Robert M. Kershner, MD, FACS
Vol. 20, No. 7, August 2002
R.M. Kershner — Director of Cataract and Refractive Surgery, Eye Laser Center, Tucson, Arizona; Clinical Professor of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah; Ik Ho Visiting Professor of Ophthalmology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
Correspondence to: Dr. Robert M. Kershner, Eye Laser Center, Suite 303, 1925 West Orange Grove Road, Tucson, Arizona USA 85704-1152; E-mail: Kershner@EyeLaserCenter.com; Web site:
Dr. Kershner has no financial or proprietary interest in any of the techniques or instruments described in this article. This article received the "Best Paper of Session" award at the 2001 American Society of Cataract and Refractive Surgery Symposium held in San Diego, California.
The growing popularity of refractive surgical procedures that eliminate or reduce the need for eyeglasses has led to the use of small (less than 2.5 mm) incisions, which, along with the insertion of an intraocular lens allows for correction of preexisting myopia, hyperopia and astigmatism during cataract surgery.
Procedure: This paper describes a clear corneal cataract surgery technique using a single-incision, single-instrument approach. This technique consists of using the smallest possible clear corneal microincision, and involves simultaneous correction of spherical and astigmatic errors with refractive keratotomy and toric intraocular lenses. In-the-bag phacoemulsification is performed and the intraocular lens is injected through the unenlarged microincision.
Results: Microincision cataract surgery has all but eliminated the complications of wound leak, uveal prolapse, and surgically-induced astigmatism, and has optimized the refractive results for the patient while providing immediate recovery without restrictions in normal postoperative activities. The refractive outcomes of these techniques, as performed in our Eye Laser Center in Tucson, Arizona, are the best we have ever achieved.
Lens extraction with implantation of an intraocular lens (IOL) is the most common refractive procedure in the world today. Since the invention of the IOL by the late Mr. Harold Ridley, in England in 1949, lens implantation has been the primary means to correction of the most common refractive error, aphakia, which occurs as a result of cataract extraction. In 1994, I published results of clear corneal cataract surgery with simultaneous correction of myopia, hyperopia and astigmatism.1 The results then, as today, demonstrated that ophthalmologists can do a good job of improving a patient’s visual acuity by performing cataract surgery with the simultaneous correction of refractive errors. Today, cataract surgery is looked upon as a refractive procedure that improves pre-existing refractive error and optimizes uncorrected visual acuity rather than solely as a means to treat a clouded crystalline lens.
Today's cataract procedure has enabled the use of small (less than 3.0 mm) incisions. With the development of laser phacoemulsification, phakonit, and newer technologies, surgeons will soon be able to use incisions as small as 1 mm or even smaller. These microincisions are placed through the clear cornea, which precludes the need for conjunctival dissection, cautery, sutures, injection anesthetics, bandaging and restriction of normal postoperative activities. Microincision cataract surgery has all but eliminated the complications of wound leak, uveal prolapse, and surgically-induced astigmatism. These advances have paved the way for faster, more efficient surgery, with less instruments, less intervention and faster visual recovery for the patient.
In 1994, I coined the term “keratolenticuloplasty” (KLP) to describe the simultaneous reshaping of the cornea (kerato) and replacing the lens with an IOL to correct refractive error (lenticuloplasty).1,2 Smaller-incision surgery has motivated IOL manufacturers to develop new intraocular silicone, acrylic, thermoplastic, and hydrogel lenses that can be injected through microincisions, replacing the rigid polymethylmethacrylate (PMMA) lenses of yesterday.
Along with these advances in microincision cataract surgery, have been the increasingly superior visual results patients have achieved.3,4 Myopia and hyperopia can be eliminated with IOL implantation, and astigmatism can be corrected with the use of a toric IOL with or without arcuate keratotomy incisions (the so-called limbal or peripheral corneal-relaxing incisions). Smaller-incision surgery has meant better results, fewer complications for patients, and fewer worries for surgeons.
