title: Investigation of the performance of the Menifocal Z gas-permeable bifocal contact lens during continuous wear.
abstract: OBJECTIVE
  The Menifocal Z is an alternating vision, concentric, bifocal gas-permeable (GP) contact lens; center distance is connected to near periphery by a smooth transition zone. The lens is produced using tisilfocon A (Menicon Z material), which is approved for up to 30 days of continuous wear (CW). The aim of this study was to evaluate the clinical performance of the Menifocal Z when worn for up to 30 days of CW for 6 months.
  
  
  METHODS
  Thirty-five existing GP lens wearers were enrolled in the study. Subjects were fitted with Menifocal Z lenses and follow-up visits were conducted after 2 weeks of daily wear and 1 day, 1 week, 6 weeks, 3 and 6 months of CW. A range of objective and subjective clinical performance measures were assessed, including distance and near visual acuity, the physiological response to CW, and subjective evaluation of vision and comfort.
  
  
  RESULTS
  Twenty-seven subjects (77%) completed the study and eight (23%) discontinued: five (14%) as a result of lens-related problems (four vision, one comfort) and three (9%) as a result of non-lens related reasons. Average CW time achieved by the subjects was 22 +/- 2 days. Mean binocular logarithm of the minimum angle of resolution (logMAR) acuities at 6 months were: high contrast distance 0.03 (20/20-), low contrast distance 0.63 (20/80-), and high contrast near 0.26 (20/25, N4). Adverse responses and lens binding were minimal, and there were no significant increases in corneal staining, corneal vascularization, or superior palpebral conjunctival papillae over time (p > 0.05). Problems with night vision (distance and near) with the lenses were the most common difficulties reported by the subjects.
  
  
  CONCLUSIONS
  The Menifocal Z appears to be a promising option for presbyopic vision correction, providing successful correction of distance and near vision in a group of experienced GP lens wearers. The hyper Dk tisilfocon A (Menicon Z) material allowed for safe wear of the lenses on a CW basis.
authors.affiliation: Clinical Vision Research Australia, Victorian College of Optometry, University of Melbourne.
authors.forename: Carol
authors.initials: C
authors.lastname: Lakkis
authors.forename: Silvia A
authors.initials: SA
authors.lastname: Goldenberg
authors.forename: Craig A
authors.initials: CA
authors.lastname: Woods
mesh_terms: D000328:Adult; D000368:Aged; D003262:Contact Lenses, Extended-Wear; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011305:Presbyopia / Q000503:physiopathology / Q000628:therapy*; D017755:Prosthesis Fitting; D012029:Refraction, Ocular; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity