Silicone Hydrogel Contact Lenses and the Ocular Surface

doi:10.1016/S1542-0124(12)70262-8

The Ocular Surface

Volume 4, Issue 1, January 2006, Pages 24-43

https://doi.org/10.1016/S1542-0124(12)70262-8 Get rights and content

Abstract

For 30 years, contact lens research focused on the need for highly oxygen-permeable (Dk) soft lens materials. High Dk silicone hydrogel contact lenses, made available in 1999, met this need. The purpose of this review is to examine how silicone hydrogel lens wear affects the ocular surfaces and to highlight areas in which further research is needed to improve biocompatibility. Silicone hydrogel lenses have eliminated lens-induced hypoxia for the majority of wearers and have a less pronounced effect on corneal homeostasis compared to other lens types; however, mechanical interaction with ocular tissue and the effects on tear film structure and physiology are similar to that found with soft lens wear in general. Although the ocular health benefits of silicone hydrogel lenses have increased the length of time lenses can be worn overnight, the risk of infection is similar to that found with other soft lens types, and overnight wear remains a higher risk factor for infection than daily wear, regardless of lens material. Future contact lens research will focus on gaining a better understanding of the way in which contact lenses interact with the corneal surface, upper eyelid, and the tear film, and the lens-related factors contributing to infection and inflammatory responses.

References (210)

J Wolosin et al.
Stem cells and differentiation stages in the limbo-corneal epithelium
Prog Retinal Eye Res
(2000)
V Puangsricharern et al.
Cytologic evidence of corneal diseases with limbal stem cell deficiency
Ophthalmology
(1995)
R Lavker et al.
Corneal epithelial stem cells at the limbus: looking at some old problems from a new angle
Exp Eye Res
(2004)
J Auran et al.
Scanning slit confocal microscopic observation of cell morphology and movement within the normal human anterior cornea
Ophthalmology
(1995)
NA Brennan et al.
A 1-year prospective clinical trial of Balafilcon A (PureVision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule
Ophthalmology
(2002)
PM Ladage et al.
Effects of rigid and soft contact lens daily wear on corneal epithelium, tear lactate dehydrogenase, and bacterial binding to exfoliated epithelial cells
Ophthalmology
(2001)
HD Cavanagh et al.
Effects of daily and overnight wear of a novel hyper oxygen-transmissible soft contact lens on bacterial binding and corneal epithelium: a 13-month clinical trial
Ophthalmology
(2002)
M Imayasu et al.
The relation between contact lens transmissibility and binding of Pseudomonas aeruginosa to the cornea after overnight wear
Ophthalmology
(1994)
O Schein et al.
The incidence of microbial keratitis among wearers of a 30-day silicone hydrogel extended wear contact lens
Ophthalmology
(2005)
J Morrison et al.
Anterior collateral circulation in the primate eye
Am Acad Ophthalmol
(1983)

E Papas

On the relationship between soft contact lens oxygen transmissibility and induced limbal hyperaemia

Exp Eye Res

(1998)

A Kvanta et al.

Expression of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF) in inflammation-associated corneal neovascularization

Exp Eye Res

(2000)

T Kato et al.

Diminished corneal angiogenesis in gelatinase A-deficient mice

FEBS Letts

(2001)

D Sims

The pericyte - a review

Tissue Cell

(1986)

PR Sankaridurg et al.

Adverse events with extended wear of disposable hydrogels: results for the first 13 months of lens wear

Ophthalmology

(1999)

MR Allansmith et al.

Giant papillary conjunctivitis in contact lens wearers

Am J Ophthalmol

(1977)

BA Holden et al.

Effects of long-term extended contact lens wear on the human cornea

Invest Ophthalmol Vis Sci

(1985)

BA Holden et al.

The vascular response to long-term extended contact lens wear

Clin Exp Optom

(1986)

BA Holden et al.

Critical oxygen levels to avoid corneal edema for daily and extended wear contact lenses

Invest Ophthalmol Vis Sci

(1984)

A Huang et al.

Paracellular permeability of corneal and conjunctival epithelia

Invest Ophthalmol Vis Sci

(1989)

C Jenkins et al.

