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Correction of spherical myopia with a single 150-degree intrastromal corneal ring segment
Correction of spherical myopia with a single 150-degree intrastromal corneal ring segment Alan Sugar, MD A 47-year-old woman with an uncorrected visual acuity (UCVA) of 20/70 and a refraction of ⫺1.50 ⫹0.75 ⫻ 75 in the right eye had 2 0.25 mm intrastromal corneal ring segments (Intacs威) inserted uneventfully through a superior incision. The patient was hyperopic 2 years later with a refraction of ⫹0.50 ⫹0.75 ⫻ 25 and was intolerant of spectacles. She also complained of temporal glare. Twenty-seven months after insertion, the temporal ring segment was removed. Four months later, the UCVA was 20/20; with a refraction of plano ⫹0.50 ⫻ 35, the visual acuity was 20/15. Topography showed corresponding regular astigmatism, and the patient’s glare had resolved. Removal of 1 Intacs segment may be an option in cases of overcorrection after ring insertion for myopia. J Cataract Refract Surg 2004; 30:1127–1129 2004 ASCRS and ESCRS
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ntrastromal corneal ring segments (ICRSs) (Intacs威) have been approved in the United States for the treatment of low myopia with minimal astigmatism. These devices are effective and relatively safe.1 Intacs insertion involves placement of 2 150-degree plastic arcs in the deep corneal stroma. The rings increase the corneal thickness in the periphery, shortening the arc length of the central cornea and flattening it. Unlike procedures such as laser in situ keratomileusis (LASIK) that remove corneal tissue, the central cornea maintains a relatively physiologic prolate curvature.2 One concern is that astigmatism is induced by the rings themselves through the gap between the ring ends or through the insertion incision.3 Theoretically, induced astigmatism is partially prevented by symmetrical placement of the rings. Recently, ICRSs have been used to treat keratoconus and corneal ectasia after LASIK. For
Accepted for publication September 17, 2003. From W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA. The author has no financial or proprietary interest in any material or method mentioned. Reprint requests to Alan Sugar, MD, W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, 1000 Wall Street, Ann Arbor, Michigan 48105, USA. E-mail: [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
those purposes, the rings are usually placed horizontally with a thicker segment inferiorly and a thinner one superiorly to manage decentration and asymmetry of corneal astigmatism.4,5 Removal of ICRSs has been necessary in some patients with excessive symptoms of glare or halo or has been combined with an exchange to treat refractive overcorrection or undercorrection.6 A patient who had 1 ring segment removed for overcorrection is reported here.
Case Report Institutional review board approval and informed consent from the patient were obtained for this report. A 46-year-old woman presented to the center in September 1999 seeking decreased dependence on spectacles. The uncorrected visual acuity (UCVA) was 20/70 in each eye. Manifest and cycloplegic refractions were ⫺1.50 ⫹0.75 ⫻ 25 and ⫺1.75 ⫹0.75 ⫻ 164 for a visual acuity of 20/15– in both eyes. Near vision corrected well with a ⫹1.00 add. Slitlamp examination was normal. Central corneal thickness by ultrasound was 585 m in the right eye and 583 m in the left eye. Keratometry was 45.5 ⫻ 45.5 and 45.5 ⫻ 46.5@153, respectively. Topographies were normal. Refractive surgical options were discussed. The patient decided to proceed with ICRS insertion in the right eye only, allowing a trial period to maintain good uncorrected reading vision in the left eye. In October 1999, 2 0.25 mm Intacs 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2003.09.059
CASE REPORTS: SUGAR
Figure 1. (Sugar) Right eye 1 week after removal of the temporal ring segment.
rings were inserted uneventfully in the right eye through a superior incision with a 440 m depth. One week postoperatively, the UCVA was 20/30⫹ in the right eye; with a manifest refraction of ⫹1.50 sphere, the visual acuity was 20/20⫹. The ring segments were well
Figure 2. (Sugar) Orbscan elevation and power maps 5 months after removal of the temporal ring segment.
