Thesis (M.Sc. (Optometry)) --University of Limpopo (Turfloop Campus), 2010 / Human Immunodeficiency Virus (HIV) and the associated Acquired Immunodeficiency Syndrome (AIDS) are major public health concerns worldwide and present socioeconomic burden to many governments. To combat this scourge, a deep knowledge about this pandemic is required as one of the preventive methods. Also, the knowledge can serve as a tool to help those who are infected. HIV/AIDS is common among adolescents; therefore, one of the aims of this study is to establish the knowledge of basics of HIV/AIDS among high school learners in the Capricorn district of the Limpopo Province, South Africa.HIV/AIDS also affects the eye; identification of the ocular problem can sometimes help with the diagnosis of HIV/AIDS the condition. Therefore may have both sight and life-saving implications. The school curriculum and HIV/ AIDS awareness campaigns in South Africa do not include basic knowledge of the effects of HIV/AIDS on the eye; therefore an additional aim of this study was to establish the basic knowledge of the effects of HIV/AIDS on the eye among the participants, so that an informed recommendation can be made for the inclusion of the eye component in the awareness campaign and school curriculum. Methodology Following relevant research and ethics approval of the proposal, relevant permissions were obtained before the study commenced. A quantitative survey design was used for the study. Stratified random sampling method was used to select high schools and students that took part in the research. The participants were learners from 18 selected high schools in the Capricorn district of the Limpopo Province. A questionnaire containing demographic data, information on general and ocular effects of HIV/AIDS was used to collect information from the learners, following a pilot study involving 20 high school learners. Data was analyzed with Statistical Packages for Social Sciences (SPSS) computer program version 16. Descriptive statistics (range, mean, standard deviations and frequencies) was used to describe the findings, and analysis of covariance (ANCOVA) model was used to model the scores on each of the dependent variables i.e. general knowledge of HIV/AIDS and basic knowledge of the effects of HIV/AIDS on the eye. Results The participants were 2659 black South African learners in grades 10 to 12 in the high schools. Eighty eight percent were from rural high schools and (12%) were from a semi-urban high school. Their ages ranged from 14 to 28 years with a mean age of 17.82 and SD of ±1.766 years. The participants included (46.4%) males,(53.1%) females, and (0.5%) learners did not indicate their gender.The meaning of the acronym HIV was known by 63.6% of the participants, and these included 65.8% of the females and 61.5% of males. A lesser proportion (61.5%) knew what the acronym AIDS stands for. They included 70.9% of the females and 60.8% of the males. Knowledge about the different modes of HIV transmission varied from 87.0% (transmission through unprotected sex) to 62.5% (transmission from mother-to–child during pregnancy). Regarding the misconception on the modes of HIV/AIDS transmission, a majority (81.5%) of the learners knew that HIV/AIDS could not be transmitted from one person to another through hugging a person infected with HIV; this percentage includes 82.6% of the females and 80.3% of the males.Only two respondents (0.1%) out of the total population knew the meaning of window period in HIV and they were both females. Only about a third (33.2%) knew the difference between HIV positive and negative results. Majority (85.9%) knew that it is important for one to know his or her HIV status. However, only 5.6% knew the reason why people should know their HIV status. Many (60.1%) knew that the manifestation of HIV symptoms can take many years to develop on an HIV infected person, and 54.9% knew that immune system suppression is the first effect of HIV on the body. Knowledge of the effects of HIV on the body during the seroconversion phase (acute phase), varies