Faran Sabeti

Multifocal pupillographic assessment of age-related macular degeneration.

Purpose. To investigate retinal function in subjects with unilateral exudative age-related macular degeneration (AMD) using multifocal pupillographic objective perimetry (mfPOP) and to assess the diagnostic accuracy of this technique. Methods. We tested each of 20 exudative AMD patients and 20 control subjects with 4 different mfPOP stimulus variants. Multifocal stimuli consisting of 24 or 44 independent stimulus regions per eye extending from fixation to 15° eccentricity were presented dichoptically. The aperiodic stimuli were presented at 1 or 4 s mean intervals. Video cameras recorded pupil responses under infrared illumination. Test duration consisted of 8 segments of 30 s. Stimuli were presented at a luminance of 250 cd/m2 and a background of 10 cd/m2. Peak regional contraction amplitudes, time to peaks, and a linear combination of these were used to produce receiver operator characteristic (ROC) curves to measure the diagnostic accuracy of this method. Results. Mean constriction amplitudes of exudative AMD subjects were decreased by 0.77 ± 0.15 dB (p < 5 × 10−7). Stimulus ensembles with 44 regions and faster presentation rates produced the largest effect on response sizes (t = 3.63; p < 0.0002). When comparing the control eyes to exudative AMD eyes, the area under the curve of ROC plots was 0.96 ± 0.03 (mean ± SE). This was achieved for asymmetry analysis of the difference in response amplitudes obtained from the two eyes at each point in the visual field. Conclusions. The mean effect of exudative AMD on contraction amplitudes reflected the severity of disease, and ROC analysis from amplitude deviations improved the sensitivity of detection of exudative AMD. A longitudinal investigation into the mfPOP responses of patients with non-exudative AMD may detect and classify visual fields with poor prognosis.

Multifocal Pupillography Identifies Ranibizumab Induced Changes In Retinal Function For Exudative Age-related Macular Degeneration

PURPOSE To investigate the efficacy of multifocal pupillographic objective perimetry (mfPOP) to quantify the effects of intravitreal ranibizumab injection for choroidal neovascularization (CNV) secondary to exudative age-related macular degeneration (AMD). METHODS mfPOP visual fields from 20 patients with unilateral exudative AMD treated with intravitreal ranibizumab were measured before and after 3 months of treatment and were compared with that in 30 normal subjects. Two stimulus types consisting of ensembles of 24 or 44 independent stimuli per eye had a mean presentation interval at each region of 1 second. Pupil responses were recorded with video cameras under infrared illumination. Multiple linear models were fitted to contraction amplitudes and delay to peak responses, to determine the independent effects of exudative AMD before and after ranibizumab therapy. RESULTS After 3 months of treatment, mean additional response delays compared to normal subjects for the 24-region stimulus improved significantly (P < 5 × 10⁻⁹) from a mean of 18.82 ± 3.0 ms at baseline to 7.45 ± 3.15 ms. The mean effect of exudative AMD at baseline decreased constriction amplitude by -1.11 ± 0.24 dB (P < 0.00001) with little improvement after ranibizumab therapy. Small pretreatment elevations of extrafoveal sensitivity correlated with improvements in central retinal thickness (CRT) after treatment (P < 0.0005). CONCLUSIONS Improvements in mfPOP contraction amplitudes and time to peak responses were measured in eyes treated with intravitreal ranibizumab; however, response delays appeared to be the most indicative of functional improvement. Confirmation of hypersensitivity in the extrafoveal field in a larger group may support this finding as a prognostic marker for good treatment outcomes.

Spatial and temporal stimulus variants for multifocal pupillography of the central visual field

Multifocal pupillographic objective perimetry (mfPOP) has the advantage of being a non-invasive, objective method for measuring up to 88 visual field responses from both eyes concurrently within 5min. To date mfPOP has been used to assess the peripheral visual field. Here we examine the practicality of mfPOP for testing the macular region of the visual field. This study examines variations in temporal presentation rate, spatial stimulus layout and luminance intensity in a group of normal subjects to determine the optimal parameters for achieving high signal to noise ratios for a macular version of mfPOP. Responses to multifocal stimuli comprising 24 or 44 stimulus regions per eye were measured dichoptically achieving median signal to noise ratios of 2.47 z-score units. Long stimulus presentation intervals combined with 24 region non-overlapping layouts produced the largest contraction amplitudes and shortest response delays.