Limbal transplantation in the management of chronic contact lens-asociated epitheliopathy

Eye

(1993)

L Lim et al.

Laser in situ keratomileusis treatment for myopia in a patient with partial limbal stem cell deficiency

Eye Contact Lens

(2005)

S Tseng et al.

Amniotic membrane transplantation with or without limbal allografts for corneal surface reconstruction in patients with limbal stem cell deficiency

Arch Ophthalmol

(1998)

RA Thoft et al.

The X, Y, Z hypothesis of corneal epithelial maintenance

Invest Ophthalmol Vis Sci

(1983)

H Ren et al.

Apoptosis in the corneal epithelium

Invest Ophthalmol Vis Sci

(1996)

M Covey et al.

Hypoxic effects on the anterior eye of high Dk soft contact lens wearers are negligible

Optom Vis Sci

(2001)

SE Nilsson

Seven-day extended wear and 30-day continuous wear of high oxygen transmissibility soft silicone hydrogel contact lenses: a randomized 1-year study of 504 patients

CLAO J

(2001)

J Stern et al.

Comparison of the performance of 6- or 30-night extended wear schedules with silicone hydrogel lenses over 3 years

Optom Vis Sci

(2004)

HD Cavanagh

The effects of low- and hyper-Dk contact lenses on corneal epithelial homoeostasis

Ophthalmol Clin N Am

(2003)

PM Ladage et al.

Effects of eyelid closure and disposable and silicone hydrogel extended contact lens wear on rabbit corneal epithelial proliferation

Invest Ophthalmol Vis Sci

(2003)

PM Ladage et al.

Vertical movement of epithelial basal cells toward the corneal surface during use of extended-wear contact lenses

Invest Ophthalmol Vis Sci

(2003)

DJ O'Leary et al.

Size and number of epithelial cells washed from the cornea after contact lens wear

Optom Vis Sci

(1998)

DH Ren et al.

The relationship between contact lens oxygen permeability and binding of Pseudomonas aeruginosa to human corneal epithelial cells after overnight and extended wear

CLAO J

(1999)

DH Ren et al.

Adaptive effects of 30-night wear of hyper-O₂ transmissible contact lenses on bacterial binding and corneal epithelium: a 1-year clinical trial

Ophthalmology

(2002)

K Yamamoto et al.

Effect of eyelid closure and overnight contact lens wear on viability of surface epithelial cells in rabbit cornea

Cornea

(2002)

K Yamamoto et al.

Effects of low and hyper Dk rigid gas permeable contact lenses on Bcl-2 expression and apoptosis in the rabbit corneal epithelium

CLAO J

(2001)

L Li et al.

Annexin V binding to rabbit corneal epithelial cells following overnight contact lens wear or eyelid closure

CLAO J

(2002)

F Stapleton et al.

Short term wear of high Dk soft contact lenses does not alter corneal epithelial cell size or viability

Br J Ophthalmol

(2001)

F Stapleton et al.

Effect of long term wear of highly oxygen permeable contact lenses on corneal epithelial cells [ARVO Abstract]

Invest Ophthalmol Vis Sci

(2002)

PM Ladage et al.

Proliferation rate of rabbit corneal epithelium during overnight rigid contact lens wear

Invest Ophthalmol Vis Sci

(2001)

BA Holden et al.

The significance of the microcyst response: a review

Optom Vis Sci

(1991)

RL Terry et al.

CCLRU standard for success of daily and extended wear contact lenses

Optom Vis Sci

(1993)

S Hickson et al.

Prevalence of idiopathic corneal anomalies in a non contact lens-wearing population

Optom Vis Sci

(1997)

SG Zantos

Cystic formations in the corneal epithelium during extended wear of contact lenses

Int Contact Lens Clin

(1983)

L Keay et al.

Microcysts: clinical significance and differential diagnosis

Optometry

(2001)

L Keay et al.

Microcyst response to high Dk/t silicone hydrogel contact lenses

Optom Vis Sci

(2000)

RC Tripathi et al.

