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Lens Wear (lens + wear)
Kinds of Lens Wear Selected AbstractsThe effect of treatment zone diameter in hyperopic orthokeratologyOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2009Paul Gifford Abstract Purpose:, To investigate the time course of treatment zone (TZ) diameter changes in hyperopic orthokeratology (OK) lens wear from 1 h in the open eye through to seven nights in the closed eye. Methods:, Twelve subjects were fitted with rigid hyperopic OK lenses. Lenses were worn in the open eye for 1 h then one night in the closed eye, separated by a washout period of 4 days. Changes in best corrected visual acuity (BCVA) and corneal topography (Medmont E-300) were measured on lens removal. The TZ, comprising the central steepened zone (CSZ) and surrounding annular flattened zone (AFZ), was measured from corneal topography. Subsequently, ten subjects wore the same lens design overnight for seven nights, and measurements were taken on lens removal and 8 h later on Days 1 and 7. Results:, Both CSZ and AFZ were apparent after 1 h of hyperopic OK lens wear. CSZ decreased while AFZ increased with longer periods of lens wear. BCVA reduced with longer periods of lens wear and was associated with decreasing CSZ (r = ,0.866, p < 0.001) and increasing AFZ (r = 0.447, p < 0.05). Conclusions:, The association of changes of treatment zone size with reductions in BCVA suggests that increasing CSZ may lead to better visual outcomes in hyperopic OK. [source] Spectral optical coherence tomography: a new imaging technique in contact lens practiceOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2006omiej J. Ka Abstract Purpose:, Spectral optical coherence tomography (SOCT) is a new non-invasive, non-contact, high-resolution technique, which provides cross-sectional images of objects that weakly absorb and scatter light. The aim of this article is to demonstrate the application of SOCT to imaging of eyes fitted with contact lenses. Methods:, Nine eyes of six different subjects fitted with various contact lenses have been examined with a slit-lamp and a prototype SOCT instrument. Results:, Our SOCT system provides high-resolution (4,6 ,m longitudinal, 10 ,m transversal) tomograms composed of 3000,5000 A-scans with acquisition time of 100,250 ms. The quality of the images is adequate for detailed evaluation of contact lens fit. Design, shape and lens edge position were assessed, and complications of contact lens wear could be visualized. Thickness of the lens, corneal epithelium and stroma as well as the space between the lens and the eye surface have been measured. Conclusions:, SOCT allows high-resolution, cross-sectional visualization of the eye fitted with a contact lens. The ability to carry out a detailed evaluation of the fitting relationship between the lens and the ocular surface might be useful in research and optometric practice. SOCT can also be helpful in diagnosis, evaluation and documentation of contact lens complications. [source] Infectious keratitis related to orthokeratologyOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2006Xuguang Sun Abstract Purpose:, To report 28 cases of infectious keratitis related to orthokeratology lens overnight wear in China. Methods:, From March 2000 to August 2001, 28 cases of infectious keratitis related to overnight orthokeratology lens wear were diagnosed in Beijing Institute of Ophthalmology. These were retrospectively reviewed with regard to the pathogens isolated, duration of wear, the time since onset of symptoms, and age. Cultures of corneal scrapes for bacteria, fungus and Acanthamoeba were performed in all of the 28 cases. Results:, All cases were students, including 10 males and 18 females, average age was 16 years (range 10,21 years). The duration of orthokeratology overnight wearing was from 2 weeks to 2 years. Uncorrected visual acuity (UCVA) on initial examination in our institute was from 20/200 to light perception. Of 28 isolates, 24 were culture positive (including 11 bacteria, 11 Acanthamoeba and two fungi), and four were culture negative. In two of the four culture negative cases, Acanthamoeba cysts were detected in the corneal stroma with the confocal microscope. Acanthamoeba and Pseudomonas aeruginosa accounted for 75% (21 of 28) of the cases of infectious keratitis. Conclusion:, Infectious keratitis is a severe complication associated with overnight orthokeratology lens wear. Ophthalmologists should pay more attention to this complication in practice. [source] Incidence of corneal pigmented arc and factors associated with its appearance in orthokeratology,OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2005Pauline Cho Abstract Purpose:, To determine the incidence of the corneal pigmented arc in orthokeratology (ortho-k) lens wearers over 12 months of lens wear and the factors associated with its appearance. Method:, Thirty-five ortho-k subjects were recruited; refractive and corneal changes after lens wear (single-lens protocol) were monitored over 12 months. The incidence of the pigmented arc after 3, 6 and 12 months of lens wear was determined. Results:, The incidence of corneal pigmented arc was 17% (27%), 49% (49%) and 90% (93%) after 3, 6 and 12 