- Email: [email protected]
Imaging scleral expansion bands for presbyopia with optical coherence tomography
Imaging scleral expansion bands for presbyopia with optical coherence tomography Christopher Wirbelauer, MD, Amir Karandish, MD, Henning Aurich, MD, Duy Thoai Pham, MD A 57-year-old woman was treated for mild presbyopia with implantation of scleral expansion bands (SEB). Although near vision was temporarily restored, the effect dissipated after 1 year. Slitlamp-adapted optical coherence tomography (OCT) at 1310 nm allowed precise cross-sectional visualization of the hyporeflective intrascleral segments. The OCT method provided precise images of the segment depth and thickness, the scleral thickness at the scleral spur, the anterior chamber angle, and the angle-opening distance. Intrascleral tilting of 1 segment was seen; this required removal of the SEB because of marked foreign-body sensation. Noncontact, slitlamp-adapted OCT can be used to evaluate scleral changes after SEB implantation. J Cataract Refract Surg 2003; 29:2435–2438 2003 ASCRS and ESCRS
T
he surgical correction of presbyopia caused by a loss of accommodative amplitude is being evaluated. Recently, implantation of scleral expansion bands (SEB) has been proposed for the reversal of presbyopia.1,2 Placing poly(methyl methacrylate) (PMMA) segments within the sclera in the region of the ciliary body has been shown to restore accommodation in some patients by increasing the distance between the ciliary muscle and the equator of the lens. According to an alternative theory of the mechanism of accommodation, this improves zonular tension by ciliary muscle contraction and a temporary increase in the amplitude of accommodation.1 Although this mechanism is controversial,3–5 it provides an interesting surgical approach for the correction of presbyopia. Furthermore, recent clinical evidence
Accepted for publication February 3, 2003. From the Klinik fu¨r Augenheilkunde, Vivantes Klinikum Neuko¨lln, Berlin, Germany. None of the authors has a proprietary or financial interest in any product mentioned. Supported in part by the Herbert Funke-Stiftung, Berlin, Germany. Reprint requests to Christopher Wirbelauer, MD, Klinik fu¨r Augenheilkunde, Vivantes Klinikum Neuko¨lln, Rudower Strasse 48, D-12351 Berlin, Germany. E-mail: [email protected]. 2003 ASCRS and ESCRS Published by Elsevier Inc.
suggests that the SEB procedure might decrease intraocular pressure. Optical coherence tomography (OCT) offers the ability to objectively monitor changes in anterior segment structures in a noncontact mode. In previous clinical evaluations,6–8 we demonstrated that slitlampadapted OCT enables cross-sectional and high-resolution imaging of the cornea. In this report, we used slitlamp-adapted OCT to evaluate the scleral position and depth of the implanted PMMA segments in a patient who had bilateral SEB implantation.
Case Report A 57-year-old woman was treated bilaterally with SEB for mild presbyopia. In the right eye, the refractive error (RE) with an autorefractometer was ⫹0.25 –0.50 ⫻ 148 with an uncorrected visual acuity (UCVA) of 1.0 (decimal fraction). In the left eye, the RE was ⫹1.00 –0.75 ⫻ 128 with a UCVA of 1.0. The addition for near vision was ⫹1.50 diopters (D) in the right eye and ⫹0.75 D in the left eye. The patient had no history of ocular trauma, ocular inflammation, or systemic disease. Scleral expansion band implantation was performed under topical anesthesia using Schachar’s standard technique in the presence of an instructor from Schachar’s team (Presbycorp).5 The implanted curved segments were made of PMMA with a width of 1380 m, a thickness of 925 m, and a length of 5.5 mm with rounded smooth 0886-3350/03/$–see front matter doi:10.1016/j.jcrs.2003.02.001
CASE REPORTS: WIRBELAUER
