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Keratolenticuloplasty: Arcuate keratotomy for cataract surgery and astigmatism
Keratolenticuloplasty: Arcuate keratotomy for cataract surgery and astigmatism Robert M. Kershner, M.D.
ABSTRACT Cataract surgery has evolved into a procedure in which pre-existing refractive errors can be corrected simultaneously to improve uncorrected visual acuity following surgery. This paper describes keratolenticuloplasty, a new technique of clear corneal arcuate keratotomy for cataract surgery that corrects pre-existing astigmatic errors at the time of cataract extraction. This technique uses topical anesthesia, a single pair of arcuate corneal incisions placed on the steepest axis of astigmatism, one-step capsulerhexis, hydrodissection, intercapsular phacoemulsification, and injection of an elastic intraocular lens within the capsular bag. The technique has been used in over 1,000 patients with follow-up of 24 months. Uncorrected visual acuity of 20/40 or better with no associated complications was achieved in 96% of patients. Key Words: arcuate keratotomy, astigmatism, clear corneal cataract surgery, keratolenticuloplasty, keratotomy, topical anesthesia
Cataract surgery has undergone a tremendous evolution in the past several years. Today, cataracts can be removed through clear corneal incisions of 2.5 mm, using only topical anesthesia without suture closure or postoperative bandaging. Accurate ultrasonic biometry has resulted in successful correction of hyperopic and myopic refractive errors with intraocular lens (IOL) implantation. However, pre-existing astigmatic refractive errors persist as the leading indication for postoperative spectacle correction. This paper describes a simplified technique that combines arcuate astigmatic keratotomy with cataract surgery to correct pre-existing astigmatism. One arcuate, clear corneal incision is then used for cataract removal and IOL implantation. I have named this procedure keratolenticuloplasty to reflect the remodeling of the cornea and the replacement of the lens through a corneal incision to achieve emmetropia in a cataract patient.
SURGICAL TECHNIQUE This entire procedure is performed under 0.5% tetracaine eyedrops using a topical anesthesia procedure well described in the literature. 1- 4 The patient fixates
on the light of the operating microscope, enabling the surgeon to accurately place the marks for the keratotomy incisions. Careful preoperative keratometry is obtained with corneal topographic analysis. Meticulous ultrasonic biometry is performed to determine the proper spherical correction to be provided by the IOL. A surgical plan is then constructed based on the amount of astigmatism indicated by cycloplegic refraction and evaluation of the preoperative corneal 5 topography using published nomograms. Ultrasonic pachymetry is measured at the incision sites. Surgical scrub is performed and an eyelid speculum placed. The axis of the steepest astigmatism (plus cylinder) is identified through the objectives of the operating microscope in which an astigmatic reticle is installed. The patient is asked to visualize the center of the light from the operating microscope. The proper Kershner one-step arcuate keratotomy marker (Figure 1) is selected corresponding to the degree of astigmatism to be corrected. The marker is lightly pressed onto the cornea while centered over the corneal light reflex (Figure 2). Two 3 mm arcuate marks are
Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, April /994. The author has no proprietary or financial interest in the technique or instrumentation described in this paper. Reprint requests to Robert M. Kershner, M.D., Orange Grove Center for Corrective Eye Surgery, 1925 West Orange Grove Road, Suite 303, Tucson, Arizona 85704. 274
J CATARACT REFRACT SURG-VOL 21, MAY 1995
Fig. 1.
(Kershner) Side profile of Kershner arcuate marker.
Fig. 3.
(Kershner) Two arcuate marks are created.
then positioned at the proper optical zone and axis (Figure 3). A square, triple-edged, diamond keratome is examined under the calibrating microscope and set to 100% of pachymetry measurement taken at the incision sites (Figure 4). The keratome is used to incise an arcuate incision of the proper length. This is achieved by holding the instrument between the index finger and the thumb and slightly rotating clockwise in the direction of the incision paralleling the optical zone. The arcuate keratotomy closest to the surgeon is used for the cataract procedure. A 2.5 mm trifacet diamond keratome is positioned at the base of the arcuate keratotomy, and entrance into the anterior chamber is achieved 1.25 mm perpendicular to the base of the incision (Figure 5). The anterior chamber is inflated with sodium hyaluronate (Healon®). A one-step, 4.0 mm round central capsulorhexis is performed. 6 •7 Hydrodissection is carried out with a curved cannula and balanced salt solution irrigation, completely separating the cortex from the lens capsule. Intercapsular
phacoemulsification is performed using the onehanded keyhole technique. 8 The capsular bag is inflated with viscoelastic. A single-piece silicone elastic lens (Staar AA4203) is then loaded into the injection cartridge with a single drop of balanced salt solution (Figure 6). The cartridge is positioned through the keratotomy incision and the lens gently released into the capsular bag. Irrigation and aspiration of residual viscoelastic material is performed and the anterior chamber reinflated with balanced salt solution (Figure 7). Topical antibiotic eyedrops are instilled, and the patient is discharged without a patch.
