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Up Front | May 2003

Refractive Challenge

Clear Lensectomy for High Hyperopia

To view the tables and figures related to this article, please refer to the print version of our May issue, page 44.

CASE PRESENTATION
A 17-year-old Hispanic male presented with preoperative refractive errors of +15.00 -1.75 X 5 = 20/50 OD and +15.25 -0.50 X 55 = 20/50 OS. He was contact lens intolerant and absolutely refused to wear his essentially aphakic spectacles for both cosmetic and functional reasons. He had an UCVA of 10/200 in each eye and obviously found performing his everyday activities to be extremely difficult. The patient's slit lamp examination, tonometry, and fundus examination were all normal. His keratometry readings were 48.25/49.00 OD and 48.00/48.50 OS, and his axial length measurements with an immersion technique were 16.19 mm OD and 16.11 mm OS. The patient's white-to-white corneal diameter was 11 mm in both eyes, and his anterior chamber depth was 3.4 mm OU. I was very concerned about his extremely short axial length, which indicated that his eyes were nanophthalmic.

HOW WOULD YOU PROCEED?
1. Would you discourage the patient from undergoing any corrective eye surgery and instead either fit him with glasses or encourage him to reattempt contact lens wear?
2. Recommend a phakic implant such as the STAAR ICL (STAAR Surgical Company, Monrovia, CA) with the understanding that this lens will not be available for at least 2 years unless the patient can be enrolled in an FDA study?
3. Choose to perform clear lensectomies, possibly with piggyback lenses due to the patient's degree of hyperopia?

SURGICAL COURSE
I believe that highly hyperopic patients are even more disabled visually than high myopes because, without their correction in place, they experience extreme blurring of both distance and near vision. Unfortunately, the surgical options for high hyperopes are more limited because LASIK and PRK have an upper limit of 5.00 to 6.00 D. Their procedural choices only include clear lensectomy and phakic intraocular implants, and phakic IOLs may be implanted in the US exclusively as part of an FDA study.

In the 1990 edition of the Video Journal of Ophthalmology, Cincinnati surgeon Robert Osher first suggested clear lensectomy for highly hyperopic patients. After reading reports of encouraging results,1,2 I performed my first clear lens extraction in a hyperopic patient who had developed a small, central corneal ulcer as a complication of extended-wear contact lenses. I later reported on the results of a series of hyperopic patients, including some who required piggyback IOLs because lens powers of greater than 30.00 D were unavailable.3

For this particular case, I reviewed the literature on the complications of cataract surgery in nanopthalmic eyes and held a detailed discussion of the possible risks of the procedure with the patient and his mother. I emphasized not only the remote risk of infection, but also the real risk of choroidal effusion, choroidal hemorrhage, and malignant glaucoma. Although the patient's eyes were extremely short, their white-to-white diameters and anterior chamber depths indicated fairly normal anterior segments. I felt that the risk of choroidal effusion could be minimized if I used small phaco incisions, kept the eyes pressurized with viscoelastic, and inserted foldable, acrylic, three-piece lenses through a 3.5-mm incision.

The real challenge of this approach was calculating the correct IOL powers. Table 1 summarizes the calculations for this patient using three popular formulas. The numbers refer to the IOL power that each formula suggests for a target correction of -1.00 D for each eye. A study4 by Jack Holladay, MD, of Houston showed that 20% of small eyes also have small anterior segments. His formula requires the white-to-white measurement, as well as the anterior chamber depth, lens thickness, and other parameters, in an attempt to estimate the final position of the IOL in the eye, termed the effective lens position. With these very strong lenses, a 1-mm difference in the effective lens position can result in a 4.00- to 5.00-D error. Table 2 shows the Holladay II calculations for this patient. For the patient's left eye, the predicted postoperative refractive error for two 28.00-D lenses according to each formula was (1) +1.85 D, Hoffer Q; (2) -4.38 D, SRK-T; and (3) +0.10 D, Holladay II.

I performed surgery on the patient in July 1997, first on the left eye and 2 weeks later on his right. There were no complications during the surgery on either eye, and the piggyback lenses were surprisingly easy to place within the capsular bag. Because the 30.00-D lenses were thicker than normal when folded, I had to enlarge the 3.0-mm phaco incision to 3.5 mm. After placing the first lens in the bag, I refilled the anterior chamber with Healon (Pharmacia Corporation, Peapack, NJ) and easily placed the second lens on top of the first. I was quite proud to have been able to place both lenses in the bag.

For the patient's left eye, I had used the Holladay II calculations and chosen two 28.00-D lenses. I had targeted the eye for emmetropia instead of -1.00 to -2.00 D as I usually do in eyes such as his. I had found it hard to believe that his eye required two 28.00-D lenses. Once I realized that the manifest refraction of the patient's left eye was +2 immediately postoperatively, I elected to place two 30.00-D lenses in his right eye. As it turned out, the Hoffer Q formula had most accurately measured this patient's eyes. The Holladay II had underestimated the powers by 1.00 D OD and 2.00 D OS, while the SRK-T had overestimated the final refraction by 8.00 D OD and 4.00 D OS. The SRK-T had predicted that a total power of 50.00 D was required when the correct number was actually 60.00 D.

