I would like to comment on the article by Lever and Dahan1 on the use of opposite, penetrating, clear corneal incisions to correct preexisting astigmatism in cataract surgery. These authors address what may arguably be the most important current challenge of modern cataract and implant surgery—the refinement of the refractive outcome. The reduction of preexisting astigmatism can be accomplished in several ways including modification and relocation of the phaco incision, adjunctive use of corneal or intralimbal relaxing incisions, toric intraocular lenses, or the more technologically sophisticated but economically and logistically cumbersome excimer ablative techniques. The authors proffer making clever use of dual, opposite, single-plane penetrating clear corneal incisions placed on the steep meridian.
Their approach, as they point out, offer 2 obvious and significant advantages. Technically, it requires little in the way of new or additional surgical skills. Second, no additional instrumentation is required. Additional incision considerations, however, deserve comment.
Many surgeons, myself included, use single-plane, beveled (paracentesis style) temporal clear corneal incisions as described by I. Howard Fine, MD, for their efficacy and ability to provide astigmatically neutral results.2,3 It is well recognized that a “grooved” or corneal-perpendicular incision, for a given arc length, is more effective at flattening the meridian in which it is placed.4 If one's goal is to flatten a steep meridian, it seems counterintuitive to have to make longer, and in this case penetrating, incisions that are less capable than perpendicular incisions of creating the desired effect.
The authors correctly point out that single-plane incisions of proper tunnel length are quite secure and not likely to leak, particularly the second “unused” incision. Again, intuitively, it seems improper or at least excessive to place additional penetrating incisions if they can be avoided. This becomes particularly important if, as the authors suggest, a nomogram is devised such that penetrating incisions are to be lengthened to correct higher levels of astigmatism. For may of us, a clear corneal penetrating incision of any design that is greater than 4.0 mm in arc length requires suturing to ensure a secure closure.
For these reasons, I prefer to use a consistent temporal single-plane incision (which obviates the need to relocate around the operating table) that is kept at or below 3.5 mm in length and then superimpose on this incision paired intralimbal perpendicular relaxing incisions of variable arc length based on the level of preexisting astigmatism. Similar techniques and nomograms have been described.5–7
Having advocated and taught this technique to many surgeons who had not performed astigmatic keratotomy, I do appreciate the consideration of additional technical skill acquisition as well as the cost of obtaining additional instrumentation, and for this reason congratulate the authors on their novel technique. I strongly feel, however, that the performance of intralimbal relaxing incisions falls well within the purview and skill set of the contemporary phaco surgeon, and ultimately we must choose surgical technique and instrumentation that provide our patients with the best possible results.
Louis D Nichamin MD
aBrookville, Pennsylvania, USA
1. Lever JL, Dahan E. Opposite clear corneal incisions to correct pre-existing astigmatism in cataract surgery. J Cataract Refract Surg 2000; 26:803-805
2. Fine IH. Corneal tunnel incision with a temporal approach. In: Fine IH, Fichman RA, Grabow HB, eds, Clear-Corneal Cataract Surgery and Topical Anesthesia. Thorofare, NJ, Slack, 1993; 5-26
3. Masket S, Tennen DG. Astigmatic stabilization of 3.0 mm temporal clear corneal cataract incision. J Cataract Refract Surg 1996; 22:1451-1455
4. Fine IH. Clear corneal lens surgery. In: Fine IH, Hoffman RS, eds, Controversies Regarding Clear Corneal Incisions. Thorofare, NJ, Slack, 1999; 7-20
5. Budak K, Friedman NJ, Koch DD. Limbal relaxing incisions with cataract surgery. J Cataract Refract Surg 1998; 24:503-508
6. Gills JP. Reducing preexisting astigmatism. In: Gills JP, Fenzl RE, Martin RG, eds, Cataract Surgery: the State-of-the-Art. Thorofare, NJ, Slack, 1998; 53-63
7. Thornton SP. Radial and Astigmatic Keratotomy: the American System. Thorofare, NJ, Slack, 1994