Multifocal pupillography in early age-related macular degeneration.

Purpose To investigate the potential of multifocal pupillographic objective perimetry to assess changes in retinal function with clinical severity of age-related macular degeneration (AMD). Methods Pupil responses were recorded from 40 subjects with AMD and 23 normal control subjects (mean ± SD age, 71.3 ± 5.1 years). Age-related macular degeneration subjects were classified according to the Age-Related Eye Disease Study (AREDS) classification system and allocated into one of four AMD severity groups. Three multifocal pupillographic objective perimetry stimulus variants that were identical in luminance but varied in spatiotemporal sequence were used. In one of the three protocols, stimuli were presented with a pedestal flicker for 266 milliseconds at 15 Hz. Results On average, response amplitudes demonstrated a significant change in sensitivity with progression from early-stage (0.32 ± 0.08 dB, t = 3.88) to late-stage (−1.60 ± 0.12 dB, t = −12.7) age-related macular degeneration. Response delays followed a similar trend with the longest delays in AREDS4 (57.2 ± 1.9 milliseconds, t = 29.5). Ring analysis identified the largest mean effect on responses within the central 6 degrees of fixation. The NewStimuli protocol achieved the best diagnostic accuracy across all severity groups with area under the curve values of 0.85 ± 0.066 (AREDS1), 0.908 ± 0.085 (AREDS2), 0.929 ± 0.040 (AREDS3), and 1.0 ± 0.0 (AREDS4). Conclusions The mean effect of AMD on contraction amplitudes and response delays reflected the severity of disease, and the NewStimuli protocol achieved good diagnostic accuracy across all AMD severity groups. Multifocal pupillographic objective perimetry may potentially be a useful method in monitoring progression of AMD and assessing change in retinal function with novel interventions in early AMD. Longitudinal studies are required to identify biomarkers that predict eyes at risk of progression.

Multifocal Pupillography Identifies Changes in Visual Sensitivity According to Severity of Diabetic Retinopathy in Type 2 Diabetes.

PURPOSE Retinal light sensitivity loss has been shown to occur prior to other signs of retinopathy and may predict the sight-threatening sequelae. A rapid, objective perimetric test could augment diabetes care. We investigated the clinical use of multifocal pupillographic objective perimetry (mfPOP) to identify patients with and without diabetic retinopathy. METHODS Retinopathy severity was determined using the Early Treatment of Diabetic Retinopathy Study (ETDRS) standard for fundus photography. Pupillary responses were measured from both eyes of 25 adults with none to moderate diabetic retinopathy and 24 age-matched controls, using three mfPOP stimulus variants. Multifocal pupillographic objective perimetry stimulus variants tested 44 regions per eye arranged in a five-ring dartboard layout presented within either the central 30° or 60° of fixation. Receiver operator characteristic (ROC) curves were produced from contraction amplitudes and time to peak responses. RESULTS Regression analysis revealed that mean amplitude deviations were larger with severity of early retinopathy. On average, the longest delays were measured in patients with no retinopathy. The brightest wide-field stimuli produced the highest area under the ROC curve for differentiating eyes with no retinopathy from nonproliferative diabetic retinopathy (NPDR) and from healthy eyes (100 ± 0.0%, mean ± SE). The asymmetry in local delay deviations between eyes tended to produce higher sensitivity and specificity than amplitude deviations. CONCLUSIONS Asymmetry in local response delays measured by mfPOP may provide useful information regarding the severity of diabetic retinopathy and may have clinical use as a rapid, noninvasive method for identifying functional loss even in the absence of NPDR.

