41st Annual Contact Lens Report
Follow the links below to read the other articles from our 41st annual Contact Lens Report:Corneal Topography for Better Fitting
Even with healthy growth in the number of contact lens (CL) options on the market, one particular burden continues to dog the industry—contact lens discomfort (CLD).1-5
According to the Tear Film and Ocular Surface Society (TFOS) report on CLD, the only CL material-related factor that demonstrates correlation with CLD is coefficient of friction.6 However, until researchers agree upon an industry-standard methodology to measure friction of CL materials, this remains a difficult area to study. Other material-related factors, such as oxygen transmissibility, wettability, modulus and lens dehydration, only display weak links with CLD. Lens replacement frequency, lens design, thickness/bulk and edge configuration also show some relationship to CLD.5
Over the past few years, CL companies have debuted technologies aimed at developing lenses with surface and bulk properties that reduce discomfort. Some Silicone hydrogel (SiHy) materials even hope to address patient-related issues, such as digital eyestrain. This article reviews the latest SiHy materials that manufacturers hope will reduce patient discomfort as well as new CL materials and designs of other lens types.
|Fig. 1. This patient presented with a mechanical complication known as mucin balls (shown at high magnification on the right). Click image to enlarge. Photos: Jalaiah Varikooty, MSc, BMed|
SiHy Setbacks and Successes
This material now accounts for approximately 55% of all soft lens fits worldwide and 62% in the United States.7 Its increased oxygen transmissibility promised a reduction in the rate of corneal infections, but research shows the risk of microbial keratitis is similar regardless of lens material studied.8-12 In fact, several studies show that SiHy materials doubled the relative risk for infiltrative events.13-16 Studies also suggest that older generation SiHy materials provided only a minimal increase in comfort over conventional hydrogel (CH) materials.5,17 This was due to the incorporation of siloxane groups into SiHy lenses, which made them more hydrophobic and stiffer than CH materials, but led to issues related to poor lens wettability and mechanical complications.18-20 These mechanical complications included mucin balls (Figure 1), corneal erosions (Figure 2), superior epithelial arcuate lesions (Figure 3), epithelial flaps and CL-associated papillary conjunctivitis.21-26 The hydrophobic nature of certain SiHy materials tends to deposit high levels of certain lipids and increased denatured protein.27,28 Hence, several practitioners still choose to fit CH materials.
However, a newer generation of SiHy lenses were designed with these issues in mind. For instance, Air Optix plus with HydraGlyde (Alcon) incorporates two technologies—SmartShield Technology and HydraGlyde Moisture Matrix—which provide a combination of deposit protection and longer-lasting lens surface moisture.29 According to the manufacturer, lenses with “SmartShield technology” prevent silicone from reaching the surface of the CLs, which helps the lens surface retain moisture and resist deposition with the intention of maintaining comfort throughout the wearing period. “HydraGlyde Moisture Matrix” involves a block copolymer. One side of the HydraGlyde molecule adsorbs onto the contact lens; the other attracts additional moisture, which the manufacturer says results in an envelope of lasting lens surface wettability.
In August 2016, CooperVision announced the launch of a new SiHy lens, Avaira Vitality (CooperVision), in sphere and toric options, manufactured from fanfilcon A, which has a high water content (55%) and high oxygen permeability (Dk) and transmissibility level (Dk/t). This material also features a Class I ultraviolent (UV) protection rating, and it blocks more than 90% of long-wave and 99% of shortwave UV rays. In July, CooperVision introduced its Biofinity Energys (CooperVision), with digital device users in mind. According to the company, this comfilcon A-based lens has two novel elements: “digital zone optics,” which integrates multiple, front-surface, aspheric curves across the entire optical zone, distributing power evenly and simulating more positive power in the center of the lens; and “aquaform technology,” which has high oxygen transmissibility and low modulus, attracting and binding water.30
Table 1. Reusable Spherical Silicone Hydrogel Contact Lenses
|Manufacturer||USAN||Brand name||Replacement frequency & modality||Proprietary technology||Wetting Agent||Dk/t (-3.00D)||Modulus (Mpa)||Water content||BOZR (mm)||Diameter (mm)|
|Alcon||lotrafilcon A||Air Optix Night & Day Aqua||1 month DW or up to 30N CW||Surface treatment: plasma coating||Moisture agent in packaging solution (1% copolymer 845)||175||1.5||24%||8.4, 8.8||13.8|
