Excimer laser ablation of a corneal protuberance

Excimer laser ablation of a corneal protuberance

Excimer laser ablation of a corneal protuberance R. Brancato, M.D. A. Scialdone, M.D. F. Carones, M.D. A. Bertuzzi, M.D. ABSTRACT The ablation of a p...

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Excimer laser ablation of a corneal protuberance R. Brancato, M.D. A. Scialdone, M.D. F. Carones, M.D. A. Bertuzzi, M.D.

ABSTRACT The ablation of a post-traumatic superficial corneal nodule with an argon fluoride excimer laser is reported. Three months postoperatively the area had a smooth surface with no distortion of adjacent cornea.

Key Words: corneal nodule, excimer laser surgery, phototherapeutic keratectomy

The argon fluoride excimer laser emitting at 193 nm has been used to remove pathological tissue in the anterior corneal stroma. 1 We report the treatment of a post-traumatic superficial corneal nodule using this excimer laser. CASE REPORT A 37-year-old man was referred for surgery of a traumatic cataract in his left eye. Twenty-two years earlier a non-penetrating injury had caused a corneal wound that had not been repaired surgically. On examination the patient's visual acuity in the right eye was 20/20 with plano -1.25 X 95, and in the left was 20/50 with -0.50 -2.00 X 95. Biomicroscopy showed the right eye was normal; in the left eye there was a smooth protuberance of the superficial stroma of about 1.5 X 1 mm at the 3 o'clock corneal meridian, 2.5 mm from the corneal apex. The stroma behind it was transparent (Figure 1). There was no visible disruption of the pos-

Reprint requests to R. Brancato, M.D., Department o/Ophthalmology, University o/Milan, Scientific Institute H. San Raffaele, Via Olgettina, 60, 20132 Milan, Italy.

Fig. l.

(Brancato) Slitlamp photograph of the corneal protuberance. .

terior endothelial layer. A posterior cortical cataract impeded the view of the ocular fundus. With videokeratography, the optical zone appeared unaffected by the nodule. Optical pachymetry showed the tubercle elevation was about 25 J,tm. Since the nodule caused the patient a bothersome foreign body sensation and dry eye, a therapeutic keratectomy was suggested. Ablation was performed using the Summit UV 200 excimer laser with 180 mJ/cm 2 , repetition rate 10 Hz, beam diameter 1.5 mm. Two hundred twenty pulses were delivered. The epithelium was not removed and no fluid was used to coat the surrounding stroma. After treatment, antibiotic drops and a pressure patch were applied until full epithelial regrowth on the third day. Three weeks later some subepithelial and anterior stromal haze was evident. At the latest examination, three months after treatment, the ablated area was barely visible (Figure 2). Videokeratography showed the regular surfaces of the cornea in the temporal quadrant, with no modification of the optical zone. DISCUSSION Laser excision of a fibroplastic corneal nodule at the apex of a keratoconic cornea has been reported by Steinert and Puliafito. 2 In both their report and our case laser ablation produced a good clinical result and appeared to be a reliable technique for the treatment of a definite corneal protuberance. Depth of ablation can be predetermined only approximately because of the ill-defined stromal endpoint of the optical pachymeter and the differ-

J CATARACT REFRACT SURG-VOL 18, JANUARY 1992

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growth. The endpoint for the procedure was, therefore, judged directly by the surgeon. No fluid was used to coat the surrounding cornea except for moistening water that was not dried before laser use. This may have resulted in slightly deeper ablation of the margins of the wound, but no significant difference could be detected by slitlamp examination. A coating fluid may be advisable for higher protrusions. Surgical removal of a small protuberance requires very fine and precise lamellar dissection. While sufficient accuracy may not be easy to achieve manually, excimer laser excision was shown to be a quick and effective procedure. Fig. 2.

(Brancato) The eye three months after excimer laser treatment.

ent ablation rate of the corneal epithelium. Leaving the epithelium in place reduced the total area of tissue damage and the time needed for epithelial

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REFERENCES 1. Stark WJ, Gilbert ML, Goodman GL, et al. Phototherapeutic keratectomy. Preliminary report. ARVO abstracts. Invest Ophthalmol Vis Sci 1990; 31(4):245 2. Steinert RF, Puliafito CA. Excimer laser phototherapeutic keratectomy for a corneal nodule. Refract Corneal Surg 1990; 6:352

J CATARACT REFRACT SURG-VOL 18, JANUARY 1992