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centered and at about 60% depth. The patient complained of blurring in the right eye. The visual acuity remained unchanged over the following 6 months. Exchange of the 0.25 mm rings for 0.20 mm rings was discussed if the latter were approved by the U.S. Food and Drug Administration. Despite the trial period for spectacle correction, by August 2001, the patient could no longer tolerate the hyperopia and complained of temporal glare in the right eye. The manifest refraction was ⫹0.50 ⫹0.75 ⫻ 25. In November 2001, the temporal ring was removed under topical anesthesia using the technique described by Schanzlin et al.7 One week after the temporal ring was removed, the patient had no glare and the UCVA in the right eye was 20/20, correcting to 20/15 with plano ⫹0.50 ⫻ 35 (Figure 1). When the patient was examined in April 2002, the UCVA was 20/15 in the right eye and the manifest refraction was plano. The UCVA in the left eye was J1. Simulated keratometry was 44.1 ⫻ 44.9@78 in the right eye using Orbscan topography (Bausch & Lomb) (Figure 2).
Discussion Intacs are available in the U.S. in 5 thicknesses from 0.25 to 0.35 mm to correct –1.00 to –3.00 diopters of myopic spherical equivalent. With their semicircular configuration, they are not intended to correct astigmatism. Although added thickness does not occur in a complete circular arc of the corneal periphery, induced astigmatism has not been a major problem.3 The asymmetry of corneal thickness induced by the presence of a single ring segment might be expected to induce astigmatism in the meridian of the ring arc center or possibly in that hemimeridian alone. The astigmatism in the patient reported here was unchanged from preoperatively when both ring segments were present. After the removal of 1 segment, there was mild relative vertical steepening consistent with a small coupling effect of the horizontal flattening. Removal of ring pairs was reported in 8.70% of 449 eyes in the initial Intacs trials. The risk for removal was greatest for the thickest ring segments.6 The most frequent indications for removal were visual symptoms (51.00%) (eg, glare, halos, fluctuations, diplopia, and difficulty with night vision). Overcorrection or undercorrection was the indication for removal of 23.00% of segments. In many eyes, exchange of the ring segment for rings of different thicknesses corrects the ammetropia.8 In the patient reported here, the 0.25 mm ring segment would have been exchanged for a 0.20 mm segment if that size had been available.
J CATARACT REFRACT SURG—VOL 30, MAY 2004
CASE REPORTS: SUGAR
To my knowledge, details of single-ring removal have not been reported. Boxer Wachler9 mentions a single case but reports no specific data.9 Alio´ and coauthors10 report the removal of a single ring after using Intacs to treat post-LASIK ectasia but provide no details.10 Removal of 1 of 2 ring segments to decrease the refractive effect may be a reasonable alternative. If the effect is inadequate or visually significant astigmatism is induced, the second ring can be removed.
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References 1. Rapuano CJ, Sugar A, Koch DD, et al. Intrastromal corneal ring segments for low myopia; a report of the American Academy of Ophthalmology. (Ophthalmic Technology Assessment) Ophthalmology 2001; 108: 1922–1928 2. Holmes-Higgin DK, Burris TE. Corneal surface topography and associated visual performance with INTACS for myopia; phase III clinical trial results; the INTACS Study Group. Ophthalmology 2000; 107:2061–2071 3. Twa MD, Ruckhofer J, Schanzlin DJ. Surgically induced astigmatism after implantation of Intacs intrastromal
8.
9.
10.
