REGIONAL VARIATION IN FLUID RESERVOIR THICKNESS, OXYGEN TRANSMISSIBILITY AND CORNEAL OEDEMA DURING SCLERAL LENS WEAR

Purpose: To determine if regional variation in post lens fluid reservoir thickness (PLFT) during scleral lens wear leads to regional variation in oxygen transmissibility and corneal edema during 4 hours of non-fenestrated scleral lens wear.Methods: About 20 healthy subjects (mean age, 28.8 ± 4.2 years) were fitted with nonfenestrated rotationally symmetric scleral lenses. Anterior segment optical coherence tomography was used to measure cornea thickness before and after lens wear, PLFT 10 minutes and 4 hours after lens application, and scleral lens thickness (with the scleral lens in situ) 4 hours after scleral lens application. These measurements were limited to the central 6 mm and divided into three zones (central, mid-peripheral, and peripheral zones). In the mid-peripheral and peripheral zones, eight principal meridians were measured, generating 17 measurement points in total. Scleral lens thickness and PLFT measurements were corrected for optical distortions by a series of equations. Oxygen transmissibility was calculated by dividing the scleral lens oxygen permeability by the optically-corrected scleral lens thickness, taking into account the oxygen permeability of saline and fluid reservoir thickness.Results: A significant regional variation in PLFT (F = 12.860, P = 0. 012) was observed after 10 minutes of the lens application, PLFT was thickest and thinnest in the inferotemporal and the superonasal region of the peripheral zones( 322.6 ± 161.8 µm and 153.8 ± 96.4 µm, respectively); however, this variation was not statistically significant at 4 hours of scleral lens wear (F = 4.692; P = 0.073). Despite significant regional variation in oxygen transmissibility (F = 48.472; P = 0.001) and relatively low oxygen transmissibility through the scleral lens, induced corneal edema did not vary significantly in different regions (F = 3.346; P = 0.126). In the central corneal region, the induced corneal edema correlated moderately with PLFT (r = 0.468; P = 0.037) and oxygen transmissibility (r = -0.528; P = 0.017). This relationship was insignificant in the peripheral cornea.Conclusion: The inferotemporal peripheral region had the thickest PLFT and least oxygen transmissibility, and the superonasal region had the vice versa. Despite significant variation in PLFT and oxygen transmissibility initially, in healthy corneas, this variation does not seem to induce statistically significant regional variation in corneal edema. Increased central PLFT and decreased oxygen transmissibility moderately correlate with central corneal edema.

MICROBIAL BIOBURDEN OF ORTHOKERATOLOGY AND HYDROGEL CONTACT LENSES AND STORAGE CASES USING A HYDROGEN-PEROXIDE DISINFECTING SYSTEM

Background and objective: The fitting of orthokeratology (ortho-k) and multifocal soft contact lenses (SCL) is becoming increasingly popular worldwide for reducing the rate of myopia progression. However, overnight wear use of lenses and microbial contamination of contact lenses and storage vials has been shown to increase the risk of corneal inflammatory and infiltrative events (CIEs). Therefore, we conducted a pilot study to compare the rate, level, and type of microbial contamination of contact lenses and storage vialswhen participants wear ortho-k and SCL in combination with a hydrogen-peroxide disinfecting system. Material and Methods: A prospective, single-centre, randomized, crossover study was conducted to evalu-ate the rate and level of contact lens and storage vials contamination during the use of ortho-k and SCL along with a hydrogen-peroxide disinfecting solution over two 10 day wearing periods. Ocular signs and symptoms were assessed during lens wear at baseline and after each wearing period. In addition, contact lens and storage vials were collected, and the type and amount of microbial contamination were evaluated using viable culture and standard identification methods.Results: Twenty-five adults were enrolled, and 21 completed the study. One (5%) ortho-k lens, five (24%) ortho-k storage vials, one (5%) SCL and one (5%) SCL storage vial were contaminated (P > 0.05), predominantly with Gram-positive bacteria. None of the participants had contamination with both ortho-k and SCL. No significant differences were found between the ocular signs, including conjunctival redness and roughness, or conjunctival or corneal staining (all P > 0.05), irrespective of using ortho-k or SCL. Conclusion: This study provides the first data that directly compares microbial contamination of ortho-K versus SCL in patients using a hydrogen-peroxide disinfection system. However, the overall microbial contamination rate of contact lens storage vials was much lower (30%) than the previously reported study with ortho-k lens wear. The results support conducting a larger clinical trial designed to understand differences in microbial contamination with different lens materials and modalities.

