Use of prisms for vision rehabilitation after macular function loss may impact oculomotor control.

OBJECTIVE

To determine the effect from using prisms for image relocation on fixation stability estimates in low-vision (LV) patients with age-related macular degeneration (AMD).

METHODS

The study was designed as a prospective, nonrandomized, observational case series. Inclusion criteria included documented AMD, LV with best corrected visual acuity of 20/50 to 20/400 in the better eye, and cases wearing distance glasses with prisms for image relocation incorporated in the glasses. Preferred retinal locus (PRL) and fixation stability were assessed using the Nidek MP1 and MAIA microperimeters. A control group was used to compare results.

RESULTS

We recruited 14 study subjects with AMD and 10 with no retinal pathology serving as a control group. On average, 6 (SD 2) prisms diopters were prescribed to all in distant viewing glasses. Fixation stability was better at 3-month interval from baseline (p = 0.021) in the AMD group and stayed the same for the following 9 months. No change in fixation stability was noticed in the control group. There was no statistically significant difference in PRL eccentricity between the 3- and 12-month intervals in the AMD group (p = 0.39). However, there was a positive correlation between PRL eccentricity and baseline bivariate contour ellipse area in the AMD group (p = 0.052).

CONCLUSIONS

Patients with LV with AMD who are using prisms for image relocation toward the peripheral retinal exhibit better fixation stability than those who are not using prisms. Better fixation stability may impact on other visual outcomes. Use of prisms should be considered in any LV rehabilitation attempt and used in conjunction with other modern interventions in LV rehabilitation.