I have developed and adhered to a single-incision single-instrument approach to cataract surgery,5-12 which has benefited my patients over the years. I use a clear corneal microincision, in-the-bag phacoemulsification with a mini-phaco flip maneuver, and injection of the IOL through the unenlarged incision.
Clear Corneal Refractive Surgical Procedure
Preoperative Evaluation and Surgical Plan
All cataract surgery patients undergo a comprehensive ophthalmic evaluation. In devising the surgical plan, cycloplegic refraction, combined with corneal topography and ultrasonic biometry, is used to select the best approach with the IOL for complete refractive correction. The aim is to fully correct the sphere for distance and to eliminate less than one diopter (D) of astigmatism with a single incision that doubles as the cataract incision, and to supplement the astigmatic correction for over 1 D with the toric IOL. The goal is to fully correct or slightly undercorrect the cylinder, and not overcorrect or shift the cylinder axis. To achieve the proper correction, preoperative data is entered on a worksheet (Fig. 1) and a surgical plan is developed.
Patients are administered topical 1% tropicamide in combination with 2.5% phenylephrine drops into the operative eye; 1 drop every 5 minutes is given 3 times, starting 15 minutes prior to surgery. When patients are called to surgery, they receive a single drop of 4% topical Betadine suspension. The surgical scrub is performed, and a sterile adhesive drape that excludes the eyelids and lashes is applied. Several drops of 2.5% tetracaine anesthetic are instilled; (if anesthetic drops are used prior to the procedure there may be excessive drying or sloughing of the corneal epithelium making visualization difficult).13,14 The Kershner reversible eyelid speculum (Rhein Medical, Tampa, Florida) is positioned under the eyelids and rotated out of the way so as to not interfere with the various steps of the procedure. The cornea is kept dry while the proper meridian of the cylinder is identified and marked with the inkless marker. The globe can be fixated with the disposable fixation ring if necessary, and the incisions are created.
A preoperative corneal topography scan is extremely valuable in both determining the qualitative appearance of the astigmatism as well as the location of the cylinder. This scan is also helpful for choosing whether to use symmetrical or asymmetrical incisions. Newer methods of corneal and intraocular analysis using wavefront analysis may also provide insight into higher-order aberrations that could affect postoperative refractive results. If the astigmatic correction is regular, clear, and present on a single meridian, then it is correctable. Surgeons should not correct irregular astigmatism, keratoconus, corneal scars and higher-order aberrations, in order to avoid corrections that could result in undesirable postoperative irregular corneas.
To assure a precise method to achieve better refractive outcomes, surgeons need to follow three rules: 1) Accurately measure astigmatism, 2) Apply the astigmatic correction on the proper meridian, and 3) Do not overcorrect the cylinder or shift from the pre-existing axis.
Prior to surgery, note in the patient’s chart the position of the patient’s steepest meridian on the cornea (Fig. 2). As all transverse or arcuate corneal incisions flatten the dome of the cornea, locate the incision on the steepest meridian.
Placing the incision anywhere other than the steepest part of the cornea will make the astigmatism worse. Since most elderly patients have against-the-rule astigmatism, temporal incisions typically work well for most, but not all, patients. These incisions are also best if the patient has a spherical cornea. Compared with the superior limbus, the temporal limbus is located further away from the optical center and is furthest away from the influence of the recti muscles. As a result, temporal incisions will create less induced corneal astigmatism.
Patients with significant pre-existing astigmatism will benefit from astigmatic keratotomy (keratolenticuloplasty) at the time of surgery. Limbal-relaxing incisions, because they are placed far peripherally in the corneal scleral limbus, have less flattening effect for a given length. As a result, they must be large to have any substantial effect on corneal curvature. When limbal incisions traverse 120 degrees of arc, they effectively denervate the cornea. In an elderly patient, this can mean an anesthetic cornea, severe dry eye, and corneal breakdown. Smaller, arcuate incisions have more effect with less surgery, and as long as they do not approach the central optical zone of the cornea, are less problematic.
