Considerations when implanting mIOLs in amblyopia with strabismus patients

March 26, 2018

Multifocal IOLs (mIOLs) can provide excellent uncorrected visual acuity at all distances. However, photic phenomena such as glare and halos are inherent to the design of these lenses and make preoperative patient councelling, careful case selection, and individualised weighing of benefits and side-effects important.

Multifocal IOLs (mIOLs) can provide excellent uncorrected visual acuity at all distances. However, photic phenomena such as glare and halos are inherent to the design of these lenses and make preoperative patient councelling, careful case selection, and individualised weighing of benefits and side-effects important.1,2

There are only two publications covering amblyopia and mIOL implantation. One group3 reported on 14 patients with amblyopia due to anisometropia (no strabismus, no microtropia) and implantation of a non-diffractive IOL (MPlus, Oculentis) with excellent subjective results, the second4 on three anisometropic amblyopic patients (one myopic, two hyperopic; one without cataract, two with cataract) without strabismus and implantation of a mIOL (AcrySof ReSTOR, Alcon) with a high patient satisfaction.

Our female patient (born in 1964) was hypermetropic, astigmatic and anisometropic since early childhood (right eye: +2.5 sph with -1,5 cyl/15°; left eye: +6.5 sph with -1.5 cyl/170°). She had a convergent squint of her left eye and was treated with occlusion foils on her spectacles and with four squint surgeries.

Her best corrected visual acuity was 1.25 in her right eye and 0.7 in her left eye. Contact lenses were not tolerated well. Presbyopia started to become a problem, so near-glasses with an addition of +1.75 D in both eyes were prescribed.

She wished to be spectacle-free and consulted an eye surgeon, who was willing to perform a Prelex, though she was informed that the visual acuity of her left eye would not improve. After informed consent and a trial with multifocal contact lenses (Acuvue multi, no troubles), toric trifocal intraocular lenses (Zeiss AT Lisa tri toric 939) were implanted in both eyes without any complications.

Postoperatively, the patient complained about halos, glare, waxy vision and double vision despite a visual acuity of 1.0 (right eye) and 0.6 (left eye) without correction. After an unsuccessful ‘neuronal adaption time’ she demanded explantation of both IOLs.

After informed consent, the right mIOL was explanted 5 months postoperatively, followed, 2 months later, by the left mIOL. In both eyes, monofocal toric IOLs were implanted in the capsular bag (Zeiss AT Torbi 709). Visual acuity was 1.0 (right eye) and 0.5 (left eye) postoperatively. Nevertheless, the complaints (halos, glare, waxy vision, etc.) remained and she sued the surgeon.

What might be the reasons for this unhappy course? When she had received her first glasses in early childhood with the high ansimetropia of about 4 D, her brain engrammed this specific size of pictures. Despite her (low grade) amblyopia, she had no central fixation, but a peripheral remaining binocular vision.

The mIOLs (with all their inherent disadvantages like decrease in contrast sensitivity and possible photic phenomena) reduced the refractive error of both eyes to zero, but a priori reduced contrast sensitivity in amblyopia and induced troubles with the size of both pictures. Furthermore, in the instructions for use of the multi- and monofocal IOL, amblyopia is listed as a severe contraindication for implantation in amblyopia!

So, always read the usage instructions for the type of the IOL you want to implant and perform a perfect orthopic status with explanation/interpretation before the surgery. Amblyopia is not a monocular disorder, and not simply a disorder of reduced visual acuity; it is an abnormal development of the binocular visual system affecting both eyes5.

References

1.       De Vries NE and Nuijts RMMA. Multifocal intraocular lenses in cataract surgery: Literature review of benefits and side effects. J Cataract Refract Surg. 2013;39:268-278.

2.       Braga-Mele R, et al. Multifocal intraocular lenses: Relative indications and contraindications for implantation. J Cataract Refract Surg. 2014; 40:313-323.

3.       De Wit DW, et al. Refractive lens exchange for a multifocal intraocular lens with a surface-embedded near section in mild to moderate anisometropic  amblyopic patients. J Cataract Refract Surg. 2012;38:1796-1801.

4.       Petermeier K, Gekeler F, Spitzer MS, Szurman P. Implantation of the multifocal ReSTOR apodised diffractive intraocular lens in adult anisometropic patients with mild to moderate amblyopia. Br J Ophthalmol. 2009; 93:1296.

5.       Meier K and Giaschi D. Unilateral amblyopia effects two eyes: Fellow eye deficits in amblyopia. Invest Ophthalmol Vis Sci. 2017;58:1779-1800.

 

E-mail: christoph.faschinger@meduni-graz.at

Dr Faschinger is a clinical professor at the Medical University of Graz, Clinic of Ophthalmology, Graz, Austria.