months lens wear respectively in the left and right eyes. For subjects with arcs observed in the left eye within the first 6 months of lens wear, the mean ± S.D. period of lens wear before initial detection of the arc was 14 ± 7.4 weeks, and no correlation was found between this factor and the baseline spherical and cylindrical refractive errors (i.e. refractive sphere and cylinder, respectively), spherical equivalent refractive error (SERE), the target myopia reduction, the amount of refractive sphere (or SERE) reduction and changes in central and peripheral corneal curvatures after 6 months of lens wear. Baseline refractive sphere, baseline SERE, target, amount of myopia reduction, and change in central corneal curvature were significantly larger (p < 0.05) in those subjects with pigmented arcs after about 6 months of lens wear. The intensity of the observed pigmented arcs after about 6 months of lens wear was significantly related to the time when it was first observed (p = 0.003). Significant correlation was also found between the intensity of the arcs and the following parameters: baseline refractive sphere and SERE, target, change in central corneal curvature, and amount of myopia reduction (p < 0.006). After about 12 months of lens wear, the intensity of observed arcs was significantly related to the baseline refractive sphere, SERE and the target (p < 0.006). Conclusion:, The incidence of ortho-k-associated pigmented arc increases from 17% after 3 months of lens wear to over 90% after 12 months of lens wear. The intensity of the arc is related to the time when the arc first appeared. Both the incidence and the intensity of the arc are related to the period of lens wear, baseline refractive sphere, SERE and the target. [source] The ChromaGen contact lens system: colour vision test results and subjective responsesOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2001Helen A. Swarbrick Summary The ChromaGen lens system is designed to enhance colour perception in colour vision deficiency (CVD). To investigate its efficacy, 14 CVD subjects were prescribed ChromaGen contact lenses. Colour vision tests (Ishihara, Farnsworth Munsell D-15, Farnsworth Lantern) were administered at baseline, lens dispensing, and after a 2-week lens-wearing trial during which subjective responses were recorded daily using visual analogue scales. ChromaGen lenses significantly reduced Ishihara error rates(p<0.001; ANOVA), particularly for deutan subjects. There was also a significant reduction in errors(p<0.005) on the D-15 test. Conversely, lens wear had no significant effect on Farnsworth Lantern test performance. Subjectively, subjects reported enhanced colour perception, but poor vision in dim light. Judgement of distance and motion were only slightly affected. We conclude that ChromaGen lenses may enhance subjective colour experience and assist in certain colour-related tasks, but are not indicated as an aid for CVD in occupations with colour vision-related restrictions. [source] 2167: Tear film biomarkers as prognostic indicators for recurrent pterygiumACTA OPHTHALMOLOGICA, Issue 2010N ZAKARIA Purpose The aim of this project is to establish the use of IL-6, IL-8 and VEGF as biomarkers in the tear film for early detection of recurrent pterygium. Methods Cytometric Bead Array (CBA) kits will be used to perform multicytokine assays in the tear samples of eyes having pterygium before and after surgical resection of the pterygia. This technique utilizes flow cytometry to determine the concentrations of multiple analytes namely IL-6, IL-8 and VEGF (proposed biomarkers) present in small volumes of tear fluid.Patients with pterygia showing corneal encroachment and requiring surgical excision will be recruited in this study along with a second population of control subjects consisting of individuals with no history of eye diseases or contact lens wear. After instilling a local anesthetic, 3 drops of normal saline will be applied and the at least 50µl of the diluted epithelial secretions collected and stored at -80°C for CBA analysis. From the results we can determine the baseline levels of IL-6, IL-8 and VEGF present in normal epithelial secretions and correlate it with potentially higher levels in the eyes of patients with pterygia. By collecting post op epithelial secretions at different time points along with regular ocular surface photographs and grading of any recurrent pterygia we will be able to ascertain the role of these cytokines and growth factors as biomarkers for recurrent pterygia. Conclusion By establishing higher tear film levels of IL-6, IL-8 and VEGF in eyes with pterygia compared to normal eyes and the return to baseline levels post excision we can begin to ascertain the role of these key players in the pathogenesis of pterygia. [source] An epidemiologic analysis of staphylococcus aureus-associated keratitis in BostonACTA OPHTHALMOLOGICA, Issue 2009I BEHLAU Purpose S. aureus is a normal commensal of the human skin and nasopharynx. It is therefore of interest to determine whether S. aureus keratitis is caused by a subset of these organisms. In this study, the phenotypic and genotypic characteristics of S.aureus keratitis isolates were analyzed. Methods All S. aureus clinical