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.

Changes in Metamorphopsia in Patients Undergoing Treatment for Vitreoretinal Disorders

PURPOSE

To quantify and compare the severity of metamorphopsia in patients undergoing vitrectomy for vitreoretinal disorders.

METHODS

Data were collected evaluated from 319 patients with vitreoretinal disorders, including epiretinal membrane (ERM), macular hole (MH), cystoid macular edema with branch retinal vein occlusion (BRVO-CME), CME with central retinal vein occlusion (CRVO), diabetic macular edema (DME), macula-off rhegmatogenous retinal detachment (M-off RD), and macula-on RD (M-on RD). Metamorphopsia was recorded with the M-CHARTS preoperatively and at 3 and 6 months postoperatively.

RESULTS

Preoperative and 6-month postoperative metamorphopsia scores were 0.69 ± 0.50 and 0.50 ± 0.52, respectively. Before surgery, 94% of patients presented with metamorphopsia (score ≥0.2). Preoperative metamorphopsia scores were significantly correlated with postoperative metamorphopsia scores (r = 0.378, p < 0.0001). Preoperative metamorphopsia score was significantly higher for ERM (0.89) than for DME (0.51). Vitrectomy significantly improved metamorphopsia in ERM and MH but not in the other disorders. In contrast, treatment improved visual acuity for all disorders except CRVO-CME and M-on RD.

CONCLUSION

This quantitative study indicated that metamorphopsia is present in most patients undergoing surgery for vitreoretinal diseases and is most severe in ERM. In these patients, vitrectomy improved visual acuity but not metamorphopsia.

Incidence of Metamorphopsia After Successful Rhegmatogenous Retinal Detachment Surgery: A Systematic Review and Meta-Analysis

PURPOSES

To investigate the incidence and factors influencing the occurrence of metamorphopsia in patients with simple rhegmatogenous retinal detachment (RRD) after surgery.

METHODS

Relevant studies of metamorphopsia were identified by searching in PubMed, Embase, and Cochrane until August 2022. Meta-analysis of the incidence of metamorphopsia after rhegmatogenous retinal detachment surgery was performed using Review Manager 5.4 statistical software.

RESULTS

A total of 12 studies reported 1133 participants with 469 patients with postoperative metamorphopsia. The meta-analysis showed a higher incidence of metamorphopsia in macular-off cases compared with macular-on RRD (RR = 2.88, 95% CI: 2.35 to 3.52). The use of perfluorocarbon liquid (PFCL) during pars plana vitrectomy (PPV) reduced the incidence of metamorphopsia (RR = 0.61, 95% CI: 0.41 to 0.92). There was no evidence of any important difference in metamorphopsia between participants in the PPV group and the scleral buckling (SB) group (RR = 1.04, 95% CI: 0.82 to 1.33). There was little or no difference in metamorphopsia between gas and silicon oil (SO) in the PPV group (RR = 0.89, 95% CI: 0.69 to 1.13).

CONCLUSION

The incidence of postoperative metamorphopsia is higher in macular-off RRD, and PFCL should be a preferred choice to prevent postoperative metamorphopsia in macula-off RRD cases.

Two Cases of Alice in Wonderland Syndrome with a Right Occipital Lobe Lesion Caused by Isolated Cortical Venous Thrombosis

Alice in Wonderland syndrome (AIWS) is extremely rare, occurring more often in young individuals than in older adults. Symptoms of this syndrome typically include an altered body image, size perception, and time perception. However, the pathophysiology and lesions responsible for this syndrome remain unclear. In most cases, specific lesions cannot be identified using computed tomography or magnetic resonance imaging. Two patients with isolated cortical venous thrombosis in the right occipital area experienced transient visual symptoms of AIWS. Furthermore, a literature search indicated that AIWS with visual distortions is associated with right occipital lobe lesions, supporting the findings of our study.

Correlation between Anatomical and Functional Outcomes in Patients with Idiopathic Epiretinal Membrane after Vitrectomy

BACKGROUND

Idiopathic epiretinal membrane (iERM) is a common disorder of the vitreomacular interface characterized by decreased visual acuity and metamorphopsia. This study aimed to analyze the association between the anatomical change of the retina and functional outcomes in iERM patients so as to derive the prognostic factors of visual acuity (VA) and metamorphopsia.

METHODS

Forty-five patients (one eye per patient; 45 eyes in total) who underwent pars plana vitrectomy and membrane peeling for iERM by a single surgeon were enrolled in this retrospective study. The results on best-corrected visual acuity (BCVA) and metamorphopsia as well as retinal images were obtained before the surgery and 1, 3, 6 months after the surgery. The BCVA and retinal microstructure, including central retinal thickness (CRT), ganglion cell layer (GCL) thickness, inner nuclear layer (INL) and outer nuclear layer + outer plexiform layer (ONL+OPL), and continuity of photoreceptor inner/outer segment (IS/OS) junction before and after iERM surgery were compared using paired samples t-test (continuous variables) or Chi-square test (categorical variables). Multiple regression analysis was carried out to explore the association among BCVA, M-score, and the parameters derived from optical coherence tomography.

RESULTS

Compared with preoperative data, a significant improvement in BCVA was observed 1, 3, and 6 months postoperatively (t = 5.37, p < 0.0001; t = 7.29, p < 0.0001; t = 6.44, p < 0.0001 for 1, 3, and 6 months postoperatively, respectively), whereas the M-score only decreased significantly 3 and 6 months after the surgery (t = 2.36, p = 0.02; t = 5.00, p < 0.0001, respectively). In comparison with the baseline, the CRT, INL, and ONL+OPL thickness showed a significant decrease at each postoperative follow-up time, and GCL thickness (t = 3.86, p = 0.0002) and IS/OS disruption ratio (χ2 = 4.86, p = 0.027) were markedly reduced only 6 months postoperatively. Six-month postoperative BCVA was considerably associated with preoperative CRT and ONL+OPL thickness, as well as postoperative CRT, ONL+OPL thickness, and severity of IS/OS disruption. Moreover, the M-score after surgery was markedly correlated with both the preoperative and postoperative INL and CRT thickness.

