After the tsunami of scleral lens publications in the latter part of 2020 (see I-site newsletter November and December 2020), it is time to digest all of that and to reflect. Maybe this new study from the Kellogg Eye Center at the University of Michigan (US) sums it all up: The impact of scleral lens use on the rate of corneal transplantation for keratoconus. The study supports clinical evidence from corneal experts that patients’ access to scleral lenses reduces the risk of keratoplasty for patients with keratoconus. Scleral lenses can indeed delay and/or prevent corneal surgery in keratonus patients, with huge ecomonic and lifestyle benefits. Physicians should maximize the use of scleral or corneal GP lenses because patients who successfully use contact lenses have almost one-fifth the risk of undergoing keratoplasty. What a great way to start 2021. I-site newsletter started early last year with 'Hindsight is 20/20'. Let's not look back to last year too much. Happy new year to everyone, and off to new beginnings!

After the scleral lens turmoil of last year, it is good to see that corneal lenses do get their fair share of attention too. In Contact Lens Spectrum a number of interesting articles refer to various aspects of corneal lens fitting.

There is a growing resurgence of interest in corneal lenses, write Annie Chang and Timothy Edrington - due to myopia management but also because corneal lenses are being used to manage patients who have irregular corneas when reduced cost and ease of handling are desired. In their Spectrum article, they explain how to indentify four types of corneas based on fluorescein pattern evaluation. If patients are not correctable to 20/20 with manifest refraction and have large amounts of refractive astigmatism, confirming the type of cornea is helpful in determining the lens design and parameters. They identify 1) the 'Significantly Toric Regular Cornea,' with a dark horizontal band indicating a with-the-rule pattern. A toric-back-surface corneal GP lens would improve lens centration and comfort here. Exhibit #2 shows a spherical corneal lens on a patient who has keratoconus. This patient also exhibits large amounts of corneal toricity, but unlike the previous patient, the cornea is irregular. Rather than a dark horizontal band, a small circular area represents the apex of the cone. This is a 'three-point-touch' pattern. Number 3 is a pellucid marginal degeneration (PMD). PMD and keratoconus are both corneal ectasias, but PMD differs in that the location of protrusion is peripheral; when viewing the fluorescein pattern, the area of bearing is decentered inferiorly. Because the area of highest elevation is inferior, corneal lenses tend to decenter inferiorly, which requires a larger lens. Lastly (#4), a fluorescein pattern of a post-radial keratotomy cornea is shown, with varied areas of pooling and bearing that are unique from cornea to cornea. Because of the irregular topography, a larger-diameter lens can improve centration and allow for a larger optic zone.

There is a debate in the international community as to whether orthokeratology (OK) works as well in lower myopes for myopia control as it does in higher levels of myopia. The rationale behind this is that myopia research in general seems to indicate that higher 'near add' is needed for maximal effect. Correction of low myopia with orthokeratology may lead to relatively lower 'plus' values in the periphery. However, an editorial in myopiaprofile.com questions this assumption. In short, Kate Gifford states that there is currently no supportive evidence for OK being less effective in lower than in higher myopia. It should work similarly for myopia control regardless of baseline myopia. There is also no evidence, the editorial states, suggesting that multifocal soft lenses are comparatively more effective than orthokeratology lenses are for low myopia. In fact, the one direct comparison may indicate the opposite. To keep things simple, she suggests that both work, and eyecare practitioners should pick what lens option best suits their patient. Finally, the editorial states that the chief determinant of myopia progression is age - the sooner you start, the better the overall impact of myopia control will be on final axial length.

Although applied to scleral lenses, the outcome of this study could have implications for corneal lens surfaces as well:"Assessment of a Novel Lens Surface Treatment for Scleral Lens Wearers With Dry Eye". The investigators compared lens comfort and dry eye symptoms in scleral lens wearers fit with polyethylene glycol (PEG)-based surface-treated scleral lenses and with untreated sclerals. PEG–treated lens wear resulted in significantly improved lens comfort, dry eye symptoms, corneal staining, temporal conjunctival lissamine green staining, lid wiper epitheliopathy, conjunctival papillae, frequency of foggy vision, tear break-up time, and comfortable lens wear time compared with untreated wear. So in dry eye patients, it seems a good option to consider this novel surface treatment, as it could potentially provide improved comfort, reduced symptoms and reduced ocular surface compromise compared with untreated sclerals.

Lens depositing on rigid gas permeable surfaces can be a frustrating problem for both patients and eyecare providers. Attempts to address depositing usually include changes to patients’ cleaning regimen, lens material, surface treatments, coatings, or even lens fitting properties. While these changes can be helpful, sometimes they aren’t enough to fully eliminate stubborn depositing. While hydrogel lens deposits tend to be more protein-based, (R)GP lens surfaces attract more lipids, with silicone-based lenses even more so compared to (R)GPs containing fluorine. It is logical to think that the hypersecretory forms of meibomian gland dysfunction (MGD) may be more likely to lead to contact lens deposits than the obstructive or hyposecretive forms would, though this remains unconfirmed. Any type of MGD could cause abnormal lipid quality and/or quantity, and practitioners should address this area if (R)GP lens depositing is a persistent issue. In fact, if a hyposecretory form of MGD causes significant tear film instability, deposits may result from an imbalance of tear film components. In conclusion: rather than looking at the (R)GP lens to problem-solve depositing issues, it can be necessary to look at patients and their eyelids instead. With diligent efforts to improve and maintain meibomian gland function, patients will often find that 'clean lids make for clean lenses.'

Interestingly, Melanie Frogozo in 'pediatric and teens contact lens care' column in Contact Lens Spectrum touches on the same possiblity: describing scleral lenses to lift the eyelids as 'a road less travelled'. She describes a case of a 17-year-old Hispanic male with a history of traumatic levator dehiscence of the right eyelid. The patient underwent blepharoplasty surgery at the age of 13 years, with no improvement in cosmetic appearance. A large-diameter 19mm scleral contact lens fitted on the right eye provided the patient with satisfactory improvement in the appearance of his ptosis, while as a 'side effect' his vision was improved by correcting the corneal astigmatism present in that same eye. Hence: scleral lenses can provide cosmetic eyelid elevation and visual rehabilitation and are an alternative treatment modality for patients who would otherwise have to opt for ptosis surgery, with guarded prognosis.

i-site@netherlens.com.