Academic literature on the topic 'Modified Thorington'

Background/Aims Smartphone use has become an indispensable part of our daily life. The handy design and powerful processor allow smartphone users to perform diversified tasks even when walking. This study aimed to investigate and compare the optical aftereffect and vergence adaptation of using a smartphone while walking and sitting. Methods Twenty-nine young healthy adults (aged 19 to 24 years old) with normal binocular and accommodative functions were recruited. Participants were asked to watch a movie for 30 minutes using a smartphone while either walking on a treadmill or sitting on a chair. Corneal aberrations and near heterophoria were measured before and after smartphone use by a corneal topographer and modified Thorington heterophoria test, respectively. Results Using the smartphone while walking induced a change in corneal H/V astigmatism, becoming 0.11±0.03 μm less negative (two-way ANOVA repeated measures, Bonferroni post-hoc test, p = 0.001). This optical aftereffect was significantly higher than after smartphone use while sitting by 0.10±0.03 μm (paired t-test, p = 0.003). Although smartphone use did not result in a significant change in near heterophoria (Bonferroni post-hoc test, p > 0.15), the vergence adaptation showed relatively more eso- or less exo-deviation by 0.79±0.36Δ in the walking than the sitting condition (paired t-test, p = 0.037). Conclusions Eyecare practitioners should be cautious of the potential optical after effect and vergence adaptation after prolonged smartphone usage.

Background: While a number of previous studies have investigated the repeatability of techniques designed to measure heterophoria, there have been few studies of their validity. Accordingly, the present study examined the ability of 3 standard techniques; Von Graefe (VG), Maddox Rod (MR) and Modified Thorington (MT) tests to quantify a known change in heterophoria. Methods:The study was performed on 30 young subjects using each of the 3 procedures listed above. Near (40 cm) heterophoria was quantified both without and with an additional base-out prism. Five possible values were available, namely 2, 4, 6, 8 and 9Δ. After a period of 24 hours, the heterophoria measurement was repeated using the same technique with one of these prisms added to the refractive correction. Results:The mean heterophoria value measured before the introduction of prism using the VG procedure was significantly more exophoric than the findings obtained using the other 2 techniques (p = 0.035). No significant difference was observed between the measured and predicted change in heterophoria following the introduction of the prism for the VG and MT procedures, but a significant difference was found with the MR technique (p0.001). Conclusions:The ability to measure a known change in oculomotor deviation was significantly poorer with the MR technique, when compared with the VG and MT procedures. Given that the mean pre-prism measurement was significantly more exophoric when using the VG procedure, we recommend that MT be adopted as the technique of choice for the subjective measurement of oculomotor deviations in the clinical setting

Background: Proximal vergence is defined as a vergence eye movement subtype driven by an “awareness of nearness”. The purpose of this experiment was to compare values of proximal vergence calculated with and without measures of accommodation to assess the clinical utility of each measurement method. Methods: Thirteen participants between the ages of 22 and 37 (mean = 28.5 ± 4.5 years) were enrolled. The distance and near heterophoria were measured using the Modified Thorington technique. The near heterophoria was measured under three randomized viewing conditions (no lenses, +1.00D lenses, +2.50D lenses). Refractive error was measured with an autorefractor. Proximal vergence was calculated as the difference in calculated (far-near) and gradient (+1.00) stimulus AC/A ratios (stimulus AC/A differencing method), the difference in calculated and gradient response AC/A ratios (response AC/A differencing method), and the change in vergence from distance to near with the +2.50D lenses (uncorrected +2.50D method). This latter value was also corrected for any active accommodation with +2.50D lenses (corrected +2.50D method). Results: The mean proximal vergence values (Δ) were 7.82 ± 5.98 (stimulus AC/A differencing method), 8.29 ± 3.30 (response AC/A differencing method), 6.23 ± 3.52 (uncorrected +2.50D method), and 5.13 ± 2.98 (corrected +2.50D method). The only comparison that showed both a significant correlation (p<0.05) and a non-significant difference from the paired t-test (p>0.05) was that between the stimulus AC/A differencing method and the uncorrected +2.50D method. Conclusions: When response accommodation was accounted for, differences occurred in the mean proximal values obtained with the various methods. The means of the methods most likely to be used clinically (stimulus AC/A differencing method and uncorrected +2.50D method) were similar, although some individuals demonstrated significant differences between these methods.

Bakgrund: Heteroforier är något man kan se hos de allra flesta personer. Det finns inga specifika symtom för forier, utan symtomen kan likväl vara tecken på andra problem. Dessa ospecifika symtom kan dock vara tecken på just forier, och med anledning av detta kan det finnas ett värde i att mäta forierna hos patienter som uppvisar symtom. I syfte att mäta forier kvarstår dock frågan, vilken adekvat metod bör användas? Ger alla metoder samma resultat, om inte på vilka sätt skiljer de sig åt? Framkommer någon skillnad i tillförlitlighet metoderna emellan? Syfte: Studiens syfte var att utvärdera repeterbarheten hos tre utvalda forimätningsmetoder samt jämföra hur resultaten av de olika metoderna förhåller sig till varandra. Metoder: I studien jämfördes metoderna Modifierad Thorington (MT), Schober (SCH) och von Graefe (VG) på trettio försökspersoner. Samtliga mätningar utfördes i samma ordningsföljd och inleddes med Modifierad Thorington följt av Schober och avslutades med von Graefe. Varje metod mättes tre gånger för att kunna utvärdera repeterbarheten. I studien mättes enbart avståndsforier. Resultat: Modifierad Thorington sattes som "guldstandard" varpå de övriga metoderna jämförts med den. Vid horisontella forier ≤1,0Δ gav samtliga metoder jämförbara resultat. Vid exoforier visade Modifierad Thorington högst forier, medan Schober visade lägst. Endast en person hade en esofori ≥1,0Δ med Modifierad Thorington därför kunde inga jämförelser göras mellan resultaten av de olika metoderna vid esofori. Slutsats: Modifierad Thorington, Schober’s test och von Graefes metod för forimätning visade alla jämförbara resultat bortsett från mätningar vid högre forier. SCH visade den bästa repeterbarheten baserat på den lägsta standardavvikelsen (0,19Δ) följt av MT (0,45Δ) och VG (0,47Δ). Genom att jämföra mätningarnas repeterbarhet med korrelationskoffecienten för varje metod (T1 vs T2, and T1 vs T3) kunde en något högre korrelation ses för MT (r=0.96, 0,96) än SCH (r=0,95, 0,93). Även von Graefe visade bra korrelation mellan mätningarna (r=0,90, 0,93), trots att värdena var något lägre än för MT och SCH.