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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 1  |  Page : 92-94

Postoperative high astigmatism - Refractive surprise following manual small-incision cataract surgery


Department of Cataract and IOL, Aravind Eye Hospital, Coimbatore, Tamil Nadu, India

Date of Submission28-May-2021
Date of Acceptance28-Aug-2021
Date of Web Publication07-Jan-2022

Correspondence Address:
Dr. A Arut Priya
Department of Cataract and IOL, Aravind Eye Hospital, Civil Aerodrome Post, Sitra, Coimbatore, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_1445_21

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  Abstract 


Postoperative astigmatism plays an important role in the final visual outcome of cataract surgery. In small-incision cataract surgery, proper tunnel construction is of utmost importance for good structural integrity, leading to sutureless self-sealing wounds with lesser astigmatism. We report a case of postoperative high astigmatism following manual small-incision cataract surgery due to large, irregular, superficial, and more anterior corneal entry that lead to poor tunnel valve effect and wound sagging. This resulted in a poor postoperative unaided visual outcome.

Keywords: Astigmatism, corneoscleral tunnel, manual small-incision cataract surgery


How to cite this article:
Balasaraswathy, Priya A A, Narendran K, Sagam N. Postoperative high astigmatism - Refractive surprise following manual small-incision cataract surgery. Indian J Ophthalmol Case Rep 2022;2:92-4

How to cite this URL:
Balasaraswathy, Priya A A, Narendran K, Sagam N. Postoperative high astigmatism - Refractive surprise following manual small-incision cataract surgery. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Jan 23];2:92-4. Available from: https://www.ijoreports.in/text.asp?2022/2/1/92/334879



One of the most common complication after cataract surgery is decreased visual function due to residual astigmatism.[1] In case of manual small incision cataract surgery tunnel construction is an important parameter for self sealing property of the tunnel. Here, in this case report we have discussed about postoperative high astigmatism as a result of improper tunnel construction and challenges faced to minimise the residual high astigmatism.


  Case Report Top


A 77-year-old male patient was diagnosed with immature cataract in the left eye. His preoperative uncorrected visual acuity (UCVA) was 6/36 with −1.00D [email protected] 90° to 6/12. He underwent small-incision cataract surgery in the same eye. The patient was reviewed after 1 week; his UCVA was 5/60 and BCVA was 6/24 with −4.00D [email protected]°. IOL master keratometry showed [email protected]° and Orbscan showed [email protected]° [Figure 1]. On examination of the tunnel, it was large, with irregular inner edges, thin tunnel roof, and corneal entry was made more anterior into clear cornea [Figure 2]. Because of the abovementioned intraoperative factors, tunnel valve integrity was lost and caused wound sagging and led to cylinder up to 9.50D on the plane of incision. The patient was advised wound exploration and tunnel suturing. Intraoperatively, the tunnel was secured with seven interrupted tight sutures. Postoperatively, UCVA improved to 6/18 and BCVA was − [email protected] 6/6. IOL master keratometry showed cyl − [email protected]° and Orbscan showed [email protected]° [Figure 3]. [Table 1] shows a comparison of IOL master values preoperatively, postoperatively, and after resurgery.
Figure 1: Orbscan showing high cylinder and against-the-rule astigmatism in keratometry map

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Figure 2: Slit-lamp photo; black arrow showing more ragged and anterior entry into the cornea

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Figure 3: Orbscan after resurgery, showing reduced cylinder with the rule astigmatism in keratometry map

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Table 1: IOL master comparison

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  Discussion Top


Postoperative residual astigmatism is one of the important causes for decreased visual function postoperatively.[1] Even as low as 1.00D astigmatism causes significant visual complaints; if left uncorrected, it can significantly affect the patient's independence, quality of life, and near vision.[1] Corneal incision plays a vital role in the overcorrection or undercorrection of astigmatism.[2] The size of the incision influences the amount of induced astigmatism, with larger incisions typically causing larger changes in astigmatism.[3],[4] Peripheral corneal incisions of 3.0–3.2 mm in width typically lead to approximately 0.50D change in corneal astigmatism, with larger-width 5.0-mm incisions resulting in up to 1.0D of corneal astigmatism change.[3],[4]

