Ignite Creation Date:
2024-05-05 @ 9:42 AM
Last Modification Date:
2024-10-26 @ 9:01 AM
Study NCT ID:
NCT00000129
Status:
COMPLETED
Last Update Posted:
2009-09-17
First Post:
1999-09-23
Brief Title:
Prospective Evaluation of Radial Keratotomy PERK Study
Sponsor:
National Eye Institute NEI
Organization:
National Eye Institute NEI
Study Overview
Official Title:
None
Status:
COMPLETED
Status Verified Date:
2009-09
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
To determine whether radial keratotomy is effective in reducing myopia
To detect complications of the surgery
To discover patient characteristics and surgical factors affecting the results
To determine the long-term safety and efficacy of the procedure
To detect complications of the surgery
To discover patient characteristics and surgical factors affecting the results
To determine the long-term safety and efficacy of the procedure
Detailed Description:
Approximately 11 million Americans have myopia that can be corrected with eyeglasses or contact lenses Some of these people may also be candidates for radial keratotomy RK a procedure that aims to correct or reduce myopia by surgery that flattens the corneal curvature
Keratotomy was first performed by surgeons in Europe and the United States in the late 1800s and the basic optical and mechanical principles of the operation were defined in the 1940s and 1950s by the Japanese doctors T Sato and K Akiyama who used anterior and posterior corneal incisions The posterior incisions damaged the cornea and the procedure was modified in the Soviet Union by doctors Fyodorov and V Durnev to include incisions in only the anterior cornea Since its introduction into the United States in 1978 numerous ophthalmologists have modified the procedure by introducing technical and surgical improvements such as ultrasonic methods to measure the thickness of the cornea and the use of diamond-bladed micrometer knives to make the incisions
However scientific assessment of RK lagged behind growing public and professional interest in the procedure In 1980 in response to widespread concern about the long-term safety and efficacy of RK a group of ophthalmic surgeons approached the National Eye Institute with a proposal for a multicenter clinical trial that would evaluate the potential benefits and risks of this procedure
The Prospective Evaluation of Radial Keratotomy study involving 435 patients and 99 pilot patients was a clinical trial designed to evaluate the short- and long-term safety and efficacy of one technique of radial keratotomy The procedure was evaluated by comparing a patients refractive error and uncorrected vision before and after surgery The more myopic eye received surgery first Patients were required to wait 1 year before having the operation on the second eye
The surgical technique was standardized consisting of eight centrifugal radial incisions made manually with a diamond micrometer knife The diameter of the central uncut clear zone was determined by the preoperative spherical equivalent cycloplegic refraction -200 to -312 D 40 mm -325 to -43 D 35 mm -450 to -800 D 30 mm The blade length which determined the depth of the incision was set at 100 percent of the thinnest of four intraoperative ultrasonic corneal thickness readings taken paracentrally at the 3- 6- 9- and 12-oclock meridians just outside the mark delineating the clear zone The incisions were made from the edge of the trephine mark to the limbal vascular arcade and were spaced equidistantly around the cornea
Patients were examined preoperatively and after surgery at 2 weeks 3 months 6 months annually for 5 years and at 10 years Examinations in the morning and evening of the same day were done at 3 months 1 year 3 years and 11 years in a subset of the patients to test for diurnal fluctuation of vision and refraction
The primary outcome variables measured at each visit was the uncorrected and spectacle-corrected visual acuity and the refractive error with the pupil dilated and undilated The corneal shape was measured with central keratometry and photokeratoscopy Endothelial function was evaluated using specular microscopy A slit-lamp microscope examination was made to check for complications from the incisions Contrast sensitivity was tested in a subset of patients Patient motivation and satisfaction were studied with psychometric questionnaires at baseline 1 year 5-6 years and 10 years
Keratotomy was first performed by surgeons in Europe and the United States in the late 1800s and the basic optical and mechanical principles of the operation were defined in the 1940s and 1950s by the Japanese doctors T Sato and K Akiyama who used anterior and posterior corneal incisions The posterior incisions damaged the cornea and the procedure was modified in the Soviet Union by doctors Fyodorov and V Durnev to include incisions in only the anterior cornea Since its introduction into the United States in 1978 numerous ophthalmologists have modified the procedure by introducing technical and surgical improvements such as ultrasonic methods to measure the thickness of the cornea and the use of diamond-bladed micrometer knives to make the incisions
However scientific assessment of RK lagged behind growing public and professional interest in the procedure In 1980 in response to widespread concern about the long-term safety and efficacy of RK a group of ophthalmic surgeons approached the National Eye Institute with a proposal for a multicenter clinical trial that would evaluate the potential benefits and risks of this procedure
The Prospective Evaluation of Radial Keratotomy study involving 435 patients and 99 pilot patients was a clinical trial designed to evaluate the short- and long-term safety and efficacy of one technique of radial keratotomy The procedure was evaluated by comparing a patients refractive error and uncorrected vision before and after surgery The more myopic eye received surgery first Patients were required to wait 1 year before having the operation on the second eye
The surgical technique was standardized consisting of eight centrifugal radial incisions made manually with a diamond micrometer knife The diameter of the central uncut clear zone was determined by the preoperative spherical equivalent cycloplegic refraction -200 to -312 D 40 mm -325 to -43 D 35 mm -450 to -800 D 30 mm The blade length which determined the depth of the incision was set at 100 percent of the thinnest of four intraoperative ultrasonic corneal thickness readings taken paracentrally at the 3- 6- 9- and 12-oclock meridians just outside the mark delineating the clear zone The incisions were made from the edge of the trephine mark to the limbal vascular arcade and were spaced equidistantly around the cornea
Patients were examined preoperatively and after surgery at 2 weeks 3 months 6 months annually for 5 years and at 10 years Examinations in the morning and evening of the same day were done at 3 months 1 year 3 years and 11 years in a subset of the patients to test for diurnal fluctuation of vision and refraction
The primary outcome variables measured at each visit was the uncorrected and spectacle-corrected visual acuity and the refractive error with the pupil dilated and undilated The corneal shape was measured with central keratometry and photokeratoscopy Endothelial function was evaluated using specular microscopy A slit-lamp microscope examination was made to check for complications from the incisions Contrast sensitivity was tested in a subset of patients Patient motivation and satisfaction were studied with psychometric questionnaires at baseline 1 year 5-6 years and 10 years
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None