For astigmatically-neutral clear-corneal incisions, a one-step, plane-parallel clear-corneal incision is used. A 2.4-mm disposable keratome can be used to create the proper architecture for a clear-corneal incision that will be self-sealing and maintain a width-to-height ratio of 3:2. If the width of the incision is 3 mm, the tunnel length through the cornea should be approximately 2 mm. In the KLP technique, the cataract incision is used for all the subsequent surgical steps in order to optimize the refractive results. The cataract incision itself can correct up to 1.5 D of astigmatism alone when used in a length of approximately 3 mm or less (Table I)
For an astigmatically-neutral incision, a single-plane incision is created with the keratome (Fig. 2a). For less than 1 D of astigmatism, a two-step clear-corneal incision is utilized to flatten in the meridian in which it is placed (Fig. 2b). By using an accurate depth blade set at a depth of 550 to 600 microns, the incision is made vertically, perpendicular to the cornea. Position the blade handle towards the center of the globe to create a deep groove approximately 85% of the corneal depth. The keratome is selected to fit the phacoemulsification tip and the IOL injector. (I usually use a 2.6 mm blade). The blade is positioned at the base of the incision and enters the eye in a plane-parallel fashion. This creates a two-step clear-corneal self-sealing incision with maximal flattening effect.
To correct astigmatism greater than 2 D (Fig. 2c), the cataract incision is coupled with an additional arcuate incision on the opposite meridian from the cataract incision (at an optical zone of 9, 10, or 11 mm to induce further flattening), or combined with the implantation of the toric IOL (Table II) (Staar Surgical, Monrovia, California). The toric IOL is presently available in two cylinder powers with the anterior surface of the lens delivering the refractive torus. The 2 D lens will deliver approximately 1.4 D of astigmatic correction at the spectacle plane, and the 3.5 D lens will provide approximately 2.3 D of correction.
The incisions are constructed15 using the disposable Becton Dickinson clear cornea incision system (Becton Dickinson Ophthalmic Surgery, Waltham Massachusetts), which is comprised of a hinged fixation ring, an accurate depth blade to make the vertical component of the incision, and a slit blade to make the proper architecture for corneal entry (Figs. 3, 4).
Next, the cornea is coated with several drops of 2.5% hydroxypropylmethylcellulose (HPMC), which covers the cornea, keeps it moist, protects it, eliminates the need for irrigation during the procedure, and provides 1.5 X magnification. Hyaluronate viscoelastic (Healon or Healon 5, Pharmacia, Peapack, New Jersey) is instilled into the anterior chamber.
The Kershner one-step forceps (Rhein Medical, Tampa, Florida) is used to create a 5-mm, round, central capsulotomy (Fig. 5).15,16 Hydrodissection is carried out using a Binkhorst cannula and balanced salt solution irrigation (Fig. 6), beginning with subincisional cortex to make sure that this is loosened prior to the phacoemulsification procedure.17
Today's techniques of topical anesthesia, clear corneal cataract surgery, and injection of elastic IOLs through small microincisions have placed new constraints on the ability of the surgeon to perform phacoemulsification. Introducing the phacoemulsification tip through a small, clear corneal refractive microincision limits access to the cataract and can restrict the surgeon's ability to manipulate the lens within the capsular bag (Fig. 7).
Many surgeons make two incisions through the cornea and use two instruments for phacoemulsification, one for the phacoemulsification tip and one for a sideport lens-manipulating instrument. I do not believe that a second-handed instrument is necessary for effective and efficient phacoemulsification of the cataract. There are distinct advantages of maintaining the phacoemulsification incision to one incision. Placing an additional incision in the eye is not only unnecessary but it increases the likelihood of incisional leaks, introduces an additional portal for infection and synechiae, and results in excessive instrumentation in the eye.
