Refractive challenges and innovations A toric challenge: Surgeons review a complicated case
Refractive challenges and innovations
A toric challenge: Surgeons review a complicated case
--------------------------------------------------------------------------------
Figure 1
Figure 2
From selection to insertion, toric lenses may present challenges to the best of surgeons. EyeWorld presented a complicated toric case from Kerry D. Solomon, M.D., EyeWorld refractive editor, and director, Carolina Eyecare Research Institute, Carolina Eyecare Physicians, Charleston, S.C., and asked surgeons to comment on how they would handle it.
A 77-year-old man complained of worsening vision, trouble with glare and haloes, and difficulty driving at night after having toric lenses implanted. Pre-op, his manifest refraction (MRx) was –0.50 +0.50 x 15 in the right eye and –2.00 +2.00 x 165 in the left. Slit lamp evaluation on both eyes was given a score of 2+ with nuclear sclerotic and cortical changes. Corneal topography, corneal measurements, and surgical plan for the left eye are shown (Figures 1 and 2).
Three weeks post-op, the patient complained that he would like his visual acuity (UCVA: 20/40; MRx: –0.75 +1.25 x 180; toric IOL@144
degrees) to be better.
"This case artfully illustrates some of the commonly occurring challenges facing the refractive cataract surgeon today, despite the availability of an impressive suite of new technologies aimed at offering extreme precision," said Neel R. Desai, M.D., Largo, Fla. "These challenges snowball from the pre-operative biometry and IOL selection onward to intraoperative alignment of the toric IOL and ultimately manifest in a curious post-operative refractive surprise."
Dr. Desai and John P. Berdahl, M.D., Sioux Falls, S.D., shared their thoughts.
After looking over the case, what would you do next?
Dr. Desai: To begin, the biometry is rather inconsistent and misleading with regard to the true magnitude and axis of astigmatism. The available topography, in this particular case, reveals considerable asymmetry and irregularity that often corresponds to pre-existing ocular surface disease, such as Salzmann's nodular degeneration. Other cases of seemingly irregular astigmatism may be a result of dry eye syndrome, eccentric scans, prolonged (rigid) contact lens wear, or more easily identified keratoectatic disorders. Radial keratotomy may also generate irregular patterns of astigmatism that are difficult to compensate for with conventional techniques like LRI or toric IOLs. When presented with similar challenging cases of misleading pre-operative biometry, I am frequently saved by the availability of the WaveTec ORA (WaveTec Vision, Aliso Viejo, Calif.) intraoperative wavefront aberrometry. The real-time aphakic and pseudophakic refractive data provided can allow intraoperative optimization of IOL power selection and alignment that takes into account the patient's central visual axis, angle kappa, and surgically induced astigmatism (SIA). In this case, the ORA may have led us to select a T5 Toric (Alcon, Fort Worth, Texas), with 3.0 D of correction in the IOL plane and 2.06 D of correction in the spectacle plane, from our consignment of toric IOLs. Furthermore, the ORA system may have helped fine-tune IOL orientation to the true axis of cylinder, taking into account supine cyclotorsion, SIA, and other easily overlooked factors like mild lens tilt. Dr. Berdahl: My next step would be a careful slit lamp evaluation looking specifically for ocular surface disease and subtle ABMD. Provided OSD was minimal and there was no ABMD, I would then visit astigmatismfix.com (soon to be on the ASCRS IOL calculation site) to determine if the toric IOL was not placed in the ideal axis. The ideal axis is not always the same as the intended axis. Based on Dr. Solomon's manual keratometry and toric IOL calculation from the Alcon AcrySof Toric calculation site, the IOL was placed in the intended axis, but factors like posterior corneal curvature and unanticipated surgically induced astigmatism can cause the ideal axis and intended axis to be different. After entering the manifest refraction and current location and power of the toric IOL, the website will calculate the amount of IOL rotation and the anticipated residual astigmatism. If the residual astigmatism after IOL rotation is significant, either an IOL exchange or an excimer photoablation would be more appropriate. In this case, the expected post-rotation refraction would be –0.54 +0.82 x 163, which would decrease the astigmatism by about 0.5 D but would leave over 0.75 D of astigmatism. Given the difficulty this patient is having, I suspect he would not be satisfied with >0.75 D residual astigmatism, and I would lean toward an excimer laser photoablation.
