Even though the 2021 Global Specialty Lens Symposium was not in-person this year, it did not disappoint. Each session had amazing presentations from a variety of worldwide experts. The Scleral Lens Supersession was no exception.

RESEARCH UPDATE

Maria K. Walker, OD, MS, summarized key findings from notable scleral lens research. She discussed a wide range of topics, including oxygen and corneal morphology; conjunctival tissue changes; intraocular pressure (IOP); tear fluid properties; tear exchange and composition; and optics as well as a variety of case series and case reports.

Oxygen is a crucial factor to consider when fitting scleral lenses. Dr. Walker discussed several studies comparing three important modifiable features that influence corneal edema: lens thickness, material Dk, and fluid reservoir thickness.

In an early study, Pullum et al decreased the thickness of lenses manufactured in a 115-Dk material from 300 microns to 150 microns and found a 7% increase in corneal edema (1.33% to 1.43%); however, the fluid reservoir thickness was unknown.¹ In 2020, Dhallu et al increased the material Dk from 100 to 200 and found a 12% reduction in edema (0.55% to 0.48%) when the lens thickness was 350 microns and the fluid reservoir was approximately 325 microns.² In another 2020 study, Fisher et al decreased the fluid reservoir thickness from 487 microns to 144 microns in lenses that had a thickness of 300 microns and a material Dk of 141.³ They found a 62% reduction in corneal edema (1.81% to 0.69%). Dr. Walker opined that practitioners could realize the biggest return on investment, so to speak, in reducing the hypoxic stress on the cornea by altering the fluid reservoir thickness if the Dk is greater than 100 and the lens thickness is less than 400 microns. Nevertheless, these reported levels of edema are still well below the 4% physiological corneal edema.

In discussing studies pertaining to the conjunctiva and scleral lens wear, Dr. Walker noted that researchers have found no differences between superior and inferior goblet cell density in keratoconic eyes.⁴ In addition, Alonso-Caneiro et al found that 70% of compression occurs on the conjunctiva and episclera, and it is greatest in the superior quadrant, followed by the temporal, inferior, and nasal quadrants.⁵ There is no change to the sclera. Conjunctival compression rebound may take three hours and is less than 24 hours in most patients, possibly longer, but this needs further study.

The impact of scleral lens wear on intraocular pressure (IOP) was studied long before the introduction of modern GP scleral lenses. In the early 1950s, Huggert et al evaluated IOP on normal and glaucomatous eyes wearing glass scleral lenses and found a greater IOP increase in glaucomatous eyes.^6,7 In the 1960s, Miller et al found that glaucoma patients experienced a more rapid onset of corneal edema⁸ and an estimated negative pressure of 5 mmHg to 18 mmHg during scleral lens wear.⁹ According to Dr. Walker, it wasn’t until 2017—after McMonnies published a brief report hypothesizing that scleral lenses can increase IOP¹⁰—that interest in this topic increased. She further described a multitude of factors that can influence changes in IOP, including fluid intake, body or head orientation, eye position, exercise, respiration, heart rate, diurnal variation, and manipulation of the eyelids or globe. Table 1 summarizes recent studies evaluating IOP and scleral lens wear.^11-18 The take-home message, Dr. Walker said, is that variability exists in the methods and in the findings of 1 mmHg to 5 mmHg changes in IOP. In addition, no ideal method exists to measure IOP during scleral lens wear, and some populations may be more susceptible to increased IOP with scleral lens wear. She noted that more studies need to be performed, particularly with diseased eyes.

Midday fogging can be a challenge for patients who wear scleral lenses. In a Scleral Lenses in Current Ophthalmic Evaluation (SCOPE) survey study, researchers found no difference in midday fogging associated with lens diameter, solutions, or the number of removals per day.¹⁹ Dr. Walker suggested that lipids, likely originating from meibum, may be associated with midday fogging, although there are no-peer reviewed papers supporting this to date.

As scleral lens optics advance, wavefront-guided lenses likely will become more commonplace. A recent study reported that daily cleaning of these special lenses did not change their optics or their base curves.²⁰

Dr. Walker reviewed several recent case reports, including one that discussed the use of a peripheral segmented vault over a conjunctival inclusion cyst to prevent impingement over the elevation.²¹ In a case series looking at post-penetrating keratoplasty for keratoconic eyes, researchers found almost 3% edema over the central 6mm of the cornea, with most edema occurring inferiorly away from the center.²² Several reports described fitting patients who have glaucoma drainage devices or who are post-trabeculectomy.^23-25

TECHNOLOGY AND INNOVATION

John D. Gelles, OD, offered insights on the newest innovations and technology. He discussed instruments commonly used in scleral lens practice, including corneal placido disc topography, tomography, and wavefront aberrometry. The corneal topographer helps him evaluate scleral lens centration and tear film stability over the surface of a scleral lens while also measuring corneal shape. With tomography, he evaluates the scleral lens haptic and clearance and monitors overall corneal health. He uses wavefront aberrometry to measure optical as well as visual quality and effectiveness.