REPRODUCIBILITY OF MEASUREMENTS OF PRE-CONTACT LENS TEAR FILM KINETICS UNDER NORMAL AND ADVERSE ENVIRONMENTAL CONDITIONS

Objectives: To evaluate the reproducibility of tear film kinetics (TFK) measurements during the full interblink period in habitual wearers of delefilcon A daily disposable contact lenses under different environmentalconditions.Methods: Two independent studies were performed, one involving 90 eyes measurements in 49 subjects and the second involving 58 eyes measurements in 32 subjects, after 3 hours of conventional wear in normal environmental conditions (NEC) and an additional 3 hours of computer use under adverse environmental conditions (AEC), defined as 20% relative humidity (RH). Digital videos were obtained by non-invasive Tearscope illumination, followed by a parallel-group post-hoc comparative analysis by masked investigators of the videos obtained during the two studies. Parameters analyzed included non-invasive break-up time (NIBUT); dehydration speed (DS) between the initial break and the spontaneous blink, and minimum protected area (MPA) of the lens surface by the tear film.Results: After 3 hours of wear in normal environmental conditions, the overall population (n=148) had a mean NIBUT of 7.1 ± 7.0 sec, a mean DS of 0.28 ± 0.66 mm2/sec, and a mean MPA of 93.4 ± 16.6%. After an additional 3 hours in AEC, mean NIBUT was 8.4 ± 9.8 mm2/sec, mean DS was 0.26 ± 0.75 mm2/sec, and MPA was 95.2 ± 14.0%. The TFK characteristics in the two studies were similar for each environmental condition: after 3 hours of conventional wear, the mean [95% CI] differences between the two studies were −0.9 [−3.2, +1.4] sec for NIBUT, 0.00 [−0.22, +0.22] mm2/s for DS, and 2.0 [−3.5, +7.4] % for MPA; after an additional 3 hours of wear in 20% RH, the mean [95% CI] differences between the two studies were −1.3 [−4.5, +1.9] sec for NIBUT, −0.03 [−0.28, +0.22] mm2/s for DS and −0.3 [−4.9, +4.3] % for MPA. Conclusions: This analysis showed that the measurement of pre-contact lens TFK carried out in two differ-ent studies involving habitual wearers of delefilcon A having worn their contact lenses for an initial 3 hours under NEC and a further 3 hours under low (20%) hygrometry (AEC) produced similar on-eye wettability, including a long NIBUT, slow DS following the initial break, and wide MPA at the next blink. The results establish the reproducibility of the measurement of pre-contact lens TFK using the Tearscope; by quantifying the measurement variability, the data makes it possible to carry out precise sample size calculations in future studies involving pre-contact lens TFK measurements to quantify on-eye wettability under both normal and adverse environmental low (20% RH) hygrometric conditions.

INFLUENCE OF THE SCLERAL LENS AND FLUID RESERVOIR THICKNESSES ON RESIDUAL ASTIGMATISM

PurposeThis study aims to determine if lens or tear fluid reservoir thicknesses (LT/FRT) may influence the presence of residual astigmatism and participant’s visual acuity. MethodsThe study was a randomized, non-dispensing, prospective study. Empirically and randomly chosen participants were fitted with 4 combinations (350 and 250 um LT fitted with 250 and 350 um FRT) of 16 mm diameter scleral lenses, designed using a corneo-scleral profiler software (sMap 3D, Visionary Optics, US). Lenses haptics were kept spherical for all lenses. They were evaluated under a slit lamp, anterior segement OCT (objective fluid reservoir and lens thicknesses), topography over lenses and aberrometry, after 30 minutes of lens wear. Spherico-cylindrical refraction and logMar acuity were also assessed. ResultsStudy population was composed of 24 participants aged 24.2 + 4.7 years old. Baseline refractive error was -2.3 + 1.6 D with -0.48 + 0.26 D of astigmatism. In vivo (OCT) lens A was 344.1 ± 15.4 um thick, fitted with a vault of 213.6 ± 42.4 um; Lens B was 346.2 ± 12.5/327.2 ± 44.8; Lens C was 260.3 ± 17.7/214.0 ± 40.6 um and Lens D was 262.2 ±13.2/330.8 ± 52.0 respectively. All lenses were found similarly decentered inferiorly by 0.10 to 0.15 um. BCVA was −0.32 + 0.08 (A), −0.21 + 0.10 (B), −0.28 + 0.08 (C), and −0.14 + 0.10 (D), compared to −0.25 + 0.08 (A), −0.11 + 0.10 (B), −0.23 + 0.06 (C), and −0.05 + 0.12 (D) when sphere only was compensated. Residual refractive astigmatism (RA = -0.50 to -0.75D) is found significantly higher based on the FRT (F=9.560; p=0.037) and not LT(F=0.429; p=0.522). There is no correlation be-tween RA and over-k readings (Lens A r=-0.078, p=0.773; Lens B r=−0.073, p=0.788; Lens C r=−0.345, p=0.171; Lend D r=0.019, p=0.944). Higher order aberrations, mostly vertical coma, were found clinically significant but not statistically different between lenses (A= 0.350 + 0.032; B=0.382 + 0.053, C=0.329 + 0.044 and D=0.385+ 0.062; p=0.776) ConclusionThis study proves that low level of RA may be found when scleral lenses are fitted on normal corneas. Its occurrence is related to the presence of high-order aberrations and less likely to lens flexure.