edges and small furrows on the posterior side. Although the patient perceived temporary improvement in reading vision without glasses, this effect dissipated at 1 year with the need for an addition of ⫹1.0 D in both eyes. Furthermore, she complained of a foreign-body sensation and occasional redness in the right eye unresponsive to topical lubricant therapy. This was caused by significant tilt of 1 segment, which was removed after 1 year without complications. In no other segment was rotation or displacement observed. All 8 segments were examined in the scleral and anteriorchamber-angle regions in both eyes after 1 year with slitlampadapted OCT (Anterior Segment OCT, 4Optics AG). To enhance the OCT image of the anterior eye segment, a light source using a superluminescent diode (SLD-561, Superlum) operating at a wavelength of 1310 nm with a bandwidth of 50 nm and incident-light intensity less than 200W was used. The sample arm of the interferometer and the scanning module were integrated in the projected slit of a standard clinical slitlamp (SL-3C, Topcon), as described.6–9 For the tomographic representation, the reflected light was analyzed and the intensity was converted to logarithmic gray-scale images, which were simultaneously recorded during the measurements. Slitlamp-adapted OCT enabled determination of all thicknesses using the axial interference profile of the reflections. The high detection sensitivity was used to manually measure the distance between the optical signals, with the highest reflectivity at the tissue boundaries. The optical delay values obtained were then divided by the refractive index of the sclera (n ⫽ 1.33) to obtain the geometric distances between the tissue interfaces. The SEB segment thickness was converted using the index of refraction of PMMA (n ⫽ 1.475) for wavelength 1310 nm at 20⬚C. The following parameters were measured: anterior depth and central thickness of the segments, distance from the posterior side of the segments to the ciliary body region, scleral thickness at the optical scleral spur, anterior chamber angle, and angle-opening distance. In 1 segment with intrascleral tilting, the longitudinal position was also assessed. Several optical sections were taken and the mean and SD of these measurements processed. All results are presented as means ⫾ SD and range.
Figure 1. (Wirbelauer) A: Representative clinical photograph of an SEB (arrow). B: Horizontal slitlamp-adapted OCT (gray scale) after SEB implantation with visualization of the hyporeflective PMMA segment. C: Longitudinal slitlamp-adapted OCT (gray scale) after SEB implantation. Note the small furrows on the posterior side (arrow).
Results With slitlamp-adapted OCT, the SEB segments revealed marked hyporeflective intrascleral changes in all sections; these correlated with macroscopic findings (Figures 1 and 2). Cross-sectional imaging with slitlamp-adapted OCT allowed determination of the precise position of the hyporeflective PMMA segments because of displacement of the collagen fibers in the sclera (Figure 1). In the right eye, the anterior border of the segment in the midsection was measured at a 2436
mean axial depth from the anterior surface of 344 ⫾ 38 m superotemporally, 416 ⫾ 24 m superonasally, 332 ⫾ 35 m inferotemporally, and 293 ⫾ 14 m inferonasally. In the left eye, the anterior depth was 253 ⫾ 29 m, 420 ⫾ 2 m, 192 ⫾ 35 m, and 423 ⫾ 17 m, respectively. The segment in the superotemporal quadrant of the right eye showed marked intrascleral tilting, with longitudinal anterior depth values ranging from 250 to 1315 m (Figure 2, C). After this segment
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003
CASE REPORTS: WIRBELAUER
Figure 3. (Wirbelauer) Slitlamp-adapted OCT showing the SEB (asterisk), the hyporeflective ciliary body region (arrow), and the anterior chamber angle (ACA). Note the proximity of the SEB to the ciliary body region.
was explanted, a thin hyporeflective scleral zone was noted in the implantation area (Figure 2, D). The mean optically measured thickness of the SEB segments was 867 ⫾ 39 m (range 750 to 933 m). The mean scleral thickness at the optical scleral spur was 831 ⫾ 84 m (range 751 to 952 m) in the right eye and 791 ⫾ 38 m (range 741 to 952 m) in the left eye. The mean anterior chamber angle was 38 ⫾ 1.6 degrees and 34 ⫾ 1.4 degrees, respectively. The mean angle-opening distance was 585 ⫾ 78 m in the right eye and 576 ⫾ 33 m in the left eye. In Figure 3, the proximity of the intrascleral segment to the hyporeflective ciliary body region and the anterior chamber angle structures can be observed. The mean axial distance from the posterior border of the SEB to the ciliary body region was 1330 ⫾ 169 m (range 1123 to 1511 m).
