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Dr. Md. Rezwanul Hasan
Jr. Consultant
Deep Eye Care Foundation
Biometry is the process of measuring the
power of the cornea ( keratometry) and the
axial length of the eye, by using the data to
determine the ideal intraocular lens (IOL)
power.
Biometry essentially includes:
 Measurement of axial length (AL)
 Keratometry (K- reading), i.e. measurement
of corneal power and
 Effective IOL position
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Average eye 2.50D
Short eye 1.75D
Long eye 3.75D
 Used to measure the corneal curvature
 1D error results 1D error in IOL power
calculation
 Types of keratometer
1. Mannual
2. Auto keratometer, keratometer
incorporated with IOL Master and Lenster
3.Topography- Placido disc based or
elevation based topography
Clinical discussion on Biometry for IOL power calculation
 Depending upon the basis of their derivation
1. THEORETICAL : these are derived
from geometrical optics
2. REGRESSION FORMULAE : Actual
postoperative refractive results of many lens
implantations are used to predict IOL power
Grouped into various GENERATIONS
1st Generation
SRK I, Hoffer
2nd Generation
Binkhorst, SRK II
3rd Generation
Holladay-1, Hoffer-Q, SRK/T
4th Generation
Holladay-2, Haigis
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Clinical discussion on Biometry for IOL power calculation
Coming up next…
 Aphakic eye
 Keratoconus eye
 Inadequate pt. fixation such as nystagmus,
blepharospasm,strabismus etc.
 Post. Staphyloma
 Silicon oil filled eye
 Macular leisions such as RD,Macular oedema,
tumour, vit. hge.
 Dense Cataract
 Corneal refractive surgery such as LASIK, PRK
 Piggyback IOL
 Eye with high myopia
 Paediatric IOL
That’s all for today…
ALLAH HAFIZ..

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Clinical discussion on Biometry for IOL power calculation

  • 1. Dr. Md. Rezwanul Hasan Jr. Consultant Deep Eye Care Foundation
  • 2. Biometry is the process of measuring the power of the cornea ( keratometry) and the axial length of the eye, by using the data to determine the ideal intraocular lens (IOL) power.
  • 3. Biometry essentially includes:  Measurement of axial length (AL)  Keratometry (K- reading), i.e. measurement of corneal power and  Effective IOL position
  • 8. Average eye 2.50D Short eye 1.75D Long eye 3.75D
  • 9.  Used to measure the corneal curvature  1D error results 1D error in IOL power calculation  Types of keratometer 1. Mannual 2. Auto keratometer, keratometer incorporated with IOL Master and Lenster 3.Topography- Placido disc based or elevation based topography
  • 11.  Depending upon the basis of their derivation 1. THEORETICAL : these are derived from geometrical optics 2. REGRESSION FORMULAE : Actual postoperative refractive results of many lens implantations are used to predict IOL power Grouped into various GENERATIONS
  • 12. 1st Generation SRK I, Hoffer 2nd Generation Binkhorst, SRK II 3rd Generation Holladay-1, Hoffer-Q, SRK/T 4th Generation Holladay-2, Haigis
  • 23.  Aphakic eye  Keratoconus eye  Inadequate pt. fixation such as nystagmus, blepharospasm,strabismus etc.  Post. Staphyloma  Silicon oil filled eye  Macular leisions such as RD,Macular oedema, tumour, vit. hge.  Dense Cataract
  • 24.  Corneal refractive surgery such as LASIK, PRK  Piggyback IOL  Eye with high myopia  Paediatric IOL
  • 25. That’s all for today… ALLAH HAFIZ..