Eye Doctor Arizona
Eye Surgery Arizona

  IOL Power Calculations
Post Myopic LASIK
printable version
 
IOL Power Calculations IOL Power Calculations
Post Keratorefractive Surgery Cataract Surgery Arizona
Myopic LASIK
Clinical History Method
Contact Lens Method
Corneal Bypass Method
Feiz-Mannis Method
Haigis-L Formula - Myopic
Latkany Method
Masket Method
Modified Masket Method
Topographic Central Power
Wang Koch Maloney Method
Hyperopic LASIK Cataract Surgery Arizona
Radial Keratotomy
RK + Hyperopic LASIK
"Double K" Formula Corrections
Hoffer Q Formula
Holladay 1 Formula
SRK/T Formula
Post Keratorefractive Calculator
Optical Biometry Optical Biometry
Disclaimer
Physician Downloads SIA Calculator
Links
References
Special Thanks

Clinical History Method.1,2

The Clinical History Method for corneal power estimation was first described by Holladay and later by Hoffer as:

Kp + Rp - Ra = Ka Cataract Surgery ArizonaWhere...

Kp = the average keratometry power before keratorefractive surgery, and...

Rp = the spherical equivalent before keratorefractive surgery, and...

Ra = the stable spherical equivalent after keratorefractive surgery, then...

Ka = the estimate of the central corneal power after keratorefractive Cataract Surgery Arizonasurgery.

Central corneal power by keratometry will be referred to in diopters (D), even though it is better termed keratometric diopters. This is due to the fact that the cornea has a different index of refraction than keratometers, or corneal topographers (1.3333 vs. 1.3375)7

Corrected for an estimated vertex distance of 12 mm, the historical estimation of the central corneal power of the right eye following LASIK would be carried out as follows:

 

If the Ks before LASIK were 45.37 D / 46.00 D, and...

The refraction before LASIK was -6.00 +0.75 x 135, and...

The stable refraction after LASIK was -0.25 sphere, then...

  Kp   +   Rp   -   Ra   =   Ka
               
  (45.69)   +   (-5.27)   -   (-0.25)   =   40.67 D

Corrected for an estimated vertex distance of 12 mm, the historical estimation of the central corneal power of the left eye following LASIK would be carried out as follows:

 

If the Ks before LASIK were 45.25 D / 46.12 D,

The refraction before LASIK was -5.50 +0.75 x 060, and...

The stable refraction after LASIK was -1.25 +0.25 x 070, then...

  Kp   +   Rp   -   Ra   =   Ka
               
  (45.69)   +   (-4.83)   -   (-1.11)   =   41.97 D

If you are unfamiliar with how to correct for vertex distance, follow this link to an Excel spreadsheet for Correcting for Vertex Distance. Be sure to maintain the correct sign (+ or -) when entering the refractive data, or the results will not be accurate.

References

1. Holladay JT. Consultations in refractive surgery. Refract Corneal Surg 1989; 5:203

2. Hoffer KJ. Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg 1995; 11:490-493

 


IOLMaster Help
TOP

IOL Power Calculations After Myopic LASIK

IOL Power Calculations After Keratorefractive Surgery

Intraocular Lens Power Calculations


East Valley Ophthalmology
5620 East Broadway Road
Mesa, Arizona 85206

Tel: +1-480-981-6111
FAX: +1-480-985-2426

Arizona's Top Eye Doctors - East Valley Ophthalmology provides this online information for educational and communication purposes only and it should not be construed as personal medical advice. Information published on this website is not intended to replace, supplant, or augment a consultation with an eye care professional regarding the viewer/user's own medical care. East Valley Ophthalmology's disclaims any and all liability for injury or other damages that could result from use of the information obtained from this site. Please read our full Terms, Privacy, Infringement

Eye Doctors for Mesa, Gilbert, Chandler, AZ and surrounding areas.

A few of our featured topics:


TOP

Copyright East Valley Ophthalmology. All rights reserved.