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1.
Purpose
This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting.Methods
Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE® PureMoist® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event.Results
Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r = 8.5 mm, e = 0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions.Conclusions
NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses. 相似文献2.
Michael T.M. Wang Kalaivarny Ganesalingam Chee Seang Loh Trisha Alberquerque Suhaila Al-Kanani Stuti L. Misra Jennifer P. Craig 《Contact lens & anterior eye》2017,40(1):53-58
Purpose
To assess the effects of two weeks of regular phospholipid liposomal spray application on lipid layer grade, tear film stability, subjective comfort, visual acuity, and lipid deposition in silicone hydrogel contact lens wearers.Methods
Thirty-one existing contact lens wearers were enrolled and fitted with two week planned replacement silicone hydrogel contact lenses (Acuvue® Oasys®) in a prospective, randomized, paired-eye, investigator-masked trial. A phospholipid liposomal spray (Tears Again®) was applied to one eye (randomized) four times daily for two weeks. LogMAR high contrast visual acuity (VA), low contrast glare acuity (LCGA), non-invasive tear film break-up time (NIBUT), and lipid layer grade (LLG) were measured at baseline and day 14, in both treated and control eyes. Subjective comfort relative to baseline, and spectrofluorophotometric assessment of contact lens surface lipid deposition were also assessed on day 14.Results
All measurements did not differ at baseline between treated and control eyes. Lipid layer thickness and tear film stability were increased on day 14 in treated eyes (all p < 0.05), but not in control eyes (all p > 0.05). A greater proportion of participants reported improved comfort in the treated eye relative to the control eye (p = 0.002). There were no significant differences in visual acuity or in contact lens surface lipid deposition, between treated and control eyes, on day 14 (all p > 0.05).Conclusion
The phospholipid liposomal spray increased tear film stability, lipid layer thickness and subjective comfort in silicone hydrogel contact lens wearers, without adversely affecting visual acuity or contact lens surface lipid deposition. 相似文献3.
Purpose
To compare vision correction preferences, refractive error, and gender of non-presbyopes and presbyopes.Methods
Adults who wear spectacles or contact lenses completed a survey about refractive correction opinions and refractive error was measured.Results
Of the 304 subjects, 38.2% were presbyopic (≥40 years) and 59.2% were female. Spectacles were the primary vision correction for 78.0% of subjects. Compared to contact lens wearers, the proportion of presbyopes was higher (p = 0.006) in spectacle wearers. There was no difference in the proportion of presbyopes and non-presbyopes who have tried contact lenses (p = 0.2) or who would prefer to wear contact lenses (p = 0.2). In contact lens wearers, there was no difference in the proportion of presbyopes and non-presbyopes with a history of temporary discontinuation (p = 0.9). Within the contact lens wearing group, there was no refractive error difference between presbyopes and non-presbyopes (spherical equivalent p = 0.6; power vector J0 p = 0.5; power vector J45 p = 0.4; anisometropia p = 0.2). Overall, contact lens wearers were more likely to be female (p = 0.004). There was no difference in gender in presbyopic and non-presbyopic contact lens wearers (p = 0.5).Conclusions
Presbyopes and non-presbyopes have similar opinions about spectacles and contact lenses. Presbyopes of all refractive errors prefer contact lens correction when good vision and comfort can be achieved. Eye care providers should not assume that presbyopia, refractive error, or gender are factors that preclude a patient from being interested in contact lens wear. 相似文献4.
Maria Vidal-Rohr James S. Wolffsohn Leon N. Davies Alejandro Cerviño 《Contact lens & anterior eye》2018,41(1):117-121
Aim
Retrospective analysis of different contact lens wearing groups suggests lens surface lubricity is the main factor influencing contact lens comfort. However, the examined commercially available contact lenses differ in material and design as well as surface properties. Hence this study isolates the contribution of lens surface properties using an ultra-thin coating technology.Methods
Nineteen habitual contact lens wearers (21.6 ± 1.7years) wore formofilcon B soft monthly disposable contact lenses with and without coating technology modified surface properties for a month each in a randomised double-masked cross-over study.Objective non-invasive
breakup time (NIKBUT), NIKBUT average and ocular redness (Jenvis grading scale) were evaluated (Keratograph 5M) after 1 week and 1 month of wear. Symptoms were assessed using the Contact Lens Dry Eye Questionnaire (CLDEQ-8); perceived vision quality and subjective lens comfort at insertion, mid-day and end of the day were rated with four Visual Analog Scales.Results
Perceived visual quality (F = 5.049,p = 0.037), contact lens dry eye symptoms (F = 14.408,p = 0.001) and subjective lens comfort (F = 28.447,p < 0.001) were better for coated compared to uncoated lenses. The surface coating postponed the lens dewetting (F = 8.518,p = 0.009) and increased the pre-lens tear film stability (F = 5.626,p = 0.029), but bulbar (F = 0.340,p = 0.567) and limbal (F = 0.110,p = 0.744) redness were similar for both contact lenses. No parameter changed significantly between a weeks’ and months’ wear (p > 0.05). Lens surface wettability and ocular redness were not correlated to changes in symptoms (p > 0.05).Conclusion
As previously hypothesised, enhancing the physical surface properties of a soft contact lens improves subjectively rated wearer comfort, which, in turn, should result in reduced contact lens discontinuation. 相似文献5.
