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

NCT ID: NCT01122992

Last Updated: 2010-05-13

Basic Information

• Recruitment Status: UNKNOWN
• Clinical Phase: NA
• Total Enrollment: 30 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2006-11-30
• Study Completion Date: 2010-12-31

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.

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.

Conditions

Corneal Astigmatism

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Interventions

Limbal relaxing incision

Intervention Type: PROCEDURE

Eligibility 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

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

• Minimum Eligible Age: 21 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Singapore National Eye Centre

OTHER_GOV

Sponsor Role: lead

Responsible Party

Singapore National Eye Centre

Principal Investigators

Wei Han Chua, FRCS Ophthalmology

Role: PRINCIPAL_INVESTIGATOR

Singapore National Eye Centre

Locations

Singapore National Eye Centre

Singapore, , Singapore

Site Status: RECRUITING

Countries

Singapore

Central Contacts

Wei Han Chua, FRCS Ophthalmology

Role: CONTACT

chua_wei_han@snec.com.sg

+65 63228893

References

Muller-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. doi: 10.3928/1081-597X-19990901-12.

Reference Type: RESULT

PMID: 10504084 (View on PubMed)

Gills JP. Treating astigmatism at the time of cataract surgery. Curr Opin Ophthalmol. 2002 Feb;13(1):2-6. doi: 10.1097/00055735-200202000-00002.

Reference Type: RESULT

PMID: 11807381 (View on PubMed)

Budak K, Friedman NJ, Koch DD. Limbal relaxing incisions with cataract surgery. J Cataract Refract Surg. 1998 Apr;24(4):503-8. doi: 10.1016/s0886-3350(98)80292-7.

Reference Type: RESULT

PMID: 9584246 (View on PubMed)

Other Identifiers

R489/38/2006

Identifier Type: -

Identifier Source: org_study_id