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Contact lenses
Published in Pablo Artal, Handbook of Visual Optics, 2017
Unfortunately, the physical nature of RGP lenses, and the way they must be fit to ensure tear exchange and mobility on the eye, renders them less desirable as a method for correcting wavefront aberrations of the eye through complex optical surfaces. GP lenses are designed to be very mobile on the eye, moving at least 1.0 mm with each blink and finding a position of rest with up to 1 mm difference relative to the optical axis of the eye following each blink (Knoll and Conway 1987). Hence, stabilizing a conventional GP lens, such that it repeatedly returns to the same horizontal and vertical location relative to the visual axis, without rotating around this axis and maintaining physiologically desirable tear exchange behind the lens, is very difficult. Scleral lenses, which rest primarily on the scleral surface beyond the limbal junction with the cornea, hold potential promise, as they are very stable in their location on the eye. However, lenses of this type require a greater degree of fitting skill and clinician/patient interaction to generate a clinically acceptable fitting, and at this time the marketplace worldwide has shown they are not a preferred option for a mainstream ophthalmic correction.
Sjögren's Disease
Published in Jason Liebowitz, Philip Seo, David Hellmann, Michael Zeide, Clinical Innovation in Rheumatology, 2023
Management of dry eye disease. A stepwise approach to the management of DED is recommended and is based on severity of symptoms and measures of ocular dryness (168). Topical cyclosporine drops were initially approved in 2003, but newer formulations (Cequa) are now available and the use of compounded solutions with higher drug concentration is more prevalent. In 2016, lifitegrast 5% ophthalmic solution was approved based on data from five randomized clinical trials. It acts via preventing recruitment and activation of T cells by targeting lymphocyte function-associated antigen-1 (169). Autologous serum tears can be compounded for severe DED. Their use is associated with relief that exceeds the lubrication effect when compared with artificial tears, although the therapeutic effect is short-lived (170). An intranasal stimulator of tear production was approved in 2017 but unfortunately was taken off the market in 2020 due to its high cost of manufacturing. The TrueTear® device stimulates the anterior ethmoid nerve, leading to increased lacrimation and improved symptoms (171). A significant proportion of SjD patients have meibomian gland dysfunction (MGD) in addition to inadequate tear production (172). This leads to tear film instability and increased evaporative tear loss. Traditionally, MGD is treated with eyelid hygiene, topical nonsteroidal anti-inflammatory agents, and antibiotics. Newer techniques seek to improve meibum secretion from the meibomian glands by decreasing its viscosity; these modalities include electronic heating devices, intense pulsed light therapy, and thermal pulsation (173, 174). Scleral lenses are an option for patients with dry eye symptoms refractory to other treatments; they completely vault the cornea, creating a liquid bandage that can lead to significant symptom relief (175).
What we know about the scleral profile and its impact on contact lens fitting
Published in Clinical and Experimental Optometry, 2023
Javier Rojas-Viñuela, Melanie J Frogozo, David P Piñero
The initial differences between individuals, and the asymmetric profile in different meridians of the same eye have been confirmed with the advent of these new devices. Furthermore, the Scleral Shape Study Group (SSSG) established a new classification for the scleral shape on which four different scleral profiles were defined15: (Figure 4) (1) 5.7% of scleras were spherical with differences between the lowest and highest sagittal height below 300 microns (Figure 4A); (2) 28.6% of eyes showed a scleral toric regular pattern with differences in sagittal height above 300 microns and with 180º periodicity between the lowest and the highest points (Figure 4B); (3) the largest profile group comprised 40.7% of the scleras and had elevations and depressions or a single large elevation (Figure 4C); (4) the remaining 26% were irregular, showing a toric pattern but with no 180º periodicity (Figure 4D).15 This study did not record whether the measured eyes were healthy or affected by ectasias or surgeries. However, the patients were candidate for prospective scleral lens fits. Thus, several irregular and pathological corneas could be expected among the analysed eyes.15 This is somehow relevant because some differences in the scleral profile of healthy and pathological eyes have been established.
Corneal ectasia with Stevens–Johnson syndrome
Published in Clinical and Experimental Optometry, 2021
Mukesh Kumar, Rohit Shetty, Vaitheeswaran G Lalgudi, David A Atchison, Stephen J Vincent
Isolated keratoconus can be managed by several types of contact lenses, from a soft toric in early stages to rigid gas permeable corneal and scleral lenses in more advanced stages. The presence of SJS with keratoconus adds a component of ocular surface disturbance in the form of severe dry eye, limbal stem cell deficiency, and vascularisation. In such cases, scleral lenses are an ideal treatment since they provide constant lubrication to the ocular surface and reduce corneal aberrations. Scleral lenses (PROSE) have been used in the past in keratoconus associated with SJS with satisfactory improvement in visual acuity and comfort.2 In isolated SJS patients without keratoconus, several studies have reported improvements in vision and ocular comfort following the use of corneo-scleral or scleral contact lenses.11–13
Are eye‐care practitioners fitting scleral contact lenses?
Published in Clinical and Experimental Optometry, 2020
Craig A Woods, Nathan Efron, Philip Morgan
Scleral lenses were, are and will continue to be, a lens design used for specialised situations, such as in the management of dry eye disease, ectasia and high ametropia. Increasing evidence in the peer‐reviewed literature provides confidence that this type of lens can be used successfully and that modern designs – smaller diameter and non‐fenestrated – are easier to fit than traditional larger diameter fenestrated designs. However, it is the view of the authors that – in respect of the claim of modern smaller scleral lenses being easier to fit – this may well be the case, but only in the hands of specialist fitters rather than general eye‐care practitioners. This is possibly also confirmed by the fact that, throughout the survey period, a higher proportion of patients were fit with orthokeratology lenses, which while also a specialist lens design, has a greater market share due to the larger role contact lenses play in the management of myopia progression, compared to ocular surface disease.