Fig. 2.
Fig. 4.
(Kershner) The marker is positioned to center the optical zone and the arcs along the steepest axis of astigmatism.
RESULTS Over 1000 patients have had this procedure with follow-up of at least 24 months. Preoperative refractive error averaged -1.25 sphere + 1.50 cylinder (range -16 to +6 sphere, +0.75 to +7.00 cylinder).
(Kershner) The square diamond keratome is set to 100% of pachymetry. Each arcuate incision is incised.
JCATARACIREFRACTSURG-VOL21, MAY 1995
275
Fig. 5.
(Kershner) A 2.5 mm trifacet diamond keratome is placed perpendicular to the base of the arcuate incision closest to the surgeon entering the anterior chamber 1.25 mm distal to the keratotomy. This creates a two-step clear corneal incision that is self-sealing.
Eighty-five percent of the patients had plus cylinder within 15 degrees of the 180-degree axis. The remainder were at 90 degrees or oblique axis. Postoperative refraction averaged -0.75 sphere +0.50 cylinder (range -1.50 to plano sphere, plano to 1.00 cylinder). Uncorrected visual acuity of 20/40 or better was achieved in 96% of patients, excluding those with pre-existing macular disease. There were no complications from the keratolenticuloplasty procedure. Four patients had overcorrected astigmatic errors, resulting in a shift in astigmatism of +0.50 to +2.00 in the opposite meridian. This occurred early in the series and was corrected by modifying the nomograms.
CONCLUSION This study demonstrates that most astigmatic refractive errors can be safely and effectively cor-
Fig. 6. 276
(Kershner) A 2.5 mm injection cartridge is used to insert a one-piece elastic lens into the capsular bag.
Fig. 7.
(Kershner) The IOL at the conclusion of surgery. The arcuate keratotomy incision does not interfere with visualization.
rected at the time of cataract surgery by using a simple, planned approach. The use of the one-step arcuate keratotomy marker simplifies the location of the visual axis and optical zone and simultaneous placement of the arcuate marks. Utilizing the arcuate keratotomy closest to the surgeon allows the subsequent steps of cataract surgery to be performed without creating an additional incision. Operating on the steepest axis almost always reduces the preexisting astigmatic error. Pairing that incision with an additional arcuate keratotomy on the opposite arm of the astigmatic steep meridian allows correction for much larger degrees of astigmatism. Surgeons who use the keratolenticuloplasty technique should aim to slightly undercorrect pre-existing astigmatism. More astigmatic surgery can always be done as a separate procedure. However, it may be difficult to undo what is already done if too great a correction is achieved. The surgeon should use the following guidelines when using this technique: 1. Avoid placing the arcuate incision inside the 7 mm optical zone. It is preferable to achieve the astigmatic correction with a larger arc at a larger optical zone than to make a smaller incision at an optical zone closer to the visual axis. 2. Arcuate incisions should never exceed 90 degrees in length in any optical zone. 3. At least 85% of corneal depth is required for the ideal astigmatic effect. 4. Whenever possible, a single arcuate incision at the site of cataract surgery corresponding to the steepest axis of astigmatism is preferable to two incisions. 5. The arcuate incision closest to the surgeon for subsequent cataract surgery should be limited to the 7 mm optical zone. Avoid using the arcuate incision
J CATARACT REFRACT SURG-VOL 21, MAY 1995
