Phakic Posterior Chamber Intraocular Lenses for the Correction of High Myopia

Long-term follow-up of first-generation posterior chamber phakic intraocular lens

We present a patient who received a first-generation posterior chamber phakic intraocular lens (PC pIOL) (Fyodorov IOL) to correct myopia 18 years previously. After a long lapse in the follow-up, the patient presented with a reduced endothelial cell count. Although the cataractogenic effect of first-generation PC pIOLs is well known, no sign of cataract was present. The patient was totally satisfied even after 18 years. To our knowledge, this is the first report of a long follow-up of a patient implanted with a first-generation PC pIOL.

Decentration and Cataract Formation 10 Years Following Posterior Chamber Silicone Phakic Intraocular Lens Implantation

PURPOSE

To report a 10-year follow-up for bilateral implantation of a Chiron Adatomed silicone posterior chamber phakic intraocular lens (PIOL).

METHODS

A 32-year-old man presented with bilateral blurred vision and monocular diplopia in the left eye of 2 years' duration.

RESULTS

Slit-lamp microscopy showed bilateral anterior subcapsular cataract and temporal PIOL decentration, and no visible space between the PIOL and crystalline lens in the right eye. After explantation of the posterior chamber PIOL, lens aspiration, and IOL implantation, uncorrected visual acuity improved to 20/15 in the right eye. Scanning electron microscopy examination showed denser deposits on the central portion of the back surface when compared with the edges.

CONCLUSIONS

Long-term follow up of certain designs of posterior chamber PIOLs may reveal late occurrence of complications. Cataract formation may be related to direct contact between the implanted and crystalline lenses.

Phakic Intraocular Lenses

An analytical review of the data available in the field of phakic intraocular lens implantation was conducted. Particular attention was paid to the more critical issues of intraocular lens sizing and safety guidelines. A comprehensive, competitive analysis of different implantation sites, intraocular lens model designs, and safety guidelines has been included. Specialized biometry techniques, such as very high frequency ultrasound and Scheimpflug imaging, have been reviewed, and a critical review of commercial claims regarding intraocular lens technologies has been included. Clinical studies of phakic intraocular lenses demonstrate increasing promise for the correction of refractive errors not amenable to mainstream excimer laser refractive surgery. The main issues currently revolve around adequate lens design (VHF ultrasound study suggests that custom-design and sizing may be the most effective and safest approach for every phakic IOL model), because these devices will be required to remain physiologically inert and anatomically compatible with internal ocular structures and relations for several decades. The possibility of safe removing or exchanging the IOL should remain a feasible option over time. It is of utmost importance that we continue to critically evaluate current encouraging short-term outcomes, which are being extrapolated to the longer term by ongoing high resolution imaging and monitoring of the anatomical and functional relations of implanted phakic IOLs.

Ultrasound biomicroscopy of silicone posterior chamber phakic intraocular lens for myopia

PURPOSE

To study the intraocular position and anatomic relationships of PRL-III (phakic refractive lens) (PRL) posterior chamber phakic intraocular lens (PCP IOL) for high myopia using ultrasound biomicroscopy (UBM).

SETTING

Centro Oftalmológico Real Vision, and Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain.

METHODS

Sixteen phakic myopic eyes that had had PRL implantation were examined by UBM 1 month after surgery. The PRL position, PRL-crystalline lens peripheral distance, and central distance between the corneal endothelium and the PRL were measured.

RESULTS

Both haptics were on the zonule in 6 eyes, in the ciliary sulcus in 5 eyes, and impacted in the ciliary body in 1 eye. In the 4 remaining eyes, the haptics were in mixed positions. The mean PCP IOL crystalline lens peripheral distance in the minor axis was 588.1 microm +/- 232.5 (SD), and the mean PCP IOL-endothelium central distance was 2082.8 +/- 277.6 microm.

CONCLUSIONS

Phakic refractive lens implantation should be done carefully because of the sulcus location of the haptics in many cases. This, with the iris-PRL contact, suggests caution for the long-term outcome.

High-frequency ultrasound biomicroscopy of silicone posterior chamber phakic intraocular lens for hyperopia

PURPOSE

To study the intraocular position and anatomic relationships of the PRL-III phakic refractive lens (PRL), a posterior chamber phakic intraocular lens (PCP IOL), in cases of hyperopia using ultrasound biomicroscopy (UBM).

SETTING

Centro Oftalmológico Real Vision, Madrid, Spain, and Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense, Madrid, Spain.

