Scleral Lenses for Managing Dry Eye Disease

Scleral Lenses for Managing Dry Eye Disease in the Absence of Corneal Irregularities

Abstract

• Scleral lenses (SLs) are typically used for correcting corneal irregularities but are gaining traction for managing dry eye disease (DED) due to their unique ability to create a fluid reservoir over the cornea.

• SLs have demonstrated symptomatic relief for DED patients, even in the absence of corneal irregularities or other ocular surface diseases (OSDs), by maintaining a constant moist environment and protecting the ocular surface.

• The TFOS DEWS II Report treatment hierarchy for DED currently places SLs at Step 3, but there is ongoing discussion and increasing support for moving SLs to an earlier stage in the treatment paradigm due to their potential benefits.

• This article reviews the existing evidence supporting the use of SLs in DED management, highlighting benefits such as promoting corneal healing, preventing tear evaporation and contact lens dehydration, improving visual acuity, and enhancing overall comfort.

• Several challenges may arise when fitting SLs in DED patients, including managing midday fogging, ensuring proper lens wettability, and addressing specific patient satisfaction issues related to comfort and handling.

• Overall, while further research is essential to fully elucidate the role of SLs in DED management, their ancillary benefits suggest a broader application in managing DED, particularly for patients who have not responded adequately to conventional treatments.

• Keywords: scleral lenses, dry eye disease, clinical decision-making, contact lenses

1. Introduction

• Scleral lenses (SLs) are large-diameter rigid contact lenses designed to vault over the entire cornea, landing on the conjunctiva that overlays the sclera $[1]$. This unique design allows for the creation of a fluid-filled space between the lens and the cornea, which is particularly beneficial for managing various ocular surface conditions.

• Traditionally, SLs have been primarily utilized for the visual rehabilitation of patients with irregular corneas $[2–4]$, addressing conditions such as:

  • Primary and secondary ectatic diseases: Keratoconus, pellucid marginal degeneration, and post-LASIK ectasia.

  • Corneal scarring: Resulting from infections, injuries, or previous surgeries.

  • Post-refractive surgery: Including cases with irregular astigmatism or corneal ectasia following procedures like LASIK or PRK.

  • Post-penetrating keratoplasty: To correct high astigmatism and irregular corneal surfaces after corneal transplantation.

• However, SLs are now increasingly recognized and used for cases with regular corneas $[2–4]$, expanding their application to include:

  • Dry eye disease (DED) management: Providing a protective barrier and consistent hydration for severe DED cases.

  • High refractive error correction: Offering stable and high-quality vision correction for patients with myopia, hyperopia, and astigmatism.

• Dry eye disease (DED) is defined by the TFOS DEWS II as a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film. This condition is accompanied by ocular symptoms and involves several etiological factors $[5]$:

  • Tear film instability and hyperosmolarity: Leading to rapid tear breakup and increased salt concentration on the ocular surface.

  • Ocular surface inflammation and damage: Triggering epithelial cell apoptosis and corneal surface irregularities.

  • Neurosensory abnormalities: Affecting corneal sensitivity and tear production.

• Scleral lenses are applied with non-preserved saline solution to fill the space between the lens and the cornea, creating a continuously moist environment that prevents fluid evaporation and protects the sensitive corneal surface $[6]$.

• Currently, in the TFOS DEWS II Report treatment hierarchy for DED, SLs are positioned at Step 3, typically considered after other interventions have been tried without sufficient success $[7]$. These prior interventions may include:

  • Overnight moisture chamber devices: To reduce tear evaporation during sleep.

  • Intense pulsed light (IPL) therapy: To improve meibomian gland function in evaporative dry eye.

  • Topical and oral prescription medications: Such as cyclosporine, lifitegrast, or systemic omega-3 fatty acids to reduce inflammation and improve tear quality.

• Due to successful clinical outcomes, many clinicians have reported effective DED management with SLs, which has led to discussions and considerations for using them earlier in the treatment process $[8]$, potentially improving patient outcomes and quality of life.

• This article aims to comprehensively review the existing evidence regarding the efficacy of SLs in managing DED. It will also discuss the potential advantages and challenges associated with fitting SLs in patients with DED, providing a balanced perspective on their role in clinical practice.

