Retinal detachment after resection of choroidal melanoma is less frequent, less threatening

Constant improvements in this branch of ocular surgery have made retinal detachment more easily treatable and more often preventable.

Issue: November 1, 2000

TAORMINA, Italy - Rhegmatogenous retinal detachment after local resection of choroidal melanoma has an incidence of about 18%. It is more common with thick tumors, and it is usually treatable, but it is also preventable by immediate intraocular surgery. This emerged from recent findings presented at the Jules Gonin meeting by Bertil Damato, MD, of Liverpool University Hospital, U.K.

"Today's data are reassuring, considering that, some years ago, Wallace Foulds and I reported an incidence of about 30%," Prof. Damato said. "More recently, I engaged in a retrospective study of 156 patients treated for choroidal melanoma between January 1993 and June 2000. These patients were about 12% of the total number of cases we had treated for choroidal melanoma during this time. Data were collected prospectively and saved in a computerized database. In July 2000, we downloaded and analyzed them using SPSS. The median follow-up was 2.3 years."

Higher incidence with thicker tumors

photograph ---A local resection in progress. Transscleral local resection involves the creation of a lamellar scleral flap, ocular decompression, tumor resection (if possible, avoiding retinal damage), hypotensive anesthesia and adjunctive plaque radiotherapy.

As Prof. Damato explained, transscleral local resection involves the creation of a lamellar scleral flap, ocular decompression, tumor resection (if possible, avoiding retinal damage), hypotensive anesthesia and adjunctive plaque radiotherapy.

"The operation takes about 3 hours and is reserved for tumors we consider too large for radiotherapy," he said.

In his study, the largest basal tumor diameter averaged 13.5 mm, and the mean thickness was 8.4 mm. The incidence of retinal detachment according to tumor thickness was measured.

"If the tumor thickness was less than 10 mm, the rate was about 13%. If the thickness was 10 mm or more, the rate increased to about 40%. This high incidence is probably due to the fact that thick tumors are more likely to be adherent to the retina than thin tumors," Prof. Damato said.

Men were shown to have a significantly greater incidence of retinal detachment than women.

"I'm not quite sure why this is," he observed. "In the same way, patients from overseas had a greater incidence than those living in Britain. In this case, they were generally more highly motivated to keep the eye even in presence of a difficult or borderline tumor."

Visual acuity results

photograph ---A choroidal melanoma in the right eye before treatment.

Of the 156 patients treated with transscleral local resection, 28 (18%) had retinal detachment.

Two of them underwent primary enucleation, one was left untreated because the detachment was localized and stable and 25 underwent retinal detachment surgery. Ten of these subsequently lost the eye, mostly because of tumor recurrence and persisting retinal detachment, said the surgeon.

Sixteen eyes were conserved, with visual function ranging from 6/9 to light perception.

Prof. Damato also showed the results on visual acuity according to retinal detachment, tumor recurrence, both of these or neither of these complications.

"In the 105 patients with none of these complications, about 35% had vision of 6/12 or better, 35% had 6/18 to 6/60, 20% had counting fingers vision, mostly due to macular excision, and 20% had poor vision. Only one of these eyes was enucleated. In contrast, most of the 21 eyes with retinal detachment were lost, most of the 23 eyes with tumor recurrence had poor vision and seven eyes with both of these complications did very poorly indeed," he said.

Constant improvements

photograph ---The final surgical result.

Prof. Damato pointed out the developments that, over the years, have aimed more and more at sparing ocular structures and preventing retinal detachment.

"If retinal detachment is now a less frequent and less threatening event, it is thanks to the constant improvements we have made in this branch of ocular surgery," he said.

Previously, retinal prolapse through the scleral windows made it very difficult to cut the posterior choroid without damaging the retina. Around 1985, he recalled, together with Wallace Foulds, he started collapsing the eye by limited pars plana vitrectomy, and this greatly reduced the incidence of retinal tears.

In the past, tumors were excised with wide surgical clearance margins to prevent recurrence.

"Nowadays, we routinely perform adjunctive plaque radiotherapy so that it is possible to conserve iris and ciliary body, reducing ocular morbidity."

Also, iridocyclochoroidectomy used to be performed from front to back, so that the ciliary epithelium was usually lost, thereby causing retinal dialysis and detachment. "Now, we perform it from back to front, so that most of the ciliary epithelium is conserved. This seems effective for preventing retinal detachment. For this reason, tumor extension anterior to ora serrata is no longer an adverse prognostic factor as it used to be."

In the past, complete excision was attempted in all patients, so that if the tumor was adherent to the retina, a retinal defect was created. "Now, any tumor that is adherent to the retina is left in situ and treated with radiotherapy. This is a recent development, so that encouraging results are only anecdotal. I hope that we can one day evaluate its efficacy in a statistic fashion," Prof. Damato said.

"Finally, in the past, when a retinal tear was created, we attempted to prevent retinal detachment using gas tamponades, plombs and encirclements. Today, retinal detachment is prevented by promptly performing total vitrectomy with endolaser and silicone oil. So far, this technique has been carried out on 11 patients, and only one has subsequently developed retinal detachment," he said.

For Your Information:
Bertil Damato, MD, can be reached at the Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK; 0044 151 706 3973; fax: 0044 151 706 5436; e-mail: bertil.damato@btinternet.com. Dr. Damato does not have a direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any company mentioned.