- Email: [email protected]
Intraoperative retinoscopy: A way to achieve emmetropia in cataract surgery
CORRESPONDENCE
During the follow-up, no problem was seen in biomicroscopic and other examinations (Figure 3). The fluorescence noted in the anterior chamber disappeared by day 7 (Figure 4). While the mean UCVA was 0.5 (range 0.3 to 0.8), the mean BCVA was 0.9 (range 0.8 to 1.0) at the last examination. The IOP was within normal limits in all cases. In conclusion, we think that indocyanine green used in an appropriate concentration and for an appropriate period of time may be a good choice for staining the anterior capsule. MEHMET BAYKARA, MD REMZI AVCı, MD ALI YU¨CEL, MD ¨ ZC¸ETIN, MD HIKMET O Bursa, Turkey
References 1. Pandey SK, Werner L, Escobar-Gomez M, et al. Dyeenhanced cataract surgery. Part 1: anterior capsule staining for capsulorhexis in advanced/white cataract. J Cataract Refract Surg 2000; 26:1052–1059 2. Fritz WL. Fluorescein blue, light-assisted capsulorhexis for mature or hypermature cataract. J Cataract Refract Surg 1998; 24:19–20 3. Lee YC, Park CK, Kim MS, Kim JH. In vitro study for staining and toxicity of rose bengal on cultured bovine corneal endothelial cells. Cornea 1996; 15:376– 385 4. Melles GRJ, de Waard PTW, Pameyer JH, Beekhuis WH. Trypan blue capsule staining to visualize the capsulorhexis in cataract surgery. J Cataract Refract Surg 1999; 25:7–9 5. Holley GPJ, Alam A, Kiri A, Edelhauser HF. Effect of indocyanine green intraocular stain on human and rabbit corneal endothelial structure and viability: an in vitro study. J Cataract Refract Surg 2002; 28:1027– 1033
Intraoperative retinoscopy: A way to achieve emmetropia in cataract surgery
T
he problems that eye surgeons face in calculating intraocular lens (IOL) power in cataract surgery are well known. Most occur in patients in developing countries, where there is a lack of sophisticated instruments, an absence of clinical history, and patients with 1258
monocular or binocular mature cataract. In developed countries, despite advanced technology, incorrect IOL power is still implanted. The most common reason for implantation of the wrong IOL power is incorrect measurement of the eye’s axial length.1 Less common reasons include incorrect labeling of the IOL2 and handing the wrong IOL to surgeons by the assisting staff. In recent years, another problem has been patients (primarily myopic) who develop cataract after refractive surgery. In these patients, it is a rule that cataract surgeons use as many techniques as possible to calculate the IOL power. We describe 1 technique for doing this. As a result of thinking about the problem of incorrect IOL power and having a copy of Peter Choyce’s book on IOLs and implants,3 I realized that intraoperative retinoscopy had a role to play in calculating IOL power. At the time he wrote the book, Choyce was still inserting his anterior chamber IOLs as a secondary procedure in most cases. A stable manifest refraction (MR) was the criterion for reopening the eye. By performing retinoscopy in the aphakic eye in the first part of cataract surgery, primary IOL implantation is converted to a secondary one. Aphakia, that is, the aphakic stage of surgery after removal of the cataract, will be present until there is a way to prevent opacification of the crystalline lens. The second retinoscopy is performed in the pseudophakic eye to ensure the correct IOL power is implanted. Technique A sterile battery retinoscope and 2 sets of sterile trial lenses are prepared: C6.00 diopters (D) to C16.00 D for the first retinoscopy and ÿ5.00 to C5.00 D for the second retinoscopy. These lenses will be appropriate in most cases. I thought briefly about also using the sterile trial frame, but with the calculation of IOL power based on biometric measurements, I changed my mind. I was fortunate to have the IOL power based on the retinoscopic findings, close to the biometric ones, without the use of the trial frame. Phacoemulsification is performed through a corneal incision, followed by irrigation/aspiration. The first retinoscopy is performed after the posterior capsule is well cleaned, the iris flat, the pupil well dilated, and the depth of the anterior chamber about 4.00 mm. The
