Corneal surface wettability and tear film stability before and after scleral lens wear

Influence of midday removal and re-application of a scleral lens on fluid reservoir thickness, pre-lens tear film quality and visual acuity

PURPOSE

To investigate whether the midday removal and re-application of scleral lenses (SL) influences fluid reservoir (FR) thickness, pre-lens tear film quality and visual acuity.

METHODS

Two clinical experiments were conducted. A total of 49 keratoconic eyes were evaluated for Part1(tear film and visual acuity analysis) and 12 keratoconic eyes for Part2 (FR thickness analysis). All subjects were wearing 16.4 mm SL for more than 12-months. Tear Film Surface Quality (TFSQ) was evaluated with Medmont E300 at more than 120 min of SL wear, 10 min after SL removal (pre-corneal TFSQ) and 5 min after re-apply the same SL. High and Low Contrast Visual Acuity (HCVA and LCVA) were also assessed with the SL on eye (before and after re-application). For Part2, Anterior OCT (MOptim MOcean4000, China) measurements were taken with and without the SL (at the same time points of Part1) and three outcomes were evaluated: FR thickness, SL thickness (control measurement) and corneal thickness.

RESULTS

Removing and re-applying a SL had a statistically significant positive impact on TFSQ, with an improvement from 0.26 ± 011 to 0.16 ± 0.08 (p = 0.001). This was accompanied by a statistically significant improvement in LogMAR HCVA (from 0.10 ± 0.09 to 0.08 ± 0.08, p < 0.001) and LCVA (from 0.39 ± 0.13 to 0.36 ± 0.13, p < 0.001). Regarding Part2 of the study, a statistically significant increase in FR thickness was observed after SL re-application (from 223.64 ± 48.08 µm to 267.81 ± 80.03 µm, p = 0.007). No changes in corneal thickness were observed.

CONCLUSIONS

Midday removal and re-application of a scleral lens positively impacted pre-lens tear film surface quality, although the observed improvement in visual acuity does not constitute a clinically significant change. Clinicians should consider that removing and reapplying a scleral lens may result in an overestimation of the fluid reservoir thickness, which could affect clinical assessments and treatment decisions.

Visual quality assessment and comparison of two multifocal scleral lens designs

PURPOSE

To analyze the visual quality of a new multifocal scleral lens with a customized decentred optic zone compared to a conventional design by measuring visual acuity, contrast sensitivity function, stereopsis, subjective vision and comfort after one month of wear.

METHODS

Nineteen presbyopic subjects were fitted with two multifocal scleral lens designs: a conventional multifocal and a customized decentred optical zone design. All subjects wore both scleral lens designs for one month with a two-week washout period. The main variables evaluated included high and low-contrast visual acuity under photopic and mesopic light conditions, binocular defocus curves, contrast sensitivity function and a visual analogue scale (VAS) for subjective vision and comfort.

RESULTS

Comparing the two scleral lens designs, statistically significant differences in visual acuity were found, highlighting the improvement in more than one chart line (6 letters) for low contrast near tests under photopic light conditions with the decentred optics lens design. VAS questionnaire scores also showed a significant improvement in distance and overall subjective vision with the decentred optics lenses. Contrast sensitivity function showed an improvement with decentred multifocal lenses at all spatial frequencies measured, being statistically significant for 12 cycles per degree. No differences in stereoacuity were found.

CONCLUSION

Multifocal scleral lenses with a customized decentred optical zone proved to be a promising refractive correction in presbyopic subjects after one month of wear, offering good comfort and visual quality under photopic and mesopic light conditions.

Medmont Meridia™: Much More Than a Corneal Topographer

In recent years, advanced diagnostic instruments have become widely available in optometric practices, offering various functions that optimize clinical information gathering. This article focuses on the Medmont Meridia™, a state-of-the-art multipurpose diagnostic device with corneal topography and cutting-edge features. Corneal topography is pivotal in the early diagnosis of corneal disorders, determining baseline ocular surface assessment, helping in contact lens fitting, and monitoring ocular health over time. The Medmont Meridia boasts Placido-disc-based imaging with extensive corneal coverage. Furthermore, the Meridia accurately measures the horizontal visible iris diameter, pupil diameter, and palpebral fissure width, which assists in making contact lens parameter decisions. Additionally, it offers sagittal height data for scleral lens design and first lens selection, streamlining the fitting process. Beyond its topography capabilities, the Meridia excels as a comprehensive dry eye assessment tool. With features like tear meniscus height, tear film surface quality, and meibography capabilities, it aids in diagnosing dry eye and monitoring its progression. The device also provides customizable dry eye reports with integrated grading scales and questionnaires, making dry eye management, patient education, and compliance more accessible. In conclusion, the Medmont Meridia consolidates a multitude of examination tools in a single instrument, enhancing practice efficiency and elevating patient care and communication. Its versatility and accuracy make it an invaluable asset in optometric practices worldwide.