from 29.9% (HIV can cause continuous nausea) to 73.0% (HIV can cause tiredness). On the facilities that can be used to test for HIV status, knowledge of the participants varied from 93.4% (knew that HIV test can be done at a hospital) to 34.2% (HIV test can be done at the offices of family general medical practitioner). Only a few (27.8%) knew that HIV/ AIDS can affect the eye. Many (65.5%) of the participants knew that an ophthalmologist or an optometrist should be consulted for ocular problems that are related to HIV/AIDS. Knowledge on the effects of HIV on the eye ranges from 20.6% (HIV can cause an itching and burning sensation in the eye) to 58.6% (HIV can cause severe headaches). Forty six percent knew that HIV can cause blindness. Less than half of the participants (46.9%) knew that exchanging contact lenses with the infected person could not transmit HIV from an HIV positive person. Generally the performance was poor on the ocular manifestation of HIV/AIDS. Young learners were more knowledgeable than the older ones, for both general knowledge of HIV/AIDS and knowledge of the effect of HIV/AIDS on the eye (p < 0.05). Gender of the participants was not statistically significant for both components of the survey (p > 0.05). The pattern of performance among the grades across the schools was not consistent for both components of the survey. Also ages of the learners and their grades did not correspond in terms of performance in this study. Conclusion and recommendations General knowledge of HIV/AIDS was fairly good, but the basic knowledge of the effects of HIV/AIDS on the eye was poor. Therefore, to improve the knowledge about HIV/AIDS of the target population people, there is a need for more awareness campaigns in the rural areas of South Africa. Also, it is recommended that basic knowledge of the effects of HIV/AIDS on the eye should be included in the awareness campaigns (e.g. TV, newspapers, radio, magazines, fliers and HIV/AIDS workshops) and should also be integrated into HIV education syllabus as early as primary level. Educators teaching life orientation and life skills should have regular continuing educational programmes to increase their knowledge on the subject of HIV/AIDS and its effects on organs of the body such as the eye. / University of Limpopo

Syfte: Syftet var att ta reda på vilken metod som är lämpligast att använda för synfältsundersökning vid ett körkortstest hos optiker samt vilken metod det är vanligast att optiker i Sverige använder idag. Dessutom var syftet att utreda varför optiker inte får använda konfrontationstest då det är den metod läkare ska använda för synfältsundersökning enligt körkortsföreskrifterna. Metod: En enkätundersökning med 275 deltagande optiker gjordes. De fick besvara ett fåtal frågor kring vilken metod de använder när de undersöker synfältet vid ett körkortstest samt deras kunskap och inställning till bestämmelserna kring vilken metod som skall användas utav optiker och läkare. Enkätundersökningen publicerades med web-enkätprogrammet Easy Survey. Resultat: Enkätundersökningen visade att endast 58,5 % av optiker i Sverige använder sig av den speciellt avsedda apparaturen. 34,9 % av deltagarna svarade att de använde sig av Donders konfrontationstest. Undersökningen visade på att många optiker i Sverige inte vet vilken metod de enligt föreskriften från 2008 ska använda. Dessutom visar resultaten att en klar majoritet av dem inte förstår varför inte optiker får använda samma metod som läkare för synfältsundersökning vid ett körkortstest. Slutsats: Studien visar att en majoritet av optiker i Sverige använder den av myndigheten rekommenderade metoden men att många också använder Donders. Ett konfrontationstest borde vara mer lämpligt att använda för att undersöka synfältet vid en synprövning för körkort hos optiker än en synfältsapparat. Optiker har tillräckligt stor kunskap för att klara av att använda Donders konfrontationstest och när det utförs korrekt verkar det vara mer tillförlitligt än en apparatur så som Campitestet, då det undersöker synfältet mer utförligt.

