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Up Front | Jun 2003

Cataract Challenge

Unilateral Cataract With History of Trauma

A 34-year-old white male contact lens wearer presented for cataract evaluation. He stated that the vision in his right eye had been gradually decreasing and that he had noted a significant degree of glare with that eye. His past ocular history was significant for a blunt injury during a hockey game to his right eye 5 years earlier. This trauma resulted in a loss of vision lasting 4 days.

The patient's BCVA was 20/30 OD, glaring down to 20/100, and 20/25 OS, with no change on glare testing. The examination revealed significant posterior capsular opacification of the right lens and a clear left lens. I ob-served no phacodonesis. The posterior segment examination was noted for bilateral posterior vitreous detachments. The patient's pupils were equal and reactive to light, and no afferent pupil defect or anisocoria was evident. His IOP was 16 mm Hg OD and 12 mm Hg OS.

The patient's manifest refractions were -17.25 + 1.00 X 100 OD and -11.25 + 1.25 X 135 OS. His keratometry measurements were 41.00/42.00 D OD and 41.00/42.00 D OS. Contact A-scan biometry measured axial lengths of 31.37 mm OD and 28.99 mm OS. I found the patient's anterior chamber depths to be 3.68 mm OD and 3.18 mm OS. Using an IOLMaster (Carl Zeiss Meditec Inc., Dublin, CA), I found the patient's axial lengths to be 31.95 mm OD and 29.90 mm OS, and his keratometry readings were 41.36/ 42.78 @ 95 OD and 40.81/41.93 @ 120 OS.

The patient requested cataract surgery for his right eye.
1. Would you defer cataract surgery until the patient's left eye developed a cataract?
2. Plan cataract surgery with a highly myopic outcome so as to balance the degree of myopia?
3. Choose to follow cataract extraction by implanting an IOL that will render the patient's right eye emmetropic?
4. Perform cataract surgery and implant a multifocal lens?

After discussing the patient's IOL options, he expressed a preference for a multifocal lens. After administering topical anesthesia, I created a stepped, 1.5-mm limbal incision in the superotemporal quadrant of the patient's right eye. I then made a second paracentesis at the 2-o'clock position. Healon5 (Pfizer Inc., New York, NY) was injected through the supertemporal site into the anterior chamber. After creating an anterior capsulorhexis, I hydrodissected and hydrodelineated the lens using 1% unpreserved lidocaine.

Phacoemulsification by means of the Sovereign System with WhiteStar Technology (Advanced Medical Optics, Inc., Santa Ana, CA) removed the nucleus at aspiration settings of 24 mL/min unoccluded and 16 mL/min occluded, linear vacuum of 200 mm Hg with a threshold of 50 mm Hg, and a linear power of 15% unoccluded and 10% occluded. I employed cold phacoemulsification and bimanual instrumentation.

During surgery, I noticed two clock hours of zonular dehiscence in the eye's inferonasal region. I suspected it was due to the patient's previous blunt injury. During phacoemulsification, an injection of Healon5 posteriorly displaced the vitreous prolapsing through this region.

After cortical clean-up and posterior capsular polishing, I used Healon5 to maintain the anterior chamber. I im-planted an Array multifocal lens (Advanced Medical Optics, Inc.) in the capsular bag and placed a Staar AQ5010V lens (STAAR Surgical Company, Monrovia, CA) in the sulcus as a piggyback (Figure 1). After removing the viscoelastic, I could detect continued vitreous prolapse through the zonular dehiscence, so I performed an anterior vitrectomy. At the end of the operation, both lenses were centered and stable (Figure 2).

On the first postoperative day, the patient's operated eye had uncorrected distance vision of 20/20 and uncorrected near vision of J2. At the last visit, 6 weeks postoperatively, the patient had maintained this vision. He continues to wear a contact lens on his unoperated eye. The patient is highly satisfied with his outcome and has inquired about clear lens extraction with the implantation of an Array lens in his left eye.

This case illustrates the challenge of operating on a unilateral cataract in a high myope. Although deferring surgery might have been an option in the past, most ophthalmologists would now advocate extraction of a symptomatic cataract causing decreased vision.

Traditional surgical options leave a patient such as this one either aphakic or pseudophakic with a monofocal IOL. Aphakia was a viable alternative in this case, because the IOL calculation predicted an outcome of 0.50 to 2.50 D of hyperopia (depending on whether the contact biometry or IOLMaster were used). A contact lens could have easily managed this refractive error in an individual already accustomed to lens wear, but an aphakic individual is prone to vitreous instability if the capsular bag is left empty.

I considered implanting a monofocal IOL. Achieving an outcome with a balanced degree of myopia is possible, but it fails to achieve the benefits of refractive cataract surgery. I also presented to the patient the option of monofocal lens implantation with an em-metropic outcome.

However, because he was prepresbyopic, he related that he was reluctant to have presbyopia thrust upon him, albeit in one eye only.

It has been shown that stereovision, distance visual acuity, and near visual acuity are better in unilateral Array patients as compared with unilateral monofocal patients after unilateral cataract surgery.1 In this patient, the IOL calculation using the IOLMaster data determined that a plano Array lens would provide a postoperative refraction of +0.31 D, a result that would have been optimal for him. The minimal power for an Array lens is +6.00 D, however, so I considered implantation of a piggyback lens.

Piggyback IOL implantation with an Array lens has been described for high hyperopia with excellent results,2 but I found no information in the literature about a myopic piggyback lens implantation.

In this case, implanting a 6.00-D Array lens would have resulted in a predicted outcome of -3.73 D.

With an axial length of greater than 27 mm, the piggyback calculation ([1.3 X refractive error] -1.00) predicted that an IOL power for the Staar AQ5010V of -4.80 D would be necessary. The maximum negative power for this lens is -4.00 D. Therefore, I selected the Staar lens and anticipated a slightly myopic postoperative result.

This case demonstrates the viability of piggyback implantation with an Array multifocal lens in a high myope for unilateral cataract.
George Beiko, BM, BCh, FRCSC, is in private practice at St. Catharines in Ontario, Canada. He holds no financial interest in any product or technology described herein. This article describes an off-label use of the Array IOL. Dr. Beiko may be reached at (905) 687-8322; george.beiko@sympatico.ca.
1. Jacobi PC, Dietlein TS, Luke C, Jacobi FK. Multifocal intraocular lens implantation in prepresbyopic patients with unilateral cataract. Ophthalmology. 2002;109:680-686.
2. Donoso R, Rodriguez A. Piggyback implantation using the AMO Array multifocal intraocular lens. J Cataract Refract Surg. 2001;27:1506-1510.
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