Effect of accommodation and pupil size on the movement of a posterior chamber lens in the phakic eye

[Ultrasound biomicroscopy of posterior chamber phakic intraocular lenses: a comparative study between ICL and PRL models]

PURPOSE

To evaluate the anatomic relationships of the implantable contact lens (ICL) and the phakic refractive lens (PRL) posterior chamber phakic intraocular lenses (PCP IOL) using ultrasound biomicroscopy (UBM).

MATERIAL AND METHODS

Seventeen phakic myopic eyes corrected with ICL, and 14 phakic myopic eyes that had had PRL implantation, were examined retrospectively using UBM. The main parameters measured and compared were anterior chamber depth, central and peripheral distance between PCP IOL and the crystalline lens, and exact lens haptic position.

RESULTS

The mean distance between the PCP IOL and the central endothelium was 2398+/-203 microm and 2640+/-230 microm in the ICL and PRL groups, respectively. The central vault between the implant and the crystalline lens was greater in eyes with ICL (ICL, 402+/-194 microm; PRL, 256+/-187 microm, p<0.05). However, the incidence of lens contact on the peripheral level was higher in the ICL group (41%) than in the PRL group (29%), and the difference between the two implants in the peripheral crystalline lens-PCP IOL distance was significant (p<0.05). Both IOL haptics appeared to be correctly positioned in the sulcus in 13 (76%) eyes of the ICL group, and on the zonule in eight eyes (57%) of the PRL group.

CONCLUSIONS

PCP IOL implantation is a safe procedure for the correction of high myopia with regard to refractive results. UBM provides a unique tool to noninvasively evaluate the relations of these implants within the posterior chamber, and helps to analyze the mechanisms of crystalline lens and iris complications.

Cataractous Changes due to Posterior Chamber Flattening with a Posterior Chamber Phakic Intraocular Lens Secondary to the Administration of Pilocarpine

OBJECTIVE

To present the first reported case of cataract formation as a consequence of instillation of pilocarpine in an eye with a posterior chamber phakic intraocular lens (IOL).

DESIGN

Interventional case report.

INTERVENTION

A 46-year-old man received a hyperopic implantable collamer lens (ICL) bilaterally.

MAIN OUTCOME MEASURES

Determination of best-corrected visual acuity (BCVA); contrast sensitivity testing with and without glare; and intraocular pressure (IOP), specular endothelial cell, and slit-lamp examinations were performed serially. In addition, the distance between the ICL and crystalline lens was measured with optical coherence tomography.

RESULTS

Both eyes underwent uneventful ICL implantation for the correction of a manifest spherical equivalent of +7 diopters (D) in the right eye and +7.1 D in the left eye. The left eye was followed for 2 years without developing complications. The right eye, however, showed on the first postoperative day a fleckenlike opacification on the anterior pole of the crystalline lens after instillation on the operative day of 2% pilocarpine in an attempt to accelerate recovery from unwanted pupil dilation causing patient complaints of glare disability after surgery. Optical coherence tomography demonstrated complete contact of the ICL with the natural lens 24 hours postoperatively. Serial IOP measurements were always within the normal limits. The instillation of 1% cyclopentolate resulted in an increase in the ICL vault that measured 132 mum 24 hours later. Three days after the completion of a 3-day course of topical 1% cyclopentolate, the opacification was less dense and demarcated, and a 124-mum vault was measured. Three months postoperatively, the cataract was associated with a 3-line loss of BCVA and considerable degradation of the contrast sensitivity, especially at higher spatial frequencies and with a glare source, and corneal endothelial cell changes were within normal limits. One year after ICL implantation, the right eye had to undergo phacoemulsification and IOL implantation, which were uneventful.

CONCLUSIONS

Posterior chamber flattening with resulting crystalline lens opacification can occur immediately after the instillation of pilocarpine in an eye with a hyperopic ICL. Therefore, caution should be taken with the administration of cholinergic agonists such as pilocarpine in patients with phakic IOLs, at least if they are hyperopic ICLs.

Surgical Correction of Hyperopia

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.

Age-related behavior of posterior chamber lenses in myopic phakic eyes during accommodation measured by anterior segment partial coherence interferometry

PURPOSE

To evaluate age-related position shifts of the crystalline lens and the implantable contact lens (ICL, Staar Surgical) by a new, commercially available, anterior segment partial coherence interferometer, the ACMaster (Carl Zeiss Meditec), during accommodation in myopic eyes.

SETTING

ALZ Augenklinik, Munich, Germany.

