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   Table of Contents      
ORIGINAL ARTICLE
Year : 1993  |  Volume : 41  |  Issue : 1  |  Page : 17-19

Recurrent pterygia--laser therapy : A preliminary report


Free University of Berlin, Germany

Correspondence Address:
Shabbir Saifuddin
P.O. Box 2896, Dubai, U.A.E

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Source of Support: None, Conflict of Interest: None


PMID: 8225516

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  Abstract 

We report our experience with the use of Argon laser photocoagulation for the treatment of recurrent pterygia. In this study, 36 patients and 42 eyes with recurrent pterygia having undergone previous surgery one or more times, were subjected to laser therapy. The patients were followed up for a period of 9-12 months. The success rate was 92.8% when laser therapy was employed in recurrent pterygia which were excised once, while it was 64.2% in cases where excisions were done two or more times. Argon laser treatment is a safe and effective method of therapy for recurrent pterygia.


How to cite this article:
Saifuddin S, Baum KL. Recurrent pterygia--laser therapy : A preliminary report. Indian J Ophthalmol 1993;41:17-9

How to cite this URL:
Saifuddin S, Baum KL. Recurrent pterygia--laser therapy : A preliminary report. Indian J Ophthalmol [serial online] 1993 [cited 2020 Mar 28];41:17-9. Available from: http://www.ijo.in/text.asp?1993/41/1/17/25631



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Different procedures have been used for the treatment of pterygia and to minimise their recurrence. Several techniques have made it rather difficult to adopt any one of them particularly in recurrent cases.

The recurrence rate of pterygia varies according to the procedures adopted. According to Pinkerton [1], post-operative beta irradiation is very effective in preventing recurrence. However, a recent report with long term follow-up involving a large number of patients undergoing beta irradiation post­operatively shows many complications and a recurrent rate of 12%. The use of argon laser photocoagulation for the treatment of recurrent pterygium was first performed by Caldwell [3] who reported having done 187 photocoagulations to the surgically excised pterygia bed for over nine years and had claimed that this method was most effective in preventing recurrence.

The aim of this work is to show that the laser surgery is an effective method in treating recurrent cases especially in those that were excised once.


  Materials and methods Top


The study included 36 patients with 42 eyes having developed recurrent pterygium after having been previously operated once, twice or more times. Age varied between 37 - 62 years. The cases were classified into:

Group I : 28 eyes had recurrent pterygia after one excision.

Group II : 14 eyes had recurrent pterygia after more than one prior excision.

All cases had undergone simple excision of the pterygium with superficial lamellar keratectomy. Post operatively good corneal surface was obtained so that the chances of dellen formation did not occur. Argon laser was applied on Group I patients who reported recurrence within three months of first excision and Group II patients were those who reported recurrence six months from the first excision, and within this period had undergone a second or third excision.

A routine ophthalmic examination was conducted after which a few drops of local anaesthetic agent were instilled in the eyes. The patient was positioned on the slit-lamp of the laser unit and a wire speculum was inserted. The laser controls were set to a spot size of 50 microns, a time exposure of 0.1 - 0.2 seconds and a power of 0.2 - 0.3 watts, and the number of shots were 300 - 550 per sitting, according to the individual cases. The shots were arranged in 4 rows parallel to the limbus (diagram) with about 1.5 mm distance between each row. The first row lies just on the scleral side of the limbus. In this manner all the vessels within the 4 rows were occluded. The neovascular fronds near the limbus were also treated with overlapping laser burns, thus destroying the neovascular tissue to minimise recurrence.

The ideal laser applications were those which simply closed off the conjunctival vessels and also those on the bare area but did not produce conjunctival burn. This was achieved by keeping the laser parameters as mentioned. For any larger vessels, a total of 4 - 5 applications were needed to stop the flow into them. The vessels in the bed were assumed closed when the epithelium was totally healed and eye quiet. This took nearly 4 -5 weeks in Group I and slightly longer in Group II cases.

In few cases, the wattage had to be increased to 0.5 to close the superficial vessels.

Immediate post-operative treatment was as follows:

1) Antibiotic-Steriod drops every second hourly/day for first 2 days and then sixth hourly/day upto 7 days.

2) Antibiotic-Steriod ointment (hs) for 3 days.

3) Artificial tears applied second hourly for first 3 - 4 days to keep the corneal surface moist.

