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- Scanpath (1)
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- contact lens-induced papillary conjuctivitis CLPC (1)
- follicular-like conjunctivitis associated with siliconhydrogels FoCoSi (1)
- giant papillary conjuctivitis GPC (1)
Institute
Purpose
Automated scanpath comparison metrics should deliver an objective method to
evaluate the similarity of scanpaths. The aim of this thesis is an evaluation of
seven existing scanpath comparison metrics in static and dynamic tasks in order
to provide a guidline that helps to decide which algorithm has to be chosen for a
special kind of task.
Methods
The applicability of the algorithms for a static, visual search task and a dynamic,
interactive video game task as well as their constraints and limitations were tested.
Therefore, binocular gaze data were recorded by using the eye tracking system The
Eye Tribe (The Eye Tribe ApS, Copenhagen/ Denmark). Objective task performance
measures from 21 subjects were used in order to create scanpath groupings
for which a relevant effect of dissimilarity was to be expected. Objective task performance
measures such as task performance time were statistically evaluated and
compared to the results gained by the comparison metrics.
Results
Four of the algorithms being used successfully identified differences for static and
dynamic tasks: MultiMatch, iComp, SubsMatch and the Hidden Markov Model.
ScanMatch was very sensitive for the static task but not applicable to the dynamic
task whereas FuncSim was suitable for dynamic but not for static tasks. Eyenalysis
failed to detect any effect.
Conclusion
The applicability of scanpath comparison metrics depends on the state of the task,
respectively on the kind of experimental set up. In future, the application area for
eye tracking will expand and an improvement of automated scanpath comparison
metrics is therefore required.
Purpose: Although the frequency in which practitioners are fitting scleral
contact lenses is increasing, the recommendation for proper tear layer depth
(thickness) varies amongst experts. The main goal of this paper is to clinically
verify the effect of varying tear layer depths on induced corneal edema during
lens wear.
Methods: Ten subjects with healthy eyes were fitted with scleral lenses on their
right eye. Each of them was fit with two different lenses: one with an apical
clearance of 200 μm and another with an apical clearance of 600 μm. They wore
the lenses for 8 hours on two different days, with at least a one week wash-out
period. Lenses were applied at 8 a.m. on each of the testing days. Pachymetry
measurements were taken one day prior to lens wear at 4 p.m., on the day of
wear prior to lens application, and after removal of the lenses at 4 p.m.
Measurements were collected using both the Pentacam® HR Corneal
Tomographer, as well as the Visante Anterior Segment Optical Coherence
Tomographer (OCT). The apical clearance was measured using the
Visante OCT at two intervals during the test day: immediately after application of
the lens and immediately prior to the removal of the lens.
Results: In this study, there was found to be no significant difference in corneal
edematous response during lens wear between the two test groups. The study
shows that the eyes with the lenses have a statistically significantly thicker
cornea compared to the non-lens-wearing eye after wearing either lens for 8
hours, lying within clinically and physiologically acceptable limits.
Conclusion: Our clinical results do not correlate with current theoretical
calculations, which predict a greater amount of corneal swelling with increasing
tear layer thickness. It has to be evaluated if the effect on corneal edema
changes with longer wearing periods, larger samples or other influences.
Key words: scleral (contact) lens, corneal edema, pachymetry, tear layer
thickness, vaulting, apical clearance
Abstract
1.1 Purpose
The purpose of this study is to prescribe follicular-like conjunctivitis associated with Siliconhydrogels
(FoCoSi) in silicone hydrogel contact lens wearers as a novel subtype of
the well prescribed contact lens induced papillary conjunctivitis (CLPC).
1.2 Methods
1211 patients who wore silicon hydrogels were included in this prospective, nonrandomised,
single center study. Subjective symptoms and clinical signs were evaluated
for daily wear (DW) and continuous wear (CW) populations for several (Lotrafilcon A,
Lotrafilcon B, Senofilcon A, Galyfilcon A) silicon hydrogel lens types. CCLRU and other
specifically developed grading scale were utilized for evaluation. Grading of 2 and above
was rated as clinically significant. Statistical evaluation was performed for eyes rather
than subjects.
1.3 Results
The clinical presentation of FoCoSi could be confirmed and showed an incidence of
3.8%. Lotrafilcon A followed by Senofilcon A on a CW modality presented, with a risk
ratio of 2.49 and 1.53 respectively, the highest affinity for developing FoCoSi. Fluorescein
positive spots showed the closest correlation with subjective symptoms reported
by patients and divided FoCoSi into an active and dormant form. Besides Protein, Lipid
deposition on the contact lens surface and air pollution like Ozone or fine and ultrafine
particles seems to be important factors in developing FoCoSi, whereas mechanical irritation
played a minor role.
1.4 Conclusion
FoCoSi is a novel and relevant subtype of CLPC. Further studies should be performed
to validate these findings and clear up several questions about the aetiology of FoCoSi
and CLPC.
Keywords: Giant papillary conjunctivitis (GPC), contact lens-induced papillary conjunctivitis
(CLPC), follicular-like conjunctivitis associated with siliconhydrogels (FoCoSi)
Purpose
The purpose of this study was to evaluate the validity of the iPad Aniseikonia Test for
measurement size lens-induced aniseikonia. The iPad Aniseikonia Test is a new
computer-based test designed for measuring aniseikonia in vertical direction. The iPad
Test uses red-green anaglyphs.
