Novel quantitative assessment of metamorphopsia in maculopathy

Quantifying the Relationship Between Unilateral Induced Metamorphopsia and Stereopsis Impairment

Purpose

To investigate the relationship between unilateral metamorphopsia, characterized by visual distortions in one eye, and impaired stereopsis.

Methods

Utilizing both near and distance measurements through advanced testing systems, including 4K smartphones and an active shutter three-dimensional system, we simulated varying degrees of unilateral metamorphopsia in 30 healthy young adults aged between 21 and 29 years. Two types of contour-based stereotest symbols, lines and squares, were developed. Distortions were classified into six distinct patterns, each further divided into eight grades of severity. Participants were tasked with identifying visual targets, and their stereothresholds were determined under different conditions of induced distortion. Stereopsis was measured within a range of 2.9 to 1.0 log arcsec, at 0.2 log arcsec intervals. Stereopsis changes under different distortion scenarios were analyzed using the generalized estimating equations, with a sequential Bonferroni adjustment applied for pairwise comparisons.

Results

A direct and quantifiable correlation was observed between the severity of metamorphopsia and reductions in stereopsis. As the degree of visual distortion increased, notably in both frequency and amplitude, there was a corresponding decline in stereopsis. This relationship held true in both near and distance measurements of stereopsis. Statistical analyses further reinforced these findings, highlighting a significant detrimental effect of distortion components on stereoacuity.

Conclusions

The findings highlight the clinical significance of understanding the interplay between unilateral metamorphopsia and stereopsis. Early interventions in conditions leading to metamorphopsia might be critical to maintaining optimal stereopsis.

The Invisibility of Scotomas I: The Carving Hypothesis

SIGNIFICANCE

Veridical depictions of scene appearance with scotomas allow better understanding of the impact of field loss and may improve the development and implementation of rehabilitation. Explanation and depiction of the invisibility of scotoma may lead to patients' understanding and thus better compliance with related treatments.

PURPOSE

Simulations of perception with scotomas guide training, patient education, and rehabilitation research. Most simulations incorrectly depict scotomas as black patches, although the scotomas and the missing contents are usually invisible to patients. We present a novel approach to capture the reported appearance of scenes with scotomas.

METHODS

We applied a content-aware image resizing algorithm to carve out the content elided under the scotomas. With video sequences, we show how and why eye movements fail to increase the visibility of the carved scotomas.

RESULTS

Numerous effects, reported by patients, emerge naturally from the scotoma carving. Carving-eliminated scotomas over natural images are barely visible, despite causing substantial distortions. Low resolution and contrast sensitivity at farther eccentricities and saccadic blur reduce the visibility of the distortions. In a walking scenario, static objects moving smoothly to the periphery disappear into and then reemerge out of peripheral scotomas, invisibly.

CONCLUSIONS

Scotoma carving provides a viable hypothetical simulation of vision with scotomas due to loss of neurons at the retinal ganglion cell level and higher. As a hypothesis, it generates predictions that lend themselves to future clinical testing. The different effects of scotomas due to loss of photoreceptors are left for follow-up work.

A novel tool for quantitative measurement of distortion in keratoconus

Background

Keratoconus is associated with thinning and anterior protrusion of the cornea resulting in the symptoms of blurry and distorted vision. The commonly used clinical vision tests such as visual acuity and contrast sensitivity may not reflect the symptoms experienced in keratoconus and there are no quantitative tools to measure visual distortion. In this study, we used a quantitative test based on vernier alignment and field matching techniques to quantify visual distortion in keratoconus and assess its relation to corneal structural changes.

Methods

A total of 50 participants (25 keratoconus and 25 visually normal) completed the experiment where they aligned supra-threshold white target circles in opposite field in reference to guidelines and circles to complete a square structure monocularly. The task was repeated five times and the global distortion index (GDI) and global uncertainty index (GUI) were calculated as the mean and standard deviation respectively of local perceived misalignment of target circles over five trials.

