Daily disposable soft lens sagittal depth and other lens parameter changes measured at room temperature (20 °C) and on-eye temperature (34 °C).

PURPOSE: To investigate the differences in contact lens sagittal depth (CL-SAG), base curve (BC), and overall lens diameter (OAD) of daily disposable (DD) SCLs at room temperature (20 °C) and on-eye (34 °C) temperature. METHODS: Twelve different spherical daily SCLs were analyzed (labeled power -3.00 D) at 20 °C and 34 °C. The posterior CL-SAG, BC, and OAD were measured directly using a spectral domain OCT-based instrument (Optimec is830). RESULTS: The CL-SAG range for the daily disposable lenses measured at 20 °C was 3468-4016 µm. At 34 °C, the DD CL-SAG of all lenses individually decreased compared to 20 °C (t = 7.78, p < 0.001), ranging from 3385 to 3913 µm. On average at the higher temperature, the measured overall lens diameter was smaller (t = 8.18, p < 0.001) and the BC was marginally steeper (t = 2.11, p = 0.058). CONCLUSIONS: Soft lens parameters change when equilibrated from room temperature (20 °C) to on-eye temperature (34 °C). All lenses shrink when going to on-eye temperature (both lens diameter and CL-SAG decreases), compared to lenses measured at room temperature by ISO standards. Higher water content materials tend to have greater changes to the lens parameters compared to lower water content material lenses.

Impact of multifocal gas-permeable lens designs on short-term choroidal response, axial length, and retinal defocus profile.

AIM: To investigate the impact of multifocal gas permeable contact lens (MFGPCL) in various add power and distance/near area allocation on short-term changes of choroidal thickness (ChT), axial length (AL), and retinal defocus profile in young adults. METHODS: Seventeen young adults (2 males and 15 females; age 23.17±4.48y) were randomly assigned to wear two designs binocularly with a one-week washout period in between. Total of four MFGPCL designs were assessed. All designs were distance-center that varied in two add power (+1.50 and 3.00 D) and/or two distance zone (DZ) diameters (1.50 and 3.00 mm; design A: DZ 1.5/add 3.0, B: DZ 1.5/add 1.5, C: DZ 3.0/add 3.0, D: DZ 3.0/add 1.5). ChT, AL, and peripheral refraction data were collected on each subject at baseline, on days 1 and 7 of MFGPCL daily wear. ChT was assessed in four quadrants using a spectral-domain optical coherence tomography. RESULTS: AL was shortened by -26±44 µm with lens C, -18±27 µm with lens D, -13±29 µm with lens A, and -8±30 µm with lens B (all P<0.05). A significant overall increase in ChT was observed with all 4 designs (lens A: +6±6 µm, B: +3±7 µm, C: +8±7 µm, and D: +8±7 µm). Temporal and superior choroid exhibited more choroidal thickening associated with MFGPCL. All designs induced significant relative peripheral myopia (RPM) beyond the central 20° across the horizontal meridian in both nasal and temporal fields (P<0.05). CONCLUSION: MFGPCLs show a significant influence on ChT and AL, which are associated with significant increase in RPM after short-term wear. The reliability and feasibility of quantifying short-term changes in ChT support its use as a promising marker for the long-term efficacy of myopia-controlling treatments.

Visual performance with multifocal corneal gas-permeable contact lenses in young adults: A pilot study

Objectives: To evaluate the performance of four experimental multifocal gas permeable contact lens (MFGPCL) designs and their impact on visual function in young adults.MethodsSeventeen young adults (age, 23.17 ± 4.48 years) enrolled in the study. Each participant was randomly assigned to wear two of four MFGPCL designs. They wore the first type of the assigned lens binocularly for one week and, after one week of washout period, wore another design on both eyes for another week. The four MFGPCL designs were as follows: design A (distance zone [DZ] 1.5 mm / add 3.0 D), B (DZ 1.5 mm / add 1.5 D), C (DZ 3.0 mm / add 3.0 D), and D (DZ 3.0 mm / add 1.5 D). Baseline visual acuity, contrast sensitivity function, and accommodation data were collected at baseline and repeated after one week of MFGPCL daily wear.ResultsDistance and near visual acuities were not significant affected with the four MFGPCL designs. Contrast sensitivity was significantly lower in design A across all measured spatial frequencies (p < 0.05), with no significant impact from other designs on all frequencies. No significant effect was observed on accommodation measured at 33 cm (p > 0.05).ConclusionsThree of the investigated MFGPCL designs preserve satisfactory visual performance. Lens design A incorporated with higher add and smaller center zone diameter had a stronger impact on the visual performance. (AU)

Visual performance with multifocal corneal gas-permeable contact lenses in young adults: A pilot study.