2. Current Evidence Supporting the Use of SLs in DED and OSD Patients

2.1. SLs for DED Management with Associated Corneal Irregularities and Other Forms of OSD

• Ocular surface disease (OSD) is a broad term encompassing various conditions that affect the ocular surface, including the cornea, conjunctiva, and tear film $[9]$, with DED being a significant subset.

• Various OSDs, such as exposure keratopathy and graft-versus-host disease (GVHD), can lead to or exacerbate DED symptoms $[5,9]$. Exposure keratopathy results from inadequate eyelid closure, while GVHD is a common complication following hematopoietic stem cell transplantation.

• SLs are frequently prescribed for OSDs to provide ocular surface protection, facilitate corneal healing, and alleviate symptoms $[10,11]$. Additionally, they can restore and rehabilitate vision in cases where corneal irregularity is present $[12,13]$.

• The efficacy of SLs in managing OSDs with associated corneal irregularities has been extensively reviewed $[10,11]$ for conditions such as GVHD, Stevens–Johnson syndrome (SJS), Sjögren’s syndrome, exposure keratopathy, and post-refractive surgery dry eye. These reviews highlight the role of SLs in protecting the cornea and improving patient comfort.

• While most reports indicate that SLs are indeed effective in managing OSD, it is important to note that many studies have limitations such as small sample sizes (level 2 evidence) or are presented as individual case reports (level 3 evidence) $[12]$. This underscores the need for larger, more robust studies to strengthen the evidence base.

• Some studies include heterogeneous populations with various OSDs, and only a subset of these patients may have pure DED $[14–16]$. This mixed population makes it challenging to isolate the specific benefits of SLs for DED alone.

• Studies that specifically focus on fitting DED patients with SLs have shown significant improvements in Ocular Surface Disease Index (OSDI) scores $[14–16]$. The OSDI is a widely used questionnaire to assess the severity of dry eye symptoms and their impact on daily activities.

• Researchers have also reported a significant decrease in tear osmolarity $[14]$ and improvements in corneal and conjunctival staining $[15]$, suggesting the potential utility of SLs in improving the overall ocular surface health of DED patients. Tear osmolarity is a key marker of tear film instability, and reduced staining indicates improved epithelial integrity.

• In ocular GVHD, dry eye is a prevalent and debilitating symptom $[17]$. Studies have demonstrated that SLs provide significant symptomatic relief from ocular dryness, irritation, and foreign body sensation in these patients $[6,18–22]$. Additionally, one study reported a significant improvement in OSDI scores following SL fitting $[20]$, further supporting the use of SLs in managing GVHD-related dry eye.

• DED is estimated to affect approximately one-third of patients with SJS in the chronic stage $[23]$. A retrospective chart review indicated that SL wear led to significant improvements in OSDI scores in SJS and toxic epidermal necrolysis (TEN) patients $[24]$. Furthermore, a case report documented symptomatic relief of DED symptoms in an SJS patient with SL wear $[25]$, highlighting the potential benefits of SLs in this patient population.

• In exposure keratopathy, a retrospective chart review revealed that SL wear significantly improved OSDI scores and reduced corneal staining $[26]$. This improvement is likely due to the protective effect of SLs, which shield the cornea from exposure and promote healing.

• The prevalence of post-refractive surgery dry eye has been reported to range from 36% to 75% $[27]$. Marty et al. found significant improvements in OSDI scores with SL wear in patients with post-refractive surgery ectasia $[28]$, indicating that SLs can effectively manage dry eye symptoms in this context.

2.2. SLs for DED Management without Associated Corneal Irregularities and Other Forms of OSD

• A comprehensive literature review was conducted on PubMed on February 15, 2024, using the search terms "scleral lenses" and "dry eye disease," which yielded 83 papers.

• After excluding studies that included non-DED OSD cases with corneal irregularities, only two published abstracts remained, underscoring the limited evidence available specifically for managing DED without corneal irregularities.

• One abstract, presented at the 2024 Global Specialty Lens Symposium, reported on a prospective, randomized, double-masked study involving 20 symptomatic soft-lens wearers without corneal irregularities $[29]$.