What are some of the biggest challenges in treating a case like this?
Dr. Desai: Post-operative management of this patient is just as challenging as identifying the source of the refractive surprise itself. With the option of referring such patients to the expert hands of Dr. Solomon not always available to me, I might consider the option of performing an early IOL exchange with ORA confirmation versus laser vision correction with LASIK or PRK. Despite the widespread, and often justified, reluctance to perform an IOL exchange, I believe we should not take this option off the table if it is the most likely to address the problem where it exists. For those uncomfortable with the possibility of opening a Pandora's box of new problems via attempted IOL exchange, PRK enhancement might offer the safest and easiest route to 20/happy. I generally prefer PRK enhancement over LASIK in post-cataract cases because of this patient population's propensity for dry eye syndrome, basement membrane dystrophy, and other disorders that may complicate LASIK flap healing. Dr. Berdahl: One challenge is to match the intended axis with the ideal axis. Recently Doug Koch, M.D., has taught us that the against-the-rule astigmatism increases as patients age because of changes to the posterior corneal curvature. Importantly, posterior corneal curvature is not measured in keratometry measurements. This phenomenon will generally lead to an undercorrection of against-the-rule astigmatism (which happened in this case) or an overcorrection of with-the-rule astigmatism.
Can you offer pearls for similar cases?
Dr. Desai: • Recognize irregular astigmatism in pre-operative biometry.
• Identify the source of irregularity (e.g., bad scan, ocular surface disease) and treat it appropriately before repeating biometry or performing cataract surgery.
• Try to quantify the treatable regular astigmatism in the central 3 mm zone, paying particular attention to the central flattest and steepest Ks.
• Know your SIA and account for it. • Optimize IOL selection and orientation by marking patients pre-operatively in a seated position and utilizing the real-time refractive data provided by ORA.
• Identify refractive surprises and their source quickly and develop a plan. Don't forget to let the patient know.
• Be sure to distinguish toric IOL power issues from problems stemming from orientation of the toric IOL. • Consider IOL exchange early when it's easiest and least prone to complication. • Don't be afraid to tell a patient aiming for 20/10 that the "enemy of good is perfect" and that the safest thing to do is nothing. Dr. Berdahl: • Carefully check for dryness and ABMD pre- and post-operatively.
• If ABMD is present, do PRK instead of LASIK.
• Understand when to rotate the IOL, exchange the IOL, or perform excimer photoablation.
• The most accurate way to rotate the IOL to the new position is to use the current location as a reference point and rotate the IOL the proper amount from the reference point, i.e., in this case rotate it 24 degrees counterclockwise from the current location, as opposed to marking the cornea at 170 degrees and rotating it to that position. This mitigates cyclotorsion errors.
Dr. Solomon: In this case, the corneal surface does not reveal any evidence of basement membrane changes, degenerative changes/nodules, or evidence of any pathology. While the astigmatism is asymmetric, it is not irregular and lines up repeatedly along a distinct axis. It is not unusual to find different devices measure the corneal curve with different techniques and slightly different areas of the cornea. In this case, this patient was satisfied with his previous vision prior to the development of cataracts with glasses. He is not a contact lens wearer (and his vision did not improve pre-op with a hard contact lens over-refraction). Given his pre-op history of good vision with spectacles and his motivation to be less dependent on corrective eyewear for distance, it seems reasonable to consider a toric IOL. In closely looking at his pre-op corneal measurements, his manual keratometry and topography measurements (drawing a line through the steep axis) lined up quite well. Hence, 153 degrees was used in the toric calculator. Taking into account the surgically induced astigmatism from the clear corneal incision for his cataract surgery, the toric calculator indicated his toric IOL (T3, Alcon) should be oriented at 144 degrees. Post-operatively, his residual astigmatism (+1.25 diopters) was oriented at 15 degrees. This post-op refraction, while unexpected, is part of the art and science of refractive