September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Corneal curvature is a key determinant of Haigis and SRKT formulae accuracy of for intentional myopic overcorrection
Author Affiliations & Notes
  • Andre Messias
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Rodrigo Faeda Dalto
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Ferreira Miriam
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Wilian Queiroz
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Roberto Pinto Coelho
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Jayter Silva Paula
    Ophthalmology, University of Sao Paulo, Ribeirao Preto, SP, Brazil
  • Footnotes
    Commercial Relationships   Andre Messias, None; Rodrigo Dalto, None; Ferreira Miriam, None; Wilian Queiroz, None; Roberto Coelho, None; Jayter Paula, None
  • Footnotes
    Support  FAPESP
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 3103. doi:
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      Andre Messias, Rodrigo Faeda Dalto, Ferreira Miriam, Wilian Queiroz, Roberto Pinto Coelho, Jayter Silva Paula; Corneal curvature is a key determinant of Haigis and SRKT formulae accuracy of for intentional myopic overcorrection. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3103.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To compare the influence of the biometric parameters on the accuracy of Haigis and SRKT formulae predicting postoperative target refraction (TR).

Methods : Retrospective analysis of 108 eyes (70 patients) that had uneventful phacoemulsification surgery with implant of Alcon-SN60WF intraocular lens (IOL). In 45 eyes, IOLs were intentionally targeted to myopia (-0.75 to -1.25 dpt), while the other 63 eyes targeted between 0 and -0.75 dpt. Preoperative axial length (AL) and keratometry (K) were measured with optical biometry (LENSTAR – Haag-Streit). Postoperative spherical equivalent (PSE) was assessed 12 ± 3 months after surgery.

Results : Overall, mean PSE - TR showed a small myopic shift of 0.16 ± 0.04 dpt (p<0.05) for Haigis; and -0.02 ± 0.04 dpt (p>0.05) for SRKT formula. The differences between PTR and PSE were significantly correlated with PSE for Haigis (r=-0.65; P<0.01) and SRKT (r=-0.66; P<0.01). There was also a significant difference between Haigis and SRKT predictions: -0.18 ± 0.03 dpt (P<0.001), and the difference between the two formulae is highly dependent on K (r=-0.75; P<0.01). Splitting the data according to preoperative K median, eyes with K < 43.75 targeted at myopia (n=23) showed a significant myopic shift of -0.26 ± 0.09 dpt (P<0.05) with Haigis, but a hyperopic shift of 0.24 ± 0.09 dpt (P<0.05) with SRKT.

Conclusions : Divergences between Haigis and SRKT formulae cause uncertainty choosing the IOL. These data indicate that, in eyes with lower preoperative K, an IOL targeted at myopia might result in a small, but significant myopic shift for Haigis formula, while with SRKT a hyperopic shift can be expected.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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