Ondategui-Parra, JC; Borras, M.; Peris, M. Elvira; Gascón, J.; Munllor, L.; de Castellarnau, A. European Academy of Optometry and Optics' Annual Conference Data de presentació: 2017-05-12 Presentació treball a congrés
Evaluation of binocular vision skills includes analysis of the accommodative and motor fusion systems. Motor fusion, often described clinically as fusional vergence, is analysed based on phoria direction and magnitude, convergence and divergence ranges and vergence facility. Vergence facility, defined as the number of cycles per minute (cpm) that a stimulus can be fused through alternating base-in (BI) and base-out (BO) prisms, attempts to capture the ability of the fusional vergence system to respond rapidly and accurately to changing vergence demands over time.
In clinics, vergence facility is a subjective method, while the patient has to indicate every time he is able to fusion one stimulus. However, the result of the test may have differences that depends on the observer (patient) and the examiner (optometrist).
To try to avoid this differences, the objective vergence facility is implemented in a prototype, a new fully autonomous and automated vision analyser (Eye and Vision Analyzer, EVA, DAVALOR, Spain) (Figure 1) that records eye movements while the patient watches a true-3D short video game.
This study was performed in two groups using two different methods. The subjective vergence facility (SVF) was performed in 54 young healthy subjects and the objective vergence facility (OVF) was performed in a subsample of 16 subjects. All of them didn’t have previous history of strabismus or amblyopia. The monocular visual acuity required at far and near distance was equal or better than 0.0 logMAR.
Inter-examiner and intra-observer repeatability for SVF
The mean age of the sample of 54 subjects was 21.5±1.5 years.
Intra-observer reliability: The mean difference was 2.06 cpm (p<0,001) and the Pearson Coefficient (PC) was 0.89 (p<0,001) (Figure 2).
Inter-examiner repeatability: The mean difference was 1.06 cpm (p=0.741) and the PC was 0.74 (p<0,001) (Figure 3).
Agreement between OVF and SVF
The mean age of the sample of 16 subjects was 22.1±2.7 years.
The mean OVF values were 9.5±11.3 cpm for C1, 14.1±9.3 cpm for C2 and 20.8±8.2 cpm for C3.
The mean SVF values was 18.3±1.9 cpm.
The best agreement was between SVF and OVF (C3) with a difference of 2.5±7.2 cpm (p=0.19) and PC of 0.58 (p=0.02) (Figure 4).
In ANOVA test there were not statistically significant differences (p=0.136) between all four methods.
The EVA prototype is a useful device to objectively measure VF. The OVF measured with EVA (6¿BI/6¿BO criteria) have a good agreement with the SVF (3¿BI/12¿BO criteria).
For SVF the inter-examiner results show that the agreement is better than the intra-observer results.
Further studies can improve the best prism combination to optimize the clinical pass/fail cut-off with EVA.
Ondategui-Parra, JC; Borras, M.; Peris, M. Elvira; Sánchez, Y.; Gómez, S.; Pujol, J. European Academy of Optometry and Optics' Annual Conference p. 144 Data de presentació: 2015-05-15 Presentació treball a congrés
Purpose: To determine the agreement between 4 different clinical methods for measuring stereoacuity in near vision: Randot (R), Titmus-Wirt (TW), TNO and Frisby (F) in two populations groups: children and university students.
Methods: Measurements were performed in healthy young subjects and children. None of the subjects had strabismus, amblyopia, ocular disease or previous history of eye surgery. Monocular best corrected visual acuity at far and near distances equal or better than 0.0 logMAR were required. The exams were performed in near vision (following the specifications of each method) under controlled conditions of illumination (L˜450 lux). The lower limits were determined only by the threshold measurement of each test. For the analysis the measures of stereopsis were transformed into a logarithmic scale. Finally, it was analyzed the agreement of the different stereoacuity results with the standards clinical pass/fail criteria for each one. (ESPECIFICAR)
Results: The mean age of the 55 university students was 21.5±1.56 years (Range: 19 to 23) and 9.2±0.45 (Range: 8 to 9) years for the 64 children. The range of stereoacuity results in both groups were 20”-70” for R, 40”-70” for TW, 15”-480” for TNO and 20”-85” for F. In young subjects and children the differences between the values converted into a log scale were not statistically significant for any test (p>0.05). Applying the Bland & Altman analysis, Confidence Interval (at 95%) more reduced were found comparing the R vs TW test and R vs F test, in both groups. To apply the pass/fail criteria it was used the clinical recommendations of each test for each test. In both groups the concordance was =95% in TW vs TNO tests and TW vs F tests. In addition, regarding children, it was obtained a high concordance TNO vs F tests. The lower agreement in the group of adults was between the R vs F tests (74.5%) and for children between the R vs TNO tests (78%).
Conclusion: Studying the correlation between clinical tests of stereopsis is a complex task because (1) few tests allow the assessment of stereoacuity threshold due to the lower range of the results is imposed by the measurement tool; (2) the measurement scales are sometimes geometric progressions (TNO and F), or random measurement scales (R and TW), that difficult the analysis of the results.
Analyzing the agreement through the cut-off clinically recomended for each test, they showed a high agreement in all cases. The pair of stereoacuity tests that presented a higher agreement was TW and TNO tests in both groups and TNO and F tests in the children group.