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Keywords:

  • astigmatism;
  • cataract surgery;
  • keratoconus;
  • myopia;
  • piggyback intraocular lenses

Abstract

  1. Top of page
  2. Abstract
  3. Case Report
  4. Discussion
  5. References

The majority of those with keratoconus can maximise visual acuity with spectacle or contact lens correction as they age; however, as subjects enter their sixties, cataracts may supervene and contact lens tolerance diminishes with consequent reduction in visual acuity. Following cataract extraction, the complex refractive error associated with keratoconus may not be readily corrected by an intraocular lens alone. This report highlights the planned implantation of a primary posterior chamber toric intraocular lens with a secondary piggyback, sulcus-based, intraocular lens in advanced but stable keratoconus with extreme myopic astigmatism and cataract.

Piggyback or supplementary secondary intraocular lenses (IOLs) were first described approximately two decades ago to provide sufficient dioptric power in eyes that were highly ametropic and not fully corrected by the range of powers available for single IOLs following cataract surgery.[1] Piggyback, secondary IOLs may also be used to improve the spherical equivalent in patients with undesirable ‘refractive surprises’ following cataract extraction and IOL implantation.

Traditionally, in planned primary piggyback procedures, both IOLs were implanted in the posterior capsular bag at the time of cataract surgery; however, occasionally this caused the development of inter-lenticular opacification (ILO) with Elschnig pearls in the peripheral interface. This phenomenon is difficult to treat with yttrium aluminium garnet (YAG) laser and might subsequently require the explantation of the IOLs.[2, 3] Methods to improve the technique have gradually evolved and current practice typically involves implantation of the primary lens in the capsular bag while the piggyback lens is placed outside the capsule in the ciliary sulcus.

This brief report demonstrates the utility of combining a primary posterior chamber IOL and a secondary sulcus-based IOL in the correction of extreme myopic astigmatism in advanced but stable keratoconus associated with cataract and contact lens intolerance.

Case Report

  1. Top of page
  2. Abstract
  3. Case Report
  4. Discussion
  5. References

A 65-year-old woman with a history of advanced but stable keratoconus in the right eye (best ever visual acuity with rigid contact lens of 6/9) presented with gradual onset ‘blurring’ of vision and increasing intolerance to rigid contact lens wear. She had undergone left penetrating keratoplasty six years earlier and left phacoemulsification with a toric IOL two years earlier.

Unaided vision was 6/120 right eye and 6/18 left eye (6/9 with spectacle correction). Visual acuity corrected to 6/12 right with a rigid gas-permeable contact lens and auto-refraction confirmed extremely high myopia and astigmatism of -20.00 D/-5.00 D × 30. In contrast, the left eye, after corneal transplantation but prior to cataract surgery with a toric IOL, had a spectacle refraction of -8.00 D/-3.50 D × 80 providing 6/12 visual acuity. This ametropia was significantly less than the right eye and therefore was adequately corrected with a single toric IOL. Slitlamp biomicroscopy revealed a clear right cornea with no scarring and nuclear cataract.

Corneal topography confirmed advanced keratoconus in the right eye with ‘simulated keratometry’ readings of 59.00 D × 127° and 52.57 D × 37° (OPD-Scan, Nidek Co Ltd, Gamagori, Japan) (Figure 1) and an axial length of 27.25 mm (IOL Master, Carl Zeiss Meditec, Oberkochen, Germany). The thinnest part of the cornea of the right eye was 418 μm using the Orbscan II corneal tomography system (Bausch & Lomb, Rochester, NY, USA). Although maximum keratometric values were reasonably similar for the OPD-Scan (59.00 D × 127°) and IOL master (59.84 D × 122°), because of the five degree difference in axes a compromise axis of 125° was chosen for the toric IOL and the magnitude of corneal astigmatism was based upon the OPD-scan.

figure

Figure 1. Corneal topography highlighting severe keratoconus in the right eye with simulated keratometric (Sim K) readings of 59.00 D × 127° and 52.57 D × 37° (OPD-Scan, Nidek Co Ltd, Gamagori, Japan)

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In view of decreased vision, increasing contact lens intolerance and the combination of high spherical and cylindrical error, cataract extraction with a piggyback combination of IOLs was considered to be the best option to give maximum visual acuity in the right eye.

