Case selection in macular relocation surgery for age related macular degeneration

Abstract

Background: To date there has been no randomised controlled trial demonstrating the safety and efficacy of macular relocation surgery (MRS) for age related macular degeneration (AMD). Vision can be improved in some patients and made worse in others despite successful surgery or because of complications.

Purpose: To determine which patients would benefit from MRS.

Methods: Twenty nine patients with exudative AMD took part in a prospective, non-comparative, interventional study. Macular relocation surgery involved phacoemulsification, vitrectomy, 360 degrees retinotomy, excision of choroidal neovascular membrane, and macular relocation using an infusion of 5-fluorouracil and low molecular weight heparin as adjuvant to prevent proliferative vitreoretinopathy. Patients underwent protocol refraction preoperatively and six-monthly postoperatively by designated optometrists. Preoperative fundus fluorescein angiograms were read by masked observers and the lesions were classified according to a set protocol. The main outcome measures were visual improvement, final vision of better than 20/400, reading speed, critical print size. Logistic and multiple stepwise linear regressions were used to identify independent factors which predicted the main outcomes.

Results: Preoperative visual acuity (20/120 or worse) and lesion type (predominantly classic or submacular haemorrhage) were significantly associated with visual improvement (coefficient of regression B = 26.8, p<0.001 and B = 14.9 with p = 0.045 respectively). There were no significant independent factors which predicted a final distance logMAR visual acuity of 1.3 (20/400) or any arbitrary definition of blindness.

Conclusions: The study showed that it was possible to select cases that were more likely to experience an improvement in vision following MRS.

Figure 1

The light pipe is used as a scleral indentor. The transilluminated light provides good illumination for trimming the vitreous base and carrying out the 360° retinotomy, and enables the surgeon to carry out these procedures bimanually with better control.

Figure 2

(A) A plot of preoperative against six months logMAR visual acuity. Red triangles, haemorrhagic lesions; black squares, predominantly classic lesions; blue circles, minimally classic lesions. The diagonal line is the line of no change. Patients with improvement are shown above and to the left of this line. (B) The same plot showing selection of patients. The vertical line is the preoperative visual cut off of 0.78. Patients to the left of this line are selected. Solid symbols, patients selected; empty symbols, patients not selected. By selecting all predominantly classic and haemorrhagic cases with a preoperative vision of 0.78 or worse, all patients with visual improvement are included and all but two patients with visual deterioration are excluded.

Figure 3

Survival defined as not having lost 15 or more letters at the final follow up visit.

Figure 4

Plotting change in logMAR visual acuity against preoperative logMAR visual acuity. Note with logMAR vision any improvement is negative. Thus, patients above the x axis had improvement and below had deterioration. The trend line has a negative slope, suggesting that the worse the preoperative vision, the greater the improvement.