Capsulorhexis Technique
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Brief Description
A capsulorhexis (or anterior capsulotomy), which uses the Greek suffix rhexis meaning “to tear”, is a surgical technique employed during cataract surgery to create a window in the anterior capsule wall of the lens of the eye and aids in the removal of the cataract. A well-executed capsulorhexis is critical for ensuring the postoperative stability of the intraocular lens (IOL).[1]
History of the Capsulorhexis Technique
Since the 18th century, the anterior capsulotomy has evolved from a gross tear in the capsule simply for extraction of the cataractous lens, into the technique we now recognize as continuous curvilinear capsulorhexis (CCC) making extraction of the lens possible with enough precision that the capsular bag is able to contain and stabilize the IOL. The development of the continuous circular capsulorhexis technique and laser technologies have provided major improvements to the centration of the lens, a necessary feature for premium lenses that rely on predictability of the lens position.
Prior to the mid 18th century, the removal of the cataractous lens was done by simply pushing the lens posteriorly towards the vitreous. In the mid-18th century, Jacques Daviel realized he could extract the nucleus from the lens by tearing it open with a cystotome. Minor advances continued until Cornelius Binkhorst realized that if you could fixate the IOL into the capsular bag it would become more stable and designed an IOL that was partly supported by the iris but mainly by the capsular bag. His biggest difficulty, however, was finding the best shape of the capsulotomy. Many tried varying techniques such as the “envelope”, “Christmas tree”, or “can opener” capsulotomy, all of which resulted in tearing at the edges and contraction of the capsule.
This led to the continuous curvilinear capsulorhexis first published by Howard Gimbel and Thomas Neuhann in 1990 which postulated that the continues curvilinear edge would reduce the chance of a capsular tear during surgery as it would stretch instead of tear in response to surgical forces. As such, it has become the standard method of anterior capsulotomy.[2] [3]
Principles of CCC Technique[4]
In general, the basic principles of the CCC technique are as follows:
- The continuous capsular tear should be performed in a stable anterior chamber under pressure by an ophthalmic viscosurgical device (OVD).
- The tear should be initiated at the center of the capsule, so the origin is included within the circle of the tear.
- The continuous tear should proceed either clockwise or counterclockwise, regrasping with the forceps or repositioning the point of the cystotome/bent needle on the inverted flap, controlling the vector of the tear.
- Leave the posterior capsule intact
Manual Capsulorhexis Technique[5]
Steps:
- Ensure the eye is filled with OVD to flatten the anterior capsule – there is less tendency for the capsular tear to move to the periphery if the surface is flattened out.
- Using either the cystotome or the tip of a capsulorhexis forceps, the anterior capsule is perforated near the center with the needle tip and then slitted in a curvilinear manner.
- When the desired circumference is reached, the capsule is lifted from underneath, close to the leading tear edge, and pushed upward and forward to propagate the tear.
- Engaging the flap
- If using the cystotome alone, engage the flap using the needle by exerting just enough pressure to create the friction for engagement with extreme care to not perforate.
- If using the forceps, grab the flap and propagate the tear.
- Once the capsular flap is engaged, it is torn in a circular fashion.
- The more distant the point of engagement from the leading edge, the more centripetally one must tear; the closer the point of engagement is to the leading edge, the more directly the tear will follow the direction of the traction.
- Therefore, it is importantly to frequently refixate the tear with the cystotome point frequently, close to the leading edge.
- When the tear is brought around full circle, the tear is blended into itself, automatically coming from outside in.
- The ideal capsulorhexis size dependent on the IOL optic size. The goal is to create a capsule opening of 5.0 to 5.2 mm for the optimal 6.0 mm diameter IOL overlap.
Special Considerations and Complications
Red Reflex Impairment[6]
The red reflex serves to aid in visualizing the round rim of the rhexis. The most common reasons for red reflex impairments are mature or white cataracts, opalescent cortical material, dense posterior subcapsular opacification, vitreous hemorrhage, or corneal clouding. In these circumstances, staining with a dye such as trypan blue enhances the visualization of the anterior capsule. The most common technique for staining involves injection of the trypan blue under an air bubble and subsequently washing the excess dye out. It has been noted, however, that the use of trypan blue can stiffen the anterior capsule and increase the risk of tears of the capsulorhexis.
Radial Extension[5][7]
As the capsulorhexis is performed, posterior pressure can cause the tear to extend radially towards the equator of the lens. If this occurs, the most important step is to resolve the posterior pressure by filling the anterior chamber with OVD. When promptly recognized, the flap can be redirected towards the center using the Little technique.
The Little technique requires the surgeon to grab the capsular flap and traction is applied in the same plane but opposite direction which redirects the flap centrally. If this fails to redirect the flap, it is suggested to either complete the capsulorhexis from the other direction or to cut the edge with intraocular scissors then complete the capsulorhexis.
If the tear extends towards the equator and it is not promptly captured, it could continue to radialize posteriorly leading to nucleus drop and vitreous loss.
Summary of Technique
Performing a Capsulorrhexis [8]
- Anterior capsulorrhexis is stained with Trypan Blue
- Use cystotome to scrape a tear in the anterior capsule
- Remove cystotome with side turn on retraction from incision
- Replace with capsulorrhexis microforceps and grasp one of the flaps and pull over briskly 180 degrees away from incision. Once flap is secured, stop and extend enough flap to fold over.
- Continue to grab flap about 1.5 mm away from the tear point, extending the tear in a continuous curvilinear fashion putting the torn capsule back in towards the center of the eye
- Continue shearing in a circular motion until completed with centered mass of capsule.
References
- ↑ Sharma, B., et al., Techniques of anterior capsulotomy in cataract surgery. Indian J Ophthalmol, 2019. 67(4): p. 450-460.
- ↑ Gimbel, H.V. and T. Neuhann, Development, advantages, and methods of the continuous circular capsulorhexis technique. J Cataract Refract Surg, 1990. 16(1): p. 31-7.
- ↑ Wygledowska-Promienska, D., et al., The evolution of the anterior capsulotomy. Wideochir Inne Tech Maloinwazyjne, 2019. 14(1): p. 12-18.
- ↑ Yanoff, M., et al., Ophthalmology. Sixth edition / ed. 2023, Philadelphia, PA: Elsevier. 1 online resource (1297 pages).
- ↑ 5.0 5.1 Garg, S., et al., Steinert's cataract surgery. Fourth edition. ed. 2023, Philadelphia, PA: Elsevier. 1 online resource.
- ↑ Mohammadpour, M., R. Erfanian, and N. Karimi, Capsulorhexis: Pearls and pitfalls. Saudi J Ophthalmol, 2012. 26(1): p. 33-40.
- ↑ Little, B.C., J.H. Smith, and M. Packer, Little capsulorhexis tear-out rescue. J Cataract Refract Surg, 2006. 32(9): p. 1420-2.
- ↑ MacDonald,S. Performing a Capsulorrhexis. YouTube https://youtu.be/xcdrX5zE0VY Accessed September 13, 2017.