  • In this study, subjects completed a dry eye questionnaire (CLDEQ-8) and rated their contact lens comfort and dryness levels while wearing their habitual soft contact lenses and after switching to SLs for one month $[29]$.

  • The results showed a significant improvement in CLDEQ-8 scores and subjective ratings of comfort and dryness with SLs compared to soft lenses $[29]$, indicating that SLs may offer enhanced comfort and reduced dryness symptoms.

  • Notably, 45% of the subjects expressed a desire to continue wearing SLs after the study $[29]$, highlighting their satisfaction with the lenses.

  • The authors concluded that switching to SLs improved overall comfort and reduced dryness symptoms in symptomatic soft contact lens wearers $[29]$, suggesting that SLs could be a viable alternative for those experiencing contact lens-related dry eye.

• The second abstract, presented at the 2024 Netherlands Contact Lens Congress, included 18 symptomatic non-contact lens wearers who did not have corneal irregularities $[30]$.

  • Compared to baseline, the study found a significant improvement in CLDEQ-8 scores and subjective comfort/dryness ratings with SL wear $[30]$, suggesting that SLs can alleviate dry eye symptoms even in individuals who do not typically wear contact lenses.

  • Similar to the previous study, 44% of subjects wanted to continue wearing SLs after the study concluded $[30]$, indicating a relatively high level of satisfaction.

  • The authors concluded that SLs improved comfort and reduced dryness symptoms and should be considered as a management option for this specific patient population $[30]$.

• These two abstracts represent the only level 2 evidence currently available on managing symptomatic DED without corneal irregularities and other forms of OSD with SLs. This highlights the need for further well-designed studies to strengthen the evidence base in this area.

• Currently, there is insufficient high-quality evidence to definitively recommend the widespread use of SLs in mild to moderate DED cases. More robust clinical trials are needed to establish clear guidelines and recommendations.

• Table 1 summarizes studies on the efficacy of SLs in the management of DED, both with and without associated corneal irregularities and other forms of OSD. This table provides a concise overview of the available evidence and study characteristics.

3. Advantages of Fitting SLs in DED

• Despite the limited evidence base, SLs are believed to offer several potential advantages for managing symptomatic DED without corneal irregularities and other forms of OSD. These benefits are particularly relevant for symptomatic soft contact lens wearers who experience discomfort and dryness.

• These advantages include providing ocular surface protection, promoting corneal healing, eliminating contact lens dehydration and tear film evaporation, and improving visual acuity and associated wear comfort. These factors can collectively contribute to enhanced patient satisfaction and improved quality of life.

3.1. Elimination of Tear Film Evaporation

• With SL wear, the ocular surface is consistently enclosed in a moist environment, effectively preventing direct fluid evaporation. This is a key feature in managing dry eye symptoms.

• The natural tear film comprises a lipid layer and a mucoaqueous layer, containing various components such as lipids, electrolytes, mucins, proteins, and metabolites $[31,32]$. These components work together to maintain tear film stability and prevent evaporation.

• The outer lipid layer is crucial in preventing the evaporation of the aqueous layer. However, this lipid layer can thin with soft contact lens wear $[33,34]$, potentially leading to increased tear evaporation and discomfort.

• The post-lens tear film in a SL consists of non-preserved saline and components of the natural tear film, resulting in a completely different structure characterized by minimal tear exchange and evaporation $[32]$. This stable fluid reservoir helps maintain a hydrated ocular surface.

• Future studies involving detailed tear film analysis with SLs may provide valuable insights into how SLs prevent or improve DED symptoms. Understanding the specific changes in tear film composition and function can help optimize SL designs and fitting strategies.

• DED is classified into two main subtypes: aqueous deficient dry eye (ADDE) and evaporative dry eye (EDE) $[5]$, which exist on a continuum with a preponderance of EDE $[5]$. ADDE is characterized by reduced tear production, while EDE is caused by increased tear evaporation.

• Some studies have demonstrated increased tear evaporation with soft contact lens wear $[35–38]$ and a concurrent increase in DED symptoms $[37]$, suggesting that increased tear evaporation plays a significant role in contact lens-induced DED. This highlights the importance of addressing tear evaporation in managing DED.

