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Year : 2009  |  Volume : 57  |  Issue : 6  |  Page : 477-478

Minimally invasive Knapp's procedure: Modified fornix incision approach

Pediatric Ophthalmology and Strabismus Clinic, Dr. Thakorbhai V Patel Eye Institute, Vadodara, India

Date of Web Publication21-Oct-2009

Correspondence Address:
Jitendra Jethani
Pediatric Ophthalmology and Strabismus Clinic, Dr. Thakorbhai V Patel Eye Institute, Haribhakti Complex, Salatwada, Vadodara- 01
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0301-4738.57148

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How to cite this article:
Jethani J. Minimally invasive Knapp's procedure: Modified fornix incision approach. Indian J Ophthalmol 2009;57:477-8

How to cite this URL:
Jethani J. Minimally invasive Knapp's procedure: Modified fornix incision approach. Indian J Ophthalmol [serial online] 2009 [cited 2023 Dec 1];57:477-8. Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?2009/57/6/477/57148

Dear Editor,

Minimally invasive surgical procedures reduce tissue trauma, postoperative patient discomfort, hospital stay, working disability, and the economic impact of surgery. [1],[2] The majority of surgeons use the limbal approach incision in squint surgery, first described by Harms [3] in 1949 and later popularized by von Noorden. [4] A lot of incisions have been described for simple recession and resection of muscles. Small and micro incisions have been advocated in strabismus surgery too. [5],[6] Traditional incision for Knapp's procedure is a large limbal U-shaped incision [5] similar to the limbal incision but slightly larger. [1],[2] We describe Knapp's procedure via fornix incisions to make it a minimally invasive conjunctival approach. The incisions may be left unsutured too since they would be in the cul de sac.

The patient was prepared for the surgery under general anesthesia. After putting the speculum in place, a 6-0 vicryl stay suture was passed at 10.30 o' clock in right eye and the eyeball was pulled at an angle. Around 8 mm from the limbus in the superotemporal quadrant a conjunctival incision concentric to the limbus was placed [Figure 1]. The conjunctiva and Tenon's was separated and the lateral rectus muscle was hooked. The muscle was freed from its attachments with the conjunctiva, intermuscular ligament and 6-0 vicryl sutures were passed at the insertion. The muscle was cut at the insertion and resutured back near the superior rectus concentric to the limbus. A similar incision was put in the superonasal quadrant and the medial rectus was hooked, sutured, separated and reinserted parallel to the superior rectus on the nasal side concentric to the limbus [Figure 1],[Figure 2],[Figure 3]. At the end of the surgery only two incisions in the upper fornix were seen [Figure 1],[Figure 2] which can be sutured with a single 8-0 vicryl suture or may be left unsutured. The postoperative period showed small, localized areas of redness in the upper nasal and temporal quadrants [Figure 4].

A large range of incisions, limbal, cul de sac and more recently minimally invasive incisions have been described in strabismus surgery. [5],[6] Minimally invasive strabismus surgery (MISS) is becoming popular. The purpose of these smaller and smaller incisions is to reduce the hyperemia, for better healing and earlier patient rehabilitation. [6]

In a study of comparison of limbal incision with the minimally invasive incision, Mojon et al., [6] found that the MISS technique was better than the limbal approach as the former had less dissection, less chances of limbal ischemia and therefore less postoperative tissue scar. However, with a fornix incision all the merits of MISS are available as pointed out by Kushner. [7] We, therefore used the fornix incision for the classic Knapp's procedure and called it minimally invasive Knapp's procedure. Such a possibility has also been hinted at by Coats et al., who have told about both the larger incision and small buttonhole incisions for transposition surgeries. [8] Such incisions, by leaving the limbal conjunctiva undisturbed, may play a role in reducing the risk of anterior segment ischemia. [9] Since a MISS incision could be possibly used for such large displacement of muscles, fornix incision would be a great alternative to the large limbal incision.

The incision for Knapp's procedure is usually a large U-shaped incision starting from the inferior temporal quadrant to the inferonasal quadrant at the limbus (from 8 o' clock to 4 o' clock) (that is around 270 0 ). Such a large incision would cause a lot of dissection and a lot of scar tissue formation postoperatively as a result of the healing process. Also, the conjunctiva superiorly may lead to peripheral opacification of superior cornea. [5]

The cul de sac incision helps in minimizing the bleeding, reduces the unnecessary dissection and may help in earlier healing and therefore earlier rehabilitation of the patient postoperatively. One of the limitations is that the amount of exposure may be slightly reduced. However, we feel that a trained surgeon using a cul de sac incision routinely would find it very easy to put two such separate incisions. Such openings may not allow performing full rectus muscle transposition in older patients with inelastic conjunctiva.

Two small cul de sac incisions can be used to perform a Knapp's procedure. This approach may help in earlier patient rehabilitation and reduced scar formation in patients undergoing Knapp's procedure; however, this needs further research and clinical trials.

  Acknowledgment Top

The author acknowledges Dr. Saumya Chaudhary for her help and valuable suggestions.

  References Top

Darzi A, Mackay S. Recent advances in minimal access surgery. BMJ 2002;324:31-4.  Back to cited text no. 1
Harrell AG, Heniford BT. Minimally invasive abdominal surgery: Lux et veritas past, present, and future. Am J Surg 2005;190:239-43.  Back to cited text no. 2
Harms H. Über Muskelvorlagerung. Klin Monatsbl Augenheilk 1949;115:319-24.   Back to cited text no. 3
von Noorden GK. The limbal approach to surgery of the rectus muscles. Arch Ophthalmol 1968;80:94-7.  Back to cited text no. 4
Helveston EM. In: Surgical management of strabismus. 5th ed. Belgium: Wayenborgh Publications; Chapter 13. p. 272  Back to cited text no. 5
Mojon DS. Comparison of a new, minimally invasive strabismus surgery technique with the usual limbal approach for rectus muscle recession and placation. Br J Ophthalmol 2007;91:76-82.  Back to cited text no. 6
Kushner BJ. Comparison of a new, minimally invasive strabismus surgery technique with the usual limbal approach for rectus muscle recession and plication. Br J Ophthalmol 2007;91:5.  Back to cited text no. 7
Coats DA, Olitsky SE. In: Strabismus surgery and its complications. Springer Verlag, 2007. Chapter 13 p. 135-40.  Back to cited text no. 8
Fishman PH, Repka MX, Green WR, D'Anna SA, Guyton DL. A primate model of anterior segment ischemia after strabismus surgery: The role of the conjunctival circulation. Ophthalmology 1990;97:456-61.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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