CONCLUSIONS

Both VA and M-score in iERM patients were significantly improved after vitrectomy. Pre- and post-operative CRT was significantly associated with both postoperative BCVA and M-score. Besides, pre- and post-operative INL thickness was correlated to postoperative metamorphopsia, and postoperative BCVA was associated with postoperative ONL+OPL thickness and IS/OS integrity.

Retinal displacement following repair of rhegmatogenous retinal detachment

Retinal displacement following the repair of rhegmatogenous retinal detachment (RRD) has been reported in recent studies. It was described as vertical movement of the retinal relative to its original location, as evidenced by retinal vessel printing on fundus autofluorescence imaging. This review reports the current literature on retinal displacement. We conducted an English literature search using Medline, PubMed, Embase, and Web of Science. We have reviewed 22 articles describing the diagnosis, frequency, and possible risk factors for retinal displacement. The reported rate of retinal displacement ranged from 6.4% to 62.8%, and the possible risk factors included the detachment-to-repair time, location and extent of RRD, macula-off RD, presence of subretinal fluid, use of perfluorocarbon, use of tamponade, postoperative facedown positioning, type of RRD repair, and presence of proliferative vitreoretinopathy, especially high grade. This review increases awareness of retinal displacement and its associated visual effects.

Vision-Related Parameters Affecting Stereopsis after Retinal Detachment Surgery

Even after successful surgery, the stereopsis of retinal detachment (RD) patients is inferior to that of normal subjects. However, it is unclear which visual dysfunction in the affected eye is responsible for the postoperative stereopsis impairment. This study included 127 patients after successful surgery for unilateral RD. Stereopsis, best-corrected visual acuity (BCVA), severity of metamorphopsia, letter contrast sensitivity and amount of aniseikonia were examined at 6-month postoperatively. Stereopsis was assessed using the Titmus Stereo Test (TST) and TNO stereotest (TNO). Postoperative stereopsis (log) in patients with RD were 2.09 ± 0.46 in the TST and 2.56 ± 0.62 in the TNO. Multivariate analysis with stepwise regression revealed postoperative TST was associated with BCVA, and TNO was associated with BCVA, letter contrast sensitivity, metamorphopsia and absolute values of aniseikonia. In a subgroup analysis that selected those with more impaired stereopsis, postoperative TST was associated with BCVA (p < 0.001), and TNO was associated with letter contrast sensitivity (p < 0.005) and absolute values of aniseikonia (p < 0.05) by multivariate analysis. Deterioration of stereopsis after RD surgery was affected by a variety of visual dysfunctions. The TST was affected by visual acuity, while the TNO was affected by contrast sensitivity and aniseikonia.

Prospective Study Comparing Quantitative Self-Monitoring Metamorphopsia Measurement Tools in Myopic Choroidal Neovascularization (mCNV)

Purpose

To assess the ability of two self-monitoring digital devices to detect metamorphopsia in myopic choroidal neovascularization (mCNV) and compare their usability.

Patients and Methods

This was a 12-month prospective observational study at a tertiary care eye hospital, Switzerland. Twenty-three Caucasian patients with mCNV were recruited, 21 eyes were analyzed. Primary and secondary outcome measures: Primary outcome measures were the metamorphopsia index scores as assessed by the two self-monitoring digital devices (Alleye App and AMD - A-Metamorphopsia-Detector software) at baseline, at 6 and 12 months and individual optional visits in between. Secondary outcome measures included best corrected visual acuity and morphological parameters (including disease activity) as evaluated by spectral-domain optical coherence tomography and fundus autofluorescence imaging. Location of mCNV was graded using the Early Treatment of Diabetic Retinopathy Study grid overlay. A usability questionnaire was administered at 12 months. Bland-Altman plots evaluated the limits of agreement of both devices. Linear regression analysis assessed the correlation between the difference and the average of the two scores.

Results

A total of 202 tests were performed. Disease activity of mCNV was observed at least once in 14 eyes. Both scores concordantly detected metamorphopsia exhibiting a displaced scale of measurement yielding a coefficient of determination of 0.99. Concordance rate for pathological scores was 73.3%. Both scores were not significantly different in active and inactive mCNV. Overall, the usability scores were higher for the Alleye App than the AMD - A-Metamorphopsia-Detector software (4.61±0.56 vs 3.31±1.20; p<0.001). In subjects aged >75 years, scores were slightly lower (4.08±0.86 vs 2.97±1.16; p= 0.032).

Conclusion

Whilst both self-monitoring devices concordantly identified metamorphopsia, they might act as an adjunct to hospital visits, but due to slight reactivations in mCNV and presence of metamorphopsia also in inactive disease the ability of detecting early mCNV activity might be limited.

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.

Ectopic inner foveal layer as a factor associated with metamorphopsia after vitrectomy for epiretinal membrane

PURPOSE

To analyse the relationship between the extent of metamorphopsia and optical coherence tomography (OCT) parameters including the ectopic inner foveal layer (EIFL) in patients with epiretinal membrane (ERM) who underwent pars plana vitrectomy (PPV).

METHODS

This study included 63 eyes of 62 patients who underwent PPV for ERM. Metamorphopsia was assessed by measuring the metamorphopsia score for vertical lines (MV) and metamorphopsia score for horizontal lines (MH) using M-CHARTS. Central retinal thickness (CRT), EIFL thickness and disruption of outer retinal layers were measured before and after surgery, and the relationship of these parameters with metamorphopsia scores at 3 months after vitrectomy was analysed.

RESULTS

Preoperative MV correlated with preoperative CRT and EIFL (p = 0.005 and 0.045 respectively). Postoperative MH correlated with preoperative CRT (p = 0.048), while postoperative MV correlated with preoperative CRT and EIFL (p = 0.002 and 0.0006 respectively). Postoperative MH correlated with postoperative CRT and EIFL (p = 0.001 and 0.002 respectively), and postoperative MV also correlated with postoperative CRT and EIFL (p = 0.0008 and < 0.0001 respectively). MH and MV did not correlate with outer retinal layer disruptions, both before and after vitrectomy. When multiple regression analysis was performed on preoperative and postoperative OCT parameters that correlated with postoperative metamorphopsia scores, only postoperative EIFL was identified as an independent factor associated with postoperative MV (p = 0.042).