Lens material and Dk are important factors to consider when fitting scleral lenses. Most practitioners use materials with a Dk greater than 100. Dr. Gelles discussed two hyper-Dk materials: tisilfocon A, which has a reported Dk ranging from 180 to 189, and fluoroxyfocon A, a new material that has a reported Dk of 200.

Corneal edema, particularly in compromised corneas, is often discussed in the literature, and pachymetry (either manual or optical), corneal endothelial cell counts, and scleral lens wearing challenges help determine the effect of edema from scleral lenses. Figure 1 shows an example of microcystic corneal edema caused by scleral lens wear. Dr. Gelles discussed how to alleviate this effect by using hyper-Dk materials, channels, and fenestrations.

Diagnostic lenses have evolved from spherical to toric to quadrant-specific, typically available with prolate or oblate profiles. Dr. Gelles noted that empirical fitting has also evolved. While early lenses used brass molds made from impressions, modern techniques use prescription, keratometry measurements, and white-to-white diameter acquired from topography or tomography (for normal corneas). Scleral lens profilometry allows non-contact scleral topography to be transferred to a laboratory. Three-dimensional scanning of impression molds can also be used to transmit the shape data. Practitioners who do not have these diagnostic instruments and devices still benefit from the data that has been sent to manufacturers in the form of resulting design improvements and enhancements.

Dr. Gelles described the variety of optics that have evolved through the years, including spherical, aspheric/eccentric, toric, multifocal, decentered, and wavefront-guided. Wavefront scleral lens optics are derived by measuring the eye’s higher-order aberrations (HOAs) with an aberrometer while a patient is wearing a scleral lens, then mirroring the data to cancel the aberrations experienced by the patient. Dr. Gelles likens this to noise-canceling headphones. According to the literature, wavefront-guided scleral lenses could provide a 43% to 66% reduction in HOAs, with a one-to-two-line improvement in visual acuity.^26-28 Some potential challenges encountered when prescribing wavefront-guided lenses are media opacities, lens decentration, and the visual system dynamics, including the pupil, lens, and tear film.

According to Dr. Gelles, practitioners can look forward to more advances in technology, as several new patents are in process. These innovations include accommodating scleral lenses that have liquid crystals and energized fluid meniscus; adaptive optics; light-emitting lenses for therapeutic purposes such as seasonal affective disorder, myopia, light filtration, and polarization; biometric sensing (IOP, glucose, and osmolarity); drug-releasing (antihistamine, immunomodulators, IOP-lowering, and antibiotics); electric field (corneal wound healing and cell migration); wearable displays and cameras; and low-vision applications.

Scleral lenses may also play a role in corneal cross-linking, in which the riboflavin would be placed in the fluid reservoir to eliminate the dropping schedule and in which an ultraviolet (UV)-emitting LED matrix in the lens would provide alignment for the treatment despite eye movement and with the eyes open or closed.

Virtual technology is also advancing, Dr. Gelles reported. For example, an e-tablet that is connected to a slit lamp can transmit live images for review by an off-site practitioner. Binocular drone slit lamp technology, which has been validated in the literature,²⁹ allows for remote examination with minimal network latency. Practitioners wear a virtual reality headset for a stereoscopic view of patients’ eyes. Multiple companies are developing a headset evaluation device that can be used to examine the anterior and posterior segments with various cameras and illumination.

SCLERAL LENS FITTING MODALITIES

Sheila Morrison, OD, MS, addressed the question “Which scleral lens fitting modality should I use? Diagnostic? Digital? Impression molded?” Dr. Morrison practices in Canada, where all three of these modalities are available. She described the quandary that many practitioners face: “How do we, in clinical practice, use the right tools for the right tasks at the right times to keep our patients 20/happy 100% of the time?”

Many contact lens practitioners are accustomed to fitting corneal GP lenses using diagnostic, empirical, and customization methods. Similarly, practitioners who fit scleral lenses may use diagnostic fitting sets. Empirical fitting and customization options are also available for scleral lenses, and lens customization may dictate which modality to choose.

