Aniseikonia: A 21st Century Look.

Purpose: Aniseikonia, an appreciation of image size differences between the eyes, can produce symptoms in patients, ranging from headaches to loss of fusion. The purpose of this research was to take a 21st century look at aniseikonia. Methods: Kellogg Eye Center patient records were evaluated for measurable aniseikonia in patients tested with the Aniseikonia Helper, a tablet-based application. Anaglyph slides for the synoptophore were developed to test the limits of induced aniseikonia on stereopsis and fusion. A survey was developed to determine how frequently members of the American Association of Certified Orthoptists (AACO) examine and treat patients with aniseikonia.Results: The prevalence of measurable aniseikonia in this cohort was 7.8%. Moderate amounts of induced aniseikonia, 4% induced image size disparity, disrupt fusion and can cause a loss of stereopsis. Eighty percent of responding AACO members see patients with aniseikonia and among those, 25% see them on a monthly basis. Treatment options, other than wearing contact lenses, are limited to occlusion or fogging techniques. Conclusions: Aniseikonia remains a frequent complaint among patients. The ophthalmologic community needs to use the best methods for measuring aniseikonia and to develop better methods for treating aniseikonia.

Comparison of visual acuity, metamorphopsia, and aniseikonia in patients with an idiopathic epiretinal membrane.

PURPOSE: The clinical course of reduced visual acuity, metamorphopsia, and aniseikonia are dissimilar in patients with an epiretinal membrane (ERM). We measured and compared the best-corrected visual acuity (BCVA), metamorphopsia, and aniseikonia of patients with ERM. METHODS: We measured metamorphopsia and aniseikonia horizontally as well as vertically with the M-CHART (MH and MV) and New Aniseikonia Test (NATH and NATV) in 61 patients with unilateral idiopathic ERM. We compared the BCVA with the other values. Comparisons between the MH and the NATV and between the MV and the NATH were performed, because the MH assesses vertical metamorphopsia, and the MV, horizontal metamorphopsia. RESULTS: BCVA was not significantly correlated with the other values (MH vs BCVA: P = .69; MV vs BCVA: P = .114; NATH vs BCVA: P = .656; NATV vs BCVA: P = .935). The MH and NATV magnitudes were significantly correlated, but the correlation coefficient was small (P = .007, r = 0.343); no significant correlation was found between the MV and NATH magnitudes (P = .065). We found patients with aniseikonia, but no metamorphopsia (n = 6), and more patients with metamorphopsia, but no aniseikonia (n = 11). Only 23 patients had coincident directions of metamorphopsia and aniseikonia. CONCLUSIONS: The magnitudes of metamorphopsia and aniseikonia were not closely correlated and their directions did not coincide in most patients. Neither the M-CHARTS nor the NAT measurements correlated with the BCVA. Quantitative testing of metamorphopsia and aniseikonia in addition to that for BCVA is necessary to assess visual function in patients with ERM.

Prevalence and Associations of Central-Peripheral Rivalry-Type Diplopia in Patients With Epiretinal Membrane.

Importance: The prevalence and clinical associations of patients with epiretinal membrane (ERM) who develop central-peripheral rivalry (CPR)­type diplopia are unknown. Objectives: To determine the prevalence of CPR-type diplopia in retinal disease clinic patients with ERM and to determine clinical findings associated with CPR-type diplopia. Design, Setting and Participants: A prospective cross-sectional study of 31 patients with ERM from retinal disease clinics to determine the prevalence of CPR-type diplopia. A retrospective case cohort of 25 additional patients with ERM, selected from adult strabismus clinics, was added (total = 56) to determine clinical associations with CPR-type diplopia. All data were collected between June 2014 and November 2016; prospective cohort data were collected from June 2016 to November 2016. Main Outcomes and Measures: The presence of diplopia was determined by patient history and diplopia questionnaire responses. Visual acuity and ocular alignment were recorded. Metamorphopsia was documented qualitatively by evaluation of the door frame and Amsler grid and measured quantitatively using M-charts and D-charts. Aniseikonia was determined by subjective description and results of the Awaya new aniseikonia test. Retinal misregistration testing consisted of optotype-frame test and synoptophore; CPR-type diplopia was defined as diplopia associated with evidence of retinal misregistration when other causes did not fully explain diplopia. Outcomes were as follows: prevalence of CPR-type diplopia in patients with ERM seen in retinal disease clinics, and whether or not clinical findings differed between patients with ERM and CPR-type diplopia vs patients with ERM without CPR-type diplopia. Results: Of the 31 patients with ERM seen in retinal disease clinics, 16 were women and 15 were men; the mean (SD) age was 69 (10) years. The prevalence of any diplopia was 23% (7 of 31; 95% CI, 10% to 41%), with CPR-type diplopia present in 16% (5 of 31; 95% CI, 5% to 34%). For analysis of associations, 12 of 56 patients (21%) had CPR-type diplopia and 37 (66%) had no diplopia. Seven of the 56 patients were excluded for other types of diplopia. Patients with CPR-type diplopia had better worse-eye visual acuity (mean difference, −0.23; 95% CI, −0.37 to −0.09 logMAR, P = .003), and more severe quantitative metamorphopsia (mean M-score difference 0.6; 95% CI, 0.05 to 1.1, P = .01) than patients without diplopia, but similar aniseikonia (Awaya new aniseikonia test; mean difference 0.6%; 95% CI, −2.9% to 4.0%, P = .33) and similar evidence of retinal misregistration (100% vs 73%; P = .09) by any test. Conclusions and Relevance: Our findings suggest that CPR-type diplopia is not uncommon in patients with ERM. On average, patients with CPR-type diplopia have better visual acuity and more metamorphopsia than those without CPR-type diplopia, but there is considerable individual variability. Aniseikonia and retinal misregistration are similar between patients with ERM associated with CPR-type diplopia and those without CPR-type diplopia. Retinal misregistration with coexistent metamorphopsia appears necessary but is not sufficient for CPR-type diplopia.