CONCLUSION

When PPV was conducted for ERM, postoperative EIFL was found to be a significant factor associated with postoperative metamorphopsia score.

Multimodal imaging of eyes with metamorphopsia after vitrectomy for rhegmatogenous retinal detachment

Purpose:

To assess the retinal features in eyes with postoperative metamorphopsia (POM) following rhegmatogenous retinal detachment (RRD) repair using multimodal imaging (MMI).

Methods:

In this cross-sectional; case-control study, patients after successful RRD repair following 25-gauge vitrectomy, clear vitreous cavity, and corrected distance visual acuity (CDVA)>20/200 were categorized using Amsler chart: cases with POM and controls without POM. MMI was performed on swept-source platform (Triton, Topcon Inc) and the confocal scanning laser ophthalmoscope system (Spectralis HRA, Heidelberg). The measures assessed were CDVA, morphological features on optical coherence tomography, autofluorescence, and multicolor imaging (MCI).

Results:

Thirty-nine eyes were included in each group. Cases had greater number of eyes with total RRD (P = 0.029) preoperatively; abnormal foveal contour (P = 0.036), ellipsoid zone (EZ) disruption (P < 0.001) and poorer postoperative CDVA (P = 0.046) as compared to controls. Outer retinal folds and retinal shift (unintentional translocation of retina after reattachment surgery for RRD) did not differ significantly between the groups (P = 0.48 and 0.35, respectively). On MCI, the distribution of detected ERM was similar between the groups (P = 0.25). Postoperative CDVA was significantly worse in eyes with POM.

Conclusion:

POM is affected by extent of RRD, postoperative foveal contour, and EZ status but not by retinal shift.

Beyond the Visual Acuity: Assessing the Visual Function in mCNV Patients After Anti-VEGF Treatment

Purpose: To investigate visual function and vision-related quality of life (VR-QoL) changes in patients with myopic choroidal neovascularization (mCNV) after ranibizumab treatment.

Methods: Quantitatively evaluate the objective tests of visual function (visual acuity, microperimetry, and metamorphopsia by m-Charts) before and after 3+prn (pro re neta) ranibizumab treatment for 1 year. The National Eye Institute 25-Item Visual Function Questionnaire (VFQ-25) was performed to evaluate the VR-QoL.

Results: A total of 57 eyes of 57 patients were included in this study. The median average metamorphopsia score was 0.65 before treatment and improved to 0.45 after treatment (p = 0.0003). There was also a significant difference in the average threshold, macular integrity, and proportion of patients with stable fixation by the microperimetry (p < 0.000, p < 0.0001, and p = 0.03, respectively). After treatment, the VR-QoL composite, general vision subscale, and vision-related mental health subscale score were increased with borderline or statistical significance (p = 0.088, p = 0.0038, and p = 0.012, respectively). Subgroup analysis demonstrated parallel improvement of the VR-QoL score, metamorphopsia, average macular threshold, and fixation stability in patients with or without visual acuity increase. By multiple linear regression analysis, the VFQ-25 score after anti-VEGF treatment was only associated with the baseline VFQ-25 score and macular integrity. Improvements in the VFQ-25 score were only associated with changes in the metamorphopsia score.

Conclusions: Integral lifting in several aspects of visual function was observed in mCNV after ranibizumab treatment. Macular integrity and metamorphopsia, but not visual acuity, were associated with VR-QoL.

On Perception and Consciousness in HPPD: A Systematic Review

Hallucinogen-persisting perception disorder (HPPD) features as a diagnostic category in the DSM-5, ICD-11, and other major classifications, but our knowledge of the phenomenology of the perceptual symptoms involved and the changes in consciousness during the characteristic “flashbacks” is limited. We systematically evaluated original case reports and case series on HPPD to define its phenomenology, associated (psycho)pathology, and course. Our search of PubMed and Embase yielded 66 relevant publications that described 97 people who, together, experienced 64 unique symptoms of HPPD. Of these, 76% concerned symptoms characteristic of Alice in Wonderland syndrome, over 50% non-visual symptoms, and 38% perceptual symptoms not clearly linked to prior intoxication states. This is in contrast with the DSM-5 diagnostic criteria for HPPD. Even though less than half of the patients showed a protracted disease course of over a year, a third achieved remission. However, in patients with co-occurring depression (with or without anxiety) HPPD symptoms persisted longer and treatment outcomes were more often negative. Thus, unlike the acute stages of psychedelic drug intoxication, which may be accompanied by altered states of consciousness, HPPD is rather characterized by changes in the content of consciousness and an attentional shift from exogenous to endogenous phenomena. Since HPPD is a more encompassing nosological entity than suggested in the DSM-5, we recommend expanding its diagnostic criteria. In addition, we make recommendations for clinical practice and future research.

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.

Clinical Update on Metamorphopsia: Epidemiology, Diagnosis and Imaging

Purpose: To discuss the pathophysiology of metamorphopsia, its characterisation using retinal imaging and methods of assessment of patient symptoms and visual function.Methods: A literature search of electronic databases was performedResults: Metamorphopsia has commonly been associated with vitreomacular interface disorders (such as epiretinal membrane) and has also regularly been noted in diseases of the retina and choroid, particularly age-related macular degeneration and central serous chorioretinopathy. Developments in optical coherence tomography retinal imaging have enabled improved imaging of the foveal microstructure and have led to the localisation of the pathophysiology of metamorphopsia within the retinal layers of the macula. Alteration of alignment of inner and outer retinal layers at various retinal loci has been identified using multimodal imaging in patients with metamorphopsia in a range of conditions. Although the Amsler Grid assessment of metamorphopsia is a useful clinical indicator, new emerging methods of metamorphopsia assessment with psychophysical tests such as M-CHARTS and preferential hyperacuity perimetry, have been developed.Conclusions: It appears that there is a complex relationship between visual acuity and metamorphopsia symptoms that vary between retinal conditions. Although metamorphopsia has traditionally been challenging to measure in the clinic, advances in technology promise more robust, easy-to-use tests. It is possible that home assessment of metamorphopsia, particularly in conditions such as age-related macular degeneration, may help to guide the need for further clinic evaluation and consideration of treatment.