Discussion
Figure 2. (Wirbelauer) A: Clinical photograph of a tilted SEB producing a foreign-body sensation (arrow, superficial end; asterisk, deep end). B: Horizontal slitlamp-adapted OCT (gray scale) of the SEB in A. C: Longitudinal slitlamp-adapted OCT (gray scale) of the same SEB with imaging of marked tilting. The anterior border of the segment is at variable depths ranging from 250 to 1315 m. D: Slitlamp-adapted OCT after explantation of the SEB in A. Only a thin hyporeflective scleral zone in the implant area can be seen (arrow).
Surgical correction of presbyopia, which is the most common refractive error, is being evaluated. Although the scleral mechanism of restoring accommodation is not fully understood and several studies indicate that physiologic dynamic accommodation cannot be restored by scleral expansion procedures,3–5 biometric data about the exact position and depth of the scleral implants and incisions or ablation depth in laser-assisted scleral surgery are important in assessing the refractive effects of nonlenticular restoration of accommodation. Optical coherence tomography is a high-resolution technology that can create precise cross-sectional images of the anterior segment and cornea.6–8 The particular
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003
2437
CASE REPORTS: WIRBELAUER
advantage of the slitlamp-adapted OCT is the 2-dimensional graphic representation of light reflected and backscattered from ocular tissue structures, allowing thickness measurements without contact. In our case, OCT allowed quantitative evaluation of the intrascleral changes and provided valuable information about the implanted SEB. At a wavelength of 1310 nm, this instrument provided better scleral visualization than retinal OCT, which uses a wavelength of approximately 830 nm. Imaging was similar to OCT of intracorneal ring segments for the correction of mild myopia9; a hyporeflective PMMA segment placed intrasclerally was clearly visible. Our results confirm that slitlamp-adapted OCT can be used to measure scleral thickness before implantation and control the depth of SEB implantation, which could be critical to the refractive effect. In this patient, we noted a wide variation in anterior depth of the SEB, ranging from 192 to 423 m. The mean geometric thickness of the SEB was 867 m, which was slightly less than the manufacturer’s thickness of 925 m. Slitlampadapted OCT can also be used to evaluate postoperative changes in the SEB position to quantitate possible segment tilting, as noted in 1 segment with an anterior longitudinal depth of more than 1315 m at the deepest end. As demonstrated in this patient, OCT enables estimation of the distance from the SEB to the hyporeflective ciliary body region and objective determination of changes in the anterior chamber angle region.
2438
In summary, this case demonstrated that slitlampadapted OCT system provides a noncontact, cross-sectional, and high-resolution representation of the scleral configuration after SEB implantation. There is strong evidence that slitlamp-adapted OCT at 1310 nm enables noninvasive assessment of SEB implantation or similar evolving scleral procedures.