J CATARACT REFRACT SURG—VOL 31, JUNE 2005
CORRESPONDENCE
second retinoscopy is performed with the IOL well centered in the capsular bag and after the ophthalmic viscosurgical device has been replaced with a balanced salt solution. During the retinoscopies, the lights of the operating room are dimmed. To calculate the IOL power, I use as a base the accepted standard4: C10.00 D spherical equivalent (SE) in spectacle correction for the emmetropic eye after cataract extraction. I assume that an IOL of C19.00 D in the capsular bag makes the eye emmetropic. The empirical rule of thumb proposed by Kenneth Hoffer, MD, and James Gill, MD, is then used. For hyperopia, every diopter over C10.00 D is multiplied by 1.5 and the result is added to C19.00 D. For myopia, every diopter below C10.00 D is multiplied by 1.3 and the result is subtracted from C19.00 D. This calculation ensures measurements in the range of C8.50 to C14.00 D. Beyond this level, fourth- and fifth-generation IOL power calculation formulas are needed. Samuel Masket, MD, has reported that aphakic contact lens power equals the approximate power for the secondary anterior chamber IOL (S. Masket, MD, ‘‘IOL Calculation for Secondary Lens Implantation,’’ presented at the XIXth Congress of the European Society of Cataract & Refractive Surgeons,’’ Amsterdam, The Netherlands, September 2001). For the posterior chamber IOL, C2.00 D or C3.00 D must be added to the aphakic contact lens power. This calculation will be most helpful in straightforward cataract extraction, particularly in patients in developing countries. I applied the retinoscopic findings of the aphakic stage in a 75-year-old woman with early nuclear sclerosis in the right eye and moderate nuclear sclerosis in the left eye. She was a known hyperope with correction for an SE of C2.25 D in the right eye and C1.75 D in the left eye. I removed the cataract from the left eye and performed retinoscopy. The SE was C11.5 D, and a C21.00 D silicone IOL was implanted. The eye ended with a ÿ0.50 cylinder at 180 degrees. These were the findings from the second retinoscopy. The next day, the patient’s visual acuity was 20/20 with the above correction. Had I used the ‘‘ready-reckoning’’ method proposed by Henry Clayman, MD,5 the spherical error would have been an SE of C0.50 to C0.75 D. I have used the ‘‘ready-reckoning’’ method for many years and for eyes with an axial length of 21.50 to 25.00 mm.
Discussion Retinoscopy in the Aphakic Stage. The first retinoscopy can be applied in the following situations: (1) Patients in developing countries who need cataract extraction and in the absence of biometric measurements. It would be a pity to perform a good cataract extraction and, at the end of surgery, insert a standard C19.00 D IOL in an eye with moderate or high myopia or hyperopia. (2) Patients who need cataract extraction some years after refractive surgery. Hyperopia is a frequent outcome in these patients and is due to the incorrect corneal power measurements by instruments used today. Jaime Aramberri, MD, has concluded that the double-K method does not eliminate hyperopic results.6 Therefore, calculating IOL power in patients after refractive surgery remains a complex problem.7 The findings of the retinoscopy can be used in cases without clinical history, which is considered the gold standard, and in the presence of lens opacities, which preclude performing valid refraction. By freeing the path to the light entering the eye, the use of the contact lens method proposed by Hoffer8 is feasible. Retinoscopy in the Pseudophakic Eye. The purpose of performing the second retinoscopy in the pseudophakic eye is obvious. Not having to perform a second surgery in many cases will save time, money, and anxiety for patients and will protect the reputation of the surgeon. Incorrect IOL power is the most common reason for reoperating on an eye. Discovering at the end of the operation that an incorrect IOL power has been implanted will force the surgeon to do something on the