• SL wear ensures adequate hydration and eliminates tear evaporation over the ocular surface, potentially benefiting both ADDE and EDE patients. By maintaining a constant moist environment, SLs can alleviate symptoms and improve overall ocular surface health.

3.2. Elimination of Contact Lens Dehydration

• Scleral lenses are made of rigid gas-permeable (GP) materials that do not contain water; thus, there is no contact lens dehydration associated with their wear. This is a significant advantage over soft contact lenses, which are prone to dehydration.

• Soft contact lenses are susceptible to dehydration, depending on factors such as material composition, environmental humidity, air flow, and temperature $[39,40]$. These factors can influence the water content of the lens and impact patient comfort.

• Soft contact lens dehydration may be associated with discomfort and dryness, although a direct causative link has not been definitively established $[39,41–44]$. However, maintaining lens hydration is generally considered important for overall wear comfort.

• SLs are made of rigid gas-permeable (GP) material with no water content, eliminating dehydration as a potential factor contributing to symptoms. This stability can lead to more consistent and comfortable wear throughout the day.

• Corneal GPs are generally not considered a suitable option for DED management because they make direct contact with the corneal epithelium during blinking $[45]$, potentially causing foreign body sensation and discomfort $[45]$. This direct contact can irritate the ocular surface and exacerbate dry eye symptoms.

• Corneal GPs do not provide a stable post-lens tear film and may disrupt the tear film composition by thinning the lipid layer, potentially leading to increased tear evaporation $[45,46]$. This disruption can worsen tear film instability and increase the severity of dry eye symptoms.

3.3. Corneal Healing

• SLs have the potential to promote corneal healing and improve overall corneal health. This is particularly beneficial for patients with corneal damage or epithelial defects.

• Studies have shown that SL wear reduces corneal staining, as evidenced by case reports and case series in OSD management $[47,48]$. Reduced staining indicates improved epithelial integrity and a healthier corneal surface.

• A global survey reported that the incidence of corneal staining reduced from 55% pre-SL wear to 35% post-SL wear $[49]$. This significant reduction underscores the positive impact of SLs on corneal health.

• The corneal healing effect of SLs is well documented in the management of neurotrophic keratitis, where SL wear can help heal persistent epithelial defects $[50–53]$. Neurotrophic keratitis is a condition characterized by impaired corneal sensation and poor healing, and SLs provide a protective environment that promotes corneal recovery.

• The precise physiological pathway through which SL wear promotes corneal healing remains unclear and requires further investigation. Understanding the underlying mechanisms can help optimize SL designs and treatment protocols.

• Reduced corneal staining has been observed clinically after SL wear in DED cases, and it is hypothesized that this effect could be more broadly applicable if these lenses were used more widely. This suggests that SLs have the potential to improve corneal health in a broader range of DED patients.

3.4. Improved Visual Acuity

• SLs can potentially improve visual acuity and enhance the comfort of contact lens wear. This is particularly relevant for patients who experience visual disturbances due to dry eye or corneal irregularities.

• Research on soft contact lenses indicates that reduced visual acuity is associated with worse perceived contact lens wear comfort $[54,55]$. This suggests that improving visual acuity can positively impact overall wear comfort.

• Studies have found that SLs provide improved best-corrected visual acuity compared to habitual visual correction in eyes with regular corneas $[49,56]$. This improvement is likely due to the ability of SLs to mask corneal irregularities and provide a smoother refracting surface.

• The post-lens tear film behind a SL can mask anterior corneal astigmatism and other irregularities $[57]$, creating a smoother refracting surface that may lead to better visual acuity. This improved optical quality can enhance visual performance and reduce visual fatigue.

• The improvement in best-corrected visual acuity with SL wear may contribute to better wear comfort. Clearer vision can reduce eye strain and improve overall satisfaction with contact lens wear.

• Currently, no studies have specifically investigated this subject with SLs. Further research is needed to confirm this relationship and quantify the impact of improved visual acuity on wear comfort with SLs.

• Based on research with soft contact lenses, inferences can be made on the potential advantages of wearing SLs for DED patients without associated corneal irregularities or other forms of OSD. However, more SL-specific research is needed to support prescribing SLs in this patient population. Understanding the unique benefits and challenges of SLs in DED management can help guide clinical decision-making.

