The primary objective of this study was to quantify and characterise lipid deposition on soft (hydrogel) contact lenses, particularly those containing siloxane components. Studies involving a variety of <em>in vitro</em> doping and <em>in vivo</em> worn contact lenses were undertaken, in which lipid deposition was analyzed by either TLC or HPLC. Specific experiments were completed to optimize a method to extract the lipid from the lens materials, to compare the total lipid deposition on nine different hydrogel lenses and to analyze the effect that lipid deposition had on wettability. A method for extracting lipid from contact lenses using 2:1 chloroform: methanol was developed. This study also showed that siloxane-containing contact lens materials differ in the degree to which they deposit lipid, which is dependent upon their chemical composition. Small differences in lipid deposition that occur due to using variations in cleaning regimens were not identifiable through TLC, and required more sophisticated analysis using HPLC. Contact lens material wettability was found to be influenced by <em>in vitro</em> lipid deposition. Specifically, conventional hydrogels and plasma surface-treated silicone-hydrogel materials experienced enhanced wettability with lipid deposition. Reverse-phase HPLC techniques were able to quantify lipid deposits with increased sensitivity and accuracy. From the HPLC studies it was found that contact lens material, concentration of the lipid doping solution, and the composition of the lipid doping solution in <em>in vitro</em> deposition studies influenced the ultimate amount and composition of lipid deposits. <em>In vivo</em> HPLC studies showed that the final lipid deposition pattern was influenced by the interaction between the composition of the tear film and the various silicone hydrogel contact lens materials. In conclusion, HPLC analysis methods were more sensitive and quantitative than TLC. Lipid deposition was ultimately influenced by the concentration and composition of the lipid in the tear film and the contact lens material. Contact lens wettability was influenced by the presence and deposition of lipid onto the contact lens surfaces. Finally, this reverse-phase HPLC lipid analysis protocol was not the most sensitive, robust, or accurate. In the future, other methods of analysis should be explored.

Purposes: To use optical coherence tomography (OCT) to image and quantify the effect of various corneal conditions, in terms of corneal, stromal and epithelial thickness, and light backscatter. To assess the changes caused by overnight orthokeratology (Corneal Refractive Therapy; CRT^TM) lens wear, keratoconus and laser in-situ keratomileusis (LASIK) refractive surgery, each of which may lead to topographical alterations in corneal thickness either by temporary moulding, degeneration, or permanent laser ablation, respectively. <br /><br /> Methods: Topographical thickness of the cornea was measured using OCT in all studies. The CRT^TM studies investigated myopic and hyperopic treatment, throughout the day. The myopic studies followed lens wear over a 4 week period, which was extended to 12 months, and investigated the thickness changes produced by two lenses of different oxygen transmissibility. CRT^TM for hyperopia (CRTH^TM) was evaluated after a single night of lens wear. <br /><br /> In the investigation of keratoconus, OCT corneal thickness values were compared to those obtained from Orbscan II (ORB) and ultrasound pachymetry (UP). A new fixation device was constructed to aid in the measurement of topographical corneal and epithelial thickness along 8 directions of gaze. Pachymetry maps were produced for the normal non-lens wearing cornea, and compared with the rigid gas permeable (RGP) lens wearing cornea and the keratoconic cornea. <br /><br /> Thickness changes prior to, and following LASIK were measured and monitored throughout six months. Myopic and hyperopic correction was investigated individually, as the laser ablation profiles differ for each type of procedure. The LASIK flap interface was also evaluated by using light backscatter data to monitor healing. <br /><br /> Results: Following immediate lens removal after myopic CRT^TM, the central cornea swelled less than the periphery, with corneal swelling recovering to baseline levels within 3 hours. The central epithelium decreased and mid-peripheral epithelium increased in thickness, with a more gradual recovery throughout