for subsequent cataract surgery if the incision is closer to the optical center of the eye than the 7 mm optical zone. 6. Do not press on the globe with another instrument when creating the incision to avoid full-thickness penetration. 7. The astigmatic marks are easier to visualize if the cornea is kept slightly dry. 8. Avoid using marking inks that may obscure visualization for subsequent surgical maneuvers. 9. Arcuate keratotomy incisions on the axis of the steepest astigmatism will almost always improve the postoperative refractive result, while operating on the incorrect axis will almost always make the refractive result worse. Be sure to verify the correct axis before making the incisions. 10. Consult established nomograms. My nomograms for the one-step arcuate keratotomy system and those of others have been published. 5 Individual variations will require surgeons to tailor their surgical result based on the instrumentation they use and their experience. Arcuate keratotomy combined with cataract surgery is one of the most powerful techniques available today for correcting pre-existing refractive errors. The keratolenticuloplasty method simplifies the approach by maximizing the astigmatic correction using the refractive power of the cataract incision. With experience, the method can become a
very effective surgical tool for improving patients' postoperative visual result. REFERENCES 1. Kershner RM. No-stitch topical anesthesia. In: Gills 1P, Hustead RF, Sanders DR, eds, Ophthalmic Anesthesia. Thorofare, N1, Slack, 1993; 172-175 2. Kershner RM. Topical anesthesia for small incision self-sealing cataract surgery; a prospective evaluation of the first 100 patients. 1 Cataract Refract Surg 1993;
19:290-292 3. Kershner RM. Corneal anatomy and the no-touch technique. In: Fine IH, Fichman RA, Grabow HB, eds, Clear-Corneal Cataract Surgery and Topical Anesthesia. Thorofare, N1, Slack, 1993; 79-84 4. Kershner RM. Cataract surgery technique using topical anesthesia. In: Fine H, Fichman' RA, Grabow HB, eds, Clear-Corneal Cataract Surgery and Topical Anesthesia. Thorofare, N1, Slack, 1993; 141-153 5. Kershner RM, ed. Refractive Keratotomy for Cataract Surgery and the Correction of Astigmatism. Thorofare, N1, Slack, 1994 6. Kershner RM. One-step forceps for capsulorhexis. 1 Cataract Refract Surg 1990; 16:762-765 7. Kershner RM. Embryology, anatomy and needle capsulotomy. In: Koch PS, Davison 1A, eds, Textbook of Advanced Phacoemulsification Techniques. Thorofare, N1, Slack, 1991; 35-48 8. Kershner RM. Sutureless one-handed intercapsular phacoemulsification; the keyhole technique. 1 Cataract Refract Surg 1991; 17:719-725
J CATARACT REFRACT SURG-VOL 21, MAY 1995
277
ABSTRACT Cataract surgery has evolved into a procedure in which pre-existing refractive errors can be corrected simultaneously to improve uncorrected visual acuity following surgery. This paper describes keratolenticuloplasty, a new technique of clear corneal arcuate keratotomy for cataract surgery that corrects pre-existing astigmatic errors at the time of cataract extraction. This technique uses topical anesthesia, a single pair of arcuate corneal incisions placed on the steepest axis of astigmatism, one-step capsulerhexis, hydrodissection, intercapsular phacoemulsification, and injection of an elastic intraocular lens within the capsular bag. The technique has been used in over 1,000 patients with follow-up of 24 months. Uncorrected visual acuity of 20/40 or better with no associated complications was achieved in 96% of patients. Key Words: arcuate keratotomy, astigmatism, clear corneal cataract surgery, keratolenticuloplasty, keratotomy, topical anesthesia
Cataract surgery has undergone a tremendous evolution in the past several years. Today, cataracts can be removed through clear corneal incisions of 2.5 mm, using only topical anesthesia without suture closure or postoperative bandaging. Accurate ultrasonic biometry has resulted in successful correction of hyperopic and myopic refractive errors with intraocular lens (IOL) implantation. However, pre-existing astigmatic refractive errors persist as the leading indication for postoperative spectacle correction. This paper describes a simplified technique that combines arcuate astigmatic keratotomy with cataract surgery to correct pre-existing astigmatism. One arcuate, clear corneal incision is then used for cataract removal and IOL implantation. I have named this procedure keratolenticuloplasty to reflect the remodeling of the cornea and the replacement of the lens through a corneal incision to achieve emmetropia in a cataract patient.
