Assessment of a practitioner's perception of scleral contact lens complications.

PURPOSE: The purpose of this survey was to better understand scleral lens (SL) practitioners' fitting preferences and minor SL complications and their subsequent treatments. METHOD: Practitioners who attended the 2017 Global Specialty Lens Symposium were asked to complete an electronic questionnaire that was created by the investigators, a survey that asked practitioners about their SL fitting experience and preferences, their patients' experience with poor SL wetting, SL fogging, ocular symptoms (redness, pain/discomfort, dryness), and blurred central and side vision, and how the practitioners treated these conditions. RESULTS: This study analyzed data from 164 SL practitioners. The practitioners had been in practice for 16.3 ± 13.4 years, had been fitting SL for 5.5 ± 5.0 years, and fit 7.4 ± 7.1 SL/month. Practitioners preferred a SL with a final central corneal clearance of ∼200 µm and an overall diameter between 15.1 mm to 16.5 mm. Poor SL wetting (90.8% of practitioners documented condition), SL fogging (84.8%), blurred central vision (40.2%), ocular redness (34.8%), ocular dryness (24.4%), ocular pain/discomfort (20.7%), and blurred side vision (12.8%) were encountered by the practitioners. Practitioners preferred treating poor wetting and fogging with lens removal, cleaning, and reapplication, blurred central vision with a lens power change, blurred side (peripheral) vision, ocular redness, and ocular pain with a lens parameter change, and dryness with artificial tears. CONCLUSIONS: Most SL practitioners preferred a SL central corneal clearance of ∼200 µm, and they occasionally encountered SL-related complications in their practice, which they treated similarly to corneal gas permeable CLs.

A Randomized Trial to Evaluate the Effect of Toric Versus Spherical Contact Lenses on Vision and Eyestrain.

OBJECTIVES: To compare the effect of toric versus spherical soft contact lenses on objective measures of visual performance using visual acuity and electromyography of the orbicularis oculi muscle. METHODS: Current soft contact lens wearers with -0.75 to -1.75 D astigmatism in each eye were binocularly fitted with toric (1-Day ACUVUE MOIST for astigmatism) and spherical (1-Day ACUVUE MOIST) contact lenses in random order. After each fitting and at 1-week follow-up, high- and low-contrast visual acuities were measured. Electromyography was used to objectively evaluate eyestrain. Linear mixed models were used to assess differences between toric and spherical contact lenses. RESULTS: The mean age (±SD) of the 60 participants was 27.5±5.0 years, spherical refractive error was -3.68±2.01 D, and cylinder was -1.28±0.36 D. High- and low-contrast visual acuities with toric lenses were better than with spherical lenses at both fitting (toric high-contrast: -0.065±0.078 and low-contrast: 0.133±0.103 vs. spherical high-contrast: 0.001±0.104 and low-contrast: 0.224±0.107) and follow-up (toric high-contrast: -0.083±0.087 and low-contrast: 0.108±0.107 vs. spherical high-contrast: -0.015±0.095 and low-contrast: 0.211±0.104) (all P<0.0001). Electromyography-measured eyestrain was less with toric versus spherical contact lenses at fitting (least-square ratio of toric over spherical=0.72; P=0.0019) but not at follow-up (ratio=0.86; P=0.11). CONCLUSION: These results suggest that toric contact lenses provided improved objective measures of vision in a low-to-moderate astigmatic population.

Efficacy of Toric Contact Lenses in Fitting and Patient-Reported Outcomes in Contact Lens Wearers.