Single-Incision Phacoemulsification — Three-Step Keyhole Technique
The single incision/single instrument phacoemulsification technique is also known as a "one-handed" phaco technique. The maneuvers of lens rotation and segmental removal of the cataract can be performed with a single hand on the instrument, thus freeing the other hand for manipulating the eye, stabilizing of the globe, retrieving instruments, or stabilizing the phacoemulsification handle and tubing. It is important that the surgeon masters the ability to perform efficient phacoemulsification through a small corneal microincision before he or she adopts a single-incision technique. Single incision/single instrument phacoemulsification is a three-step method that I call the “keyhole” technique.
Step 1: central sculpting. When performing central sculpting, occlusion of the phacoemulsification tip rarely occurs. The goal of central sculpting is to remove the densest, hardest part of the nucleus at the beginning of the procedure when it is easiest to do so. The lens is kept entirely within the capsular bag. Using the phacoemulsification tip, gentle sculpting of the central nucleus is completed. If the lens nucleus is dense, a deep and wide sculpting is performed. If the lens is soft, a narrow and shallow sculpting is performed.
Step 2: segmental removal of the cortical rim — the keyhole method. Once central sculpting is completed, a cortical bowl remains. To remove the cortical bowl, a notch of the cortical rim is aspirated to release the tension on the cortical ring of the cataract in the peripheral cortex. Using the phacoemulsification tip as a fulcrum, the remaining cortical rim can be gently rotated clockwise. Two “clock-hours” of cortical rim are then gently aspirated into the central “triangle of safety,” and with minimal phacoemulsification are removed.
Step 3: removal of the nuclear plate. Following complete removal of the cortical rim, a small, flat section of the posterior nucleus remains. To remove this without risking injury of the posterior capsule, I use a mini phaco-flip technique. The phacoemulsification tip is used to push the tip of the nucleus plate against the equator of the capsule and flip it over. Using short bursts of phacoemulsification power, the final piece of the posterior nucleus can be safely elevated off the posterior capsule and removed. The clear corneal irrigation-aspiration tip is introduced to remove residual cortex and to irrigate the capsular bag.
Insertion of the IOL
The capsular bag is inflated with enough viscoelastic to open the capulorrhexis while being careful not to overfill the chamber (Fig. 8). Next, the 911A Tecnis aspheric IOL (Pharmacia, Peapack, New Jersey) or the silicone toric IOL (STAAR Surgical, Monrovia, California) is selected and loaded into the injector cartridge. The IOL is then passed through the incision into the capsular bag at the proper meridian, where it is allowed to position itself without additional manipulation (Fig. 9).
The injector is then withdrawn from the incision. Irrigation and aspiration are used to remove residual viscoelastic. The lens position is checked for proper centration, and the eye is reinflated to 20 mm Hg. A subconjunctival injection of 0.1 mL of betamethasone (Celestone) and 0.1 mL of cefazolin (Ancef) is injected.18 The patient is given artificial tear drops to be used as needed. No bandage is provided, but the patient is given a pair of sunglasses to be used outdoors. The patient is seen on day 1, and at 2 weeks, 3 months, 6 months, and 1 year postoperatively and annually thereafter. If a yittrium-aluminum-garnet (YAG) laser capsulotomy is required, it is not performed until after the 3-month postoperative visit.
A Prospective Study of 690 Patients
Data were analyzed prospectively for 690 consecutive clear corneal cataract procedures between March 1993 and March 1995 with follow-up from 24 months to 5 years. Each patient underwent cataract removal with topical anesthesia, clear corneal incision fashioned as an arcuate keratotomy to correct preexisting astigmatism, intercapsular phacoemulsification, and microinjection of a single-piece elastic IOL into the capsular bag to correct spherical error. Preoperatively, best corrected visual acuity was less than 20/50 (6/15) in all patients; 58% were myopic, 32% were hyperopic, and 57% had astigmatism of greater than 1 D.