When customizing scleral lenses, Dr. Morrison considers power, scleral elevation differences, vaults and notches, channels and fenestrations, and HOA correction as well as materials, coatings, and treatments. She recommends staying current with all of the available customizations and which designs offer these options.

Dr. Morrison credits the manufacturers for developing improved diagnostic lenses that can be selected by measurement recommendations. This minimizes the uncertainty of “pulling a lens out of a hat” when selecting the first lens. A diagnostic lens enables practitioners to be detectives when placing a known shape on an eye that has an unknown shape, and it allows for elucidation of the nuances of the scleral shape.

The newest measurement tools are digital scans and impression molds. Digital scans, including optical coherence tomography, Placido ring extrapolation, Scheimpflug imaging, and profilometry, facilitate initial trial lens selection or empirical design. With careful training, staff members can take the first scan and use the software to select the first lens, which is helpful and saves time. By understanding how to interpret the scan, practitioners can determine whether a spherical or toric lens should be used.

While empirical fitting is not new in the world of contact lenses, it has become increasingly successful for scleral lens fitting. Dr. Morrison cautioned, however, that the scans are predominantly for shape and not for lens optics. A diagnostic lens is still required for over-refraction of a scleral lens.

Dr. Morrison advises practitioners who are new to scleral lens fitting to start with what they have and to do what they can. A cost-benefit assessment will help determine which direction to take and which instrumentation to acquire to meet their goals. When evaluating a patient, Dr. Morrison takes into consideration the pathology and shape of the eye and also the patient’s situation (time, money, location, and goals). She noted that a thorough assessment of total ocular health—anterior and posterior—before beginning is crucial. To that end, she performs corneal and scleral topography.

Dr. Morrison, who sees many patients who have extremely irregular corneas, described a monocular patient who had a proud, ectatic profile after three corneal transplants. An optimal fit was imperative to maintain the health and functionality of his only seeing eye. A conventional scleral lens would have resulted in extensive vaulting in the peripheral cornea and over the limbus. Dr. Morrison designed a freeform scleral lens from profilometry.

In a 2019 study, the Scleral Shape Study Group found that higher ectasia was usually associated with higher asymmetry and irregularity of scleral shape.³⁰ By customizing lenses for unique scleral shapes, Dr. Morrison stated, comfort can be increased while fogging and chair time can be decreased. Data-driven designs can apply to spherical, toric, quadrant-specific, and asymmetrical freeform designs as well. When encountering a major scleral lens obstacle such as a bleb or a glaucoma drainage device, she is more likely to use a freeform or an impression design rather than a conventional lens.

If a new patient had previous failed fits, Dr. Morrison may suggest a different lens modality or use the technology that she has available to update and enhance the current fit. She is always careful to discuss the office visits and scheduling needs. If a patient travels far for the visit, Dr. Morrison will scan a freeform lens or an impression mold, if possible, to reduce the number of office visits. Determining whether to scan or imprint a lens depends on the available lens features required for the patient. She recommends taking multiple scans to ensure optimal data, particularly if a patient lives far away. She also cautioned that ocular surface disease influences the scans, and profilometry requires a clear smooth surface. In addition, too much or too little fluorescein can result in an erroneous scan.

Patients love cutting-edge technology, and Dr. Morrison shares images with them, but diagnostic lenses are equally important. They provide visual endpoints, a preview of lens comfort, and they help determine whether pain can be attenuated. Table 2 summarizes the pros and cons of each fitting method.

Dr. Morrison concluded that each patient is unique, and decision-making is multifactorial. The digital world is here to stay, but all tools have their place for the best patient outcomes.

SPECIAL POPULATIONS

Christine W. Sindt, OD, closed the scleral lens supersession with a discussion of special populations.

What makes a population “special?” Some examples include:

• systemic disease such as Stevens-Johnson syndrome, graft-versus-host disease, and ocular cicatricial pemphigoid
• age (very young or very old)
• anatomical or physical abnormalities, which can be congenital or acquired, such as blebs and patch grafts
• neurotrophic disease (epithelial defects)
• developmental delays

In discussing the responsibilities that scleral lens practitioners have with regard to special populations, Dr. Sindt advised being proactive, recognizing problems early, and becoming familiar with all of the services that are available, including support groups, written materials, and non-eye-related groups. Knowing all available treatments and potential outcomes can serve many patients. Understanding the disease, its natural progression, and its usual course is important. Comanaging patients—OD/OD, OD/MD, pain management, or psychological/psychiatric counseling—has many advantages.

Be creative, Dr. Sindt advised, as scleral lenses offer benefits for special populations, including stability, less lens rotation, and less lens ejection. They are comfortable and provide an extended range of optical parameters and toricity while also providing a layer of protection.