Ultrastructural study of non-traumatic recurrent corneal erosion

Br J Ophthalmol

(1972)

JP Bergmanson

Histopathological analysis of the corneal epithelium after contact lens wear

J Am Optom Assoc

(1987)

MC Madigan

Cat and monkey as models for extended hydrogel contact lens wear in humans. PhD thesis

(1989)

M Millodot

Effect of soft lenses on corneal sensitivity

Acta Ophthalmol

(1974)

Cited by (173)

Behaviour of hTERT in the tears of neophyte contact lens wearers during the sleep/wake cycle
2023, Contact Lens and Anterior Eye
To investigate the behaviour of telomerase reverse transcriptase (hTERT) in the tears of healthy neophyte contact lenses-wearing individuals during the sleep/wake cycle. A subsequent aim was to investigate whether hTERT behaviour was associated with inflammatory mediators interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) in tears.
Flush tears were collected from 19 healthy, non-contact lens-wearing participants (11 males, 8 females, mean age 31.9 ± 5.7 years), before and during contact lens wear. Tears were collected at noon, before sleep and upon awakening and levels of hTERT, IL-6 and TNF-α, were determined using enzyme-linked immunosorbent assays (ELISA).
hTERT levels (median [interquartile range]) during contact lens wear were significantly higher before sleep (436.5 (263.9 – 697.7) ng/ml compared to the same time point without contact lenses (256.1 (0.0 – 590.9) ng/ml (p = 0.01). There was no difference between contact lens wear (851.3 [353.2 – 2109.9]) ng/ml, and no wear (1091.0 [492.3 – 3045.4]) ng/ml, upon awakening (p = 0.94). A significant increase was found upon awakening compared to before sleep, irrespective of the presence of a contact lens (p = 0.02). IL-6 and TNF-α levels in tears were below the limit of detection.
The study showed that hTERT increases after a contact lens is placed on the eye, but this change is small, compared to the impact of overnight eye closure. Taken together with the lack of responses of the inflammatory markers monitored at the same time points, this may suggest that hTERT can respond both to low-level stress stimuli acting on the ocular surface, and to situations where inflammation is a likely factor.
Recent advances of smart materials for ocular drug delivery
2023, Advanced Drug Delivery Reviews
Owing to the variety and complexity of ocular diseases and the natural ocular barriers, drug therapy for ocular diseases has significant limitations, such as poor drug targeting to the site of the disease, poor drug penetration, and short drug retention time in the vitreous body. With the development of biotechnology, biomedical materials have reached the “smart” stage. To date, despite their inability to overcome all the aforementioned drawbacks, a variety of smart materials have been widely tested to treat various ocular diseases. This review analyses the most recent developments in multiple smart materials (inorganic particles, polymeric particles, lipid-based particles, hydrogels, and devices) to treat common ocular diseases and discusses the future directions and perspectives regarding clinical translation issues. This review can help researchers rationally design more smart materials for specific ocular applications.
An effective DLP 3D printing strategy of high strength and toughness cellulose hydrogel towards strain sensing
2023, Carbohydrate Polymers
Photocurable 3D printing technology has outperformed extrusion-based 3D printing technology in material adaptability, resolution, and printing rate, yet is still limited by the insecure preparation and selection of photoinitiators and thus less reported. In this work, we developed a printable hydrogel that can effectively facilitate various solid or hollow structures and even lattice structures. The chemical and physical dual-crosslinking strategy combined with cellulose nanofibers (CNF) significantly improved the strength and toughness of photocurable 3D printed hydrogels. In this study, the tensile breaking strength, Young's modulus, and toughness of poly(acrylamide-co-acrylic acid)_D/cellulose nanofiber (PAM-co-PAA)_D/CNF hydrogels were 375 %, 203 % and 544 % higher than those of the traditional single chemical crosslinked (PAM-co-PAA)_S hydrogels, respectively. Notably, its outstanding compressive elasticity enabled it to recover under 90 % strain compression (about 4.12 MPa). Resultantly, the proposed hydrogel can be utilized as a flexible strain sensor to monitor the motions of human movements, such as the bending of fingers, wrists, and arms, and even the vibration of a speaking throat. The output of electrical signals can still be collected through strain even under the condition of energy shortage. In addition, photocurable 3D printing technology can provide customized services for hydrogel-based e-skin, such as hydrogel-based bracelets, fingerstall, and finger joint sleeves.
