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Selective argon laser suturelysis versus needle suturelysis to treat induced corneal astigmatism after cataract surgery

Yip, Chee-Chew MBBS (S'pore), MMed (Ophth), FRCSEd, FCSHKa; Lee, Hung-Ming MBBS (S'pore), MMed (Ophth), FRCSEd, FAMSa; Nah, Gerard MBChB (Aberd), MMed (Ophth), FRCSEda; Yong, Victor MBBS (S'pore), FRCSEd, FRCOphth, FAMSa; Au Eong, Kah-Guan MBBS, MMed(Ophth), FRCSEd, FRCS(Glasg), DRCOphth, FAMS*,a

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Journal of Cataract & Refractive Surgery: April 2002 - Volume 28 - Issue 4 - p 689-691
doi: 10.1016/S0886-3350(01)01030-6
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Abstract

Selective needle suturelysis (NS) in the early period after extracapsular cataract extraction (ECCE) can reduce corneal astigmatism. Although there is a gradual natural decay of postoperative corneal astigmatism with time,1 this procedure more rapidly reduces induced astigmatism and facilitates earlier visual rehabilitation. The suture(s) to be lysed is determined by the axis of the astigmatism.

Lieberman2 and Hoskins and Migliazzo3 describe argon laser suturelysis (LS) to manage failing filtering blebs after trabeculectomy. Lieberman2 also suggests using LS with a 4-mirror Goldmann goniolens for astigmatism after cataract surgery as the technique minimizes bleeding and antibiotic treatment.

We conducted a prospective randomized study to compare the complications of NS and LS after cataract surgery. We also compared the patients' subjective experience during the 2 procedures and assessed whether they preferred 1 technique over the other.

Patients and Methods

This prospective randomized study comprised 30 patients (30 eyes) who had more than 3.00 diopters of with-the-rule astigmatism detected with an autorefractometer, keratometer, or both after uneventful ECCE in the Department of Ophthalmology, Tan Tock Seng Hospital, Singapore. The mean age of the patients was 66.2 years (range 45 to 89 years); 58.6% were men and 41.4%, women.

Patients were randomized to receive NS first followed by LS or LS followed by NS. Thirteen (43.3%) eyes had LS first and 17 (56.7%), NS. The suturelysis was performed in the right eye in 12 patients (40.0%) and in the left in 18 (60.0%).

Two sutures along the steepest meridian in each eye were lysed by the same surgeon a mean of 6.9 weeks postoperatively (range 5 to 9 weeks). One suture was lysed with a 27-gauge needle and the other by argon laser using topical anesthesia of proparacaine 0.5%. Laser suturelysis was performed using a blue-green argon laser and a Hoskins suturelysis lens under high magnification. The laser settings were power, 0.5 W; duration, 0.05 seconds; spot size, 50 μm. The mean number of laser shots was 2.6 (range 1 to 6).

All complications during both procedures were recorded. As a small conjunctival or corneal epithelial puncture wound is not unexpected with the use of a needle during routine suturelysis, conjunctival epithelial defect and corneal abrasion in NS cases were defined as a defect larger than the size of a needle puncture wound. Small needle puncture wounds were not included as complications.

The patients were asked to grade their fear and discomfort/pain during the 2 procedures on a subjective scale of 0 to 10 on which 0 was no fear or discomfort/pain and 10, the worst fear or discomfort/pain they have experienced or could imagine. Patients were also asked to compare the 2 procedures in terms of their fear and discomfort/pain. Finally, they were asked whether they had a preference for either procedure.

Results

The complications of LS were mild conjunctival burn (1/30) and conjunctival epithelial defect (1/30) and of NS, conjunctival epithelial defect (17/30), corneal abrasion, (4/30), and subconjunctival hemorrhage (13/30). There were no cases of suture protrusion, conjunctivitis, or corneal or globe perforation with either method.

Tables 1 to 3 show the patients' subjective grading of the fear and discomfort/pain associated with each procedure. Although slightly more than half the patients (53.3%) said they were not fearful during either procedure, a significant proportion (46.7%) said they were more fearful during NS. No patient had more fear during LS. Half the patients found NS to be more uncomfortable or painful. The subjective scores for fear and discomfort in the NS group were statistically significantly higher than those in the LS group (P = .0010 and P = .0014, respectively). Nineteen patients (63.3%) said they preferred LS, 3 (10.0%) preferred NS, and 8 (26.7%) said they had no preference.