isolates were prospectively collected over a 24 month period at the MEEI (2006-2008). The diagnosis of clinical keratitis and associated risk factors was by medical record review. Keratitis-associated S. aureus strains were assessed for: 1) antibiotic susceptibility, 2) biofilm robustness by gentian violet staining using an in vitro microtiter plate assay, and 3) genetic lineage by multi-locus sequence typing (MLST). Results 26 cases of keratitis were identified from the 600 S. aureus clinical isolates. Risk factors associated with S.aureus keratitis included trauma, prior surgery, soft contact lens wear, and the presence of a foreign body. Ocular surface disease does not appear to be an independent risk factor. All 26 isolates were tetracycline- and trimethoprim-sulfamethoxazole- sensitive. All the MRSA strains were found to be ciprofloxacin-resistant (10/26). Nearly one-half of all the S.aureus keratitis-associated isolates were caused by a single clone, ST5. Both methicillin sensitive and resistant S. aureus strains were represented within ST5. Conclusion These results suggest that there may be specific S.aureus lineages which possess phenotypic and genotypic characteristics that enable S. aureus to more effectively cause sight-threatening keratitis. Future work will examine their virulence traits and a comparison to commensal S.aureus strains. [source] Contact lens induced keratitis associated with contact lens wearACTA OPHTHALMOLOGICA, Issue 5 2001Irene Dejaco-Ruhswurm ABSTRACT. Purpose: To evaluate clinical characteristics, risk factors, management and outcome of contact lens induced keratitis (CLIK) associated with contact lens wear. Methods: The study comprised all consecutive patients presenting with contact lens related presumed microbial keratitis during a 12-month period at our department. Detailed demographic data, type of contact lens, duration of lens wear, wearing schedule and lens hygiene were derived from a self-administered questionnaire. Severity of ulcer, corneal scrapings, treatment and final outcome were evaluated. Results: 27 patients with CLIK, some of which may have been sterile peripheral infiltrates, due to contact lens wear were detected. In the majority of the cases patients had used disposable soft contact lenses (89%) and most of them had a daily wearing schedule (78%). 51.8% patients cleaned their lenses regularly. 6 (22%) applied no disinfection since their lenses were disposable on removal. In 3 of our cases with CLIK, penetrating keratoplasty had to be performed. Conclusion: Disposable contact lenses seem to have been a predisposing factor for contact lens induced keratitis also when used on a daily wear schedule. Insufficient contact lens care products and/or manufacturing characteristics may be responsible for CLIK, which is also observed in otherwise compliant contact lens users. In 3 of our patients with CLIK keratoplasty became necessary, indicating that contact lens induced keratitis may result in severe corneal complications. [source] Allergic Conjunctivitis and Contact Lenses: Experience with Olopatadine Hydrochloride 0.1% TherapyACTA OPHTHALMOLOGICA, Issue 2000M. Brodsky ABSTRACT. Objective: The efficacy of Patanol®, a topically applied anti-allergic agent, was evaluated in a group of patients with allergic conjunctivitis due to contact lens wear (GROUP I) and a group comprised of seasonal allergic conjunctivitis patients, vernal conjunctivitis patients and atopic keratoconjunctivitis patients (GROUP II). Methods: One drop of Patanol® was administered to each eye twice daily. Signs and symptoms were assessed 7, 14, and 28 days after initiation of drug therapy. Results: Itching/burning, tearing, hyperemia and papillary reaction were reduced to scores of 0/1 (absent/mild) in 85%, 90%, 81% and 62%, respectively, of GROUP I patients at Day 28. The allergic conditions in GROUP II patients also improved with Patanol® treatment. Itching/burning, tearing, hyperemia and papillary reactions were absent/mild in 60%, 76%, 96% and 90%, respectively, of these patients at Day 28. Conclusion: Patanol® treatment effectively and rapidly alleviated the signs and symptoms of allergic conjunctivitis due to contact lens wear as well as vernal conjunctivitis, atopic keratoconjunctivitis and the common seasonal allergic conjunctivitis. Patanol® allowed allergic patients to be more comfortable while permitting them to continue using contact lenses. [source] In vivo confocal microscopy of the bulbar conjunctivaCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 4 2009Nathan Efron PhD DSc Abstract Background:, The aim of this work is to develop a more complete qualitative and quantitative understanding of the in vivo histology of the human bulbar conjunctiva. Methods:, Laser scanning confocal microscopy (LSCM) was used to observe and measure morphological characteristics of the bulbar conjunctiva of 11 healthy human volunteer subjects. Results:, The superficial epithelial layer of the bulbar conjunctiva is seen as a mass of small cell nuclei. Cell borders are sometimes visible. The light grey borders of basal epithelial cells are clearly visible, but nuclei can not be seen. The conjunctival stroma is comprised of a dense meshwork of white fibres, through