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

November 21, 2007
November 26, 2007
July 7, 2010
October 2004
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final refraction deviation from target [ Time Frame: 1 and 3 months post cataract operation ]
Same as current
Complete list of historical versions of study NCT00563277 on Archive Site
change of IOL power from pre-pterygium estimated power [ Time Frame: 1 and 3 months post pterygium excision ]
Same as current
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Surgical Treatment of Concurrent Cataract and Primary Pterygium
Surgical Treatment of Concurrent Cataract and Primary Pterygium: A Randomized Control Trial

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.

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Not Applicable
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
  • Pterygium
  • Cataract
  • Lenses, Intraocular
  • Procedure: combined pterygium and cataract operation
  • Procedure: pterygium excision followed by cataract operation
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*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Unknown status
Same as current
December 2006
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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
Sexes Eligible for Study: All
18 Years and older   (Adult, Senior)
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Contact information is only displayed when the study is recruiting subjects
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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
Hospital Authority, Hong Kong
July 2010

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP