THE IMPACT OF EARLY SURGICAL INTERVENTION ON ANISEIKONIA IN PATIENTS WITH EPIRETINAL MEMBRANE: A Prospective Cohort Study.

PURPOSE: To investigate the efficacy of early surgical intervention in ameliorating aniseikonia among patients with epiretinal membrane. METHODS: This prospective cohort study enrolled patients who underwent surgery for epiretinal membrane. Patients were divided into early (symptom onset within 1 year) and late (symptom onset ≥1 year) treatment groups. Changes in aniseikonia, best-corrected visual acuity, and tangential retinal displacement were assessed and compared at 6 and 12 months postoperatively. RESULTS: Of the 56 patients, 30 (53.6%) belonged to the early treatment group and 26 (46.4%) to the late treatment group. The early treatment group demonstrated a significant reduction in aniseikonia score at 6- and 12-month follow-up visits (-1.10 ± 1.50 [P = 0.002] and -1.18 ± 1.79 [P = 0.003], respectively); however, no improvement was observed in the late treatment group (0.98 ± 4.62 [P = 0.310] and 1.52 ± 4.35 [P = 0.124], respectively). The early treatment group showed larger tangential retinal displacement at the 12-month postoperative follow-up visit. In addition, the amount of tangential retinal displacement was associated with postoperative changes in aniseikonia. CONCLUSION: Early surgical intervention is helpful in improving aniseikonia in patients with epiretinal membrane. The degree of recovery in inner retinal displacement was associated with the improvement of aniseikonia.

LONG-TERM CHANGES IN VISUAL FUNCTION AND EN FACE OPTICAL COHERENCE TOMOGRAPHY FINDINGS IN FOVEA-OFF RETINAL DETACHMENT: A 2-Year Prospective Study.

PURPOSE: To investigate the long-term changes in visual function and outer retinal abnormalities on en face optical coherence tomography after fovea-off rhegmatogenous retinal detachment and to assess associations between functional outcomes and outer retinal abnormalities. METHODS: Prospective, observational study. The following data were collected at 1, 3, 6, 12, and 24 months after retinal reattachment: Best-corrected visual acuity, metamorphopsia (M-CHARTS), aniseikonia (New Aniseikonia Test), altered ellipsoid zone reflectivity, outer retinal folds, macular detachment demarcation, and subfoveal fluid. RESULTS: Thirty-eight patients were included. Best-corrected visual acuity improved significantly from 1 to 12 months and from 12 to 24 months (P < 0.001; P = 0.022). Vertical and horizontal metamorphopsia improved significantly from 1 to 12 months (P < 0.001; P = 0.002), and at 24 months, scores of ≥0.2° were present in 54% and 42% of patients, respectively. The degree of aniseikonia did not change. Best-corrected visual acuity and aniseikonia scores were positively associated with outer retinal fold (r 0.4, P = 0.009; r 0.4, P = 0.048). A gradual normalization of outer retinal reflectivity took place during 24 months. CONCLUSION: Visual acuity improved significantly during the second year after reattachment surgery for fovea-off rhegmatogenous retinal detachment, in parallel with normalization of outer retinal abnormalities on en face optical coherence tomography. Metamorphopsia did not improve after 12 months, and aniseikonia remained unchanged.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY MORPHOLOGY AFTER RHEGMATOGENOUS RETINAL DETACHMENT REPAIR: ALIGN Post Hoc Analysis.