which traverse blood vessels containing cellular elements. Orifices at the epithelial surface may represent goblet cells that have opened and expelled their contents. Goblet cells are also observed in the deeper epithelial layers, as well as conjunctival microcysts and mature forms of Langerhans cells. The bulbar conjunctiva has a mean thickness of 32.9 ± 1.1 µm, and a superficial and basal epithelial cell density of 2212 ± 782 and 2368 ± 741 cells/mm2, respectively. Overall goblet and mature Langerhans cell densities are 111 ± 58 and 23 ± 25 cells/mm2, respectively. Conclusions:, LSCM is a powerful technique for studying the human bulbar conjunctiva in vivo and quantifying key aspects of cell morphology. The observations presented here may serve as a useful marker against which changes in conjunctival morphology due to disease, surgery, drug therapy or contact lens wear can be assessed. [source] Bacteria commonly isolated from keratitis specimens retain antibiotic susceptibility to fluoroquinolones and gentamicin plus cephalothinCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 1 2006Cameron N Ly MB BS Abstract Purpose:, Patients presenting with presumed infective keratitis were studied to determine predisposing factors, the current susceptibilities of the bacterial isolates to a range of relevant antibiotics, the success rate of topical antibiotic treatment of keratitis and predictors of failure of topical therapy. Methods:, Corneal scrapings taken from patients who presented between January 2002 and December 2003 to the Sydney Eye Hospital Emergency Department with keratitis were cultured. The minimum inhibitory concentration of selected antibiotics was determined for each bacterial isolate using an agar dilution technique. Results:, One hundred and twelve consecutive patients presented with corneal ulcers. Forty-seven of the 112 (42%) patients had a growth from the corneal scraping. Potential predisposing factors were identified in 64% of patients, most frequently contact lens wear (36% of patients). Coagulase-negative staphylococci were the most common species isolated. Other common organisms isolated include Pseudomonas aeruginosa, Corynebacterium spp., Staphylococcus aureus and Streptococcus spp. Conclusions:, Most microorganisms isolated from patients with bacterial keratitis showed susceptibility to ciprofloxacin and aminoglycosides. Cephalothin plus aminoglycoside constituted an effective initial broad-spectrum antibiotic combination. The success rate of topical antibiotic treatment of corneal abscess is 89%. Predictors of failure include older age group, medium or large ulcer, culture-negative keratitis, hypopyon and poor visual acuity. [source] Contact lens management of infantile aphakiaCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 1 2010Richard G Lindsay BScOptom MBA FAAO (DipCL) FCLSA FVCO The visual outcomes for infants 18 months or younger with cataracts have improved dramatically over the past couple of decades. Earlier detection of infantile cataract and prompt surgical removal,with subsequent visual rehabilitation with contact lenses,mean that these patients now have a much better visual prognosis. Advances in contact lens technology have led to a significantly higher success rate with contact lenses and this has been a major factor in improving the visual outcomes for aphakic infants. This review outlines the contact lens management of infantile cataract, including a detailed analysis of the various contact lens options available and a discussion regarding the important factors that can cause issues with contact lens wear and affect the overall visual rehabilitation of the infant. [source] Sensory ocular dominance based on resolution acuity, contrast sensitivity and alignment sensitivityCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 1 2009Catherine Suttle PhD MCOptom Background:, Ocular dominance is the superiority or preference of one eye over the other in terms of sighting, sensory function (for example, visual acuity) or persistence in binocular rivalry. There is poor agreement between sighting and sensory dominance and findings are equivocal on the possible neural basis of ocular dominance and its significance. Thus, there are questions on the meaning and importance of ocular dominance. Despite the lack of clarity in this area, ocular dominance is used clinically, for example, as the basis for decisions on monovision in contact lens wear and on treatment of anomalies of binocular vision. Methods:, Sighting dominance and three types of sensory dominance (based on resolution acuity, contrast sensitivity and alignment sensitivity) were compared within individuals, with the main aim of determining whether sensory dominance is consistent across spatial visual functions. Results:, Our findings indicate that each type of sensory dominance is insignificant in most individuals and in agreement with previous work that sensory and sighting dominance do not generally agree. Conclusion:, These results demonstrate not only that different types of ocular dominance are not in agreement but also that in the normal visual system sensory dominance as measured here is insignificant in most individuals with normal vision. [source] | ||||||||||