OBJECTIVES: To evaluate the performance of four experimental multifocal gas permeable contact lens (MFGPCL) designs and their impact on visual function in young adults. METHODS: Seventeen young adults (age, 23.17 ± 4.48 years) enrolled in the study. Each participant was randomly assigned to wear two of four MFGPCL designs. They wore the first type of the assigned lens binocularly for one week and, after one week of washout period, wore another design on both eyes for another week. The four MFGPCL designs were as follows: design A (distance zone [DZ] 1.5 mm / add 3.0 D), B (DZ 1.5 mm / add 1.5 D), C (DZ 3.0 mm / add 3.0 D), and D (DZ 3.0 mm / add 1.5 D). Baseline visual acuity, contrast sensitivity function, and accommodation data were collected at baseline and repeated after one week of MFGPCL daily wear. RESULTS: Distance and near visual acuities were not significant affected with the four MFGPCL designs. Contrast sensitivity was significantly lower in design A across all measured spatial frequencies (p < 0.05), with no significant impact from other designs on all frequencies. No significant effect was observed on accommodation measured at 33 cm (p > 0.05). CONCLUSIONS: Three of the investigated MFGPCL designs preserve satisfactory visual performance. Lens design A incorporated with higher add and smaller center zone diameter had a stronger impact on the visual performance.

Regional Distribution of Choroidal Thickness and Diurnal Variation in Choroidal Thickness and Axial Length in Young Adults.

PURPOSE: To examine the regional distribution of choroidal thickness (ChT) and the diurnal variation in ChT and axial length (AL) over a wide range of myopic refractive error. METHODS: ChT was measured in thirty-four healthy young adults (age mean ± SD: 25.2 ± 2.8, range: 18-35 years) using spectral-domain optical coherence tomography and AL using an IOL-Master 500. Participants were divided into three refractive groups: emmetropes, myopes, and high myopes. We evaluated ChT in macular (foveal, parafovea, and perifovea) and peripheral regions (6-mm from the foveal pit) in four quadrants (superior, temporal, inferior, and nasal). To assess the diurnal variation, three measurement sessions of ChT and AL were taken at 8 AM, 12 PM, 4 PM. RESULTS: ChT thins progressively towards the periphery. Superior and nasal quadrants exhibited the thickest (277 ± 73 µm) and thinnest (218 ± 89 µm) choroid, respectively. Higher myopic eyes showed an overall thinner choroid (237 ± 48 µm) compared to myopic eyes (264 ± 78 µm) (P < 0.05). Higher myopes exhibited a significant choroidal thinning in all quadrants except in the temporal quadrant (all p < 0.05). Both ChT and AL underwent a significant diurnal variation (p < 0.05). The ChT and AL diurnal variation amplitudes in higher myopes were significantly reduced (ChT: 14.6 ± 11, AL: 14.5 ± 13 µm), compared to those in emmetropes (ChT: 21.4 ± 15, AL: 21.3 ± 8.5 µm) and myopes (ChT: 19 ± 17, AL: 19 ± 9.7 µm). Diurnal variation amplitude in ChT did not differ significantly across quadrants and choroidal eccentricity regions (p > 0.05). CONCLUSION: ChT distribution varies based on quadrant and eccentricity; superior choroid exhibited the thickest, and nasal showed the thinnest choroid. Higher myopes experience a reduced diurnal variation in ChT and AL.

Variation in sag values in daily disposable, reusable and toric soft contact lenses.