PURPOSE: To compare foveal avascular zone (FAZ) geometric indices using optical coherence tomography angiography (OCTA) in pneumatic retinopexy (PnR) versus pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD). FAZ morphology was assessed as a possible imaging feature of retinal displacement. METHODS: This ALIGN post hoc analysis included primary fovea-off RRDs that underwent successful PnR or PPV, and performed OCTA, and fundus autofluorescence at (FAF) 3 months postoperatively at St. Michael's Hospital, Toronto, Canada. FAZ area (mm 2 ), axial ratio, circularity, and roundness were measured, and FAF images were assessed for retinal displacement. RESULTS: Seventy-two patients were included, 78% (56/72) were male mean age was 60 ± 9 years, and 60% (43/72) were phakic. Sixty-five percent (47/72) and 35% (25/72) underwent PnR and PPV, respectively. The mean baseline logarithm of the minimum angle of resolution visual acuity was 1.49 ± 0.76. FAZ circularity was lower after PPV (0.629 ± 0.120) versus PnR (0.703 ± 0.122); P = 0.016. Sixty-six patients had gradable FAF images. Retinal displacement was present in 29% (19/66), 84.2% (16/19) of which had displacement in the macula. FAZ circularity was lower in eyes with displacement in the macula (0.613 ± 0.110) versus those without displacement (0.700 ± 0.124); P = 0.015. There was a moderate negative correlation between 12-month aniseikonia and FAZ circularity(r = -0.262; P = 0.041). CONCLUSION: FAZ circularity was lower after PPV and in eyes with retinal displacement in the macula. Circularity was negatively correlated with 12-month aniseikonia scores. FAZ circularity may be another imaging feature to consider postoperatively after RRD repair.

Measurement of Aniseikonia Tolerance in Binocular Fusion.

SIGNIFICANCE: The determination of aniseikonia tolerance may aid in developing optimal treatment plans for cataract surgery, refractive surgery, and refractive correction with glasses and contact lenses. PURPOSE: This study aimed to measure aniseikonia tolerance. METHODS: We included 33 patients (mean age ± standard deviation, 28.9 ± 6.4 years; male/female, 12:21) with anisometropia ≤1.0 D and best spectacle-corrected visual acuity of 20/20 or more in both eyes, with no ophthalmologic disease other than refractive errors and no history of ocular surgery. The exclusion criteria were anisometropia >1.0 D, axial length difference >0.5 mm, corneal refractive power difference >0.5 D, astigmatism >3.0 D, stereoacuity threshold >100 arcsec according to the Titmus Stereo Test, and >0% aniseikonia according to the New Aniseikonia Test. Aniseikonia tolerance was assessed using Eyemark Hello, a haploscope using gaze detection technology. Although the optotype of one eye was enlarged or reduced at a speed of 2%/s, the patients were instructed to press a button on the controller to indicate blurring, flickering, and diplopia. The value at which the patient responded was considered the aniseikonia tolerance value and assessed thrice per eye, five times if the values were highly variable, and then averaged. RESULTS: The mean aniseikonia tolerance was approximately 3%; the median value was approximately 2% (range, 1.0 to 11.5%; dominant eye, 3.3 ± 2.6%; nondominant eye, 2.9 ± 1.8%). No significant difference in aniseikonia tolerance between the dominant and nondominant eyes was observed for the enlarged optotypes. No case showed changes in the ocular alignment before discomfort occurred. No significant correlation was observed between aniseikonia tolerance and anisometropia, axial length difference, corneal power difference, and ocular deviation. CONCLUSIONS: Aniseikonia should be maintained at <2% for a comfortable visual environment. Aniseikonia tolerance may be an important indicator for cataract surgery, refractive surgery, and spectacle correction.

Comparison of surgical outcomes after removal of epiretinal membrane associated with retinal break and idiopathic epiretinal membrane.

PURPOSE: To compare the surgical outcomes of epiretinal membranes (ERMs) associated with retinal break and idiopathic ERMs. METHODS: This retrospective study included patients with an idiopathic ERM or an ERM associated with retinal break, who were followed up for ≥ 6 months after ERM removal. The postoperative functional and anatomical outcomes were compared between the groups. RESULTS: A total of 160 and 38 eyes (198 patients) were in the idiopathic and retinal break groups, respectively. There was no significant difference in the baseline anatomical and functional parameters between the groups. At 6 months after surgery and at the final follow-up, best-corrected visual acuity, central foveal thickness, and ectopic inner foveal layer improved significantly in both groups, but there was no significant difference between the groups. In latter 49.0% of patients, tests for metamorphopsia and aniseikonia were performed. There was a significant improvement in the scores of metamorphopsia (0.40 ± 0.38 to 0.27 ± 0.28; p < 0.001) and aniseikonia (6.07 ± 4.46 to 4.11 ± 3.52; p < 0.001) in the idiopathic group at 6 months after surgery, but not in the retinal break group. The idiopathic group had significantly greater circularity of ERM extent compared to the retinal break group (p = 0.025). CONCLUSION: Visual and anatomical improvements after removal of ERMs associated with retinal break and idiopathic ERMs were comparable. However, metamorphopsia and aniseikonia improved only after removal of idiopathic ERMs.

The effects of optically and digitally simulated aniseikonia on stereopsis.

PURPOSE: To simulate both lens-induced and screen-induced aniseikonia, and to assess its influence on stereopsis. Additionally, to determine if screen-based size differences could neutralise the effects of lens-induced aniseikonia. METHOD: A four-circle (4-C) paradigm was developed, where one circle appears in front or behind the others because of crossed or uncrossed disparity. This stereotest was used for three investigations: (1) Comparison with the McGill modified random dot stereogram (RDS), with anisometropia introduced with +2 D spheres and cylinders, and with aniseikonia introduced with 6% overall and 6% meridional (×180, ×90) magnifiers before the right eye; (2) Comparison of lens-induced and screen-induced 6% overall and meridional magnifications and (3) Determining if lens and screen effects neutralised, by opposing 6% lens-induced magnification to the right eye with screen-inducements of either 6% left eye magnification or 6% right eye minification. A pilot study of the effect of masking versus not masking the surround was also conducted. RESULTS: The 4-C test gave higher stereo-thresholds than the RDS test by 0.5 ± 0.2 log units across both anisometropic and aniseikonic conditions. However, variations in power, meridian and magnification affected the two tests similarly. The pilot study indicated that surround masking improved neutralisation of screen and lens effects. With masking, lens-induced and screen-induced magnifications increased stereo-thresholds similarly. With lens and screen effects opposed, for most participants stereo-thresholds returned to baseline for overall and ×180 magnifications, but not for ×90 magnification. Only three of seven participants showed good compensation for ×90 magnification. CONCLUSIONS: Effects of lens-induced aniseikonia on stereopsis cannot always be successfully simulated with a screen-based method. The ability to neutralise refractive aniseikonia using a computer-based method, which is the basis of digital clinical measurement, was reasonably successful for overall and ×180 meridional aniseikonia, but not very successful for ×90 aniseikonia.

Aniseikonia and visual functions with optical correction and after refractive surgery in axial anisometropia.

PURPOSE: To evaluate differences in the subjective aniseikonia and stereoacuity in patients with axial anisometropia after full correction of the refractive error with spectacles, contact lenses, and refractive surgery. METHODS: A prospective study was performed in Cairo University Hospitals on 20 patients with axial anisometropia caused by unilateral myopia > 5 D with > 4 D inter-ocular difference in spherical equivalent who were suitable candidates for excimer laser ablation (LASIK) or implantable collamer lens implantation (ICL). All patients had measurement of best-corrected visual acuity (BCVA), fusion, stereoacuity, and magnitude of aniseikonia with spectacles, contact lenses, and after surgery. RESULTS: The mean age at time of surgery was 25.7 ± 3.1 years. There were no statistically significant differences in the BCVA or stereoacuity with spectacles, contact lenses, or after refractive surgery. Microkonia < 5%) was perceived with spectacles in 8 patients (40%) and remained unchanged in 7 of these 8 patients with contact lenses. Following LASIK (n = 11), there was an induced macrokonia < 2% in 4 patients (36%), persistent microkonia of 3% in 1 patient (9%), and no change in image size in 6 (55%) patients. Following ICL implantation (n = 9), there was a perceived macrokonia of 2% in 4 patients (44%), disappearance of microkonia in 1 patient (11%) and no change in 4 patients (44%). CONCLUSIONS: Differences in BCVA, stereoacuity, and aniseikonia after correction of anisometropia by glasses, contact lens and surgery are both clinically and statistically insignificant. Retinal or neural adaptation might have a role in correction for differences in image size.

Preoperative aniseikonia is a prognostic factor for postoperative stereopsis in patients with unilateral epiretinal membrane.