Purpose
Contact lens discomfort remains poorly understood, not least due to lack of associations between clinical signs and symptoms. This study aimed to explore the relationships between osmolarity, comfort and lid wiper epitheliopathy in contact lens wear.Methods
Twenty subjects participated in a randomized, cross-over study where comfilcon A and lotrafilcon A lenses were each worn for 10 days separated by a 7 days washout period. Tear and contact lens osmolarity, ocular symptoms including comfort, tear stability and production, and lid wiper epitheliopathy were measured.Results
Comfort and tear stability decreased and upper lid wiper staining and foreign body sensation increased with lens wear. These were not affected by lens type. A reduction in tear production was seen after 10 days of comfilcon A lens wear. High proportions of lid wiper epitheliopathy were observed at the upper (range 65%–85%) and lower (range 90%–100%) lid margins. Tear and contact lens osmolarity were unaffected by lens wear or type. Contact lens osmolarity was associated with comfort (r = 0.45, p = 0.009). Tear osmolarity moderately correlated with tear stability (r = ?0.53, p = 0.014) and tear production (r = ?0.44, p = 0.012) but not with lid wiper staining.Conclusions
A relationship between comfort and contact lens osmolarity and between tear osmolarity and tear stability and production were found, however, this study was unable to demonstrate an association between comfort and tear osmolarity or lid wiper epitheliopathy. Further studies using contact lenses with a wider range of comfort responses are warranted to investigate these associations further. 相似文献6.
Luigina Sorbara Jyotsna Maram Trefford Simpson Natalie Hutchings 《Contact lens & anterior eye》2018,41(2):193-200
Purpose
First, to examine how wearing high and low modulus lenses with two different base curves affected lens fit, and the corneal tissue and bulbar conjunctival vascular tissue (bulbar redness and blood velocity). Secondly, to quantify the associations between these baseline and outcome variables and the third purpose was to correlate these variables with end of day comfort.Methods
Thirty participants wore higher (PureVision (PV) 8.3, 8.6) and lower (Acuvue Advance (AA) 8.3, 8.7) modulus silicone hydrogel lenses for two weeks on a daily wear basis. Lens fitting characteristics were examined. Corneal epithelial thickness was measured and the cornea and conjunctiva were assessed. RBC velocity was estimated from high magnification bulbar conjunctival images. Subjective comfort/dryness was reported by participants using visual analogue scales.Results
AA lenses were rated the most comfortable (ANOVA, p = 0.041). The least movement was while using the AA 8.3 base curve lens (Tukey p = 0.028). Steep AA and PV lenses showed significantly higher conjunctival staining at the 2 week visit (ANOVA, p = 0.029). There was a significant decrease in RBC velocity with both steeper AA lenses vs PV lenses (Tukey, p = 0.001). Comparing baseline and 2 week visits, there was a significant negative correlation for the PV 8.3 between comfort and superior bulbar staining (r = ?0.53). For both the PV 8.3 and AA 8.3 reduced RBC velocity was correlated with dryness (r = 0.61 and r = 0.91, respectively).Conclusions
Physical differences in contact lenses affect structural and vascular functional aspects of the ocular surface and these may be associated with symptoms of dryness. 相似文献7.
