• Users Online: 402
  • Print this page
  • Email this page


 
 Table of Contents  
LETTER TO THE EDITOR
Year : 2021  |  Volume : 59  |  Issue : 1  |  Page : 117-119

The hidden culprit for toric intraocular lens selection - Influence of posterior corneal astigmatism in various astigmatism types


1 Department of Cataract and Refractive Surgery, Mahathma Eye Hospital Private limited, Tiruchirappalli, Tamil Nadu, India
2 Department of Glaucoma and Research, Mahathma Eye Hospital Private limited, Tiruchirappalli, Tamil Nadu, India
3 Department of Paediatric Ophthalmology and Strabismus, Mahathma Eye Hospital Private limited, Tiruchirappalli, Tamil Nadu, India

Date of Submission12-Aug-2020
Date of Acceptance30-Aug-2020
Date of Web Publication27-Mar-2021

Correspondence Address:
Dr. Prasanna Venkatesh Ramesh
Mahathma Eye Hospital Private Limited, No 6, Tennur, Seshapuram, Trichy - 620 017, Tamil Nadu
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/tjosr.tjosr_109_20

Get Permissions


How to cite this article:
Ramesh SV, Ramesh PV, Ramesh MK, Rajasekaran R. The hidden culprit for toric intraocular lens selection - Influence of posterior corneal astigmatism in various astigmatism types. TNOA J Ophthalmic Sci Res 2021;59:117-9

How to cite this URL:
Ramesh SV, Ramesh PV, Ramesh MK, Rajasekaran R. The hidden culprit for toric intraocular lens selection - Influence of posterior corneal astigmatism in various astigmatism types. TNOA J Ophthalmic Sci Res [serial online] 2021 [cited 2021 Apr 22];59:117-9. Available from: https://www.tnoajosr.com/text.asp?2021/59/1/117/312272



Posterior corneal astigmatism has revolutionized the management of astigmatism in cataract patients with toric intraocular lenses (IOLs). Its effect has made a shifting paradigm in toric selection criteria, especially in the era where cataract surgery is considered as a refractive surgery.

We had an experience where a patient visiting for cataract surgery had a keratometric analysis with optical biometry (Lenstar) revealing corneal astigmatism of 0.48 D at 166°, for which considering the small quantity of astigmatism, monofocal, nontoric IOL (AcrySof® IQ) was advised and implanted. However, during the postoperative period, the patient had an unaided visual acuity of 20/40 and, with correction of −1.00 D cylinder at 90°, had a best-corrected visual acuity of 20/20. Considering this postoperative surprise, we did a retrospective analysis. The patient's preoperative data were entered into the online Alcon toric calculator which showed that the patient had required a SN6AT3 model to achieve emmetropia postoperatively [Figure 1]. Such a scenario would be a major setback in cases of multifocal IOL implantation.
Figure 1: Alcon online toric calculator shows that for our patient who had against-the-rule astigmatism required a SN6AT3 model (red arrow) to achieve emmetropia postoperatively, and if a nontoric intraocular lens (red circle) was implanted, the patient would have a postoperative residual astigmatism of 0.88 D at 174°

Click here to view


Posterior corneal astigmatism varies between −0.26 D and −0.78 D.[1] Ideally, articles suggest how it impacts the outcome for toric surgeries, but it plays a major role in selection criteria for toric IOL implantation. The majority of the cataract practitioners choose toric cases only when the magnitude of corneal astigmatic is >0.75 D.[2],[3] Interestingly, against-the-rule astigmatism throws a curveball at us with regards to toric outcome in terms of posterior corneal astigmatism, especially in such low magnitudes. Hence, it is essential to not just take the magnitude of astigmatism but also the type of astigmatism in your inclusion criteria for toric IOLs.

Hence, instead of reserving toric calculation for only a specific set of patients, we would suggest the utilization of online toric calculators for all patients [Figure 2] undergoing microincision cataract surgery and based on its suggestion to go ahead with IOL implantation to avoid such surprises.
Figure 2: Alcon online toric calculator. (a) Hypothetical situation where the same magnitude of astigmatism, if present as with-the-rule astigmatism, then the calculator would suggest a nontoric intraocular lens (red arrow) for the patient to achieve emmetropia. (b) Similarly, if the patient had presented with oblique astigmatism, the calculator would suggest a SN6AT2 model intraocular lens (red arrow) to achieve emmetropia

Click here to view


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Mohammadi SF, Khorrami-Nejad M, Hamidirad M. Posterior corneal astigmatism: A review article. Clin Optom (Auckl) 2019;11:85-96.  Back to cited text no. 1
    
2.
Khan MI, Ch'ng SW, Muhtaseb M. The use of toric intraocular lens to correct astigmatism at the time of cataract surgery. Oman J Ophthalmol 2015;8:38-43.  Back to cited text no. 2
[PUBMED]  [Full text]  
3.
Kaur M, Shaikh F, Falera R, Titiyal JS. Optimizing outcomes with toric intraocular lenses. Indian J Ophthalmol 2017;65:1301-13.  Back to cited text no. 3
[PUBMED]  [Full text]  


    Figures

  [Figure 1], [Figure 2]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
References
Article Figures

 Article Access Statistics
    Viewed132    
    Printed0    
    Emailed0    
    PDF Downloaded13    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]