Methods
Aniseikonia was induced in 21 subjects by means of afocal size lenses. Resulting
aniseikonia was measured in vertical direction by the iPad Aniseikonia Test. The
measurement was performed in dark condition with appropriate correction of refractive
error. All subject were patients with normal vision with no anisometropia or other
ocular problem.
Results:
Afocal size lenses of known magnification were used to induce aniseikonia. 5
measurements were taken in each subject, ranging from zero to 7 % magnification.
When using the regression analysis, the slope of the fitted line significantly differs from
1. The average slope of regression line is 0,58.
Conclusions:
Only moderate accuracy was found for tested target size and orientation. In all cases the
iPad Aniseikonia Test underestimates the level of aniseikonia. However for gross
assessment of anisometropia in clinical practice it could be successfully used. Further
study with different target size should be addressed.
Purpose
The purpose of this study was to investigate the correlation of measured visual acuity
(VA) both static and dynamic obtained with static and dynamic measuring tests, as well
as, response time to visual stimulus and analysis of its influence on dynamic visual
acuity. The aim was to compare the results gathered for the three age groups and
analyze the possible differences.
Methods
The test groups consisted of 75 subjects between 10 and 60 years old, categorized in
three age groups. The measurements of static and dynamic visual acuity and reaction
time were conducted. The set of nine tests (five with radial magnification speed and four
simulating driving condition at 72 km/h and 130 km/h) was designed in order to measure
dynamic visual acuity and the set of two tests for reaction time measurement.
Results
Compared to static visual acuity in both tests, the results obtained with measurements
of dynamic visual acuity resulted in lower values depending on Landolt ring size and
magnification speed of animation. In average, the dynamic visual acuities in tests with
different magnification speeds were lower than static by 0.4 visual acuity units, or 31%
and the average of dynamic visual acuity after subtracting motoric component (reaction
time) was for 0.2 visual acuity worse than static or 15%. In the second test simulating
driving conditions at 72 km/h the average drop in dynamic visual acuity was 33% while
at 130 km/h average drop for younger and middle age groups was 37% and for older
group was 44% and after subtracting motor component values for 72 km/h speed
simulation average drop in visual acuity values was 23% for all three groups; for 130
km/h speed simulation younger and middle aged group average drop of visual acuity
was 20% and with older group it was 24%.
Conclusion
The tests used in this study were simple and fast and revealed significant difference
between static and dynamic visual acuity and influence of reaction time on dynamic
Nataša Vujko Muždalo Abstract
2
visual acuity values. It is hoped that this thesis will be a positive contribution in testing
and training of dynamic visual and sensory response skill with drivers, sportsmen and
people with visual-motor dysfunction.
Keywords: Dynamic visual acuity (DVA), static visual acuity (SVA), reaction time (RT),
motoric component, dynamic visual acuity test, reaction time test, radial increase in size
A good stereopsis (depth perception) is needed in everyday life, regardless whether a person is a professional driver or chef. Good estimation of distance, and of what is further and what closer, could mean the difference between a crushed and a whole car or between a bloody and a healthy finger. The main theme of this Master thesis is detect and quantify major factors in depth perception. Do the younger estimate the depth better than the older; do they have better depth perception with greater or smaller pupil distance; does depth perception depend on gender; what happens with stereopsis when vision is fogged by +0,5 and +1,0 D? These are the questions dealt with in this Master thesis.
To answer these questions measurements were made on 51 subjects (mean age 45,0 +/- 13,32 years) of whom 25 were women, mean age 45,5 +/-13,55 years (12 with PD<62 mm, mean and 13 with PD>66 mm) and 26 men, mean age 44,4 +/- 13,34 years (13 with PD<62 mm and, 13 with PD >66 mm). Each of these four groups was further divided by age (one in range 20 to 35 years and second in range 50 to 65 years).
The measurements were made with a few assumptions. The first assumption was that stereopsis is in direct correlation with visual acuity, the second assumption was that persons with bigger interpupillar distance have better stereopsis, and the third assumption was that with age the stereopsis ability decreases.
The measurements were done with modified Frisby–Davis test expanded from four geometrical shapes to twenty-five circles. The stereopsis was measured with full refractive correction at 4,5 and 3,0 meters. Later, stereopsis was measured with fogging with +0,5 and +1,0 D at the 4,5 and 3,0 meter distances.
Statistically there is no correlation (or very weak) between stereopsis and the visual acuity for whole group of 51 test persons, but if only young test persons are taken in consideration, the correlation becomes significant, r(20)=0,566, p=0,009 at 4,5 m and r(20)=0,456, p=0,043 at 3,0 m and that matches the assumption. Stereopsis is in no or weak positive correlation with pupil distance r(51)=0,059, p=0,679, which is in total contrast to the assumption. Stereopsis is in positive correlation with age at 4,5 meters measuring distance, r(51)=0,371, p=0,007, which corresponds to assumption. In addition, stereopsis is better in females than in males by 32,5%.
Based on the results it can be concluded that the stereopsis is in negative correlation with age, in positive correlation with visual acuity, females have better stereopsis than males and statistically, the correlation between stereopsis and pupil distance (PD) has not been proved. The most important conclusion is that the decreased visual acuity brings significant fall of stereopsis. A deficit in refraction of -0,50 D decreases stereo acuity by about 90% (nearly 2x) and a deficit of -1,0 D decreases stereo acuity by about 220% (about 3x).
Keywords: Stereopsis, stereo acuity, depth perception, pupil distance (PD), visual acuity (VA).