Results

Both GDI and GUI were higher in participants with keratoconus compared to controls (p < 0.01). Both parameters correlated with the best corrected visual acuity, maximum corneal curvature (K_max), topographical keratoconus classification (TKC) and central corneal thickness (CCT).

Conclusion

Our findings show that the quantitative measure of distortion could be a useful tool for behavioural assessment of progressive keratoconus.

Measuring image distortions arising from age-related macular degeneration: An Iterative Amsler Grid (IAG)

Metamorphopsia, perceived as distortion of a shape, is experienced in age-related macular degeneration (AMD): straight lines appear to be curved and wavy to AMD patients and some other retinal pathologies. Conventional clinical assessment largely relies on asking patients to identify irregularities in Amsler Grids - a standardized set of equally spaced vertical and horizontal lines. Perceived distortions or gaps in the grid are a sign of macular pathology. Here, we developed an iterative Amsler Grid (IAG) procedure to obtain a quantifiable map of visual deformations. Horizontal and vertical line segments representing metamorphopsia are displayed on a computer screen. Line segments appearing distorted are adjusted by participants using the computer mouse to change their orientation in several iteratively such that they appear straight. Control participants are able to reliably correct deformations that simulate metamorphopsia while maintaining fixation in the center. In a pilot experiment, we attempted to obtain deformation maps from a small number of AMD patients. Whereas some patients with extensive scotomas found this procedure challenging, others were comfortable using the IAG and generating deformation maps corresponding to their subjective reports. This procedure may potentially be used to quantify local distortions and map them reliably in patients with early AMD.

The influence of visual distortion on face recognition

A person's ability to recognise familiar faces is critical to their participation in many aspects of society. Following an acquired brain injury or retinal disease, however, faces can appear distorted, a phenomenon known as prosopometamorphopsia. Although case reports have described a variety of changes in the appearance of faces during prosopometamorphopsia, the influence of the disorder on face recognition has not been rigorously investigated. In the present report, we quantify how well healthy observers can recognise familiar faces that have been distorted using a parametric model of prosopometamorphopsia. Our results reveal that face recognition varies systematically with the parameters of visual distortion, which, importantly, interact with the size of the face in a nonlinear but highly predictable manner. Our findings demonstrate that prosopometamorphopsia can lead to a surprising range of changes in the appearance of faces. The impact of visual distortion on face recognition thus depends critically on the distance at which the face is viewed, which is likely to change across social and clinical contexts.

Foveal Displacement following Temporal Inverted Internal Limiting Membrane Technique for Full Thickness Macular Holes: 12 Months Results

Purpose: To compare conventional 360° internal limiting membrane (ILM) peeling and temporal inverted ILM flap technique with regard to postoperative foveal displacement.Methods: Patients who underwent 23 G vitrectomy with either 360° ILM peeling (Group 1) or temporal inverted ILM technique (Group 2) for idiopathic macular hole with a minimum follow up of 12 months were included. The metamorphopsia rates and distances between fovea and 3 retinal landmarks: the first retinal vascular bifurcation or crossover located superonasal and inferonasal to the fovea and ciliary vessel at the temporal margin of the disc, were compared on MultiColor SLO and near-infrared reflectance images. In addition, papillofoveal distance was measured on B-scan optical coherence tomography (OCT).Results: A total of 57 eyes were recruited (Group 1, n = 25; Group 2, n = 32). The visual acuity at month-1 was significantly higher in Group 2 than Group 1 (p = .007). A significant postoperative foveal displacement towards the disc was observed in Group 1 and Group 2 (p < .001 and p = .002 respectively). Shortening of the papillofoveal distance was greater in Group 1 than Group 2 at all postoperative visits (p < .05 for all). Furthermore, significant changes in papillofoveal distance continued until 6 months in Group 1 (p < .05 for all), whereas no significant changes occurred in Group 2 after month-1 (p > .05 for all). The complaints of metamorphopsia was significantly higher in Group 1 (n = 18/25) compared with Group 2 (n = 10/32) (p = .002).Conclusion: Temporal inverted ILM flap appear to be superior to 360° ILM peeling with regard to faster visual rehabilitation, lower rates of subjective metamorphopsia and less foveal displacement.

