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Prospective Evaluation of Limbal Relaxing Incision (LRI) in Conjunction With Phacoemulsification Surgery for Astigmatic Correction in Chinese Eyes

The recruitment status of this study is unknown because the information has not been verified recently.
Verified May 2010 by Singapore National Eye Centre.
Recruitment status was  Recruiting
Sponsor:
Information provided by:
Singapore National Eye Centre
ClinicalTrials.gov Identifier:
NCT01122992
First received: May 11, 2010
Last updated: May 12, 2010
Last verified: May 2010

May 11, 2010
May 12, 2010
November 2006
December 2010   (final data collection date for primary outcome measure)
Amount of surgically induced astigmatism at three months postop [ Time Frame: at three months postop ]
Same as current
Complete list of historical versions of study NCT01122992 on ClinicalTrials.gov Archive Site
  • Depth of LRI achieved at one month postop [ Time Frame: at one month postop ]
  • Unaided visual acuity at three months postop [ Time Frame: at three months postop ]
Same as current
Not Provided
Not Provided
 
Prospective Evaluation of Limbal Relaxing Incision (LRI) in Conjunction With Phacoemulsification Surgery for Astigmatic Correction in Chinese Eyes
Prospective Evaluation of Limbal Relaxing Incision (LRI) in Conjunction With Phacoemulsification Surgery for Astigmatic Correction in Chinese Eyes

The main purpose of this study is to evaluate the use of limbal relaxing incision (LRI) for astigmatic correction. LRI is a procedure where a pair of incisions is made in the peripheral part of the cornea so as to alter its shape and improve the focusing power of the eye.

An important aim in cataract surgery has always been a good postoperative visual outcome. Efforts have been made to achieve this, with the introduction of intraocular lens in the 1980s and small incision cataract surgery in the 1990s. In the recent years, 'refractive' cataract surgery has taken the form of corneal astigmatic correction. Patients with pre-existing astigmatism of more than 1.5D may benefit from surgical correction during cataract surgery, in the hope of improving uncorrected visual acuity as well as lesser image distortion from corneal aberrations.

The limbal relaxing incisional technique involves placement of incisions corresponding to the steep meridian, thereby resulting in corneal flattening and reduction of astigmatic power. It is increasingly popular due to its advantages. LRI is simple to perform, very safe procedure in experienced hands, effective for astigmatic reduction of up to 4D, has rapid visual rehabilitation and is associated with very few visual complications due to the peripheral location of the incisions. Possible complications include globe weakening, corneal perforation, worsening of astigmatism, incorrect incisional placement and corneal hypoesthesia.

LRI technique and the practical nomograms has been described and made feasible by both James P Gills and Louis D Nichamin. Based on preoperatively measured astigmatic power and axis, these two nomograms recommend a systematic approach to the amount of surgical correction required.

The reason for the Nichamin nomogram being more frequently applied, can be attributed to a few inherent features. It accounts for the age of the patient as a surgical variability and recommends the use of paired arcuate limbal incisions measured in degrees of arc. Paired incisions enable symmetric corneal flattening at the steep meridian, whilst arcuate incisions are more physiological, thereby resulting in accurate astigmatic correction that is independent of corneal diameter. Nichamin has also implemented a modified Nichamin age and pachymetry-adjusted nomogram (otherwise known as 'NAPA' nomogram). It accounts for the patient's peripheral corneal thickness and adjusts the incisional depth accordingly to achieve 90% of corneal thickness.

Many studies have shown that LRI is an effective option for astigmatic correction in Caucasian eyes. Whether these results can be further extrapolated to apply to Chinese eyes are still largely uncertain. To date, there has not been a formal study conducted to evaluate this hypothesis. Moreover, there has been some anecdotal evidence suggesting less favorable postoperative outcome of LRI in Chinese eyes. The main objective of our study is thus to assess the utility and effectiveness of LRI in Chinese eyes.

Interventional
Not Provided
Allocation: Non-Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
Corneal Astigmatism
Procedure: Limbal relaxing incision
Not Provided

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruiting
30
December 2010
December 2010   (final data collection date for primary outcome measure)

Inclusion Criteria:

  • Study subjects should be at least 21 years old, and not older than 60 years old
  • Only Chinese patients will be eligible for this study
  • Presence of a pre-existing regular astigmatism ranging between -1.00 to -3.00D
  • Informed consent obtained for both phacoemulsification surgery and LRI procedure
  • Study subject is agreeable to comply with the postoperative follow-up regime stated
  • Absence of any exclusion criteria

Exclusion Criteria:

  • Presence of irregular astigmatism
  • Pre-existing pterygium
  • Previous corneal / anterior segment surgery
  • Pre-existing corneal scar
  • Pre-existing corneal pathology eg keratoconus, Fuch's endothelial dystrophy, PUK, etc
  • Pre-existing glaucoma
Both
21 Years to 60 Years
Yes
Contact: Wei Han Chua, FRCS Ophthalmology +65 63228893 chua_wei_han@snec.com.sg
Singapore
 
NCT01122992
R489/38/2006
Not Provided
Dr Chua Wei Han, Singapore National Eye Centre
Singapore National Eye Centre
Not Provided
Principal Investigator: Wei Han Chua, FRCS Ophthalmology Singapore National Eye Centre
Singapore National Eye Centre
May 2010

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