The influence of large-diameter multifocal contact lens on ocular surface, visual quality, and visual function for presbyopic adults with dry eye syndromes

This study investigated the influence of large-diameter multifocal contact lenses on the ocular surface, visual quality, and visual function for presbyopic adults with dry eye syndromes. The study enrolled 40-55-year-old adults with presbyopia and dry eye syndromes (DES). The subjects were randomly assigned to three groups wearing different designs of contact lenses (Proclear, SMR, and Optimum) for 6-8 h a day for two weeks. Ocular surface health, tear quality, visual quality, and visual function were measured before and after lens wear. No significant difference was observed across all three groups for the amount of conjunctival redness, blink frequency (lens on), and stereopsis vision before and after wearing. Although there seemed to be a significant declining trend for corneal staining and limbal redness, non-invasive tear break-up time (TBUT), and lipid layer thickness while lens wear, the measured values were all within the normal range. Vice-versa after lens removal, results also showed significant improvement on lipid layer thickness, blink frequency (lens off), and contact TBUT. A significant improvement was observed in the modulation transfer function (MTF) of the total area ratio after wearing contact lenses. In contrast, the MTF of the high-order aberration area ratio resulting from lens wear was lower than that of the baseline measurement. There are also significant improvements observed for SMR and Optimum regarding near visual acuity, near point of accommodation, and the subjective questionnaire (OSDI and VBP) scores. Although it is difficult to avoid a specific negative impact on the ocular surface and tear film, visual function and visual quality can still be positively improved, especially shown on larger diameter and distance-center designed multifocal contact lenses.

Anterior, Posterior, and Thickness Cornea Differences after Scleral Lens Wear in Post-LASIK Subjects for One Year

The aim of this study is to analyze the anterior and posterior corneal surface shape and the corneal thickness difference outcomes between before and after scleral lens (ScCL) wear in post-LASIK ectasia subjects for one year. Twenty eyes with post-LASIK ectasia wearing scleral lenses were evaluated in a visit before contact lens and after 1, 6, and 12 months. The study variables analyzed included the apex, nasal, temporal, inferior, and superior corneal thickness; the anterior and posterior surface corneal at corneal diameters of 8, 6, 4, and 2 mm, and high-contrast visual acuity. A statistically significant increment of corneal thickness (p < 0.05) was observed in the inferior area after 6 months and in the superior area in the 12-month follow-up after wearing ScCLs. The anterior corneal curvature presented a flattening and a statistically significant steepening (p < 0.05) in the central and peripheral radii, respectively, after one year. The posterior corneal curvature showed a significant (p < 0.05) steepening, which mainly affected the central region after one year. Despite these changes, high-contrast visual acuity with ScCL correction remained at the same values. The prolonged use of scleral lenses in post-LASIK subjects showed significant changes in the corneal curvature and thickness. These outcomes recommend more detailed and periodic topographic and vision quality checks to monitor the wear in ScCL patients.

Corneal Confocal Analysis after Scleral Lens Wear in Keratoconus Patients: A Pilot Study

SIGNIFICANCE

Scleral lenses rely on the scleroconjunctival region without bearing the cornea, which could improve the symptoms and modify the corneal nerve plexus morphology.

PURPOSE

This study aimed to evaluate symptoms and changes in corneal nerve plexus morphology and density of Langerhans cells in keratoconus patients with and without intrastromal corneal ring before and after scleral lens wear.

METHODS

Sixteen scleral lens wearers with keratoconus were recruited for this short-term experimental pilot study. Subjects were divided into two groups: keratoconus group and intrastromal corneal ring segment group. All subjects were examined in two visits: baseline (before scleral lens wear) and after 6 months of scleral lens wear, after lens removal. The Schirmer I test, the Ocular Surface Disease Index, tear breakup time, and in vivo confocal microscopy were evaluated.

RESULTS

The mean age was 42.33 ± 11.27 years. A significant decrease in tear breakup time was found in the total group ( P = .01, Wilcoxon) compared with baseline. Ocular Surface Disease Index score had decreased after 6 months of scleral lens wear in the keratoconus with intrastromal corneal ring segment subgroup ( P = .03, Wilcoxon) and in the total group ( P = .001, Wilcoxon). No statistical changes in nerve density, tortuosity, and ramification were found for either the total group or the subgroup. However, the mean nerve length was higher in all groups, especially in the keratoconus subgroup ( P = .03, Wilcoxon) after 6 months of scleral lens wear. Regarding optical density, the total group showed a significant increase after 6 months of wearing ( P = .02, Wilcoxon). Finally, Langerhans cell density was not statistically different in any group.

CONCLUSIONS

These results suggest that scleral lens wearing improves the symptoms and increased the mean length nerves after 6 months of wear use in keratoconus patients.

How Can We Best Measure the Performance of Scleral Lenses? Current Insights

Scleral lenses (SLs) present several unique advantageous characteristics for patients. As these lenses are mainly fitted in severely diseased eyes, a thorough evaluation of the ocular surface before and after SL fitting and the on-eye SL fitting evaluation are essential and help minimize potential physiological complications. This review will explore the current and emerging techniques and instrumentation to best measure SL performance ensuring optimal lens fitting, visual quality, comfort and physiological responses, highlighting some potential complications and follow-up recommendations. A single physician could perform the great majority of evaluations. Still, the authors consider that the assessment of SL fitting should be a collaborative and multidisciplinary job, involving contact lens practitioners, ophthalmologists and the industry. This publication has reviewed the most up-to-date work and listed the most used techniques; however, the authors encourage the development of more evidence-based recommendations for SL clinical practice.