PURPOSE: To investigate stereopsis and other visual functions in patients with unilateral epiretinal membrane (ERM) and to identify vision-related parameters affecting stereopsis. METHODS: This prospective study included 63 consecutive patients who were scheduled to undergo vitrectomy for unilateral idiopathic ERM. We examined stereopsis (Titmus Stereo Test, TST; TNO stereotest, TNO), best-corrected visual acuity (BCVA), letter contrast sensitivity, severity of metamorphopsia, and degree of aniseikonia preoperatively and 6 months postoperatively. RESULTS: Preoperatively, we observed significant correlation between TST scores and other vision-related parameters except severity of metamorphopsia and between TNO score and all the vision-related parameters. Multiple regression analysis showed that preoperative TST and TNO scores were significantly associated with the degree of aniseikonia (both P < 0.01). ERM surgery significantly improved stereopsis, BCVA, contrast sensitivity, and metamorphopsia, but not aniseikonia. Postoperatively, TST was significantly associated with BCVA, and TNO showed association with BCVA and aniseikonia. Postoperative TST and TNO scores showed significant correlation with preoperative aniseikonia (P < 0.005 and P < 0.001, respectively). CONCLUSIONS: Impairment of stereopsis in patients with unilateral ERM was considered to be due to retinally induced aniseikonia. Aniseikonia did not improve by surgery, and preoperative aniseikonia can be a prognostic factor for postoperative stereopsis.

CORRELATION BETWEEN MACULAR MICROSTRUCTURES AND ANISEIKONIA AFTER IDIOPATHIC EPIRETINAL MEMBRANE REMOVAL.

PURPOSE: To analyze the correlation between preoperative measurements of macular microstructures and aniseikonia after epiretinal membrane removal. METHODS: This retrospective study included 32 eyes of 32 patients who underwent epiretinal membrane surgery and were followed up for 12 months. Spectral-domain optical coherence tomography was used to measure the thicknesses of the ganglion cell layer-inner plexiform layer, inner nuclear layer (INL), and outer retinal layer in macular microstructures. The new aniseikonia test was used to measure vertical and horizontal aniseikonia scores. RESULTS: There was a significant decrease in central macular thickness and ganglion cell layer-inner plexiform layer thickness at 6 and 12 months postoperatively (all P < 0.001). Vertical aniseikonia scores, horizontal aniseikonia scores, and INL and outer retinal layer thicknesses did not show significant changes. Vertical aniseikonia scores and horizontal aniseikonia scores were significantly associated with INL thicknesses of each meridian at each follow-up time point (all P < 0.05). Preoperative vertical and horizontal INL thicknesses were correlated with vertical aniseikonia scores and horizontal aniseikonia scores at 12 months postoperatively (P = 0.014 and P = 0.002, respectively). CONCLUSION: Aniseikonia values did not change after epiretinal membrane removal and were associated with INL thickness before and after surgery. Thus, preoperative INL thickness could be used as a predictor of surgical prognosis in epiretinal membrane patients.

Field-wide Quantification of Aniseikonia Using Dichoptic Localization.

SIGNIFICANCE: We validated a novel paradigm to measure aniseikonia across the visual field and used a mathematical approach that is able to describe the magnitude and shape of aniseikonia in a concise, clinically meaningful fashion. PURPOSE: The measurement of aniseikonia has been performed clinically for more than half a century; however, amalgamation of field-wide local variations in binocular spatial localization into clinically applicable global metrics has yet to be attempted. Thus, the goal of the current study was twofold: first, to measure field-wide aniseikonia and second, to compare how local and global metrics each capture optically induced aniseikonia. METHODS: Twelve visually normal observers performed a dichoptic localization task at 24 locations in the visual field. This was done in four conditions: (A) while wearing red-green filters, (B) while wearing green-red filters, (C) while wearing a monocular 5% overall size lens, and (D) while wearing a monocular 6% meridional size lens. The physical settings at perceptual equality were then used to compute both local (relative magnification) and global (coefficients for Zernike terms) descriptors of aniseikonia. RESULTS: The comparison of each lens condition to the baseline condition confirmed predicted shifts in both the sign and magnitude of aniseikonia at both the local and global levels; however, the intraobserver levels of precision were moderate, and systematic underestimations were present across all locations in conditions C and D. CONCLUSIONS: Local and global analyses derived from dichoptic localization data were both able to capture optically induced changes in binocular spatial perception; however, solutions that address the diagnostic and therapeutic challenges associated with this paradigm are needed before clinical implementation can proceed.