|lotrafilcon B||Air Optix Aqua||1 month DW or up to 6N EW||Surface treatment: plasma coating||Moisture agent in packaging solution (1% copolymer 845)||138||1||33%||8.6||14.2|
|lotrafilcon B||Air Optix Aqua plus HydraGlyde||1 month DW or up to 6N EW||Surface treatment: plasma coating||Added HydraGlyde technology||138||1||33%||8.6||14.2|
|Bausch + Lomb||balafilcon A||PureVision||1 month DW or up to 30N CW||Surface treatment: plasma oxidation||None||101||1.1||36%||8.3, 8.6||14.0|
|balafilcon A||PureVision 2 HD||1 month DW or up to 30N CW||Surface treatment: plasma oxidation||None||130||1.1||36%||8.6||14.0|
|samfilcon A ||Ultra||1 month DW||MoistureSeal||Internal wetting agent: Polyvinyl pyrrolidone (PVP)||163||0.7||46%||8.5||14.2|
|CooperVision||comfilcon A||Biofinity||1 month DW or up to 7N CW||Aquaform technology||None||160||0.75||48%||8.6||14.0|
|enfilcon A||Avaira||2 week DW US||Aquaform technology||Integrated Polyethylene Glycol (PEG)||125||0.5||46%||8.4 (+ve); 8.5 (-ve)||14.2|
|fanfilcon A||Avaira Vitality||2 week DW US||Aquaform technology||None||110||0.6||55%||8.4||14.2|
|Johnson & Johnson Vision||senofilcon A||Acuvue Oasys||2 week DW or 6N EW||Hydraclear Plus||Internal wetting agent: PVP||147||0.72||38%||8.4, 8.8||14.0|
|galyfilcon A||Acuvue Advance||2 week DW||Hydraclear||Internal wetting agent: PVP||86||0.43||47%||8.3, 8.7||14.0|
|senofilcon C||Acuvue Vita||4 week DW||HydraMax||Internal wetting agent: PVP||147||Not available||41%||8.4, 8.8||14.0|
|Menicon||asmofilcon A||Premio (Miru 1 month)||Premio: 2 week DW or 6N EW; Miru 1 month DW||MeniSilk technology and Nanogloss surface coating||161||0.9||40%||8.3, 8.6||14.0|
In 2016, Johnson & Johnson Vision announced a monthly replacement SiHy lens, Acuvue Vita (senofilcon C). This lens material is designed to integrate beneficial lipids found in tears within the lens and also helps to maintain lens hydration with reduced evaporation, all in an effort to improve comfort. Johnson & Johnson Vision also launched Acuvue Oasys 1-Day with “HydraLuxe technology,”which uses a tear-infused design that mimics mucins to help support a stable tear film. The material has an enhanced network of tear-like molecules.
This new lens has an increased diameter to ensure full corneal limbus coverage during blinking and includes enlarged optics to help cover larger pupils in low lighting conditions (Tables 1 and 2).
In February 2016, Bausch + Lomb announced Ultra for Presbyopia, a monthly replacement SiHy lens that incorporates the company’s “MoistureSeal technology” and three-zone progressive design found in Biotrue OneDay for Presbyopia daily disposable CLs. The company says these lenses “maintain 95% of their moisture for up to 16 hours.”31 Bausch + Lomb’s website say the two-phase manufacturing process of these lenses retains moisture and delivers a highly wettable surface. Phase 1 combines long- and short-chain monomers to formulate a unique silicone backbone. In phase 2, the polyvinylpyrrolidone (PVP) grows around and throughout the silicone backbone. The high volume of PVP at the core is meant to provide moisture retention and the tightly compacted PVP at the surface delivers high wettability.
Menicon recently launched Rose K2 Soft CL design for the irregular cornea. Rose K lenses are a frequently prescribed lens design for the correction of keratoconus and irregular cornea conditions and are mostly rigid gas permeable lenses. The newly launched Rose K2 Soft design is a daily wear SiHy soft lens for irregular corneas, available as a three-month replacement lens. The Rose K2 Soft design features an aspheric back optic zone, front surface toricity and front surface aberration control. According to the company, Rose K2 Soft offers edge lift control, prism ballast stabilization and reverse geometry.32 Rose K2 Soft is available now in the United States from ABB Optical, Art Optical Contact Lens and Blanchard Contact Lens.
Table 2. Daily Disposable Spherical Silicone Hydrogel Contact Lenses
|Manufacturer||USAN||Brand name||Proprietary technology||Wetting agent||Dk/t (-3.00D)||Modulus (Mpa)||Water content||BOZR (mm)||Diameter (mm)|
|Alcon||delefilcon A||Dailies Total 1||Water gradient technology||None||156||0.63||33% core t>80% surface||8.5||14.1|
|CooperVision||stenfilcon A||MyDay||Smart Silicone||None||100||0.4||54%||8.4||14.2|
|somofilcon A||Clariti 1 Day||WetLoc technology||None||86||0.5||56%||8.6||14.1|
|Johnson & Johnson Vision||narafilcon A||1 Day Acuvue TruEye ||Hydraclear 1||Internal wetting agent: PVP||118||0.66||46%||8.5, 9.0||14.2|
|senofilcon A||Acuvue Oasys daily contact lens with Hydraluxe||Hydraluxe||Internal wetting agent: PVP||121||0.72||38%||8.5, 9.0||14.3|
Over the last decade, CL manufacturers have provided a variety of scleral contact lens (ScCL) designs that have a wide range of applications.33,34 Current ScCLs are manufactured using high Dk materials (e.g., fluorosilicone acrylate). Such materials aid in increasing oxygen supply to the cornea.
