title: Morning-to-evening change in refraction, corneal curvature, and visual acuity 2 to 4 years after radial keratotomy in the PERK Study.
abstract: The authors previously reported morning-to-evening changes in ophthalmic measurements at 3 months and at 1-year after radial keratotomy in a self-selected group of patients in the Prospective Evaluation of Radial Keratotomy (PERK) study. Fifty-two patients included in the earlier study were examined again between 2 1/2 and 4 years after surgery before 10:00 AM and after 5:30 PM on the same day to determine if the changes persisted beyond 1 year after surgery. Between the morning and evening examinations, 31% of the eyes had an increase in minus spherical equivalent power of the manifest refraction of 0.50 to 1.50 diopters; 12% had a change in cylinder power of 0.50 to 1.00 D; 19% had a decrease in uncorrected visual acuity of two to five Snellen lines; and 29% showed central corneal steepening by 0.50 to 1.00 D. Thus, in some patients, morning-to-evening fluctuation persisted until 2 1/2 to 4 years after radial keratotomy.
authors.affiliation: PERK Coordinating Centers, Emory University, Atlanta, GA.
authors.forename: V R
authors.initials: VR
authors.lastname: Santos
authors.forename: G O
authors.initials: GO
authors.lastname: Waring
authors.forename: M J
authors.initials: MJ
authors.lastname: Lynn
authors.forename: D J
authors.initials: DJ
authors.lastname: Schanzlin
authors.forename: N
authors.initials: N
authors.lastname: Cantillo
authors.forename: M E
authors.initials: ME
authors.lastname: Espinal
authors.forename: J
authors.initials: J
authors.lastname: Garbus
authors.forename: N
authors.initials: N
authors.lastname: Justin
authors.forename: V
authors.initials: V
authors.lastname: Roszka-Duggan
mesh_terms: D002940:Circadian Rhythm; D003315:Cornea / Q000473:pathology*; D005069:Evaluation Studies as Topic; D006801:Humans; D007429:Intraocular Pressure; D007646:Keratotomy, Radial / Q000592:standards; D011184:Postoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular; D013997:Time Factors; D014792:Visual Acuity