Bilateral cataract monovision surgery in a 54-year-old woman following Presbyond laser-blended vision: A case report

INTRODUCTION

Presbyond laser-blended vision (LBV) is a presbyopia treatment option from Zeiss (Carl Zeiss Meditec, Germany) which uses a combination of monovision and induction of spherical aberration, which leads to an increase in the depth of focus. This results in spectacle independence binocularly for all distances.^[1]

These patients eventually require cataract surgery and care should be taken so that the benefit of LBV induced by Presbyond is carried forward after cataract surgery by preserving the induced spherical aberrations. This will ensure that the patient will continue to remain spectacle-independent at distance, intermediate and near vision binocularly.

CASE REPORT

A 54-year-old woman presented with a gradual diminution of vision in both eyes for 2 years. She gives a history of undergoing Presbyond LBV 5 years back. Unaided distance visual acuity was 20/40 OU with no improvement and uncorrected near visual acuity was N18 in OD and N5 in OS, binocularly reading N5. Measurement of visual acuity was done using early treatment diabetic retinopathy study (ETDRS) charts (Precision Vision, La Sella, IL, USA). OD was dominant. Intraocular pressures recorded with non-contact tonometry (NCT) (Tomey NCT, NishiKu, Nagoya, Japan) was 12 mm Hg in both eyes. A gonioscopy revealed open angles in both eyes. The Z (4.0) of spherical aberration in OD was −0.613 um, and in OS, it was 0.483 um.

On examination, the patient was orthophoric on a cover test, extraocular movements were full and free and with a well-dilating pupil in both eyes (8 mm). Corneal topography (Pentacam HR, Oculus, Wetzlar, Germany) revealed K1: 44.30 D, K2: 44.80 D in OD and K1: 46.4, K2: 47.0 D in OS with myopic pattern post refractive surgery topography. Anterior chamber depth was 3.5 mm OD, 3.68 mm OS. White-to-white measurement was 12.6 mm OD and 12.7 mm in OS, measured using Scheimpflug technology (Pentacam HR, Oculus, Wetzlar, Germany) [Figure 1]. On examination of the anterior segment, both eyes’ cornea showed a clear interface with an 8 mm Femto Lasik scar, with posterior subcapsular cataract and nuclear sclerosis grade 1. A dilated fundus examination revealed normal fundus. Keeping her previous corneal procedure in mind, a monovision cataract surgery with an aspheric intraocular lens (IOL) was planned to achieve vision for near, intermediate, and distance and not to induce new aberrations.

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Figure 1:

Pre-operative Scheimpflug imaging showing corneal topography after Presbyond in the right eye and left eye. OD: Oculus dexter, OS: Oculus sinister.

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IOL power calculations were done using optical biometry (IOL Master 700-Carl Zeiss Meditec, Jena, Germany). Formulae used were – Barrett’s TK Universal II, Barrett’s True-K, Barrett’s True-K total keratometry (TK), Haigis-L, Holladay-2 with equivalent keratometry reading (EKR) and ray trace, which gave variable refractive outcomes. The IOL power calculated by Barrett TK Universal II/Barrett’s True-K TK was used.^[2] The IOL power was +24.0 D in OD and +22.50 D in OS. A monofocal aspheric IOL was used (Zeiss CT Lucia 621) [Table 1]. OS was operated first followed by OD. Routine phacoemulsification surgery was done using a 2.8 mm incision. The procedure was uneventful for both eyes. At postoperative day 15, no complications were noted. Binocularly, the patient maintained a corrected distance visual acuity of 20/20 through the 6-month follow-up period [Table 2].

Binocular defocus curves were plotted with distance correction from + 3.00 to − 3.00 D. The curve showed two peaks at −0.50 D and +0.5D, corresponding to a visual acuity of 0.0 logarithm of the minimum angle of resolution (logMAR), followed by a gradual decline. A mean visual acuity of 0.0 log MAR or better was observed within the defocus range of −0.5 to + 0.50 D, and a full range of functional vision, that is, 0.2 logMAR (20/30) or better, was achieved from + 0.50 to −1.00 D of defocus [Figure 2].

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Figure 2:

Defocus curve. CDVA: Corrected distance visual acuity.

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Using the Salzburg reading desk, the patient’s reading performance was evaluated. She was able to read 162 words/min at a distance of 40 cm and 164 words/min at 66 cm, signifying a comfortable reading at both 40 and 66 cm post-monovision cataract surgery.

DISCUSSION

Surgical correction of presbyopia with Presbyond is an advanced technique used by refractive surgeons worldwide. This patient has been comfortable with LBV for 5 years; therefore, the same design of cataract surgery should be taken into consideration.

In this case, we have used the Barrett TK/True-K TK formula which was more accurate compared to other popular post-refractive surgery formulas. It has been improved using historical data and measured posterior corneal power.^[3-5]

With the use of aspheric monofocal IOLs to retain the Presbyond ‘blended vision’, not only are the photopic phenomena associated with multifocal IOLs minimised, but a larger number of patients can be considered as potential candidates.^[6] EDOF IOLs are not suitable for patients with a history of Presbyond as they induce spherical aberrations. This will no longer have the benefit of the induced spherical aberrations by Presbyond, causing a drop in visual acuity. A potential disadvantage is a decrease in retinal image quality if the amount of aberrations is excessively increased.^[7]

CONCLUSION

The technique of monovision has been in use for years, whether with contact lenses, corneal refractive surgery or pseudophakia. In this case, it helped the patient in achieving near-, intermediate-, and distant vision without any spectacles. Since this patient had already undergone a corneal refractive procedure using the LBV technique, doing cataract surgery using monofocal aspheric IOL, which does not induce spherical aberration, was found feasible and accurate than any other lenses achieving good intermediate vision along with good distance and near vision. Appropriate IOL power calculation formula for the calculation of lens power should be used in such cases status post-refractive surgery. In this case, it was achieved using Barrett’s TK universal II/True-K TK formula.