PURPOSE: While knowledge of the ocular surface sagittal height (OC-SAG) is increasing with newer instrumentation, understanding of soft lens sag values (CL-SAG) in daily clinical practice is limited. This study aimed to report the differences in CL-SAG of a large collection of daily disposable (DD), reusable (2-week and 4-week replacement) and toric lens designs. METHODS: 12 different spherical DD and 15 reusable lens types were analysed (labelled power -3.00D); 17 different toric lens types analysed (6 DD and 11 reusable) in -3.00D =C 0.75 × 180. Posterior CL-SAG was measured directly using a spectral domain OCT-based instrument (Optimec is830). RESULTS: The range in CL-SAG for DDs was 3,398-3,912 microns, for reusable lenses 3,372-4,004 microns and for toric lenses 3,536-4,157 microns. Lens diameter and BC together influence CL-SAG values. For lenses with the same labelled base curve (BC), the maximum difference in the DD group was 264 microns, in the reusable group 418 microns and in the toric group 345 microns. Three lens designs within the DD group and five in the reusable group offer two BCs, with an average variation (±SD) in CL-SAG of 276 ± 39 microns; one toric lens with two BCs showed a 377-micron difference. CONCLUSIONS: Marked differences in CL-SAG values were found in this study, also between lenses of the same BC. While ECPs should be aware that diameter and BC together influence CL-SAG, this also indicates that lens substitution based on BC alone could result in substantial differences in CL-SAG, with a potential impact on lens fit. Lens designs offering two BCs showed a somewhat narrow band in absolute terms in CL-SAG, and switching from a spherical to a toric lens of the same lens manufacturer could result in a significant change in CL-SAG.

An analysis of anterior scleral shape and its role in the design and fitting of scleral contact lenses.

PURPOSE: The purpose of this study was to evaluate the shape of the anterior sclera by measuring the sagittal height and corneoscleral transition angles in the four cardinal and four oblique segments of the eye. MATERIALS AND METHODS: In this study, 78 normal eyes of 39 subjects were evaluated. The sagittal height, corneoscleral angle and scleral angle were measured at three chord lengths (10.0mm, 12.8mm and 15.0mm) in all eight segments of the anterior eye using optical coherence tomography (Zeiss Visante AS-OCT). Scleral toricity was calculated for each eye, defined as the greatest sagittal height difference found between two perpendicular meridians. RESULTS: At a 12.8mm chord length, the shape of the anterior eye was found to be nearly rotationally symmetric, and at a chord of 15.0mm the shape became more asymmetric. The average sagittal heights of the eight segments at a 12.8mm chord ranged from 2890µm to 2940µm; at a 15.0mm chord they ranged from 3680µm to 3790µm. The average scleral angles at a 15.0mm chord ranged from 35.17° to 38.82°. Significant differences between opposing segments were found in the sagittal height and scleral angle measurements at a chord of 15.0mm (sagittal height p≤0.0021; scleral angle p≤0.0105). The nasal measurements revealed flatter scleral angles and concave corneoscleral transitions, whereas temporal scleral angles were steeper, with tangential or convex corneoscleral transitions. CONCLUSION: These findings are important to consider when designing and fitting contact lenses that rest beyond the boundaries of the limbus, such as scleral lenses.

Morphologic changes in cat epithelium following continuous wear of orthokeratology lenses: a pilot study.

PURPOSE: To investigate the sequence of morphologic changes over time in cat epithelium during continuous wear of orthokeratology lenses. METHODS: Four 2-year-old female cats were used; one served as a no lens wear control and three wore custom designed Paragon CRT lenses for myopic and hyperopic correction in the right and left eyes, respectively. Lenses were worn continuously and animals were euthanased after 4h, 8h and 14 days. Corneal tissue was fixed then stained with hematoxylin and eosin for histologic evaluation and measurement of epithelial thickness. RESULTS: Average epithelial thickness of control eyes in the centre (38+/-1 microm) and mid-periphery (3.0 mm from the centre, 38+/-2 microm) of the cornea was similar. Epithelial thickness in myopic corrected eyes showed progressive thinning in the centre and progressive thickening in the mid-periphery with increased lens wearing time. Hyperopic corrected eyes showed the opposite pattern of progressive epithelial thickening in the centre and thinning in the mid-periphery with lens wearing time. CONCLUSIONS: The epithelium appears to play a major role in the changes induced by orthokeratology lenses. The epithelial effects were dependent on time and lens design. Further studies are needed to determine the mechanisms responsible for these changes.

The current state of corneal reshaping.

