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   Table of Contents      
LETTER TO THE EDITOR
Year : 2019  |  Volume : 67  |  Issue : 11  |  Page : 1905-1906

Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia


Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India

Date of Web Publication22-Oct-2019

Correspondence Address:
Dr. Ankur K Shrivastava
603/Type 5A, All India Institute of Medical Sciences, Residential Complex, Kabir Nagar, Raipur - 492 099, Chhattisgarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_780_19

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How to cite this article:
Shrivastava AK, Behera P. Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia. Indian J Ophthalmol 2019;67:1905-6

How to cite this URL:
Shrivastava AK, Behera P. Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia. Indian J Ophthalmol [serial online] 2019 [cited 2019 Nov 18];67:1905-6. Available from: http://www.ijo.in/text.asp?2019/67/11/1905/269639



It was interesting to read the article “Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia” by Zhou et al.[1] The authors have compared the predictive accuracy of five formulas and concluded that Barrett Universal II is the more reliable formula.

However, we wish to point out certain concerns which we thought were important:-

  1. The type of intraocular lens used in the study is not mentioned specifically. Different IOL designs might affect the outcome precision[2],[3]
  2. Mean absolute error (MAE) among the formulas is compared. It is important to note that absolute errors are not a normal Gaussian distribution. Therefore, it is best to compare median absolute error (MedAE) rather than MAE.[4] In results MedAE is mentioned as a heading but under that MAE and interquartile range are described
  3. The differences in mean numerical error and MAE of five formulas were compared but the results were not statistically proven (no P values mentioned)
  4. In Figure 1 and Figure 2 of main article, X-axis should be mentioned as within ± 0.25 D, ± 0.50 D, ± 1.00 D and ± 2.00 D as depicted in [Figure 1].
  5. Figure 3 of the article, depicts as if all patients in groups 1, 2, and 3 have exactly the same axial length, this may not be in reality. Also, it is not fare enough to depict correlation of all three groups in the same figure
  6. Which Holladay formula was used? – Holladay 1 or 2
  7. There is confusion regarding type of biometer used in the study. In methodology Lenstar and contact-type A ultrasound are mentioned while in results IOL master. These three instruments use different technology for biometry. Contact ultrasound biometry is not optimal because of potential corneal compression and shorter axial length and anterior chamber depth measurement.[5]
Figure 1: Percentage of eyes with refractive prediction errors within ± 0.25 D, ± 0.50 D, ± 1.00 D and ± 2.00 D

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Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zhou D, Sun Z, Deng G. Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia. Indian J Ophthalmol 2019;67:484-9  Back to cited text no. 1
    
2.
Maclaren RE, Natkunarajah M, Riaz Y, Bourne RR, Restori M, Allan BD. Biometry and formula accuracy with intraocular lenses used for cataract surgery in extreme hyperopia. Am J Ophthalmol 2007;143:920-31.  Back to cited text no. 2
    
3.
Rhiu S, Lee ES, Kim TI, Lee HS, Kim CY. Power prediction for one-piece and three-piece intraocular lens implantation after cataract surgery in patients with chronic angle-closure glaucoma: A prospective, randomized clinical trial. Acta Ophthalmol 2012;90:e580-5.  Back to cited text no. 3
    
4.
Hoffer KJ, Aramberri J, Haigis W, Olsen T, Savini G, Shammas HJ, et al. Protocols for studies of intraocular lens formula accuracy. Am J Ophthalmol 2015;160:403-5.  Back to cited text no. 4
    
5.
Shammas HJ. A comparison of immersion and contact techniques for axial length measurement. J Cataract Refract Surg 1984;10:444-7. [Figure 1]: Percentage of eyes with refractive prediction errors within ± 0.25 D, ± 0.50 D, ± 1.00 D and ± 2.00 D  Back to cited text no. 5
    


    Figures

  [Figure 1]



 

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