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

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 Overview

• Status: Completed
• Conditions: Myopia

• Study Type: Observational
• Enrollment (Actual): 120

Contacts and Locations

Study Locations

• Singapore
  • Singapore, Singapore, 168751
    • Singapore National Eye Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 60 years (Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Myopic patients presenting to refractive service eligible for LASIK

Description

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.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
1 IntraLase flaps; Patients who have undergone flap creation with IntraLase laser
2 Visumax flaps; Patients who have undergone flaps created with Visumax laser

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Visual Acuity	3 months

Secondary Outcome Measures

Outcome Measure	Time Frame
complications	3 months
Subjective questionnaire	1 weekd
Corneal Sensation	3 months
Tear function	3 months
Wavefront analysis	3 months
Contrast Sensitivity	3 months

Collaborators and Investigators

• Sponsor: Singapore Eye Research Institute
• Investigators: Principal Investigator: Donald Tan, Singapore National Eye Centre

Publications and helpful links

General Publications

• D'Souza S, Petznick A, Tong L, Hall RC, Rosman M, Chan C, Koh SK, Beuerman RW, Zhou L, Mehta JS. Comparative analysis of two femtosecond LASIK platforms using iTRAQ quantitative proteomics. Invest Ophthalmol Vis Sci. 2014 May 6;55(6):3396-402. doi: 10.1167/iovs.14-14113.

Study record dates

Study Major Dates

• Study Start: January 1, 2010
• Primary Completion (Actual): August 1, 2012
• Study Completion (Actual): August 1, 2013

Study Registration Dates

• First Submitted: May 10, 2010
• First Submitted That Met QC Criteria: December 1, 2010
• First Posted (Estimated): December 3, 2010

Study Record Updates

• Last Update Posted (Actual): April 24, 2026
• Last Update Submitted That Met QC Criteria: April 22, 2026
• Last Verified: July 1, 2016

More Information

Terms related to this study

• Keywords: Myopia; Lasik; Femtosecond Laser; Visumax; IntraLase; Myopic Patients undergoing LASIK
• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Myopia
• Other Study ID Numbers: R683/33/2009; Other (Other Identifier: GENERATION HD2)