Effects of simulated anisometropia and aniseikonia on stereopsis.

PURPOSE: Stereopsis depends on horizontally disparate retinal images but otherwise concordance between eyes. Here we investigate the effect of spherical and meridional simulated anisometropia and aniseikonia on stereopsis thresholds. The aims were to determine effects of meridian, magnitude and the relative effects of the two conditions. METHODS: Ten participants with normal binocular vision viewed McGill modified random dot stereograms through synchronised shutter glasses. Stereoacuities were determined using a four-alternative forced-choice procedure. To induce anisometropia, trial lenses of varying power and axes were placed in front of right eyes. Seventeen combinations were used: zero (no lens) and both positive and negative, 1 and 2 D powers, at 45, 90 and 180 axes; spherical lenses were also tested. To induce aniseikonia 17 magnification power and axis combinations were used. This included zero (no lens), and 3%, 6%, 9% and 12% at axes 45, 90 and 180; overall magnifications were also tested. RESULTS: For induced anisometropia, stereopsis loss increased as cylindrical axis rotated from 180° to 90°, at which the loss was similar to that for spherical blur. For example, for 2 D meridional anisometropia threshold increased from 1.53 log sec arc (i.e. 34 sec arc) for x 180 to 1.89 log sec arc (78 sec arc) for x 90. Anisometropia induced with either positive or negative lenses had similar detrimental effects on stereopsis. Unlike anisometropia, the stereopsis loss with induced meridional aniseikonia was not affected by axis and was about 64% of that for overall aniseikonia of the same amount. Approximately, each 1 D of induced anisometropia had the same effect on threshold as did each 6% of induced aniseikonia. CONCLUSION: The axes of meridional anisometropia but not aniseikonia affected stereopsis. This suggests differences in the way that monocular blur (anisometropia) and interocular shape differences (aniseikonia) are processed during the production of stereopsis.

Comparison of blur and magnification effects on stereopsis: overall and meridional, monocularly- and binocularly-induced.

PURPOSE: To determine whether monocularly- and binocularly-induced spherical and meridional blur and aniseikonia had similar effects on stereopsis thresholds. METHODS: Twelve participants with normal binocular vision viewed McGill modified random dot stereograms to determine stereoacuities in a four-alternative forced-choice procedure. Astigmatism was induced by placing trial lenses in front of the eyes. Twenty-three conditions were used, consisting of zero (no lens), +1 D and +2 D spheres and cylinders at axes 180, 45 and 90 in front of the right eye, and the following binocular combinations of both lens powers: R × 180/L × 180, R × 45/L × 45, R × 90/L × 90, R sphere/L sphere, R × 180/L × 90, R × 45/L × 135, R × 90/L × 180. Aniseikonia was induced by placing magnifying lenses in front of the eyes. Twenty-three conditions were used, consisting of zero, 6% and 12% overall magnification and both magnifications at axes 180, 45 and 90 in front of the right eye only, and the following binocular combinations using 3% and 6% lenses: R × 90/L × 90, R × 45/L × 45, R × 180/L × 180, R overall/L overall, R × 90/L × 180, R × 45/L × 135, and R × 180/L × 90. RESULTS: Stereopsis losses for binocular blur effects with parallel axes (non-anisometropic) were the same as for monocular blur effects of the same axes, and these were strongly dependent on axis (spherical blur and ×90 had the greatest effects). Binocular blur effects with orthogonal axes had greater effects than with parallel axes, with the axis combination of the former having no effect (e.g. R × 90/L × 180 was similar to R × 45/L × 135). For induced aniseikonia, splitting the magnifications between the eyes improved stereopsis slightly, and the effects were not dependent on axis. CONCLUSION: Binocular blur affects stereopsis similarly to monocular meridional blur if axes in the two eyes are parallel, whereas the effect is greater if the axes are orthogonal. In meridional aniseikonia, splitting magnification between the right and left lenses produces a small improvement in stereopsis that is independent of axis direction and right/left combination.

Dynamics of the accommodative response under artificially-induced aniseikonia.