spot—either replacing the IOL or implanting a second IOL in piggyback fashion. Having 1 IOL in the capsular bag is safer. Replacing the IOL at the end of the procedure is less risky than doing it a few months later. Finally, I can foresee 3 modifications to the technique: (1) The use of a sterile, plano, rigid contact lens (poly[methyl methacrylate]), as proposed by Hoffer, in patients after refractive surgery. (2) With knowledge of the IOL power in the pseudophakic eye, the axial length can be calculated from the refraction.9 In replacing the IOL, it is vital to measure the dioptric power of the removed IOL. (3) The use of a handheld autorefractor to perform the retinoscopy more quickly with more
J CATARACT REFRACT SURG—VOL 31, JUNE 2005
1259
CORRESPONDENCE
accurate measurements. Intraoperative retinoscopy slightly increases the time of surgery. COSTAS SARINAS, MD Athens, Greece
References 1. Craig EA, Hanna IT, McGilvray S, et al. Nurse or doctor: biometry for intraocular lens power calculation; who should measure? Health Bull 1995; 53:105–109 2. Olsen T, Olesen H. IOL power mislabeling. Acta Ophthalmol Scand 1993; 71:99–102 3. Choyce P. Intra-ocular Lenses and Implants. London, HK Lewis & Co Ltd, 1964 4. Duke-Elder WS. The Practice of Refraction, 9th ed. London, Churchill Livingstone, 1978 5. Clayman HM. The Surgeon’s Guide to Intraocular Lens Implantation. Thorofare, NJ, Slack, 1985 6. Aramberri J. Intraocular lens power calculation after corneal refractive surgery: double-K method. J Refract Surg 2003; 29:2063–2068 7. Koch D, Wang L. Calculating IOL power in eyes that have had refractive surgery. J Cataract Refract Surg 2003; 29: 2039–2042 8. Hoffer KJ. Calculating intraocular lens power after refractive corneal surgery. Arch Ophthalmol 2002; 120: 500–501 9. Olsen T. Calculating axial length in aphakic and the pseudophakic eye. J Cataract Refract Surg 1988; 14:413– 416
Intraoperative fracture of AMO Clariflex silicone posterior chamber IOL
A
73-year-old woman was admitted for right eye phacoemulsification with intraocular lens (IOL) implantation under local anesthesia. She had no previous eye problems. The AMO Clariflex silicone posterior chamber IOL was chosen for implantation. Routine phacoemulsification with IOL implantation was carried out by an experienced surgeon. The IOL injector (Allergan Unfolder model PSHST) was used to inject the IOL. A fracture in the IOL optic adjacent to the haptic (Figure 1) was noted after implantation. The IOL was not exchanged as the fracture was in the optic periphery and the IOL’s position in the capsular bag was satisfactory. The operation was otherwise uneventful.
1260
Figure 1. The photograph shows a fracture in the IOL optic adjacent to the haptic.
One day postoperatively, the patients’ visual acuity was 6/9 and examination of the eye was satisfactory. The subsequent follow-ups until 3 months postoperatively were satisfactory, with the uncorrected visual acuity of 6/9, improving to 6/6 with spectacle correction. The patient remained asymptomatic and pleased with the visual improvement. Discussion The Clariflex model CLRFLXB silicone posterior chamber IOL is available with a biconvex optic with the square OptiEdge design. It is intended to be implanted in the ciliary sulcus or capsular bag following extracapsular cataract extraction or phacoemulsification. The optic has the ability to be folded before insertion, allowing the IOL to be inserted through an incision of 3.0 mm. Fracture of implanted anterior chamber and posterior chamber poly(methyl methacrylate) IOLs has been reported.1–5 To our knowledge, this is the first report of an intraoperative fracture of a silicone Clariflex IOL since its introduction. The cause of the fracture in this case could be the shearing force applied to the IOL as it worked its way out of the injector. The injector was checked and found to have no defect. Before implantation, there was no obvious sign of a preexisting IOL imperfection microscopically. From this case, it is clear that under certain circumstances, the optic of the Clariflex IOL can fracture and appropriate care should be taken when using an