Purpose
To investigate the effect of soft contact lenses (SCL) wearing modality and lens materials on the changes in conjunctival bulbar and limbal redness and conjunctival and corneal staining after two months of SCL wear. Comfort level was also analyzed.Methods
In this longitudinal clinical trial, forty-seven neophyte myopic subjects were fitted with a monthly disposable lens (lotrafilcon-B or comfilcon-A or balafilcon-A) in one eye and a daily disposable lens (nelfilcon-A or stenofilcon-A or nesofilcon-A) in the other eye, randomly selected. Conjunctival bulbar and limbal redness and conjunctival and corneal staining were evaluated before and after lens wear. Effect of lens wearing modality and lens materials on these changes was also determined. Level of comfort was evaluated subjectively twice per day. Comfort level and reduction in end-of-day comfort were compared between different lens wearing modalities and materials.Results
Bulbar and limbal redness and conjunctival and corneal staining were increased (p < 0.001) after lens wear, and changes were similar with daily and monthly disposable lens wear (p > 0.05). Limbal redness was associated with lens materials, and lotrafilcon-B induced the least among the studied lenses (p < 0.05). There was no significant association between the wearing modality and the average comfort level and reduction of end-of-day comfort (p > 0.05).Conclusion
Two months of SCL wear increased conjunctival redness, conjunctival and corneal staining, which were not associated with the lens wearing modality. There was a reduction in end-of-day comfort, similar to daily and monthly lenses. The change in limbal redness and reduction in end-of-day comfort were associated with the characteristics of the lens material. 相似文献8.
Purpose
The aim of this work was to investigate the locus and extent of vitronectin (Vn) deposition on ex vivo contact lenses and to determine the influence of wear modality together with surface and bulk characteristics of the lens material.Methods
The quantity and location of Vn deposition on the surfaces of contact lens materials was investigated using a novel on-lens cell attachment assay technique.Results
Vn mapping showed that deposition resulted from lens-corneal interaction rather than solely from the tear film. Higher cell counts on the posterior surface of the lenses were determined in comparison to the anterior surface. Overall gross Vn deposition was greater for high water content-low modulus materials (117 ± 4 average cell count per field) than low water content-high modulus materials (88 ± 6 average cell count per field).Conclusions
The role of Vn in plasmin regulation and upregulation is widely recognised. The findings in this paper suggest that the locus of Vn on the contact lens surface, which is affected by material properties such as modulus, is potentially an important factor in the generation of plasmin in the posterior tear film. Consequently, the potential for materials to affect Vn deposition will influence lens-induced inflammatory processes. 相似文献9.
10.
Esteban Porcar Juan Carlos Montalt Enrique España-Gregori Cristina Peris-Martínez 《Contact lens & anterior eye》2017,40(3):190-194
Purpose
We describe a case of fitting a corneo-scleral contact lens with a multi-aspheric geometry design (MAGD CScL) on top of a daily silicone hydrogel lens (piggyback system) for keratoconus management.Methods
A 48-year-old man using soft toric contact lenses required an improvement in the unsatisfactory quality of his vision. He presented with bilateral asymmetric keratoconus with high myopia in the right eye (RE) and severe myopia in the left eye (LE). In addition, he had low vision in his LE because of a maculopathy. He was fitted with MAGD CScL to correct his irregular astigmatism. A diagnostic trial set was used in the fitting process and the patient was assessed according to a standardised fitting methodology. Visual acuity, corneal topography and contrast sensitivity were evaluated. The follow-up period was 1 year.Results
The best spectacle-corrected visual acuity was 0.5 logMAR for the RE with ?10 D/-5 D × 60° and 2 logMAR for the LE with ?20 D/-3 D × 105°. After fitting MAGD CScL, visual acuity improved significantly to 0.1 logMAR for the RE and 1.3 logMAR for the LE, as well as contrast sensitivity. The fitting parameters of the base curve, diameter, and power were 7.05 mm, 12.60 mm, ?18.50 D and 7.15 mm, 12.60 mm, ?19 D for the RE and LE, respectively. Optimal fitting characteristics were found in terms of lens position and lens movement. To increase the time of MAGD CScL wear, they piggybacked on daily silicone hydrogel lenses of low power (?0.5 D). The patient reported being comfortable with this piggyback system for approximately 15 h a day. After 1 year of using the piggyback system, visual quality and wearing time were maintained. In addition, no adverse ocular effects were found during this period.Conclusion
This case report shows that in this patient a MAGD CScL could be fitted successfully on a daily silicone hydrogel lens in a piggyback system for keratoconus management, providing good visual quality along with prolonged use times and without adverse effects on the cornea. 相似文献11.
