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Surgical Treatment of Concurrent Cataract and Primary Pterygium

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: NCT00563277
Recruitment Status : Unknown
Verified July 2010 by Hospital Authority, Hong Kong.
Recruitment status was:  Recruiting
First Posted : November 26, 2007
Last Update Posted : July 7, 2010
Information provided by:
Hospital Authority, Hong Kong

Brief Summary:

Pterygium is known to induce with-the-rule astigmatism. The corneal curvature along the long axis of the pterygium body is flattened. The excision of pterygium will result in steepening of the cornea and reduction of astigmatism. Therefore, the effect of pterygium excision on intraocular lens (IOL) power calculation has been examined in our previous study. The study confirmed that pterygium can cause alteration of IOL power.

The determination of IOL power for cataract surgery is usually calculated from IOL formula called SRK II formula. IOL power = A - (2.5 x AL)-(0.9 x K). Variable A denotes the A-constant of the intraocular lens which is dependent on the IOL material and refractive index. Other variables for input include axial length (AL) and keratometry (K). A larger K reading will result in a lower estimated IOL power and vice versa. Previous studies have documented simultaneous cataract and pterygium operation resulted in reasonable visual outcome without adjustment of IOL power.

With the presence of a pterygium, the cornea is flattened and lead to a reduction of K value and over-estimation of calculated IOL power. This randomized controlled trial is designed to compare the refractive outcomes of sequential and simultaneous pterygium and cataract operation.

Pterygium excision should be done with various adjuvant therapies to minimize recurrence. Our previous studies reliably demonstrated limbal conjunctival graft and mitomycin C were effective methods to achieve low pterygium recurrence. We use limbal conjunctival autograft as the adjuvant therapy in the current study because this method is safer to be performed either alone or in combination with phacoemulsification. We avoid using mitomycin C as the adjuvant therapy in order to minimize the possibility of intraocular toxicity due to seepage.

Condition or disease Intervention/treatment Phase
Pterygium Cataract Lenses, Intraocular Procedure: combined pterygium and cataract operation Procedure: pterygium excision followed by cataract operation Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 75 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Surgical Treatment of Concurrent Cataract and Primary Pterygium: A Randomized Control Trial
Study Start Date : October 2004
Estimated Study Completion Date : December 2006

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Cataract

Primary Outcome Measures :
  1. final refraction deviation from target [ Time Frame: 1 and 3 months post cataract operation ]

Secondary Outcome Measures :
  1. change of IOL power from pre-pterygium estimated power [ Time Frame: 1 and 3 months post pterygium excision ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All

Inclusion Criteria:

  • >18 years old
  • Primary pterygium > 2mm across corneal limbus [Measurement made from the imaginary line of surgical limbus to the most advance edge of the visible pterygium tissue] Concurrent visually significant cataract ( BCVA < 20/70 )
  • Informed consent for both pterygium and cataract surgery

Exclusion Criteria:

  • Temporal pterygium
  • Double headed pterygium
  • Previous ocular surgery in which conjunctival-limbal graft is not feasible
  • Pterygium covering visual axis that preclude keratometric assessment
  • History of scleritis or autoimmune diseases

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): NCT00563277

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Contact: Lulu Cheng, Dr (852) 2632 2878

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Alice Ho Miu Ling Nethersole Hospital Recruiting
Hong Kong, China
Hong Kong Eye Hospital Recruiting
Hong Kong, China
Sub-Investigator: Dennis Lam, Prof         
Prince of Wales Hospital Recruiting
Hong Kong, China
Sub-Investigator: Alvin Young, Dr         
Sub-Investigator: Gloria Leung, Dr         
Sub-Investigator: Arthur Cheng, Prof         
Sponsors and Collaborators
Hospital Authority, Hong Kong
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Principal Investigator: Lulu Cheng, Dr Department of DOVS, Prince of Wales Hospital/ The Chinese University of Hong Kong
Additional Information:
Layout table for additonal information Identifier: NCT00563277    
Other Study ID Numbers: CRE-2004.274-T
First Posted: November 26, 2007    Key Record Dates
Last Update Posted: July 7, 2010
Last Verified: July 2010
Keywords provided by Hospital Authority, Hong Kong:
Intraocular lens power calculation accuracy
Additional relevant MeSH terms:
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Lens Diseases
Eye Diseases
Conjunctival Diseases