When caring for patients who have special needs, practitioners may encounter some challenges specific to that population, such as communicating with patients and with multiple caregivers. A patient’s temperament may make fittings difficult, examinations may require anesthesia, and patients may be using multiple medications, including eye drops.

When working with infants and young patients, as well as with some older patients, Dr. Sindt likes to fill the lens with a lubricating gel, which allows for face-up application. While congenital corneal anesthesia is extremely rare (the onset is usually before the age of 3 years), Dr. Sindt notes that these patients require close monitoring, as they will never know when they have an abrasion.

She also emphasized the importance of examining the blink rate and Bell’s phenomenon in patients who have exposure keratopathy. If a patient has an incomplete blink but the eyes roll up completely, a scleral lens may not be necessary; close monitoring is all that is required.

To provide optimal comfort and protection for patients who have keratinized lid margins (Figure 2), practitioners need to be aware of where the scleral lens lands, Dr. Sindt noted. She also recommends close monitoring for frequent keratinization scraping.

Microcorneas and megalocorneas also pose fitting challenges. Standard lenses may decenter and land on the limbus or peripheral cornea, leaving a ring imprint of staining on a large cornea.

Patients in special populations may have glaucoma, which can result in buphthalmos. Patients who have glaucoma also may have tubes or trabeculectomies. For patients who have glaucoma drainage devices, Dr. Sindt recommends designing at least 350 to 400 microns of vault over the area of the device to prevent compression and erosion. With that much extra vaulting, air can easily intrude under the lens. She advises filling the lens with lubricating gel in the first week of lens wear.

In eyes that have limbal stem cell deficiency, determining the underlying cause of inflammation—whether it’s from ocular surface pathology or lack of protection—should factor into your approach. According to Dr. Sindt, this is an example of “knowing what you are fitting, why you are fitting, and the course of the disease.”

Persistent epithelial defects (Figure 3) are common in patients who have neurotrophic corneas; they can be resurfaced with a scleral lens. Dr. Sindt advises photography at every visit and antibiotic prophylaxis.

In cases of trauma, practitioners need to understand a patient’s needs. For some, the primary issue may not be vision but rather cosmesis.

SUMMARY

The GSLS Scleral Lens Supersession covered a variety of topics that appealed to new as well as to highly experienced scleral lens practitioners. Thank you to Drs. Walker, Gelles, Morrison, and Sindt, who shared their vast experience and imparted great clinical pearls. CLS