PURPOSE: The application of contact lenses to alter the shape of the cornea and temporarily reduce or eliminate myopia is known as orthokeratology, corneal refractive therapy, or corneal reshaping. It was first introduced in the 1960s, but high oxygen permeable materials and more sophisticated designs allow patients to wear contact lenses only during sleep, while dramatically improving the predictability and rate of myopia reduction. Many studies have shown that most corneal reshaping patients achieve uncorrected visual acuity of 20/25 or better that lasts all day long in one to two weeks of nighttime wear. Treatment is primarily effective through central epithelial thinning and midperipheral epithelial and stromal thickening. Much remains to be learned about corneal reshaping contact lenses and their effects on the cornea. METHODS: The authors reviewed existing knowledge and determined what needs to be learned in order to provide patients with appropriate informed consent prior to corneal reshaping contact lens wear. RESULTS: While corneal reshaping contact lenses are effective at temporarily reducing or eliminating myopia, claims about the progress of myopia being controlled with corneal reshaping contact lenses should not be made until further studies are published in peer-reviewed literature. The incidence and prevalence of microbial keratitis related to corneal reshaping contact lens wear is not known. Any overnight wear of contact lenses increases the risk of infection, but it is not known whether the risks of microbial keratitis are greater for corneal reshaping overnight contact lens wearers than other form of overnight contact lens wear. It is also not known whether the risk of microbial keratitis is greater for children than adults, but we must determine if children are at greater risk than adults because many children are wearing corneal reshaping contact lenses. CONCLUSIONS: Finally, it is recommended that ongoing education be provided to practitioners and staff regarding safety, informed consent, and prevention of potential problems, with special emphasis on the critical need to properly and thoroughly disinfect lenses that will be worn overnight.

Bacterial populations on silicone hydrogel and hydrogel contact lenses after swimming in a chlorinated pool.

PURPOSE: A number of reports have indicated an association between swimming with contact lenses and subsequent eye infection. This study tests whether a hydrophilic contact lens worn while swimming accumulates bacteria present in the water. It was of interest to determine whether lens type (silicone hydrogel vs. hydrogel) affected the result. METHODS: Fifteen healthy noncontact lens wearers swam for 30 minutes with a silicone hydrogel lens (PureVision, Bausch & Lomb, Rochester, NY) on one eye and a hydrogel lens (Acuvue 2, Vistakon Inc., Jacksonville, FL) on the other. Lenses were removed aseptically and placed in sterile vials 10 minutes after the subjects left the water. Microbial growth was enumerated for total numbers of colonies and categorized by species present. Numbers of colonies were compared between the two lens groups and with a water sample taken from the pool at the time of the experiment. Eight of the subjects returned on a different day and wore new lenses for 50 minutes in normal room conditions. RESULTS: Two lenses were lost while swimming. Twenty-seven of the remaining 28 lenses worn while swimming showed colonization, principally with Staphylococcus epidermidis, which was also by far the most common species identified from the water itself. Small numbers of Staphylococcus aureus and Streptococcus salivarius were also present in the water and on the lenses. Numbers of colonies varied among subjects (range, 0 to 230), but no differences were observed between the two lens groups. Lenses removed after 30 minutes of wear without swimming were mostly sterile, with 3 of 16 lenses showing just two colonies each. CONCLUSION: It appears that wearing a hydrophilic lens while swimming allows accumulation of microbial organisms on or in the lens, regardless of lens material. Swimmers should be advised to wear tight-fitting goggles if lenses are worn while swimming, and thorough disinfection of the lenses before overnight wear seems prudent.

The effect of add power on distance vision with the acuvue bifocal contact lens.

PURPOSE: This study was designed to determine if subjective evaluation of quality of distance vision with the Acuvue Bifocal contact lens could be correlated with high- and low-contrast acuity scores. METHODS: LogMAR visual acuities of 20 non-presbyopic subjects were measured using high and low-contrast Bailey-Lovie charts. Each subject wore an Acuvue Bifocal contact lens with add powers +1.00, +1.50, +2.00, and +2.50, each optimized for best distance acuity. RESULTS: Subjects showed significantly decreased acuities with increasing add; a low-contrast target heightened this effect. Subjects reported a reduction in quality of distance vision, increasing fluctuation, ghosting/shadows, and halos around lights that correlated with increasing add power. CONCLUSIONS: Our findings suggest that the Acuvue Bifocal contact lens may be expected to perform best for presbyopes with low-to-moderate bifocal add requirement, and that clinicians should anticipate decreased low-contrast acuity and reduced overall quality of vision as add powers are increased.

Modern corneal reshaping with contact lenses.

The renaissance of corneal reshaping has been influenced dramatically by new lens designs, high-oxygen permeable materials, and corneal mapping techniques. These evolutionary advances have dramatically changed the practitioner's view of the modality. The procedure has evolved from a specialty practiced by only a handful of practitioners to a technique that can be incorporated successfully into almost any eye care practice.