Please use the archived list on the right to look at past peer-reviewed articles.
Bitton,E., Jones,L., Simpson,T., Woods,C. Influence of the blink interval on tear meniscus height in soft contact lens and nonlens wearers. Eye and Contact Lens 2010;36,3:156-163. [ Show Abstract ]
Purpose: Tear meniscus height (TMH) is an indirect measurement of tear film volume. This study investigated the temporal changes in the TMH during the blink interval in the morning (8-9 am) and at the end of the day (5-6 pm) in both soft contact lens (CL) and nonlens wearers (NLW). Methods: Fifty participants (25 CL; 25 NLW) were evaluated for their subjective symptoms, TMH, noninvasive break up time, and bulbar hyperemia at the am and pm visits on the same day. The TMH was measured at set intervals between 2 and 15 sec during the blink interval, using an optical coherence tomographer. Results: The NLW group revealed no changes in a variety of symptoms during the day, whereas the CL group reported an increase in dryness (P=0.03) and grittiness (P=0.02) over the day. For both groups, the TMH and calculated tear meniscus volume revealed lower values immediately after the blink and increased progressively afterwards, mainly due to reflex tearing. The am tear meniscus volume values tended to be higher than the pm values for both groups, but this was not significant (NLW P=0.13; CL P=0.82). Noninvasive break up time deteriorated during the day for both groups but was only significant for the CL group (P=0.002), whereas bulbar hyperemia revealed no statistically significant change for either group. Conclusions: Reflex tearing may play a substantial role in the TMH differences observed over the blink interval. Standardization of the time when a TMH measurement is performed will be valuable in comparing tear film clinical studies. Copyright © Contact Lens Association of Ophthalmologists, Inc.
Boone,A., Heynen,M., Joyce,E., Jones,L. Ex vivo protein deposition on bi-weekly silicone hydrogel contact lenses. Optometry and Vision Science 2010;87,2:146.
Caffery,B., Heynen,M. L., Joyce,E., Jones,L., Robert III,R., Senchyna,M. MUC1 expression in Sjogren's syndrome, KCS, and control subjects. Molecular Vision 2010;161720-1727. [ Show Abstract ]
Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and conjunctival epithelial cells collected from Sjogren's syndrome (SS), non-Sjogren's keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) control subjects. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tears were collected using an eyewash technique. Impression cytology was used to gather protein and mRNA from conjunctival epithelial cells. Soluble and membrane bound MUC1 were quantified via western blotting and MUC1 mRNA was quantified by real time qPCR. Results: The SS group demonstrated significantly higher concentrations of soluble MUC1 (0.12±0.11 [SS]; 0.013±0.02 [KCS; p=0.001]; 0.0023±0.0024 [NDE; p<0.001]) and MUC1 mRNA (3.18±1.44 [SS]; 1.79±1.18 [KCS; p<0.05]; 1.60±0.74 [NDE; p<0.05]) compared to both KCS and NDE groups. Soluble MUC1 expression was also higher in the KCS group compared to the NDE group (p=0.02), where as MUC1 mRNA expression was similar in both KCS and NDE groups. Membrane bound MUC1 expression differed only between the SS and NDE groups (0.005±-0.003 [SS]; 0.003±0.002 [NDE; p=0.002]). Conclusions: These results demonstrate that SS subjects express greater quantities of MUC1 protein and mRNA compared to both KCS and control subjects. Increased soluble MUC1 expression was also found in KCS subjects compared to controls. Membrane bound MUC1 was present in higher concentration in SS versus NDE only. These significant changes in MUC1 expression may represent compensatory or protective responses to chronic insult to the ocular surface. © 2010 Molecular Vision.
Dalton,K., Schneider,S., Sorbara,L., Jones,L. Confocal microscopy and optical coherence tomography imaging of hereditary granular dystrophy. Contact Lens and Anterior Eye 2010;33,1:33-40.
Dumbleton,K., Richter,D., Woods,C., Jones,L., Fonn,D. Compliance with contact lens replacement in Canada and the United States. Optometry and Vision Science 2010;87,2:131-139. [ Show Abstract ]
PURPOSE.: To assess eye care practitioners (ECPs) recommendations for replacement frequency (RF) of silicone hydrogel (SH) and daily disposable (DD) lenses in Canada and the U.S. and to compare noncompliance (NC) with manufacturer recommended RF by the ECP and patient, and the reasons given for NC. METHODS.: Invitations to participate were sent by e-mail to ECPs in Canada and the U.S. Twenty patient surveys were sent to 420 ECPs, and 2232 eligible surveys were received from 216 ECPs (26% Canada, 74% U.S.). Questions related to patient demographics, lens type, wearing patterns, ECP instructions for RF, and actual patient RF. ECPs provided lens information and their recommendation for RF after the surveys were completed and sealed in envelopes. Responses were anonymous. RESULTS.: DD accounted for 18% (Canada) vs. 16% (U.S.) of wearers (p > 0.05); 35% (Canada) vs. 45% (U.S.) wore 2-week replacement SH (2WR; p = 0.011); and 47% (Canada) vs. 39% (U.S.) wore 1-month replacement SH (1MR) lenses (p = 0.025). Thirty-four percent (Canada) vs. 18% (U.S.) of ECPs recommended longer RFs than the manufacturer recommended RF for 2WR lens wearers (p 0.05) and were lowest for DD (13% Canada, 12% U.S.), followed by 1MR (33% Canada, 28% U.S.). The highest NC rates were with 2WR (50% Canada, 52% U.S.). The most frequent reason for NC with 2WR and 1MR was 'forgetting which day to replace lenses' (54% Canada, 53% U.S.) and in DD wearers 'to save money' (56% Canada, 29% U.S., p < 0.001). CONCLUSIONS.: 1MR lenses are more frequently prescribed in Canada. ECPs in Canada were NC with 2WR lenses more frequently than U.S. ECPs, but patient NC rates were the same in both countries for all lens types. ECP and patient NC rates were highest for 2WR lens wearers. Copyright © 2010 American Academy of Optometry.
Dumbleton,K., Woods,C., Jones,L., Richter,D., Fonn,D. Comfort and vision with silicone hydrogel lenses: Effect of compliance. Optometry and Vision Science 2010;87,6:421-425. [ Show Abstract ]
PURPOSE. Silicone hydrogel (SH) lenses are usually replaced after 2 weeks (2W) or 1 month (1M); however, many patients do not comply with the manufacturers' recommended replacement frequency (MRRF). The purpose of this analysis was to investigate the effect of compliance with MRRF on comfort and vision in SH wearers. METHODS. As a part of a larger study investigating compliance with MRRF, patients were asked to rate their subjective comfort and vision from 0 (very poor) to 10 (excellent) in the morning, at the end of the day (EVE), when lenses were new, and needed replacing (NR). RESULTS. One thousand three hundred forty-four patients wore 2W replacement modality (2WR) (n = 717) or 1M replacement modality (1MR) (n = 617) SH lenses. Comfort and vision in the morning and when lenses are new were significantly higher than for EVE and NR (p < 0.001). Twenty-nine percent (95% confidence interval 25.3-32.4) of 1MR and 59% (95% confidence interval 55.5-62.7) of 2WR wearers were non-compliant with the MRRF. Compliance had a significant effect on EVE (p = 0.002, p = 0.008) and NR (p < 0.001, p < 0.001) comfort and vision. After accounting for compliance, EVE and NR comfort and EVE vision were higher for 1MR than 2WR (p = 0.015, p = 0.044, p = 0.019). CONCLUSIONS. Compliant patients had better EVE and NR comfort and vision than non-compliant patients, regardless of replacement modality. Optimal subjective performance with SH lenses seems to be facilitated by replacing lenses as recommended. Copyright © 2010 American Academy of Optometry.
Efron,N., Morgan,P. B., Helland,M., Itoi,M., Jones,D., Nichols,J. J., van der Worp,E., Woods,C. A. Daily disposable contact lens prescribing around the world. Contact Lens and Anterior Eye 2010;33,5:225-227.
Efron,N., Morgan,P. B., Helland,M., Itoi,M., Jones,D., Nichols,J. J., van der Worp,E., Woods,C. A. International rigid contact lens prescribing. Contact Lens and Anterior Eye 2010;33,3:141-143.
Fonn,D. Editorial: Myopia control and new editorial board members. Eye and Contact Lens 2010;36,4:189.
Fonn,D. It's a new day. Eye and Contact Lens 2010;36,3:139.
Fonn,D. Just what do we mean by clinical significance. Eye and Contact Lens 2010;36,1:1.
Fonn,D. Editorial: Concerned parents and patients. Eye and Contact Lens 2010;36,2:67.
Fonn,D. What goes around comes around. Eye and Contact Lens 2010;36,6:323.
Fonn,D., Peterson,R., Woods,C. Corneal staining as a response to contact lens wear. Eye and Contact Lens 2010;36,5:318-321. [ Show Abstract ]
Objective: To review the effects of contact lenses on the corneal surface. Methods: A review of the literature and in-house research of corneal staining and its various forms of presentation. Results: Corneal staining manifests in many different forms. The severity of staining or insult of the cornea is usually determined by the extent (area of coverage), density, and depth. The cause of staining is multifactorial, and its location is often linked to the type of lens that is being worn, the solution used to clean/disinfect the lens, the state of hydration of the soft lens, and the state of the cornea that has been affected by the lens. Conclusions: Sodium fluorescein dye effectively highlights corneal integrity changes referred to as corneal staining. This review describes the manifestations, the cause, the mechanisms, and the methods of remediation of corneal staining. © 2010 Lippincott Williams & Wilkins.
Gorbet,M. B., Tanti,N. C., Jones,L., Sheardown,H. Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions. Molecular Vision 2010;16272-282. [ Show Abstract ]
Purpose: Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. Methods: An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Results: Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of β1 and α3 integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Conclusions: Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells. © 2010 Molecular Vision.
Hall,B. J., Jones,L. Contact lens cases: The missing link in contact lens safety?. Eye and Contact Lens 2010;36,2:101-105. [ Show Abstract ]
Purpose: To summarize a variety of issues associated with contact lens case contamination and discuss appropriate methods that can limit this. Methods: A literature review was undertaken investigating the major factors associated with case contamination, with specific reference to the major pathogens associated with contamination, the role of bacterial biofilms, and methods that can limit contamination. Results: The use of antimicrobial cases, regular case cleaning and case replacement, avoidance of topping up solutions, and not using tap water to rinse cases all appear to be important in avoidance of significant case contamination. Conclusions: Contact lens case contamination is a significant public health concern and may contribute significantly to the development of microbial keratitis in contact lens wearers. Patients should be reminded that they must clean and disinfect their lens cases daily, should avoid the use of tap water for rinsing them, must not top up their solutions, must take into careful consideration where and how the cases are stored during the time that lenses are being worn and that they must be replaced regularly. The adoption of these methods will substantially reduce the levels of contamination of cases with pathogenic microbes. © 2010 Lippincott Williams & Wilkins.
Keech,A., Simpson,T., Jones,L. Repeatability of pachymetry and thinnest point localization using a Fourier-domain optical coherence tomographer. Optometry and Vision Science 2010;87,10:736-741.
Keir,N., Simpson,T., Fonn,D. Visual and optical performance of silicone hydrogel contact lenses for moderate myopia. Journal of Optometry 2010;3,3:149-157. [ Show Abstract ]
Purpose: To compare the short-term visual and optical performance of silicone hydrogel contact lenses for myopia = -3.00D. Methods: This was a short-term, non-dispense, double-masked, randomized study investigating Night&Day (ND), PureVision (PV), O2 Optix (O2), Biofinity (BF), Acuvue Advance (AA) and Acuvue OASYS for myopia = -3.00D. Testing was conducted under scotopic conditions. Measures (one eye only) included: high- and low-contrast visual acuity (HCVA/LCVA), contrast sensitivity, subjective clarity of vision ratings (0-100 scale using reference images, with test image representing grade 50) and ocular aberrations (up to the 4th order, analyzed across individual scotopic pupil sizes). Results: Three males and 27 females participated, with a mean (± SD) age of 24.9 ± 7.7 yrs (range 19 to 53 yrs), sphere of -5.30 ± 1.73D (range -3.00 to -10.75D) and cylinder -0.36 ± 0.23D (range 0 to -0.75D). Mean (± SEM) logMAR HCVA ranged from 0.06 (PV) to 0.10 (AA) (± 0.02), LCVA from 0.33 (BF) to 0.40 (AA) (± 0.02) and contrast sensitivity from 2.33 (BF) to 2.53 (ND) (± 0.15) (differences not statistically significant; all p > 0.05). Subjective ratings for the test image ranged from 59 (PV) to 64 (ND) (± 4) and 56 (AA) to 65 (ND) (± 4), for monochromatic and polychromatic reference images, respectively (all p > 0.05). There was a statistically significant impact on ocular aberrations with all study lenses compared to no lens. Between-lens differences were statistically significant for defocus (Z 0 2), horizontal coma (Z 1 3) and spherical aberration (Z 0 4). Conclusions: Despite some differences in ocular aberrations, there were no significant differences in HCVA, LCVA, contrast sensitivity or subjective ratings across lenses. © 2010 Spanish General Council of Optometry. Published by Elsevier España, S.L. All rights reserved.
Keir,N., Woods,C. A., Dumbleton,K., Jones,L. Clinical performance of different care systems with silicone hydrogel contact lenses. Contact Lens and Anterior Eye 2010;33,4:189-195.
Luensmann,D., Heynen,M., Liu,L., Sheardown,H., Jones,L. The efficiency of contact lens care regimens on protein removal from hydrogel and silicone hydrogel lenses. Molecular Vision 2010;16,10-11:79-92. [ Show Abstract ]
Purpose: To investigate the efficiency of lysozyme and albumin removal from silicone hydrogel and conventional contact lenses, using a polyhexamethylene biguanide multipurpose solution (MPS) in a soaking or rubbing/soaking application and a hydrogen peroxide system (H2O2). Methods: Etafilcon A, lotrafilcon B and balafilcon A materials were incubated in protein solutions for up to 14 days. Lenses were either placed in radiolabeled protein to quantify the amount deposited or in fluorescent-conjugated protein to identify its location, using confocal laser scanning microscopy (CLSM). Lenses were either rinsed with PBS or soaked overnight in H2O2 or MPS with and without lens rubbing. Results: After 14 days lysozyme was highest on etafilcon A (2,200 μg) >balafilcon A (50 μg) >lotrafilcon B (9.7 μg) and albumin was highest on balafilcon A (1.9 μg) =lotrafilcon B (1.8 μg) >etafilcon A (0.2 μg). Lysozyme removal was greatest for balafilcon A >etafilcon A >lotrafilcon B, with etafilcon A showing the most change in protein distribution. Albumin removal was highest from etafilcon A >balafilcon A >lotrafilcon B. H2O2 exhibited greater lysozyme removal from etafilcon A compared to both MPS procedures (p0.62). Albumin removal was solely material specific, while all care regimens performed to a similar degree (p>0.69). Conclusions: Protein removal efficiency for the regimens evaluated depended on the lens material and protein type. Overall, lens rubbing with MPS before soaking did not reduce the protein content on the lenses compared to nonrubbed lenses (p=0.89). © 2010 Molecular Vision.
Luensmann,D., Jones,L. Impact of fluorescent probes on albumin sorption profiles to ophthalmic biomaterials. Journal of Biomedical Materials Research - Part B Applied Biomaterials 2010;94,2:327-336.
Menzies,K. L., Jones,L. The impact of contact angle on the biocompatibility of biomaterials. Optometry and Vision Science 2010;87,6:387-399. [ Show Abstract ]
Biomaterials may be defined as artificial materials that can mimic, store, or come into close contact with living biological cells or fluids and are becoming increasingly popular in the medical, biomedical, optometric, dental, and pharmaceutical industries. Within the ophthalmic industry, the best example of a biomaterial is a contact lens, which is worn by ∼125 million people worldwide. For biomaterials to be biocompatible, they cannot illicit any type of unfavorable response when exposed to the tissue they contact. A characteristic that significantly influences this response is that related to surface wettability, which is often determined by measuring the contact angle of the material. This article reviews the impact of contact angle on the biocompatibility of tissue engineering substrates, blood-contacting devices, dental implants, intraocular lenses, and contact lens materials. Copyright © 2010 American Academy of Optometry.
Menzies,K. L., Rogers,R., Jones,L. In vitro contact angle analysis and physical properties of blister pack solutions of daily disposable contact lenses. Eye and Contact Lens 2010;36,1:10-18. [ Show Abstract ]
Objective: The purpose of this study was to measure the advancing and receding contact angles (CAs) of five daily disposable (DD) lenses and the osmolality, surface tension (ST), and pH of each blister pack solution. Methods: The advancing and receding CAs were measured directly out of the blister pack for five DD lenses: omafilcon A (CooperVision), nelfilcon A (CIBA Vision), modified nelfilcon A (CIBA Vision), etafilcon A (Johnson & Johnson), and narafilcon A (Johnson & Johnson). Advancing CAs were measured using sessile drop and Wilhelmy balance methods. Receding CAs were measured using the Wilhelmy balance method. ST, pH, and osmolality were measured for each blister pack solution from all the DD lenses. Results: The advancing CAs for the nelfilcon A lenses were statistically lower (P<0.05) than the advancing CAs of the other three lenses. The receding CAs for etafilcon A were statistically lower (P<0.05) than the receding CAs for the other four lenses. The pH of all the blister pack solutions was relatively neutral (7.01-7.43). The ST of the blister pack solution for the modified nelfilcon A was significantly lower (P<0.05) than the ST of all other blister pack solutions. The osmolality of the blister pack solutions for the etafilcon A and narafilcon A lenses were significantly higher (P<0.05) than the other blister pack solutions. Conclusions: The modified nelfilcon A lens had low advancing CAs and low receding CAs showing minimal hysteresis. The blister pack solution for the modified nelfilcon A lens had the lowest ST, a low osmolality, and a neutral pH. Copyright © Contact Lens Association of Ophthalmologists, Inc.
Morgan,P. B., Efron,N., Helland,M., Itoi,M., Jones,D., Nichols,J. J., van der Worp,E., Woods,C. A. Twenty first century trends in silicone hydrogel contact lens fitting: An international perspective. Contact Lens and Anterior Eye 2010;33,4:196-198.
Morgan,P. B., Efron,N., Helland,M., Itoi,M., Jones,D., Nichols,J. J., van der Worp,E., Woods,C. A. Demographics of international contact lens prescribing. Contact Lens and Anterior Eye 2010;33,1:27-29.
Papas,E., Wolffsohn,J. S., Jones,L. Innovation in contact lenses: Basic research and clinical science. Journal of Optometry 2010;3,3:123-124.
Peterson,R. C., Fonn,D., Woods,C. A., Jones,L. Impact of a rub and rinse on solution-induced corneal staining. Optometry and Vision Science 2010;87,12:1030-1036. [ Show Abstract ]
Purpose.: To investigate whether the inclusion of a rub and rinse step before contact lens disinfection has an impact on solution-induced corneal staining. Methods.: This was a prospective, double-masked, single investigator study. Twenty participants were recruited for two visits, where balafilcon-A lenses were worn bilaterally for 2 h. Each pair of lenses was prepared using two different methodologies. The "control" lens was transferred from the blister pack directly into a storage case containing polyhexamethylene biguanide-based lens care solution. The contralateral "test" lens was rubbed and simultaneously rinsed using the same polyhexamethylene biguanide-based care solution, for either 60 s (visit 1) or 20 s (visit 2). Both lenses were then soaked in the solution overnight. After baseline corneal staining assessments, the lenses were inserted following a randomized contralateral model. After 2 h, lenses were removed, corneal staining was regraded, and comfort scores were obtained. Results.: Rubbed and rinsed test lenses induced significantly less corneal staining than control lenses for all participants during visit 1 (mean ± SD: 516 ± 843 vs. 2170 ± 902; p 0.05). Conclusions.: Corneal staining induced after 2 h of lens wear with the combination of balafilcon-A and polyhexamethylene biguanide-based lens care solution can be significantly reduced by including a rub and rinse step before overnight soaking. Further work is required to establish the longevity of this effect during the monthly wearing cycle. Copyright © 2010 American Academy of Optometry.
Schulze,M. M., Hutchings,N., Simpson,T. L. The conversion of bulbar redness grades using psychophysical scaling. Optometry and Vision Science 2010;87,3:159-167.
Situ,P., Simpson,T. L. Interaction of corneal nociceptive stimulation and lacrimal secretion. Investigative Ophthalmology and Visual Science 2010;51,11:5640-5645.
Situ,P., Simpson,T. L., Jones,L. W., Fonn,D. Effects of silicone hydrogel contact lens wear on ocular surface sensitivity to tactile, pneumatic mechanical, and chemical stimulation. Investigative Ophthalmology and Visual Science 2010;51,12:6111-6117. [ Show Abstract ]
PURPOSE. To determine the effects of silicone hydrogel lens wear and lens-solution interactions on ocular surface sensitivity. METHODS. Forty-eight adapted lens wearers completed the study, which comprised two phases. Phase 1 included habitual lens wear, no lens wear (7 ± 3 days), and balafilcon A lenses (PV; PureVision; Bausch & Lomb, Rochester, NY) with a hydrogen peroxide-based regimen for 2 weeks; phase 2 included wear of PV with the use of a multipurpose solution containing either polyhexamethylene-biguanide (PHMB) or Polyquad/Aldox (Alcon Laboratories, Fort Worth, TX) preservative, each for 1 week, with a 2-week washout period between solutions. Tactile and pneumatic (mechanical and chemical) stimuli were delivered, and thresholds were determined by Cochet-Bonnet (Luneau Ophthalmologie, Chartres, France) and Belmonte (Cooperative Research Centre for Eye Research and Technology, Sydney, NSW, Australia) pneumatic esthesiometers, respectively. Corneal and conjunctival thresholds and staining scores were assessed at baseline, after 2 and 8 hours of lens wear on day 1 and at the end of each wearing cycle (2 hours). RESULTS. In phase 1, compared to the no-lens baseline, corneal tactile thresholds increased at the 1-day, 8-hour and the 2-week visits (P < 0.05), whereas conjunctival mechanical thresholds decreased at the 1-day, 2-hour and the 2-week visits (P < 0.05). In phase 2, the chemical thresholds were lower with PHMBpreserved solution compared with the Polyquad/Aldox system at the 1-day, 2-hour and the 1-week visits (P < 0.05). Staining scores correlated inversely with conjunctival chemical thresholds (all P < 0.05). CONCLUSIONS. Ocular surface sensitivity changed in adapted lens wearers, when lenses were refit after a no-lens interval and during lens wear with different care regimens. The corneal staining that was observed with certain lens-solution combinations was accompanied by sensory alteration of the ocular surface-that is, higher levels of staining correlated with increased conjunctival chemical sensitivity. © Association for Research in Vision and Ophthalmology.
Sorbara,L., Dalton,K. The use of video-keratoscopy in predicting contact lens parameters for keratoconic fitting. Contact Lens and Anterior Eye 2010;33,3:112-118.