Test-Retest-Reliability of Computer-Based Metamorphopsia Measurement in Macular Diseases

In this study, the test-retest-reliability as one aspect of reliability of metamorphopsia measurements using a computer-based measuring method was determined in patients with macular diseases. Metamorphopsia amplitude, position, and area were quantified using AMD - A Metamorphopsia Detector software (app4eyes GmbH & Co. KG, Germany) in patients with diabetic, myopic, or uveitic macular edema, intermediate or neovascular age-associated macular degeneration, epiretinal membrane, vitelliform maculopathy, Irvine-Gass syndrome, or macular edema due to venous retinal occlusion. The intraclass correlation coefficient (ICC) was calculated in order to determine the repeatability of two repeated measurements and was used as an indicator of the reliability of the measurements. In this study, metamorphopsia measurements were conducted on 36 eyes with macular diseases. Metamorphopsia measurements made using AMD - A Metamorphopsia Detector software were highly reliable and repeatable in patients with maculopathies. The intraclass correlation coefficient of all indices was excellent (0.95 - 0.97). For diseases of the vitreoretinal interface or macular diseases with intra- or subretinal edema, this metamorphopsia measurement represents a supplement for visual function testing in the clinic, as well as in clinical studies.

Correlation between new OCT parameters and metamorphopsia in advanced stages of epiretinal membranes

PURPOSE

To correlate metamorphopsia provided by M-CHARTS and ectopic inner foveal layers (EIFL) or 'central bouquet' abnormality (CBA) in patients with advanced stages of epiretinal membrane (ERM) following the novel Optical Coherence Tomography (OCT)-based grading scheme.

METHODS

In 60 eyes of 57 patients affected by ERM (stages 3 and 4), the degree of metamorphopsia using the M-CHARTS was evaluated (M-SCORE) and correlated with EIFL, CBA and central foveal thickness (CFT) as measured on OCT scans.

RESULTS

A total of 37 and 23 eyes were diagnosed having ERM stages 3 and 4, respectively. Mean vertical and horizontal M-SCORE (M-V and M-H) were 0.64 ± 0.43 and 0.58 ± 0.37 standard deviations, respectively. Mean M-SCORE exhibited a statistically significant correlation with EIFL and CFT (both p < 0.0001), but not with CBA (p = 0.84). Analysing the direction of metamorphopsia separately, M-H and M-V were significantly correlated with EIFL (both p < 0.0001), but not with CBA thickness (p = 0.70 and 0.33 respectively). Ectopic inner foveal layers (EIFL) was significantly influenced by the presence of CBA (CBA present, 158.29 ± 63.53 micron; CBA absent, 107.05 ± 94.13 micron, p = 0.04). No significant differences were found for both M-V and M-H with respect to the presence of CBA.

CONCLUSIONS

Based on the novel OCT-based grading scheme for ERMs, our results demonstrate that EIFL, but not CBA, might be considered a good indicator for metamorphopsia in patients with advanced ERMs.

Monocular and binocular end-points after epiretinal membrane surgery and their correlation to patient-reported outcomes

PURPOSE

This study evaluates current available endpoints for epiretinal membrane (ERM) surgery and examine their correlation to patient reported outcomes (PRO).

METHODS

Retrospective study including 38 eyes of 38 patients who underwent cataract extraction and subsequent vitrectomy for idiopathic ERM. The fellow eye was phakic with good visual acuity. The registered outcomes were monocular and binocular visual acuity, stereoacuity, M-chart metamorphopsia score, aniseikonia and aniseikonia tolerance range (ATR). Two questionnaires were completed: the convergence insufficiency symptom survey and Visual Function Questionnaire (VFQ-39).