Aniseikonia has demonstrated to deteriorate the binocular function, however its impact on the accommodative response remains unknown. The present study aimed to analyze the effects of artificially-induced aniseikonia, using afocal magnifiers, on the dynamics of the accommodative response. The magnitude and variability of the accommodative response were objectively measured in 20 young healthy subjects by a binocular open-field autorefractometer. Participants observed a static stimulus for 90 s, under seven degrees of aniseikonia (0%, 1%, 3%, 5%, 8%, 10% and 12%), and at three distances (500 cm, 40 cm and 20 cm). Complementarily, near stereoacuity, and perceived levels of fatigue and visual discomfort were assessed. The degree of induced aniseikonia was associated with the magnitude of the accommodative response (p < 0.001, ηp2 = 0.329), obtaining a statistically significant reduced accommodative lag for the induced aniseikonia conditions of 8%, 10% and 12% in comparison to the control condition at 40 cm (p-corrected = 0.019, <0.001 and 0.013, respectively) and at 20 cm (p-corrected < 0.001, <0.001 and 0.003, respectively). However, the degree of induced aniseikonia did not reveal any effect on the variability of accommodation (p > 0.05). We also found a decline in near stereoacuity and an increment of visual symptomatology when inducing aniseikonia (p < 0.05). Our data evidenced that greater degrees of induced aniseikonia cause a heightened accommodative response. These preliminary findings may be of relevance for patients undergoing cataract or refractive surgery procedures in which aniseikonia can be induced.

Relationship between the morphology of the foveal avascular zone and the degree of aniseikonia before and after vitrectomy in patients with unilateral epiretinal membrane.

PURPOSE: Persistent metamorphopsia, particularly aniseikonia, is a troublesome problem which may occur after epiretinal membrane (ERM) surgery. To clarify if the preoperative foveal avascular zone (FAZ) morphology can be used as a predictor of postoperative residual aniseikonia, the morphological changes in the FAZ and the degree of aniseikonia between before and 12 months after vitrectomy for epiretinal membrane (ERM) were measured and analyzed. METHODS: Thirty patients, each with a unilateral idiopathic ERM, who underwent treatment between September 2016 and March 2017 were enrolled for this prospective case series study. Best-corrected visual acuity (BCVA), the degree of aniseikonia, central foveal thickness (CFT), FAZ area (FAZa), perimeter (FAZp), and circularity in ERM eyes were examined before and 1, 3, 6 and 12 months after surgery. The fellow eye without an ERM was also examined and used as the control. The interocular ratios of the CFT, FAZa, and FAZp in ERM eyes with those in control eyes were also calculated. Multiple regression analysis was performed on preoperative parameters that were found to be significantly correlated with the 12-month aniseikonia in univariate analyses. RESULTS: The BCVA in the ERM eyes was significantly improved at 1 month after surgery (P < .0001) The degree of aniseikonia was significantly reduced only after 12 months (P = .004). The CFT had decreased significantly by 3 months after the surgery and continued decreasing thereafter (P < .0001). Both FAZa and FAZp were significantly smaller in the ERM eyes than in the control eyes throughout the study period (P < .0001 and P < .0001, respectively), with no change in either parameter over the study period. Correlation analyses revealed that the degree of aniseikonia was significantly correlated with pre- and postoperative CFT, CFT ratio, FAZa, FAZa ratio, FAZp, and FAZp ratio. Within preoperative OCT parameters, FAZa ratio remained significant after multiple regression analysis was performed (P < .0001). CONCLUSIONS: Aniseikonia changed little over the long term following ERM surgery. Preoperative FAZ area ratio was identified as a significant predictor of postoperative aniseikonia.

Topical Review: Retinally Induced Aniseikonia.

SIGNIFICANCE: We review retinally induced aniseikonia, an underrecognized condition resulting from common retinal conditions that has a significant effect on quality of life. Optometrists can influence the timing of surgical intervention to mitigate the damage from delaying surgical intervention in patients whose other findings do not meet a surgeon's treatment threshold.Aniseikonia due to optical differences between the eyes occurs in 1 to 3.5% of the population and can hinder the quality of binocular vision. The less noted retinally induced aniseikonia is due to mechanical distortion and displacement of the retinal photoreceptors and occurs with disorders such as epiretinal membrane, reattached retinal detachment, macular hole, and macular edema. Despite that it was first reported in 1950 and its incidence continues to rise in the aging population, many eye care practitioners are unaware of this condition, which can persist or even be exacerbated after treatment as a contributing cause of binocular vision symptoms. The purpose of this report is to allow more eye care practitioners to become familiar with retinally induced aniseikonia. The review of the literature includes demographics and epidemiology, etiology, pathogenesis, diagnosis, results of treatment, prognosis, and case examples.