Silk-elastinlike protein-based hydrogels for drug delivery and embolization
2022, Advanced Drug Delivery Reviews
Silk-Elastinlike Protein-Based Polymers (SELPs) can form thermoresponsive hydrogels that allow for the generation of in-situ drug delivery matrices. They are produced by recombinant techniques, enabling exact control of monomer sequence and polymer length. In aqueous solutions SELP strands form physical crosslinks as a function of temperature increase without the addition of crosslinking agents. Gelation kinetics, modulus of elasticity, pore size, drug release, biorecognition, and biodegradation of SELP hydrogels can be controlled by placement of amino acid residues at strategic locations in the polymer backbone. SELP hydrogels have been investigated for delivery of a variety of bioactive agents including small molecular weight drugs and fluorescent probes, oligomers of glycosaminoglycans, polymeric macromolecules, proteins, plasmid DNA, and viral gene delivery systems. In this review we provide a background for use of SELPs in matrix-mediated delivery and summarize recent investigations of SELP hydrogels for controlled delivery of bioactive agents as well as their use as liquid embolics.
Effects of contact lens wear on tear inflammatory biomarkers
2022, Contact Lens and Anterior Eye
This review article intends to critically review the available literature relating to the behavior of tear-borne inflammatory biomarkers during contact lens wear.
The workflow protocol followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement recommendations.
An exhaustive search was carried out using the PubMed database. The analysis included a list of 34 eligible clinical trials: Thirty addressed the use of soft contact lenses, three focused on rigid gas permeable lenses; and one on scleral lenses.
The biomarkers’ presence was described as changes in the molecular concentration compared to control groups – non-contact lens wearers – or baseline measurements.
Contact lens wear inflates the concentration of several inflammatory molecules in tears. Most relevant changes were found for IL-1β, IL-6, IL-8, IL-17, LTB₄, and MMP-9.
The use of rigid gas permeable lenses seems to produce a more robust sub-clinical inflammatory response than soft contact lenses, with significant contributions of IL-8, MMP-9, and EGF.
Reusable lenses that are worn continuously or on a daily modality are more likely to raise the expression of biomarkers compared to daily disposables.
Mechanical trauma, hypoxia, and wearing schedules may be associated with a distinct sub-clinical inflammatory response in contact lens wearers. The relationship between these responses and contact lens-induced discomfort remains unclear, as the existing scientific evidence is still scarce.
More clinical studies are still needed to prove the impact of reverse geometry and scleral lens wear on the behavior of tear-borne biomarkers.
Transient and steady state viscoelastic crack propagation in a double cantilever beam specimen
2022, International Journal of Mechanical Sciences
Crack growth in viscoelastic materials is understood with the use of cohesive models, or steady state theories which focus on viscoelastic dissipation. We consider a double cantilever beam (DCB) specimen under a remote constant pure moment, which is initially suddenly applied to the beams. It is shown that the response to the applied moment rapidly reaches a steady state in terms of crack propagation speed. In contrast, it is shown that the external work rate, contributing to fracture energy, stored elastic energy and viscous dissipation, has a transient that possibly lasts a significantly longer time. The dissipation rate increases with speed for a standard material, reaching a limit governed by the ratio of instantaneous to relaxed modulus. However, the initial dissipation rate at low crack propagation speeds can be orders of magnitude larger than the latter limit, and depends on the ratio between the initial crack size and the fracture process zone size, a regime which we define ultratough. For thin beams, we do not find any evidence, even in the steady state, of the dissipation-based theories’ suggestion of a reduced maximum load and then of an unstable regime of decreasing load with speed.

