Over the last few years the expectations of cataract patients have increased and today more than 90% of them express a wish to be spectacles-free after surgery.

Today, to achieve this result surgeons have three different options open to them: multifocal IOLs, accomodative IOLs and monovision. Even if multifocal and accomodative IOLs represent a great step forward we seem to be far from providing the final solution for a number of different reasons.

Subsequently, the interest in monovision has increased during the last few months.

Ocular dominance represents an important factor in the overall success of monovision so that commonly the dominant eye is focused for distance vision and the non-dominant eye is focused for near to intermediate vision, because correcting the dominant eye for the most commonly used viewing distance maximizes blur suppression.^1–3

However, more important seems to be the magnitude of ocular dominance. In fact, for successful monovision, interocular blur suppression should flexibly alter in each eye at any distance.^3,4

Our study

We conducted a study to evaluate visual performance and satisfaction in cataract patients in whom we have applied different options to correct presbyopia.

A group of 25 patients with pseudophakic monovision (target refraction: emmetropia in the dominant eye and –1.50 D in the non-dominant eye) have been compared with a group of 25 patients with a bilateral implantation of a multifocal IOL.

The dominant eye has been determined simply asking the patients to view a distant target throught a circle made by thumb and forefinger.

In the monovision group an aspheric acrylic hydrophobic lens (Tecnis AMO Abbott Laboratories?Inc. Abbott Park, Illinois, USA) was implanted in both eyes and in the multifocal group an aspheric multifocal acrylic hydrophobic lens (Tecnis Multifocal AMO Abbott Laboratories Inc.).

In this study we evaluated at a three month follow-up: near and distant uncorrected visual acuity; contrast sensitivity in scotopic conditions; spectacle independence; patient satisfaction index; reading speed.

Results

Figure 1

Uncorrected binocular distance visual acuity was better than 20/40 in 100% of patients of both the groups and 20/20 in 83% of the monovision patients group and 76% in the multifocal implanted patients group (Figure 1).

Figure 2

Also uncorrected binocular near visual acuity was better in the monovision group (Figure 2).

Figure 3

In order to evaluate patient satisfaction the modified VF-7 questionnaire was applied and we obtained a higher rate of satisfaction in the monovision group (Figure 3).

Figure 4

To be specific 80% of the monovision patients achieved complete spectacle independence against 62% of patients who had received a multifocal implant (Figure 4).

Figure 5

The reading speed, evaluated with the 'Slow-fast reading test,' developed by Dr Giardini, did not present a significant statistical difference in the two groups (Figure 6). Also the contrast sensitivity in mesopic conditions of illumination evaluated with the FACT (functional acuity contrast test) has proven better results in the monovision group (Figure 5).