SURGICAL TECHNIQUE This entire procedure is performed under 0.5% tetracaine eyedrops using a topical anesthesia procedure well described in the literature. 1- 4 The patient fixates
on the light of the operating microscope, enabling the surgeon to accurately place the marks for the keratotomy incisions. Careful preoperative keratometry is obtained with corneal topographic analysis. Meticulous ultrasonic biometry is performed to determine the proper spherical correction to be provided by the IOL. A surgical plan is then constructed based on the amount of astigmatism indicated by cycloplegic refraction and evaluation of the preoperative corneal 5 topography using published nomograms. Ultrasonic pachymetry is measured at the incision sites. Surgical scrub is performed and an eyelid speculum placed. The axis of the steepest astigmatism (plus cylinder) is identified through the objectives of the operating microscope in which an astigmatic reticle is installed. The patient is asked to visualize the center of the light from the operating microscope. The proper Kershner one-step arcuate keratotomy marker (Figure 1) is selected corresponding to the degree of astigmatism to be corrected. The marker is lightly pressed onto the cornea while centered over the corneal light reflex (Figure 2). Two 3 mm arcuate marks are
Presented at the Symposium on Cataract, IOL and Refractive Surgery, Boston, April /994. The author has no proprietary or financial interest in the technique or instrumentation described in this paper. Reprint requests to Robert M. Kershner, M.D., Orange Grove Center for Corrective Eye Surgery, 1925 West Orange Grove Road, Suite 303, Tucson, Arizona 85704. 274
J CATARACT REFRACT SURG-VOL 21, MAY 1995
Fig. 1.
(Kershner) Side profile of Kershner arcuate marker.
Fig. 3.
(Kershner) Two arcuate marks are created.
then positioned at the proper optical zone and axis (Figure 3). A square, triple-edged, diamond keratome is examined under the calibrating microscope and set to 100% of pachymetry measurement taken at the incision sites (Figure 4). The keratome is used to incise an arcuate incision of the proper length. This is achieved by holding the instrument between the index finger and the thumb and slightly rotating clockwise in the direction of the incision paralleling the optical zone. The arcuate keratotomy closest to the surgeon is used for the cataract procedure. A 2.5 mm trifacet diamond keratome is positioned at the base of the arcuate keratotomy, and entrance into the anterior chamber is achieved 1.25 mm perpendicular to the base of the incision (Figure 5). The anterior chamber is inflated with sodium hyaluronate (Healon®). A one-step, 4.0 mm round central capsulorhexis is performed. 6 •7 Hydrodissection is carried out with a curved cannula and balanced salt solution irrigation, completely separating the cortex from the lens capsule. Intercapsular
phacoemulsification is performed using the onehanded keyhole technique. 8 The capsular bag is inflated with viscoelastic. A single-piece silicone elastic lens (Staar AA4203) is then loaded into the injection cartridge with a single drop of balanced salt solution (Figure 6). The cartridge is positioned through the keratotomy incision and the lens gently released into the capsular bag. Irrigation and aspiration of residual viscoelastic material is performed and the anterior chamber reinflated with balanced salt solution (Figure 7). Topical antibiotic eyedrops are instilled, and the patient is discharged without a patch.
Fig. 2.
Fig. 4.
(Kershner) The marker is positioned to center the optical zone and the arcs along the steepest axis of astigmatism.
RESULTS Over 1000 patients have had this procedure with follow-up of at least 24 months. Preoperative refractive error averaged -1.25 sphere + 1.50 cylinder (range -16 to +6 sphere, +0.75 to +7.00 cylinder).
(Kershner) The square diamond keratome is set to 100% of pachymetry. Each arcuate incision is incised.
JCATARACIREFRACTSURG-VOL21, MAY 1995
275
Fig. 5.
(Kershner) A 2.5 mm trifacet diamond keratome is placed perpendicular to the base of the arcuate incision closest to the surgeon entering the anterior chamber 1.25 mm distal to the keratotomy. This creates a two-step clear corneal incision that is self-sealing.
Eighty-five percent of the patients had plus cylinder within 15 degrees of the 180-degree axis. The remainder were at 90 degrees or oblique axis. Postoperative refraction averaged -0.75 sphere +0.50 cylinder (range -1.50 to plano sphere, plano to 1.00 cylinder). Uncorrected visual acuity of 20/40 or better was achieved in 96% of patients, excluding those with pre-existing macular disease. There were no complications from the keratolenticuloplasty procedure. Four patients had overcorrected astigmatic errors, resulting in a shift in astigmatism of +0.50 to +2.00 in the opposite meridian. This occurred early in the series and was corrected by modifying the nomograms.
CONCLUSION This study demonstrates that most astigmatic refractive errors can be safely and effectively cor-
Fig. 6. 276
(Kershner) A 2.5 mm injection cartridge is used to insert a one-piece elastic lens into the capsular bag.