J CATARACT REFRACT SURG—VOL 31, JUNE 2005
During the follow-up, no problem was seen in biomicroscopic and other examinations (Figure 3). The fluorescence noted in the anterior chamber disappeared by day 7 (Figure 4). While the mean UCVA was 0.5 (range 0.3 to 0.8), the mean BCVA was 0.9 (range 0.8 to 1.0) at the last examination. The IOP was within normal limits in all cases. In conclusion, we think that indocyanine green used in an appropriate concentration and for an appropriate period of time may be a good choice for staining the anterior capsule. MEHMET BAYKARA, MD REMZI AVCı, MD ALI YU¨CEL, MD ¨ ZC¸ETIN, MD HIKMET O Bursa, Turkey
References 1. Pandey SK, Werner L, Escobar-Gomez M, et al. Dyeenhanced cataract surgery. Part 1: anterior capsule staining for capsulorhexis in advanced/white cataract. J Cataract Refract Surg 2000; 26:1052–1059 2. Fritz WL. Fluorescein blue, light-assisted capsulorhexis for mature or hypermature cataract. J Cataract Refract Surg 1998; 24:19–20 3. Lee YC, Park CK, Kim MS, Kim JH. In vitro study for staining and toxicity of rose bengal on cultured bovine corneal endothelial cells. Cornea 1996; 15:376– 385 4. Melles GRJ, de Waard PTW, Pameyer JH, Beekhuis WH. Trypan blue capsule staining to visualize the capsulorhexis in cataract surgery. J Cataract Refract Surg 1999; 25:7–9 5. Holley GPJ, Alam A, Kiri A, Edelhauser HF. Effect of indocyanine green intraocular stain on human and rabbit corneal endothelial structure and viability: an in vitro study. J Cataract Refract Surg 2002; 28:1027– 1033
Intraoperative retinoscopy: A way to achieve emmetropia in cataract surgery
T
he problems that eye surgeons face in calculating intraocular lens (IOL) power in cataract surgery are well known. Most occur in patients in developing countries, where there is a lack of sophisticated instruments, an absence of clinical history, and patients with 1258
monocular or binocular mature cataract. In developed countries, despite advanced technology, incorrect IOL power is still implanted. The most common reason for implantation of the wrong IOL power is incorrect measurement of the eye’s axial length.1 Less common reasons include incorrect labeling of the IOL2 and handing the wrong IOL to surgeons by the assisting staff. In recent years, another problem has been patients (primarily myopic) who develop cataract after refractive surgery. In these patients, it is a rule that cataract surgeons use as many techniques as possible to calculate the IOL power. We describe 1 technique for doing this. As a result of thinking about the problem of incorrect IOL power and having a copy of Peter Choyce’s book on IOLs and implants,3 I realized that intraoperative retinoscopy had a role to play in calculating IOL power. At the time he wrote the book, Choyce was still inserting his anterior chamber IOLs as a secondary procedure in most cases. A stable manifest refraction (MR) was the criterion for reopening the eye. By performing retinoscopy in the aphakic eye in the first part of cataract surgery, primary IOL implantation is converted to a secondary one. Aphakia, that is, the aphakic stage of surgery after removal of the cataract, will be present until there is a way to prevent opacification of the crystalline lens. The second retinoscopy is performed in the pseudophakic eye to ensure the correct IOL power is implanted. Technique A sterile battery retinoscope and 2 sets of sterile trial lenses are prepared: C6.00 diopters (D) to C16.00 D for the first retinoscopy and ÿ5.00 to C5.00 D for the second retinoscopy. These lenses will be appropriate in most cases. I thought briefly about also using the sterile trial frame, but with the calculation of IOL power based on biometric measurements, I changed my mind. I was fortunate to have the IOL power based on the retinoscopic findings, close to the biometric ones, without the use of the trial frame. Phacoemulsification is performed through a corneal incision, followed by irrigation/aspiration. The first retinoscopy is performed after the posterior capsule is well cleaned, the iris flat, the pupil well dilated, and the depth of the anterior chamber about 4.00 mm. The