SQUARE GRID DEFORMATION ANALYSIS OF THE MACULA AND POSTOPERATIVE METAMORPHOPSIA AFTER MACULAR HOLE SURGERY

PURPOSE

To investigate the correlation between postoperative metamorphopsia and macular deformation after macular hole surgery.

METHODS

This study included 28 eyes of 28 patients who underwent vitrectomy and internal limiting membrane removal for an idiopathic macular hole. The retinal vasculatures were compared between preoperative and postoperative photographs, and postoperative deformation of the macula was assessed as deformation of the square grid. The displacement of each node was measured, and deformation of the grid was calculated as differences in the coordinates of the adjacent nodes. These parameters were analyzed to find correlation with metamorphopsia measured using the M-charts after 6 postoperative months.

RESULTS

The average deformations in the vertical and horizontal lines of the grid were 94.29 μm and 49.72 μm, respectively. Perifoveal deformation was significantly greater than parafoveal deformation (P = 0.001∼0.019). The multiple regression analysis demonstrated that the vertical M-score correlated with superior perifoveal deformation of the vertical line on the fovea (P = 0.036), and the horizontal M-score correlated with temporal perifoveal deformation of the horizontal line on the fovea (P = 0.032).

CONCLUSION

The parafoveal tissue was displaced with the fovea concurrently after internal limiting membrane removal in macular hole surgery causing perifoveal deformation, which correlated with postoperative metamorphopsia.

Measurement of drusen and their correlation with visual symptoms in patients affected by age-related macular degeneration

Age-related macular degeneration (AMD) is a common retinal disorder, which became more and more prevalent in the last decades. AMD is now the most prevalent cause of blindness in the western world. The disorder is classified into two phenotypes named dry and wet AMD. This is based on the recruitment of novel blood vessels and inflammatory exudates in wet AMD. In both phenotypes, the pathological hallmark is the presence of proteinaceous aggregates called drusen, which mostly accumulate between the choroid and the retinal pigment. Drusen in dry AMD represent the evident pathological finding although they are present, though less defined, in wet AMD. In AMD drusen are supposed to be a pathogenic trigger of the disorder. In fact, drusen may mechanically alter retinal function. A novel hypothesis exists, suggesting that a metabolic defect (systemic or focal within the retinal pigment epithelium) may be the real determinant of visual impairment, while causing the concomitant accumulation of proteinaceous debris and lipids forming the drusen. Here we face such an issue by analyzing the retinal anatomy to correlate visual impairment with the occurrence of drusen number, size and the extent of a drusenoid area in the foveal region. A comparison is made with wet AMD where new vessels and retinal exudates prevail. The study is carried out in 120 patients affected by dry or wet AMD and 21 patients where paradoxical findings are described. The main question consists in inferring whether the occurrence of visual impairment is due, in fact, to a drusen-dependent mechanical damage or drusen just occurs as an independent consequence of an upstream metabolic alteration, which concomitantly impairs the visual process. The present data indicate that, despite a significant difference in visual function between mild and severe AMD patients in the amount of drusen exists, a strong correlation between drusen and visual impairment does not occur. This suggests that drusen and visual deterioration develop as a consequence of similar upstream biochemical alterations but it is likely that drusen do not produce visual deterioration. This is strengthened here by extreme clinical conditions, where visual impairment is severe with a slight alteration in the planar pattern of the retina or, vice versa an extended drusenoid area occurs concomitantly with fair visual acuity, contrast sensitivity and lack of metamorphopsia. A biochemical analysis of key areas in the function of specific domains in the pigment epithelium as described in the accompanying manuscript should help to better disclose the real morpho-functional deficit, which takes place in AMD.

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.

Lack of awareness despite complex visual processing: Evidence from event-related potentials in a case of selective metamorphopsia

Visual awareness is thought to result from integration of low- and high-level processing; instances of integration failure provide a crucial window into the cognitive and neural bases of awareness. We present neurophysiological evidence of complex cognitive processing in the absence of awareness, raising questions about the conditions necessary for visual awareness. We describe an individual with a neurodegenerative disease who exhibits impaired visual awareness for the digits 2 to 9, and stimuli presented in close proximity to these digits, due to perceptual distortion. We identified robust event-related potential responses indicating 1) face detection with the N170 component and 2) task-dependent target-word detection with the P3b component, despite no awareness of the presence of faces or target words. These data force us to reconsider the relationship between neural processing and visual awareness; even stimuli processed by a workspace-like cognitive system can remain inaccessible to awareness. We discuss how this finding challenges and constrains theories of visual awareness.

Correction of perceived visual distortions using a software application and correlation to age-related macular degeneration

Purpose:

To investigate the use of software-generated corrections in neutralizing perceived distortions in age-related macular degeneration.

Methods:

A tablet-based application was utilized to elicit distortions. Five subjects (seven eyes: neovascular age-related macular degeneration and three eyes: non-neovascular age-related macular degeneration) traced the reference lines, and their distortion traces were recorded. To counter distortion, a software-generated trace was re-traced by subjects to produce a corrected trace. Final traces were superimposed on optical coherence tomography images and following distances calculated: (a) dDT: distance between distortion trace and reference line; (b) dGT: distance between software-generated trace and corrected trace; (c) dCT: distance between corrected trace and reference line. Mean percent improvement in distortion was reported. Mean effectiveness of correction was also reported by utilizing t test to compare dDT and dCT. The number of distortion traces with underlying lesions on optical coherence tomography was also analyzed.