the day. There also seemed to be an adaptation effect on the cornea and epithelium, showing a reduced amount of change by the end of the 4 week study period. The thickness changes did not alter dramatically during the 12 month extended study. In comparing the two lens materials used for myopic CRT^TM (Dk/t 91 vs. 47), there were differences in stromal swelling, but no differences in the central epithelial thinning caused by lens wear. There was a statistically insignificant asymmetry in mid-peripheral epithelial thickening between eyes, with the lens of lower Dk causing the greater amount of thickening. Hyperopic CRT^TM produced a greater increase in central stromal and central epithelial thickness than the mid-periphery. Once again, the stroma recovered faster than the epithelium, which remained significantly thicker centrally for at least six hours following lens removal. <br /><br /> Global pachymetry measurements of the normal cornea and epithelium found the periphery to be thicker than the centre. The superior cornea and epithelium was thicker than the inferior. In the measurement of the keratoconic cornea, OCT and ORB correlated well in corneal thickness values. UP measured greater values of corneal thickness. The keratoconic epithelium was thinner than normal, and more so over the apex of the cone than at the centre. The location of the cone was most commonly found in the inferior temporal region. Central epithelial thickness was thinner in keratoconics than in RGP lens wearers, which in turn was thinner than in non-lens wearers. <br /><br /> Following LASIK surgery for both myopia and hyperopia, the topographical OCT thickness profiles showed stromal thinning in the areas of ablation. The central myopic cornea showed slight regression at 6 months. During early recovery, epithelial thickness increased centrally in hyperopes and mid-peripherally in myopes. By the end of the 6 month study, mid-peripheral epithelial thickness was greater than the centre in both groups of subjects. The light backscatter profiles after LASIK showed a greater increase in backscatter on the anterior side of the flap interface (nearer the epithelium), than the posterior side (in the mid-stroma) during healing. The flap interface was difficult to locate in the OCT images at 6 months. <br /><br /> Conclusion: All the CRT^TM lenses used in this project produced more corneal swelling than that seen normally overnight without lens wear. In order for these lenses to be worn safely for long periods of time without affecting the health of the cornea, they need to be manufactured from the highest oxygen transmissible material available. The long-term effect of thinning on the epithelium's barrier properties needs to be monitored closely. <br /><br /> Global topographical thickness of the cornea and epithelium was measured using OCT in normal, RGP lens wearing and keratoconic eyes. Corneal and epithelial thickness was not symmetrical across meridians. The epithelium of RGP lens wearers was slightly thinner than normal, but not as thin as in keratoconics, suggesting that the epithelial change seen in keratoconus is mainly due to the condition. <br /><br /> Post-LASIK corneal and epithelial thickness profiles were not the same for myopic and hyperopic subjects, since the ablation patterns vary. Epithelial thickening in the mid-periphery had not recovered by six months in myopes or hyperopes, possibly indicating epithelial hyperplasia. Light backscatter profiles were used to monitor the recovery of the LASIK flap interface, showing the band of light backscatter around the flap interface to decrease as the cornea healed.

Over 60 proteins have been detected in the tear film and among these lysozyme has attracted the greatest attention. Several techniques for elucidating the identity, quantity and conformation of lysozyme deposited on soft contact lenses have been developed. Lysozyme also deposits on the newly introduced silicone hydrogel (SH) lens materials, but in extremely low levels compared to conventional hydrogel lenses. Hence, a major analytical complication with the study of the SH contact lens materials relates to the minute quantity of deposited lysozyme. The first project of this thesis involved the development of a method whereby lysozyme mass extracted from SH lens materials would be preserved over time and would be compatible with an optimized Western blotting procedure. This methodological development was incorporated into a clinical study (CLENS-100® and Silicone Hydrogels ? CLASH study) wherein the difference in the degree of total protein, the difference in lysozyme deposition and activity recovered from lotrafilcon A SH lens material when subjects used surfactant containing rewetting drops (CLENS-100®) versus control saline was investigated. The remaining experiments were in vitro experiments wherein the lenses were doped in artificial lysozyme solution containing ¹²⁵I-labeled lysozyme. These experiments were performed to gain insight into the kinetics of lysozyme deposition on SH lens materials and also the efficacy of a reagent in extracting lysozyme from SH lens materials. A protocol was developed whereby the percentage loss of lysozyme mass found on lotrafilcon A SH lenses was reduced from approximately 33% to <1% (p<0. 001), following extraction and resuspension. The results from the CLASH study demonstrated that when subjects used a surfactant containing rewetting drop instead of a control saline drop total protein deposition (1. 2±0. 7 µg/lens versus 1. 9±0. 8 µg/lens, p<0. 001), lysozyme deposition (0. 7±0. 5 µg/lens versus 1. 1±0. 7 µg/lens, p<0. 001) and percentage lysozyme denaturation (76±10% versus 85±7%, p=0. 002) were all reduced. The results from the kinetics study demonstrated that lysozyme accumulated rapidly on etafilcon A lenses (1 hr, 98±8 µg/lens), reached a maximum on the 7th day (1386±21 µg/lens) and then reached a plateau (p=NS). Lysozyme accumulation on FDA Group II and SH lenses continued to increase across all time periods, with no plateau being observed (p<0. 001). The results from the extraction efficiency study showed that 0. 2% trifluoroacetic acid/ acetonitrile was 98. 3±1. 1% and 91. 4±1. 4% efficient in extracting lysozyme deposited on etafilcon A and galyfilcon lenses, while the lysozyme extraction efficiency was 66. 3±5. 3 % and 56. 7±3. 8% for lotrafilcon A and balafilcon lens materials (p<0. 001). The results from these studies re-emphasize that novel SH lens materials are highly resistant to protein deposition and demonstrate high levels of biocompatibility.

The primary objective of this study was to quantify and characterise lipid deposition on soft (hydrogel) contact lenses, particularly those containing siloxane components. Studies involving a variety of <em>in vitro</em> doping and <em>in vivo</em> worn contact lenses were undertaken, in which lipid deposition was analyzed by either TLC or HPLC. Specific experiments were completed to optimize a method to extract the lipid from the lens materials, to compare the total lipid deposition on nine different hydrogel lenses and to analyze the effect that lipid deposition had on wettability. A method for extracting lipid from contact lenses using 2:1 chloroform: methanol was developed. This study also showed that siloxane-containing contact lens materials differ in the degree to which they deposit lipid, which is dependent upon their chemical composition. Small differences in lipid deposition that occur due to using variations in cleaning regimens were not identifiable through TLC, and required more sophisticated analysis using HPLC. Contact lens material wettability was found to be influenced by <em>in vitro</em> lipid deposition. Specifically, conventional hydrogels and plasma surface-treated silicone-hydrogel materials experienced enhanced wettability with lipid deposition. Reverse-phase HPLC techniques were able to quantify lipid deposits with increased sensitivity and accuracy. From the HPLC studies it was found that contact lens material, concentration of the lipid doping solution, and the composition of the lipid doping solution in <em>in vitro</em> deposition studies influenced the ultimate amount and composition of lipid deposits. <em>In vivo</em> HPLC studies showed that the final lipid deposition pattern was influenced by the interaction between the composition of the tear film and the various silicone hydrogel contact lens materials. In conclusion, HPLC analysis methods were more sensitive and quantitative than TLC. Lipid deposition was ultimately influenced by the concentration and composition of the lipid in the tear film and the contact lens material. Contact lens wettability was influenced by the presence and deposition of lipid onto the contact lens surfaces. Finally, this reverse-phase HPLC lipid analysis protocol was not the most sensitive, robust, or accurate. In the future, other methods of analysis should be explored.

Purposes: To use optical coherence tomography (OCT) to image and quantify the effect of various corneal conditions, in terms of corneal, stromal and epithelial thickness, and light backscatter. To assess the changes caused by overnight orthokeratology (Corneal Refractive Therapy; CRT^TM) lens wear, keratoconus and laser in-situ keratomileusis (LASIK) refractive surgery, each of which may lead to topographical alterations in corneal thickness either by temporary moulding, degeneration, or permanent laser ablation, respectively. <br /><br /> Methods: Topographical thickness of the cornea was measured using OCT in all studies. The CRT^TM studies investigated myopic and hyperopic treatment, throughout the day. The myopic studies followed lens wear over a 4 week period, which was extended to 12 months, and investigated the thickness changes produced by two lenses of different oxygen transmissibility. CRT^TM for hyperopia (CRTH^TM) was evaluated after a single night of lens wear. <br /><br /> In the investigation of keratoconus, OCT corneal thickness values were compared to those obtained from Orbscan II (ORB) and ultrasound pachymetry (UP). A new fixation device was constructed to aid in the measurement of topographical corneal and epithelial thickness along 8 directions of gaze. Pachymetry maps were produced for the normal non-lens wearing cornea, and compared with the rigid gas permeable (RGP) lens wearing cornea and the keratoconic cornea. <br /><br /> Thickness changes prior to, and following LASIK were measured and monitored throughout six months. Myopic and hyperopic correction was investigated individually, as the laser ablation profiles differ for each type of procedure. The LASIK flap interface was also evaluated by using light backscatter data to monitor healing. <br /><br /> Results: Following immediate lens removal after myopic CRT^TM, the central cornea swelled less than the periphery, with corneal swelling recovering to baseline levels within 3 hours. The central epithelium decreased and mid-peripheral epithelium increased in thickness, with a more gradual recovery throughout the day. There also seemed to be an adaptation effect on the cornea and epithelium, showing a reduced amount of change by the end of the 4 week study period. The thickness changes did not alter dramatically during the 12 month extended study. In comparing the two lens materials used for myopic CRT^TM (Dk/t 91 vs. 47), there were differences in stromal swelling, but no differences in the central epithelial thinning caused by lens wear. There was a statistically insignificant asymmetry in mid-peripheral epithelial thickening between eyes, with the lens of lower Dk causing the greater amount of thickening. Hyperopic CRT^TM produced a greater increase in central stromal and central epithelial thickness than the mid-periphery. Once again, the stroma recovered faster than the epithelium, which remained significantly thicker centrally for at least six hours following lens removal. <br /><br /> Global pachymetry measurements of the normal cornea and epithelium found the periphery to be thicker than the centre. The superior cornea and epithelium was thicker than the inferior. In the measurement of the keratoconic cornea, OCT and ORB correlated well in corneal thickness values. UP measured greater values of corneal thickness. The keratoconic epithelium was thinner than normal, and more so over the apex of the cone than at the centre. The location of the cone was most commonly found in the inferior temporal region. Central epithelial thickness was thinner in keratoconics than in RGP lens wearers, which in turn was thinner than in non-lens wearers. <br /><br /> Following LASIK surgery for both myopia and hyperopia, the topographical OCT thickness profiles showed stromal thinning in the areas of ablation. The central myopic cornea showed slight regression at 6 months. During early recovery, epithelial thickness increased centrally in hyperopes and mid-peripherally in myopes. By the end of the 6 month study, mid-peripheral epithelial thickness was greater than the centre in both groups of subjects. The light backscatter profiles after LASIK showed a greater increase in backscatter on the anterior side of the flap interface (nearer the epithelium), than the posterior side (in the mid-stroma) during healing. The flap interface was difficult to locate in the OCT images at 6 months. <br /><br /> Conclusion: All the CRT^TM lenses used in this project produced more corneal swelling than that seen normally overnight without lens wear. In order for these lenses to be worn safely for long periods of time without affecting the health of the cornea, they need to be manufactured from the highest oxygen transmissible material available. The long-term effect of thinning on the epithelium's barrier properties needs to be monitored closely. <br /><br /> Global topographical thickness of the cornea and epithelium was measured using OCT in normal, RGP lens wearing and keratoconic eyes. Corneal and epithelial thickness was not symmetrical across meridians. The epithelium of RGP lens wearers was slightly thinner than normal, but not as thin as in keratoconics, suggesting that the epithelial change seen in keratoconus is mainly due to the condition. <br /><br /> Post-LASIK corneal and epithelial thickness profiles were not the same for myopic and hyperopic subjects, since the ablation patterns vary. Epithelial thickening in the mid-periphery had not recovered by six months in myopes or hyperopes, possibly indicating epithelial hyperplasia. Light backscatter profiles were used to monitor the recovery of the LASIK flap interface, showing the band of light backscatter around the flap interface to decrease as the cornea healed.