POSTOPERATIVE CHANGES AND PROGNOSTIC FACTORS OF VISUAL ACUITY, METAMORPHOPSIA, AND ANISEIKONIA AFTER VITRECTOMY FOR EPIRETINAL MEMBRANE.

PURPOSE: To investigate postoperative changes and prognostic factors of visual impairment after vitrectomy for unilateral epiretinal membrane. METHODS: A prospective observational study on 45 eyes from 45 patients with unilateral idiopathic epiretinal membrane who underwent vitrectomy. Visual parameters (best-corrected visual acuity, metamorphopsia using M-CHARTS, and aniseikonia using the New Aniseikonia Test) and spectral domain optical coherence tomography parameters (macular retinal layer thickness and microstructure of the outer retina) were measured preoperatively and 6 and 12 months postoperatively. Statistical analyses included linear mixed-effects models for the longitudinal changes and prognostic factors of visual parameters. RESULTS: Best-corrected visual acuity and horizontal metamorphopsia improved significantly from 6 months after surgery (P < 0.001), whereas aniseikonia decreased significantly only at 12 months (P = 0.015). Vertical metamorphopsia remained unchanged. Preoperative inner nuclear layer thickness was significantly correlated with preoperative metamorphopsia. Besides baseline values, best-corrected visual acuity had no significant prognostic factors, but preoperative ellipsoid zone disruption had a negative direction of association with postoperative metamorphopsia (coefficients: -0.37 and -0.62, P = 0.015 and 0.006 for horizontal and vertical metamorphopsia, respectively), and preoperative horizontal metamorphopsia had a positive direction of association with postoperative aniseikonia (coefficient: 1.77, P = 0.002). CONCLUSION: After vitrectomy, postoperative changes and prognostic factors for unilateral epiretinal membrane differed for best-corrected visual acuity, metamorphopsia, and aniseikonia.

Aniseikonia in various retinal disorders.

PURPOSE: The purpose was to quantify and compare the severity of aniseikonia in patients undergoing vitrectomy for various retinal disorders. METHODS: We studied 357 patients with retinal disorders including epiretinal membrane (ERM), macular hole (MH), cystoid macular edema with branch / central retinal vein occlusion (BRVO-CME / CRVO-CME), diabetic macular edema (DME), macula-off rhegmatogenous retinal detachment (M-off RD), and macula-on RD (M-on RD) as well as 31 normal controls. The amount of aniseikonia was measured using the New Aniseikonia Test preoperatively and at 6 months postoperatively. RESULTS: Of all patients, 59% presented aniseikonia. Preoperative and postoperative mean aniseikonia were 4.0 ± 4.1% and 3.0 ± 3.6%, respectively. In particular, 68% of patients with ERM had macropsia, and approximately half of MH, RVO-CME, DME, and M-off RD patients had micropsia. Preoperative aniseikonia was significantly severe in ERM than in other disorders. Vitrectomy improved aniseikonia only in MH, while visual acuity was improved in all disorders except CRVO-CME. CONCLUSION: More than half of the patients showed aniseikonia preoperatively. A majority of ERM patients exhibited macropsia, whereas MH, RVO-CME, DME, and macula-off RD patients presented micropsia. The aniseikonia score was greatest in ERM patients. In most retinal disorders, surgery significantly improved visual acuity, but not aniseikonia.

Aniseikonia and Foveal Microstructure in Patients with Idiopathic Macular Hole.