OUTCOME
The patient was extremely pleased with his UCVA of 20/60 OD and 20/70 OS. His right eye refracted to -0.50 D, the left to +2.00 D, and he had a UCVA of 20/50 OU. The patient chose not to wear glasses because his visual acuity was the best it had ever been.

His results were stable during the first year, but the patient was then lost to follow-up for over 2 years. When I began to read reports of interlenticular opacification,5 I scheduled the patient for an examination. When I saw him in December 2000, he had no complaints about his vision. His UCVA was 20/100 OD and 20/80 OS and could not be improved by refraction.

The slit lamp examination revealed a cloudy posterior capsule in his right eye. The anterior lens had moved anterior to the capsule, although its loops were still in the bag. There was no interlenticular opacification (Figure 1A). The slit lamp examination of his left eye, however, revealed moderate interlenticular opacification and showed that both lenses were located in the bag (Figure 1B). A similar reported case5 described a 55-year-old patient who had two 17.00-D lenses placed in each eye. That individual developed interlenticular opacification in the eye where the anterior capsule completely encompassed the anterior implant. In his other eye, although both lenses were in the bag, the anterior capsule was peripheral to (instead of encompassing) the anterior implant, and interlenticular opacification was not observed.

I contacted Johnny Gayton, MD, of Warner Robins, Florida, to ask what treatment he would recommend for the interlenticular opacification in the left eye. Dr. Gayton had already treated this complication with some success by applying low-energy Nd:YAG spots to the interlenticular space in an attempt to partially liquefy the membrane. I tried this approach on two occasions with only limited success. Using the Nd:YAG laser, I easily opened the posterior capsule of the right eye (Figure 1C). The patient's UCVA improved to 20/60 without further enhancing the refraction. The UCVA of his left eye remained 20/80 and could not be improved. I have not seen the patient since.

DISCUSSION
I consider clear lensectomy in highly hyperopic eyes (as described in this case) to be the refractive surgical procedure of choice, at least until phakic implants become an available alternative. The procedure is normally straightforward, and the risk of a postoperative retinal detachment should be very low. The challenge of the surgery is accurately calculating the IOL power; both the Holladay II and the Hoffer Q formulas seem to be accurate for these short eyes. It is probably best to use a single lens implant whenever possible. If piggyback lenses are required, placing one in the bag and the other in the sulcus should reduce the risk of interlenticular opacification. There are now several reports of this complication in the literature.6-8 Many surgeons believe that interlenticular opacification develops when the capsular epithelial cells are sealed into position by the adherence of the capsule to the anterior lens. When the cells begin to migrate, they seek the plane of least resistance, which is located between the two lens implants. This complication can be very difficult to handle and can require the removal of both IOLs. If piggyback lenses are required for a full correction, or in cases of secondary piggyback lenses, many refractive surgeons deem it best to place the first lens in the bag and the second in the sulcus. I am unaware of any cases of interlenticular opacification in this situation.

I now avoid using piggyback lenses whenever possible. The P359UV lens (Bausch & Lomb Surgical, San Dimas, CA) is available in powers of up to 44.00 D. This one-piece PMMA lens requires a 5.5- to 6.0-mm incision for placement and may be a better option than piggyback lenses for eyes that do not require more than 44.00 D of correction.
James J. Salz, MD, practices at the American Eye Institute in Los Angeles. He does not hold a financial interest in any of the technologies or companies mentioned herein. Dr. Salz may be reached at (323) 653-3800; jjsalzeye@aol.com.
1. Lyle WA, Jin GJ. Clear lens extraction to correct hyperopia. J Cataract Refract Surg. 1997;23:1051-1056.
2. Siganos DS, Pallikaris IG. Clear lensectomy and intraocular lens implantation for hyperopia from +7 to + 14 diopters. J Cataract Refract Surg. 1998;14:105-113.
3. Kolahdouz-Isfahami AH, Rostamian K, Wallace D, Salz JJ. Clear lens extraction with intraocular lens implantation for hyperopia. J Cataract Refract Surg. 1999;15:316-323.
4. Holladay JT, Gills JP, Leidlein J, Cherchio M. Achieving emmetropia in extremely short eyes with two piggyback posterior chamber intraocular lenses. Ophthalmology. 1996;103:1118-1123.
5. Gayton, JL, Apple DJ, Peng Q. Interlenticual opacification: Clinical pathologic correlation over complications of posterior chamber intraocular lenses. J Cataract Refract Surg. 2000;26:330.
6. Werner L, Apple DJ, Pandley SK, et al. Analysis of elements of interlenticular opacification. Am J Ophthalmol. 2002;133:320-326.
7. Spencer TS, Mamalis N, Lane SS. Interlenticular opacification of piggyback acrylic intraocular lenses. J Cataract Refract Surg. 2002;28:1287-1290.
8. Jackson DW, Koch DD. Interlenticular opacification associated with asymmetric haptic fixation of the anterior intraocular lens. Am J Ophthalmol. 2003;135:106-108.
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