<strong>Purpose:</strong> Although orthokeratology (non-surgical corneal reshaping, Corneal Refractive Therapy, CRT®) has been used for almost a half century, contemporary CRT's outcomes and mechanisms still require investigation. A series of studies was designed to examine different aspects of non-surgical corneal reshaping for myopic and hyperopic corrections, including the efficacy and stability of this procedure, the effect of the lens material characteristics (Dk/t), and the corneal or superficial structural change (e. g. corneal/epithelial thickness) in corneal reshaping. <br /> <strong>Methods:</strong> In the CRT® for myopia (CRT1) study, 20 myopes wore CRT® lenses on one eye and control lenses on the contralateral eye (eye randomized) for one night while sleeping. Corneal topography and refractive error were measured the night prior to lens insertion, immediately after lens removal on the following morning and at 20 and 60 minutes and 3, 6 and 12 hours later. In the CRT® for hyperopia (CRTH) study, 20 ametropes wore CRT®H lenses on one eye for one night while sleeping, the contralateral eye (no lens wear) served as control (eye randomized). Corneal topography, aberrations and refractive error were measured the night prior to lens insertion, immediately after lens removal on the following morning and at 1 and 3, 6, 12 and 28 hours later. In the relatively long term (4 weeks) CRT® for myopia (CRT2) study, 23 myopes wore CRT® lenses overnight and removed their lenses on awakening. Visual Acuity (VA), subjective vision, refractive error, aberrations, and corneal topography were measured at baseline, immediately after lens removal on the first day and 14 hours later, and these measurements were repeated on days 4, 10, and 28. The treatment zone size was demarcated by the change in corneal curvature from negative to positive and vice versa, using tangential difference maps from the corneal topographer. In the study of effects of Dk/t on CRT® for myopia (CRTHDK), 20 myopic subjects were fit with Menicon Z (MZ) lenses (Dk/t=90. 6, Paragon CRT®) on one eye and an Equalens II (EII) CRT® lenses (Dk/t=47. 2) on the contralateral eye (eye randomized). Corneal topography, refractive error and aberrations were measured before lens insertion (baseline), and the following day after overnight lens wear, on lens removal and 1, 3, 6, 12 hours later. In the study of short term effects of CRT® for myopia and hyperopia (STOK), 20 ametropes wore CRT® and CRT®H lenses in a random order on one eye (randomly selected). The lenses were worn for 15, 30 and 60 minutes (randomly ordered, with each period taking place on a different day). Refractive error, aberrations, corneal topography, and corneal/epithelial thickness (using OCT) were measured before and after lens wear. The measurements were performed on the control eyes at 60 minutes only. <br /> <strong>Results:</strong> In the CRT1 study, after one night of CRT® for myopia, the central cornea flattened and the mid-periphery steepened, and myopia reduced. In the CRTH study, after one night of CRT® for hyperopia, the central cornea steepened and the para-central region flattened, myopia was induced or hyperopia was reduced, all aberrations except for the astigmatism increased and signed spherical aberration (SA) shifted from positive to negative. In the CRT2 study, after 4 weeks of CRT® lens wear, in general, the treatment zones stabilized by day 10, vision improved, myopia diminished, total aberration and defocus decreased and higher order aberrations (HOAs) including coma and SA increased. The visual, optical and subjective parameters became stable by day 10. In the CRTHDK study, after one night of CRT® (MZ vs. EII) lens wear, the central corneal curvature and aberration were similar with a slight exception: The mid-peripheral corneal steepening was greater in the EII (lower Dk/t) lens-wearing eyes compared to the MZ (higher Dk/t) eyes. In the STOK study, after brief CRT® and CRT®H lens wear, significant changes occurred from the 15 minutes time point: The corneal shape and optical performance changed in a predictable way; the central cornea swelled less than the mid-periphery after CRT® lens wear, whereas the central cornea swelled more than the para-central region after CRT®H lens wear; the central epithelium was thinner than the mid-periphery after CRT® lens wear and was thicker than the para-central region after CRT®H lens wear. <br /> <strong>Conclusion:</strong> After one night of lens wear, CRT® and CRTH® lenses were effective for myopia and hyperopia correction, respectively. In the 4 week CRT study, the treatment zone size changed during the first 10 days. Its size was associated with VA, refractive error, aberrations, and subjective vision. In the CRTHDK study, after one night of lens wear, changes in corneal shape were slightly different, with more mid-peripheral steepening in the lower Dk lens-wearing eyes compared to the higher Dk lens-wearing eyes. Changes in central corneal shape and optical performance were similar in both eyes. In the STOK study, CRT® lenses for myopia and hyperopia induced significant structural and optical changes in as little as 15 minutes. The cornea, particularly the epithelium, is remarkably moldable, with very rapid steepening and flattening possible in a small amount of time.

