title: Binocularity enhances visual acuity of eyes implanted with multifocal intraocular lenses.
abstract: OBJECTIVE
  To investigate the effect of binocularity on long-term visual acuity in patients who have undergone bilateral implantation of a presbyopia-correcting diffractive multifocal intraocular lens (IOL).
  
  
  METHODS
  Twenty patients (9 men and 11 women) with an average age of 70 ± 7 years (range: 56 to 78 years) underwent bilateral implantation of a diffractive multifocal IOL (AcrySof IQ ReSTOR IOL, SN60D3; Alcon Laboratories, Inc., Fort Worth, TX). Uncorrected visual acuity was measured monocularly and binocularly on average 26 ± 6 months following implantation in the second eye (range: 17 to 40 months) using the University of Crete European-wide modified Early Treatment Diabetic Retinopathy Study charts at the following distances: (1) 4 m, uncorrected distance visual acuity (UDVA), (2) 66 cm, uncorrected intermediate visual acuity (UIVA), and (3) 33 cm, uncorrected near visual (UNVA).
  
  
  RESULTS
  Mean ± standard deviation UDVA was 0.07 ± 0.10 and 0.21 ± 0.12 logMAR (20/23 and 20/32 Snellen) in the better and worse eye, respectively, improving to 0.00 ± 0.09 logMAR (20/20 Snellen) binocularly. Mean ± standard deviation UIVA was 0.18 ± 0.14 and 0.32 ± 0.15 logMAR (20/30 and 20/42 Snellen) in the better and worse eye, respectively, improving to 0.08 ± 0.15 logMAR (20/24 Snellen) binocularly. Mean ± standard deviation UNVA was 0.20 ± 0.09 and 0.32 ± 0.12 logMAR (20/32 and 20/42 Snellen) in the better and worse eye, respectively, improving to 0.11 ± 0.10 logMAR (20/26 Snellen) binocularly. Binocular summation, defined as the difference between the binocular and better eye visual acuity, was found to be statistically significant at all distances: 0.07 ± 0.05 logMAR at 4 m, 0.10 ± 0.11 logMAR at 66 cm, and 0.09 ± 0.08 logMAR at 33 cm.
  
  
  CONCLUSIONS
  The results confirm that there is substantial benefit of binocular vision in individuals with bilateral multifocal IOL implantation in terms of increased visual acuity. This effect is evident at all distances.
authors.affiliation: 2nd Ophthalmology Department, Aristotle University of Thessaloniki, Papageorgiou General Hospital, Thessaloniki, Greece.
authors.forename: Konstantinos T
authors.initials: KT
authors.lastname: Tsaousis
authors.forename: Sotiris
authors.initials: S
authors.lastname: Plainis
authors.forename: Stavros A
authors.initials: SA
authors.lastname: Dimitrakos
authors.forename: Ioannis T
authors.initials: IT
authors.lastname: Tsinopoulos
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D011305:Presbyopia / Q000503:physiopathology / Q000601:surgery*; D011474:Prosthesis Design; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*