MyopiaPhase 3NCT00000129
Prospective Evaluation of Radial Keratotomy (PERK) Study
A Phase 3 study testing Radial Keratotomy in people with Myopia, run by National Eye Institute (NEI).
Trial 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. Read more about this study
- Who is it for?
- Ages 21 years and older
- Conditions the study is for
- Myopia
- What is being tested?
- Radial Keratotomy
- Type of treatment
- Surgery or procedure
- How many people
- Not given
- Where
- No sites listed yet
- Study dates
- Apr 1981to Oct 1983
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
All men and women had 2 to 8 diopters of simple myopia and were correctable to 20/20 or better with glasses or contact lenses. All patients had the stability of their myopia documented by previous records. Patients were at least 21 years of age and lived in the metropolitan area of the study centers. Each patient agreed to have surgery on one eye and to wait 1 year for surgery on the other eye. Patients with systemic diseases that might affect corneal wound healing and patients with high corneal astigmatism were excluded from the study.
About this study
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.
Read the 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 patient's 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 (-2.00 to -3.12 D = 4.0 mm; -3.25 to -4.3 D = 3.5 mm; -4.50 to -8.00 D = 3.0 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-o'clock 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.
- Conditions
- Myopia
- Being tested
- Radial Keratotomy
- Medical subject headings
- Myopia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Radial KeratotomyProcedure or surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Sep 1999 (estimated)
- Study startApr 1981
- Study completionOct 1983
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (37)Papers the sponsor has linked to this study.
- Other trials for MyopiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
Sponsor and investigators
- Lead sponsor
- National Eye Institute (NEI)
- Sponsor type
- US National Institutes of Health
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00000129
- Sponsor's protocol ID
- NEI-28
- Status last verified
- Sep 2009
- First submitted
- 23 Sep 1999
- Last updated
- 17 Sep 2009
- Results posted
- No
Publications
Waring GO 3rd, Moffitt SD, Gelender H, Laibson PR, Lindstrom RL, Myers WD, Obstbaum SA, Rowsey JJ, Safir A, Schanzlin DJ, Bourque LB. Rationale for and design of the National Eye Institute Prospective Evaluation of Radial Keratotomy (PERK) Study. Ophthalmology. 1983 Jan;90(1):40-58. doi: 10.1016/s0161-6420(83)34603-0.
PubMed 6338438Bourque LB, Rubenstein R, Cosand B, Waring GO 3rd, Moffitt S, Gelender H, Laibson PR, Lindstrom RL, McDonald M, Myers WD, et al. Psychosocial characteristics of candidates for the prospective evaluation of radial keratotomy (PERK) study. Arch Ophthalmol. 1984 Aug;102(8):1187-92. doi: 10.1001/archopht.1984.01040030965027.
PubMed 6380467Novak AF; Lindstrom RL; Williams PA; Everson M; Corneal pachymetry prior to radial keratotomy: a comparison of techniques., J Refract Surg 1985;1:151-153
Steinberg EB, Waring GO 3rd. Comparison of two methods of marking the visual axis on the cornea during radial keratotomy. Am J Ophthalmol. 1983 Nov;96(5):605-8. doi: 10.1016/s0002-9394(14)73417-8.
PubMed 6638126Steinberg EB, Wilson LA, Waring GO 3rd, Lynn MJ, Coles WH. Stellate iron lines in the corneal epithelium after radial keratotomy. Am J Ophthalmol. 1984 Oct 15;98(4):416-21. doi: 10.1016/0002-9394(84)90122-3.
PubMed 6486212Nelson JD, Williams P, Lindstrom RL, Doughman DJ. Map-fingerprint-dot changes in the corneal epithelial basement membrane following radial keratotomy. Ophthalmology. 1985 Feb;92(2):199-205. doi: 10.1016/s0161-6420(85)34055-1.
PubMed 3872431Waring GO 3rd, Lynn MJ, Gelender H, Laibson PR, Lindstrom RL, Myers WD, Obstbaum SA, Rowsey JJ, McDonald MB, Schanzlin DJ, et al. Results of the prospective evaluation of radial keratotomy (PERK) study one year after surgery. Ophthalmology. 1985 Feb;92(2):177-98, 307. doi: 10.1016/s0161-6420(85)34054-x.