METHODS

Eleven phakic hyperopic eyes of 6 patients who had PRL implantation were examined by UBM 1 month after surgery. The PRL position, PRL-crystalline lens peripheral distance, and central distance between the corneal endothelium and the PRL were measured.

RESULTS

Eight eyes had both haptics on the zonule, 2 had 1 haptic in the sulcus and 1 on the zonule, and 1 had 1 haptic in the sulcus and the other in the ciliary body. The mean PCP IOL-crystalline lens peripheral distance in the minor axis was 239.7 microm +/- 179.4 (SD) and the mean PCP IOL-endothelium central distance, 2146.98 +/- 219.6 microm. Contact between the PCP IOL and crystalline lens was observed in 1 eye.

CONCLUSIONS

In this study of hyperopic eyes, the PRL was located on the zonule in most cases. However, the location of the haptics in the sulcus and contact between the PCP IOL and the crystalline lens that occurred in some cases suggest further study of possible long-term complications is needed.

Ultrasound biomicroscopy and Scheimpflug photography of angle-supported phakic intraocular lens for high myopia

PURPOSE

To evaluate the equivalence of Scheimpflug photography (SP) and ultrasound biomicroscopy (UBM) in determining corneal epithelium-intraocular lens (IOL) and border IOL-iris distances.

SETTING

Universität Erlangen-Nuremberg, Erlangen, Germany.

METHODS

In 26 eyes of 17 patients who had a NuVita MA20 angle-supported anterior chamber intraocular lens (Chiron-Domilens), SP and UBM were used to evaluate the distance between the endothelium and the anterior IOL face in central and peripheral regions (12 o'clock and 6 o'clock positions) and between the border of the anterior IOL face and the iris. The Wilcoxon test was used for statistical analysis.

RESULTS

The mean central endothelium-anterior IOL face distance was 2.01 mm and 2.00 mm by SP and UBM, respectively. The mean peripheral endothelium-anterior IOL border distance was 1.28 mm and 1.58 mm, respectively, and the mean peripheral anterior IOL face-iris distance, 0.89 mm and 0.75 mm, respectively.

CONCLUSIONS

The difference between the 2 methods in the central endothelium-anterior IOL face distance was not significant (methods were equivalent), but the difference in the peripheral endothelium-anterior IOL face distance was. This may be the result of difficulty in obtaining the exact transition point between the IOL and the haptics by SP examination. The difference between the 2 methods in the IOL border-iris distance was also significant because of the irregularity of the iris surface; therefore, measurements were performed at different sites along this structure. The significant differences in the peripheral endothelium-IOL and IOL border-iris distances indicate that although both methods are useful, they are not equivalent.

Phakic posterior chamber intraocular lens pupillary block

A 49-year-old woman developed bilateral pupillary block after implantation of a phakic posterior chamber intraocular lens despite patent-appearing but nonfunctional peripheral iridotomies. This case serves as a basis to identify clinical signs that distinguish this diagnosis from other causes of elevated intraocular pressure and types of pupillary block.

Gonioscopic changes after implantation of a posterior chamber lens in phakic myopic eyes

PURPOSE

To evaluate the effects of posterior chamber implantation of phakic intraocular lenses on angle structures and the correlation with intraocular pressure (IOP).

SETTING

Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria.

METHODS

A Staar implantable contact lens (ICL) was implanted in 20 white patients (34 eyes) with high myopia. The patients were followed for a mean of 2.3 years (range 0.8 to 6.0 years). Two subgroups were created: One had a follow-up of 2.4 to 6.0 years and the other, 0.8 to 2.3 years. The mean spherical power of the implanted ICL was -16.8 diopters (D) (range -9.0 to -21.0 D). The angle structures were examined by gonioscopy using the Spaeth technique, and optical pachymetry and IOP were measured in dilated and undilated pupils. Trabecular pigmentation was measured semiquantitatively. The ICL models included a few prototypes (6 eyes), the V2 model (10 eyes), the V3 model (6 eyes), and the V4 model (12 eyes).