Dry Eye Symptoms in Individuals With Keratoconus Wearing Contact Lenses

OBJECTIVES

To assess dry eye symptoms associated with different contact lens modalities in patients with keratoconus using a dry eye questionnaire.

METHODS

An online survey was distributed by the National Keratoconus Foundation. The survey asked participants to report demographic characteristics, current optical correction, age at the time of diagnosis of keratoconus, and contact lens history. The 12-item Ocular Surface Disease Index (OSDI) questionnaire was also completed. Data from participants wearing the same contact lens modality bilaterally were analyzed.

RESULTS

The survey was completed by 197 individuals wearing the same contact lens modality bilaterally. The average age of participants at the time of the survey was 47.2±14.8 years (range: 15-87 years), and the average age at which keratoconus was diagnosed was 26.1±9.9 years (range: 8-55 years). The mean overall OSDI score of all participants was 40.2±22.8 (range: 0-100). There was no difference in the mean OSDI scores based on current contact lens modality type (F=1.79; n=187; P=0.13). Based on an OSDI score of 33 or higher, 90% of participants reported symptoms indicative of dry eye disease. Scleral lens wearers reported less discomfort on the individual items related to windy and low-humidity conditions.

CONCLUSIONS

Individuals with keratoconus, irrespective of contact lens modality, report a high incidence of dry eye symptoms.

Assessment of a Novel Lens Surface Treatment for Scleral Lens Wearers With Dry Eye

OBJECTIVES

To compare lens comfort and dry eye (DE) symptoms of DE scleral lens (SL) wearers fit with polyethylene glycol (PEG)-based surface-treated and untreated SLs. Dry eye signs, comfortable SL wearing time (WT), vision quality, and lens-related ocular surface changes were also assessed.

METHODS

Twenty-one SL wearers with DE and SL discomfort were enrolled in a double-masked crossover study. Participants were randomized to wear their untreated or PEG (Tangible Hydra-PEG, Tangible Science; Redwood, CA) surface-treated SL of the same parameters first for 30 days. Lens comfort, DE symptoms, and ocular surface assessments were measured at baseline, after the first test period, and after the crossover. Comfortable lens WT and frequency of foggy vision were recorded. Comparisons were assessed using paired t tests or Wilcoxon signed-rank tests.

RESULTS

Polyethylene glycol-treated SL wear resulted in significantly improved: lens comfort (P=0.003), DE symptoms (P=0.004), corneal sodium fluorescein staining (P=0.01), temporal conjunctival lissamine green staining (P=0.01), lid wiper epitheliopathy (P=0.002), conjunctival papillae (P=0.003), frequency of foggy vision (P=0.002), tear break-up time (TBUT) (P=0.01), and comfortable lens WT (P=0.002) compared with untreated wear. There were no significant changes between treated and untreated lens wear for TBUT over the SL (P=0.14) and nasal conjunctival lissamine green staining (P=0.06).

CONCLUSIONS

Polyethylene glycol surface-treated SLs provided improved comfort, reduced DE symptoms, and reduced ocular surface compromise compared with untreated SLs for participants with DE.

CLEAR - Scleral lenses

Scleral lenses were the first type of contact lens, developed in the late nineteenth century to restore vision and protect the ocular surface. With the advent of rigid corneal lenses in the middle of the twentieth century and soft lenses in the 1970's, the use of scleral lenses diminished; in recent times there has been a resurgence in their use driven by advances in manufacturing and ocular imaging technology. Scleral lenses are often the only viable form of contact lens wear across a range of clinical indications and can potentially delay the need for corneal surgery. This report provides a brief historical review of scleral lenses and a detailed account of contemporary scleral lens practice including common indications and recommended terminology. Recent research on ocular surface shape is presented, in addition to a comprehensive account of modern scleral lens fitting and on-eye evaluation. A range of optical and physiological challenges associated with scleral lenses are presented, including options for the clinical management of a range of ocular conditions. Future applications which take advantage of the stability of scleral lenses are also discussed. In summary, this report presents evidence-based recommendations to optimise patient outcomes in modern scleral lens practice.

Anatomical and physiological considerations in scleral lens wear: Eyelids and tear film

Scleral lenses can affect a range of anterior segment structures including the eyelids and the tears. The eyelids, consisting of the outer skin layer, the middle tarsal plate, and the posterior palpebral conjunctiva, provide physical protection and house the meibomian glands and cilia which have important and unique functions. Tears consist of a mix of aqueous, mucus, and lipidomic components that serve vital functions of lubricity, protection, and nourishment to the ocular surface. Both the eyelids and the tear film interact directly with scleral lenses on the eye and can affect but also be impacted by scleral lens wear. The purpose of this paper is to review the anatomy and physiology of the eyelids and tear film, discuss the effects and impacts of the scleral lenses on these structures, and identify areas that require further research.