Purpose: To investigate whether retinal thickness varies with refractive error. Also secondary to see if there is any difference in retinal thickness between the right and left eye. Methods: The inclusion criteria for the study was subjects without any pathologies, age between 18-45 and refractive error of maximum +0.75 SER and the myopia had no limit, as well as no astigmatism higher then -1.00D. Subjects, which fitted the inclusion criteria for the study, was shown to the OCT room were retinal thickness measurements were acquired first on the right and then left eye. To get the same reading area, the same setup was used and the fixation point was always centered for each patient. After all subjects had undergone the same method the results were analyzed using t-test and regression analysis. Results: The analysis showed a difference between emmetropic eyes and myopic eyes in the peripheral retinal thickness, having the myopes being significantly thinner. The inter myopic analysis showed no difference in retinal thickness in any of the points. This could however be due to the smaller sample size. The comparison between right and left eye showed a good symmetry between the two eyes both in the emmetropic and the myopic group. Conclusions: From this study we can conclude that the myopic group has a thinner peripheral retinal thickness than the emmetropic group. Central retinal thickness is not significantly different but could be due to the smaller sample size. There is no difference in retinal thickness between right and left eye.

SUMMARY Environmental issues are currently a hot topic of debate. Studies within the optics branch have not specifically been conducted previously, so the aim of this study was to determine the extent of environmental-awareness specifically within this branch. A survey, consisting of questions relating to environmental issues, was distributed to 100 randomly-selected opticians in Sweden. Of these 100 surveys, 64 were returned and showed a varied branch-engagement for environmental issues. Results of this survey showed that opticians were best in sorting newspapers, magazines, other paper and hazardous waste. Metal and rigid plastic were not sorted to any larger extent. Choosing environmentally-safe products was not so popular and only six stores always do this. 25 shops turn off electrical machines and equipment over night; while the majority of the remaining stores leave the machines on during the night. 27 stores did not know if their electrical company provided “green electricity”. Results showed that there is a lot of work to be done in making the stores more environmentally friendly. Changes do not have to be great, however all changes can help protect the environment and even result in economic benefits for a practice. • Choose electrical-companies that provide “green electricity” • Sort garbage better • Create an environmental policy in the practice • Discuss environmental issues with suppliers • Request environmentally-safe products from suppliers • Choose environmentally safe products as much as possible • Try to think about the environment when travelling or commuting • Turn off all electrical machines when not in use • Don’t waste water, electricity, chemicals, paper etc. • Get information and get environmentally active / Abstrakt Miljöarbete är i full gång i hela världen och det är ett mycket aktuellt och viktigt ämne. Därför kom funderingar över hur miljöarbetet ser ut i optikbranschen, och om man kunde göra några förbättringar i det. För att ta reda på det skapades en enkät som skickades ut till 100 slumpmässigt utvalda optikerbutiker i Sverige. 64 enkäter besvarades och visade på ett blandat miljöengagemang. Enkätsvaren visade att butikerna var bäst på att källsortera tidningar, annat papper och miljöfarligt avfall, medan de var sämst på att sortera metall och hårdplast. Att alltid välja miljövänliga produkter var inte så vanligt, bara 6 butiker väljer alltid det. Att stänga av de elektriska apparaterna till natten var det 25 butiker som gjorde medan 37 stycken låter apparaterna stå på. 27 stycken butiker visste inte om de anlitade ett elbolag som sålde ”grön el”. 53 butiker tror att de kan påverka miljön till det bättre genom att ”dra sitt strå till stacken”. Enkätsvaren visar dessutom på att det finns en del att jobba med för att göra butikerna miljövänligare. Det behöver inte vara särskilt stora förändringar för att miljöarbetet ska skjuta fart. Vissa miljöinsatser kan faktiskt spara pengar. 2008:O20

Dyslexia is a neurological disorder with genetic origin that affects a person’s word processing ability, their spelling, writing, comprehension and reading, and results in poor academic performance. As a result, optometrists are consulted for assistance with the diagnosis and treatment of a possible vision condition. Optometrists are able to assist with treatment as part of a multidisciplinary management approach, where optometric support is necessary. International studies have indicated that up to 20% of Caucasian school children are affected by dyslexia, while there are no similar figures for African children. Studies have been done to assess the extent of visual defects among Caucasian dyslexics, but not among African dyslexic children. The aim of the study is therefore to determine the prevalence of vision conditions in an African South African population of dyslexic school children, and to investigate the