REFERENCES

1. Pullum KW, Hobley AJ, Davison C. 100+ Dk: does thickness make much difference? J Br Contact Lens Assoc. 1991 Jan;14:17-19.
2. Dhallu SK, Huarte ST, Bilkhu PS, Boychev N, Wolffsohn JS. Effect of Scleral Lens Oxygen Permeability on Corneal Physiology. Optom Vis Sci. 2020 Sep;97:669-675.
3. Fisher D, Collins MJ, Vincent SJ. Fluid reservoir thickness and corneal oedema during closed eye scleral lens wear: Experimental and theoretical outcomes. Cont Lens Anterior Eye. 2021 Feb;44:124-125.
4. Macedo-de-Araújo RJ, Serramito-Blanco M, van der Worp E, Carracedo G, González-Méijome JM. Differences between Inferior and Superior Bulbar Conjunctiva Goblet Cells in Scleral Lens Wearers: A Pilot Study. Optom Vis Sci. 2020 Sep;97:726-731.
5. Alonso-Caneiro D, Vincent SJ, Collins MJ. Morphological changes in the conjunctiva, episclera and sclera following short-term miniscleral contact lens wear in rigid lens neophytes. Cont Lens Anterior Eye. 2016 Feb;39:53-61.
6. Huggert A. Increase of the intraocular pressure when using contact glasses. Acta Ophthalmol. 1951 Dec;29:475-481.
7. Huggert A. The intraocular pressure in glaucomatous eyes following the use of contact lenses. Acta Ophthalmol (Copenh). 1953 Apr;31:141-152.
8. Miller D, Carroll JM. Corneal edema and scleral lenses. Int Ophthalmol Clin. 1968 Fall;8:623-635.
9. Miller D, Carroll JM, Holmberg A. Scleral lens cling measurement. Am J Ophthalmol. 1968 Jun;65:929-930.
10. McMonnies CW. Re: Evidence on scleral contact lenses and intraocular pressure. Clin Exp Optom. 2017 Mar;100:200.
11. Nau CB, Schornack MM, McLaren JW, Sit AJ. Intraocular Pressure After 2 Hours of Small-Diameter Scleral Lens Wear. Eye Contact Lens. 2016 Nov;42:350-353.
12. Vincent SJ, Alonso-Caneiro D, Collins MJ. Evidence on scleral contact lenses and intraocular pressure. Clin Exp Optom. 2017 Jan;100:87-88.
13. Aitsebaomo AP, Wong-Powell J, Miller W, Amir F. Influence of Scleral Lens on Intraocular Pressure. J Contact Lens Res Sci. 2019 Apr;3:e1-e9.
14. Michaud L, Samaha D, Giasson CJ. Intra-ocular pressure variation associated with the wear of scleral lenses of different diameters. Cont Lens Anterior Eye. 2019 Feb;42:104-110.
15. Cheung SY, Collins MJ, Vincent SJ. The impact of short-term fenestrated scleral lens wear on intraocular pressure. Cont Lens Anterior Eye. 2020 Dec;43:585-588.
16. Obinwanne CJ, Echendu DC, Agbonlahor O, Dike S. Changes in Scleral Tonometry and Anterior Chamber Angle after Short-term Scleral Lens Wear. Optom Vis Sci. 2020 Sep;97:720-725.
17. Fogt JS, Nau CB, Schornack M, Shorter E, Nau A, Harthan JS. Comparison of Pneumatonometry and Transpalpebral Tonometry Measurements of Intraocular Pressure during Scleral Lens Wear. Optom Vis Sci. 2020 Sep;97:711-719.
18. Walker MK, Pardon LP, Redfern R, Patel N. IOP and Optic Nerve Head Morphology during Scleral Lens Wear. Optom Vis Sci. 2020 Sep;97:661-668.
19. Schornack MM, Fogt J, Harthan J, et al. Factors associated with patient-reported midday fogging in established scleral lens wearers. Cont Lens Anterior Eye. 2020 Dec;43:602-608.
20. Wilting SM, Hastings GD, Nguyen LC, et al. Quantifying the Optical and Physical Consequences of Daily Cleaning on Conventional and Wavefront-guided Scleral Lenses. Optom Vis Sci. 2020 Sep;97:754-760.
21. Sherman SW, Cherny C, Suh LH. Epithelial Inclusion Cyst of the Bulbar Conjunctiva Secondary to Scleral Lens Impingement Managed With a MicroVault. Eye Contact Lens. 2020 Nov;46:e56-e58.
22. Kumar M, Shetty R, Khamar P, Vincent SJ. Scleral Lens-Induced Corneal Edema after Penetrating Keratoplasty. Optom Vis Sci. 2020 Sep;97:697-702.
23. Tanhehco T, Jacobs DS. Technological advances shaping scleral lenses: the Boston ocular surface prosthesis in patients with glaucoma tubes and trabeculectomies. Semin Ophthalmol. 2010 Sep-Nov;25:233-238.
24. Nguyen AH, Dastiridou AI, Chiu GB, Francis BA, Lee OL, Chopra V. Glaucoma surgical considerations for PROSE lens use in patients with ocular surface disease. Cont Lens Anterior Eye. 2016 Aug;39:257-261.
25. Elving-Kokke KH, Sas-Meertens MAV, de Beer FM, van Rijn LJ, de Boer JH, Visser E-S. The treatment of ocular hypotony after trabeculectomy with a scleral lens: a case series. Cont Lens Anterior Eye. 2019 Feb;42:123-126.
26. Sabesan R. Johns L, Tomashevskaya O, Jacobs DS, Rosenthal P, Yoon G. Wavefront-guided scleral lens prosthetic device for keratoconus. Optom Vis Sci. 2013 Apr;90:314-323.
27. Marsack JD, Ravikumar A, Nguyen C, et al. Wavefront-guided scleral lens correction in keratoconus. Optom Vis Sci. 2014 Oct;91:1221-1230.
28. Hastings GD, Applegate RA, Nguyen LC, Kauffman MJ, Hemmati RT, Marsack JD. Comparison of Wavefront-guided and Best Conventional Scleral Lenses after Habituation in Eyes with Corneal Ectasia. Optom Vis Sci. 2019 Apr;96:238-247.
29. Luna GL, Parel JM, Gonzalez A, et al. Validating the use of a stereoscopic robotized teleophthalmic drone slit lamp. Can J Ophthalmol. 2020 Oct 25;S0008-4182(20)30775-4.
30. DeNaeyer G, Sanders DR, Michaud L, et al. Correlation of Corneal and Scleral Topography in Cases with Ectasias and Normal Corneas. J Cont Lens Res Sci. 2019 May;3:e10-e20.