Chapter-05 Optical Biometry with IOL Master (Partial Coherence Interferometry)

2010 ◽  
pp. 99-106
Author(s):  
Ashok Garg
Keyword(s):  
Partial Coherence ◽  
Optical Biometry ◽  
Partial Coherence Interferometry

scholarly journals Refractive results after cataract surgery using Optical biometry

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Muneer Quraishy ◽  
Mehvish Hussain ◽  
Muhammad Akram
Keyword(s):  
Cataract Surgery ◽  
Intraoperative Complications ◽  
Case Series ◽  
Partial Coherence ◽  
Ophthalmological Examination ◽  
Corneal Incision ◽  
Optical Biometry ◽  
Partial Coherence Interferometry ◽  
Clear Corneal Incision ◽  
Refractive Outcomes

Purpose: To assess the refractive outcome of optical biometry (Nidek AL-scan) after elective phacoemulsification in a study of 30 eyes. Study Design:  Descriptive case series. Place and Duration of Study:  Elective cataract surgeries done at a private clinic from July 2015 to June 2016 were selected and their records were analyzed. Material Methods:  The measurements of IOL calculation was done using optical biometry with partial coherence interferometry (Nidek AL-scan) that provides information about axial length, central keratometry, white to white diameter and anterior chamber anatomical depth. SRK-T formula was used to calculate IOL power. All patients underwent a complete ophthalmological examination. Phacoemulsification with clear corneal incision of 2.75 mm was done and IOL was implanted in the bag (Alcon Acrysof SN60WF IOL and MA60AC IOL). Post-operative refraction was taken with autorefractor (Huvitz HRK-7000) after 4 weeks and it was compared with pre-operative objective refraction. Comparison of K readings taken by AL-scan and autorefractor were done. Results:  We studied 30 eyes of 23 patients who underwent elective cataract surgery with foldable IOL. Post-operative spherical equivalent was plano in 53% of cases with mean of -0.05 after 4 weeks postoperatively. The mean keratometric power using autorefractor was 44.4 D while with AL-scan it was 44.7 D. There were no intraoperative complications or postoperative subjective complaints (such as halo or glare) in our patients. Conclusion:  Intraocular lens power calculations done by optical biometry are easy to use, reliable and result in excellent refractive outcomes.  Ultrasound biometry may still be required in case of mature and dense posterior subcapsular cataract.

scholarly journals Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

2021 ◽  
Author(s):  
Matthias Fuest ◽  
Niklas Plange ◽  
David Kuerten ◽  
Hannah Schellhase ◽  
Babac A. E. Mazinani ◽  
...  
Keyword(s):  
Axial Length ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Partial Coherence ◽  
Power Calculation ◽  
Partial Coherence Interferometry ◽  
Intraocular Lens Power Calculation ◽  
Hyperopic Shift ◽  
Lens Power ◽  
Lens Power Calculation

Abstract Purpose We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL). Methods We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae. Results The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs. Conclusions In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

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