RESULTS

Median total aniseikonia was 11% (range 0-35). There was a statistically significant correlation between the mean total M-chart score of the study eye and VFQ-Near (Spearman rho: VFQ-Near: -0.54, p < 0.01). There was no correlation between the best corrected visual acuity (BCVA) of the project eye, binocular BCVA, stereoacuity, ATR or mean total aniseikonia and PRO (Spearman p-values > 0.05). There was no correlation between mean total aniseikonia and mean total M-chart score (Spearman rho: 0.21 p = 0.26). There was a large variation between the mean total M-chart scores and questionnaire results.

CONCLUSION

The mean total M-chart score is currently the best end-points to predict PRO of ERM surgery; however, it is possible to have high M-chart values and have no visual complaints.

The tolerance of anisometropia

PURPOSE

This study examines aniseikonia, Aniseikonia tolerance range (ATR), anisometropia and patient-reported outcomes (PRO) in an anisometropic population compared with a non-anisometropic population. The relationship between anisometropia and aniseikonia is determined, and the correlations between aniseikonia, anisometropia and ATR versus PRO are described.

METHODS

One hundred and twenty-three patients with IOL-induced anisometropia ≥1 dioptre (D) (the anisometropic group) and 17 patients who had IOL-induced anisometropia <1 D (the control group) were included. Best corrected visual acuity, aniseikonia, ATR and stereoacuity were examined, and two questionnaires were completed: convergence insufficiency symptom survey (CISS) and Visual Function Questionnaire (VFQ-39).

RESULTS

One hundred and thirteen patients had anisometropia >1 and <3 D, and 10 patients had anisometropia >3 D. There was no difference in PRO between the control group and the anisometropic group (Mann-Whitney, p-values VFQ: 0.96, CISS: 0.06). There was no correlation between anisometropia and PRO (Spearman's rank correlation test p-values: VFQ: 0.54, CISS: 0.57). Patients with low ATR were more sensitive towards anisometropia and had lower PRO than patients with high ATR (Mann-Whitney, p-values: VFQ: 0.0008, CISS: 0.11). A large tolerance of aniseikonia was observed.

CONCLUSION

No correlation between PRO and anisometropia or aniseikonia was found. Patients with low ATR are at risk of visual complaints if they are exposed to IOL-induced anisometropia. ATR might be a future screening tool in cataract patients.

Digital Nullification of Visual Distortion to Quantify Metamorphopsia: A Pilot Study

BACKGROUND AND OBJECTIVE

To evaluate a novel digital method of metamorphopsia quantification in patients with symptomatic visual distortion as determined by M-CHARTS.

PATIENTS AND METHODS

In this institutional review board-approved, prospective, cross-sectional observational study, subjects were presented with an objectively straight dotted line that bisects a central fixation point. The subjects digitally altered the line's contour until it appeared straight. Calculation of the area between the original objectively straight line presented to the subject and their newly manipulated line was performed to determine the manipulated area under the curve (M-AUC).

RESULTS

Sixty-two percent of test targets were fully or significantly straightened by affected subjects. M-AUC was significantly correlated with M-CHARTS scores in both the horizontal (P < .001) and vertical (P = .05) orientations.

CONCLUSIONS

The deformation of an objectively straight line by a subject with metamorphopsia may be a viable way of both quantifying and spatially characterizing visual distortions. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:11-20.].

Recent Advances of Computerized Graphical Methods for the Detection and Progress Assessment of Visual Distortion Caused by Macular Disorders

Recent advances of computerized graphical methods have received significant attention for detection and home monitoring of various visual distortions caused by macular disorders such as macular edema, central serous chorioretinopathy, and age-related macular degeneration. After a brief review of macular disorders and their conventional diagnostic methods, this paper reviews such graphical interface methods including computerized Amsler Grid, Preferential Hyperacuity Perimeter, and Three-dimensional Computer-automated Threshold Amsler Grid. Thereafter, the challenges of these computerized methods for accurate and rapid detection of macular disorders are discussed. The early detection and progress assessment of macular disorders can significantly enhance the required clinical procedure for the diagnosis and treatment of macular disorders.

