Macular translocation with folding produces different anatomic configuration than MT with retinotomy

A study finds dissimilar secondary visual effects among three techniques.

Issue: May 1, 2001

ByBob Kronemyer

DURHAM, N.C. — In a comparison of three techniques for macular translocation surgery, macular translocation with 360° retinotomy produced the greatest linear and angular displacement compared to either scleral outfolding or scleral infolding. Conversely, macular translocation with scleral folding produced smaller displacement, greater relative macular distortion and metamorphopsia.

"Macular translocation (MT) surgery remains a complex procedure with outcomes that may vary by surgeon," said Cynthia A. Toth, MD, an associate professor of ophthalmology at Duke University Eye Center here.

"The surgery has not been evaluated in randomized, clinical trials. However, in our consecutive series of patients undergoing MT 360 retinotomy or MT scleral infolding, results are promising. This is noteworthy considering the size of the pathology in the MT 360 eyes with regard to visual outcomes. Therefore, a randomized trial of MT 360 retinotomy versus observation for patients not eligible for approved clinical therapies would be appropriate."

Macular translocation (MT) with 360° retinotomy was more likely to cause retinal detachment, macular pucker, cystoid macular edema and tilted vision requiring surgery. In contrast, MT with either scleral infolding or outfolding was more likely to result in recurrence of CNV beneath the foveal center.

Dr. Toth headed up a study of 52 consecutive patients at Duke Eye Center who underwent MT surgery with either scleral infolding or 360° retinotomy. There was also a retrospective review of an additional 11 patients who had MT surgery with scleral outfolding.

For the prospective study, patients underwent standardized visual acuity testing. In addition, “all patients had their fluorescein angiogram digitized so we could then overlay the prints to look at the angle, distance and distortion of the central retina,” Dr. Toth said. Patients were assigned to one of the two surgical groups based on the distance from the foveal center to the inferior border of the lesion.

Disc area ring

For both scleral folding groups (one prospective, the other retrospective), patients had a 3.5 disc area ring radius, according to guidelines from the Macular Photocoagulation Study (MPS). "The distance from fovea to the inferior margin was less than or equal to the 3.5 MPS disc area," Dr. Toth said. But for MT with 360° retinotomy, all patients had greater than 3.5 MPS disc diameter.

For the two folding groups, the median inferior distance to the inferior margin of the choroidal neovascularization (CNV) was between 1 and 2 MPS disc areas. In the 360° retinotomy group that distance was roughly 6 MPS disc diameters, translocated superiorly.

"The median translocation of the MT with 360 retinotomy was greater than the radius of a 12 MPS disc diameter. The MT scleral infolding was greater than 2 and the MT scleral outfolding greater than 1," Dr. Toth said.

Impact on visual acuity

"Both by the most recent visual acuity score, and with change in distance visual acuity, we found that distance of translocation beyond the CNV margin was a significant predictor of postoperative visual acuity in both the scleral infolding and the 360 retinotomy group, combined and separately," Dr. Toth said.

"Looking only at the patients in these two groups who had standardized visual acuity (median 10 months postop; range 6 to 12 months), there was less than three lines of vision lost after MT in the scleral infolding group, and less than one line median visual acuity loss in the 360 retinotomy group," she said.

Overall, 24% of patients with MT scleral infolding achieved a visual acuity of 20/100 or better, compared to 35% in the 360° retinotomy group.

"The difference in visual acuities -- pre, post and changes--were not statistically significant when these groups were compared. This was despite the relatively larger preoperative lesion size in the 360° retinotomy group," she said.

Rotation angle

Similarly, results were comparable between MT with scleral outfolding and MT with scleral infolding for angle of rotation (from preop to postop and to distance of movement). However, greater distortion appeared to be associated with greater distance in translocation, even among scleral infolding patients without a macular fold. "But this was not statistically significant with the image processing techniques we used to analyze movement," Dr. Toth said.

A much larger angle of movement was found in patients who had undergone MT with 360° retinotomy. "We still had minimal distortion of the macular topography. Despite a large angle of movement, results were very similar across the board when we looked at our distortion scale."

Regarding complications, MT with 360° retinotomy was more likely to cause retinal detachment, macular pucker, cystoid macular edema and tilted vision requiring surgery. In contrast, MT with either scleral infolding or outfolding was more likely to result in recurrence of CNV beneath the foveal center. "There was also lesser distance from that margin of the CNV after translocation in the two folding groups," Dr. Toth said. Further, the folding groups had a greater likelihood of a retinal fold in the macula and an increased incidence of corneal astigmatism in the infolding group only.

The investigators also found a greater distance of MT away from the margin of the CNV. “This was associated with better visual outcome in MT with 360 retinotomy for large CNV, as well as in MT with scleral infolding for small CNV,” Dr. Toth said.



Macular translocation with scleral outfolding (1a), with scleral infolding (1b) and with 360º retinotomy (1c).

Macular translocation with scleral outfolding at preop 20/80 (2a) and postop 20/60 (2b).

Macular translocation with scleral infolding at preop 20/160 (3a) and postop 20/50 (3b).

Macular translocation with 360º retinotomy at preop 20/50 (4a) and postop 20/40 (4b).

For Your Information:

Cynthia A. Toth, MD, can be reached at Duke Eye Center, Box 3802, Durham, NC 27710; (919) 684-5631; fax: (919) 681-6474; e-mail: cynthia.toth@duke.edu.