The factors that maintain structural integrity and self-sealing valve effect of the tunnel are square incisional geometry, which means the length of the tunnel, and relatively short external scleral incision with a tunnel that flares to a larger corneal internal incision shape that lends itself to stretching.[5],[6] The scleral tunnel has six aspects, which include length of the tunnel, shape, location, depth, width, and entry into the anterior chamber.[7] Type of incision varies according to the surgeon and preoperative astigmatism, but any type of incision will induce less astigmatism if placed more posterior on the sclera and temporally placed incision.[8] Smaller incisions have a tendency to flatten the meridian if placed along it, and larger incisions steepen the meridian right angle to the center of that incision.[9]

In our case, the following factors caused high cylinder: larger incision, irregular inner corneal entry, thin tunnel roof, and more anterior entry into the cornea. All these factors affected the wound integrity and lead to wound sagging and astigmatism. After wound exploration and suturing, postoperatively Orbscan and keratometry showed reduced astigmatism [Figure 3].

Although many cases of postoperative astigmatism have been reported, to the best of our knowledge, this case report is rare as it insists on corneoscleral tunnel construction and if not constructed properly, it may lead to high cylinder even up to 9D cylinder.

Hence, with regard to incision, broad guidelines that help the cataract surgeon to achieve emmetropia are as follows:

Incision along the steep meridian, Longer incisions produce more steepening on the opposite meridian, shorter incisions have a flattening effect on the same meridian, posterior incisions or frown incisions produce less astigmatism than smile incision, regular internal corneal entry induces less astigmatism than irregular ragged entry, superotemporal incision causes less astigmatism than superior incision, and scleral tunnel incisions minimize suture-induced astigmatism and provides greater wound-healing surface, and hence, it is more stable from the refractive standpoint.


  Conclusion Top


Critical analysis of our case demonstrates the causes for postoperative high astigmatism in a patient following manual small-incision cataract surgery. Taking care of wound construction during surgery may help minimize the risk of such complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due to efforts will be made to conceal their identity.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Wolffsohn JS, Bhogal G, Shah S. Effect of uncorrected astigmatism on vision. J Cataract Refract Surg 2011;37:454-60.  Back to cited text no. 1
    
2.
Read SA, Vincent SJ, Collins MJ. The visual and functional impacts of astigmatism and its clinical management. Ophthalmic Physiol Opt 2014;34:267-94.  Back to cited text no. 2
    
3.
Hayashi K, Hayashi H, Nakao F, Hayashi F. The correlation between incision size and corneal shape changes in sutureless cataract surgery. Ophthalmology 1995;102:550-6.  Back to cited text no. 3
    
4.
Kohnen T, Dick B, Jacobi KW. Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes. J Cataract Refract Surg 1995;21:417-23.  Back to cited text no. 4
    
5.
Gautam AK, Nath R, Kumar D, Saxena S. Early re-establishment of blood aqueous barrier after Phacoemulsification. Indian J Ophthalmol 1998;46:173-4.  Back to cited text no. 5
[PUBMED]  [Full text]  
6.
Pallin SL. Self-sealing incision. In: Agarwal S, Bonnett R, Agarwal A, editors. Phacoemulsification. London: Taylor and Francis; 2004. p. 199-204.  Back to cited text no. 6
    
7.
Haldipurkar SS, Shikari HT, Gokhale V. Wound construction in manual small incision cataract surgery. Indian J Ophthalmol 2009;57:9-13.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Haldipurkar SS, Gokhale VN. Astigmatic considerations in SICS. J International Soc Manual Small Incision Cataract Surgeons 2005;46-8.  Back to cited text no. 8
    
9.
Wishart MS, Wishart PK, Gregor ZJ. Corneal astigmatism following cataract extraction. Br J Ophthalmol 1986;70:825-30.  Back to cited text no. 9
    


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