Fig. 7.
(Kershner) The IOL at the conclusion of surgery. The arcuate keratotomy incision does not interfere with visualization.
rected at the time of cataract surgery by using a simple, planned approach. The use of the one-step arcuate keratotomy marker simplifies the location of the visual axis and optical zone and simultaneous placement of the arcuate marks. Utilizing the arcuate keratotomy closest to the surgeon allows the subsequent steps of cataract surgery to be performed without creating an additional incision. Operating on the steepest axis almost always reduces the preexisting astigmatic error. Pairing that incision with an additional arcuate keratotomy on the opposite arm of the astigmatic steep meridian allows correction for much larger degrees of astigmatism. Surgeons who use the keratolenticuloplasty technique should aim to slightly undercorrect pre-existing astigmatism. More astigmatic surgery can always be done as a separate procedure. However, it may be difficult to undo what is already done if too great a correction is achieved. The surgeon should use the following guidelines when using this technique: 1. Avoid placing the arcuate incision inside the 7 mm optical zone. It is preferable to achieve the astigmatic correction with a larger arc at a larger optical zone than to make a smaller incision at an optical zone closer to the visual axis. 2. Arcuate incisions should never exceed 90 degrees in length in any optical zone. 3. At least 85% of corneal depth is required for the ideal astigmatic effect. 4. Whenever possible, a single arcuate incision at the site of cataract surgery corresponding to the steepest axis of astigmatism is preferable to two incisions. 5. The arcuate incision closest to the surgeon for subsequent cataract surgery should be limited to the 7 mm optical zone. Avoid using the arcuate incision
J CATARACT REFRACT SURG-VOL 21, MAY 1995
for subsequent cataract surgery if the incision is closer to the optical center of the eye than the 7 mm optical zone. 6. Do not press on the globe with another instrument when creating the incision to avoid full-thickness penetration. 7. The astigmatic marks are easier to visualize if the cornea is kept slightly dry. 8. Avoid using marking inks that may obscure visualization for subsequent surgical maneuvers. 9. Arcuate keratotomy incisions on the axis of the steepest astigmatism will almost always improve the postoperative refractive result, while operating on the incorrect axis will almost always make the refractive result worse. Be sure to verify the correct axis before making the incisions. 10. Consult established nomograms. My nomograms for the one-step arcuate keratotomy system and those of others have been published. 5 Individual variations will require surgeons to tailor their surgical result based on the instrumentation they use and their experience. Arcuate keratotomy combined with cataract surgery is one of the most powerful techniques available today for correcting pre-existing refractive errors. The keratolenticuloplasty method simplifies the approach by maximizing the astigmatic correction using the refractive power of the cataract incision. With experience, the method can become a
very effective surgical tool for improving patients' postoperative visual result. REFERENCES 1. Kershner RM. No-stitch topical anesthesia. In: Gills 1P, Hustead RF, Sanders DR, eds, Ophthalmic Anesthesia. Thorofare, N1, Slack, 1993; 172-175 2. Kershner RM. Topical anesthesia for small incision self-sealing cataract surgery; a prospective evaluation of the first 100 patients. 1 Cataract Refract Surg 1993;
19:290-292 3. Kershner RM. Corneal anatomy and the no-touch technique. In: Fine IH, Fichman RA, Grabow HB, eds, Clear-Corneal Cataract Surgery and Topical Anesthesia. Thorofare, N1, Slack, 1993; 79-84 4. Kershner RM. Cataract surgery technique using topical anesthesia. In: Fine H, Fichman' RA, Grabow HB, eds, Clear-Corneal Cataract Surgery and Topical Anesthesia. Thorofare, N1, Slack, 1993; 141-153 5. Kershner RM, ed. Refractive Keratotomy for Cataract Surgery and the Correction of Astigmatism. Thorofare, N1, Slack, 1994 6. Kershner RM. One-step forceps for capsulorhexis. 1 Cataract Refract Surg 1990; 16:762-765 7. Kershner RM. Embryology, anatomy and needle capsulotomy. In: Koch PS, Davison 1A, eds, Textbook of Advanced Phacoemulsification Techniques. Thorofare, N1, Slack, 1991; 35-48 8. Kershner RM. Sutureless one-handed intercapsular phacoemulsification; the keyhole technique. 1 Cataract Refract Surg 1991; 17:719-725
J CATARACT REFRACT SURG-VOL 21, MAY 1995
277