The patients were seen on second post-operative day and thereafter follow-up appointment was scheduled for the second or third week after the therapy, and then once every month for a period of 9 - 12 months.


  Results Top


In Group I, 26 eyes were considered successful, thus giving a success rate of 92.8%. The eyes were clear white with quiet pterygium bed from the second post-operative day upto nearly twelve months of follow-up. Two eyes showed neovascularisation growing into the cornea.

In Group II, 9 out of 14 eyes were considered successful, while the remaining cases showed active neovascular tufts mainly in the perilimbal area. Thus the success rate was 64.2%. Another laser therapy was mandatory at the sixth - seventh post-operative week to eradicate neovascularization.

But during the twelve months of follow-up these cases again developed new vessels within six weeks and they were considered as unfavourable cases. Since topical anaesthetic drops were used the patients did not complain of any ocular discomfort.


  Discussion Top


Inspite of numerous techniques and improvements in microsurgery, recurrence of pterygium is still a major concern for the ophthalmic surgeons.

The etiopathology of why pterygium occurs and recurrs is explained by Paton [4]. He postulated that the exposure to dryness, hot weather and ultraviolet rays cause the primary thickening of a limbal mass leading to limbal elevation. This in turn causes irritation and further elevation which in turn causes exposure of the cornea due to improper apposition of the lids. Thus a dellen forms and prevents a smooth tear film from covering the cornea. Caldwell 3 explained that the exposure and dryness produce anoxic condition of the cornea.

Clinically, the recurring pterygium with neovascular tufts shows that it is actively growing, and these neovascular tufts explain why pterygium recurrs. If the neovascualrization can be prevented from growing into healing cornea and the pterygium bed, then the recurrence can be stopped. This is what is achieved with laser treatment. Argon laser emits a coherent blue-green light of about 488-515 nm wavelength. Conversion of laser light into heat energy produces the therapeutic thermoablative effect. As the laser is applied under slit-lamp magnification, it provides a selective and accurately controlled ablation to the pterygium bed without affecting the surrounding healthy tissues.

This study demonstrates the successful use of argon laser therapy to treat recurrent pterygium. Our results are almost similar to that of Caldwell [3]. In Group I, the success rate is almost 93% and in Group II, the success rate is about 64%. Other procedures such as beta irradiation may fail to yield higher success rate, and may also be accompanied by unacceptable long term complications like scleral necrosis, scleromalacia, secondary iritis and cataract [1],[2],[5],[6],[7]. A long term study has challenged the generally accepted wisdom that beta irradiation therapy is both safe and effective, the recurrence rate reported is 12% [2].

Apart from high success rate, the laser therapy is less time consuming and is well tolerated by the patients. However, the procedure has some limitations. It cannot be applied to patients with head tremors and those who are bedridden. It is also difficult to the very nervous and young cases who do not cooperate enough to facilitate the precise application of laser.

Our assumption why the recurrence in Group II occurs is because in these cases due to repeated operations, the surgical insult acts as a stimulus for neovascularization and thus recurrence takes place.

Our results confirm that laser therapy is a safe and effective substitute for other modalaties in post-operative care of the excised pterygium.

 
  References Top

1.
Pinkerton OD. Surgical and Strontium treatment of pterygium, recurrence and lens changes. Ophth Surgery 10 (9): 45-47, 1979.  Back to cited text no. 1
    
2.
MacKenzie FD, Hirst LW, Dynaston B and Bain C. Recurrence rate and complications after beta irradiation for pterygia. Ophthalmology 98:1776-1781, 1991.  Back to cited text no. 2
    
3.
Caldwell DR. Laser surgery for primary and recurrent pterygia. Highlights of Ophthalmology. 30th anniversary edition. Vol. 1: 534-545, 1985.  Back to cited text no. 3
    
4.
Paton D. Pterygium management based upon a theory of pathogenesis. Trans Amer Acad Ophthalmol & Otolaryng. 79: 603-612, 1975.  Back to cited text no. 4
    
5.
Cameron MC : Preventable complications of pterygium excision with beta radiation. Br J Ophthalmol. 56: 52-56, 1972.  Back to cited text no. 5
    
6.
TarrKH and Constable IJ. Late complications of pterygium treatment. Br J Ophthalmol. 64: 496-505,1980.  Back to cited text no. 6
    
7.
Merriam GR. Late effects of beta radiation on the eye. Arch Ophthalmol. 53: 708-717, 1955.  Back to cited text no. 7
    


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