Thesis (Ph. D.)--University of Toronto, 2004. / Adviser: John A. Ross. Incluedes bibliographical references.

Rotator cuff disorders encompass a range of impairments from tendinopathy to partialor full-thickness rotator cuff tears, and represent the largest subgroup of shoulder pain. Rotator cuff tears, most of which are atraumatic, are common in adults with shoulder pain and are strongly associated with increasing age. Conservative treatment including physiotherapy is the first-line treatment, but some patients do not respond, and ultimately require surgery. Early predictions of response could allow individuals’ care pathways to be optimised, preventing unnecessary delays and suffering and benefiting patients and healthcare providers alike. My primary aim was to develop a prognostic model for the outcome of physiotherapy in adults with painful atraumatic partial-thickness tears (PTTs) of the rotator cuff. This was addressed by a prospective prognostic model study. The study was underpinned by a systematic review of prognostic models in adults undergoing physiotherapy for painful rotator cuff disorders and was further informed and complemented by the following work: the development and validation of the physiotherapy protocol for the prognostic study; the identification, selection and definition of the candidate prognostic factors for the prognostic study; the estimation of the Minimal Important Difference (MID) of the study’s primary outcome measure (the Western Ontario Rotator Cuff Index, WORC); and an exploratory responder analysis of the WORC outcome scores. The prognostic systematic review, prognostic study, MID analysis and responder analysis are original contributions to knowledge. The prognostic systematic review revealed important methodological deficiencies in the five included studies, and no clinically usable model. No study addressed a distinct PTT population. The process of identifying factors for my own prognostic model study revealed a lack of knowledge about the prognostic relevance of factors. All of the candidate models I explored in my prognostic study (n sample = 65, n analysed = 61) had low performance and precision. The estimated MID of the WORC was -300. The responder analysis resulted in different proportions of responders to treatment depending on the responder definition. My results highlight the difficulties involved in predicting outcomes in the field of shoulder pain and rotator cuff disorders, and the need for methodologically sound prognosis research.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / This investigation assessed the diagnostic accuracy of thin-slice (1mm) axial Magnetic Resonance Imaging (MRI) in the detection and classification of meniscal tears. Meniscal injuries are a common reason for knee pain and the use of MRI has become standard in their assessment. However, the classification of tears and not merely the detection of lesions has become increasingly important to surgeons in deciding between surgery and conservative management. There is a growing body of literature examining the utility of axial MR images in aiding radiologists to more accurately describe and classify morphological characteristics of meniscus tears. However, the thick- slice (4-5mm) axial sequences utilized at many institutions typically only produce 1-2 images on which the menisci can be visualized, which does not provide the required detail to accurately describe the morphological characteristics of meniscal lesions. This study adds to the growing body of literature examining the diagnostic capabilities of MRI with TSAi to accurately describe meniscal tear morphologies. Imaging reports from 107 patients with clinically suspected meniscus injuries who underwent MRI with thin-slice axial imaging were compared to arthroscopic findings using receiver operating characteris (ROC) analysis to assess the diagnostic accuracy of MRI with thin- slice axial imaging (TSAi). The sensitivity and specificity of MRI with TSAi for meniscal tear detection were found to be 91% and 37.5% respectively. Furthermore, MRI with TSAi was highly specific for bucket handle (98.5%) and root ligament tears (94.1%). The findings of our investigation indicate that MRI with TSAi may assist surgeons in determining the need for operative versus conservative management. MRI with TSAi may be particularly helpful in the case of root tears, which were not as readily identified with traditional MRI techniques and often require surgical intervention due to morbidity associated with unrepaired root tears.