The wettability of contact lenses has become an area of intense research, with the belief that the more "hydrophilic" or wettable the lens surface is, the more comfortable the lens may be, as the posterior surface of the eyelid will move more smoothly over it, hence increasing comfort. <br /><br /> There are many ways to assess the wettability of a given material, namely sessile drop,¹ captive bubble ² or Wilhelmy plate. ³ This thesis used the sessile drop method to determine the surface wettability of various hydrogel contact lens materials, by measuring the advancing contact angle made between the lens surface and a pre-determined volume of HPLC-grade water. This was followed by measuring the surface wettability following periods in which the lens materials were soaked in various contact lens care regimens. Further studies determined wettability of lens materials after various periods of in-eye wear and finally a study was undertaken to evaluate if a novel biological technique could be used to differentiate proteins that deposit on hydrogel lens materials that may affect wettability and cause discomfort. <br /><br /> A variety of hydrogel lenses, taken directly from their packaging and after soaking in various care regimens, were analyzed to determine their sessile drop advancing contact angles, in vitro. These studies indicated that poly-2-hydroxyethylmethacrylate (pHEMA)-based lenses are inherently more wettable than silicone-based lenses, unless they have a surface treatment that completely covers the hydrophobic siloxane groups. Additionally, certain combinations of lens materials and care regimens produce inherently more wettable surfaces when measured in vitro. <br /><br /> Suitable methods to assess contact lens wettability ex vivo, or after subjects had worn lenses for set periods of time, were developed. It was determined that using latex gloves to remove lenses had no impact upon the lens surface wettability and that rinsing of the lens surface after removal from the eye was required to determine the wettability of the underlying polymer. <br /><br /> The final wettability studies involved an analysis of various lens materials from clinical studies conducted within the Centre for Contact Lens Research (CCLR). These studies investigated differences in wettability between silicone hydrogel lenses manufactured from differing polymers and variations in ex vivo wettability of several combinations of lens materials and solutions, worn for varying periods of time. <br /><br /> A novel method to investigate proteins extracted from lenses using 2D-Difference in Gel Electrophoresis (DIGE) found that this technique could be used to analyze proteins extracted from contact lenses. The data obtained showed that there was no difference between a group of subjects who were symptomatic of lens-induced dryness or a control group, and that care solutions had a minimal influence on the pattern of deposition seen. <br /><br /> The overall conclusion of these studies is that hydrogel lens wettability is affected by the polymer composition and that care regimen components can modify the surface wettability.

Many individuals with impaired vision experience a decreased quality of life. Quality of life is defined as "the degree to which an individual enjoys the important possibilities of their life. " Vision rehabilitation outcomes primarily focus on the functional impacts of interventions, with less attention being paid to any associated psychosocial impacts. This study examines the relationship between measures of visual function status and psychosocial status in individuals acquiring low vision assistive devices for the first time. One hundred and twenty subjects were evaluated after purchasing their first low vision device from a University-based low vision clinic. The measures used were the National Eye Institute Visual Function Questionnaire (NEI-VFQ 25) and the Psychosocial Impact of Assistive Devices Scales (PIADS). The NEI-VFQ 25 measures the status of visual function, while PIADS is a device impact measure, which explores the psychosocial impact of devices on three domains: competence, adaptability, and self-esteem. This study determines the strength of association between these two measures at initial and follow-up administrations, and between each subsequent measure as a result of the time interval between administrations, in addition to assessing whether or not a change in stability for the measures occurred over time. Modest strengths of associations were anticipated and the short time interval was not expected to be a factor in change in stability of the measures. The expectation was that subjective reports of functional changes should have a moderate correlation with psychosocial impact.