Alejandra Consejo Maciej M. Bartuzel D. Robert Iskander 《Contact lens & anterior eye》2017,40(5):293-300
Purpose
To assess whether short-term soft contact lens wear alters the anterior eye surface.Methods
Twenty-two neophyte subjects wore soft contact lenses for a period of five hours. Topography based corneo-scleral limbal radius estimates were derived from height measurements acquired with a corneo-scleral profilometer. Additionally, central corneal thickness (CCT), anterior chamber depth (ACD), corneal curvature radius (R) and white-to-white (WTW) diameter were acquired with an OCT-assisted biometer. Measurements were obtained without lens wear (baseline), immediately after lens removal following five hours of wear and three hours after lens removal.Results
Short-term soft contact lens wear significantly modifies corneo-scleral limbal radius (mean ± SD: 130 ± 74 μm, p << 0.001) and the changes are repeatable. In contrast, the WTW diameter and R were not modified. ACD and CCT were significantly affected but no significant correlations were found between the increment of the limbal radius and the decrease in ACD and CCT. Limbal radius increment was reversed three hours after lens removal for 68% of the subjects but the time course of this reversal was not uniform.Conclusions
It is possible to accurately quantify limbal radius changes as a consequence of soft contact lens wear. The increment in the limbal diameter could reach over 0.5 mm but that alteration does not correspond to changes in WTW diameter and it was not observable to the examiner using a slit lamp. Assessing topographical limbus after contact lens wear could be a tool to optimize the selection of the contact lens, from the perspective of anterior eye surface changes. 相似文献12.
Qiurong Zhu Bi Yang Nan Deng Yifan Li Tingwei Wang Huang Qi Longqian Liu 《Contact lens & anterior eye》2018,41(2):229-233
Purpose
To assess the prevalence and general knowledge of contact lens wearers among college students in Chengdu, a metroplolitan of Chinaand find out the routine habits of use and hygienic conditions when wearing contact lenses.Method
The questionnaire was distributed to 1,600 ametropic participants who were from 8 different universities. Data about demographics, general contact lens handling habits, personal attitudes, hygiene behaviors and eye health conditions were collected. We made the analysis ofthe demographics and wearing of contact lenses. Possible reasons for behaviors related to the care of contact lenses were analyzed.Results
The prevalence of contact lens use was 19.80%. Most users (82.15%) were females. An aesthetic effect was cited as the first reason for using (57.91%). The comfort of eyes was the first consideration (75.76%) when buying. To keep clean and use safe, 86.20% subjects washed hands before handling and 83.50% cleaned the lens carefully after removing. There was significant difference between males and females regarding the replacement of the solution (p = 0.014). 32.66% wears knew the removal of protein deposits. A total of 54.88% were not informed of the potential complications of contact lens. The incidence of ocular discomfort was 44.78%. Only 3.03% of the students paid regular visits to ophthalmic clinics.Conclusion
The prevalence of contact lenses was relatively low in Chengdu. The wears had limited knowledge about using and careof contact lens. More education on standard lens wear and care should be provided to wearers. 相似文献13.
Debarun Dutta Timothy Zhao Kai Bing Cheah Larke Holmlund Mark D.P. Willcox 《Contact lens & anterior eye》2017,40(3):175-183
Purpose
To determine the antimicrobial activity of the melimine derived peptide Mel4 against Delftia, Stenotrophomonas, Elizabethkingia, Burkholderia and to investigate biocompatibility of Mel4 as an antimicrobial coating on contact lenses in animals and humans.Methods
In vitro antimicrobial activity of Mel4 was determined against the four Gram negative bacteria by investigating growth curves for 24 h followed by viable counts to determine the minimum inhibitory concentration (MIC). Contact lenses were coated by covalently binding Mel4, characterized by amino acid analysis, and were investigated for changes in lens parameters. Safety of Mel-4 coated lenses were determined in a rabbit model of daily contralateral wear. A prospective, randomised, double-masked, contralateral, 1week daily wear human clinical trial was used to evaluate subjective responses and ocular physiology.Results
Mel4 was active against all the bacteria tested (MIC50 ranged from 31–1000 μg ml?1) and produced an antimicrobial surface on contact lenses. Mel4-coating resulted hydrophilic surface without any significant change in contact lens parameters, and showed no signs of cytotoxicity or ocular irritation during rabbit wear. During human clinical trial, there were no differences between Mel4 coated and uncoated contact lenses in lens performance indicators and ocular signs such as corneal fluorescein staining. Mel4 and control uncoated lenses had no differences in ocular symptoms during lens wear.Conclusion
Mel4 has achieved antimicrobial activity against variety of Gram negative bacteria that are often resistant to the action of cationic peptides and have been implicated in contact lens related adverse events. Mel4-coated contact lenses were safe to wear. 相似文献14.