cataract surgery. As Dr. Berdahl suggested, the posterior corneal surface, as recently pointed out by Dr. Koch, may play a more integral role in some patients more than others. Options that I considered for this patient are: LASIK or PRK enhancement versus IOL exchange with use of intraoperative aberrometry (ORA) to fine-tune the refractive outcome versus IOL repositioning. In this case, the website developed by Dr. Berdahl and David Hardten, M.D. (astigmatismfix.com), indicated that rotating the current toric IOL 149 degrees clockwise to a final resting position of 175 degrees should leave the patient with a residual refractive error of –0.33 + 0.42 axis 168 and a spherical equivalent of –.12 diopters. This was quite acceptable to me. A second surgery was performed and the currently implanted toric IOL was rotated to the axis of 175 degrees. Intraoperative aberrometry with ORA confirmed minimal residual refractive error. One month post-operatively, the patient had an uncorrected vision of 20/20 with a refraction of –0.25 + 0.25 axis 110. The patient is extremely happy with his result and pleased that I was willing to do whatever it took to fix the problem. Residual uncorrected refractive error is one of the most common reasons for an unhappy patient following refractive surgery or refractive cataract surgery. In my experience, patients are more disappointed if a physician is not receptive to their concerns and not willing to commit to their issues. In this case, the patient's uncorrected vision was 20/40 and BCVA was 20/20 (improved from a pre-op BCVA of 20/50). In some ways, one could make the argument that he "should be happy." In being willing to listen to the patient's concerns and understanding his desire to be less dependent on glasses, we took a potentially unhappy patient and converted him to an extremely happy and satisfied patient. In fact, this patient was never afforded the opportunity to become unhappy. I identified with his concerns immediately and presented options (including glasses) for a solution. The patient was not upset that he did not reach his refractive target the first time around, was understanding that medicine and science is not perfect, and was grateful for my suggestions and ultimate solution to his problem.
Editors' note: Dr. Berdahl has financial interests with Alcon, Allergan (Irvine, Calif.), and ISTA Pharmaceuticals (Irvine, Calif.). Dr. Desai has financial interests with Alcon, Allergan, Bausch + Lomb (Rochester, N.Y.), Bio-Tissue (Miami, Fla.), Inspire Pharmaceuticals (Raleigh, N.C.), WaveTec Vision, and TruVision (Santa Barbara, Calif.). Dr. Solomon has financial interests with Abbott Medical Optics (Santa Ana, Calif.) and Alcon.
Contact information
Berdahl: 605-328-3937, johnberdahl@gmail.com
Desai: 727-518-2020, desaivision@hotmail.com
Solomon: kerry.solomon@carolinaeyecare.com
A toric challenge: Surgeons review a complicated case
--------------------------------------------------------------------------------
by Jena Passut EyeWorld Editor
Figure 1
Figure 2
From selection to insertion, toric lenses may present challenges to the best of surgeons. EyeWorld presented a complicated toric case from Kerry D. Solomon, M.D., EyeWorld refractive editor, and director, Carolina Eyecare Research Institute, Carolina Eyecare Physicians, Charleston, S.C., and asked surgeons to comment on how they would handle it.
A 77-year-old man complained of worsening vision, trouble with glare and haloes, and difficulty driving at night after having toric lenses implanted. Pre-op, his manifest refraction (MRx) was –0.50 +0.50 x 15 in the right eye and –2.00 +2.00 x 165 in the left. Slit lamp evaluation on both eyes was given a score of 2+ with nuclear sclerotic and cortical changes. Corneal topography, corneal measurements, and surgical plan for the left eye are shown (Figures 1 and 2).
Three weeks post-op, the patient complained that he would like his visual acuity (UCVA: 20/40; MRx: –0.75 +1.25 x 180; toric IOL@144
degrees) to be better.
"This case artfully illustrates some of the commonly occurring challenges facing the refractive cataract surgeon today, despite the availability of an impressive suite of new technologies aimed at offering extreme precision," said Neel R. Desai, M.D., Largo, Fla. "These challenges snowball from the pre-operative biometry and IOL selection onward to intraoperative alignment of the toric IOL and ultimately manifest in a curious post-operative refractive surprise."
Dr. Desai and John P. Berdahl, M.D., Sioux Falls, S.D., shared their thoughts.
After looking over the case, what would you do next?
