How is IOL calculated?
The assumed index of refraction of the normal cornea is based on the relationship between the anterior and posterior corneal curvatures. This relationship is changed in LASIK eyes. Most IOL power formulas use the axial length and keratometric reading (K) to predict the position of the IOL postoperatively (ELP).
Which is the best formula for IOL calculation?
An analysis of the studies published in the past 50 years reveals that the Haigis, Hoffer Q, and Holladay 2 formulas are the best options for intraocular lens power prediction in short eyes (<22 mm).
What is K reading?
Keratometry (K) is the measurement of the corneal curvature; corneal curvature determines the power of the cornea. The IOL Master also measures the axial length and other ocular parameters (such as anterior chamber depth and white-to-white measurements) and includes K readings.
What is K1 and K2 in keratometry?
Keratometry was measured in 2 meridians: that is, flat keratometry (K1) and steep keratometry (K2). The K value was calculated as the mean of K1 and K2.
What is my axial length?
Axial length (AL) is the primary determinant of non-syndromic myopia. It is a parameter representing the combination of anterior chamber depth, lens thickness and vitreous chamber depth of the eye.
How to calculate the IOL power of the eye?
In conclusion, calculation of the IOL power can be performed using a great variety of formulas. According to clinical studies, the SRK-T formula is recommended for rather long eyes whereas the Hoffer Q formula is recommended for rather short eyes.
What is the most commonly used formula for IOLs?
The most frequently used formulas are based on two measurements, AL and K, as well as a single IOL constant 8 (Holladay 1 ,9 SRK/T 10 and Hoffer Q 11 ).
What is the post-refractive IOL calculator?
Post-Refractive IOL Calculator This calculator facilitates IOL power calculation in eyes that have undergone LASIK/PRK/RK. The IOL Calculator is meant to serve as an adjunct tool to assist physicians in selecting the appropriate IOL for a particular patient.
What is the Haigis formula for IOL?
The Haigis formula recommends an IOL power based on a three-variable (a 0, a 1 and a 2) function. The a 1 constant is tied to the measured ACD, while the a 2 constant is tied to the measured AL. This allows all three constants to be optimized for a wide range of ALs and ACDs using double-regression analysis. These are AL and ACD.