Purpose
To evaluate a novel fitting algorithm for estimation of alignment curve (AC) radius during orthokeratology lens trial.Methods
Fifty myopic children were recruited in this study. AC radii were estimated by both traditional method using flat K readings and eccentricity values and by a novel fitting algorithm, which was composed of 256 circle fittings using corneal elevation data from the corresponding AC region and a succedent toric fitting based on these calculated AC curvatures. Parameters of the final ordered lenses were determined by fluorescein analysis and corneal topography. The number of lens trials was recorded for each patient, and the consistencies of AC radius and astigmatism between the first trial lenses and the final ordered lenses were tested by Pearson correlations and Bland-Altman plots.Results
The numbers of trials for the novel algorithm and traditional method were 1.2 ± 0.4 times vs. 1.8 ± 0.7 times, respectively, and Mann-Whitney test showed significant difference (z = ?3.27, p = 0.001). AC radii of the first trial lenses estimated by the novel fitting algorithm were more close to that of the final ordered lenses, showing a R square value of 0.994 for the fitting algorithm and 0.927 for the traditional method, respectively. Similar results could also be noticed for astigmatism estimation.Conclusion
AC radius and astigmatism of ortho-k lens could be better estimated by two steps of fitting algorithm using corneal elevation data, which may shorten the time needed for ortho-k lens trial and achieve better lens fitting status. 相似文献15.
Objectives
To evaluate the corneal confocal microscopy and dry eye findings in patients with contact lens discomfort.Methods
The study included 3 groups of participants: Contact lens wearers using silicone hydrogel soft contact lenses who are symptomatic (CLD, n = 15) or asymptomatic (ACL, n = 11) and non-wearers as controls (n = 14). Duration of contact lens wear, Ocular Surface Disease Index (OSDI) questionnaire responses, fluorescein tear break-uptime (FBUT), and corneal confocal microscopy findings were recorded.Results
Mean age was 25.7 ± 8.2 years and male/female ratio was 7/33. Demographic findings were similar regarding the groups. CLD patients had a longer lens use history than ACL (median 5 vs 2 years, p < 0.001). OSDI scores were higher in CLD group than ACL or controls (p < 0.001, p = 0.002). FBUT was significantly lowest in CLD group, compared to controls and ACL (p < 0.001, p = 0.039). FBUT was also lower in ACL patients compared to controls (p = 0.036). There was no difference between basal epithelium cell counts between all 3 groups. Anterior stromal activated keratocyte numbers were similar between contact lens using groups but was lower in controls (p = 0.005). However, dendritiform cells in the sub-basal nerve layer were higher in CLD group compared to controls but similar to ACL (p < 0.001, p = 0.058). Graded sub-basal nerve tortuosity was more prominent in CLD group than the ACL (p = 0.014).Conclusion
Patients with CLD had been wearing contact lenses for longer than those without symptoms. OSDI and FBUT scores were worse in CLD patients. In contact lens discomfort patients, there were increased dendritiform cells, indicating intensified inflammatory status of the cornea. 相似文献16.
Anna Sulley Kathrine Osborn Lorenz James S. Wolffsohn Graeme Young 《Contact lens & anterior eye》2017,40(4):248-252
Purose
To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model.Method
A spreadsheet mathematical model was used to calculate fitting SR for various SCL designs. Designs were evaluated using ocular topography data from 163 subjects. The model calculated SR based on acceptable edge strain (within range 0–6%) and horizontal diameter overlap (range 0.2–1.2 mm). Where lenses had multiple base curves (BCs), eyes unsuccessful with the steeper BC were tested with the flatter BC and aggregate SR calculated. Calculations were based on typical, current, hydrogel and silicone hydrogel SCLs and allowed for appropriate on-eye shrinkage (1.0–2.3%). Theoretical results were compared with those from actual clinical trials.Results
Theoretical success rates for one-BC lenses ranged from 60.7% (95% CI 7.2%) to 90.2% (95% CI 3.7%). With two-BC designs, most combinations showed a SR increase with a second BC (84.0%–90.2%). However, one of the two-BC combinations showed only negligible increase with a second BC (72.4%–73.0%). For designs with lower SR, the greatest contributor to failure was inadequate lens diameter. For a given design, differences in shrinkage (i.e. on-eye bulk dehydration) had a significant effect on success rate. In comparison with historical clinical data, there was a positive correlation between small lens fitting prevalence and discomfort reports (r = + 0.95, P = < 0.001) with a poor correlation between theoretical and actual tight/loose fittings.Conclusions
Mathematical modelling is a useful method for testing SCL design combinations. The results suggest that judicious choice of additional fittings can expand the range of fitting success. 相似文献17.
