Aberāciju ietekme uz spēju atšķirt dihoptiskus attēlus
Date
2010
Authors
Kuibida, Marija
Journal Title
Journal ISSN
Volume Title
Publisher
Latvijas Universitāte
Abstract
Bakalaura darbs ir uzrakstīts latviešu valodā uz 43 lappusēm. Tas satur 27 zīmējumus, 7 tabulas, 2 pielikumus un 50 atsauces uz literatūras avotiem.
Atslēgas vārdi: aberācija, dihoptiskie attēli, atšķiršanas slieksnis, konstantu stimulu metode, RMS vērtība.
Darba mērķis: Noskaidrot, kāda ir RMS vērtība katram aberāciju veidam, pie kuras subjekts spēj pamanīt attēla atšķirības.
Subjekti: Eksperimentā piedalījās 15 subjekti no 18 līdz 21 gada vecumam (vidējais vecums 20 gadi), 2 subjektiem bija miopijas korekcija, subjektu vidējais starpzīlīšu attālums ir 62,2 mm. Eksperimenta laikā 10 no 15 subjektiem bija nepieciešama prizmatiskā korekcija, lai varētu saplūdināt dihoptiskus attēlus.
Metode: Pirms eksperimenta uzsākšanas, subjekts pavadīja vismaz 15 min tumsā, lai adaptētos tumsas apstākļiem. RMS slieksnis tika mērīts ar konstantu stimulu metodes palīdzību. Ar PMT datorprogrammas palīdzību tika mainīts aberācijas veids un apjoms tādā veidā mainot kreisās acs attēla kvalitāti. Subjektam bija jāziņo, vai viņš redz vai neredz izmaiņas attēla kvalitātē. Eksperiments tika atkārtots 10 reizes katram subjektam.
Rezultāti un to analīze: Viena subjekta dati tika izslēgti no datu analīzes, jo subjekts neadekvāti atbildēja uz stimulu. Eksperimenta laikā iegūtajiem rezultātiem tika zīmētas psihometriskās līknes. Slieksnis tika ņemts pie 50% stimula uztveršanas reizēm. Katram aberācijas veidam ir atrastas RMS sliekšņa vērtības, pie kurām subjekts sāk pamanīt attēla atšķirības. Astigmātismam RMS sliekšņa vērtība ir 0.154 ± 0,01 Ām, Komai 0.126 ± 0,008 Ām, Trīslapiņu aberācijai 0.105 ± 0,007 Ām un Sfēriskai aberācijai 0.204 ± 0,014 Ām. Starp visu aberācijas veidu RMS sliekšņa vidējām vērtībām, izņemot komu un trīslapiņu aberāciju, ir būtiska atšķirība (p << 0,05).
Secinājumi: RMS sliekšņa vērtības dažādiem aberācijas veidiem ir dažādas. RMS sliekšņa vērtību analīze parāda, ka starp četriem aberāciju veidiem (astigmātisms, koma, trīslapiņu aberācija, sfēriska aberācija) trīslapiņu aberācijai ir vismazākā RMS sliekšņa vērtība, bet vislielākā ir sfēriskai aberācijai.
Backelor work is written in latvian on 43 pages. It contains 27 images, 7 tables, 2 appendices and 50 sources of literature. Key Words: aberration, dichoptic images, discrimination threshold, the method of constant stimuli, RMS value. Purpose: The aim of this study was to evaluate RMS threshold levels of different aberration types change that subjects is able to detect. Subjects: There were 15 subjects involved in this study between the ages of 18 and 21 (the mean age was 20). There were 2 miopic subjects. Subject’s mean interpupillar distance was 62,2 mm. In the process of this study, 10 subjects worn their prismatic correction. It was necessary to fuse the dichoptic stimuli in the unit perception. Methods: Before experiment, each subject sat in the dark room at least 15 min, so the subject was adapted to the dark. RMS threshold was measured with the method of constant stimuli. Aberration’s type and amount was changed with computer software program PMT. The subject’s left eye’s image quality was changed during experiment. The subject was needed to say if he or she sees the changes in the image quality. 10 trials were made at each aberration setting for each subject. Results: We didn’t use one subject’s outcomes, because she guessed about the changes in the image quality. The outcomes was plotted as a psychometric function for each aberration type for eacs subject. Threshold was taken as the point where the subject detects the stimulus 50% of the time. For astigmatism RMS threshold value is 0.154 ± 0,01 Ām, for coma 0.126 ± 0,008 Ām, trefoil 0.105 ± 0,007 Ām and spherical aberration 0.204 ± 0,014 Ām. Conclusions: RMS threshold value is different between different aberration types. Trefoil has the lowest threshold value, but spherical aberration has the highest RMS threshold value.
Backelor work is written in latvian on 43 pages. It contains 27 images, 7 tables, 2 appendices and 50 sources of literature. Key Words: aberration, dichoptic images, discrimination threshold, the method of constant stimuli, RMS value. Purpose: The aim of this study was to evaluate RMS threshold levels of different aberration types change that subjects is able to detect. Subjects: There were 15 subjects involved in this study between the ages of 18 and 21 (the mean age was 20). There were 2 miopic subjects. Subject’s mean interpupillar distance was 62,2 mm. In the process of this study, 10 subjects worn their prismatic correction. It was necessary to fuse the dichoptic stimuli in the unit perception. Methods: Before experiment, each subject sat in the dark room at least 15 min, so the subject was adapted to the dark. RMS threshold was measured with the method of constant stimuli. Aberration’s type and amount was changed with computer software program PMT. The subject’s left eye’s image quality was changed during experiment. The subject was needed to say if he or she sees the changes in the image quality. 10 trials were made at each aberration setting for each subject. Results: We didn’t use one subject’s outcomes, because she guessed about the changes in the image quality. The outcomes was plotted as a psychometric function for each aberration type for eacs subject. Threshold was taken as the point where the subject detects the stimulus 50% of the time. For astigmatism RMS threshold value is 0.154 ± 0,01 Ām, for coma 0.126 ± 0,008 Ām, trefoil 0.105 ± 0,007 Ām and spherical aberration 0.204 ± 0,014 Ām. Conclusions: RMS threshold value is different between different aberration types. Trefoil has the lowest threshold value, but spherical aberration has the highest RMS threshold value.
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