OBJECTIVES: To assess whether patient-reported measures are improved with soft toric contact lenses (TCLs) compared with soft spherical contact lenses (SCLs) and whether clinical time needed to fit TCL is greater than SCL. METHODS: Habitual contact lens wearers with vertexed spherical refraction +4.00 to +0.25 D or -0.50 to -9.00 D and cylinder -0.75 to -1.75 DC were randomly assigned to be binocularly fitted into a TCL or SCL, and masked to treatment assignment. Time to successful fit was recorded. After 5 days, the National Eye Institute Refractive Error Quality of Life Instrument (NEI-RQL-42) and modified Convergence Insufficiency Symptom Survey (CISS) were completed. After washout, subjects were fit into the alternative lens design (TCL or SCL). Outcomes were evaluated using linear mixed models for the time to fit and CISS score, generalized linear model for the successful fit, and Wilcoxon tests for the NEI-RQL-42. RESULTS: Sixty subjects (71.7% women, mean age [±SD] = 27.5±5.0 years) completed the study. The mean time to fit the TCL was 10.2±4.3 and 9.0±6.5 min for the SCL (least square [LS] mean difference (TCL-SCL)=1.2, P=0.22). Toric contact lens scored better than SCL in global NEI-RQL-42 score (P=0.006) and the clarity of vision (P=0.006) and satisfaction with correction subscales (P=0.006). CISS showed a 15% reduction in symptoms (LS mean difference [TCL-SCL]=-2.20, P=0.02). CONCLUSION: TCLs are a good option when trying to improve the vision of patients with low-to-moderate astigmatism given the subjective improvements in outcomes.

Subjective Comfort and Physiology with Modern Contact Lens Care Products.

PURPOSE: To compare subjective comfort and ocular physiology with three multipurpose solutions (MPSs) to that of a peroxide-based system with three different soft contact lens materials. METHODS: Habitual soft contact lens wearers (n = 236) were enrolled at three sites and completed a washout period with no contact lens solution for ≥4 days. Subjects were randomly assigned to one of three lens types: etafilcon A, galyfilcon A, or senofilcon A. A new lens of the assigned type was worn for 10 to 14 days each while using one of four care solutions, in random order (A-polyaminopropyl biguanide + polyquaternium, B-POLYQUAD + Aldox, C-alexidine + polyquaternium-1, and D-hydrogen peroxide) with a washout period (≥4 days) between each solution. After each care solution, biomicroscopy was performed and subjective comfort was assessed using the Contact Lens User Experience (CLUE) questionnaire and other instruments including comfortable wear time (CWT). Linear mixed models were used for analysis. Comfort and biomicroscopy signs with each MPS were compared to that of the peroxide solution. RESULTS: Subjective CLUE Comfort score across all lens types with each MPS was not significantly different than with the peroxide solution (p = 0.98). There were no differences in CWT between each MPS and the peroxide solution for any lens type (range of differences: -0.8 to 0.8 h; all p ≥ 0.13). Six MPS/material combinations had no clinically meaningful change in corneal staining versus peroxide (<0.5 units); three combinations could increase staining by up to 0.57 units. Staining was

Lamellar changes in the keratoconic cornea.

PURPOSE: The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning. METHODS: Five surgically removed keratoconic corneal buttons and four, non-keratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled. A seamless digital montage was printed at 5000× magnification. Lamellae were counted in the anterior-posterior orientation, along a linear line, using established criteria for identification of individual lamellae. RESULTS: The stromal thickness estimated as a 95% confidence interval for the mean, CI (0.95), in the keratoconic corneas was 372 ± 62 µm, while in the normal cornea, it was 446 ± 89 µm. All keratoconic corneas showed ultrastructural evidence of lamellar splitting and a loss of interweaving anterior lamellae. In the keratoconic corneas, the median total linear stromal lamellar absolute count tangential to the corneal surface was 362, (25th percentile; 75th percentile) = (355; 365) lamellae and in the normal cornea, 246, (25th percentile; 75th percentile) = (239; 251). The linear lamellar density in the keratoconic corneas was estimated as CI (0.95) 117 ± 22 and 86 ±19 lamellae per 100 µm in the anterior and posterior portion of the stroma, respectively. In normal cornea, the linear lamellar density was estimated as CI (0.95) 51 ± 8 and 80 ± 20 lamellae per 100 µm. The mean difference of linear lamellar count between the anterior and the posterior portion of the cornea was estimated as CI (0.95) 31 ± 23 for keratoconic corneas and -29 ± 28 for the normal corneas. CONCLUSIONS: The current morphometric analysis of ultrastructural changes suggests that ectasia and thinning in keratoconus is associated with lamellar splitting into multiple bundles of collagen fibrils and loss of anterior lamellae. These structural changes, possibly in addition to lateral shifting of lamellae due to the pressure gradient over the cornea, are a potential explanation to the central loss of mass.