Dr. Desai: To begin, the biometry is rather inconsistent and misleading with regard to the true magnitude and axis of astigmatism. The available topography, in this particular case, reveals considerable asymmetry and irregularity that often corresponds to pre-existing ocular surface disease, such as Salzmann's nodular degeneration. Other cases of seemingly irregular astigmatism may be a result of dry eye syndrome, eccentric scans, prolonged (rigid) contact lens wear, or more easily identified keratoectatic disorders. Radial keratotomy may also generate irregular patterns of astigmatism that are difficult to compensate for with conventional techniques like LRI or toric IOLs. When presented with similar challenging cases of misleading pre-operative biometry, I am frequently saved by the availability of the WaveTec ORA (WaveTec Vision, Aliso Viejo, Calif.) intraoperative wavefront aberrometry. The real-time aphakic and pseudophakic refractive data provided can allow intraoperative optimization of IOL power selection and alignment that takes into account the patient's central visual axis, angle kappa, and surgically induced astigmatism (SIA). In this case, the ORA may have led us to select a T5 Toric (Alcon, Fort Worth, Texas), with 3.0 D of correction in the IOL plane and 2.06 D of correction in the spectacle plane, from our consignment of toric IOLs. Furthermore, the ORA system may have helped fine-tune IOL orientation to the true axis of cylinder, taking into account supine cyclotorsion, SIA, and other easily overlooked factors like mild lens tilt. Dr. Berdahl: My next step would be a careful slit lamp evaluation looking specifically for ocular surface disease and subtle ABMD. Provided OSD was minimal and there was no ABMD, I would then visit astigmatismfix.com (soon to be on the ASCRS IOL calculation site) to determine if the toric IOL was not placed in the ideal axis. The ideal axis is not always the same as the intended axis. Based on Dr. Solomon's manual keratometry and toric IOL calculation from the Alcon AcrySof Toric calculation site, the IOL was placed in the intended axis, but factors like posterior corneal curvature and unanticipated surgically induced astigmatism can cause the ideal axis and intended axis to be different. After entering the manifest refraction and current location and power of the toric IOL, the website will calculate the amount of IOL rotation and the anticipated residual astigmatism. If the residual astigmatism after IOL rotation is significant, either an IOL exchange or an excimer photoablation would be more appropriate. In this case, the expected post-rotation refraction would be –0.54 +0.82 x 163, which would decrease the astigmatism by about 0.5 D but would leave over 0.75 D of astigmatism. Given the difficulty this patient is having, I suspect he would not be satisfied with >0.75 D residual astigmatism, and I would lean toward an excimer laser photoablation.
What are some of the biggest challenges in treating a case like this?
Dr. Desai: Post-operative management of this patient is just as challenging as identifying the source of the refractive surprise itself. With the option of referring such patients to the expert hands of Dr. Solomon not always available to me, I might consider the option of performing an early IOL exchange with ORA confirmation versus laser vision correction with LASIK or PRK. Despite the widespread, and often justified, reluctance to perform an IOL exchange, I believe we should not take this option off the table if it is the most likely to address the problem where it exists. For those uncomfortable with the possibility of opening a Pandora's box of new problems via attempted IOL exchange, PRK enhancement might offer the safest and easiest route to 20/happy. I generally prefer PRK enhancement over LASIK in post-cataract cases because of this patient population's propensity for dry eye syndrome, basement membrane dystrophy, and other disorders that may complicate LASIK flap healing. Dr. Berdahl: One challenge is to match the intended axis with the ideal axis. Recently Doug Koch, M.D., has taught us that the against-the-rule astigmatism increases as patients age because of changes to the posterior corneal curvature. Importantly, posterior corneal curvature is not measured in keratometry measurements. This phenomenon will generally lead to an undercorrection of against-the-rule astigmatism (which happened in this case) or an overcorrection of with-the-rule astigmatism.
Can you offer pearls for similar cases?
Dr. Desai: • Recognize irregular astigmatism in pre-operative biometry.
• Identify the source of irregularity (e.g., bad scan, ocular surface disease) and treat it appropriately before repeating biometry or performing cataract surgery.
• Try to quantify the treatable regular astigmatism in the central 3 mm zone, paying particular attention to the central flattest and steepest Ks.
• Know your SIA and account for it. • Optimize IOL selection and orientation by marking patients pre-operatively in a seated position and utilizing the real-time refractive data provided by ORA.
• Identify refractive surprises and their source quickly and develop a plan. Don't forget to let the patient know.
• Be sure to distinguish toric IOL power issues from problems stemming from orientation of the toric IOL. • Consider IOL exchange early when it's easiest and least prone to complication. • Don't be afraid to tell a patient aiming for 20/10 that the "enemy of good is perfect" and that the safest thing to do is nothing. Dr. Berdahl: • Carefully check for dryness and ABMD pre- and post-operatively.