Idiopathic Macular Hole: A Comprehensive Review of Its Pathogenesis and of Advanced Studies on Metamorphopsia

Vitreous anteroposterior traction is an important factor that affects macular hole (MH) formation at the early stage, and vitreous tangential traction can lead to further hole expansion after hole formation. Recent studies have highlighted the significance of Müller cells for the pathogenesis of MH. Since the advent of MH treatment, success rates for MH closure have significantly improved, as has postoperative visual acuity. However, metamorphopsia, an initial and common symptom of MH, still exists. Metamorphopsia is significantly related to the deterioration of visual quality of life and can be used as an independent index to evaluate visual function before and after surgery. In MH patients, metamorphopsia has different manifestations representing different clinical implications. M-CHARTS, as a new means of inspection, can quantify the degrees of metamorphopsia, and with the development of optical coherence tomography (OCT), layer-by-layer scanning of the retinal structure has become possible. These methods enable detailed analysis of the connections between the degree of metamorphopsia and relevant OCT parameters. Preoperative OCT parameters can be used to evaluate the prognosis of the postoperative visual function of MH patients and are therefore of great significance in guiding the treatment of MH patients.

Persistent metamorphopsia associated with branch retinal vein occlusion

Purpose

To investigate longitudinal changes in metamorphopsia associated with branch retinal vein occlusion.

Methods

In this prospective observational case series, we included 32 eyes (32 patients) with branch retinal vein occlusion and acute macular edema. Eyes were treated as needed with intravitreal ranibizumab injections for 12 months. At baseline and 1, 6, and 12 months after initiating treatment, metamorphopsia was quantified using M-CHARTS. Retinal morphology was examined through optical coherence tomography.

Results

Logarithm of the minimum angle of resolution visual acuity progressively improved from 0.342 ± 0.304 (Snellen equivalent: 20/44) at baseline to 0.199 ± 0.259 (20/32) and 0.118 ± 0.195 (20/26) at 1 and 12 months, respectively (both P < 0.001). The M-CHARTS score significantly decreased from 0.63 ± 0.61 at baseline to 0.45 ± 0.50 at 1 month (P = 0.044), but no further improvement was achieved with 1 year of additional treatment (6 months: 0.47 ± 0.53 [P = 0.094] and 12 months: 0.50 ± 0.44 [P = 0.173]). Three (13.6%) of 22 eyes with baseline metamorphopsia had complete metamorphopsia resolution. At 12 months, the M-CHARTS score was correlated with baseline foveal thickness (r = 0.373, P = 0.035) and the baseline M-CHARTS score (r = 0.503, P = 0.003). A multiple regression analysis revealed that only the baseline M-CHARTS score was correlated with the 12-month M-CHARTS score (β = 0.460, P = 0.027).

Conclusions

Eyes with branch retinal vein occlusion often have persistent metamorphopsia, even when visual acuity and retinal morphology improve. Metamorphopsia at 12 months was correlated with metamorphopsia and foveal thickness at baseline.

Metamorphopsia and vision-related quality of life among patients with age-related macular degeneration

OBJECTIVE

To assess subjective and quantified metamorphopsia, as well as vision-related quality of life (QOL), in patients with age-related macular degeneration (AMD) to determine whether there is a correlation between quantified metamorphopsia and vision-related QOL in patients with AMD.

METHODS

A cross-sectional study of patients with AMD. Patients who had a best-corrected visual acuity less than 20/200, vitreomacular adhesion, vitreomacular traction, epiretinal membrane, macular hole, macular edema by causes other than AMD, diabetic retinopathy, retinal detachment, previous retinal surgery, glaucoma, amblyopia, or strabismus were excluded. Subjective perceptions of metamorphopsia were captured by a validated 10-item questionnaire. M-CHARTS (Inami, Japan) was used to detect quantified metamorphopsia. Quantified metamorphopsia was scored horizontally and vertically. The mean values of 3 repeated examinations were used for data analysis. The 25-item National Eye Institute Visual Functioning Questionnaire (VFQ-25) was used to assess vision-related QOL.