PURPOSE: To quantify the severity of aniseikonia in patients undergoing vitrectomy for idiopathic macular hole (MH) and to examine any relationship between aniseikonia and the foveal microstructure. DESIGN: Prospective, consecutive, interventional case series. PARTICIPANTS: We included 56 eyes of 56 patients who underwent vitrectomy to treat idiopathic MH. METHODS: We examined visual acuity, aniseikonia using the New Aniseikonia Test, and foveal structure using optical coherence tomography (OCT) before and 3, 6, and 12 months after surgery. Based on OCT images, minimum and base diameters of MH, height of MH, and defect lengths of the external limiting membrane (ELM), ellipsoid zone, and interdigitation zone were assessed. MAIN OUTCOME MEASURES: Degree of aniseikonia before and after surgery. RESULTS: The mean aniseikonia was -3.2±4.6%, ranging from -15.5% to +5.0%. Of the patients, 55% had micropsia, 7% had macropsia, and 38% had no aniseikonia. The mean absolute value of aniseikonia improved significantly from 3.8±4.1% before surgery to 1.0±1.5% at 12 months after surgery (P < 0.0001). The preoperative mean absolute value of aniseikonia showed a significant correlation with minimum diameters of MH (P < 0.01), base diameters of MH (P < 0.01), and the defect length of ELM (P < 0.05). In multivariate analysis, preoperative aniseikonia showed a significant correlation with the defect length of ELM (P < 0.05). In contrast, postoperative aniseikonia was not associated with any of the parameters. CONCLUSIONS: Approximately half of MH patients had micropsia. Vitrectomy for MH improved aniseikonia. Preoperative aniseikonia was associated with MH size and the defect length of ELM.

RESTORATION OF RETINALLY INDUCED ANISEIKONIA IN PATIENTS WITH EPIRETINAL MEMBRANE AFTER EARLY VITRECTOMY.

PURPOSE: To evaluate changes in aniseikonia in patients with unilateral epiretinal membrane after surgery. METHODS: This prospective study included 24 patients with unilateral idiopathic epiretinal membrane who underwent vitrectomy. Best-corrected visual acuity and aniseikonia were measured using the Aniseikonia Inspector 3 (Optical Diagnostics, Culemborg, The Netherlands) preoperatively and 6 months postoperatively. Aniseikonia was measured in vertical and horizontal directions. RESULTS: Mean age at surgery was 64.2 ± 9.3 years, and mean symptom duration was 12.9 ± 11.4 months. Mean changes in aniseikonia after surgery were 41.0 ± 31.4% reduction in the vertical direction and 41.6 ± 30.8% reduction in the horizontal direction (both P < 0.001). The remaining aniseikonia after surgery correlated with symptom duration (r = 0.565, P = 0.006, and r = 0.812, P < 0.001, for vertical and horizontal directions, respectively). The good preoperative best-corrected visual acuity group showed better improvement of aniseikonia than did the poor preoperative group (P = 0.046 and P = 0.025 for vertical and horizontal directions, respectively). CONCLUSION: Greater improvement of aniseikonia after epiretinal membrane peeling was achieved in patients with better preoperative best-corrected visual acuity and shorter symptom durations. Early vitrectomy helped to reduce aniseikonia in patients with epiretinal membrane.

Aniseikonia induced by cataract surgery and its effect on binocular vision.

PURPOSE: This study measured aniseikonia before and after the first and second cataract surgeries in ametropic adults. The relationship of aniseikonia to anisometropia and its effect on stereopsis, ocular alignment, and clinical symptoms were determined. METHODS: Seventeen patients scheduled to have bilateral cataract surgery with 2 diopters or more ametropia participated. Patients were evaluated before cataract surgery and 4 weeks (±1 week) after the first and second surgery. Visual acuity, refractive error, aniseikonia, stereopsis, ocular alignment, and visual symptoms were determined at each visit. RESULTS: Aniseikonia increased after the first cataract surgery. The increase in aniseikonia occurred in concert with increased anisometropia and resulted in poorer stereopsis overall. Aniseikonia and anisometropia 1 month (±1 week) after the second cataract surgery returned to near baseline and were associated with better stereopsis. The amount of aniseikonia showed substantial variance and could not be predicted by the amount of induced anisometropia. Changes in ocular alignment were minimal. Statistically significant changes in patient symptoms between study visits were infrequent. CONCLUSIONS: Aniseikonia induced by cataract surgery may not be a substantial problem for ametropic adults with normal binocular vision, at least in the short term.