The efficacy of biofeedback visual rehabilitation therapy in patients with infantile nystagmus syndrome: A retrospective study.

OBJECTIVE: To report fixation stability changes in patients with different forms of infantile nystagmus syndrome (INS), who have undergone a visual rehabilitation through biofeedback fixation training (BFT) with microperimetry (MP). DESIGN: Retrospective study. METHODS: Patients 6 to 12 years-old with INS who performed BFT with MP. Initially 10 once-weekly followed by eight twice-weekly sessions of BFT during a minimum of 6 months period were performed. Visual acuity (VA) and MP fixation stability indices were analyzed, including displacement from fixation point (P1, P2) and percentage of retinal loci used during fixation attempt (BCEA 63% and 95%). Statistical analysis was conducted at baseline (BL), 10 weeks (W10) and 6 months (M6). RESULTS: Twelve patients (mean age 8.9 years.) with INS completed the whole training session. All patients showed significant improvement in the mean BCEA fixation area (deg2): For BCEA@95% BL was 78.0, 46.1 at W10, and 27.4 at M6 (p-value = 0.004). For BCEA@63% BL was 27.3, 15.4 in W10, and 9.17 at M6 (p = 0.01). The ANOVA test for the FS indices of P1 and P2, as well as for BCVA showed no significant difference when compared at the same intervals. CONCLUSION: Fixation stability (FS) indices of BCEAs (63% and 95%) improved at W10 and M6, while P1 and P2 showed significant improvement at W10 but not at M6, probably because BCEA involves a much larger area than P1 and P2. VA did not show significant improvement at any time point.

Biofeedback fixation training method for improving eccentric vision in patients with loss of foveal function secondary to different maculopathies.

PURPOSE: Fixation stability (FS) of the preferred retinal locus (PRL) may be improved by biofeedback fixation training (BFT) with microperimetry. Such training can be done on the patient's PRL or in different retinal loci with better functional characteristics. We studied both options and compared the outcomes. METHODS: Sixty-seven consecutive patients with bilateral central vision loss, poor FS and visual acuity (VA) lower than 0.3 LogMAR were recruited for BFT with microperimeter. Patients were assigned into 2 groups. In group A, BFT was performed on the patient's spontaneous PRL. In group B, PRL was located between 2 adjacent loci with the highest light sensitivity and the lowest distance from the fovea. Two sets of 12 weekly BFT sessions were performed. Primary outcomes were: FS, VA and reading speed. RESULTS: Outcomes were statistically significantly better in group B. Mean percentage of FS at therapy end improved from 32 to 35% for group A and from 40 to 55% in group B. Mean VA improved from 1 to 0.86 in group A and from 1 to 0.84 in group B. Reading speed (wpm) improved from 56 to 58 in group A and from 63 to 89 in group B. CONCLUSIONS: This study describes a reliable methodology of improving eccentric fixation stability using BFT in microperimetry, when the fixation training locus is individualized as the retinal area with best functional characteristics. Further studies are needed to validate its value in a larger scale of patients, at different stages of the disease, and its persistence over time.

Bilateral eccentric vision training on pseudovitelliform dystrophy with microperimetry biofeedback.

Low vision patients with eccentric viewing (EV) use extrafoveal retinal areas to compensate for the loss of central vision. Such retinal loci are known as the preferred retinal locus (PRL). It is known that EV is accompanied by unstable fixation. Microperimetry systems with biofeedback training have been used as a rehabilitation aid to improve fixation stability in EV patients. Normally, only the best or dominant eye is selected for such rehabilitation. This case report describes the rehabilitation on both eyes by means of PRL relocation with MAIA microperimetry (Centervue, Padova, Italy) with biofeedback training technology of a 74-year-old woman diagnosed with adult pseudovitelliform dystrophy. The patient presented binocularly similar anatomical and functional characteristics with the PRL located over the dystrophic area. At the end of the 3 months rehabilitation period, the PRL was successfully relocated inferiorly from the fovea showing relevant visual acuity improvement.