• As the above-proposed advantages of SL wear directly address issues of contact lens discomfort related to soft contact lens wear, future studies should aim to include symptomatic soft contact lens wearers and non-contact lens wearers when investigating the efficacy of SLs when managing DED, as shown by the two published abstracts $[29,30]$. This approach will provide valuable insights into the potential of SLs to improve comfort and reduce dryness symptoms in a broader range of patients.

4. Challenges of Fitting SLs in DED

• Despite the potential benefits, several challenges must be carefully considered when fitting SLs in DED patients with regular corneas. These challenges include managing midday fogging (MDF), ensuring proper lens wettability, and addressing patient expectations.

4.1. MDF

• Midday fogging (MDF) is a common complication estimated to affect between 26% to 46% of SL wearers $[58–60]$. MDF can significantly impact visual clarity and overall satisfaction with SL wear.

• In MDF, debris becomes trapped and accumulates in the post-lens tear film created by a SL. This debris can include proteins, lipids, and inflammatory cells, which can cloud the vision.

• With a significant accumulation of debris, visual acuity can be substantially impacted $[58]$, leading to blurred vision and reduced clarity. Patients often report needing to remove and clean their lenses multiple times during the day to alleviate MDF.

• Patients with DED have a higher incidence of MDF, with 50 out of 69 patients who wore SLs for DED reporting MDF $[61]$, a 75% rate, which is higher than the average of 26% to 46% reported in other SL studies $[58–60]$. This increased incidence highlights the challenges of managing MDF in DED patients.

• Another study reported a relationship between the OSDI score of SL wearers and MDF, with participants reporting MDF having a more severe OSDI compared to those who were MDF-free $[62]$. This suggests that the severity of dry eye symptoms may be associated with an increased risk of MDF.

• The higher incidence of MDF in DED patients could be attributed to inflammation, which is a potential common denominator for both DED and MDF. Inflammation can increase the production of debris and inflammatory mediators in the tear film.

• The TFOS DEWS II definition includes “ocular surface inflammation” as one of the underlying etiologies of DED $[5]$. Chronic inflammation can disrupt tear film homeostasis and contribute to the development of dry eye symptoms.

• Increased levels of inflammatory markers have been linked to an increased incidence of MDF $[32,63]$. These markers can promote the accumulation of debris and exacerbate MDF symptoms.

• Leukocytes, particularly neutrophils, have been found in the post-lens tear film of SL patients, especially those who reported MDF $[59]$. These inflammatory cells can contribute to the formation of debris and clouding of the vision.

• Levels of inflammatory mediators, such as matrix metalloproteinase (MMP)-9 and -10, are also significantly elevated in the post-lens tear film after 8 h of SL wear when compared to the levels in basal tears $[64]$. These enzymes can degrade tear film components and promote inflammation.

• To date, no tear film analysis study has been performed specifically on DED patients who report MDF. Such studies could provide valuable insights into the underlying mechanisms and potential treatment strategies for MDF in this population.

• Patients who wear SLs for DED may have an increased likelihood of experiencing MDF that would need to be proactively managed. This proactive management can include educating patients on lens cleaning techniques, optimizing lens parameters, and addressing underlying inflammation.

4.2. Poor Wettability

• Another challenge of fitting SLs in the DED population is poor lens surface wettability. Wettability refers to the ability of the tear film to spread evenly across the lens surface.

• Contact lens wettability describes the ability of a liquid to spread onto and maintain contact with a surface $[65]$. Good wettability is essential for maintaining a stable and comfortable tear film.

• Poor wettability indicates a non-stable tear film distribution over a contact lens surface $[66]$ and is associated with transient blurred vision, contact lens intolerance, and symptoms of discomfort and dryness in the soft contact lens literature $[67–69]$. These symptoms can significantly impact patient satisfaction and compliance.

• In DED cases where meibomian gland dysfunction (MGD) is a contributing factor, excess deposition of meibum onto the ocular surface can reduce wettability $[70]$. MGD is a common cause of evaporative dry eye, and the abnormal meibum can interfere with tear film stability.

• In the context of SLs, poor wettability would manifest as a non-sharp light reflection on the lens surface and often has a “greasy” appearance $[71]$. This can lead to visual disturbances and discomfort.