relationship between dyslexia and vision. The possible relationship between dyslexia and vision conditions has been recognized as an important area of study, resulting in research being conducted in many countries. Studies have been undertaken by optometrists and ophthalmologists, who differ in their approach and attitude on how vision conditions affect dyslexia. A review of the literature revealed three broad areas of vision that may impact on reading ability, these being acuity defects, binocular vision and ocular pathology. Acuity defects consist of visual acuity and refractive error. Areas of binocular vision evaluated in the literature include near point convergence, heterophoria, strabismus, accommodative functions, vergence facility and reserves. Hyperopia was the only vision variable that was found to be consistently associated with difficulties with reading, but not causally while findings on other variables were inconclusive. However, all the studies acknowledged the complexity of the condition, and the need for a comprehensive multidisciplinary management approach for its diagnosis and management. The study was undertaken in the city of Durban, South Africa, using a case-control study of two groups of African school children between the ages of 10 and 15. Both study groups consisted of 31 children of normal intelligence, who were matched in gender, race and socio-economic status. The case group attended a school for children with learning disabilities, while the control group attended a mainstream school. At the time of the study, only one school catered for African children with learning disabilities, and only 31 of its pupils were diagnosed with dyslexia. Ethical approval was obtained from the University of KwaZulu-Natal; permission to undertake the study in the identified schools was obtained from the Department of Education, and the school principals consented on behalf of the learners, as it was not always possible to reach the individual parent. The researcher (an optometrist) visited both schools by appointment where rooms were made available to do the testing, and the tests were explained to all participants. The LogMar Acuity Charts were used to assess visual acuity, and static retinoscopy was used to assess refractive error. Binocular vision was tested using the cover test for ocular alignment, the Hirschberg test for strabismus, RAF rule for near point of convergence, ± 2 D flipper lenses for accommodation facilities, Donder’s push up methods, using the RAF rule for amplitude of accommodation, plus and minus lenses for relative accommodation, monocular estimation technique for accommodation posture, and prism bars for vergence reserves. Ocular pathology was assessed using a direct ophthalmoscope. The dyslexic group presented with the following: Refractive errors: hyperopia 6.5%, myopia 6.5%, astigmatism 10%, anisometropia 6.5%, remote near point of convergence 33%, esophoria at near 3%, exophoria at near 9.5%, accommodative infacility 54% and lag of accommodation 39.28%. The dyslexic group had relatively reduced fusional reserve compared to the control group. The control group presented with the following: Refractive errors: hyperopia 3%, astigmatism 13%, anisometropia 6.5%, remote near point of convergence 48%, esophoria at near 0%, exophoria at near 0%, accommodative infacility 33% and lag of accommodation 41.93%. The prevalence of a remote NPC was higher in the control group than in the dyslexic group and there was a statistically significant difference between the two groups: NPC break (p=0.049) and recovery (p=0.046). The prevalence of poor binocular accommodation facility at near was higher in the dyslexic group than in the control group and there was a statistically significant difference between the two groups (p = 0.027). Vision defects such as hyperopia, astigmatism, accommodation lag, convergence insufficiency, poor near point of convergence and accommodative infacility were present in the dyslexic pupils, but they were no more at risk of any particular vision condition than the control group. This study provided the prevalence of vision conditions in a population of African dyslexic children in South Africa, the only vision variable that was significantly more prevalent in the dyslexic population being the binocular accommodation facility at near, although the study was unable to find a relationship between dyslexia and vision. The statistically significant difference may not imply clinical significance due to the small sample size. However, it is recommended that any vision defects detected should be appropriately compensated for as defective vision can make reading more difficult for the dyslexic child. The sample size may have been a limitation; however, this was comparable with studies reviewed, most of which had sample sizes of less than 41. Due to the range of possible ocular conditions that could affect dyslexia, it is recommended that a larger sample size be used to ensure more conclusive results. Testing for relative accommodation with a phoropter would provide more accurate results, and accommodation facility and fusional reserves would be better assessed with suppression control. The study provides information and an indication of research needs regarding the prevalence of vision defects in an African South African population of dyslexic children. / Thesis (M.Optom.)-University of KwaZulu-Natal, Westville, 2010.