This body of work encompasses two studies: the collection of canine tears via a novel polyester<br />rod and the comparison of VEGF-A concentrations in tears from dogs with normal and<br />vascularized corneas. The first study used polyester rods for tear collection in dogs. Fluid volume and VEGF recovery characteristics, as well as potential binding of VEGF to the rod, were determined. Tears were harvested from normal dogs using rods and glass capillary tubes. Tears were assayed for tear film VEGF using a commercial canine VEGF sandwich ELISA kit. Dilutions of VEGF standard were wicked into the rods or drawn into capillary tubes, eluted, and assayed. Percent volume recovery is adequate for polyester rods as is percent VEGF recovery. VEGF is detectable in normal canine tears.The second study harvested tear samples from eyes of dogs with vascularizing corneal disease, as well as the contralateral unaffected eye of unilaterally diseased dogs, and normal dogs. Vascularization scores were assigned to diseased eyes and tear film VEGF concentration was assayed as above. Mean tear film VEGF concentration of diseased eyes did not differ from control eyes, and was not correlated with disease process, extent of vascularization, or other parameters. Tear film VEGF in unaffected eyes was significantly higher than control and vascularized eyes. Canine tear film VEGF exceeds biologically active concentrations, but does not correlate with state of corneal vascularization. VEGF-related control of corneal vascularization may be mediated by other proangiogenic factors. / Master of Science

A finite element model of a fracture test specimen is developed using the STAGS computer code (STructural Analysis of General Shells). The test specimen was an internally pressurized, aluminum cylindrical shell reinforced with two externally bonded aluminum tear straps around its circumference. The shell contained an initial, axial through-crack centered between the straps. The crack propagated slowly in the axial direction as the pressure increased above a certain value until a maximum pressure was attained, and then the crack propagated dynamically. The tear straps sufficiently toughened the shell such that the dynamic crack path bifurcated near the edges of the straps. The bifurcated crack branches ran circumferentially, parallel to the straps causing the shell wall to flap open. The STAGS analysis for the static equilibrium configurations of the fractured shell include geometric nonlinearity and elastic-plastic material behavior. The crack tip opening angle (CTOA) is used in the criterion for ductile crack growth, and the critical value of the CTOA is determined by correlating the STAGS predictions of the stable portion of the crack growth curve (internal pressure versus half crack length) to the test. With the employment of a new STAGS algorithm, the complete axial crack growth curve, including both the stable and unstable portions, through the tear strap is obtained. The complete axial crack growth curve indicates that crack growth through the strap is unlikely. STAGS models with long cracks which bifurcate at various half crack lengths are developed to assess the location of crack bifurcation. Three different stress based crack turning criteria are investigated from the axial crack growth results as a second method for assessing a location of bifurcation. The bifurcation analyses and stress based turning criteria corroborate the experimentally measured bifurcation point. A parametric study is then conducted to determine the influence of tear strap thickness and width on the location of crack bifurcation. / Master of Science

The purpose of this study was to determine the effects of three medical treatments, topical oxytetracycline, topical prednisolone acetate, and systemic flunixin meglumine, on the activity of two proteinases, matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), in equine tear film. The study design consisted of twelve ophthalmically normal horses separated into three groups of four in a cross-over study design. Each group was treated for 5 days with flunixin meglumine (500mg IM bid), topical 1% prednisolone acetate (0.2ml tid), or topical oxytetracycline (0.2ml tid), followed by a 9-day washout period. All topical medications were applied to the left eye and the right eye was treated with a placebo. Tears were collected before the first treatment on day one and the morning following the last treatment on day 5. Tear film proteinase activity was measured using gelatin zymography and measurements of optical density. Statistical analysis of the difference between the treated and untreated eyes and the eyes before and after treatment was performed using mixed effects model for ANOVA. When eyes were compared after treatment, there was no significant difference between treated and placebo eyes for MMP-2 or MMP-9 for any of the treatments. When post-treated eyes were compared to pre-treated eyes, there was a significant decrease in MMP-2 activity in the left eye of horses treated with flunixin meglumine (P=0.0259). There were no differences in MMP-2 and MMP-9 activity for the other treatments. In conclusion, topical 1% prednisolone acetate and topical oxytetracycline did not significantly change MMP-2 or MMP-9 activity in normal equine tear film. Systemic flunixin meglumine had an inhibitory, but questionable, effect on MMP-2 activity in normal equine tear film. This project was funded by Patricia Bonsall Stuart Award for Equine Research. / Master of Science