• Clinically, patients with DED and other OSDs are more prone to suffer from poor wettability, suggesting another barrier to successful SL implementation in this population $[71]$. Addressing wettability issues is crucial for improving patient comfort and visual outcomes.

4.3. Patient Expectations

• Managing patient expectations may be more challenging when fitting DED patients with SLs. It is important to set realistic goals and ensure that patients understand the potential benefits and limitations of SL wear.

• DED patients without associated corneal irregularities or other forms of OSD often have a lower level of satisfaction with SL wear compared to patients who require SLs for visual rehabilitation. This may be due to the fact that SLs primarily address dry eye symptoms rather than providing significant visual correction.

• A study involving 178 patients reported that those with DED ranked comfort and overall satisfaction lower than patients with other conditions, such as keratoconus, penetrating keratoplasty, irregular astigmatism, and corneal dystrophy $[72]$. This highlights the importance of addressing specific concerns and challenges faced by DED patients.

• The lower satisfaction scores were partly attributed to MDF $[72]$ and deposits on the lens, which can be mitigated by increasing the frequency of lens cleaning $[73]$. Proper lens care and maintenance are essential for maximizing comfort and visual clarity.

• A third reason for dissatisfaction could be related to issues with the conjunctiva, which is not entirely covered by a SL. For example, conjunctival sensitivity $[74]$ and conjunctivochalasis $[75]$ have been shown to be associated with DED signs and symptoms. These conditions can contribute to overall discomfort and irritation.

• A final reason may be reduced motivation to wear SLs when the visual benefits are not immediately evident, especially during the initial fitting period $[76]$. Patients may become discouraged if they do not experience significant visual improvement early on.

• At a 12-month follow-up, more subjects with regular corneas dropped out of SL wear compared to subjects with irregular corneas, and the primary reason for dropout was handling issues because vision with SLs was comparable to their habitual correction $[76]$. This underscores the importance of providing thorough training and support to patients to ensure proper lens handling and care.

• More studies are needed to better understand patient satisfaction and the reasons for dissatisfaction in this particular patient population. Identifying and addressing these factors can help improve patient outcomes and increase long-term success with SL wear.

5. Specific Considerations of SL Fitting in DED Patients

• Successful management of DED patients with SLs depends on several factors, including the management of existing OSD, the use of rewetting drops, the selection of appropriate lens parameters, and careful consideration of the filling solution.

• When fitting DED patients with SLs, practitioners need to recognize that SLs can only alleviate the symptoms of dryness but will not treat the underlying causes of dryness. Addressing the root causes of DED is essential for long-term management.

• If the underlying cause of dryness is inflammation, therapeutic management of existing OSD needs to be initiated either before or concurrently with SL wear to ensure fitting success. Controlling inflammation can improve tear film stability and reduce dry eye symptoms.

• Currently, no studies have investigated the efficacy of rewetting drops used over SLs. However, similar to the advice given to soft contact lens wearers, non-preserved and contact lens-compatible rewetting drops are generally preferred over preserved and non-contact lens-compatible options $[77]$. Non-preserved drops are less likely to cause irritation, and contact lens-compatible drops are designed to work effectively with lens materials.

• When the SL alone does not provide enough symptomatic relief for DED, some practitioners recommend mixing autologous serum with non-preserved saline in the post-lens tear film with anecdotal success, particularly if the patient is already being treated with autologous serum. Autologous serum contains growth factors and other components that can promote corneal healing and reduce inflammation.

• A case report discussed the resolution of persistent epithelial defects in a case of severe neurotrophic keratitis by adding autologous serum to the SL fluid reservoir $[78]$, but there is currently limited evidence in the literature to support the widespread use of this approach. Further research is needed to determine the efficacy and safety of using autologous serum with SLs.

• When designing the initial SL, diameter is often the first parameter to be determined $[79]$. However, there is no consensus on what diameter works best for DED patients without associated corneal irregularities or other forms of OSD. The optimal diameter may depend on individual patient factors and fitting goals.

• Fitting SLs less than 15 mm in diameter may be attractive because the cornea is regular, and small-diameter SLs are generally easier for novice practitioners to fit and for patients to handle $[80]$. However, smaller lenses may provide less conjunctival coverage, which could impact overall dryness sensation.