Background: Reading rate is a measure of fluency, reflecting the level of reading performance especially in children, which is not typically measured during routine eye examinations. Optometric clinical tests such as Snellen visual acuity are often poor predictors of everyday reading performance, as they test the smallest print a person is able to read rather than fluency. Conventional reading rate tests for educational purposes presents with many limitations; they concentrate on linguistic skills, increase in complexity as the reading progresses, limited by the readers vocabulary but more importantly, they do not take the level of the child's vision into consideration. There is currently no reading rate chart that is designed with optometric notations specifically for children with normal vision and low vision. It is therefore necessary to design a reading rate chart that takes the above limitations into consideration. Aim: This study aimed to design a chart that can be used to measure reading rates in normal sighted and low vision primary school children. Methods: The aim of the study was achieved in four parts; the design, reliability, validity of a reading rate chart and finally the testing of the chart on low vision participants. In the design of the chart, ten frequently used words in grade one English reading books were randomly selected from five primary schools in KwaZulu-Natal province, South Africa. The reliability and validity of the chart were established on normal sighted children, aged nine to twelve years from two primary schools in the Durban area chosen by convenience sampling method, with sample size of 100 for reliability and 100 for validity. Reliability was established with test and retest reading rates using the new chart while validity was established by determining the reading rates using new the chart and the Wilkins reading rate chart. Data were analyzed using the Paired t-test, Pearson correlation, and Bland and Altman method. Finally, the testing of the new chart without and with low vision device, on fourteen low vision children, aged eight to nineteen years, attending a school for the visually impaired in KwaZulu-Natal. Data was analyzed using Paired t-test and Pearson correlation. Results: The words were arranged in random order, ten words per row and ten rows per paragraph. The chart consisted of six paragraphs (versions A, B, C, D, E and F) with six acuity levels and four optometric notations. Each version was printed on a separate sheet, in Arial and Times New Romans fonts and printed in black ink on approximately white cardboards. In reliability, the mean test and retest reading rates were 77.65 ± 25.30 and 78.23 ± 24.70 (p = 0.29, R² = 0.95). In Bland and Altman method, the mean difference was −0.58 with confidence limits at +10.07 and -11.23. In validity, reading rate for Wilkins chart and the new chart were 75.82 ± 23.64 and 74.92 ± 23.58 (p = 0.01, R² = 0.99) respectively. In Bland-Altman method, the mean difference was +0.90, upper limit at +6.33 and lower limit at –4.53. The mean reading rate, of the low vision children, without and with the low vision device were 59.32 ± 24.08 words per minute (wpm) and 67.04 ± 25.63 words per minute (wpm) respectively (p = 0.09 and r = 0.82). Conclusions: This chart can be used for reading rate assessment for both normally sighted and low vision children and is statistically reliable and valid. / Thesis (M.Optom.)-University of KwaZulu-Natal, Westville, 2012.

Darbe, naudojantis informacinėmis technologijomis, sukurta elektroninė informacinė priemonė, nagrinėjanti optinius prietaisus, jų veikimo principus bei panaudojimą praktikoje. Medžiaga pateikiama tinklalapio forma internetinėje svetainėje adresu http://optometrija.3v.lt. / In the work using information technologies an electronic information tool was created, which deals with optical devices, their working principles and use in practice. The material presented in the form of an online website at http://optometrija.3v.lt.