PubMed 3885128Atkin A, Asbell P, Justin N, Smith H, Wayne R, Winterkorn J. Radial keratotomy and glare effects on contrast sensitivity. Doc Ophthalmol. 1986 Feb 28;62(2):129-48. doi: 10.1007/BF00229125.
PubMed 3956364Bourque LB, Cosand BB, Drews C, Waring GO 3rd, Lynn M, Cartwright C. Reported satisfaction, fluctuation of vision, and glare among patients one year after surgery in the Prospective Evaluation of Radial Keratotomy (PERK) Study. Arch Ophthalmol. 1986 Mar;104(3):356-63. doi: 10.1001/archopht.1986.01050150056026.
PubMed 3954634Bourque LB; Cosand BB; Drews C; Waring GO; Lynn M; Cartwright C; Satisfaccion informada, fluctuacion de la vision y resplandor en pacientes al cabo de un ano tras la cirugia en el estudio de la evaluacion prospectiva de la queratotomia radial (EPQR)., Arch Ophthalmol 1986;2:57-64
Mandelbaum S, Waring GO 3rd, Forster RK, Culbertson WW, Rowsey JJ, Espinal ME. Late development of ulcerative keratitis in radial keratotomy scars. Arch Ophthalmol. 1986 Aug;104(8):1156-60. doi: 10.1001/archopht.1986.01050200062050.
PubMed 3741245Schanzlin DJ, Santos VR, Waring GO 3rd, Lynn M, Bourque L, Cantillo N, Edwards MA, Justin N, Reinig J, Roszka-Duggan V. Diurnal change in refraction, corneal curvature, visual acuity, and intraocular pressure after radial keratotomy in the PERK Study. Ophthalmology. 1986 Feb;93(2):167-75. doi: 10.1016/s0161-6420(86)33765-5.
PubMed 3951823Villasenor RA, Santos VR, Cox KC, Harris DF 2nd, Lynn M, Waring GO 3rd. Comparison of ultrasonic corneal thickness measurements before and during surgery in the prospective evaluation of Radial Keratotomy (PERK) Study. Ophthalmology. 1986 Mar;93(3):327-30. doi: 10.1016/s0161-6420(86)33746-1.
PubMed 3517739Lynn MJ; Waring GO; Predictability and stability of radial keratotomy., J. Refract Surg 1987;3:193-196
Lynn MJ, Waring GO 3rd, Sperduto RD. Factors affecting outcome and predictability of radial keratotomy in the PERK Study. Arch Ophthalmol. 1987 Jan;105(1):42-51. doi: 10.1001/archopht.1987.01060010048030.
PubMed 3800746
Study at a glance
From the registry record, last updated by the sponsor on 17 Sep 2009. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prospective Evaluation of Radial Keratotomy (PERK) Study
- ClinicalTrials.gov ID
- NCT00000129
- Acronym / sponsor ID
- NEI-28
- Conditions
- Myopia
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Completed
- Lead sponsor
- National Eye Institute (NEI)US National Institutes of Health
- Study start
- Apr 1981
- Study completion
- Oct 1983 (actual)
- First posted
- 24 Sep 1999 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 patient's 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 (-2.00 to -3.12 D = 4.0 mm; -3.25 to -4.3 D = 3.5 mm; -4.50 to -8.00 D = 3.0 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-o'clock 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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
Who may qualify
- Ages
- 21 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Radial Keratotomy | Procedure or surgery | – |
Primary outcome
Not reported in the source record.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Sep 2009.
- Background: PubMed 6338438Waring GO 3rd, Moffitt SD, Gelender H, Laibson PR, Lindstrom RL, Myers WD, Obstbaum SA, Rowsey JJ, Safir A, Schanzlin DJ, Bourque LB. Rationale for and design of the National Eye Institute Prospective Evaluation of Radial Keratotomy (PERK) Study. Ophthalmology. 1983 Jan;90(1):40-58. doi: 10.1016/s0161-6420(83)34603-0.