J CATARACT REFRACT SURG—VOL 31, JUNE 2005
CORRESPONDENCE
second retinoscopy is performed with the IOL well centered in the capsular bag and after the ophthalmic viscosurgical device has been replaced with a balanced salt solution. During the retinoscopies, the lights of the operating room are dimmed. To calculate the IOL power, I use as a base the accepted standard4: C10.00 D spherical equivalent (SE) in spectacle correction for the emmetropic eye after cataract extraction. I assume that an IOL of C19.00 D in the capsular bag makes the eye emmetropic. The empirical rule of thumb proposed by Kenneth Hoffer, MD, and James Gill, MD, is then used. For hyperopia, every diopter over C10.00 D is multiplied by 1.5 and the result is added to C19.00 D. For myopia, every diopter below C10.00 D is multiplied by 1.3 and the result is subtracted from C19.00 D. This calculation ensures measurements in the range of C8.50 to C14.00 D. Beyond this level, fourth- and fifth-generation IOL power calculation formulas are needed. Samuel Masket, MD, has reported that aphakic contact lens power equals the approximate power for the secondary anterior chamber IOL (S. Masket, MD, ‘‘IOL Calculation for Secondary Lens Implantation,’’ presented at the XIXth Congress of the European Society of Cataract & Refractive Surgeons,’’ Amsterdam, The Netherlands, September 2001). For the posterior chamber IOL, C2.00 D or C3.00 D must be added to the aphakic contact lens power. This calculation will be most helpful in straightforward cataract extraction, particularly in patients in developing countries. I applied the retinoscopic findings of the aphakic stage in a 75-year-old woman with early nuclear sclerosis in the right eye and moderate nuclear sclerosis in the left eye. She was a known hyperope with correction for an SE of C2.25 D in the right eye and C1.75 D in the left eye. I removed the cataract from the left eye and performed retinoscopy. The SE was C11.5 D, and a C21.00 D silicone IOL was implanted. The eye ended with a ÿ0.50 cylinder at 180 degrees. These were the findings from the second retinoscopy. The next day, the patient’s visual acuity was 20/20 with the above correction. Had I used the ‘‘ready-reckoning’’ method proposed by Henry Clayman, MD,5 the spherical error would have been an SE of C0.50 to C0.75 D. I have used the ‘‘ready-reckoning’’ method for many years and for eyes with an axial length of 21.50 to 25.00 mm.
Discussion Retinoscopy in the Aphakic Stage. The first retinoscopy can be applied in the following situations: (1) Patients in developing countries who need cataract extraction and in the absence of biometric measurements. It would be a pity to perform a good cataract extraction and, at the end of surgery, insert a standard C19.00 D IOL in an eye with moderate or high myopia or hyperopia. (2) Patients who need cataract extraction some years after refractive surgery. Hyperopia is a frequent outcome in these patients and is due to the incorrect corneal power measurements by instruments used today. Jaime Aramberri, MD, has concluded that the double-K method does not eliminate hyperopic results.6 Therefore, calculating IOL power in patients after refractive surgery remains a complex problem.7 The findings of the retinoscopy can be used in cases without clinical history, which is considered the gold standard, and in the presence of lens opacities, which preclude performing valid refraction. By freeing the path to the light entering the eye, the use of the contact lens method proposed by Hoffer8 is feasible. Retinoscopy in the Pseudophakic Eye. The purpose of performing the second retinoscopy in the pseudophakic eye is obvious. Not having to perform a second surgery in many cases will save time, money, and anxiety for patients and will protect the reputation of the surgeon. Incorrect IOL power is the most common reason for reoperating on an eye. Discovering at the end of the operation that an incorrect IOL power has been implanted will force the surgeon to do something on the spot—either replacing the IOL or implanting a second IOL in