Of the 690 patients who were included in the prospective study, postoperative spectacle independence was achieved with uncorrected vision of 20/40 (6/12) or better in 600 patients (87% of eyes). A total of 200 patients (29%) could read without the need for near correction. The sphere was fully corrected in 538 patients (78%), and was corrected within 1 D in 117 patients (17%) and within 2 D in 34 patients (5%). No patients were overcorrected. The cylinder was fully corrected in 497 patients (72%), and was corrected within 1 D in 194 patients (26%) and within 2 D in 14 patients (2%). In patients with residual astigmatism, there was no significant postoperative shift in cylinder axis. There were no sight-threatening complications. All patients were able to resume normal unrestricted activities within 24 hours of undergoing surgery.
The refractive outcomes achieved by following these techniques are the best we have ever achieved, and with incision sizes approaching 1 mm, this technology holds promise for even greater advances in the not-too-distant future. Both the sphere and the cylinder can be predictably corrected with clear corneal cataract surgery. Most patients can return to normal activities the same day. Because the incision size is so small, the need for long-term, postoperative eye-drop therapy is unnecessary. As a result, this procedure lowers costs, decreases the number of postoperative visits that are required, reduces patient inconvenience, reduces dependence on sunglasses, and increases patient satisfaction.
Although surgeons can deliver superior uncorrected visual acuity following cataract surgery using microincisions and insertion of toric IOLs to correct astigmatism,19-21 there have been few surgical options to correct presbyopia. Multifocal or bifocal IOLs are plagued with optical aberrations and loss of contrast sensitivity, and therefore should not be used in any but the simplest cases. Most cataract patients who need refractive correction for near tasks will need to use low-power reading spectacles. Perhaps in the future, a high-quality refractive correction for both near and far vision will be achievable with surgery. Work on the aspheric IOL is presently underway (Tecnis Z-9000 IOL-Pharmacia, Peapack, New Jersey) and appears promising.
I would encourage surgeons to consider switching to topical anesthesia and small clear corneal incisions. This surgical approach saves time. Patients love the fact that their eyes are fully functional and appear normal almost as soon as they leave the operating room.22-24 Because the results are better, more surgeons are mastering the finesse of this technique and more patients are demanding the rapid recovery and clear uncorrected vision that this procedure provides. By incorporating the surgical steps described earlier, surgeons will save time, avoid complications, and allow their patients to benefit from the advantages of clear corneal cataract surgery.
Many surgeons have been slow to accept the techniques of astigmatism management combined with cataract surgery. This may be due to resistance in acquiring new skills or to the unavailability of new instruments. Some of us may wrongly assume that better uncorrected vision following cataract surgery is difficult to achieve. In the United States, there is no extra reimbursement for taking the time to create better visual outcomes for patients, so some surgeons may feel that there is no benefit to surgeons. I believe that these techniques should be embraced by all surgeons. Astigmatism should be corrected, because it improves patients’ quality of life, and because it can be predictably and easily be accomplished using techniques that are currently available. By simply adopting a few sound fundamental principals and making a minimal investment in new instruments, surgeons can offer better refractive results for their patients.
Today’s modern techniques of microincision cataract surgery have enabled surgeons to fully correct refractive error at the time of cataract removal and IOL implantation. Smaller, more flexible, injectable, IOLs combined with more efficient methods of phacoemulsification have made it possible to use incision sizes that are smaller than 2.5 mm (and as small as 1 mm). Judicious selection of the IOL type (such as the use of toric and aspheric IOLs ) combined with astigmatic correction, can maximize refractive outcomes for cataract patients. This translates into more satisfied patients with fewer postoperative complications, less need for postoperative care, and less need for multiple refractive measurements following surgery.
Today’s surgeons have within their grasp the techniques for optimizing the refractive results of cataract surgery. Full refractive correction at the time of cataract surgery can and should be accomplished, and should be the goal of every cataract surgeon. Our patients should expect nothing less.
1. Kershner RM. ed. Refractive keratotomy for cataract surgery and the correction of astigmatism. Thorofare, NJ: Slack, 1994.
2. Kershner RM. Keratolenticuloplasty: arcuate keratotomy for cataract surgery and astigmatism. J Cataract Refract Surg 1995; 21: 274-277.
