PREFERRED RETINAL LOCUS LOCATIONS IN AGE-RELATED MACULAR DEGENERATION

Visual field asymmetries in visual word form identification

Visual performance across the visual fields interacts with visual tasks and visual stimuli, and visual resolution decreases as a function of eccentricity, varying at isoeccentric locations. In this study, we investigated the extent of asymmetry and the rate of change in visual acuity threshold for visual word form (VWF) identification at horizontal and vertical azimuths across the fovea, and at eccentricities of 1°, 2°, 4°, 6° and 8° for 10%, 20%, 40%, and 80% contrast levels, to determine whether and how the eccentricities, meridians, and contrasts modulated the VWF identification acuity threshold. The stimuli were 16 traditional Chinese characters of similar legibility. Participants pressed a key to indicate the character presented, either monocularly or binocularly, at one of 21 randomly selected locations. A staircase procedure was used to determine the threshold, and a multiple linear regression model was used to fit the linear cortical magnification factor (CMF). We found that (1) the asymmetry was most pronounced on the vertical and superior azimuths, (2) the asymmetry between the right and left azimuths was not significant, (3) the CMF was significantly smaller on the vertical azimuth than on the horizontal azimuth, (4) the CMF was smaller on the superior vertical azimuth than on the inferior azimuth, and (5) monocular viewing and low contrast enhanced the CMF difference between azimuths. In conclusion, vertical and horizontal azimuths, location of eccentricity, contrast levels of word symbols, and monocular/binocular viewing have different effects on visual field asymmetry and cortical magnification factors.

Eccentric Viewing Training for Age-Related Macular Disease: Results of a Randomized Controlled Trial (the EFFECT Study)

Purpose

Eccentric viewing training for macular disease has been performed for > 40 years, but no large studies including control groups have assessed the benefits of this training. The EFFECT (Eccentric Fixation From Enhanced Clinical Training) study is a large randomized controlled trial of 2 types of eccentric viewing training.

Design

Randomized controlled trial.

Participants

Two hundred adults with age-related macular disease.

Methods

Participants were randomized to either of the following: (1) a control group; (2) a group receiving supervised reading support; (3) a group receiving 3 sessions of training to optimize the use of their own preferred retinal locus; or (4) a group receiving 3 sessions of biofeedback training of a theoretically optimal trained retinal locus. All participants received standard low-vision rehabilitation.

Main Outcome Measures

The primary outcome was patient-reported visual task ability measured on the Activity Inventory instrument at goal level. Secondary outcomes included reading performance and fixation stability.

Results

There was no difference between groups on change in task ability (F(3,174) = 1.48, P = 0.22) or on any of the secondary outcome measures. Visual acuity and contrast sensitivity fell in all groups, suggesting that disease progression outweighed any benefit of training.

Conclusions

Eccentric viewing training did not systematically improve task ability, reading performance, or fixation stability in this study. Our results do not support the routine use of eccentric viewing training for people with progressing age-related macular disease, although this training may help people with end-stage disease. Rehabilitation of an inherently progressive condition is challenging.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

What Is a Preferred Retinal Locus?

This review examines the concept of the preferred retinal locus (PRL) in patients with macular diseases. Considering monocular and binocular viewing, we (a) explain how to identify the PRL and discuss the pitfalls associated with its measurement, (b) review the current hypotheses for PRL development, (c) assess whether the PRL is the new reference point of the ocular motor system, and discuss (d) the functional and (e) the clinical implications of the PRL. We conclude that the current definition of the PRL is probably incomplete and should incorporate the need to evaluate the PRL in the framework of binocular viewing. We emphasize the need for more research.

Biofeedback Training after Successful Inverted Internal Limiting Membrane (ILM)-Flap Technique for High Myopic Macular Hole

BACKGROUND

Microperimetric biofeedback training improved visual acuity and fixation stability in patients who previously underwent macular surgery. We aimed to compare the functional results of biofeedback training with the standard of care in patients who underwent successful inverted Internal Limiting Membrane (ILM)-flap technique for high myopic macular holes (hMMH).

METHODS

This was a retrospective, comparative, cohort study. Patients with hMMH after surgical hole closure underwent microperimetric biofeedback using structured light stimulus plus acoustic tone (n = 12; Biofeedback) or standard of care with scheduled visits (n = 11; Control). Best-corrected visual acuity, retinal sensitivity at central 12° (RS) and 4° (CRS) with a mean deviation at central 12° (MD), and fixation stability as bivariate contour ellipse area (BCEA 68%, 95%, and 99%) were assessed at baseline and month 1, 3, 6, and 12. The Mann-Whitney test was used to test the difference between the groups.