RESULTS

Among 102 eyes with AMD, the most commonly reported subjective perception of metamorphopsia included lines of words on books, newspapers, or computer displays (45.1%), followed by frames of windows or bookshelves (22.6%), lines of tiles on bathroom wall (21.6%), and people's faces (18.6%). Eyes with wet AMD had significantly higher horizontal and vertical metamorphopsia scores compared with eyes with dry AMD (p < 0.0001). The higher horizontal metamorphopsia score and the higher vertical metamorphopsia score between the 2 eyes were both negatively correlated with the NEI VFQ-25 composite score (Spearman rank correlation r = -0.3207, p = 0.0010; Spearman rank correlation r = -0.3190, p = 0.0011).

CONCLUSIONS

In our study, the most common subjective metamorphopsia was distortion of lines of words on books, newspapers, or computer displays. Compared to eyes with dry AMD, those with wet AMD had higher quantified horizontal and vertical metamorphopsia. Between the 2 eyes, both the higher horizontal and vertical metamorphopsia scores were correlated with the NEI VFQ-25 composite score.

Functional changes at the preferred retinal locus in subjects with bilateral central vision loss

PURPOSE

Subjects with bilateral central vision loss (CVL) use a retinal region called the preferred retinal locus (PRL) for performing various visual tasks. We probed the fixation PRL in individuals with bilateral macular disease, including age-related macular degeneration (AMD) and Stargardt disease (STGD), for localized sensitivity deficits.

METHODS

Three letter words at the critical print size were presented in the NIDEK MP-1 microperimeter to determine the fixation PRL and its radial retinal eccentricity from the residual fovea in 29 subjects with bilateral CVL. Fixation stability was defined as the median bivariate contour ellipse area (BCEA) from 3 fixation assessments. A standard 10-2 grid (68 locations, 2° apart) was used to determine central retinal sensitivity for Goldmann size II test spots. Baseline and follow-up supra-threshold screening of the fixation PRL for localized sensitivity deficits was performed using high density (0.2° or 0.3° apart) 0 dB Goldmann size II test spots. Custom MATLAB code and a dual bootstrapping algorithm were used to register test-spot locations from the baseline and follow-up tests. Locations where the 0 dB test spots were not seen on either test were labeled as micro-scotomas (MSs).

RESULTS

Median BCEA correlated poorly with the radial eccentricity of the fixation PRL. Mean (±SD) sensitivity around the PRL from 10-2 testing was 4.93 ± 4.73 dB. The average percentage of MSs was similar for patients with AMD (25.4%), STGD (20.3%), and other etiologies of CVL (27.1%).

CONCLUSIONS

The fixation PRL in subjects with bilateral CVL frequently includes local regions of sensitivity loss.

How to Build a Dichoptic Presentation System That Includes an Eye Tracker

The presentation of different stimuli to the two eyes, dichoptic presentation, is essential for studies involving 3D vision and interocular suppression. There is a growing literature on the unique experimental value of pupillary and oculomotor measures, especially for research on interocular suppression. Although obtaining eye-tracking measures would thus benefit studies that use dichoptic presentation, the hardware essential for dichoptic presentation (e.g. mirrors) often interferes with high-quality eye tracking, especially when using a video-based eye tracker. We recently described an experimental setup that combines a standard dichoptic presentation system with an infrared eye tracker by using infrared-transparent mirrors1. The setup is compatible with standard monitors and eye trackers, easy to implement, and affordable (on the order of US$1,000). Relative to existing methods it has the benefits of not requiring special equipment and posing few limits on the nature and quality of the visual stimulus. Here we provide a visual guide to the construction and use of our setup.

Metamorphopsia Associated with Branch Retinal Vein Occlusion

PURPOSE

To apply M-CHARTS for quantitative measurements of metamorphopsia in eyes with acute branch retinal vein occlusion (BRVO) and to elucidate the pathomorphology that causes metamorphopsia.

