Simultaneous pterygium and cataract surgery.A Gulani, YK Dastur
Dept of Ophthalmology, KEM Hospital, Parel, Bombay.,
In our country both pterygium and cataract have a high incidence. Hence in this study, thirty patients with pterygium and cataract were treated with a simultaneous pterygium excision and cataract extraction procedure. These patients after pterygium excision were treated intra-operatively with 500 rads of beta radiation over the pterygium site. Then, the cataract was extracted and the patients were treated post-operatively with topical betamethasone 0.1% for a duration of three months. They were followed up for a duration of 6 months postoperatively. Nineteen patients (63%) had visual recovery to 6/12. Twelve of 30 patients (40%) had recurrence of pterygium. The combined procedure did not result in any surgical complications following cataract removal. Post-operatively, after 6 months 13 patients had with the rule astigmatism (WRA) for a mean WRA of 1.3 D, and 17 had against the rule astigmatism (ARA) for a mean ARA of 1.2 D.
Keywords: Adult, Aged, Aged, 80 and over, Cataract, complications,Cataract Extraction, Female, Human, Male, Middle Age, Prospective Studies, Pterygium, complications,surgery,Treatment Outcome,
Pterygium is a wing shaped layer of vascularised fibroelastic tissue that arises from the limbic conjunctiva and extends over the cornea and replaces Bowman's membrane and corneal epithelium. Loss of vision occurs if it extends across the visual axis. Pterygium is a common disease in tropical countries. Senile cataracts occur at an earlier age and have a higher incidence in the Indian subcontinent. Hence this study is conducted with the aim of evaluating a combined procedure consisting of pterygium excision and cataract extraction. Beta radiation has been used intra-operatively and topical betamethasone 0.1 % post-operatively, in order to reduce the pterygium recurrence rate,,,,. Both beta radiation and topical betamethasone have a tendency to delay wound heating and their effect on healing of the cataract incision is evaluated. Further, the effect of the combined procedure on the postoperative astigmatism has been studied by doing retinoscopy and by estimation of the visual recovery.
Thirty patients (age range.. 33-82 years; MY = 23:7) having both pterygium and senile cataract (n = 30 eyes) and able to attend a 6 months follow-up regularly were selected for this prospective study. Those with multiple pterygia, recurrent pterygium, traumatic cataract, complicated cataract and cataract with posterior segment disorders were not included in this study. Demographic data of these patients is shown in [Table - 1]. Fourteen of 30 patients (47%) were in the age group of 45-60 years. Sex distribution showed that 23/30 cases (77%) were males.
Seven eyes of 30 patients had atrophic non-progressive pterygium of size less than 3 mm while in 23 eyes pterygium was larger than 3 mm in size, fleshy and vascularised. Senile cataract included 14 eyes of immature cataract [Table - 2].
All the patients were operated after confirming normalcy of blood pressure, sac patency, intraocular tension and post-lunch blood sugar. Operations were done under local anaesthesia with facial and retrobulbar injections. Initially, pterygium excision was done by performing a superficial keratectomy and creating an area of bare sclera. Strontium-90 applicator was used for 3 minutes duration over the site of pterygium to deliver 500 rads of beta radiation intra-operatively. Next a limbal section for cataract extraction was performed and the lens was extracted either by intracapsular or extracapsular technique and a peripheral iridectomy was done. Wound closure was done with 8-0 black silk sutures. Additional and deeper sutures were taken in the region of the bare sclera to ensure perfect wound approximation. This was essential because in this area of pterygium excision, conjunctival flap was missing resulting in a weakened support.
Postoperatively, these cases were hospitalised for three days and administered oral antibiotics for 3 days and topical 1% cyclogyl eye drops at night and 0.1% betamethasone eye drops 3 times a day for 3 months. The patients were followed up at weekly intervals for the first month, at the end of which the 8-0 sutures were removed. Later, the patients were followed up at two weekly intervals for the next 5 months to determine visual recovery. Postoperative retinoscopy was carried out to assess presence of astigmatism.
Of the twenty - three patients with vascularised pterygium larger than 3 mm in size and senile cataract, 12 patients (52%) had visual recovery to 6/12 while, all the patients (100%) with atrophic pterygium and senile cataract had visual recovery to 6/12 at the end of 6 weeks. Thus, 19/30 patients had visual recovery to 6/ 12. [Table - 3]
During the 6 months follow-up, no recurrence of pterygium was observed in 7 patients with atrophic pterygium and 11 patients with vascularised pterygium (total 60%). An avascular, flat pterygium smaller in size than the original pterygium reappeared in 8/30 patients (26%) while in 4 patients (14%) a vascularised thick pterygium of the same size as the one excised recurred within 6 weeks of operation. None of the patients had recurrence larger in size than the excised pterygium. No case of delayed recurrence was found at 6 months follow-up.