Comparing multifocal pupillographic objective perimetry (mfPOP) and multifocal visual evoked potentials (mfVEP) in retinal diseases

Multifocal pupillographic objective perimetry (mfPOP) shows regions of slight hypersensitivity away from retinal regions damaged by diabetes or age-related macular degeneration (AMD). This study examines if such results also appear in multifocal visual evoked potentials (mfVEPs) recorded on the same day in the same patients. The pupil control system receives input from the extra-striate cortex, so we also examined evidence for such input. We recruited subjects with early type 2 diabetes (T2D) with no retinopathy, and patients with unilateral exudative AMD. Population average responses of the diabetes patients, and the normal fellow eyes of AMD patients, showed multiple regions of significant hypersensitivity (p < 0.05) on both mfPOP and mfVEPs. For mfVEPs the occipital electrodes showed fewer hypersensitive regions than the surrounding electrodes. More advanced AMD showed regions of suppression becoming centrally concentrated in the exudative AMD areas. Thus, mfVEP electrodes biased towards extra-striate cortical responses (surround electrodes) appeared to show similar hypersensitive visual field locations to mfPOP in early stage diabetic and AMD damage. Our findings suggest that hypersensitive regions may be a potential biomarker for future development of AMD or non-proliferative diabetic retinopathy, and may be more informative than visual acuity which remains largely undisturbed during early disease.

Improving face identity perception in age-related macular degeneration via caricaturing

Patients with age-related macular degeneration (AMD) have difficulty recognising people’s faces. We tested whether this could be improved using caricaturing: an image enhancement procedure derived from cortical coding in a perceptual ‘face-space’. Caricaturing exaggerates the distinctive ways in which an individual’s face shape differs from the average. We tested 19 AMD-affected eyes (from 12 patients; ages 66–93 years) monocularly, selected to cover the full range of vision loss. Patients rated how different in identity people’s faces appeared when compared in pairs (e.g., two young men, both Caucasian), at four caricature strengths (0, 20, 40, 60% exaggeration). This task gives data reliable enough to analyse statistically at the individual-eye level. All 9 eyes with mild vision loss (acuity ≥ 6/18) showed significant improvement in identity discrimination (higher dissimilarity ratings) with caricaturing. The size of improvement matched that in normal-vision young adults. The caricature benefit became less stable as visual acuity further decreased, but caricaturing was still effective in half the eyes with moderate and severe vision loss (significant improvement in 5 of 10 eyes; at acuities from 6/24 to poorer than <6/360). We conclude caricaturing has the potential to help many AMD patients recognise faces.

Learning Complex Texture Discrimination

Di erent isotrigon texture types are only discriminable from random binary patterns and each other by their third and higher-order spatial correlations. Their mean contrast and spatial frequency content is identical to random noise. Our ability to make these discriminations has be proposed to be innate. We previously investigated learning of 17 isotrigon types in seven naïve subjects, where each type was tested in 14 sessions over 6 weeks. Signi cant learning was observed. Here we examined if 7 learning sessions conducted every 30 minutes on one day achieved similar learning. We also tested participants at a recall session, 2.5 months later. We used 11 naïve subjects with normal vision. We examined discrimination from random patterns of a subset of 5 of the original texture types, with 16 4AFC repeats/texture/session (5*11*8*16=7040 discriminations). Learning was similar to that achieved in the 6-week sessions. Two of the textures showed signi cant learning with mean discrimination improvement in probability of correct discrimination of 0.125 ± 0.058 to 0.244 ± 0.089 (p = 0.03 and 0.01). The textures that showed signi cant learning were the Cross-Even and Wolf-Odd type. However, both of these textures showed a reduction in learning at the nal recall session. It appears that the number of discriminations, rather than the duration of the This ite uses cooki s. By continuing to use our website, you re agreeing to o r privacy policy. | Accept 7/31/2019 Learning Complex Texture Discrimination | JOV | ARVO Journals https://jov.arvojournals.org/article.aspx?articleid=2699253&resultClick=1 2/2 learning period is the key factor in learning di erences in texture appearance based upon higher order spatial correlations. Initial performance was not chance so there appears to be some innate ability in naïve subjects. Meeting abstract presented at VSS 2018