Clinical Performance of a Novel Daily Disposable Soft Contact Lens

Background and Objective: Verofilcon A (PRECISION1®; Alcon) silicone hydrogel daily disposable contact lenses were designed to address clinical issues associated with new wearer discontinuation, including vision quality, sustained comfort, and ease of handling. The present study assessed the objective and subjective performance of verofilcon A contact lenses in subjects needing optical correction for refractive ametropia. Material and Methods: Subjects aged 18 years and older with non-diseased eyes, a history of successful soft contact lens wear for distance correction in both eyes during the previous 3 months, and a best spectacle-corrected visual acuity of 20/25 or better with a manifest cylinder of ≤ 0.75 diopters in each eye were recruited. The primary endpoint was distance visual acuity. Secondary endpoints included subjective ratings of overall vision, comfort, and handling, and safety endpoints included adverse events and biomicroscopy/slit lamp examination findings. Results: This study recruited 70 subjects (140 eyes), aged 20–48 years, who were predominantly white (93%), non-Hispanic/Latino (94%), and female (73%); one subject discontinued due to a change in residence. Of the 140 eyes, 132 (94.3%) had 20/20 or better vision with their habitual contact lenses. Similarly, of the 138 eyes that completed the study, 136 (98.6%) had 20/20 or better vision at dispensation of verofilcon A lenses and 132 (95.7%) had 20/20 or better vision at 3 months. Mean ± SD subjective ratings of overall vision, overall comfort, and overall handling, each on a 10-point scale, were 9.4 ± 0.8, 9.4 ± 0.8, and 9.2 ± 1.3, respectively, at lens dispensing, and 9.4 ± 0.9, 9.5 ± 0.8, and 9.2 ± 1.0, respectively, at 3 months. Mean ± SD daily wear times at 1 week and 3 months were 14.71 ± 1.85 and 15.05 ± 1.27 hours, respectively, with 68.1% at 1 week and 73.9% at 3 months wearing verofilcon A lenses for 14–18 hours per day. None of the subjects experienced a serious adverse event or discontinued lens wear, with biomicroscopy/slit lamp examination showing no evidence of corneal edema or chemosis. Conclusion: Subjects wearing verofilcon A lenses had visual acuity similar to that when wearing their habitual lens. Verofilcon A lenses were highly rated for vision quality, comfort, and handling. Verofilcon A lenses may be an option for subjects with refractive ametropia who desire lenses that can be worn for >14 hours per day and are easy to handle.

Ocular Surface Disease in Sjögren's Syndrome: Management in a Scleral Lens Clinical Practice

Sjögren’s syndrome is a chronic, autoimmune, systemic disease characterized by lymphocytic infiltration and malfunction of the exocrine glands, primarily the lacrimal and salivary glands, resulting in predominant symptoms of dry eye and dry mouth. Sjögren’s syndrome is a highly prevalent condition and is one of the most common systemic, rheumatic, autoimmune diseases, affecting up to 1.4% of adults in the United States, second only to rheumatoid arthritis in its prevalence in North America. Primary Sjögren’s syndrome has shown to affect patients’ health-related quality-of-life due to dryness, chronic pain, depression, anxiety,physical and mental fatigue, and neuropsychiatric symptoms. Scleral lenses (SLs) have shown to be significantly beneficial in relieving symptoms and improvingquality-of-life in patients with Sjögren’s syndrome and dry eye disease. SLs may be used concurrently with the other therapies including ocular lubricants, eyelid hygiene, punctal occlusion, topical prescription medications, and autologous serum. This manuscript reviews the implication of Sjögren’s syndrome on the ocular surface and quality-of-life and describes how SLs, in combination with other treatments, may be beneficial.