Syfte: Syftet var att undersöka prevalensen av katarakt i Bolivia under en resa med den svenska hjälporganisationen Vision For All. Metod: Undersökningarna utfördes med hjälp av handhållet oftalmoskop av modellen Heine Beta 200S. Undersökningen genomfördes i genomfallande ljus på ca 30 cm avstånd mellan patient och undersökare. De eventuella opaciteterna i linsen graderades efter hur omfattande de var där grad 0 var inga opaciteter och grad 4 var helt opak lins och grad 5 visade att linsen inte kunde undersökas på grund av oklar hornhinna eller dylikt. Patienterna sökte själva upp undersökningsplatserna som var belägna i städerna Santa Cruz de la Sierra och San José de Chiquitos. Eftersom det fanns begränsat med plats i bagageutrymmet på resan till Bolivia, valdes en väldigt enkel metod som inte krävde avancerad utrustning. Resultat: Totalt medverkade 453 personer i studien, det vill säga 906 ögon. Medelåldern var 50,19 ±15,51 år. 62, 91% av personerna som undersöktes var kvinnor. Det totala antalet ögon som hade någon grad av katarakt var 241 stycken, vilket motsvarar 26,60%. Vid jämförelse av de olika städerna, Santa Cruz de la Sierra och San José de Chiquitos, visade det att framförallt prevalensen av katarakt grad 3 var högre i San José de Chiquitos. Slutsats: I båda städerna, Santa Cruz de la Sierra och San José de Chiquitos finns stora problem med katarakt. Förutom att försöka öka tillgängligheten på operationer, borde det läggas resurser på att tillgängliggöra information gällande vikten av att skydda sina ögon vid stark UV- strålning.

<b>Purpose:</b> Assess the relationship between tear film drying and sensation between blinks. <b>Methods:</b> MATLAB sampled a slitlamp video camera, a potentiometer and a microphone while subjects kept one eye open for as long as possible. 23 subjects rated the intensity of the ocular sensation while video and voice data were collected simultaneously. The tear drying on the cornea was measured. <b>Results:</b> The sensation was triphasic. Two linear functions described the latter 2 parts of the data (r &#8805; 0. 95). The correlation between TBUT and the elbow in the time-discomfort function was 0. 72. Extent of tear film drying was linearly correlated to time (median correlation = 0. 88). The correlation between the discomfort elbow and image elbow was 0. 93 with single data pair for each subject. Analysis of sensation characteristics showed significant differences between itching and burning for both intensity and time (p = 0. 03 and p = 0. 02 respectively). <b>Conclusions:</b> Simultaneous recording of ocular surface appearance, discomfort intensity and attributes of sensation provide novel information about the development of discomfort during ocular surface drying. The rapid increase in discomfort proceeding blinking has been quantified and the relationship between the time course of drying and discomfort is elucidated.

Purpose: The aim of the study was to delineate differences in saccade characteristics between a population of athletes and non athletes. Aspects specifically investigated were latency, accuracy, peak velocity, and gain adaptation of saccades using both increasing and decreasing paradigms. Methods: A sample of 28 athletes (varsity badminton and squash players) and 18 non athletes (< 3 hour/week in sports) were studied. Eye movements were recorded at 120Hz using a video based eye tracker (ELMAR 2020). Each subject participated in 2 sessions on separate days. Baseline saccade responses to dot stimuli were measured in both sessions (stimulus size: 5-25 deg). The first session involved a gain decreasing paradigm, induced by displacing the stimulus backwards by 3 degrees from the initial target step (12 deg) for 500 trials. In the 2nd session a gain increase was induced by displacing the stimuli by 3 degrees in the forward direction. The latency and accuracy were calculated from the baseline. The asymptotic peak velocity was calculated from the main sequence (amplitude vs. peak velocity). The amplitude gains, calculated from the adaptation phase, were averaged for every 100 saccade responses. The averaged gains were normalized with respect to the baseline, fitted with a 3rd order polynomial, and differentiated to obtain the rate of change. Differences between the groups were compared using a regression analysis. Results: There were no significant differences in latency, accuracy, and asymptotic peak velocity between athletes and non athletes. No significant differences were seen between the two groups in the magnitude of saccadic adaptation, both for decreasing (- 15% in both groups) and increasing (athletes + 7% and non athletes + 5%) paradigms. However, athletes showed a significantly faster rate of adaptation for the gain increasing paradigm (F = 17. 96[3,6]; p = 0. 002). A significant difference was not observed in the rate of adaptation for the gain decreasing adaptation (F = 0. 856[3,6]; p = 0. 512). Conclusions: The study showed that the athletes do not respond better in terms of reaction time or accuracy of saccades. The significant difference in the rate of change of adaptation between the groups shows that online modification of saccades in the positive direction, although not greater in magnitude, occurs quicker in athletes than non athletes.

