[Skip to Content]
Access to paid content on this site is currently suspended due to excessive activity being detected from your IP address 54.158.169.168. Please contact the publisher to request reinstatement.
[Skip to Content Landing]
Article
January 1987

Factors Affecting Outcome and Predictability of Radial Keratotomy in the PERK Study

Author Affiliations

From the PERK Coordinating Center, Emory University, Atlanta.

Arch Ophthalmol. 1987;105(1):42-51. doi:10.1001/archopht.1987.01060010048030
Abstract

• The Prospective Evaluation of Radial Keratotomy (PERK) study used a standardized surgical technique that included a central clear zone with a diameter of 4.0, 3.5, or 3.0 mm. Multiple regression analysis of the outcome in one eye from each of 411 patients disclosed that the diameter of the central clear zone, patient age, and depth of the incision scar were the major factors affecting the change in refraction one year after surgery. Preoperative factors examined that did not have a significant influence on the outcome were sex, average central keratometric power, corneal thickness, corneal diameter, intraocular pressure, and ocular rigidity. The predictability of radial keratotomy, ie, the precision with which the outcome can be estimated, was measured by the 90% confidence interval for the change in refraction based on the regression equation. The width of this interval within each clear zone group was as follows: 4.0 mm, 2.49 diopters; 3.5 mm, 3.38 D; 3.0 mm, 4.12 D. For all 411 eyes, the 90% confidence interval was approximately 3.50 D wide. Thus, the surgeon could be 90% certain that an individual patient's refraction would be within 1.75 D of the predicted value one year after surgery.

References
1.
Fyodorov SN:  Methods of radial keratotomy , in Schachar RA, Levy NS, Schachar L (eds): Radial Keratotomy . Denison, Tex, LAL Publishing, 1980, pp 35-66.
2.
Knauss W, Rapacz P, Sene K, et al:  Curvature changes induced by radial keratotomy in solithane model of eye . Invest Ophthalmol Vis Sci 1982;20( (suppl) ):69.
3.
Schachar R, Black T, Huang T: Understanding Radial Keratotomy . Denison, Tex, LAL Publishing, 1981, pp 12-37.
4.
Salz JJ, Rowsey JJ, Caroline P, et al:  A study of optical zone size and incision redeepening in experimental radial keratotomy . Arch Ophthalmol 1985;103:590-594.Article
5.
Salz JJ, Lee T, Jester JV, et al:  Analysis of incision depth following experimental radial keratotomy . Ophthalmology 1983;90:655-659.Article
6.
Jester JV, Venet T, Lee J, et al:  A statistical analysis of radial keratotomy in human cadaver eyes . Am J Ophthalmol 1981;92:172-177.
7.
Salz JJ, Lee J, Jester JV, et al:  Radial keratotomy in fresh human cadaver eyes . Ophthalmology 1981;88:742-746.Article
8.
Deitz M, Sanders DR, Marks RG:  Radial keratotomy: An overview of the Kansas City study . Ophthalmology 1984;91:467-478.Article
9.
Sanders D, Deitz M, Gallagher D:  Factors affecting predictability of radial keratotomy . Ophthalmology 1985;92:1237-1243.Article
10.
Arrowsmith PN, Marks RG:  Evaluating the predictability of radial keratotomy . Ophthalmology 1985;92:331-338.Article
11.
Waring GO, Moffitt SD, Gelender H, et al:  Rationale for and design of the National Eye Institute prospective evaluation of radial keratotomy (PERK) study . Ophthalmology 1983;90:40-58.Article
12.
Waring GO, Lynn MJ, Gelender H, et al:  Results of the prospective evaluation of radial keratotomy (PERK) study one year after surgery . Ophthalmology 1985;92:177-198.Article
13.
Steinberg EB, Waring GO:  Comparison of two methods of marking the visual axis on the cornea during radial keratotomy . Am J Ophthalmol 1983;96:605-608.
14.
Moses RA:  Intraocular pressure , in Moses RA (ed): Adler's Physiology of the Eye: Clinical Application , ed 7. St Louis, CV Mosby Co, 1981, pp 246-249.
15.
Neter J, Wasserman W, Kutner M: Applied Linear Statistical Models: Regression, Analysis of Variance and Experimental Designs , Homewood, Ill, Richard D Irwin, Inc, 1985.
16.
Arrowsmith PN, Sanders DR, Marks RG:  Visual, refractive, and keratometric results of radial keratotomy . Arch Ophthalmol 1983;101:873-881.Article
17.
Fyodorov SN, Durnev VV:  Operation of dosaged dissection of corneal circular ligament in cases of myopia of mild degree . Ann Ophthalmol 1979;11:1885-1890.
18.
Bores LD, Myers W, Cowden J:  Radial keratotomy: An analysis of the American experience . Ann Ophthalmol 1981;13:941-948.
19.
Hoffer K, Darin J, Pettit T, et al:  Three years' experience with radial keratotomy the UCLA study . Ophthalmology 1983;90:627-636.Article
20.
Neumann AC, Osher RH, Fenzl RE:  Radial keratotomy: A comprehensive evaluation . Ophthalmology 1984;56:275-301.
21.
Rowsey JJ, Balyeat HD, Rabinovitch B, et al:  Predicting the results of radial keratotomy . Ophthalmology 1983;90:642-654.Article
22.
Waring GO:  Review: The changing status of radial keratotomy for myopia: II . J Refract Surg 1985;1:119-137.
23.
Thornton S:  Thornton guide for radial keratotomy incisions and optical zone size . J Refract Surg 1985;1:29-33.
24.
Deitz M:  Careful evaluation of the radial keratotomy patient , in Schachar R, Levy N, Schachar L (eds): Refractive Modulation of the Cornea . Denison, Tex, LAL Publishing, 1981, pp 315-319.
25.
Busin M, Suarez H, Bieber S, et al:  Overcorrected visual acuity improved by antiglaucoma medication after radial keratotomy . Am J Ophthalmol 1986;101:374-375.
26.
Busin M, Yau C, Avni I, et al:  The effect of changes in intraocular pressure on corneal curvature after radial keratotomy in the rabbit eye . Ophthalmology 1986;93:331-334.Article
27.
Gotliar A, Schubert H, Mandel E, et al:  Excimer laser radial keratotomy . Ophthalmology 1985;92:206-208.Article
28.
Brightwell J, Riddle S, Eiferman R, et al:  Biosynthetic human EGF accelerates healing of neodecadron treated primate corneas . Invest Ophthalmol Vis Sci 1985;26:105-110.
×