• Experienced practitioners may prefer larger-diameter SLs for the greater conjunctival coverage, which could contribute to a reduced sensation of dryness and decreased conjunctival staining, as illustrated in Figure 1. Larger lenses may provide a more stable and protective environment for the ocular surface.

• Ensuring proper edge alignment is also critical for fitting success. A tight or loose edge may exacerbate ocular irritation in DED patients $[81]$. Therefore, careful attention should be paid to troubleshooting edge alignment problems, such as edge lift, conjunctival impingement, or conjunctival blanching, by thoroughly assessing the settled SL edge on the eye.

• Furthermore, the observation of an indentation ring or conjunctival staining after lens removal may indicate a tight edge $[71]$, while the observation of sectorial fluorescein seepage into the post-lens tear film upon fluorescein instillation may indicate subtle edge lift $[71]$. These signs can help guide adjustments to the lens edge design.

• If the SL design allows, incorporating toric, quadrant-specific, or free-form haptics can further optimize alignment. Research on anterior segment shape has demonstrated that only 5.7% of scleras are spherical $[82]$, highlighting the importance of customizing the lens haptics to match the individual scleral shape.

• To minimize MDF, in addition to managing any existing OSD, lens parameters and filling solutions can be optimized. While studies have been inconclusive, the general recommendation is to avoid excessive fluid reservoir thickness (FRT) in any zone of the SL, including the central, mid-peripheral, and limbal areas $[63,71]$. Excessive FRT provides space for debris to accumulate and may induce additional inflammation on the ocular surface $[63]$.

• Proper edge alignment is also essential, as a loose edge may allow the influx of debris, and a tight edge may exacerbate ocular surface inflammation $[63]$. Addressing edge issues can help improve tear film stability and reduce MDF.

• When considering alternative filling solutions, a non-preserved solution that mimics the pH and ionic composition of natural tears may be beneficial. Such solutions may help maintain tear film homeostasis and reduce irritation.

• A study in 22 SL wearers showed a non-statistically significant reduction in MDF grading on OCT images with this alternative filling solution $[83]$. However, the median OSDI scores and VAS scores for dryness, grittiness/foreign body sensation, burning/stinging, and overall pain/discomfort were significantly improved when this alternative solution was used $[83]$, suggesting a potential benefit in terms of subjective symptoms.

• Finally, some practitioners have reported reduced MDF by adding high-viscosity, non-preserved artificial tears to the post-lens tear film $[81]$, although no studies have formally investigated the efficacy of this approach. The increased viscosity may help trap debris and prevent it from accumulating in the central visual zone.

• If poor wettability is observed, the practitioner should first ensure that the issue is not due to laboratory defects or inadequate lens conditioning with a proper multipurpose solution before dispensing the lens to the patient $[84]$. Proper lens cleaning and conditioning are essential for maintaining lens surface wettability.

• Moreover, a polyethylene glycol (PEG)-based surface coating may be applied to improve wettability $[85]$. PEG coatings can create a hydrophilic surface that attracts and retains moisture, improving tear film stability.

• In a study involving 21 SL wearers with DED, the application of the Tangible Hydra-PegTM (Tangible Science LLC, Menlo Park, CA, USA) surface coating was associated with statistically significant reductions in lens discomfort, DED symptoms, corneal sodium fluorescence staining, tear break-up time, and frequency of MDF $[85]$. This suggests that PEG coatings can offer multiple benefits for DED patients wearing SLs.

6. Conclusions

• Despite the current lack of extensive evidence in the published literature to definitively support fitting SLs in DED patients without associated corneal irregularities or other forms of OSD, practitioners are increasingly offering SLs in this patient population due to the numerous potential benefits, while remaining mindful of the challenges.

• More comprehensive and well-designed studies are needed to further demonstrate the benefits of SLs in DED patients who do not have concurrent corneal diseases. These studies should focus on evaluating the impact of SLs on both subjective symptoms and objective clinical signs of DED.

• Until such evidence becomes available, the use of SLs in early-to-moderate DED management should be approached with caution and considered within the context of the existing DED treatment hierarchy. A thorough assessment of individual patient needs and careful consideration of potential risks and benefits are essential for making informed clinical decisions.