CASE REPORT

Correction of accommodative esotropia using hyperopic implantable collamer lenses

Gonzalez-Lubcke, Eduardo MD; Navas, Alejandro MD, MSc, PhD; Graue-Hernandez, Enrique O. MD, MSc; Ramirez-Miranda, Arturo MD, MSc; Gomez-Bastar, Arturo MD

Author Information
JCRS Online Case Reports 10(3):p e00082, July 2022. | DOI: 10.1097/j.jcro.0000000000000082
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Abstract

Accommodative esotropia is a form of strabismus characterized by convergent misalignment of the visual axes, typically associated with hyperopia and driven by accommodation. Treatment requires round-the-clock wear of the full hyperopic refractive error, as determined by cycloplegic refraction. Hyperopic correction is the most reliable method for achieving othotropia and maintaining binocular vision.1

Refractive surgery has become a common alternative to spectacles for the correction of refractive errors in adults with strabismus.2 However, corneal refractive procedures in hyperopia greater than 4.00 diopters (D) represent a challenge because of their unpredictability and high regression rates. Loss of greater than 2 lines of corrected distance visual acuity (CDVA) is significantly more frequent in corrections greater than +6.00 D.3 Phakic intraocular lenses (pIOLs) offer advantages such as reversibility, precision, a wide range of correction, stability, and preservation of accommodation.4

The Visian implantable collamer lens (ICL) (STAAR Surgical Co.) is a posterior chamber pIOL (PC pIOL) made from collamer, a biocompatible hydrophilic copolymer and hydroxyethyl methacrylate with an ultraviolet light–filtering chromophore. This ICL is reported to be effective in the correction of moderate to high myopia and moderate to high hyperopia.5,6

To the author's knowledge, limited reports are available in the literature regarding the management of accommodative esotropia with a PC pIOL implantation. The following case describes the successful management of accommodative esotropia using a hyperopic ICL.

Patient Consent Statement

The patient provided written informed consent for publication in a journal article.

CASE REPORT

A 21-year-old man with fully accommodative esotropia was bothered by the use of spectacles and uncompliant to contact lenses because of poor tolerability. Unchanged ocular alignment along with a stable manifest and cycloplegic refraction was confirmed 2 years prior to the procedure. Informed consent was obtained, and a toric hyperopic ICL implantation was performed on both eyes.

Preoperative and postoperative evaluation included uncorrected distance visual acuity (UDVA), CDVA, manifest and cycloplegic refractions, estimated 30 minutes after instillation of cyclopentolate 1%, slitlamp biomicroscopy, gonioscopy, applanation tonometry, and fundus examination, topographic and tomographic findings, and a full strabologic evaluation. The angle of deviation was measured in prism diopters (PD) using an alternate prism cover test at 6 m for distance and 33 cm for near.

The manifest refraction was +7.00 −1.75 × 180, with a UDVA of 20/60 and CDVA of 20/30 in the right eye. In the left eye, the manifest refraction was +7.00 −2.00 × 180, with a UDVA of 20/60 and CDVA of 20/20. The cycloplegic refraction was +7.50 −2.00 × 180 in both eyes, with a CDVA of 20/30 in the right eye and 20/20 in the left eye. On his strabologic examination, without wearing his full cycloplegic refraction, he presented with a 30 PD esotropia for both distance and near, which improved to 5 PD esotropia in both distances with full cycloplegic correction. Ductions and versions were full. Slitlamp examination, pupillary reflex, intraocular pressure, and dilated fundus examination findings were normal.

Scheimpflug corneal tomography (Pentacam, Oculus Surgical, Inc.) showed pachymetry at the thinnest point of 563 μm and 562 μm, anterior chamber depth of 3.26 mm and 3.41 mm, and mean keratometry of 41.5 D and 41.6 D in the right and left eyes, respectively. Corneal topography (Orbscan II, Bausch & Lomb, Inc.) revealed white-to-white measurements of 12.0 mm in both eyes and anterior chamber depth of 3.49 in the right eye and 3.56 mm in the left eye. The endothelial cell count was 2907 μm3 in the right eye and 2903 μm3 in the left eye measured at the center of the cornea with a noncontact specular microscope (Nidek CEM-530, Nidek Co., Ltd.).

ICL power was calculated using the software provided by the manufacturer (https://evo-ocos.staarag.ch). Emmetropia was selected as the target refraction. The power and length of the implanted ICLs were determined based on cycloplegic refraction, keratometries, corneal thickness, anterior chamber depth, and horizontal white-to-white distance. A Visian toric ICL for hyperopia and astigmatism (VTICH) 12.6 mm, power +7.50/+2.5/087 for the right eye, and a VTICH 12.6 mm, power +7.50/+2.5/085 for the left eye, were implanted.

In brief, the procedure was performed under topical anesthesia using tetracaine eyedrops 0.5%, supplemented with intravenous sedation. Pupil was dilated 30 minutes preoperatively with tropicamide–phenylephrine drops. The ICL was implanted through a 3 mm clear corneal incision in the horizontal temporal meridian using an injector cartridge supplied by the manufacturer. The ICL was carefully placed in the sulcus and positioned with the axis properly aligned. Two peripheral iridectomies were performed at the 11 and 1 o'clock positions. The procedures were performed 1 week apart between both eyes.

