Complicated Cases IOL implantation in patients at high risk for retinal detachment by Omar F. Almallah? MD; Warren E. Hill, MD; John S. Jarstad, MD; Joel K. Shugar, MD; and J. Trevor Woodhams, MD
Reporting the case
I have been asked to review a chart by the defense attorneys in a case involving the following situation: A one-eyed 40-year-old patient developed retinopathy of prematurity (ROP) with a scleral buckle/band and a history of retinal detachment (RD) 25 years ago. The patient was referred for cataract surgery and had a silicone intraocular lens inserted? with subsequent decentering and RD. A silicone IOL was used despite the referring physician specifically requesting PMMA. Fortunately? the patient did well after IOL exchange with a PMMA IOL and retina repair.
The following are some questions from the legal complaint. Is it outside of the standard of care to use a silicone IOL instead of a PMMA or acrylic IOL in a patient prone to RD where silicone oil might later be necessary? Is it necessary to review records of past treating physicians or is knowledge of what was done from asking the patient and/or the referring physician adequate? It is well-known that cataract surgery can increase the risk of RD? but what about after a scleral buckle/ band has been implanted? J. Trevor Woodhams? MD
Atlanta
Understanding the circumstances
It is obviously better in hindsight to have used a PMMA or acrylic IOL? but physicians are still implanting silicone IOLs today. It is the standard of care to implant silicone IOLs in high myopes who are more prone to requiring buckles and silicone oil following routine cataract surgery.
It is also absolutely essential to review past records. Was this a small eye? Were intraoperative factors present that would have made PMMA or acrylic IOL placement less than optimal?
After a scleral buckle/band? the likelihood of a detachment would be less? so would this justify less concern for future detachment? In a difficult? one-eyed patient surgery? most physicians will go with their best operation? such as a foldable IOL silicone small incision.
It's always easy to "judge" another surgeon's work after the fact? particularly without adequate information. "You had to be there" in many cases to fully appreciate what went on and the reason for operative choices. While we attempt to use PMMA or acrylic IOLs in every diabetic patient with iritis or potential retina disaster? I can think of several exceptions during the past few years where silicone was placed without any adverse sequelae. John S. Jarstad? MD Seattle
Silicone oil also changes refraction with PMMA IOLs
With a prior retinal detachment, properly repaired, and with the retinal periphery still adequately supported, the chance of a subsequent retinal detachment following cataract surgery is relatively low. The fact that one recurred 25 years later is unfortunate, but not something that should generally be anticipated, even in an eye with ROP. I do not believe the placement of a silicone IOL is below the standard of care for this patient.
There are two points that make this a weak complaint by the plaintiff's attorney: IOL power and IOL design. Even if a biconvex PMMA lens had been used for the original cataract surgery, the postop refraction would be greatly altered in the presence of silicone oil. A +20-D biconvex PMMA intraocular lens would lose between a third and half of its refractive power in the presence of silicone oil.
If this surgeon had the power of clairvoyance (not yet a mandated level of care), and used a convex-plano PMMA lens with the plano side facing backwards the result would be a significant amount of postoperative hyperopia, usually between +3 D and +3.5 D.
If the surgeon used a typical biconvex PMMA lens, the individual shape factor of the lens then becomes important and determining the necessary power is more involved. A standard IOL calculation would result in an even higher degree of post-operative hyperopia in the presence of silicone oil, somewhere between +8 and +9.50 D. The modification of an existing scleral buckle makes the final post-operative refractive error even more problematic.
So, even if a PMMA lens had been placed at the time of cataract surgery, unless it was in the form of the less commonly used convex-plano design, and with an anticipated correction for silicone oil, the postop refraction would be significantly hyperopic. Any way you slice it, the IOL power would be incorrect as long as the silicone oil was in place. Warren E. Hill? MD Mesa? Ariz.
Plate designs lower RD risk
If a plate lens was used? the work of J. Stuart Cumming? MD? of Anaheim? Calif.? clearly showed that plates maintain vitreous volume better than any looped lens design? thus theoretically posing a lower risk of subsequent RD. Thus? in an eye with a prior RD or at risk for RD? a plate-haptic design could pose advantages in maintaining vitreous volume. Of course? the IOL material poses a problem with vitreoretinal surgery only if the capsule is open.
Joel K. Shugar? MD
Perry? Fla.
Silicone plate IOL may be the best choice
There are many retina specialists who have no objection to silicone IOLs in patients who may be at higher risk for RD. Furthermore? if a silicone plate was properly placed? there are ultrasonography studies that show that there is less forward movement of the posterior capsule after healing and fibrosis of the capsular bag with the silicone plate than with all other three-piece or conventional haptic IOLs. The risk, therefore, of posterior vitreous detachment? retinal traction? tear? and RD may be less as well. A silicone plate may be the best choice for an IOL in any patient who is at higher risk for RD.
I also believe the risks of RD are reduced after a scleral buckle/band is placed.
The following is a discussion from the archives of EyeMail? an ASCRS e-mail listserv. All ASCRS members can participate in EyeMail by contacting ASCRS/ASOA at ascrs@ascrs.org.
J.Trevor Woodhams, MD: "Is it outside of the standard of care to use a silicone IOL instead of a PMMA or acrylic IOL in a patient prone to RD where silicone oil might later be necessary?"
John S. Jarstad, MD: "It is the standard of care to implant silicone IOLs in high myopes who are more prone to requiring buckles and silicone oil following routine cataract surgery."
Warren E. Hill, MD: "Any way you slice it, the IOL power would be incorrect as long as the silicone oil was in place."
Joel K. Shugar, MD: "In an eye with a prior RD or at risk for RD? a plate-haptic design could pose advantages in maintaining vitreous volume."
Omar F. Almallah, MD: "There are many retina specialists who have no objection to silicone IOLs in patients who may be at higher risk for RD."
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