This site became the new on June 19th. Learn more.
Show more Menu IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu IMPORTANT: Talk with a trusted healthcare professional before volunteering for a study. Read more... Menu
Give us feedback

Comparison of Intralase and Visumax Femtosecond Laser for Laser In Situ Keratomileusis

This study has been completed.
Information provided by (Responsible Party):
Jodhbir Mehta, Singapore Eye Research Institute Identifier:
First received: May 10, 2010
Last updated: July 19, 2016
Last verified: July 2016
Emtosecond lasers are used in cutting the flap in LASIK procedures (laser corrective surgery for refractive error). Their use has decreased the incidence of serious complications when compared to the use of microkeratomes(mechanical blades). The commonest femtosecond laser currently used is 'Intralase'. A newer femtosecond laser 'Visumax' (Zeiss) is now available and differs from the Intralase in that it does not interfere with the curvature of the cornea when creating the flap. The Intralase applanates the cornea flat during flap creation which causes the intraocular pressure to be higher. Both Intralase and Visumax lasers are available to patients and surgeons to use at SNEC. The aim of the investigators study is to compare the two lasers in a randomization of left and right eyes in the same patient. The investigators want to measure any difference that the lower intraocular pressure may have during the creation of the flap. This will be measured with a questionaire on patient experience during the procedure and the outcomes of vision, refraction, contrast sensitivity, wave-front analysis, tear function,corneal sensation and flap thickness measured with anterior segment OCT during the post-operative follow up period. To date no-one has compared the use of these two femtosecond lasers. Both lasers are currently used clinically for flap creation at SNEC.


Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Prospective

Further study details as provided by Jodhbir Mehta, Singapore Eye Research Institute:

Primary Outcome Measures:
  • Visual Acuity [ Time Frame: 3 months ]

Secondary Outcome Measures:
  • complications [ Time Frame: 3 months ]
  • Subjective questionnaire [ Time Frame: 1 weekd ]
  • Corneal Sensation [ Time Frame: 3 months ]
  • Tear function [ Time Frame: 3 months ]
  • Wavefront analysis [ Time Frame: 3 months ]
  • Contrast Sensitivity [ Time Frame: 3 months ]

Enrollment: 45
Study Start Date: January 2010
Study Completion Date: August 2013
Primary Completion Date: August 2012 (Final data collection date for primary outcome measure)
1 IntraLase flaps
Patients who have undergone flap creation with IntraLase laser
2 Visumax flaps
Patients who have undergone flaps created with Visumax laser


Ages Eligible for Study:   21 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Myopic patients presenting to refractive service eligible for LASIK

Inclusion Criteria:

  • 21 years of age or older.
  • Cycloplegic spherical equivalent of >-1.00D
  • Refractive cylinder -4.00 D or less.
  • Best spectacle corrected visual acuity (BSCVA) of 6/12 or better in BOTH eyes.
  • Spherical or cylindrical error has progressed at -0.50D or less per year from date of baseline measurement.
  • Contact lens wearers must have removed contact lenses at least two (2) weeks before the baseline measurement.
  • No evidence of irregular astigmatism on corneal topography.
  • Available to attend post-operative examinations for a 3 month period.

Exclusion Criteria:

  • Progressive or unstable myopia and/or astigmatism.
  • Clinical or corneal topographic evidence of keratoconus.
  • Residual, recurrent or active ocular disease such as uveitis, severe dry eyes, severe allergic eye disease, glaucoma, visually significant cataract and retinal disease.
  • Previous corneal surgery or trauma within the corneal flap zone.
  • Patent corneal vascularization within 1mm of the corneal flap zone.
  • Taking systemic medications likely to affect wound healing, such as corticosteroids and antimetabolites.
  • Systemically immunocompromised.
  • Systemic disease likely to affect wound healing, such as diabetes, connective tissue disease and severe atopy.
  • Pregnant or nursing.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01252654

Singapore National Eye Centre
Singapore, Singapore, 168751
Sponsors and Collaborators
Singapore Eye Research Institute
Principal Investigator: Donald Tan Singapore National Eye Centre
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Jodhbir Mehta, Head Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute Identifier: NCT01252654     History of Changes
Other Study ID Numbers: R683/33/2009
Other ( Other Grant/Funding Number: [NMRC/TCR/002 - SERI/2008 - TCR 621/41/2008] )
Study First Received: May 10, 2010
Last Updated: July 19, 2016

Keywords provided by Jodhbir Mehta, Singapore Eye Research Institute:
Femtosecond Laser
Myopic Patients undergoing LASIK

Additional relevant MeSH terms:
Refractive Errors
Eye Diseases processed this record on September 21, 2017