Table 1
Table 1:
Patient fear during suturelysis.
Table 2
Table 2:
Patient discomfort/pain during suturelysis.
Table 3
Table 3:
Subjective fear and discomfort/pain scores.

Discussion

The argon laser is a useful alternative to the needle to lyse sutures in the management of astigmatism after ECCE. Laser suturelysis offers several advantages over needle suturelysis. These include minimal manipulation of the conjunctiva, less direct trauma to the conjunctiva, and no risk of globe perforation. It is less invasive and may be safer than needle suturelysis in uncooperative patients such as those with psychotic illness.

The laser settings were adjusted to produce a small, focused, high-energy spot to lyse the suture. We adapted our technique from that used in suturelysis after trabeculectomy. In our experience, the key to successful laser suturelysis is good visualization of the suture. The Hoskins lens,3 which we used, has several features to aid visualization and suturelysis. First, it acts as a miniretractor for the upper eyelid to prevent blinking. Second, the mechanical contact with the conjunctiva blanches the conjunctival vessels and improves visualization of the sutures. Third, the magnification of the lens enhances the accuracy when targeting the laser on the suture. Fourth, the lens acts as a “heat sink,”3 resulting in minimal collateral thermal damage.

In his first report of the LS technique, Lieberman2 used the Goldmann goniolens. Since then, other devices have been used in LS including the Zeiss 4-mirror gonioscopy lens,4 20-gauge fiber-optic endolaser probe,5 glass micropipette,6 and newer lenses designed specifically for LS.7,8

In our study, patients found LS less frightening and more comfortable than NS. It is therefore not surprising that most (63.3%) preferred LS over NS. Laser suturelysis is also safe, with only minor complications (eg, conjunctival burns, conjunctival epithelial defects) occurring in our patients. We have found the technique to be particularly useful in lysing limbal sutures that are buried or covered by conjunctiva. Using a needle to lyse the suture in such cases may cause subconjunctival hemorrhage and conjunctival or corneal epithelial defects. In addition, the suture ends may not protrude after LS in these cases, which may obviate the need for suture removal. Suturelysis has been associated with vision-threatening complications such as wound dehiscence, iris prolapse, bleb formation, and endophthalmitis.9,10 Therefore, patients should be closely monitored after the procedure.

In conclusion, the argon laser is a safe and effective alternative to the needle for suturelysis in the treatment of corneal astigmatism after ECCE. It is associated with fewer complications than NS and is preferred by patients.

References

1. Talamo JH, Stark WJ, Gottsch JD, et al. Natural history of corneal astigmatism after cataract surgery. J Cataract Refract Surg 1991; 17:313-318
2. Lieberman MF. Suture lysis by laser and goniolens. (letter) Am J Ophthalmol 1983; 95:257-258
3. Hoskins HD Jr, Migliazzo C. Management of failing filtering blebs with the argon laser. Ophthalmic Surg 1984; 15:731-733
4. Savage JA, Simmons RJ. Staged glaucoma filtration surgery with planned early conversion from scleral flap to full-thickness operation using argon laser. Ophthalmic Laser Therapy 1986; 1:201-210
5. Salamon SM. Trabeculectomy flap suture lysis with endolaser probe. Ophthalmic Surg 1987; 18:506-507
6. Tomey KF. A simple device for laser suture lysis after trabeculectomy. (letter) Arch Ophthalmol 1991; 109:14-15
7. Ritch R, Potash SD, Lieberman JM. A new lens for argon laser suture lysis. Ophthalmic Surg 1994; 25:126-127
8. Mandelkorn RM, Crossman JL, Olander RW, Heacock G. A new argon laser suture lysis lens. (letter) Ophthalmic Surg 1994; 25:480-481
9. Driebe WT Jr, Mandelbaum S, Forster RK, et al. Pseudophakic endophthalmitis; diagnosis and management. Ophthalmology 1986; 93:442-447; discussion by DM O'Day, 447-448
10. Gelender H. Bacterial endophthalmitis following cutting sutures after cataract surgery. Am J Ophthalmol 1982; 94:528-533
© 2002 by Lippincott Williams & Wilkins, Inc.