METHODS

This prospective study consisted of 42 consecutive patients (42 eyes) with acute BRVO. Both at baseline and one month after treatment with ranibizumab, metamorphopsia was measured with M-CHARTS, and the retinal morphological changes were examined with optical coherence tomography.

RESULTS

At baseline, metamorphopsia was detected in the vertical and/or horizontal directions in 29 (69.0%) eyes; the mean vertical and horizontal scores were 0.59 ± 0.57 and 0.52 ± 0.67, respectively. The maximum inner retinal thickness showed no association with the M-CHARTS score, but the M-CHARTS score was correlated with the total foveal thickness (r = 0.43, p = 0.004), the height of serous retinal detachment (r = 0.31, p = 0.047), and the maximum outer retinal thickness (r = 0.36, p = 0.020). One month after treatment, both the inner and outer retinal thickness substantially decreased. However, metamorphopsia persisted in 26 (89.7%) of 29 eyes. The posttreatment M-CHARTS score was not correlated with any posttreatment morphological parameters. However, the posttreatment M-CHARTS score was weakly correlated with the baseline total foveal thickness (r = 0.35. p = 0.024) and closely correlated with the baseline M-CHARTS score (r = 0.78, p < 0.001).

CONCLUSIONS

Metamorphopsia associated with acute BRVO was quantified using M-CHARTS. Initial microstructural changes in the outer retina from acute BRVO may primarily account for the metamorphopsia.

Quantifying Visual Dysfunction and the Response to Surgery in Macular Pucker

PURPOSE

To measure the effects of macular pucker (MP) on macular structure and quantify function by measuring visual acuity (VA), contrast sensitivity (CS), and distortions. The effects of surgery were quantitatively evaluated using these measures.

DESIGN

Prospective, comparative case series.

PARTICIPANTS

Fifty-three patients with unilateral MP and normal fellow eyes: 24 operated MP subjects, 17 unoperated controls, and 12 reproducibility subjects.

METHODS

Posterior vitreous detachment was diagnosed by ultrasound and ellipsoid zone disruption (EZD) was determined by OCT, which also measured macular thickness and volume. Vision was assessed, by measuring VA (logMAR) and CS (Freiburg acuity contrast testing: Weber index, %W). A visual distortions index (%DI) was calculated using 3-dimensional threshold Amsler grid testing. Comparisons to controls were performed before surgery and at 1, 3, 6, and 12 months after vitrectomy/membrane peel without chromodissection.

MAIN OUTCOME MEASURES

Posterior vitreous detachment (ultrasound), EZD (OCT), macular thickness and volume (OCT), VA (logMAR), CS (%W), distortions (%DI).

RESULTS

Posterior vitreous detachment was present in 90% of MP eyes, but only 50% of fellow eyes (P < 0.001). All structural and functional indices were worse (28% to 5-fold) in the 24 operated MP eyes than the 17 unoperated MP eyes (P < 0.001). Before surgery, EZD was present in 33% of operated MP eyes but none of the unoperated MP eyes (P < 0.02). The macula was thicker (514±85 μm vs. 257±59 μm; P < 0.001) with greater volume (3.22±0.56 μl vs. 2.14±0.22 μl; P < 0.001) in operated MP eyes than normal fellow eyes. Before surgery, MP eyes had VA = 0.53 logMAR (Snellen equivalent, 20/67) vs. controls = 0.21 (20/32); P < 0.001; CS was 8.61±5.36 %W vs. controls = 3.71±1.47 %W (P < 0.001); and distortions were 7.61±12.6 %DI vs. controls = 0.13±0.61 %DI (P < 0.001). EZD was associated with worse VA (P < 0.01) and CS (P < 0.03) before and after surgery. Each outcome measure improved progressively at 1, 3, 6, and 12 months after surgery, but only %DI and macular volume normalized.

CONCLUSIONS

These quantitative measures characterize the impact of MP on macular structure and function. All indices improved after surgery, but only distortions and macular volume normalized. Contrast sensitivity measurements and quantification of distortions can objectively assess visual dysfunction in MP and may be useful outcome measures of therapy.