Results:

Mean age of the subjects was 76.6 (±9.5) years. Each patient traced six reference lines and each was considered a separate case. Out of 30 cases, 17 (56.6%) elicited distortion. Mean percent improvement in distortion was 71.3 ± 23% (p < 0.05). Twelve cases (70.6%) had an underlying lesion (eight cases: disrupted photoreceptor layer and four cases: normal photoreceptor layer). Mean percent improvement in cases with normal photoreceptor layer (90.8 ± 5.45%) was higher than with abnormal photoreceptor layer (58.5 ± 7.17%) (p < 0.05). Five cases with distortion had no associated underlying lesion. Mean percent improvement in these subjects was significantly higher than those with photoreceptor layer disruption.

Conclusion:

Software-generated corrections can potentially correct for perceived distortions in patients with age-related macular degeneration, especially in cases with preserved photoreceptor layer.

A shrunken world - micropsia after a right occipito-parietal ischemic stroke

Micropsia is a rare condition in which patients perceive the outside world smaller in size than it actually is. We examined a patient who, after a right occipito-parietal stroke, subjectively reported perceiving everything at seventy percent of the actual size. Using experimental tasks, we confirmed the extent of his micropsia at 70%. Visual half-field tests showed an impaired perception of shape, location and motion in the left visual field. As his micropsia concerns the complete visual field, we suggest that it is caused by a higher-order compensation process in order to reconcile the conflicting information from the two hemifields.

IOL-Induced Extreme Blur to Alleviate Intractable Diplopia Secondary to Dragged-Fovea Diplopia Syndrome

A 73-year-old male presented with one year of intractable binocular diplopia and metamorphopsia in the right eye. He was unable to maintain fusion with prismatic correction, refused cosmetically noticeable forms of occlusion, and was not an occlusive contact lens candidate due to chronic neuropathy affecting his hands. The patient underwent cataract surgery with placement of a high plus intraocular lens to induce extreme blur. The uncomplicated procedure was successful in eliminating his diplopia. Cataract extraction with a high minus refractive target is an option for treating intractable diplopia associated with dragged-fovea diplopia syndrome.

Alice in Wonderland Syndrome as a Presenting Manifestation of Creutzfeldt-Jakob Disease

Background: Alice in Wonderland syndrome (AIWS) is a rare neurological disorder characterized by distortions of visual perception (metamorphopsias), the body image, and the experience of time, along with derealization and depersonalization. Some 85% of patients present with perceptual distortions in a single sensory modality, e.g., only visual or only somesthetic in nature. Moreover, the majority experience only a single type of distortion, e.g., only micropsia or only macropsia. AIWS has many different etiologies, and hence an extensive differential diagnosis. Its amenability to treatment depends on the underlying pathological process, which in children is mostly encephalitis, and in adults, migraine. In the literature, no more than 180 “clinical” cases of AIWS have been described (i.e., cases in need of medical attention). Of them, some 50% showed a favorable prognosis. However, non-clinical cases (i.e., fleeting, transient cases of AIWS for which no professional help is needed) have been described in up to 30% of the general population. This indicates that AIWS is perhaps not as rare as traditionally assumed, and has led some authors to conclude that, prognostically, AIWS is usually harmless.

Methods: From our own clinical practice, we describe the first known case of Creutzfeldt-Jakob Disease (CJD, Heidenhain variant) that presented with symptoms of AIWS.

Results: In our patient, disease onset was sudden and rapidly progressive, starting with isolated visual symptoms. Symptoms of AIWS comprised akinetopsia, chloropsia, micropsia, macropsia, zoom vision, and time distortions (quick-motion phenomenon and protracted duration). Soon, these were complicated by paraesthesias, gait instability, aphasia, expressive amusia, cognitive decline, and behavioral changes in the form of agitation and emotional lability. The diagnosis of probable sporadic CJD was confirmed with the aid of a head MRI and cerebrospinal fluid (14-3-3 protein). In the absence of any treatment options, our patient was discharged home and died within 2 months after his visual symptoms had begun. Autopsy consent was not obtained.

Conclusion: We conclude that AIWS is not always as harmless as sometimes suggested, and that CJD, although extremely rare, must be part of its extensive differential diagnosis, notably in the presence of rapid cognitive decline.

Patient-reported outcomes of ocriplasmin for the treatment of vitreomacular traction: a systematic review and synthesis of the literature

Purpose

Vitreomacular traction (VMT) is a disease in which the vitreous exerts abnormally strong traction on the macula, the area of the eye responsible for detailed central vision. If this traction significantly distorts the macula then VMT can lead to troublesome distorted vision (metamorphopsia), sometimes occurring despite relatively preserved visual acuity. Ocriplasmin, administered as a single intravitreal injection, aims to release VMT and improve vision. While the effect of ocriplasmin on traction release and visual acuity is well characterized, the effect of symptoms like metamorphopsia is not.

Methods

A systematic review and synthesis of the literature on patient reported outcomes (PRO) in relation to the use of ocriplasmin for the treatment of VMT was undertaken using MED-LINE and Embase databases, and the Cochrane central register of controlled trials (CENTRAL).

Results

The review identified PRO data from 870 patients across three randomized controlled trials. The most commonly reported PROs were the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25), a broad measure of vision-related quality of life, and Visual Function Response (VFR), an outcome combining quality of life and visual acuity outcomes. Treatment with ocriplasmin produced significant patient benefit vs control (sham or placebo-injection). Ocriplasmin was associated with a higher proportion of patients experiencing a clinically meaningful improvement in visual functioning with a difference of 11.8% for VFQ-25 and 23.2% for VFR responder analyses, respectively.

Conclusion

Patients with VMT have material impairment in visual functioning and quality of life, relative to their reduction in visual acuity. Ocriplasmin results in a significant improvement in visual functioning. Future research could include the development of new PROs specific to VMT.

Multi-line Adaptive Perimetry (MAP): A New Procedure for Quantifying Visual Field Integrity for Rapid Assessment of Macular Diseases

Purpose

In order to monitor visual defects associated with macular degeneration (MD), we present a new psychophysical assessment called multiline adaptive perimetry (MAP) that measures visual field integrity by simultaneously estimating regions associated with perceptual distortions (metamorphopsia) and visual sensitivity loss (scotoma).