piggyback fashion. Having 1 IOL in the capsular bag is safer. Replacing the IOL at the end of the procedure is less risky than doing it a few months later. Finally, I can foresee 3 modifications to the technique: (1) The use of a sterile, plano, rigid contact lens (poly[methyl methacrylate]), as proposed by Hoffer, in patients after refractive surgery. (2) With knowledge of the IOL power in the pseudophakic eye, the axial length can be calculated from the refraction.9 In replacing the IOL, it is vital to measure the dioptric power of the removed IOL. (3) The use of a handheld autorefractor to perform the retinoscopy more quickly with more
J CATARACT REFRACT SURG—VOL 31, JUNE 2005
1259
CORRESPONDENCE
accurate measurements. Intraoperative retinoscopy slightly increases the time of surgery. COSTAS SARINAS, MD Athens, Greece
References 1. Craig EA, Hanna IT, McGilvray S, et al. Nurse or doctor: biometry for intraocular lens power calculation; who should measure? Health Bull 1995; 53:105–109 2. Olsen T, Olesen H. IOL power mislabeling. Acta Ophthalmol Scand 1993; 71:99–102 3. Choyce P. Intra-ocular Lenses and Implants. London, HK Lewis & Co Ltd, 1964 4. Duke-Elder WS. The Practice of Refraction, 9th ed. London, Churchill Livingstone, 1978 5. Clayman HM. The Surgeon’s Guide to Intraocular Lens Implantation. Thorofare, NJ, Slack, 1985 6. Aramberri J. Intraocular lens power calculation after corneal refractive surgery: double-K method. J Refract Surg 2003; 29:2063–2068 7. Koch D, Wang L. Calculating IOL power in eyes that have had refractive surgery. J Cataract Refract Surg 2003; 29: 2039–2042 8. Hoffer KJ. Calculating intraocular lens power after refractive corneal surgery. Arch Ophthalmol 2002; 120: 500–501 9. Olsen T. Calculating axial length in aphakic and the pseudophakic eye. J Cataract Refract Surg 1988; 14:413– 416
Intraoperative fracture of AMO Clariflex silicone posterior chamber IOL
A
73-year-old woman was admitted for right eye phacoemulsification with intraocular lens (IOL) implantation under local anesthesia. She had no previous eye problems. The AMO Clariflex silicone posterior chamber IOL was chosen for implantation. Routine phacoemulsification with IOL implantation was carried out by an experienced surgeon. The IOL injector (Allergan Unfolder model PSHST) was used to inject the IOL. A fracture in the IOL optic adjacent to the haptic (Figure 1) was noted after implantation. The IOL was not exchanged as the fracture was in the optic periphery and the IOL’s position in the capsular bag was satisfactory. The operation was otherwise uneventful.
1260
Figure 1. The photograph shows a fracture in the IOL optic adjacent to the haptic.
One day postoperatively, the patients’ visual acuity was 6/9 and examination of the eye was satisfactory. The subsequent follow-ups until 3 months postoperatively were satisfactory, with the uncorrected visual acuity of 6/9, improving to 6/6 with spectacle correction. The patient remained asymptomatic and pleased with the visual improvement. Discussion The Clariflex model CLRFLXB silicone posterior chamber IOL is available with a biconvex optic with the square OptiEdge design. It is intended to be implanted in the ciliary sulcus or capsular bag following extracapsular cataract extraction or phacoemulsification. The optic has the ability to be folded before insertion, allowing the IOL to be inserted through an incision of 3.0 mm. Fracture of implanted anterior chamber and posterior chamber poly(methyl methacrylate) IOLs has been reported.1–5 To our knowledge, this is the first report of an intraoperative fracture of a silicone Clariflex IOL since its introduction. The cause of the fracture in this case could be the shearing force applied to the IOL as it worked its way out of the injector. The injector was checked and found to have no defect. Before implantation, there was no obvious sign of a preexisting IOL imperfection microscopically. From this case, it is clear that under certain circumstances, the optic of the Clariflex IOL can fracture and appropriate care should be taken when using an
J CATARACT REFRACT SURG—VOL 31, JUNE 2005