnologie, La Rochelle, France) is a new design for the prevention of decentration of foldable IOLs. (Editor’s note: The Tripode IOL is not currently available in the United States.) The Tripode is a one-piece hydrophilic acrylic IOL with three full haptics 120° apart with no angulation. The lens has an optical zone of 6 mm and an overall length of 10.5 mm. This IOL, designed to reduce excessive stress on the capsular bag, may produce the most stable fixation.
| Follow-up time | |
| Time | Cases |
We implanted the Tripode IOL in 1,000 patients between March 1996 and October 1997. Follow-up on some of these patients is now 2 years. (See accompanying chart at right.) Surgery was performed under topical anesthesia with a small incision of 3.2 mm.
Estimated A-constant was 118.5. Lenses from +14 D through +27 D in 0.5 increments were used. The average age of patients was 61.3 ± 3.5 years. The average IOL power was 22.2 ± 3.8 D.
An incision of 3.2 mm was made and a continuous curvilinear capsulorrhexis was performed under viscoelastic. Routine endocapsular phacoemulsification was performed. Corneal or limbal incision enlargement of 3.5 mm to 4 mm was sometimes necessary to facilitate in-the-bag IOL insertion. A 3.5 mm incision was used for lenses of less than 22 D.
Of the 1,000 eyes in the study, in 942 the IOL was directly inserted in the bag (94.2%); in 58 (5.8%) the use of a spatula or hook was required to place one or two haptics without zonular trauma.
Measuring decentration
We routinely use a device called a capsulometer, which allows us to measure the capsulorrhexis size and centration or decentration of lenses. We use it during surgery to calibrate the size of the capsulorrhexis and to help achieve a circular one.
We also use the capsulometer postoperatively at the slit lamp biomicroscope to correlate IOL centration with symptoms. The capsulometer takes into account the corneal power. C-loop and J-loop IOLs show IOL decentrations higher than 0.5 mm in about 6% of eyes or more.
Patients receiving the Tripode were asked directly about symptoms likely to be caused by a decentered IOL: glare, halo and monocular diplopia. If significant posterior capsular opacification was noted, the symptoms were not attributed to decentration. Best corrected preoperative and postoperative Snellen visual acuities were recorded.
Results
In 1,000 eyes, best corrected visual acuity was 20/40 or better. Induced astigmatism was less than 1 D in all cases.
Twenty-five eyes received a capsular tension ring due to zonular trauma during surgery, to stabilize or strengthen a bag with weak zonules and for prevention of an asymmetrical retraction of the bag or retraction of the anterior capsulorrhexis.
No decentration was observed except one case of unintended sulcus implantation (0.1%). All 999 cases fixed in the capsular bag remained centered during short- and long-term examination. No glare or monocular diplopia was found in any case.
No displacement of more than 1 mm (pea-pod effect) was seen in 108 cases in which the rhexis edge touched the periphery of the optic.
Thirty-two eyes developed anterior capsule reaction, but they never developed capsular contraction syndrome. Because of the stress-free design of the IOL, distortion of the capsulorrhexis did not occur in any eye in our study. Postoperative stress folds in the posterior capsule, which often occur after implantation of IOLs with a large haptic diameter, were always transient.
The Tripode is a good lens to maintain centration of the optic. It is a lens to recommend for prevention of asymmetrical retraction of the bag or retraction of the anterior capsulorrhexis. It is an excellent design for the prevention of short- or long-term decentration of foldable IOLs.
 Three dimensional view of the Tripode lens showing the optic in the center of gravity of the whole lens. |  The Tripode is folded into a good position. |  A forceps holds the optic while the Livernois-MacDonald forceps folds the lens. The lens can also be injected. |
 The Livernois-MacDonald forceps fold the optic. |  Beyond the folded Tripode lies the empty bag. |  The folded Tripode is introduced into the bag full of viscoelastic product. The incision is 3.5 mm for diopters below 22 D and 3.8 mm for >22.5 D. A micromanipulator helps induce counterpressure. |
 The leading loop is introduced under the anterior capsule while the two trailing loops are placed upon the posterior capsule. The Livernois-MacDonald forceps is opened. There is no risk of posterior capsule rupture if the rhexis is intact. |  The Tripode lens is 10.5 mm in diameter with an optic of 6.5 mm. The three loops are 120º each. The material is hydrophilic and foldable. |  The Tripode folded with the leading loop unfolded. |
 No or low anterior capsular reaction with the hydrophilic acrylic material of the Tripode upon six month follow up. |  The Tripode is made of hydrophilic acrylic material. |  The Tripode is made of hydrophilic acrylic material. |
 Anterior capsular retraction in front of the optic (Sommering’s ring) with no displacement of the optic. This lens is not sensitive to the rhexis size, shape or centration. |  The optic is well centered while the rhexis is not centered. There is no displacement of the optic. |  Anterior capsular and posterior capsular adhesion remains clear out of the optic. The point where the anterior capsule comes in contact with the optic loops show no reaction with material, with no exaggerated whitening. |
 The capsulometer is a device that helps to measure the capsulorrhexis size and centering of the optic postoperatively. |  Although this monobloc PMMA lens is totally in the bag, we can see a displacement lens perpendicular to the great axis of the lens. Two loops are not enough to maintain short- and long-term centration of the optic. |
For Your Information:
- J. A. Hagege, MD, can be reached at 33 Rue de Ponthieu, 75008 Paris, France; (33) 1-56-88-18-00; fax: (33) 1-56-88-18-04. Dr. Hagege has a direct financial interest in the Tripode IOL. He is not a paid consultant for any companies mentioned in this article.
References:
- IOLTechnologie, manufacturer of the Tripode IOL, can be reached at Rue de la Désirée, 17000 La Rochelle, France; (33) 5-46-44-85-50; fax: (33) 5-46-44-85-60.
- De Groot V, Jonckheere P, Tassignon M-J. Centration of intraocular lens with circular haptics. J Cataract Refract Surg. 1997;23:1247-1253.
- Colvard EM, Dunn SA. Intraocular lens centration with continuous tear capsulotomy. J Cataract Refract Surg. 1990;16:312-314.
- Heider HW, Steinkamp GWK, Ohrloff C. Kapselsackfixierte PMMA-intraokularlinse. Ophthalmologie. 1993;90:325-328.