Methods

We first ran simulations of MAP with a computerized model of a human observer to determine optimal test design characteristics. In experiment 1, predictions of the model were assessed by simulating metamorphopsia with an eye-tracking device with 20 healthy vision participants. In experiment 2, eight patients (16 eyes) with macular disease completed two MAP assessments separated by about 12 weeks, while a subset (10 eyes) also completed repeated Macular Integrity Assessment (MAIA) microperimetry and Amsler grid exams.

Results

Results revealed strong repeatability of MAP and high accuracy, sensitivity, and specificity (0.89, 0.81, and 0.90, respectively) in classifying patient eyes with severe visual impairment. We also found a significant relationship in terms of the spatial patterns of performance across visual field loci derived from MAP and MAIA microperimetry. However, there was a lack of correspondence between MAP and subjective Amsler grid reports in isolating perceptually distorted regions.

Conclusions

These results highlight the validity and efficacy of MAP in producing quantitative maps of visual field disturbances, including simultaneous mapping of metamorphopsia and sensitivity impairment.

Translational Relevance

Future work will be needed to assess applicability of this examination for potential early detection of MD symptoms and/or portable assessment on a home device or computer.

Severe Sleep Deprivation Causes Hallucinations and a Gradual Progression Toward Psychosis With Increasing Time Awake

Background: Going without sleep for long periods of time can produce a range of experiences, including perceptual distortions and hallucinations. Many questions, however, remain unanswered regarding the types of symptoms which are most reliably elicited, the time of symptom onset, and whether symptoms worsen over time toward psychotic decompensation. Since sleep deprivation exceeding 48 h is considered unethical today, an examination of historical studies with extreme sleep-loss duration is needed to obtain information about what happens during prolonged sleep loss. Methods: A systematic-review approach was used to identify experimental and observational studies of sleep deprivation in healthy people which describe the effects of prolonged sleep loss on psychopathological symptoms, without any date restriction. Results: A total of 476 articles were identified. Of these, 21 were eligible for inclusion. Duration of sleep loss ranged between 24 h and 11 nights (total 760 participants; average 72-92 h without sleep). All studies except one reported perceptual changes, including visual distortions (i.e., metamorphopsias), illusions, somatosensory changes and, in some cases, frank hallucinations. The visual modality was the most consistently affected (in 90% of the studies), followed by the somatosensory (52%) and auditory (33%) modalities. Symptoms rapidly developed after one night without sleep, progressing in an almost fixed time-dependent way. Perceptual distortions, anxiety, irritability, depersonalization, and temporal disorientation started within 24-48 h of sleep loss, followed by complex hallucinations and disordered thinking after 48-90 h, and delusions after 72 h, after which time the clinical picture resembled that of acute psychosis or toxic delirium. By the third day without sleep, hallucinations in all three sensory modalities were reported. A period of normal sleep served to resolve psychotic symptoms in many-although not all-cases. Conclusions: Psychotic symptoms develop with increasing time awake, from simple visual/somatosensory misperceptions to hallucinations and delusions, ending in a condition resembling acute psychosis. These experiences are likely to resolve after a period of sleep, although more information is required to identify factors which can contribute to the prevention of persistent symptoms.

Alice in Wonderland Syndrome: A Historical and Medical Review

Alice in Wonderland syndrome is a disorienting neurological condition that affects human perception to the senses of vision, hearing, touch, sensation, and the phenomenon of time. Individuals affected with Alice in Wonderland syndrome can experience alterations in their perception of the size of objects or their own body parts, known as metamorphopsias. It is known to occur in conditions including migraine, epilepsy, and certain intoxicants and infectious diseases. The name refers to Lewis Carrol's well-known children's book Alice's Adventures in Wonderland, in which the title character experiences alterations of sensation in which she felt that her body had grown too tall or too small, or parts of her body were changing shape, size, or relationship to the rest of her body. The syndrome was described in 1952 by Caro Lippman, and given its name in 1955 by John Todd. The metamorphopsias characteristic of this condition are also sometimes referred to as Lilliputian hallucinations, a reference to the fictional island of Lilliput in the novel Gulliver's Travels, written by Jonathan Swift in 1726. As such, many literary and medical publications have roots in the description of this syndrome. The purpose of this review is to summarize the literary and historical significance of Alice in Wonderland syndrome, as well as to provide the reader with a medical overview of the condition.

Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane: a hypothesis revisited

Pathophysiological explanations for metamorphopsia associated with retinal pathologies generally focus on photoreceptor organization disruption. However, the retinal microarchitecture is complicated, and we hypothesize that other retinal cells may also be involved. Metamorphopsia has been widely studied in eyes with epiretinal membranes and we revisit the idea that Müller cell displacement causes retinal macropsia. A PubMed query and related article search for the macula ultrastructure under normal and pathological conditions revealed an enormous amount of information, particularly ultrahigh definition optical coherence tomography and other retinal imaging modality studies. Findings of these imaging studies support our hypothesis that Müller cells, and not cone photoreceptors, are primarily responsible for macropsia in eyes with epiretinal membranes. More specifically, we conclude that displacement of Müller cell endfeet, and not photoreceptor cones, is a more likely the explanation for retinal macropsia associated with epiretinal membranes.

Surgical Results in Ocriplasmin Candidates With Symptomatic Vitreomacular Traction Syndrome

PURPOSE

To report surgical outcomes in a series of cases with symptomatic vitreomacular traction that met MIVI-TRUST (Microplasmin for intravitreous injection-traction release without surgical treatment) criteria for ocriplasmin use who underwent primary 25-gauge vitrectomy.

MATERIALS AND METHODS

A single-center retrospective chart review study was performed in patients who underwent primary 25-gauge vitrectomy for symptomatic vitreomacular traction (VTM) from January 2013 through January 2016. Pre- and postoperative visual acuity (measured by the early treatment diabetic retinopathy acuity test), and posterior hyaloid focal attachment to the macula (demonstrated by high-definition optical coherence tomography) were analyzed. In addition, intra- and postoperative complications were obtained from medical records.