<strong>Purpose:</strong> Although orthokeratology (non-surgical corneal reshaping, Corneal Refractive Therapy, CRT®) has been used for almost a half century, contemporary CRT's outcomes and mechanisms still require investigation. A series of studies was designed to examine different aspects of non-surgical corneal reshaping for myopic and hyperopic corrections, including the efficacy and stability of this procedure, the effect of the lens material characteristics (Dk/t), and the corneal or superficial structural change (e. g. corneal/epithelial thickness) in corneal reshaping. <br /> <strong>Methods:</strong> In the CRT® for myopia (CRT1) study, 20 myopes wore CRT® lenses on one eye and control lenses on the contralateral eye (eye randomized) for one night while sleeping. Corneal topography and refractive error were measured the night prior to lens insertion, immediately after lens removal on the following morning and at 20 and 60 minutes and 3, 6 and 12 hours later. In the CRT® for hyperopia (CRTH) study, 20 ametropes wore CRT®H lenses on one eye for one night while sleeping, the contralateral eye (no lens wear) served as control (eye randomized). Corneal topography, aberrations and refractive error were measured the night prior to lens insertion, immediately after lens removal on the following morning and at 1 and 3, 6, 12 and 28 hours later. In the relatively long term (4 weeks) CRT® for myopia (CRT2) study, 23 myopes wore CRT® lenses overnight and removed their lenses on awakening. Visual Acuity (VA), subjective vision, refractive error, aberrations, and corneal topography were measured at baseline, immediately after lens removal on the first day and 14 hours later, and these measurements were repeated on days 4, 10, and 28. The treatment zone size was demarcated by the change in corneal curvature from negative to positive and vice versa, using tangential difference maps from the corneal topographer. In the study of effects of Dk/t on CRT® for myopia (CRTHDK), 20 myopic subjects were fit with Menicon Z (MZ) lenses (Dk/t=90. 6, Paragon CRT®) on one eye and an Equalens II (EII) CRT® lenses (Dk/t=47. 2) on the contralateral eye (eye randomized). Corneal topography, refractive error and aberrations were measured before lens insertion (baseline), and the following day after overnight lens wear, on lens removal and 1, 3, 6, 12 hours later. In the study of short term effects of CRT® for myopia and hyperopia (STOK), 20 ametropes wore CRT® and CRT®H lenses in a random order on one eye (randomly selected). The lenses were worn for 15, 30 and 60 minutes (randomly ordered, with each period taking place on a different day). Refractive error, aberrations, corneal topography, and corneal/epithelial thickness (using OCT) were measured before and after lens wear. The measurements were performed on the control eyes at 60 minutes only. <br /> <strong>Results:</strong> In the CRT1 study, after one night of CRT® for myopia, the central cornea flattened and the mid-periphery steepened, and myopia reduced. In the CRTH study, after one night of CRT® for hyperopia, the central cornea steepened and the para-central region flattened, myopia was induced or hyperopia was reduced, all aberrations except for the astigmatism increased and signed spherical aberration (SA) shifted from positive to negative. In the CRT2 study, after 4 weeks of CRT® lens wear, in general, the treatment zones stabilized by day 10, vision improved, myopia diminished, total aberration and defocus decreased and higher order aberrations (HOAs) including coma and SA increased. The visual, optical and subjective parameters became stable by day 10. In the CRTHDK study, after one night of CRT® (MZ vs. EII) lens wear, the central corneal curvature and aberration were similar with a slight exception: The mid-peripheral corneal steepening was greater in the EII (lower Dk/t) lens-wearing eyes compared to the MZ (higher Dk/t) eyes. In the STOK study, after brief CRT® and CRT®H lens wear, significant changes occurred from the 15 minutes time point: The corneal shape and optical performance changed in a predictable way; the central cornea swelled less than the mid-periphery after CRT® lens wear, whereas the central cornea swelled more