When performing cataract surgery and placing an intraocular lens, it is critical to achieve the optimal size and centration of continuous curvilinear capsulorhexis (CCC) to allow for a perfect 360-degree overlap with the IOL optic zone.1 To do this, CCC needs to be smaller than the optic zone of the IOL, with its center close to the center of the capsular bag.
While studies have shown that IOL centration is superior with femtosecond laser capsulotomies rather than manual CCCs,2-5 this can be difficult to accomplish. However, I have found that one tool has a feature that can aid in creating a perfect capsulotomy: it is the scanned capsule mode on the Catalys precision laser system (Johnson & Johnson Vision). In the 3.5 years that I have been using this laser, I’ve never had to remove an IOL — and that covers about 2,100 cases.
THE SCANNED CAPSULE MODE
Knowing and using the capabilities of the femtosecond cataract laser are the keys to success for capsulotomies.
Catalys’ scan capsule allows users to use OCT technology to analyze the volume, shape and center of the lens or cataract. Through the use of x- and y-axis sectional scanned images, this system creates safety margins when performing anterior and posterior lens capsule lens fragmentation.6 The laser system’s integrated algorithm provides the scanned capsule and estimates the coordinates of the angle center based on the location of the scanned capsule center.6 Combined with the predicted pupil center and limbal center provided by the system, surgeons can choose the center of the CCC before employing the laser.6
To this point, I have never had a lens without a perfect overlap, achieving a continuous capsule edge with an equal amount of overlap with the IOL.
USE WITH TORIC AND EDOF LENSES
I find this feature particularly useful with toric IOLs. With toric IOLs, one major goal is to prevent rotation. And while rotation is rare, it can happen with any style of toric lens. However, since I started using scan capsulotomy, I get a nice edge overlapping my optic that actually uses a slightly smaller capsulorhexis size, reducing the size from 5 mm to 4.8 mm.
This has dramatically reduced the instances of rotation.
The scanned capsular mode has also been very helpful when using extended-depth-of-focus (EDOF) or multifocal lenses when it is necessary for the lens to have a nice overlap. An EDOF lens should sit in the center of the optical axis. There are many theories about where the center of the optical axis is, along with strategies for best completing CCC7,8,9; nevertheless, it can be challenging to find the best location for the lens and ensure that it remains in place.
Theories about the importance of low-angle kappa and angle alpha values for EDOF or multifocal lenses continue to evolve. However, during cataract surgery, the only variables we can really control are the size, shape and centration of the capsulorhexis.
If the center of a patient’s pupil is close to the center of the visual optical axis — and that is in the center of the capsular bag — we can use the scan capsule mode to ensure that the lens is correctly centered and has the desired overlap.
Using the scan capsule mode also aids in avoiding optic tilt, which can induce coma and an astigmatic-like effect.10 Producing a 360-degree edge overlap on the optic ensures full capsule coverage.
POSSIBLE SIDE EFFECTS
I have not found that using this laser has caused many side effects. We could experience some slight subconjunctival hemorrhage associated with docking, but that is typically quite minimal. The only other possible side effects would be related to making arcuate cuts in the cornea. However, the same possibility exists when performing the procedure with a laser or doing manual arcuate incisions in the cornea.
The advantages I perceive in each step in using this laser provide me with the ultimate win: more patients who are happy and seeing clearly postoperatively. OM
- Smith SR, Daynes T, Hinckley M, Wallin TR, Olson RJ. The effect of lens edge design versus anterior capsule overlap on posterior capsule opacification. Am J Ophthalmol. 2004;138:521-526.
- Friedman NJ, Palanker DV, Schuele G, et al. Femtosecond laser capsulotomy. J Cataract Refract Surg. 2011;37:1189-1198.
- Nagy ZZ, Kránitz K, Takacs AI, et al. Comparison of intraocular lens decentration parameters after femtosecond and manual capsulotomies. J Cataract Refract Surg. 2011;27:564-569.
- Roberts TV, Lawless M, Bali SJ, Hodge C, Sutton G. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1500 consecutive cases. Ophthalmology. 2013;120:227-233.
- Mastropasqua L, Toto L, Mattei PA, et al. Optical coherence tomography and 3-dimensional confocal structured imaging system-guided femtosecond laser capsulotomy versus manual continuous curvilinear capsulorhexis. J Cataract Refract Surg. 2014;40:2035-2043.
- Lee YE, Joo CK. Assessment of lens center using optical coherence tomography, magnetic resonance imaging, and photographs of the anterior segment of the eye. Invest Ophthalmol Vis Sci. 2015;56:5512-5518. DOI:10.1167/iovs.15-17454.
- Wallace RB III. Capsulotomy diameter mark. J Cataract Refract Surg. 2003;29:1866-1868.
- Tassignon MJ, Rozema JJ, Gobin L. Ring-shaped caliper for better anterior capsulorhexis sizing and centration. J Cataract Refract Surg. 2006;32:1253-1255.
- Suzuki H, Shiwa T, Oharazawa H, Takahashi H. Usefulness of a semicircular capsulotomy marker. J Nippon Med Sch. 2012;79:195-197.
- Oshika T, Sugita G, Miyata K, et al. Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration. Br J Ophthalmol. 2007;91:185-188. doi:10.1136/bjo.2006.099945.