Sorbara,L., Maram,J., Fonn,D., Woods,C., Simpson,T. Metrics of the normal cornea: Anterior segment imaging with the Visante OCT. Clinical and Experimental Optometry 2010;93,3:150-156. [ Show Abstract ]
Purpose: The purpose of the study was to obtain anterior segment biometry for 40 normal eyes and to measure variables that may be useful to design large diameter gas permeable contact lenses that sit outside the region normally viewed by corneal topographers. Also, the distribution of these variables in the normal eye and how well they correlated to each other were determined. Methods: This is a cross-sectional study, in which data were collected at a single study visit. Corneal topography and imaging of the anterior segment of the eye were performed using the Orbscan II and Visante OCT. The variables that were collected were horizontal K reading, central corneal/scleral sagittal depth at 15 mm chord, and nasal and temporal angles at the 15 mm chord using the built-in software measurement tools. Results: The central horizontal K readings for the 40 eyes were 43 ± 1.73 D (7.85 ± 0.31 mm), with ± 95% confidence interval (CI) of 38.7 (8.7 mm) and 46.6 D (7.24 mm). The mean corneal/scleral sagittal depth at the 15 mm chord was 3.74 ± 0.19 mm and the range was 3.14 to 4.04 mm. The average nasal angle (which was not different from the temporal angle) at the 15 mm chord was 39.32 ± 3.07 degrees and the ± 95%CI was 33.7 and 45.5 degrees. The correlation coefficient comparing the K reading and the corneal/scleral sagittal depth showed the best correlation (0.58, p < 0.001). The corneal/scleral sagittal depth at 15 mm correlated less with the nasal angle (0.44, p = 0.004) and the weakest correlation was for the nasal angle at 15 mm with the horizontal readings (0.32, p = 0.046). Conclusion: The Visante OCT is a valuable tool for imaging the anterior segment of the eye. The Visante OCT is especially effective in providing the biometry of the peripheral cornea and sclera and may help in fitting GP lenses with a higher percentage of initial lens success, when the corneal sag and lens sag are better matched. © 2010 The Authors. Journal compilation © 2010 Optometrists Association Australia.
Srinivasan,S., Joyce,E., Boone,A., Simpson,T., Jones,L., Senchyna,M. Tear lipocalin and lysozyme concentrations in postmenopausal women. Ophthalmic and Physiological Optics 2010;30,3:257-266.
Subbaraman,L. N., Jones,L. Kinetics of lysozyme activity recovered from conventional and silicone hydrogel contact lens materials. Journal of Biomaterials Science, Polymer Edition 2010;21,3:343-358.
Varikooty,J., Keir,N., Woods,C. A., Fonn,D. Measurement of the refractive index of soft contact lenses during wear. Eye and Contact Lens 2010;36,1:2-5. [ Show Abstract ]
Purpose: To determine whether the refractive index (RI) of a soft contact lens can be evaluated using refractometry while the lens remains on the eye and to compare this with more traditional ex vivo RI measurements. Methods: A slitlamp apparatus was modified to incorporate a customized Atago hand refractometer. With a double-masked study design, nine adapted symptomatic soft contact lens wearers wore a contact lens in each eye (lotrafilcon B and etafilcon A) in a randomized order. In vivo RI was determined from the relative Brix scale measurements immediately after lens insertion and after 1 and 10 hr of lens wear. Ex vivo refractometry was performed after 10 hr of lens wear for comparison. Means ± standard errors of the means are reported. Results: In vivo RI values at baseline were 1.422 ± 0.0004 (lotrafilcon B) and 1.405 ± 0.0021 (etafilcon A); after 1 hr of lens wear, values were 1.423 ± 0.0006 and 1.408 ± 0.0007, respectively; and after 10 hr of lens wear, values were 1.424 ± 0.0004 and 1.411 ± 0.0010, respectively. Ex vivo RI values at the end of the 10 hr wearing period were 1.424 ± 0.0003 (lotrafilcon B) and 1.412 ± 0.0017 (etafilcon A). The change in in vivo RI across the day was statistically significant for the etafilcon A lens (repeated-measures analysis of variance, P0.05). Conclusions: This novel adaptation of refractometry was able to measure the RI of soft contact lenses during wear (without lens removal). End of day RI measurements using in vivo and ex vivo refractometry were comparable with each other. Future work is required to determine whether this in vivo method can improve our understanding of the relationships between soft contact lens RI, hydration, on-eye lens performance, and symptomology. Copyright © Contact Lens Association of Ophthalmologists, Inc.