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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. The completion date has passed and the status has not been verified in more than two years.
Verified May 2010 by Singapore National Eye Centre.
Recruitment status was:  Recruiting
Information provided by:
Singapore National Eye Centre Identifier:
First received: May 11, 2010
Last updated: May 12, 2010
Last verified: May 2010
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.

Condition Intervention
Corneal Astigmatism Procedure: Limbal relaxing incision

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Prospective Evaluation of Limbal Relaxing Incision (LRI) in Conjunction With Phacoemulsification Surgery for Astigmatic Correction in Chinese Eyes

Further study details as provided by Singapore National Eye Centre:

Primary Outcome Measures:
  • Amount of surgically induced astigmatism at three months postop [ Time Frame: at three months postop ]

Secondary Outcome Measures:
  • 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 ]

Estimated Enrollment: 30
Study Start Date: November 2006
Estimated Study Completion Date: December 2010
Estimated Primary Completion Date: December 2010 (Final data collection date for primary outcome measure)
Detailed Description:

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.


Ages Eligible for Study:   21 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

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
  Contacts and Locations
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Please refer to this study by its identifier: NCT01122992

Contact: Wei Han Chua, FRCS Ophthalmology +65 63228893

Singapore National Eye Centre Recruiting
Singapore, Singapore, 168751
Principal Investigator: Zainah Alsagoff, FRCS Ophthalmology         
Sub-Investigator: Jocelyn chua, MRCS / MMED Ophthalmology         
Sponsors and Collaborators
Singapore National Eye Centre
Principal Investigator: Wei Han Chua, FRCS Ophthalmology Singapore National Eye Centre
  More Information

Responsible Party: Dr Chua Wei Han, Singapore National Eye Centre Identifier: NCT01122992     History of Changes
Other Study ID Numbers: R489/38/2006
Study First Received: May 11, 2010
Last Updated: May 12, 2010

Keywords provided by Singapore National Eye Centre:
Limbal relaxing incision
Astigmatic correction
Phacoemulsification surgery
Chinese eyes

Additional relevant MeSH terms:
Refractive Errors
Eye Diseases processed this record on August 23, 2017