RESULTS

The anterior chamber angle was between 11 and 20 degrees in 41% of eyes, between 21 and 30 degrees in 21%, larger than 30 degrees in 21%, and 10 degrees or smaller in 17%. An apparent iris root insertion was above Schwalbe's line in 6% of eyes, behind Schwalbe's line in 12%, at the scleral spur in 67%, and in a deep angle recess behind the scleral spur in 15%. The curvature of the iris was regular in 19 eyes and steep in 15 eyes. The mean pigmentation in all 4 quadrants was 1.3. (Grade 1 was defined as trace pigmentation.) The mean pachymetry from the endothelium to the ICL anterior surface was 2.7 mm and from the endothelium to the anterior surface of the crystalline lens, 3.2 mm. The mean IOP was 14.1 mm Hg in undilated pupils and 12.1 mm Hg in dilated pupils. There was no correlation between angle pigmentation and IOP.

CONCLUSION

Trace pigmentation in the trabecular meshwork was common after ICL implantation. However, there was no direct influence on IOP. Long-term follow-up is necessary to evaluate the effect and progress of trabecular pigmentation in eyes with an ICL.

The phakic intraocular lens implant: in-depth focus on posterior chamber phakic IOLs

Phakic Intraocular surgery has come a long way in the past 20 years, especially in the evolution of posterior chamber phakic intraocular lenses (PC PIOLs). Clinical trials worldwide are showing acceptable results concerning efficacy, predictability, stability, and safety. PC PIOLS are proving to be a promising option for patients with high and extreme ametropia who cannot benefit from conventional corneal refractive procedures. This article provides an in-depth examination of PC PIOLs, their origin and evolution, and the results of past and current clinical studies. Reports of historical importance and studies published since the 1990s in peer-reviewed journals, textbooks, and monthly eye magazines, as well as Food and Drug Administration preliminary clinical findings, are reviewed. Anterior chamber phakic intraocular lenses are mentioned briefly.

Posterior chamber silicone intraocular lens for the correction of myopia: an experimental study in rabbits

PURPOSE

To establish whether ocular lesions arise after implantation of posterior chamber silicone intraocular lenses (IOL) for the correction of high myopia.

METHODS

Twenty-three posterior chamber silicone IOL were implanted in 23 eyes of the same number of pigmented rabbits. After different follow-up time (from one week to one year) the eyes were enucleated and processed for histopathological study after determining the protein concentration in the aqueous humor. The IOL were removed for staining and examination, and adhered cells were counted. Ten eyes analogous to those operated upon were used as controls.

RESULTS

Intense inflammation was observed in the early postoperative period in all cases. Protein concentration in the aqueous humor was initially high and decreased over time, though without reaching normal values at one year. Mono- and multinucleated cells were seen adhering to the IOL, though they decreased in number over time and were practically absent after one year. Friction between the posterior surface of the iris and the IOL had no clinical repercussions. The only pigment accumulations were in the iris and in the peritrabecular zone. There were no significant differences in the accumulation of granules in relation to IOL diameter or power. Excluding three cataracts morphologically similar to traumatic cataracts, five lens opacifications were observed: two were anterior subcapsular cataracts, and the other three were only precapsular deposits. The IOL had no synechiae to the ocular tissues.

CONCLUSIONS

Opacification of the lens is the main concern with implanted posterior chamber silicone IOL. Larger series of eyes must be analysed to establish the true incidence and reversibility of these opacities.

High incidence of cataract formation after implantation of a silicone posterior chamber lens in phakic, highly myopic eyes

OBJECTIVE

To assess the effectiveness and safety of implantation of a negative, silicone, posterior chamber intraocular lens (IOL) in the ciliary sulcus of phakic, highly myopic eyes.

DESIGN

Noncomparative consecutive interventional series.

PARTICIPANTS

Eighteen eyes of 10 patients suffering from high-degree myopia (spherical equivalent < -10 diopters) undergoing implantation of a Fyodorov 094M-1 IOL by the same surgeon (P.H.B.) were evaluated.

INTERVENTION

A standard surgical technique was used in all patients under peribulbar anesthesia. The IOL was implanted in the ciliary sulcus immediately in front of the natural lens under protection of a viscoelastic substance (Healon) through a 3.5-mm temporal or nasal clear-corneal tunnel. No sutures were necessary in any case. A peripheral iridectomy was performed intraoperatively in 14 eyes, whereas 4 additional eyes received a yttrium-aluminum-garnet peripheral iridectomy after surgery. At the end of surgery, gentamicin and dexamethasone were given both topically and subconjunctivally.

MAIN OUTCOME MEASURES

Visual acuity and refraction were measured before surgery, as well as 1 day, 3 months, 6 months, and 2 years after surgery. Postoperative complications were recorded.