corneal ring segments. J Cataract Refract Surg 2001; 27: 411–415 Lovisolo CF, Fleming JF. Intracorneal ring segments for iatrogenic keratectasia after laser in situ keratomileusis or photorefractive keratectomy. J Refract Surg 2002; 18: 535–541 Siganos CS, Kymionis GD, Kartakis N, et al. Management of keratoconus with Intacs. Am J Ophthalmol 2003; 135:64–70 Clinch TE, Lemp MA, Foulks GN, Schanzlin DJ. Removal of INTACS for myopia. Ophthalmology 2002; 109: 1441–1446 Schanzlin DJ, Abbott RL, Asbell PA, et al. Two-year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmology 2001; 108:1688– 1694 ¨O ¨ , Durrie DS, Lindstrom RL. Asbell PA, Uc¸akhan O Adjustability of refractive effect for corneal ring segments. J Refract Surg 1999; 15:627–631 Boxer Wachler BS. Therapeutic uses of intracorneal corneal ring segments. Refractive Eyecare for Ophthalmologists, 2001; 5(12):12–16 Alio´ JL, Salem TF, Artola A, Osman AA. Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:1568–1574
J CATARACT REFRACT SURG—VOL 30, MAY 2004
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I
ntrastromal corneal ring segments (ICRSs) (Intacs威) have been approved in the United States for the treatment of low myopia with minimal astigmatism. These devices are effective and relatively safe.1 Intacs insertion involves placement of 2 150-degree plastic arcs in the deep corneal stroma. The rings increase the corneal thickness in the periphery, shortening the arc length of the central cornea and flattening it. Unlike procedures such as laser in situ keratomileusis (LASIK) that remove corneal tissue, the central cornea maintains a relatively physiologic prolate curvature.2 One concern is that astigmatism is induced by the rings themselves through the gap between the ring ends or through the insertion incision.3 Theoretically, induced astigmatism is partially prevented by symmetrical placement of the rings. Recently, ICRSs have been used to treat keratoconus and corneal ectasia after LASIK. For
Accepted for publication September 17, 2003. From W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA. The author has no financial or proprietary interest in any material or method mentioned. Reprint requests to Alan Sugar, MD, W.K. Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, 1000 Wall Street, Ann Arbor, Michigan 48105, USA. E-mail: [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
those purposes, the rings are usually placed horizontally with a thicker segment inferiorly and a thinner one superiorly to manage decentration and asymmetry of corneal astigmatism.4,5 Removal of ICRSs has been necessary in some patients with excessive symptoms of glare or halo or has been combined with an exchange to treat refractive overcorrection or undercorrection.6 A patient who had 1 ring segment removed for overcorrection is reported here.
Case Report Institutional review board approval and informed consent from the patient were obtained for this report. A 46-year-old woman presented to the center in September 1999 seeking decreased dependence on spectacles. The uncorrected visual acuity (UCVA) was 20/70 in each eye. Manifest and cycloplegic refractions were ⫺1.50 ⫹0.75 ⫻ 25 and ⫺1.75 ⫹0.75 ⫻ 164 for a visual acuity of 20/15– in both eyes. Near vision corrected well with a ⫹1.00 add. Slitlamp examination was normal. Central corneal thickness by ultrasound was 585 m in the right eye and 583 m in the left eye. Keratometry was 45.5 ⫻ 45.5 and 45.5 ⫻ 46.5@153, respectively. Topographies were normal. Refractive surgical options were discussed. The patient decided to proceed with ICRS insertion in the right eye only, allowing a trial period to maintain good uncorrected reading vision in the left eye. In October 1999, 2 0.25 mm Intacs 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2003.09.059
CASE REPORTS: SUGAR
Figure 1. (Sugar) Right eye 1 week after removal of the temporal ring segment.
rings were inserted uneventfully in the right eye through a superior incision with a 440 m depth. One week postoperatively, the UCVA was 20/30⫹ in the right eye; with a manifest refraction of ⫹1.50 sphere, the visual acuity was 20/20⫹. The ring segments were well
Figure 2. (Sugar) Orbscan elevation and power maps 5 months after removal of the temporal ring segment.
1128
centered and at about 60% depth. The patient complained of blurring in the right eye. The visual acuity remained unchanged over the following 6 months. Exchange of the 0.25 mm rings for 0.20 mm rings was discussed if the latter were approved by the U.S. Food and Drug Administration. Despite the trial period for spectacle correction, by August 2001, the patient could no longer tolerate the hyperopia and complained of temporal glare in the right eye. The manifest refraction was ⫹0.50 ⫹0.75 ⫻ 25. In November 2001, the temporal ring was removed under topical anesthesia using the technique described by Schanzlin et al.7 One week after the temporal ring was removed, the patient had no glare and the UCVA in the right eye was 20/20, correcting to 20/15 with plano ⫹0.50 ⫻ 35 (Figure 1). When the patient was examined in April 2002, the UCVA was 20/15 in the right eye and the manifest refraction was plano. The UCVA in the left eye was J1. Simulated keratometry was 44.1 ⫻ 44.9@78 in the right eye using Orbscan topography (Bausch & Lomb) (Figure 2).