Following biometry and informed written consent, phacoemulsification was performed through a superior scleral section, with insertion of a maximum myopic power (-10.0 D) posterior chamber toric intraocular lens of -10.00/+9.00 D (T-flex model 623T, Rayner, East Sussex, UK) and a supplementary ‘piggyback’ sulcus IOL (-4.00 D) to provide the additional myopic correction required (Sulcoflex model 653L, Rayner) (Figure 2).

figure

Figure 2. From left to right: diagram of the anterior view of a Sulcoflex intraocular lens (IOL) and a toric IOL and a side profile of the relative positions of the toric and Sulcoflex IOLs, highlighting the unique design of the Sulcoflex with large optic diameter and posterior haptic angulation

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Ten weeks post-operatively the spectacle visual acuity was 6/9 in the right eye and the IOL toric axis was aligned at 125° as intended. Despite a degree of irregular corneal astigmatism, the manifest residual refraction was +1.25/-2.00 × 155 (spherical equivalent +0.25 D) compared to a pre-operative estimated spherical equivalent of -22.50 D with 6.50 D of corneal astigmatism. On slitlamp biomicroscopy, the pupil was round and both the primary and secondary IOLs were well-centred and in good relative position, giving an unusual total of four linear light reflexes produced by the light incident on the anterior and posterior surfaces of both IOLs (Figure 3). The media were clear and examination of the fundus demonstrated healthy optic disc and macula.

figure

Figure 3. A well-positioned, stable intraocular lens (IOL) pair, with keratoconic slit beam and clear light reflexes from the four IOL surfaces: (1) the concave posterior surface; (2) the convex anterior surface of the posterior chamber IOL; (3) the concave posterior surface; and (4) the convex anterior surface of the supplementary sulcus-based IOL

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Discussion

  1. Top of page
  2. Abstract
  3. Case Report
  4. Discussion
  5. References

Pseudophakic and phakic toric IOLs have previously been described as an effective treatment option in patients with stable keratoconus.[4, 5] In a retrospective study of 19 cases of ‘in the bag’ toric IOL implantation in patients with stable keratoconus, Ramirez-Miranda and colleagues[6] reported a mean reduction in astigmatism of 69 per cent; however, the IOL model used in that study could only correct a maximum of 4.11 D of astigmatism at the corneal plane and nine of the patients exhibited corneal astigmatism of greater magnitude.[6] The recent introduction of higher cylindrical power IOLs is likely to improve outcomes in terms of lower residual refractive astigmatism. In the current case the limited range of myopic astigmatic IOLs meant that toric IOL implantation alone would not fully correct the patient's refractive error and due to the inherent corneal thinning of keratoconus, a combined laser in situ keratomileusis (LASIK) or surface-based photorefractive procedure was not an option.

Early piggyback IOLs were designed to be placed in the capsular bag; however, this technique brought on complications such as inter-lenticular opacification.[7] Subsequently these secondary IOLs were placed in the ciliary sulcus, resulting in a decrease in the incidence of inter-lenticular opacification due to the presence of an inter-lenticular space.[8, 9] The relatively anterior placement of these lenses (which were originally designed for capsular implantation) and the resulting intermittent contact between the IOL and iris led to reports of an increased incidence of intermittent uveitis-glaucoma-hyphaema (UGH) syndrome, pigment dispersion and/or iris transillumination.[10, 11]

Sulcoflex is the first IOL designed specifically to be implanted in a pseudophakic ciliary sulcus. The implantation of a single intraocular lens is suboptimal for higher refractive corrections as high dioptric-powered IOLs have steep radii that cause a decrease in the modulation transfer function. This subsequently produces a distorted image with poor resolution.[12, 13] In such cases, the Sulcoflex is particularly useful, as it decreases the spherical aberration by breaking down the overall power over two, rather than a single IOL, thus producing an improved axial image quality.

Theoretically, the unique design of large optic diameter and rounded haptics with posterior angulation and rounded optic edge minimises or prevents iris-associated risks identified with earlier ‘piggyback’ lenses;[9] however, this IOL is still relatively new to the market and factors such as the stability of the IOL position (tilt, decentration or anterior-posterior migration) and other associated complications remain to be fully determined.