Performance of Daily Disposable Contact Lenses in Symptomatic Wearers

PurposeTo evaluate the performance of delefilcon A water gradient and narafilcon A silicone hydrogel daily dispos-able contact lenses (CLs) in symptomatic soft CL wearers. MethodsThis multicenter, open-label, crossover study randomized 121 soft CL wearers with symptoms of CL dis-comfort to delefilcon A or narafilcon A for 2 weeks, followed by the alternate lens for 2 weeks. Subjects rated end-of-day (EOD) comfort, EOD dryness, and quality of vision, and investigators rated fit, surface deposits, and surface wettability. ResultsAfter 2 weeks, all subjective measures were better for delefilcon A than for narafilcon A, including EOD comfort (8.3 ± 1.9 vs. 6.6 ± 2.2), EOD dryness (8.0 ± 2.2 vs. 5.8 ± 2.6), and quality of vision (8.9 ± 1.4 vs. 7.9 ± 1.7), all p<.0001. Average daily wear time (DWT; 13.0 ± 2.8 vs. 12.3 ± 2.6 hr) and average comfort-able DWT (11.6 ± 3.9 vs. 9.3 ± 3.8 hr) were longer for delefilcon A lenses (p<.0001). The proportions of right and left lenses without front surface deposits were twofold higher for delefilcon A than for narafilcon A, and surface wettability was significantly higher for delefilcon A than for narafilcon A p<.0001). ConclusionIn this population of symptomatic CL wearers, delefilcon A lenses showed superior subjective ratings for comfort, dryness, quality of vision, DWT, and comfortable DWT and better investigator-rated lens sur-face attributes including fewer surface deposits and superior wettability than did narafilcon A lenses after 2 weeks of wear.

Correlation of Corneal and Scleral Topography in Cases with Ectasias and Normal Corneas

Background and Objective To determine the relationships between corneal and scleral elevation topography in subjects with corneal ectasias and normal corneas. Material and Methods This is a multi-site retrospective study. Ocular surface topography (sMap3D, Precision Ocular Metrology, US) was collected on 115 eyes with prolate cornea profile (Group A) and 227 eyes showing corneal ectasia (Group B). Sagittal height (SAG 1) was measured in the axis of the highest elevated point of the cornea (apex), defined by the meridian joining this apex to the geometrical center of the cornea at an 16 mm chord diameter (8-mm radius). Another sag value was evaluated 180° away (SAG 2) at the same diameter/radius. The difference in height between SAG 1 and SAG 2 represents a quadrant specific effect (QSE). Conjunctival toricity is estimated by comparing the best fit of the conjunctival/scleral shape data to a toric (Sin2) curve; the root- mean-squared error (RMSE) of this curve, a measure of irregularity, was also calculated. Results The ectasia subjects demonstrated greater QSE, (p<0.001), standard toricity (p<0.001) and RMSE (p<0.001) on the sclera compared to normal cornea cases. If the apex of the ectasia was ≥1.25mm from the corneal center, the asymmetry was greater. Within the Group A, standard toricity was significantly higher than QSE (p<0.001) suggesting a more regular conjunctival pattern. As a proof, a significantly greater proportion of cases in Group B vs. Group A (57% vs. 26%, p<0.001) were found with conjunctival irregular shape, as previously defined. In both groups, subjects graded as having spherical/toric scleral shape had significantly lower RMSE values than those graded as having irregular shapes (p<0.001). Conclusion Subjects with corneal ectasia have a different scleral shape compared to those with normal corneal profiles, largely presenting as a quadrant specific effect along the same axis. This difference is higher if the apex of the ectasia is ≥1.25 mm from the corneal center. RMSE seems to correlate with scleral shape classification in both groups.

Influence of Scleral Lens on Intraocular Pressure

Purpose Since Scleral Lenses (SL) rest entirely on the sclera and may affect underlying anatomical structures that may influence aqueous humor flow, it is important to determine the effect of SL wear on intra-ocular pressure (IOP). Methods Nine subjects with normal corneas were recruited for an Institutional Review Board-approved study. Best fit SL from a 15.8 mm diameter 0.4mm thick diagnostic-lens set was fitted on a randomly selected eye, with a silicone-hydrogel soft lens (soft lens) on the other eye. Three IOP measurements were taken with rebound iCare tonometer prior to lens application (baseline data measured at about 9:30AM), and immediately after lens removal (final data measured at about 5:30PM). Baseline and final lens vault was determined with anterior segment Zeiss optical coherence tomography (OCT). Mean baseline and final IOP for each eye was analyzed with a Student-t-test, 2-way repeated ANOVA, and the Bland-Altman plot. RESULTS IOP was elevated with SL wear for all subjects. Soft lens eyes showed a slight elevation for some but decreased in others. Mean IOP change was 5.81 ± 1.62 mm Hg for SL and -0.62 ± 0.88 mm Hg for soft lens eyes. When mean IOP in SL eyes was compared to soft lens eyes, unpaired t-test showed a significant difference (p <0.05) between the means. Bland-Altman bias was 6.43 (SD of bias 3.139). Repeated ANOVA also showed a significant difference between baseline and final IOP. CONCLUSIONS The results indicate that SL wear can elevate IOP. Eye care practitioners (ECP) must consider this possible outcome in treating patients wearing SL. Additional studies are needed to determine the clinical implications of SL wear on IOP.