3. Kershner RM. Clear corneal cataract surgery and the correction of myopia, hyperopia and astigmatism. Ophthalmology 1997; 104(3): 381-389.
4. Kershner RM. How to be a hero to your patients: refractive cataract surgery. Rev Ophthalmol June1996: 50-54.
5. Kershner RM. Clinical consultation - single instrument phaco and continuous curvilinear capsulorhexis. Ophthalmic Practice 1994; 12(1):
6. Kershner, RM. “Single-Incision Phacoemulsification-The Three-Step Keyhole Technique” Cataract and Refractive Surgery Today November/December 2001, 21-24.
7. Kershner RM. Sutureless one-handed intercapsular phacoemulsification: the keyhole technique. J Cataract Refract Surg 1991; 17(suppl): 719-725.
8. Kershner RM. "Phacoemulsification Through a Clear Corneal Microincision" Phacoemulsification, Laser Cataract Surgery and Foldable IOLs Eds. Agarwal, Agarwal, Sacedev, Fine and Agarwal. New Dehli, India: Jaypee Brothers,1998, pp. 118-114.
9. Kershner RM. The case for one-handed clear corneal cataract surgery. Rev Ophthalmol 1998; 3: 68-73.
10. Kershner RM. "Single Instrument Phacoemulsification" Phacoemulsification, Laser Cataract Surgery and Foldable IOLs 2nd Edition, Eds. Agarwal, Agarwal, Sacedev, Fine and Agarwal. New Delhi, India: Jaypee Brothers, 2000, pp. 146-150
11. Kershner RM. Six tips to clear cornea cataract surgery. Rev Ophthalmol 1999; VI(4): 120
12. Kershner RM. “Clear Corneal Incision System for Cataract Surgery” Refractive Surgery Eds Agarwal, Agarwal, Agarwal. New Delhi, India: Jaypee Brothers, 1999
13. Kershner RM. Topical anesthesia for small incision self-sealing cataract surgery - a prospective study of the first 100 patients. J Cataract Refract Surg 1993; 19(3): 290-292.
14. Kershner RM. Topical anesthesia cataract surgery. Ophthalmic Practice 1993; 11(4): 160-165.
15. Kershner RM. One-step forceps for capsulorhexis. J Cataract Refract Surg 1990; 16: 762-765.
16. Kershner RM. Embryology, anatomy and needle capsulotomy. In: Koch PS, Davison JA, eds. Textbook of Advanced Phacoemulsification Techniques. Thorofare, NJ: Slack, 1991;35-48.
17. Kershner RM. Capsular rupture at hydrodissection. J Cataract Refract Surg 1992; 18: 201.
18. Kershner RM. Antibacterial prophylaxis before, during and after routine cataract surgery. In: Masket S, ed. Consultative Section. J Cataract Refract Surg 1993; 19(1): 110.
19. Kershner RM. Toric lenses for correcting astigmatism in 130 eyes (Discussion). Ophthalmology 2000; 107: 1776-1782.
20. Kershner, RM "Refractive Keratotomy and the Toric IOL for the Correction of Astigmatism in Clear Cornea Cataract Surgery " in James Gills, M.D., Editor A Complete Guide to Astigmatism Management Slack, Inc. 2002.
21. Kershner, RM. "Clear Cornea Cataract Surgery and the Collamer IOL", Vision and Aging, October, 2001.
22. Kershner RM. Refractive cataract surgery. Curr Opin Ophthalmol 1998; 9(1): 46-54.
23. Kershner RM. Patient's adaptation to cataract surgery. Ophthalmology 1998; 105(1): 6-7.
24. Kershner, RM "Optimizing the Refractive Outcomes of Clear Cornea Cataract Surgery" Highlights of Ophthalmology-Phaco, Phakonit and Laser Phaco, Benjamin Boyd, MD, Eds. Agarwal, S, Agarwal, A, Agarwal, A. Chapter 9, 2002.