The procedure was completed successfully without any surgical complications. Twelve months postoperatively, UDVA was 20/30 in the right eye and 20/25 in the left eye; the manifest refraction became +0.75 −0.75 × 180 in the right eye, with a CDVA of 20/25, and +0.25 −0.50 × 180 in the left eye, with a CDVA of 20/20. An examination revealed a stable esotropia of 5 PD at both distance and near. Ductions and versions remained full (Figure 1). No complications such as intraocular pressure elevation or cataracts occurred during the follow-up (Figure 2). Scheimpflug images using Pentacam showed ICL well positioned in sulcus with a 690 μm vault in the right eye and 610 μm vault in the left eye. The endothelial cell count was 2787 μm3 in the right eye and 2702 μm3 in the left eye.

F1
Figure 1.:
Postoperative photographs demonstrating esotropia of 5 prism diopters with complete ductions and versions without spectacles after ICL implantation.
F2
Figure 2.:
Slitlamp photograph of the right eye (A, B) and left eye (C, D) showing the 2 peripheral iridectomies at the 11 and 1 o'clock positions and the phakic intraocular lenses adequate located.

DISCUSSION

Corneal refractive surgery has been successfully used to treat accommodative esotropia. Sabetti et al. obtained good results in the reduction of the angle of deviation in patients with fully and partially accommodative esotropia using photorefractive keratectomy or laser-assisted in situ keratomileusis.7 Similarly, Hoyos et al. reported that all patients treated with laser-assisted in situ keratomileusis achieved ortophoria or a microtropia without optical correction postoperatively.8

Although the literature supports the use of corneal refractive surgery in the treatment of fully accommodative esotropia, there is a potential risk for complications associated with high hyperopia correction, such as corneal scarring, higher regression rates, less predictable refractive outcomes, and induction of higher-order aberrations.9,10

Phakic intraocular lenses offer some advantages over keratorefractive surgeries, including the possibility of treating a wider range of refractive errors, better predictability of visual outcomes in high ametropia, faster visual rehabilitation, more stable results, fewer incidences of dry eye, and better visual quality. In addition to preserving corneal anatomy, pIOL implantation is potentially reversible and accommodation is preserved.11,12

Galin et al. reported control of esotropia and some improvement in fusional ability in a patient with hyperopia and accommodative esotropia treated with bilaterally angle-supported refractive implants.13 Based on the location where the pIOLs are implanted, the endothelial cell loss could be greater with anterior chamber pIOL compared with that with PC pIOL, and among anterior chamber pIOLs, angle-supported pIOLs have a greater endothelial cell loss than the iris-fixated IOLs.14

Limited reports are available in the literature regarding the implant of posterior chamber pIOL in patients with accommodative esotropia. To the author's knowledge, there is only 1 case series report of 3 patients. In this publication, Shi and colleagues reported that the use of ICL implantation to treat accommodative esotropia in adults was effective and safe. Preoperatively, the mean esotropia at near was 25 PD (range: 20 to 30 PD). Postoperatively, all patients achieved ortophoria or microesophoria. Postoperative uncorrected distance visual acuity significantly increased at distance and near. One patient complained of glare when driving at night, but this phenomenon gradually disappeared after 3 months. No other complications were described.15

In this report, the uncorrected visual acuity improved significantly, and even the right eye gained 1 line of CDVA. The spherical equivalent was +0.38 D for the right eye and 0.00 D for the left eye. The patient achieved preoperative microtropia without the need for spectacles. No intraoperative or postoperative complications were observed.

As with any intraocular surgery, complications can occur. However, evidence indicates that ICL implantation is a safe, effective, predictable, and stable method for the correction of moderate and high hyperopia, provided that the following criteria are fulfilled: age older than 21 years, stability of refraction, clear crystalline lens, and anterior chamber depth above 3.00 mm.11,12

The expected result in ocular alignment will be the one observed with the full cycloplegic correction when using spectacles or contact lenses, and a residual hyperopia will dictate the amount of esotropia driven by accommodation. In this sense, the ocular alignment should remain as stable as if the hyperopia was corrected by any other means. The power calculation of the ICLs in cases of fully accommodative esotropia should be made based on the cycloplegic refraction.

The new ICL models for myopic correction are designed with a 360 μm central port that allows sufficient aqueous flow to maintain the normal physiology of the anterior segment of the eye. This central port eliminates the need for iridotomy/iridectomy. However, ICLs for hyperopic correction do not feature a central port, and therefore, the creation of iridectomy is required to prevent pupillary block. Hyperopic eyes are at a greater risk for developing intraocular pressure alterations compared with myopic eyes. Consequently, only eyes with anterior chamber depths of 3.0 mm or greater should be treated with a pIOL implantation.

In conclusion, our case report suggests that hyperopic ICL may be a safe and effective option for the surgical treatment of accommodative esotropia in adults who are not candidates for corneal-based surgery. A further study of large series should be performed to assess the long-term stability of this procedure in adults and younger patients.

WHAT WAS KNOWN

  • Refractive surgery has been successfully used to treat accommodative esotropia. Nevertheless, corneal refractive procedures in hyperopia greater than 6.00 D represent a challenge because of their unpredictability and high regression rates.
  • The use of pIOLs to treat accommodative esotropia has been tried with success. However, limited reports are available in the literature.

WHAT THIS PAPER ADDS

  • Toric hyperopic ICL may be a safe, effective, and reversible option for the surgical treatment of accommodative esotropia and high hyperopia with anterior chamber depth of 3.0 mm or greater.

Acknowledgments

The authors thank Santiago Ruano-Valenzuela, MD, MSc, for his assistance in the strabological examination.

REFERENCES

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Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of ASCRS and ESCRS
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