View all citing articles on Scopus

All authors are supported in part by the Australian Federal Government through the Cooperative Research Centre Scheme.

The authors have no commercial interest in any concept or product discussed in this article.

Single copy reprint requests should be sent to: Deborah F. Sweeney (address below)

Abbreviations are printed in boldface where they first appear with their definitions.

View full text

Clinical ScienceGary N. Foulks, MD, Section EditorSilicone Hydrogel Contact Lenses and the Ocular Surface

Abstract

Prog Retinal Eye Res

Ophthalmology

Exp Eye Res

Ophthalmology

Ophthalmology

Ophthalmology

Ophthalmology

Ophthalmology

Ophthalmology

Am Acad Ophthalmol

Exp Eye Res

Exp Eye Res

FEBS Letts

Tissue Cell

Ophthalmology

Am J Ophthalmol

Effects of long-term extended contact lens wear on the human cornea

Invest Ophthalmol Vis Sci

The vascular response to long-term extended contact lens wear

Clin Exp Optom

Critical oxygen levels to avoid corneal edema for daily and extended wear contact lenses

Invest Ophthalmol Vis Sci

Paracellular permeability of corneal and conjunctival epithelia

Invest Ophthalmol Vis Sci

Limbal transplantation in the management of chronic contact lens-asociated epitheliopathy

Eye

Laser in situ keratomileusis treatment for myopia in a patient with partial limbal stem cell deficiency

Eye Contact Lens

Amniotic membrane transplantation with or without limbal allografts for corneal surface reconstruction in patients with limbal stem cell deficiency

Arch Ophthalmol

The X, Y, Z hypothesis of corneal epithelial maintenance

Invest Ophthalmol Vis Sci

Apoptosis in the corneal epithelium

Invest Ophthalmol Vis Sci

Hypoxic effects on the anterior eye of high Dk soft contact lens wearers are negligible

Optom Vis Sci

Seven-day extended wear and 30-day continuous wear of high oxygen transmissibility soft silicone hydrogel contact lenses: a randomized 1-year study of 504 patients

CLAO J

Comparison of the performance of 6- or 30-night extended wear schedules with silicone hydrogel lenses over 3 years

Optom Vis Sci

The effects of low- and hyper-Dk contact lenses on corneal epithelial homoeostasis

Ophthalmol Clin N Am

Effects of eyelid closure and disposable and silicone hydrogel extended contact lens wear on rabbit corneal epithelial proliferation

Invest Ophthalmol Vis Sci

Vertical movement of epithelial basal cells toward the corneal surface during use of extended-wear contact lenses

Invest Ophthalmol Vis Sci

Size and number of epithelial cells washed from the cornea after contact lens wear

Optom Vis Sci

The relationship between contact lens oxygen permeability and binding of Pseudomonas aeruginosa to human corneal epithelial cells after overnight and extended wear

CLAO J

Adaptive effects of 30-night wear of hyper-O2 transmissible contact lenses on bacterial binding and corneal epithelium: a 1-year clinical trial

Ophthalmology

Effect of eyelid closure and overnight contact lens wear on viability of surface epithelial cells in rabbit cornea

Cornea

Effects of low and hyper Dk rigid gas permeable contact lenses on Bcl-2 expression and apoptosis in the rabbit corneal epithelium

CLAO J

Annexin V binding to rabbit corneal epithelial cells following overnight contact lens wear or eyelid closure

CLAO J

Short term wear of high Dk soft contact lenses does not alter corneal epithelial cell size or viability

Br J Ophthalmol

Effect of long term wear of highly oxygen permeable contact lenses on corneal epithelial cells [ARVO Abstract]

Invest Ophthalmol Vis Sci

Proliferation rate of rabbit corneal epithelium during overnight rigid contact lens wear

Invest Ophthalmol Vis Sci

The significance of the microcyst response: a review

Optom Vis Sci

CCLRU standard for success of daily and extended wear contact lenses

Optom Vis Sci

Prevalence of idiopathic corneal anomalies in a non contact lens-wearing population

Optom Vis Sci

Cystic formations in the corneal epithelium during extended wear of contact lenses

Int Contact Lens Clin

Microcysts: clinical significance and differential diagnosis

Optometry

Microcyst response to high Dk/t silicone hydrogel contact lenses

Optom Vis Sci

Ultrastructural study of non-traumatic recurrent corneal erosion

Br J Ophthalmol

Clinical Science
Gary N. Foulks, MD, Section Editor
Silicone Hydrogel Contact Lenses and the Ocular Surface

Adaptive effects of 30-night wear of hyper-O₂ transmissible contact lenses on bacterial binding and corneal epithelium: a 1-year clinical trial