Visual recovery at 6 weeks and 6 months were almost comparable. Post-operative retinoscopy revealed that 17 patients had with the rule astigmatism at 6 weeks post-operatively [Table - 4] and 13 (43%) of them had with the rule astigmatism at 6 months. The mean postoperative astigmatism with the rule at 6 months was 1.3 D. Postoperative against the rule astigmatism was observed in 17 patients at the end of 6 months with a mean of 1.2 D.
No vitreous loss was observed in cataract surgery with this combined procedure. Further, the operative use of 500 rads of this combined beta radiation and post-operative topical steroids did not result in scleral necrosis, indolent corneal ulcer, or shallow anterior chamber during the 6 months follow-up.
The visual recovery in the combined pterygium and cataract procedure showed that 19 of 30 patients (63%) had 6/12 vision, 6 months postoperatively.
In this study, intra-operative beta radiation and post-operative topical steroids completely prevented recurrences in 7 patients of atrophic pterygium and 11 of vascularised pterygium. Incidence of recurrence observed in this study was 40%. Similar studies pterygium excision and beta radiation conducted by Nowell, Lewallen, Young-son had recurrence rates of 55%, 37% and 37% respectively.
The high rate of recurrences of pterygium in this study could be attributed to a declining beta radiation applicator output.' Only 500 rads of beta radiation were administered in our study. Also, in order to reduce beta radiation effect to the minimum, the applicator was not moved back and forth along the operation site at the limbus. Due to minimum beta radiation exposure, complications like scleral necrosis and indolent corneal ulcer have not been recorded in our study.
This study also shows that all recurrences manifest during the first 6 weeks as reported earlier by Lewalien and no late recurrences were recorded during the follow-up of 6 months. In spite of recurrences, 7 patients of 12 cases of recurrence i.e. 58%) had 6/24 or better visual recovery at 6 months follow-up.
Reduction in the rate of recurrence is possible by either using a higher dose of beta radiation intra-operatively or by using topical mitomycin-C 0.02% twice daily post-operatively,. Also the conjunctival autograft transplant,, technique can be used to prevent recurrences. Argon laser therapy, post-operatively of the new formed vessel on the scleral side of limbus can be used to reduce the rate of pterygium recurrence. How ever in this study only low dose beta radiation and topical steroids have been evaluated for their effect on the prevention of recurrences.
The combined procedure did not interfere with the healing of the cataract incision and complications such as shallow anterior chamber, iris prolapse and hyphema were not noted in our study. Usually after 6 weeks-6 months of conventional cataract surgery, the patients develop 2 diopters against the rule astigmatism. However, after the combined procedure in this study in-spite of the lamellar keratectomy done for pterygium excision and limbal incision for cataract extraction, none of the 30 patients had astigmatism greater than 2 diopters. This is due to the fact that additional deeper sutures were taken in the region of the excised pterygium which effectively countered against the rule astigmatism usually produced after cataract extraction. In our study after 6 months follow-up, the mean with the rule astigmatism was 1.3 diopters and the mean against the rule astigmatism was 1.2 diopters respectively.
The combined operative procedure is recommended as it is the only operative technique by which full visual recovery is possible in cases of large and vascularised pterygium with advanced cataracts. Either pterygium excision or cataract extraction done singly cannot restore full visual recovery in such cases. Further since the procedure is performed at one sitting it is time saving, cost effective and particularly relevant in .the Indian subcontinent where both the incidence of pterygium and senile cataract are higher than elsewhere.
The low dose of beta radiation used intra-operatively and postoperative topical steroids does not interfere with the results of cataract surgery and yet completely prevents recurrences of pterygium in 60% patients and reduces the size of recurrence in another 26%. The additional, deeper sutures in the region of the excised pterygium effectively reduces the against the rule astigmatism which usually occurs after conventional cataract surgery.
But the limitation of this combined procedure is that higher doses of beta radiation above 500 rads cannot be used. Perhaps a future study employing Argon laser therapy postoperatively along with this combined procedure could be evaluated for its efficacy in reducing the pterygium recurrence rate.
[Table - 1], [Table - 2], [Table - 3], [Table - 4]