• If ABMD is present, do PRK instead of LASIK.
• Understand when to rotate the IOL, exchange the IOL, or perform excimer photoablation.
• The most accurate way to rotate the IOL to the new position is to use the current location as a reference point and rotate the IOL the proper amount from the reference point, i.e., in this case rotate it 24 degrees counterclockwise from the current location, as opposed to marking the cornea at 170 degrees and rotating it to that position. This mitigates cyclotorsion errors.
Dr. Solomon: In this case, the corneal surface does not reveal any evidence of basement membrane changes, degenerative changes/nodules, or evidence of any pathology. While the astigmatism is asymmetric, it is not irregular and lines up repeatedly along a distinct axis. It is not unusual to find different devices measure the corneal curve with different techniques and slightly different areas of the cornea. In this case, this patient was satisfied with his previous vision prior to the development of cataracts with glasses. He is not a contact lens wearer (and his vision did not improve pre-op with a hard contact lens over-refraction). Given his pre-op history of good vision with spectacles and his motivation to be less dependent on corrective eyewear for distance, it seems reasonable to consider a toric IOL. In closely looking at his pre-op corneal measurements, his manual keratometry and topography measurements (drawing a line through the steep axis) lined up quite well. Hence, 153 degrees was used in the toric calculator. Taking into account the surgically induced astigmatism from the clear corneal incision for his cataract surgery, the toric calculator indicated his toric IOL (T3, Alcon) should be oriented at 144 degrees. Post-operatively, his residual astigmatism (+1.25 diopters) was oriented at 15 degrees. This post-op refraction, while unexpected, is part of the art and science of refractive cataract surgery. As Dr. Berdahl suggested, the posterior corneal surface, as recently pointed out by Dr. Koch, may play a more integral role in some patients more than others. Options that I considered for this patient are: LASIK or PRK enhancement versus IOL exchange with use of intraoperative aberrometry (ORA) to fine-tune the refractive outcome versus IOL repositioning. In this case, the website developed by Dr. Berdahl and David Hardten, M.D. (astigmatismfix.com), indicated that rotating the current toric IOL 149 degrees clockwise to a final resting position of 175 degrees should leave the patient with a residual refractive error of –0.33 + 0.42 axis 168 and a spherical equivalent of –.12 diopters. This was quite acceptable to me. A second surgery was performed and the currently implanted toric IOL was rotated to the axis of 175 degrees. Intraoperative aberrometry with ORA confirmed minimal residual refractive error. One month post-operatively, the patient had an uncorrected vision of 20/20 with a refraction of –0.25 + 0.25 axis 110. The patient is extremely happy with his result and pleased that I was willing to do whatever it took to fix the problem. Residual uncorrected refractive error is one of the most common reasons for an unhappy patient following refractive surgery or refractive cataract surgery. In my experience, patients are more disappointed if a physician is not receptive to their concerns and not willing to commit to their issues. In this case, the patient's uncorrected vision was 20/40 and BCVA was 20/20 (improved from a pre-op BCVA of 20/50). In some ways, one could make the argument that he "should be happy." In being willing to listen to the patient's concerns and understanding his desire to be less dependent on glasses, we took a potentially unhappy patient and converted him to an extremely happy and satisfied patient. In fact, this patient was never afforded the opportunity to become unhappy. I identified with his concerns immediately and presented options (including glasses) for a solution. The patient was not upset that he did not reach his refractive target the first time around, was understanding that medicine and science is not perfect, and was grateful for my suggestions and ultimate solution to his problem.
Editors' note: Dr. Berdahl has financial interests with Alcon, Allergan (Irvine, Calif.), and ISTA Pharmaceuticals (Irvine, Calif.). Dr. Desai has financial interests with Alcon, Allergan, Bausch + Lomb (Rochester, N.Y.), Bio-Tissue (Miami, Fla.), Inspire Pharmaceuticals (Raleigh, N.C.), WaveTec Vision, and TruVision (Santa Barbara, Calif.). Dr. Solomon has financial interests with Abbott Medical Optics (Santa Ana, Calif.) and Alcon.
Contact information
Berdahl: 605-328-3937, johnberdahl@gmail.com
Desai: 727-518-2020, desaivision@hotmail.com
Solomon: kerry.solomon@carolinaeyecare.com
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