than the para-central region after CRT®H lens wear; the central epithelium was thinner than the mid-periphery after CRT® lens wear and was thicker than the para-central region after CRT®H lens wear. <br /> <strong>Conclusion:</strong> After one night of lens wear, CRT® and CRTH® lenses were effective for myopia and hyperopia correction, respectively. In the 4 week CRT study, the treatment zone size changed during the first 10 days. Its size was associated with VA, refractive error, aberrations, and subjective vision. In the CRTHDK study, after one night of lens wear, changes in corneal shape were slightly different, with more mid-peripheral steepening in the lower Dk lens-wearing eyes compared to the higher Dk lens-wearing eyes. Changes in central corneal shape and optical performance were similar in both eyes. In the STOK study, CRT® lenses for myopia and hyperopia induced significant structural and optical changes in as little as 15 minutes. The cornea, particularly the epithelium, is remarkably moldable, with very rapid steepening and flattening possible in a small amount of time.

The wettability of contact lenses has become an area of intense research, with the belief that the more "hydrophilic" or wettable the lens surface is, the more comfortable the lens may be, as the posterior surface of the eyelid will move more smoothly over it, hence increasing comfort. <br /><br /> There are many ways to assess the wettability of a given material, namely sessile drop,¹ captive bubble ² or Wilhelmy plate. ³ This thesis used the sessile drop method to determine the surface wettability of various hydrogel contact lens materials, by measuring the advancing contact angle made between the lens surface and a pre-determined volume of HPLC-grade water. This was followed by measuring the surface wettability following periods in which the lens materials were soaked in various contact lens care regimens. Further studies determined wettability of lens materials after various periods of in-eye wear and finally a study was undertaken to evaluate if a novel biological technique could be used to differentiate proteins that deposit on hydrogel lens materials that may affect wettability and cause discomfort. <br /><br /> A variety of hydrogel lenses, taken directly from their packaging and after soaking in various care regimens, were analyzed to determine their sessile drop advancing contact angles, in vitro. These studies indicated that poly-2-hydroxyethylmethacrylate (pHEMA)-based lenses are inherently more wettable than silicone-based lenses, unless they have a surface treatment that completely covers the hydrophobic siloxane groups. Additionally, certain combinations of lens materials and care regimens produce inherently more wettable surfaces when measured in vitro. <br /><br /> Suitable methods to assess contact lens wettability ex vivo, or after subjects had worn lenses for set periods of time, were developed. It was determined that using latex gloves to remove lenses had no impact upon the lens surface wettability and that rinsing of the lens surface after removal from the eye was required to determine the wettability of the underlying polymer. <br /><br /> The final wettability studies involved an analysis of various lens materials from clinical studies conducted within the Centre for Contact Lens Research (CCLR). These studies investigated differences in wettability between silicone hydrogel lenses manufactured from differing polymers and variations in ex vivo wettability of several combinations of lens materials and solutions, worn for varying periods of time. <br /><br /> A novel method to investigate proteins extracted from lenses using 2D-Difference in Gel Electrophoresis (DIGE) found that this technique could be used to analyze proteins extracted from contact lenses. The data obtained showed that there was no difference between a group of subjects who were symptomatic of lens-induced dryness or a control group, and that care solutions had a minimal influence on the pattern of deposition seen. <br /><br /> The overall conclusion of these studies is that hydrogel lens wettability is affected by the polymer composition and that care regimen components can modify the surface wettability.