RESULTS

Baseline functional parameters were not significantly different among the groups. BCVA significantly improved in each group (Biofeedback, p = 0.002; Control, p ≤ 0.02) at all follow-up visits. CRS significantly improved at 6 (p = 0.03) and 12 (p = 0.01) months in the Biofeedback group and at month 12 (p = 0.01) in the Control group. RS (p = 0.001) and MD (p = 0.005) improved at the last follow-up only in the trained group. After training, BCEA 68% and 95% significantly improved (6 and 12 months, p < 0.05). The Biofeedback group had better results in RS (p ≤ 0.02), CRS (p ≤ 0.02), and BCEA 68%, 95%, and 99% (p ≤ 0.01) compared to the Control at all follow-ups. BCVA and MD were better in the Biofeedback group at month 3 (p = 0.01), and month 3 (p = 0.01) and 12 (p = 0.003), respectively.

CONCLUSIONS

Microperimetric biofeedback can increase retinal sensitivity and stabilize fixation better than the standard care over months after a successful inverted ILM-flap for hMMH.

Evaluation of fixation characteristics in amblyopia using microperimetry

PURPOSE

To evaluate fixation characteristics in amblyopia using macular analyzer integrity assessment (MAIA) microperimetry and to investigate the factors affecting fixation stability.

METHODS

This prospective, cross-sectional study enrolled a total of 58 amblyopic patients who were between 8 and 55 years old. Average threshold macular sensitivity (AT) and fixation characteristics were assessed using MAIA microperimetry. Two Bivariate contour ellipse area (BCEA) fixation indices (63% and 95% proportional values) and the percentage of fixation points within 1° and 2° from the fovea (P1 and P2) were used to assess fixation stability. Non-amblyopic fellow eyes were used as the control group for comparison.

RESULTS

AT and fixation stability indices (P1, P2, BCEA 63%, BCEA 95%) were worse in the amblyopic eyes than in the fellow eyes (p < 0.05, for all indices). There was a moderate positive correlation between best corrected visual acuity (BCVA), and AT, and P2, and a moderate negative correlation between BCVA, and BCEA indices. 48% of the eyes were eccentrically fixating (the percentage was 25% in the anisometropic group, 52% in the strabismic group, and 69% in the combined group) and 32% in the non-amblyopic eye (p = 0.052). The preferred fixation eccentricity in amblyopic eyes was significantly greater than the non-amblyopic eyes (p = 0.004), and there was a negative correlation between preferred fixation eccentricity and BCVA (p = 0.012, r = - 0.327).

CONCLUSIONS

Our data showed a decrease in fixation stability, a positive correlation between fixation stability and BCVA, and a negative correlation between preferred fixation eccentricity and BCVA in amblyopic eyes.

The intraocular implant and visual rehabilitation improve the quality of life of elderly patients with geographic atrophy secondary to age-related macular degeneration

INTRODUCTION

The objective of this prospective study was to evaluate the effects of intraocular macular lens implantation and visual rehabilitation on the quality of life of patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD).

METHODS

Patients with bilaterally decreased near vision (not better than 0.3 logMAR with the best correction), pseudophakia, were included in the project. The Scharioth macula lens (SML) was implanted into the patients' better-seeing eye. Intensive visual rehabilitation of the ability to perform nearby activities was performed for 20 consecutive postoperative days. All subjects were examined before and after SML implantation ophthalmologically. The National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25) was administered before and 6 months after surgery.

RESULTS

Twenty eligible patients with mean age 81 years (63 to 92 years) were included in the project: 7 males and 13 females. Nineteen of them completed the 6-month follow-up. Near uncorrected visual acuity was 1.321 ± 0.208 logMAR before SML implantation and improved to 0.547 ± 0.210 logMAR after 6 months (dz =  - 2.846, p < 0.001, BF₁₀ = 3.29E + 07). In the composite score of the NEI VFQ-25, there was an improvement in the general score and the specific domains related to the implantation. Participants reported fewer difficulties in performing near activities (dz = 0.91, p = 0.001, BF₁₀ = 39.718) and upturns in mental health symptoms related to vision (dz = 0.62, p = .014, BF₁₀ = 3.937).

