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

Study Description

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Brief Summary:

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 or disease	Intervention/treatment	Phase
Corneal Astigmatism	Procedure: Limbal relaxing incision	Not Applicable

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.

Study Design

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Study Type :	Interventional (Clinical Trial)
Estimated Enrollment :	30 participants
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
Study Start Date :	November 2006
Estimated Primary Completion Date :	December 2010
Estimated Study Completion Date :	December 2010

Arms and Interventions

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Outcome Measures

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Primary Outcome Measures :

1. Amount of surgically induced astigmatism at three months postop [ Time Frame: at three months postop ]

Secondary Outcome Measures :

1. Depth of LRI achieved at one month postop [ Time Frame: at one month postop ]
2. Unaided visual acuity at three months postop [ Time Frame: at three months postop ]

Eligibility Criteria

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

Criteria

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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Contacts

Contact: Wei Han Chua, FRCS Ophthalmology	+65 63228893	chua_wei_han@snec.com.sg

Locations

Singapore
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

Investigators

Principal Investigator:	Wei Han Chua, FRCS Ophthalmology	Singapore National Eye Centre

More Information

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Publications of Results:

Müller-Jensen K, Fischer P, Siepe U. Limbal relaxing incisions to correct astigmatism in clear corneal cataract surgery. J Refract Surg. 1999 Sep-Oct;15(5):586-9.

Gills JP. Treating astigmatism at the time of cataract surgery. Curr Opin Ophthalmol. 2002 Feb;13(1):2-6. Review.

Budak K, Friedman NJ, Koch DD. Limbal relaxing incisions with cataract surgery. J Cataract Refract Surg. 1998 Apr;24(4):503-8.

Responsible Party:	Dr Chua Wei Han, Singapore National Eye Centre
ClinicalTrials.gov Identifier:	NCT01122992 History of Changes
Other Study ID Numbers:	R489/38/2006
First Posted:	May 13, 2010
Last Update Posted:	May 13, 2010
Last Verified:	May 2010

Keywords provided by Singapore National Eye Centre:

Limbal relaxing incision; Astigmatic correction; Phacoemulsification surgery; Chinese eyes

Additional relevant MeSH terms:

Surgical Wound; Astigmatism; Wounds and Injuries; Refractive Errors; Eye Diseases