References 1. Schachar RA. Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation. Ann Ophthalmol 1992; 24:445–447; 452 2. Schachar RA. Is Helmholtz’s theory of accommodation correct? Ann Ophthalmol 1999; 31:10–17 3. Glasser A, Kaufman PL. The mechanism of accommodation in primates. Ophthalmology 1999; 106:863–872 4. Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia. Ophthalmology 1999; 106:873–877 5. Malecaze FJ, Gazagne CS, Tarroux MC, Gorrand J-M. Scleral expansion bands for presbyopia. Ophthalmology 2001; 108:2165–2171 6. Wirbelauer C, Scholz C, Hoerauf H, et al. Corneal optical coherence tomography before and immediately after excimer laser photorefractive keratectomy. Am J Ophthalmol 2000; 130:693–699 7. Wirbelauer C, Scholz C, Hoerauf H, et al. Untersuchungen der Hornhaut mittels optischer Koha¨renztomographie. Ophthalmologe 2001; 98:151–156 8. Wirbelauer C, Scholz C, Hoerauf H, et al. Noncontact corneal pachymetry with slit lamp-adapted optical coherence tomography. Am J Ophthalmol 2002; 133:444–450 9. Wirbelauer C, Winkler J, Scholz C, et al. Experimental imaging of intracorneal ring segments with optical coherence tomography. J Refract Surg 2003; 19:367–371
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003
T
he surgical correction of presbyopia caused by a loss of accommodative amplitude is being evaluated. Recently, implantation of scleral expansion bands (SEB) has been proposed for the reversal of presbyopia.1,2 Placing poly(methyl methacrylate) (PMMA) segments within the sclera in the region of the ciliary body has been shown to restore accommodation in some patients by increasing the distance between the ciliary muscle and the equator of the lens. According to an alternative theory of the mechanism of accommodation, this improves zonular tension by ciliary muscle contraction and a temporary increase in the amplitude of accommodation.1 Although this mechanism is controversial,3–5 it provides an interesting surgical approach for the correction of presbyopia. Furthermore, recent clinical evidence
Accepted for publication February 3, 2003. From the Klinik fu¨r Augenheilkunde, Vivantes Klinikum Neuko¨lln, Berlin, Germany. None of the authors has a proprietary or financial interest in any product mentioned. Supported in part by the Herbert Funke-Stiftung, Berlin, Germany. Reprint requests to Christopher Wirbelauer, MD, Klinik fu¨r Augenheilkunde, Vivantes Klinikum Neuko¨lln, Rudower Strasse 48, D-12351 Berlin, Germany. E-mail: [email protected]. 2003 ASCRS and ESCRS Published by Elsevier Inc.
suggests that the SEB procedure might decrease intraocular pressure. Optical coherence tomography (OCT) offers the ability to objectively monitor changes in anterior segment structures in a noncontact mode. In previous clinical evaluations,6–8 we demonstrated that slitlampadapted OCT enables cross-sectional and high-resolution imaging of the cornea. In this report, we used slitlamp-adapted OCT to evaluate the scleral position and depth of the implanted PMMA segments in a patient who had bilateral SEB implantation.
Case Report A 57-year-old woman was treated bilaterally with SEB for mild presbyopia. In the right eye, the refractive error (RE) with an autorefractometer was ⫹0.25 –0.50 ⫻ 148 with an uncorrected visual acuity (UCVA) of 1.0 (decimal fraction). In the left eye, the RE was ⫹1.00 –0.75 ⫻ 128 with a UCVA of 1.0. The addition for near vision was ⫹1.50 diopters (D) in the right eye and ⫹0.75 D in the left eye. The patient had no history of ocular trauma, ocular inflammation, or systemic disease. Scleral expansion band implantation was performed under topical anesthesia using Schachar’s standard technique in the presence of an instructor from Schachar’s team (Presbycorp).5 The implanted curved segments were made of PMMA with a width of 1380 m, a thickness of 925 m, and a length of 5.5 mm with rounded smooth 0886-3350/03/$–see front matter doi:10.1016/j.jcrs.2003.02.001
CASE REPORTS: WIRBELAUER
edges and small furrows on the posterior side. Although the patient perceived temporary improvement in reading vision without glasses, this effect dissipated at 1 year with the need for an addition of ⫹1.0 D in both eyes. Furthermore, she complained of a foreign-body sensation and occasional redness in the right eye unresponsive to topical lubricant therapy. This was caused by significant tilt of 1 segment, which was removed after 1 year without complications. In no other segment was rotation or displacement observed. All 8 segments were examined in the scleral and anteriorchamber-angle regions in both eyes after 1 year with slitlampadapted OCT (Anterior Segment OCT, 4Optics AG). To enhance the OCT image of the anterior eye segment, a light source using a superluminescent diode (SLD-561, Superlum) operating at a wavelength of 1310 nm with a bandwidth of 50 nm and incident-light intensity less than 200W was used. The sample arm of the interferometer and the scanning module were integrated in the projected slit of a standard clinical slitlamp (SL-3C, Topcon), as described.6–9 For the tomographic representation, the reflected light was analyzed and the intensity was converted to logarithmic gray-scale images, which were simultaneously recorded during the measurements. Slitlamp-adapted OCT enabled determination of all thicknesses using the axial interference profile of the reflections. The high detection sensitivity was used to manually measure the distance between the optical signals, with the highest reflectivity at the tissue boundaries. The optical delay values obtained were then divided by the refractive index of the sclera (n ⫽ 1.33) to obtain the geometric distances between the tissue interfaces. The SEB segment thickness was converted using the index of refraction of PMMA (n ⫽ 1.475) for wavelength 1310 nm at 20⬚C. The following parameters were measured: anterior depth and central thickness of the segments, distance from the posterior side of the segments to the ciliary body region, scleral thickness at the optical scleral spur, anterior chamber angle, and angle-opening distance. In 1 segment with intrascleral tilting, the longitudinal position was also assessed. Several optical sections were taken and the mean and SD of these measurements processed. All results are presented as means ⫾ SD and range.