Clinically, the post-operative appearance (Figure 3) demonstrated a well-positioned, stable IOL pair and the well-defined convex/concave light reflexes from the four IOL surfaces. The presence of a gap between the rear surface of the iris and the IOL should minimise the risk of iris pigment shedding and the gap between the IOL surfaces should decrease the likelihood of inter-lenticular opacification development.

This report demonstrates the value of implanting a secondary sulcus-fixated IOL in achieving optimised refractive outcomes in patients with cataract and extreme refractive errors such as may be encountered in advanced stable keratoconus. Nonetheless, in stable keratoconus, cataract or clear lens extraction with insertion of a toric IOL should typically be reserved for subjects with orthogonal astigmatism and minimal irregular astigmatism on corneal topography. Indeed, the potential for good unaided or spectacle-corrected visual acuity after surgery is essential, as hard contact lens wear in an eye with a toric IOL will make the astigmatic correction in the IOL manifest and thus require a toric correction on the front of the contact lens in order to compensate.

References

  1. Top of page
  2. Abstract
  3. Case Report
  4. Discussion
  5. References
  • 1
    Gayton JL, Sanders VN. Implanting two posterior chamber intraocular lenses in a case of microphthalmos. J Cataract Refract Surg 1993; 19: 776777.
  • 2
    Eleftheriadis H, Marcantonio J, Duncan G, Liu C. Inter-lenticular opacification in piggyback AcrySof intraocular lenses: explantation technique and laboratory investigations. Br J Ophthalmol 2001; 85: 830836.
  • 3
    Gayton JL, Apple DJ, Peng Q, Visessook N, Sanders V, Werner L, Pandey SK et al. Interlenticular opacification: clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses. J Cataract Refract Surg 2000; 26: 330336.
  • 4
    Jaimes M, Xacur-Garcia F, Alvarez-Melloni D, Graue-Hernandez EO, Ramirez-Luquin T, Navas A. Refractive lens exchange with toric intraocular lenses in keratoconus. J Refract Surg 2011; 27: 658664.
  • 5
    Visser N, Gast ST, Bauer NJ, Nuijts RM. Cataract surgery with toric intraocular lens implantation in keratoconus: a case report. Cornea 2011; 30: 720723.
  • 6
    Ramirez-Miranda A, Jaimes M, Graue-Hernandez EO, Ramirez-Luquin T, Navas A. Toric intraocular lens in keratoconus. Cornea 2012; 31: 335336.
  • 7
    Werner L, Apple DJ, Pandey SK, Solomon KD, Snyder ME, Brint SF, Gayton JL et al. Analysis of elements of interlenticular opacification. Am J Ophthalmol 2002; 133: 320326.
  • 8
    Werner L, Shugar JK, Apple DJ, Pandey SK, Escobar-Gomez M, Visessook N, Evans BB. Opacification of piggyback IOLs associated with an amorphous material attached to interlenticular surfaces. J Cataract Refract Surg 2000; 26: 16121619.
  • 9
    Kahraman G, Amon M. New supplementary intraocular lens for refractive enhancement in pseudophakic patients. J Cataract Refract Surg 2010; 36: 10901094.
  • 10
    Apple DJ, Reidy JJ, Googe JM, Mamalis N, Novak LC, Loftfield K, Olson RJ. A comparison of ciliary sulcus and capsular bag fixation of posterior chamber intraocular lenses. J Am Intraocul Implant Soc 1985; 11: 4463.
  • 11
    Mastropasqua L, Lobefalo L, Gallenga PE. Iris chafing in pseudophakia. Doc Ophthalmol 1994; 87: 139144.
  • 12
    Holladay JR, Gills JP, Leidlein JL, Cherchio M: Achieving emmetropia in extremely short eyes with two piggyback posterior chamber intraocular lenses. Ophthalmology 1996; 103: 11181123.
  • 13
    Hull CC, Liu CS, Sciscio A: Image quality in polypseudophakia for extremely short eyes. Br J Ophthalmol 1999; 83: 656663.