CONCLUSION

SML implantation, followed by appropriate rehabilitation, improved near vision and increased the quality of life of visually handicapped patients with AMD in our project.

Oculomotor changes following learned use of an eccentric retinal locus

People with bilateral central vision loss sometimes develop a new point of oculomotor reference called a preferred retinal locus (PRL) that is used for fixating and planning saccadic eye movements. How individuals develop and learn to effectively use a PRL is still debated; in particular, the time course of learning to plan saccades using a PRL and learning to stabilize peripheral fixation at the desired location. Here we address knowledge limitations through research describing how eye movements change as a person learns to adopt an eccentric retinal locus. Using a gaze-contingent, eye tracking-guided paradigm to simulate central vision loss, 40 participants developed a PRL by engaging in an oculomotor and visual recognition task. After 12 training sessions, significant improvements were observed in six eye movement metrics addressing different aspects involved in learning to use a PRL: first saccade landing dispersion, saccadic re-referencing, saccadic precision, saccadic latency, percentage of useful trials, and fixation stability. Importantly, our analyses allowed separate examination of the stability of target fixation separately from the dispersion and precision of the landing location of saccades. These measures explained 50% of the across-subject variance in accuracy. Fixation stability and saccadic precision showed a strong, positive correlation. Although there was no statistically significant difference in rate of learning, individuals did tend to learn saccadic precision faster than fixation stability. Saccadic precision was also more associated with accuracy than fixation stability for the behavioral task. This suggests effective intervention strategies in low vision should address both fixation stability and saccadic precision.

Effects of Ectopic Inner Foveal Layers on Foveal Configuration and Visual Function after idiopathic Epiretinal Membrane Surgery

PURPOSE

To investigate the effects of ectopic inner foveal layers (EIFLs) on foveal configuration recovery and visual acuity (VA) after idiopathic epiretinal membrane (iERM) removal and analyze the relationship of foveal configuration recovery between 1-month and long-term postoperatively.

METHODS

This retrospective study included 216 consecutive eyes with iERM that underwent vitrectomy surgery. A comprehensive ophthalmic examination was performed for all patients before and 1, 4,10, and 24 months after surgery. We observed the postoperative anatomical and functional recovery of eyes with and without EIFLs and analyzed the association between short-term and long-term anatomical recovery.

RESULTS

The presence of EIFL was associated with severe preoperative visual damage (P＜0.001) and was considered as a negative factor for postoperative foveal depression recovery (P＜0.001). No significant difference was found in postoperative BCVA between the eyes with and without EIFLs (P=0.442). For eyes with stage II ERMs, 17.6% developed EIFLs postoperatively, which did not affect the final BCVA. Overall, 24.5% of ERMs restored the foveal configurations at 1 month postoperatively, and 14.7% continued recovering during the follow-up. Foveal structure recovery in eyes with EIFLs was associated with earlier stage, fewer microcystic macular edema, complete IZ layer, and a thinner CFT (All P＜0.05) at 1-month postoperatively.

CONCLUSIONS

The EIFL is associated with severe preoperative visual damage and is a negative factor for postoperative anatomical recovery, but it is a minor factor for postoperative VA. We also found an association of foveal configuration recovery between 1-month and long-term after surgery.

Changes of Fixation Stability and Location after Epiretinal Membrane Surgery

PURPOSE

The study aimed to evaluate fixation stability and position changes after epiretinal membrane (ERM) surgery.

METHODS

This is a retrospective study that included 60 consecutive eyes with idiopathic ERM. All patients received comprehensive ophthalmic examinations preoperatively and 1, 4, 10 months postoperatively. Main outcome measures included fixation stability and position, bivariate contour ellipse area (BCEA), and preferred retinal locus (PRL).

RESULTS

The number of patients with stable fixation as well as predominantly central fixation was increased significantly after ERM surgery (61.7% vs. 73.3%, P=0.001; 41.7% vs. 71.7%, P=0.037). The correlation analysis showed that the preoperative factors associated with improved postoperative fixation stability were a larger BCEA value (P<0.001), poorer visual acuity (P=0.002), advanced stage (P=0.002), thicker CFT (P=0.015), and a longer PRL-foveal distant (P=0.0025). As for improved fixation location, the associated preoperative factors were age (P=0.003), CFT (P=0.044) and PRL-foveal distant (P<0.001).

CONCLUSION

Our observations point to the changes of fixation parameters in patients after ERM surgery. We found that patients with preoperative unstable, eccentric fixation and poor BCVA can significantly benefit from the surgery. This result indicates that even in patients with severe macular damage, the ERM surgery still has great benefits in recovering visual function.