Figure 1. (Wirbelauer) A: Representative clinical photograph of an SEB (arrow). B: Horizontal slitlamp-adapted OCT (gray scale) after SEB implantation with visualization of the hyporeflective PMMA segment. C: Longitudinal slitlamp-adapted OCT (gray scale) after SEB implantation. Note the small furrows on the posterior side (arrow).
Results With slitlamp-adapted OCT, the SEB segments revealed marked hyporeflective intrascleral changes in all sections; these correlated with macroscopic findings (Figures 1 and 2). Cross-sectional imaging with slitlamp-adapted OCT allowed determination of the precise position of the hyporeflective PMMA segments because of displacement of the collagen fibers in the sclera (Figure 1). In the right eye, the anterior border of the segment in the midsection was measured at a 2436
mean axial depth from the anterior surface of 344 ⫾ 38 m superotemporally, 416 ⫾ 24 m superonasally, 332 ⫾ 35 m inferotemporally, and 293 ⫾ 14 m inferonasally. In the left eye, the anterior depth was 253 ⫾ 29 m, 420 ⫾ 2 m, 192 ⫾ 35 m, and 423 ⫾ 17 m, respectively. The segment in the superotemporal quadrant of the right eye showed marked intrascleral tilting, with longitudinal anterior depth values ranging from 250 to 1315 m (Figure 2, C). After this segment
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003
CASE REPORTS: WIRBELAUER
Figure 3. (Wirbelauer) Slitlamp-adapted OCT showing the SEB (asterisk), the hyporeflective ciliary body region (arrow), and the anterior chamber angle (ACA). Note the proximity of the SEB to the ciliary body region.
was explanted, a thin hyporeflective scleral zone was noted in the implantation area (Figure 2, D). The mean optically measured thickness of the SEB segments was 867 ⫾ 39 m (range 750 to 933 m). The mean scleral thickness at the optical scleral spur was 831 ⫾ 84 m (range 751 to 952 m) in the right eye and 791 ⫾ 38 m (range 741 to 952 m) in the left eye. The mean anterior chamber angle was 38 ⫾ 1.6 degrees and 34 ⫾ 1.4 degrees, respectively. The mean angle-opening distance was 585 ⫾ 78 m in the right eye and 576 ⫾ 33 m in the left eye. In Figure 3, the proximity of the intrascleral segment to the hyporeflective ciliary body region and the anterior chamber angle structures can be observed. The mean axial distance from the posterior border of the SEB to the ciliary body region was 1330 ⫾ 169 m (range 1123 to 1511 m).
Discussion
Figure 2. (Wirbelauer) A: Clinical photograph of a tilted SEB producing a foreign-body sensation (arrow, superficial end; asterisk, deep end). B: Horizontal slitlamp-adapted OCT (gray scale) of the SEB in A. C: Longitudinal slitlamp-adapted OCT (gray scale) of the same SEB with imaging of marked tilting. The anterior border of the segment is at variable depths ranging from 250 to 1315 m. D: Slitlamp-adapted OCT after explantation of the SEB in A. Only a thin hyporeflective scleral zone in the implant area can be seen (arrow).