Purpose
This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer.Methods
A prospective, non-randomized control study was performed using an 18 mm scleral lens. They were fitted with a central clearance of 400 um at insertion. One eye was randomly assigned to be fitted with a non-preserved gel solution of carboxymethylcellulose, while the other was inserted with non-preserved saline. Measurements of clearance in 3 locations were taken (OCT) at baseline, every 30 min up to 1h30 post insertion and every 2 h thereafter up to 6h00 of wear. A two-way repeated measure analysis of variance (liquids × times) was used to test central, nasal and temporal fluid thickness.Results
Following 6 h of wear, the 18 mm lens had a mean central settling of 70.0 ± 9.8 μm, 36.7 ± 9.8 μm of which occurred within the first 30 min of wear. There was no significant difference between lenses filled with non-preserved saline to those with non-preserved gel. However, a paired comparison concluded to a significant difference between mean nasal settling (41.4 μm) and temporal settling (20.4 μm).Conclusion
With respect to the lens studied, current results suggest that practitioners can evaluate the lens 30 min post insertion and can estimate the amount of fluid that will remain after lens stabilization by doubling the value obtained initially. The use of non-preserved saline or non-preserved more viscous solution to fill the lens does not influence its settling. 相似文献18.
Stephen J. Vincent David Alonso-Caneiro Michael J. Collins 《Contact lens & anterior eye》2018,41(2):162-168
Purpose
To examine the time course of the reduction in central corneal clearance and horizontal and vertical lens translation (decentration) during miniscleral contact lens wear and the theoretical influence upon the optics of the post-lens tear layer.Methods
Repeated high-resolution OCT images were captured over an 8 h period of miniscleral contact lens wear (using a rotationally symmetric 16.5 mm diameter lens) in 15 young, healthy participants with normal corneae. Central corneal clearance and lens decentration were derived from OCT images using semi-automated image processing techniques.Results
Central corneal clearance decreased exponentially over time, reducing by 76 ± 8 μm over 8 h. Fifty percent of this reduction occurred within 45 min of lens wear and seventy-five percent within 2 h, with thinning of the post-lens tear layer plateauing 4 h after lens insertion. Lens translation exhibited a similar pattern of change (0.18 ± 0.04 mm temporal and 0.20 ± 0.09 mm inferior decentration) stabilising 1.5–2 h after insertion. The change in the lens fit over time resulted in a small reduction in the power of the post-lens tear layer (?0.12 ± 0.01 D) and induced a prismatic effect of 0.01 ± 0.16 Δ base out and 0.50 ± 0.19 Δ base down relative to the pupil centre.Conclusions
For the miniscleral contact lens studied, horizontal and vertical lens decentration followed an exponential decay over 8 h that plateaued approximately 2 h after lens insertion, while central post-lens tear layer thinning plateaued after 4 h of lens wear. 相似文献19.
Purpose
To report a case of lens discontinuation in a long term orthokeratology (OK) lens wearer and describe regression in refraction, corneal topography, and corneal thickness over 408 days after lens discontinuation. Furthermore, the outcome of subsequent LASIK treatment is also reported.Case report
A 41 year old Caucasian female who had been previously wearing OK lenses for 13 years discontinued lens wear in the left eye to consider refractive surgery in that eye. The greatest changes in subjective and objective refractions, corneal topography and thickness occurred during the first 28 days after lens discontinuation. Subjective refraction did not reach baseline values, but corneal topography parameters returned to pre-OK values after 408 days of no lens wear. The patient then received successful refractive surgery treatment in that eye, achieving uncorrected visual acuity of 0.00 LogMAR units, and residual refractive error within ±0.50 D of emmetropia.Conclusion
The period of lens discontinuation required for long term OK lens wearers before refractive surgery is likely to vary between individuals and the patient described in this case report required a significant period of lens discontinuation of at least one year before being considered suitable for refractive surgery. 相似文献20.
Corneo-scleral contact lenses in an uncommon case of keratoconus with high hyperopia and astigmatism
Esteban Porcar Juan Carlos Montalt Enrique España-Gregori Cristina Peris-Martínez 《Contact lens & anterior eye》2017,40(5):351-356