Binocular visual function and fixational control in patients with macular disease: A review

For normally sighted observers, the centre of the macula—the fovea—provides the sharpest vision and serves as the reference point for the oculomotor system. Typically, healthy observers have precise oculomotor control and binocular visual performance that is superior to monocular performance. These functions are disturbed in patients with macular disease who lose foveal vision. An adaptation to central vision loss is the development of a preferred retinal locus (PRL) in the functional eccentric retina, which is determined with a fixation task during monocular viewing. Macular disease often affects the two eyes unequally, but its impact on binocular function and fixational control is poorly understood. Given that patients’ natural viewing condition is binocular, the aim of this article was to review current research on binocular visual function and fixational oculomotor control in macular disease. Our findings reveal that there is no overall binocular gain across a range of visual functions, although clear evidence exists for subgroups of patients who exhibit binocular summation or binocular inhibition, depending on the clinical characteristics of their two eyes. The monocular PRL of the better eye has different characteristics from that of the worse eye, but during binocular viewing the PRL of the better eye drives fixational control and may serve as the new reference position for the oculomotor system. We conclude that evaluating binocular function in patients with macular disease reveals important clinical aspects that otherwise cannot be determined solely from examining monocular functions, and can lead to better disease management and interventions.

An Overview of Preferred Retinal Locus and Its Application in Biofeedback Training for Low-Vision Rehabilitation

Central vision loss (CVL) caused by macular damage generally disables common daily tasks, which cannot be reversed by present treatments. Fortunately, it has been found that biofeedback training by inducing or reinforcing preferred retinal locus (PRL) as an eccentric fixation reference contributes to the improvement of visual performance in patients with CVL. However, the clinical application is still under controversy due to poor knowledge of its fundamental and inconsistent practical standards. This article aims to summarize the possible rationale for the development, location, re-location and evaluating indicators of PRL, and the general apparatus, protocol, and outcome of biofeedback PRL training.

Characteristics of Preferred Retinal Locus in Eyes with Central Vision Loss Secondary to Different Macular Lesions

OBJECTIVE

Preferred retinal locus (PRL) training has been applied to low-vision rehabilitation for patients with central vision loss (CVL). This study aimed to explore the characteristics of a natural PRL in eyes with different macular lesions. The data may be useful in customizing training programs.

METHODS

A total of 72 eyes with CVL were included and assigned into two groups. In group A, 29 eyes diagnosed with macular holes featured relatively sharp borders and small areas of lesions. In group B, 44 eyes showed lesions characterized by irregular borders and large areas. The PRL location relative to a scotoma in the retina, fixation stability, and the average threshold surrounding the PRL were determined and compared between the two groups.

RESULTS

In group A, the PRL was located above in 48.28%, below in 27.59%, left in 62.07%, right in 31.03%, and inside in 3.45% of the eyes. In group B, the PRL was located above in 39.53%, below in 4.65%, left in 44.19%, right in 6.98%, and inside in 27.91% of eyes. The amount of retinal displacement occurring within 1° from an initial reference point (P< .05) and the 95% bivariate contour ellipse area (P< .05) in group A were respectively higher and lower than those in group B. However, the average thresholds around the PRLs in the two groups showed no significant difference (P > .05).

CONCLUSIONS

A PRL to the left of or above a scotoma tends to develop to avoid the right and inferior field defect, regardless of the scale and boundary of lesions. Although light sensitivity around a PRL shows no relation to lesion features, fixation stability is worse in irregular and large lesions.

How Much Do Clinical and Microperimetric Findings Affect Reading Speed in Low Vision Patients with Age-related Macular Degeneration?

Purpose: To investigate the factors affecting the reading speed of patients with central scotoma due to age-related macular degeneration (AMD).Materials and Methods: We included 63 eyes of 63 patients with AMD who applied to our low vision clinic between August 2018 and September 2019 in this prospective study. We evaluated socio-demographic characteristics, eye examination findings and Minnesota Low Vision Reading Test (MNREAD) results. We used the MAIA microperimeter device to evaluate the properties of the preferred retinal locus for fixation (PRL) of the patients. Evaluations included the assessment of the effects of all parameters on reading speed.Results: The PRL was most commonly in the nasal (31%) and superior (26%) quadrants. Twenty-nine percent of the cases preferred the left visual field. PRL localization had no effect on reading speed, whereas, fixation stability, educational status, presence of foveal absolute scotoma, reading acuity and duration of reading interruption were found to have the most significant effects. Multiple regression analysis showed that reading speed decreased by 67 units in the presence of unstable fixation, by 17 units in the presence of foveal absolute scotoma, by 3 units with every 0.1 increase in logMAR value, and by 1.7 units with every 1-year increase in reading interruption. Additionally, being a university graduate was associated with an increased reading speed (by 18 units)Conclusion: Increased reading performance is one of the factors that can improve quality of life. The factors found to affect the reading speed in the current study may guide the rehabilitation process in low vision patients.