RESULTS

Fifteen consecutive cases of symptomatic VMT traction that underwent primary 25-gauge vitrectomy were included. All met the MIVI-TRUST criteria for ocriplasmin use. In all cases, VMT resolution, macular hole closure, and improvement in best corrected visual acuity (BCVA) were observed. Mean visual acuity improved from 56.53 ± 16.04 letters at baseline to 73.13 ± 7.46 letters at 24 weeks of follow-up. The mean BCVA improvement from baseline was 16.60 letters (range 6-44), which was statistically significant (P < 0.0001). Ten of fifteen patients (66.6%) showed significant improvement of their BCVA to 20/40 or better (70 or more in ETDRS visual acuity test). No significant intra- or postoperative complications were documented.

CONCLUSIONS

Primary 25-gauge pars plana vitrectomy in eyes with symptomatic vitreomacular traction is able to efficiently resolve VMT and macular holes, improving vision in candidates for intravitreal injection of ocriplasmin. This well-tolerated surgical procedure may be a reliable and predictable alternative for resolving VMT pathology.

Quantifying metamorphopsia with M-CHARTS in patients with idiopathic macular hole

Purpose

The purpose of this study was to determine the degree of metamorphopsia using M-CHARTS™ in patients with idiopathic macular hole before and after pars plana vitrectomy and internal limiting membrane (ILM) peeling.

Patients and methods

The records of 22 eyes of 22 patients with a full-thickness macular hole who underwent pars plana vitrectomy and ILM peeling were reviewed. All patients underwent a complete ophthalmic examination including spectral-domain optical coherence tomography (OCT). Horizontal metamorphopsia (MH) and vertical metamorphopsia (MV) scores were determined using M-CHARTS at the same time. The time course of changes in metamorphopsia and the relationship between best-corrected visual acuity (BCVA) and OCT parameters were assessed.

Results

Sealing of the macular hole was noted in all eyes after surgery. BCVA improved significantly from 1 month after surgery (P<0.001). The MV score was significantly higher than the MH score before surgery (P<0.05) and improved significantly from 1 month after surgery (P<0.03). The MH score improved significantly at 6 months after surgery (P<0.001). The postoperative MV and MH scores became closer to one another from 1 month after surgery. Moreover, the MV score was higher than the MH score at all postoperative assessments. There was a significant correlation between the MV and MH scores at all follow-up assessments. There was no significant correlation between BCVA and the MV or MH score at any follow-up assessment.

Conclusion

The satisfaction of the patients with macular hole after surgery cannot be necessarily measured by BCVA alone, because M-scores were not correlated to BCVA in postoperative evaluation. Therefore, evaluation of the MV and MH scores can be an independent treatment outcome in addition to BCVA.

Clinical application of 3D display device in ophthalmology: measurement of metamorphopsia

PURPOSE

To develop a new tool for detecting metamorphopsia.

METHOD

Evaluation of diagnostic test. Novel tool for measuring metamorphopsia was developed using commercial 3D display. Fifty-eight patients diagnosed with macular disease, which included epiretinal membrane, age-related macular degeneration, central serous chorioretinopathy and macular hole, as confirmed by macular optical coherence tomography were tested with Amsler grid and novel method. The subjective perception of metamorphopsia and its effect on the lives of the participants with macular disease was also evaluated using a brief questionnaire. The sensitivity and specificity to subjective perception of metamorphopsia were compared.

RESULTS

The sensitivity and specificity were 66.7% and 97.7%, respectively, using the Amsler grid test, and 100% and 90.7%, respectively, using the 3D novel metamorphopsia test developed for this study.

CONCLUSIONS

The detection rate of metamorphopsia in macular disease using novel metamorphopsia test was significantly higher than that using the Amsler grid test. This novel approach to detecting for metamorphopsia can also be used at home for self-assessment.

[Idiopathic epiretinal membranes: visual function impairment, morphological and functional features of retinal involvement]

By affecting different retinal layers, an idiopathic epiretinal membrane (iERM) produces changes in macular architectonics and functioning. Morphological and functional assessment of these patients using modern visualization methods and electroretinography contributes to a better understanding of pathogenetic mechanisms of iERM.

Quantifying metamorphopsia in patients with diabetic macular oedema and other macular abnormalities

PURPOSE

To quantify subjective visual metamorphopsia in newly diagnosed patients suffering from diabetic macular oedema (DME) and other macular abnormalities and to evaluate anti-VEGF treatment effect.

METHODS

Patients with DME, subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) or retinal venous occlusion (RVO) were recruited. Metamorphopsia score (Mscore) was calculated using M-Charts at baseline and at the end of a series of anti-VEGF injections.

RESULTS

Fifteen eyes of 10 patients with DME, 14 eyes of 13 patients with AMD-CNV and five patients with RVO were included in this study. At baseline, positive Mscore was observed in 46.6% of eyes with DME, 50% of eyes with AMD-CNV and four of five eyes with RVO. Treatment led to a complete metamorphopsia reduction (Mscore = 0) in 71.4% of DME patients, 35.7% of AMD and 0% of RVO patients.

CONCLUSION

We suggest that the M-charts may serve as an additional test for diagnosis and follow-up, complementary to morphological evaluation by imaging, in diabetic patients facing their first anti-VEGF treatment.

Predictive factors for postoperative visual acuity in idiopathic epiretinal membrane: a systematic review

The aim of this study was to review the literature on predictive factors for postoperative visual acuity (VA) in surgery for idiopathic epiretinal membrane (ERM). A systematic review of the literature in the databases of PubMed and Embase was performed. The risk of bias was assessed based on predefined criteria and the results were summarized. In total, 1927 studies were retrieved of which 35 were potentially eligible. Nineteen studies were of adequate quality in terms of bias. Preoperative VA, central foveal thickness (CFT) and inner segment/outer segment (IS/OS) integrity on optical coherence tomography (OCT) were most extensively studied. Other preoperative factors studied were severity of metamorphopsia, several OCT parameters, fundus autofluorescence and multifocal electroretinogram. In the current literature, preoperative VA is the only variable consistently associated with postoperative VA. IS/OS integrity on OCT is probably associated, and the severity of metamorphopsia, cone outer segment tips integrity and fundus autofluorescence are possibly associated with postoperative VA. CFT is not associated with postoperative VA. Further studies with adequate methodological quality are needed to confirm these findings. Therefore, an overall prediction model, including different parameters, is still awaited.