- Background: PubMed 6380467Bourque LB, Rubenstein R, Cosand B, Waring GO 3rd, Moffitt S, Gelender H, Laibson PR, Lindstrom RL, McDonald M, Myers WD, et al. Psychosocial characteristics of candidates for the prospective evaluation of radial keratotomy (PERK) study. Arch Ophthalmol. 1984 Aug;102(8):1187-92. doi: 10.1001/archopht.1984.01040030965027.
- BackgroundNovak AF; Lindstrom RL; Williams PA; Everson M; Corneal pachymetry prior to radial keratotomy: a comparison of techniques., J Refract Surg 1985;1:151-153
- Background: PubMed 6638126Steinberg EB, Waring GO 3rd. Comparison of two methods of marking the visual axis on the cornea during radial keratotomy. Am J Ophthalmol. 1983 Nov;96(5):605-8. doi: 10.1016/s0002-9394(14)73417-8.
- Background: PubMed 6486212Steinberg EB, Wilson LA, Waring GO 3rd, Lynn MJ, Coles WH. Stellate iron lines in the corneal epithelium after radial keratotomy. Am J Ophthalmol. 1984 Oct 15;98(4):416-21. doi: 10.1016/0002-9394(84)90122-3.
- Background: PubMed 3872431Nelson JD, Williams P, Lindstrom RL, Doughman DJ. Map-fingerprint-dot changes in the corneal epithelial basement membrane following radial keratotomy. Ophthalmology. 1985 Feb;92(2):199-205. doi: 10.1016/s0161-6420(85)34055-1.
- Background: PubMed 3885128Waring GO 3rd, Lynn MJ, Gelender H, Laibson PR, Lindstrom RL, Myers WD, Obstbaum SA, Rowsey JJ, McDonald MB, Schanzlin DJ, et al. Results of the prospective evaluation of radial keratotomy (PERK) study one year after surgery. Ophthalmology. 1985 Feb;92(2):177-98, 307. doi: 10.1016/s0161-6420(85)34054-x.
- Background: PubMed 3956364Atkin A, Asbell P, Justin N, Smith H, Wayne R, Winterkorn J. Radial keratotomy and glare effects on contrast sensitivity. Doc Ophthalmol. 1986 Feb 28;62(2):129-48. doi: 10.1007/BF00229125.
- Background: PubMed 3954634Bourque LB, Cosand BB, Drews C, Waring GO 3rd, Lynn M, Cartwright C. Reported satisfaction, fluctuation of vision, and glare among patients one year after surgery in the Prospective Evaluation of Radial Keratotomy (PERK) Study. Arch Ophthalmol. 1986 Mar;104(3):356-63. doi: 10.1001/archopht.1986.01050150056026.
- BackgroundBourque LB; Cosand BB; Drews C; Waring GO; Lynn M; Cartwright C; Satisfaccion informada, fluctuacion de la vision y resplandor en pacientes al cabo de un ano tras la cirugia en el estudio de la evaluacion prospectiva de la queratotomia radial (EPQR)., Arch Ophthalmol 1986;2:57-64
- Background: PubMed 3741245Mandelbaum S, Waring GO 3rd, Forster RK, Culbertson WW, Rowsey JJ, Espinal ME. Late development of ulcerative keratitis in radial keratotomy scars. Arch Ophthalmol. 1986 Aug;104(8):1156-60. doi: 10.1001/archopht.1986.01050200062050.
- Background: PubMed 3951823Schanzlin DJ, Santos VR, Waring GO 3rd, Lynn M, Bourque L, Cantillo N, Edwards MA, Justin N, Reinig J, Roszka-Duggan V. Diurnal change in refraction, corneal curvature, visual acuity, and intraocular pressure after radial keratotomy in the PERK Study. Ophthalmology. 1986 Feb;93(2):167-75. doi: 10.1016/s0161-6420(86)33765-5.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Radial Keratotomy in people with Myopia, run by National Eye Institute (NEI).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 17 Sep 2009. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT00000129, which also lists 37 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Sep 2009.