RESULTS

Best-corrected visual acuity remained unchanged (1 eye) or improved (6 eyes by 1, 5 eyes by 2, and 2 eyes by 3 Snellen lines, respectively) in 14 of 17 eyes, whereas 3 eyes experienced a decrease in best-corrected visual acuity by 1 Snellen line. Postoperative refraction approached the desired slight undercorrection at all times of examination. Cataract formation of the anterior subcapsular (8 eyes) or nuclear (only 1 eye) type was observed in overall 9 (52.9%) of 17 eyes. When considering only the patients with a follow-up of 2 years, the incidence of cataract formation was 81.9% (9 of 11 eyes).

CONCLUSIONS

The high incidence of cataract formation should discourage the implantation of the type of IOL used in this study in phakic eyes to correct high-degree myopia.

Pathological examination of an explanted phakic posterior chamber intraocular lens

PURPOSE

To report the clinicopathological correlation of an explanted phakic posterior chamber intraocular lens (PPC IOL) and to study the conformation of this lens implanted into human eyes obtained postmortem.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Three silicone PPC IOLs were explanted. One lens, explanted from a 38-year-old woman with complicated cataract, was submitted for pathological analysis. In addition to gross and scanning electron microscopy (SEM), the lens was studied after experimental implantation in human eyes obtained postmortem using frontal, posterior, and side-view techniques.

RESULTS

Although gross and SEM showed that the IOL was well polished, examination of the lens in human cadaver eyes showed it was oversized and poorly fixated. It was relatively bulky in its anterior-posterior dimension and revealed evidence of significant contact with the iris and crystalline lens.

CONCLUSIONS

This study illustrates many pitfalls to be avoided in the design of a plate PPC IOL. The lens in this report was too large, and instead of ciliary sulcus fixation, it showed poor fixation through the zonules onto the posterior face of the pars plicata. Present and future PPC IOLs should be submitted for similar preclinical studies to clarify the type and site of fixation.

Very high frequency ultrasound analysis of a new phakic posterior chamber intraocular lens in situ

PURPOSE

To use very high frequency ultrasound scanning for in situ analysis of a new phakic posterior chamber intraocular lens (No-Touch; International Visions Inc, Cincinnati, Ohio).

METHODS

In this pilot study, very high frequency ultrasound (50 MHz) wide-angle (15 mm) full anterior segment scans were obtained in two patients who had undergone phakic posterior chamber intraocular lens implantation into legally blind eyes with normal anterior segment anatomy.

RESULTS

Very high frequency ultrasound B-scan images delineated the phakic posterior chamber intraocular lens within the posterior chamber. The relations to the sulci were clearly imaged. Anatomic relations of the phakic posterior chamber intraocular lens optic and haptics were visualized in both static (light/dark) and kinetic (distance/accommodative) states.

CONCLUSION

Very high frequency ultrasound wide-angle scanning provides a unique tool to noninvasively evaluate the eye preoperatively and the static and kinetic relations of this new refractive device within the posterior chamber.

Bilateral Cataract after Phakic Posterior Chamber Top Hat-style Silicone Intraocular Lens

BACKGROUND

New strategies have been developed for surgical treatment of high myopia. Recently, implantation of minus power posterior chamber intraocular lenses (IOL) into phakic eyes has been introduced.

METHODS

We report a 37 year-old female patient who developed bilateral anterior subcapsular cataract 7 years after minus-power, top hat-style silicone posterior chamber IOL implantation in Russia. The corrected visual acuity was right eye 20/200 and left eye 20/63. Because of the high myopia and the posterior chamber IOL in her phakic eyes, biometry for IOL calculation gave contradictory results. Both posterior chamber IOLs were found to be adherent to the crystalline lenses. After posterior chamber IOL explantation and phacoemulsification, intraoperative retinoscopy was performed. With this aphakic refraction, the IOL power was calculated and implanted. The explanted posterior chamber IOLs were examined by scanning electron microscopy.

RESULTS

After bilateral operation the corrected visual acuity increased to right eye 20/32 and left eye 20/40, respectively. On scanning electron microscopy, a membranous structure of unknown origin was noted on the entire surface of the explanted posterior chamber IOLS.

CONCLUSION

There is a potential risk of cataract formation after implantation of this top hat-style silicone posterior chamber IOL. If cataract extraction in this specific situation is needed, a different approach for calculating the aphakic IOL power is necessary, such as intraoperative retinoscopy.