METHODS

Fifty-three eyes of 29 consecutive patients were measured after myopic ICL implantation before and during subjective accommodation to a stimulus of 3 diopters (D) by anterior segment partial coherence interferometry (PCI). Nine eyes were also measured with a 5.00 diopters (D) stimulus; 14 eyes were measured repeatedly at different visits. The mean patient age was 33 years +/- 9 (SD) (range 21 to 59 years). The preoperative mean sphere was -7.6 +/- 1.9 D (range -5.0 to -11.5 D) and the cylinder, -1.4 +/- 1.1 D (range 0 to -4.25 D).

RESULTS

Older patients had a tendency toward smaller vaults on desaccommodation between the ICL and the crystalline lens compared to younger individuals. In younger patients, there was a decrease of the vault on accommodation, whereas it increased in older persons (P = .005). During accommodation, the more the anterior lens surface shifted forward, the more the ICL bulged (P = .005). The change in vaulting was significantly larger at 5.00 D than at 3.00 D accommodation stimulus (P = .012).

CONCLUSIONS

The behavior of ICLs in relation to the crystalline lens during accommodation varied with age and could be shown by PCI. The position shift of the ICL depended on the initial vault at desaccommodation and the ability of the anterior lens surface to bulge forward. Even though the crystalline lens stiffened, and therefore accommodation deteriorated with age, there was still a movement of the ICL, pointing to the role of the ciliary muscle movement in accommodation.

Phakic intraocular lenses

PURPOSE OF REVIEW

Laser in-situ keratomileusis has been tremendously successful in treating patients with mild and moderate ametropias. For patients with high degrees of refractive error, however, phakic intraocular lenses provide superior quality of vision without the risk of corneal ectasia. Early international results, as well as United States Food and Drug Administration clinical trials, have demonstrated the early safety and efficacy of phakic intraocular lenses. Nevertheless, long-term corneal endothelium cell density and crystalline lens clarity remain a concern.

RECENT FINDINGS

Several new studies demonstrate the superior visual outcomes of phakic intraocular lenses over laser in-situ keratomileusis in patients with moderate and high myopia, particularly in the areas of visual quality and contrast sensitivity. New anterior segment imaging and measurement technologies have provided valuable information about in-vivo structure and function, with and without phakic lens implants. More is being learned about long-term endothelial cell stability and cataract formation, particularly in relation to implant positioning. New applications of phakic intraocular lenses in presbyopia and in other conditions are being explored.

SUMMARY

Once plagued by complications and marginal outcomes, improved designs of phakic intraocular lenses are providing increasing safety and efficacy for the correction of severe ametropias. Long-term concerns with endothelial cell loss remain, but recent data suggest stabilization with time. Proper sizing and positioning are important and increasingly achievable with new imaging modalities. With continued research and experience, phakic intraocular lenses are becoming an invaluable addition to the mainstream refractive surgery armamentarium.

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.

Clinical outcomes of phakic refractive lens in myopic and hyperopic eyes: 1-year results

PURPOSE

To confirm the safety, efficacy, and predictability of the surgical correction of myopia and hyperopia with the phakic refractive lens (PRL) (Medennium Inc.).

SETTING

St. Eriks Eye Hospital, Stockholm, Sweden.

METHODS

This was a prospective clinical study of 20 eyes, 14 myopic and 6 hyperopic, that had PRL implantation at St. Eriks Eye Hospital from April to November 2002. Examinations were performed preoperatively and 1 day, 1 week, 3 months, and 1 year postoperatively. Follow-up included evaluation of the PRL rotation with retroillumination photography, evaluation of the distance between the PRL and the crystalline lens with Scheimpflug image, laser flare, endothelial cell count, uncorrected (UCVA) and best corrected (BCVA) visual acuity, residual refractive error, refractive stability, intraocular pressure, and induced cataract.

RESULTS

Postoperatively, 11 eyes (55%) gained 1 or more lines, 5 eyes (25%) had no change, and 4 eyes (20%) lost 1 line of BCVA. No eye lost 2 or more lines. Mean UCVA was 0.87+/- 0.29 postoperatively. Laser flare values were highest 1 day after operation with normalization at 3 months and without changes at 1 year (P<.05). A rotation of 10 degrees or more was found in 15 eyes (75%) during the first year. The distance between the PRL and crystalline lens was considerably less at 1 year than at baseline (P<.05). There was no statistically significant endothelial cell loss induced by the PRL (P<.05). No induced cataract, glaucoma, or inflammation was observed. In 1 hyperopic eye, horizontal iris transillumination defects were noticed at 1 year.

CONCLUSION

Safety and efficacy indexes were high at 1-year follow-up. The PRL rotated slightly in the posterior chamber. The distance between the PRL and the crystalline lens was considerably less at 1 year than at baseline.