Visual disorders, the prosopometamorphopsia and prosopagnosia type in the early days after the onset of brain hemorrhagic stroke--a case report

Presented case report illustrates symptoms of prosopometamorphopsia (PM) and prosopagnosia, observed in the early days after the onset of a hemorrhagic stroke resulting from a complication of endovascular treatment of intracranial aneurysms and the use of anticoagulation therapy. PM is a visual disorder in which faces are perceived as distorted. The female patient described in the present study reported that faces she looked at seemed younger or older than in reality or as if they were dirty, swollen, or with a grimace. She also experienced symptoms of prosopagnosia, which is difficulty of recognizing familiar faces of people (e.g., of her husband and daughter). In the interview 6 months after the first examination, the patient reported spontaneous withdrawal of the visual disturbances.

Visual hallucinations of autobiographic memory and asomatognosia: a case of epilepsy due to brain cysticercosis

The current study describes the case of a woman with symptomatic epilepsy due to brain cysticercosis acquired during childhood. During her adolescence, she developed seizures characterized by metamorphopsia, hallucinations of autobiographic memory and, finally, asomatognosia. Magnetic brain imaging showed a calcified lesion in the right occipitotemporal cortex, and positron emission tomography imaging confirmed the presence of interictal hypometabolism in two regions: the right parietal cortex and the right lateral and posterior temporal cortex. We discuss the link between these brain areas and the symptoms described under the concepts of epileptogenic lesion, epileptogenic zone, functional deficit zone, and symptomatogenic zone.

Metamorphopsia and letter recognition

Acuity is the most commonly used measure of visual function, and reductions in acuity are associated with most eye diseases. Metamorphopsia--a perceived distortion of visual space--is another common symptom of visual impairment and is currently assessed qualitatively using Amsler (1953) charts. In order to quantify the impact of metamorphopsia on acuity, we measured the effect of physical spatial distortion on letter recognition. Following earlier work showing that letter recognition is tuned to specific spatial frequency (SF) channels, we hypothesized that the effect of distortion might depend on the spatial scale of visual distortion just as it depends on the spatial scale of masking noise. Six normally sighted observers completed a 26 alternate forced choice (AFC) Sloan letter identification task at five different viewing distances, and the letters underwent different levels of spatial distortion. Distortion was controlled using spatially band-pass filtered noise that spatially remapped pixel locations. Noise was varied over five spatial frequencies and five magnitudes. Performance was modeled with logistic regression and worsened linearly with increasing distortion magnitude and decreasing letter size. We found that retinal SF affects distortion at midrange frequencies and can be explained with the tuning of a basic contrast sensitivity function, while object-centered distortion SF follows a similar pattern of letter object recognition sensitivity and is tuned to approximately three cycles per letter (CPL). The interaction between letter size and distortion makes acuity an unreliable outcome for metamorphopsia assessment.

Novel quantitative assessment of metamorphopsia in maculopathy

PURPOSE

Patients with macular disease often report experiencing metamorphopsia (visual distortion). Although typically measured with Amsler charts, more quantitative assessments of perceived distortion are desirable to effectively monitor the presence, progression, and remediation of visual impairment.

METHODS

Participants with binocular (n = 33) and monocular (n = 50) maculopathy across seven disease groups, and control participants (n = 10) with no identifiable retinal disease completed a modified Amsler grid assessment (presented on a computer screen with eye tracking to ensure fixation compliance) and two novel assessments to measure metamorphopsia in the central 5° of visual field. A total of 81% (67/83) of participants completed a hyperacuity task where they aligned eight dots in the shape of a square, and 64% (32/50) of participants with monocular distortion completed a spatial alignment task using dichoptic stimuli. Ten controls completed all tasks.

RESULTS

Horizontal and vertical distortion magnitudes were calculated for each of the three assessments. Distortion magnitudes were significantly higher in patients than controls in all assessments. There was no significant difference in magnitude of distortion across different macular diseases. There were no significant correlations between overall magnitude of distortion among any of the three measures and no significant correlations in localized measures of distortion.

CONCLUSIONS

Three alternative quantifications of monocular spatial distortion in the central visual field generated uncorrelated estimates of visual distortion. It is therefore unlikely that metamorphopsia is caused solely by retinal displacement, but instead involves additional top-down information, knowledge about the scene, and perhaps, cortical reorganization.

[Bilateral choroidal metastases of unknown origin: report of a case]

Nous rapportons l'observation d'un patient de 52 ans sans antécédents pathologiques notables, qui présente depuis 10 mois un flou visuel de l’œil droit et des métamorphopsies au niveau de l’œil gauche, suivies de troubles visuels très gênants et baisse importante de l'acuité visuel du coté droit, motivant une consultation. Le bilan oculaire a mis en évidence des métastases choroïdiennes bilatérales; le bilan d'extension révèle des métastases multifocales dont le site primitif est inconnu, notre patient a décédé durant les jours d'explorations.

The two-minute approach to monocular diplopia

OBJECTIVE

To describe a quick and simple diagnostic approach to monocular diplopia.

BACKGROUND

Diplopia is a common visual complain in casualty departments, general practice clinics, neurologic clinics as well as ophthalmic clinics. Monocular diplopia, however, is uncommon. Many well established clinical examination methods are available to address diplopia. Some require special equipments which are not easily available or unfamiliar outside of ophthalmic clinic. We describe a simple two-minute diagnostic approach to monocular diplopia.

CONCLUSION

Basic knowledge and understanding of simple clinical examination techniques enhances diagnostic skill and allow proper localization of underlying disorders.