Effectiveness of Low Vision Rehabilitation Using Microperimetric Acoustic Biofeedback Training in Patients with Central Scotoma

PURPOSE

To evaluate the efficacy of visual rehabilitation with microperimeter biofeedback in patients with central scotoma.

MATERIALS AND METHODS

35 consecutive patients with central scotoma (17 age-related macular degeneration (AMD), 14 Stargardt disease, and 4 cone dystrophy) were included in the study. Visual acuity, reading performance by Minnesota Low Vision Reading Test (MNREAD), quality of life by 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25), and fixation analysis by MAIA microperimeter were evaluated before and 1 month after training. The rehabilitation program consisted of 10 training sessions of 10 minutes.

RESULTS

The median best-corrected visual acuity (BCVA) was 0.80 logMAR (range 0.3 to 1.3 logMAR). Fifty-nine percent of patients with AMD developed a preferred retinal locus (PRL) nasal to the fovea, and 64% of the patients with Stargardt disease preferred a PRL superior to the fovea. The PRL location in 3 of 4 cone dystrophy patients was nasal to the fovea. The mean PRL distance from the fovea was 7.57 ± 3.61 degrees. Fixation stability improved with P1 values of 22.34 ± 11.81 versus 32.05 ± 18.79 (p = .003) and 95% bivariate contour ellipse area (BCEA) values of 41.6 versus 23.6 (p = .018) before and after training, respectively. There was a significant difference in reading acuity between before and after training (p = 0.008). The overall score and near activities score of NEI VFQ-25 were found to be increased at the end of the rehabilitation (p < 0.001).

CONCLUSION

Rehabilitation with acoustic biofeedback in patients with central scotoma looks like a useful technique for improving fixation stability, reading performance and quality of life.

Location and stability of the preferred retinal locus in native Persian-speaking patients with age-related macular degeneration

CLINICAL RELEVANCE

The findings of this study can be used in the selection of the preferred retinal locus to establish better rehabilitation services such as eccentric viewing training for patients with age-related macular degeneration.

BACKGROUND

The aim of this study was to determine the characteristics of the preferred retinal locus in native Persian-speaking patients with age-related macular degeneration.

METHODS

In this non-interventional case series, all patients with a diagnosis of age-related macular degeneration referred to the Retina Clinic of the Rassoul Akram Hospital, Tehran, Iran, were evaluated. The fixation characteristics were evaluated monocularly using the MP1 microperimeter (Nidek Technologies, Padua, Italy). Optical coherence tomography was used to determine the location of the central fovea. The images were overlaid and the preferred retinal locus-fovea distance was measured using Image J software.

RESULTS

Fifty-one eyes of 35 patients with a mean age of 73.8 ± 7.7-years were evaluated in this study. Inferior-field, left-field, central-field, right-field, and superior-field preferred retinal locus were detected in 49 per cent, 33.3 per cent, 7.8 per cent, 5.9 per cent, and 3.9 per cent of the subjects, respectively. Fixation was stable in 70.6 per cent, relatively unstable in 15.7 per cent, and unstable in 13.7 per cent of the participants. Significant differences were not found in the mean values of logMAR visual acuity between different fields of the preferred retinal locus after Bonferroni correction (p = 0.031). Analysis of co-variance showed no significant difference in mean sensitivity values between different locations of the preferred retinal locus (p = 0.07). The mean preferred retinal locus-fovea distance was not significantly different between different fields of the preferred retinal locus (p = 0.063).

CONCLUSIONS

Native Persian-speaking patients with central scotoma secondary to age-related macular degeneration place their self-selected preferred retinal locus most frequently in the inferior and left visual field, which would result in scotoma displacement to the superior and right visual field. Fixation stability was statistically similar in different locations of preferred retinal locus, but it improved with decreasing the preferred retinal locus-fovea distance.