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A Clinical Study of Keratoconus in Asian Patients and Assessment of Different Topographic Patterns of Keratoconus in Asian Patients

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00347074
Recruitment Status : Completed
First Posted : July 4, 2006
Last Update Posted : July 7, 2006
Information provided by:
Singapore National Eye Centre

Brief Summary:
A clinical study of keratoconus in Asian Patients and assessment of different topographic patterns of keratoconus in Asian patients

Condition or disease

Detailed Description:

This hospital-based observational prospective study was designed to describe the characteristics of patients with keratoconus in an Asian population, Patients with keratoconus and keratoconus suspects presenting to the Singapore National Eye Centre who met the eligibility criteria are were recruited for this study. The following data were assessed:

  1. Demographic characteristics of patients with keratoconus
  2. Quality of life assessment in patients with keratoconus
  3. Visual Outcome and management of keratoconus in terms of contact lens fitting
  4. Corneal topographic patterns of patients with keratoconus
  5. Aberrometry studies with regards to diagnosis of keratoconus and quality of vision in patients with keratoconus.

The patients not wearing contact lenses completed the study within one visit whereas the patients wearing contact lenses required 2 visits (one with contact lens wear and one without contact lens wear) to complete the study. For patients wearing contact lenses, they were advised to stop soft or rigid contact lens wear for 3 days before the initial visual acuity, subjective refraction, keratometry, Tomey and Orbscan II topography examinations and Wavefront aberrometry tests were performed.

Informed consent was obtained from all subjects after the nature of the study had been fully explained. The study gained approval from the Ethics Committee of the Singapore Eye Research Institute .

Each study participant was asked to answer the demography questionnaire form regarding their daily habit, medical history, economic and educational level and vision-related quality of life, and the Visual Function Index (VF-14).

Visual acuity was assessed in each eye using a logMAR chart. The visual acuity with manifest refraction was deemed the best corrected visual acuity(BCVA) for those patients who did not wear contact lenses, and the visual acuity with over-refraction (refraction over their contact lenses) for contact lens wearers.

Contrast sensitivity was examined only in patients with their habitual contact lenses in each eye using the Vision Contrast Test System (VCTS) chart (VCTS 6500 contrast sensitivity Chart) in 6 spatial frequencies.

Slit lamp evaluation and contact lens fit assessment were performed. Type of contact lens wear was recorded.

Corneal topography was performed using Tomey keratoconus screening system (Topographic Modeling System, software version 2.4.2J) without pupil dilation and without contact lens wear and the Orbscan II corneal topography system (Bausch &Lomb Surgical).

Ocular wavefront aberrations were measured across the central 6-mm dilated pupil (1% Tropicamide) of each eye with the Bausch and Lomb Technolas Zywave aberrometer with Zywave software version 4.45 (ZYOPTIX Diagnostic Workstation, Bausch & Lomb).

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Study Type : Observational
Enrollment : 120 participants
Observational Model: Case-Control
Time Perspective: Other
Study Start Date : September 2003
Study Completion Date : March 2005

Resource links provided by the National Library of Medicine

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Patients with keratoconus and keratoconus suspect presenting to the Singapore National Eye Centre who are willing to participate in the study

Exclusion Criteria:

  • Patients with previous ocular surgery or trauma. Patients unwilling to participate in the study.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00347074

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Singapore National Eye Centre
Singapore, Singapore, 168751
Sponsors and Collaborators
Singapore National Eye Centre
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Principal Investigator: Li - Lim, FRCS(Ed) Singapore National Eye Centre

Layout table for additonal information Identifier: NCT00347074    
Other Study ID Numbers: R317/10/03
First Posted: July 4, 2006    Key Record Dates
Last Update Posted: July 7, 2006
Last Verified: September 2003
Keywords provided by Singapore National Eye Centre:
Keratoconus, corneal topography, ocular aberrometry, visual outcome, contact lens wear, quality of life
Additional relevant MeSH terms:
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Corneal Diseases
Eye Diseases