Discussion Intacs are available in the U.S. in 5 thicknesses from 0.25 to 0.35 mm to correct –1.00 to –3.00 diopters of myopic spherical equivalent. With their semicircular configuration, they are not intended to correct astigmatism. Although added thickness does not occur in a complete circular arc of the corneal periphery, induced astigmatism has not been a major problem.3 The asymmetry of corneal thickness induced by the presence of a single ring segment might be expected to induce astigmatism in the meridian of the ring arc center or possibly in that hemimeridian alone. The astigmatism in the patient reported here was unchanged from preoperatively when both ring segments were present. After the removal of 1 segment, there was mild relative vertical steepening consistent with a small coupling effect of the horizontal flattening. Removal of ring pairs was reported in 8.70% of 449 eyes in the initial Intacs trials. The risk for removal was greatest for the thickest ring segments.6 The most frequent indications for removal were visual symptoms (51.00%) (eg, glare, halos, fluctuations, diplopia, and difficulty with night vision). Overcorrection or undercorrection was the indication for removal of 23.00% of segments. In many eyes, exchange of the ring segment for rings of different thicknesses corrects the ammetropia.8 In the patient reported here, the 0.25 mm ring segment would have been exchanged for a 0.20 mm segment if that size had been available.
J CATARACT REFRACT SURG—VOL 30, MAY 2004
CASE REPORTS: SUGAR
To my knowledge, details of single-ring removal have not been reported. Boxer Wachler9 mentions a single case but reports no specific data.9 Alio´ and coauthors10 report the removal of a single ring after using Intacs to treat post-LASIK ectasia but provide no details.10 Removal of 1 of 2 ring segments to decrease the refractive effect may be a reasonable alternative. If the effect is inadequate or visually significant astigmatism is induced, the second ring can be removed.
4.
5.
6.
7.
References 1. Rapuano CJ, Sugar A, Koch DD, et al. Intrastromal corneal ring segments for low myopia; a report of the American Academy of Ophthalmology. (Ophthalmic Technology Assessment) Ophthalmology 2001; 108: 1922–1928 2. Holmes-Higgin DK, Burris TE. Corneal surface topography and associated visual performance with INTACS for myopia; phase III clinical trial results; the INTACS Study Group. Ophthalmology 2000; 107:2061–2071 3. Twa MD, Ruckhofer J, Schanzlin DJ. Surgically induced astigmatism after implantation of Intacs intrastromal
8.
9.
10.
corneal ring segments. J Cataract Refract Surg 2001; 27: 411–415 Lovisolo CF, Fleming JF. Intracorneal ring segments for iatrogenic keratectasia after laser in situ keratomileusis or photorefractive keratectomy. J Refract Surg 2002; 18: 535–541 Siganos CS, Kymionis GD, Kartakis N, et al. Management of keratoconus with Intacs. Am J Ophthalmol 2003; 135:64–70 Clinch TE, Lemp MA, Foulks GN, Schanzlin DJ. Removal of INTACS for myopia. Ophthalmology 2002; 109: 1441–1446 Schanzlin DJ, Abbott RL, Asbell PA, et al. Two-year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmology 2001; 108:1688– 1694 ¨O ¨ , Durrie DS, Lindstrom RL. Asbell PA, Uc¸akhan O Adjustability of refractive effect for corneal ring segments. J Refract Surg 1999; 15:627–631 Boxer Wachler BS. Therapeutic uses of intracorneal corneal ring segments. Refractive Eyecare for Ophthalmologists, 2001; 5(12):12–16 Alio´ JL, Salem TF, Artola A, Osman AA. Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:1568–1574
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