Trečdalis gyventojų kenčia dėl pavargusių ir sausų akių sindromo (Pečeliūnienė, 2006). Juos vargina jausmas, lyg į akis būtų pripilta smėlio ar žvyro, akis gali parausti arba atsiranda būdingas svetimkūnio bei diegimo, raižymo pojūtis, šviesos baimė. Rytais, tik atsimerkus, gali būti jaučiamas neilgalaikis aštrus skausmas ar padidėjęs ašarojimas bei akių nuovargis, matymo pablogėjimas, kontaktinių lęšių netoleravimas. Pusė patiriančiųjų pavargusių akių simptomus jų visai negydo. Nesiėmus reikiamų priemonių, tokiems žmonėms vėliau diagnozuojamas sausų akių sindromas (SAS). Ypač dažnai sausumas vargina pacientus, dėvinčius kontaktinius lęšius – ašarų turi pakakti dar ir lęšiui sudrėkinti. / One third of people suffer from tired and dry eye syndrome (Pečeliūnienė, 2006). They weary a feeling of eye full of sand or gravel, ache and cutting, fair of light, an eye can get red. In the mornings when eyes are just opened, there can be a short period of sharp ache or increased tearing and also eye tiredness, vision deterioration, intolerance of contact lenses. A half of people who suffer from eye tiredness, do not treat them at all. When taking no measures, a dry eye syndrome is later diagnosed (SAS). This very often appear to people with contact lenses - tear drops must be also enough for irrigating the lenses.

Thesis (M.S.P.H.)--Uniformed Services University of the Health Sciences, 2006 / Typescript (photocopy)

The overarching theme of the thesis was to investigate the association between smart device use and computer vision syndrome. The initial study designed and developed the Open Field Tear film Analyser (OFTA) enabling a continuous, real-time assessment of the tear film and blink characteristics during smart device use. The monocular OFTA prototype was validated and showed good intra- and inter-observer repeatability relative to the Oculus Keratograph 5M and Bausch and Lomb one position keratometer. Subsequently, tear osmolarity following engagement with reading and gaming tasks on smart device and paper platforms was investigated. Discrete measures of osmolarity pre- and post-engagement with the tasks were obtained with the TearLab osmometer; osmolarity values differed between platforms when participants were engaged in a gaming task but no such difference was observed with the reading task. In addition, the influence of repeated measurements on tear osmolarity was also explored. To simulate the habitual binocular viewing conditions normally associated with smart device use, the binocular OFTA was developed. The device was used to assess the tear film and blink characteristics whilst engaging with reading and gaming tasks on smart device and paper platforms. The results revealed differences in blink characteristics and non-invasive tear break up time between the different platforms and tasks assessed. In addition, the thesis also reports on an investigation examining the real-time accommodative response to various targets displayed on smart devices using an open-field autorefractor with a Badal lens system adaptation. The results showed that accommodative latency, accommodative lag, mean velocity of accommodation, speed of disaccommodation and mean velocity of disaccommodation varied across the different platforms. Through the use of validated subjective questionnaires and smartphone apps, the relationship between duration of smartphone use and symptoms of dry eye were examined. The findings of this study demonstrated that longer duration of smartphone and personal computer use were associated with higher risk of dry eyes as indicated by subjective questionnaire outcomes.

The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface, where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. A dual interferometer system for measuring the dynamic corneal topography is designed, built, verified, and qualified by testing on human subjects. The system consists of two coaligned simultaneous phase-shifting polarization-splitting Twyman-Green interferometers. The primary interferometer measures the surface of the tear film while the secondary interferometer tracks the absolute position of the cornea, which provides enough information to reconstruct the absolute shape of the cornea. The results are high-resolution and high-accuracy surface topography measurements of the in vivo tear film and cornea that are captured at standard camera frame rates. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)