title: Optics of conductive keratoplasty: implications for presbyopia management.
abstract: OBJECTIVE
  To define the corneal optics of conductive keratoplasty (CK) and assess the clinical implications for hyperopia and presbyopia management.
  
  
  METHODS
  Four analyses were done. (1) Multifocal effects: In a prospective study of CK, uncorrected visual acuity (UCVA) for a given refractive error in 72 postoperative eyes was compared to control eyes. (2) Surgically induced astigmatism (SIA): 203 eyes were analyzed for magnitude and axis of SIA. (3) Higher-order optical aberrations: Corneal higher-order optical aberrations were assessed for 36 eyes after CK and a similar patient population after hyperopic laser in situ keratomileusis (LASIK). (4) Presbyopia clinical trial: Visual acuity, refractive result, and patient questionnaires were analyzed for 150 subjects in a prospective, multicenter clinical trial of presbyopia management with CK.
  
  
  RESULTS
  (1) 63% and 82% of eyes after CK had better UCVA at distance and near, respectively, than controls. (2) The mean SIA was 0.23 diopter (D) steepening at 175 degrees (P < .001); mean magnitude was 0.66 D (SD, 0.43 D). (3) After CK, composite fourth- and sixth-order spherical aberration increased; change in (Z12) spherical aberration alone was not statistically significant. When compared to hyperopic LASIK, there was a statistically significant increase in composite fourth- and sixth-order spherical aberration (P < .01) and spherical aberration (Z12) alone (P < .02); spherical aberration change was more prolate after CK. (4) After the CK monovision procedure, 80% of patients had J3 or better binocular UCVA at near; 84% of patients were satisfied. Satisfaction was associated with near UCVA of J3 or better in the monovision eye (P = .001) and subjectively good postoperative depth perception (P = .038).
  
  
  CONCLUSIONS
  CK seems to produce functional corneal multifocality with definable introduction of SIA and higher-order optical aberrations, and development of a more prolate corneal contour. These optical factors may militate toward improved near vision function.
authors.affiliation: Department of Ophthalmology and Visual Sciences, UMDNJ-New Jersey Medical School, Newark, New Jersey, USA.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hersh
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000209:etiology; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D019781:Corneal Topography; D004867:Equipment Design; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000601:surgery; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000295:instrumentation; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D013508:Ophthalmologic Surgical Procedures / Q000009:adverse effects / Q000295:instrumentation; D011305:Presbyopia / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D011846:Radio Waves / Q000009:adverse effects; D000078702:Radiofrequency Therapy; D013523:Surgical Equipment; D013525:Surgical Instruments; D014792:Visual Acuity