Purpose: Understanding how pupil size changes under different light conditions is important for refractive surgery, in contact lens fitting, as well as in the development of multifocal contact lenses. It is therefore of great value to have good measurement results and trustworthy methods. The accuracy and repeatability of the instruments used for these measurements are also critical.The purpose of this study was to investigate whether there was a potential relationship between the pupil diameter and the eye's refractive error with the use of the pupilometer incorporated within Sirius. A secondary purpose arose during the study, to evaluate the repeatability of the instrument Sirius. The null hypothesis of this study was; that pupil diameter is greater in myopes than hyperopes and emmetropes - that one would see a decrease in pupil diameter from myopes to emmetropes and also a decrease in pupil diameter from emmetropes to hyperopes. Method: There were 64 participants who took part in this study, aged between 20 to 36 years. Of these, three were excluded because they did not fit the inclusion criteria. The participants were divided into three different groups according to their spherical equivalent refractive errors: there were 26 myopes (range -7.75 D to -0.75 D), 17 emmetropes (range -0.50 D to +0.50 D), and 18 hyperopes (range + 0.75 D to + 5.75 D). Both eyes was measured. Pupil diameter was first measured in Sirius in a darkened room, where the computer was the only light source and the screen's brightness was dimmed. An objective refraction was done with the use of an autorefractor to get an estimated refractive value. Thereafter, retinoscopy was performed in a trial frame with a retinoscopy rack or loose trial lenses. The participants with higher astigmatism were also controlled with the use of the Jackson cross-cylinder. The pupil response was checked in all participants following pupil diameter measurements, to ensure that both eyes did not exhibit pupil defects. The result was analyzed with Excel and GraphPad Prism. Results: Since this study did not find any difference between the right and left eye, the data analysis was performed for right eye only. The mean and standard deviation (SD) of spherical equivalent power for myopes was -2.75 ±1.95 D, emmetropes -0.06 ±0.37 D and hyperopes +1.51 ±1.37 D. This study showed a weak trend between refractive error and pupil diameter, but no significant correlation between pupil diameter and the refractive state of the eye was evident, irrespective of lighting conditions; scotopic (p = 0.38), mesopic (p = 0.17) or photopic (p = 0.16). As expected, a clear decrease in pupil diameter with increased illumination intensity was found. A variance analysis (one-way, repeated measures ANOVA) was performed on the three different measurement in each illumination level, to confirm the repeatability of Sirius. The ICC values were 0.94 for scotopic, 0.87 for mesopic and 0.95 for photopic lighting conditions. Conclusuion: The study shows no significant correlation between pupil diameter and the refractive state of the eye over the range of -7.75 D to + 5.75 D. In this study, we also investigated the repeatability of the measurements values obtained with Sirius using the ICC; this showed that Sirius has a good repeatability in measuring pupil diameter in all three light levels.

Kan återkallning från långtidsminnet vara belönande i sig, oberoende av hur användbar informationen är? Intern motivation och metakognitiva bedömningar har tidigare undersökts i förhållande till igenkänning och återkallning. Studien ämnade att undersöka ifall korrekt återkallning av information instuderad närmare i tid kan leda till högre skattningar av konfidens och belåtenhet. Tidigare forskning kompletterades genom att undersöka effekten av kognitiv ansträngning på belåtenhet och konfidens. Eventuella relationer mellan återkallning och pupilldilatation undersöktes. Elva personer (M = 29 år) studerade 100 ord på swahili fördelade på fem tillfällen över en vecka. Därefter skulle samtliga ord återkallas i ett test med samtidig registrering av pupillstorlek. Resultaten indikerade att högre konfidens och lägre ansträngning kunde predicera högre belåtenhet vid korrekt återkallning. Genomsnittlig prestation var en bättre prediktor för belåtenhet än tid sedan instudering. Högre prestation predicerade högre belåtenhet vid korrekt återkallning. Resultaten indikerade en uppskattning för säkra minnen samt enkel och korrekt återkallning av dessa. Detta föreslås bero på ett samspel mellan instrumentella och belönande funktioner vid återkallning. Inga signifikanta relationer observerades mellan pupilldilatation och belåtenhet, konfidens eller ansträngning. Pupillförändring uppvisade svaga samband med samtliga men dessa hade inget prediktivt värde. / Can recollection from long-term memory in itself be rewarding, regardless of its usefulness? Internal motivation and metacognitive judgements have previously been explored in relation to recognition and recollection of memories. This study aimed to explore whether recollection of information studied closer in time can lead to higher ratings of confidence and satisfaction. Previous research was complemented by further investigating the effects of cognitive effort on satisfaction and confidence. Relationships between pupil dilation and recollection were also explored. Eleven people (M = 29 years) studied 100 words in swahili distributed over five sessions during one week. Recollection of the words was tested following the last study session. Pupil size was registered during the test. The results showed that higher confidence and lower cognitive effort could predict higher satisfaction at correct recollection. Average performance was a better predictor of satisfaction than time since a word was studied. Higher performance could predict higher satisfaction at correct recollection. The results indicated an appreciation of confidence in memories as well as easy and correct recollection. This may suggest an interplay between instrumental and rewarding functions during recollection. No significant relations were found between pupil dilation and satisfaction, confidence or cognitive effort. Pupil changes resulted in weak correlations with the aforementioned but were not predicted by any of them.