Fig. 1 The Kershner clear corneal cataract surgery preoperative worksheet
Fig. 2 Location and architecture of clear corneal arcuate astigmatic incisions. Reprinted from: Kershner, RM. “Clear Cornea Cataract Surgery and the Correction of Myopia, Hyperopia and Astigmatism.” Ophthalmology 1997;104:381-389.
a. Single, clear corneal, 2.5 mm planar, stab incision on the oblique or temporal limbus for astigmatic neutrality, to correct less than 1 D of astigmatism.
b. Single, clear corneal, 2.5 mm arcuate incision on the steepest axis at the 10 mm optical zone to correct 1 D or less of astigmatism or a single 3.0 mm arcuate incision on the steepest axis at a 9 mm optical zone, to correct 1 to 2 D of astigmatism.
c. Two arcuate keratotomy incisions are placed according to the nomograms to correct greater than 2 D of astigmatism.
Fig. 3 A disposable Clear Cornea Incision System (Becton Dickinson) can be used to create the ideal corneal incisions for refractive cataract surgery.
Fig. 4 The location is marked and the incision created.
Fig. 5 The one-step capsulorrhexis forceps creates a round central 5.0mm capsulorrhexis.
Fig. 6 Hydrodissection loosens sub-incisional cortex.
Fig. 7 Phacoemulsification is carried out within the capsular bag with a 3-step technique.
Fig. 8 The capsular bag is inflated with viscoelastic.
Fig. 9 The IOL is loaded into the injection cartridge and injected.
Table I Incision guideline for clear corneal cataract surgery
Correction Optical Zone Number of Arcuate Incision
(Diopters) (mm) Incisions Length (mm)
<1.0 10 1 2.5
1.0 9 1 2.5
1.5 9 1 3.0
2.0 8 2 2.5
2.5 8 2 3.0
3.0 7 2 2.5
3.5 7 2 3.0
4.0 6 1 2.5
10 1 2.5
4.5 6 1 3.0
10 1 2.5
5.0 6 1 3.0
10 1 2.5
5.5 5 1 2.5
10 1 2.5
6.0 5 1 3.0
10 1 3.0
This nomogram is to be used when incisions alone are utilized to correct the cylinder. They are a guideline only, surgeons should adjust for the desired result. Corrected for age 60+. Arcs placed on steepest axis of astigmatism (plus cylinder). Pachymetry at incision site, keratome set to 95% of pachymetry (550-600 microns). Mark arcuate incisions and optical zone with Kershner One-Step Marker. Cataract keratotomy at 10 mm, 9 mm, or 8 mm only.
Table II Incision guideline for clear corneal cataract surgery with a toric IOL.
Correction Optical Zone Number of Arcuate Incision Toric
(Diopters) (mm) Incisions Length (mm) IOL
<1.0 10 1 2.5
1.0 9 1 2.5
1.5 9 1 3.0 +2.00 toric
2.0 9 1 3.0 +2.00 toric
2.5 9 1 3.0 +3.50 toric
3.0 9 2 3.5 +3.50 toric
3.5 8 1 3.0 +3.50 toric
10 1 3.0 +3.50 toric
4.0 8 1 3.5 +3.50 toric
10 1 3.5
4.5 8 1 4.0 +3.50 toric
10 1 4.0
5.0 8 1 4.5 +3.50 toric
10 1 4.5
5.5 8 1 5.0 +3.50 toric
10 1 5.0
6.0 8 1 5.5 +3.50 toric
10 1 5.5
This nomogram is to be used when incisions are utilized in combination with the toric IOL to correct the cylinder. They are to be used a a guideline only, surgeons should adjust for the desired result. Corrected for age 60+. Arcs placed on steepest axis of astigmatism (plus cylinder). Pachymetry at incision site, keratome set to 95% of pachymetry (550-600 microns). Mark arcuate incisions and optical zone with Kershner One-Step Marker. Cataract keratotomy at 10 mm, 9 mm, or 8 mm only.