Recurrence or re-emergence of keratoconus--what is the evidence telling us? Literature review and two case reports.

Keratoconus may recur following penetrating or lamellar keratoplasty, but latency is considerably longer in the former. Since keratoplasty involves only partial excision of the cornea, and recent research strongly indicates the presence of the pathology in the peripheral host cornea, the reappearance of the pathology after a latency period is most likely due to migration of the disease from host to donor cornea. This notion is further corroborated by the shorter latency period in partial thickness keratoplasty, where more of the diseased host cornea remains in place. Other proposed causes for the recurrence of keratoconus, such as eye rubbing and contact lens wear, were reportedly not associated with a significant number of cases, and, therefore, are not the primary factor. Based on existing literature, it is concluded that, in post-keratoplasty keratoconus, the etiology stems from re-emergence of the disease rather than recurrence. Keratoconus patients in need of keratoplasty should be counseled on the possibility of the disease re-emerging.

Quantified histopathology of the keratoconic cornea.

PURPOSE: This study systematically investigated and quantified histopathological changes in a series of keratoconic (Kc) corneas using a physiologically formulated fixative to not further distort the already distorted diseased corneas. METHODS: Twelve surgically removed Kc corneal buttons were immediately preserved and processed for light and transmission electron microscopy using an established corneal protocol. Measurements were taken from the central cone and peripheral regions of the host button. The sample size examined ranged in length from 390 to 2608 µm centrally and 439 to 2242 µm peripherally. RESULTS: The average corneal thickness was 437 µm centrally and 559 µm peripherally. Epithelial thickness varied centrally from 14 to 92 µm and peripherally from 30 to 91 µm. A marked thickening of the epithelial basement membrane was noted in 58% of corneas. Centrally, anterior limiting lamina (ALL) was thinned or lost over 60% of the area examined, whereas peripheral cornea was also affected but to a lesser extent. Histopathologically, posterior cornea remained undisturbed by the disease. Anteriorly in the stroma, an increased number of cells and tissue debris were encountered, and some of these cells were clearly not keratocytes. CONCLUSIONS: It is concluded that Kc pathology, at least initially, has a distinct anterior focus involving the epithelium, ALL, and anterior stroma. The epithelium had lost its cellular uniformity and was compromised by the loss or damage to the ALL. The activity of the hitherto unreported recruited stromal cells may be to break down and remove ALL and anterior stromal lamellae, leading to the overall thinning that accompanies this disease.

Fine structure of the interface between the anterior limiting lamina and the anterior stromal fibrils of the human cornea.

PURPOSE: To use transmission electron microscopy (TEM) to investigate further the ultrastructural details of the collagen fibrils linking the anterior limiting lamina (ALL; Bowman's membrane) of the human cornea to the anterior stromal lamellae. METHODS: Six disease-free corneas from donors aged 42 to 82 years were fixed (2% glutaraldehyde in 80 mM sodium cacodylate) and processed for TEM within 72 hours postmortem. A series of overlapping images, at 10,204x magnification, of the central corneal ALL-stroma interface were assembled. The features of the terminal ends of fibril bundles at the interface with the anterior stroma were quantitatively assessed. RESULTS: TEM revealed apparently terminating anterior stromal fibril bundles adjacent to the ALL. These terminating lamellae (7.8 per 100 mum) were embedded in an electron-dense material within the surrounding stromal matrix and were termed electron-dense formations (EDFs). The mean width of these stromal features was 1.6 mum. At intervals, anterior stromal lamellae approached the ALL and, in a shallow manner, inserted into the ALL. Such projections (5.4 per 100 mum) into the ALL were, on average, less than 1 mum. Numerous fibrils (29.8 per 100 mum) extended from the ALL into the stroma with a mean length of 0.8 mum. CONCLUSIONS: The interface the ALL forms with the anterior stroma is complex, and TEM revealed at least three different types of fibrillar arrangements, which may serve optical requirements rather than provide a structural function.