Surgical correction of presbyopia, which is the most common refractive error, is being evaluated. Although the scleral mechanism of restoring accommodation is not fully understood and several studies indicate that physiologic dynamic accommodation cannot be restored by scleral expansion procedures,3–5 biometric data about the exact position and depth of the scleral implants and incisions or ablation depth in laser-assisted scleral surgery are important in assessing the refractive effects of nonlenticular restoration of accommodation. Optical coherence tomography is a high-resolution technology that can create precise cross-sectional images of the anterior segment and cornea.6–8 The particular
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003
2437
CASE REPORTS: WIRBELAUER
advantage of the slitlamp-adapted OCT is the 2-dimensional graphic representation of light reflected and backscattered from ocular tissue structures, allowing thickness measurements without contact. In our case, OCT allowed quantitative evaluation of the intrascleral changes and provided valuable information about the implanted SEB. At a wavelength of 1310 nm, this instrument provided better scleral visualization than retinal OCT, which uses a wavelength of approximately 830 nm. Imaging was similar to OCT of intracorneal ring segments for the correction of mild myopia9; a hyporeflective PMMA segment placed intrasclerally was clearly visible. Our results confirm that slitlamp-adapted OCT can be used to measure scleral thickness before implantation and control the depth of SEB implantation, which could be critical to the refractive effect. In this patient, we noted a wide variation in anterior depth of the SEB, ranging from 192 to 423 m. The mean geometric thickness of the SEB was 867 m, which was slightly less than the manufacturer’s thickness of 925 m. Slitlampadapted OCT can also be used to evaluate postoperative changes in the SEB position to quantitate possible segment tilting, as noted in 1 segment with an anterior longitudinal depth of more than 1315 m at the deepest end. As demonstrated in this patient, OCT enables estimation of the distance from the SEB to the hyporeflective ciliary body region and objective determination of changes in the anterior chamber angle region.
2438
In summary, this case demonstrated that slitlampadapted OCT system provides a noncontact, cross-sectional, and high-resolution representation of the scleral configuration after SEB implantation. There is strong evidence that slitlamp-adapted OCT at 1310 nm enables noninvasive assessment of SEB implantation or similar evolving scleral procedures.
References 1. Schachar RA. Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation. Ann Ophthalmol 1992; 24:445–447; 452 2. Schachar RA. Is Helmholtz’s theory of accommodation correct? Ann Ophthalmol 1999; 31:10–17 3. Glasser A, Kaufman PL. The mechanism of accommodation in primates. Ophthalmology 1999; 106:863–872 4. Mathews S. Scleral expansion surgery does not restore accommodation in human presbyopia. Ophthalmology 1999; 106:873–877 5. Malecaze FJ, Gazagne CS, Tarroux MC, Gorrand J-M. Scleral expansion bands for presbyopia. Ophthalmology 2001; 108:2165–2171 6. Wirbelauer C, Scholz C, Hoerauf H, et al. Corneal optical coherence tomography before and immediately after excimer laser photorefractive keratectomy. Am J Ophthalmol 2000; 130:693–699 7. Wirbelauer C, Scholz C, Hoerauf H, et al. Untersuchungen der Hornhaut mittels optischer Koha¨renztomographie. Ophthalmologe 2001; 98:151–156 8. Wirbelauer C, Scholz C, Hoerauf H, et al. Noncontact corneal pachymetry with slit lamp-adapted optical coherence tomography. Am J Ophthalmol 2002; 133:444–450 9. Wirbelauer C, Winkler J, Scholz C, et al. Experimental imaging of intracorneal ring segments with optical coherence tomography. J Refract Surg 2003; 19:367–371
J CATARACT REFRACT SURG—VOL 29, DECEMBER 2003