Asian patients’ corneas have a smaller horizontal visible iris diameter and are more prolate with a smaller palpebral fissure than Caucasians’ corneas.35 Blanchard designed a lens (Onefit A Scleral lens) to provide optimal limbal clearance and easier handling with a smaller diameter and an altered paracentral geometry.36 Blanchard also launched a new feature called XLC (Extra Limbal Clearance), to its Onefit Scleral Lens Platform to obtain additional limbal clearance, without increasing the lens diameter. In March 2016, Art Optical announced the availability of its new 16.5mm scleral lens, Ampleye. According to the company, this is designed to fully vault the cornea and limbus, without corneal involvement.37 In addition to a toric haptic, the lenses include a four-zone construction, providing independent zone adjustments for finite control of the lens fit.
The SynergEyes VS (Menicon) scleral lens completely vaults the cornea and limbus, landing entirely on the sclera.38 Its toric periphery may be precisely controlled in both the flat and steep meridians, aligning with the scleral for ease of landing and stability.38 This non-rotationally symmetrical lens design incorporates linear landing zones and landing zones with bi-tangential toricity.38 The linear landing zones are designed to follow the linear (rather than curved) shape of the sclera, accommodating a toric sclera.38 This should distribute the lens pressure more equally over the sclera due to the adjustable angles of the flat or steep meridians.38 The company hopes this will improve the scleral lens fit with less risk of air bubble formation or blanching of the conjunctival scleral vessels.38 The toric landing zones can greatly improve vision in patients with residual astigmatism as they are designed to provide consistent
stabilization allowing for a front-surface cylinder.
Table 3. SiHy and Conventional Toric Hydrogel Contact Lenses
|Company||USAN||Brand name||Replacement frequency||Water content||Diameter (mm)||BOZR (mm)||Lens type||Design/Stabilization method/markings|
|Alcon||lotrafilcon B||Air Optix for Astigmatism||1 month DW or up to 6N EW||33%||14.5||8.7||SiHy||Precision balance 8/4 lens design. Markings at 3, 6 and 9 o’clock|
|nelfilcon A||Focus Dailies Toric One-Day ||Daily||69%||14.2||8.6||hydrogel||Back surface tri-curve toric design|
|nelfilcon A||Dailies Aquacomfort Plus Toric (nelfilcon A) One-Day ||Daily||69%||14.4||8.8||hydrogel||Back surface tri-curve toric design|
|Bausch + Lomb||balafilcon A||PureVision Toric||1 month DW or up to 30N CW||36%||14||8.7||SiHy||Prism ballast Lo-Torque Design; Marking at 5, 6 and 7 o’clock; (30 degrees apart)|
|balafilcon A||PureVision2 Toric for Astigmatism||1 month DW or up to 30N CW||36%||14.5||8.9||SiHy||Aspheric optics; Auto Align Design; Marking at 6 o’clock|
|alphafilcon A||Soflens Toric for Astigmatism||1 month||66%||14.5||8.5||hydrogel||Prism ballast; Marking at 5, 6 and 7 o’clock (30 degrees apart)|
|nesofilcon A||Biotrue OneDay for Astigmatism||Daily||78%||14.5||8.4||hydrogel||Peri-ballast (prism free)|
|hilafilcon B||SofLens daily disposables Toric for Astigmatism||Daily||59%||14.2||8.6||hydrogel||Prism ballast; Aspheric design|
|CooperVision||comfilcon A||Biofinity Toric||1 month DW or up to 7N CW||48%||14.5||8.7||SiHy||Optimized ballast design; Marking at 6 o’clock|
|enfilcon A||Avaira Toric ||Two-week||46%||14.5||8.5||SiHy||Optimized ballast design; Marking at 6 o’clock|
|fanfilcon A||Avaira Vitality toric||Two-week||55%||14.5||8.5||SiHy||Optimized Toric Lens Geometry|
|omafilcon A||Proclear Toric||1 month||62%||14.4||8.4, 8.8||hydrogel||Prism ballast; Three lines at 6 o’clock (15 degrees apart)|
|ocufilcon D||Biomedics Toric||1 month||55%||14.5||8.7||hydrogel||Prism Ballast; Marking at 6 o’clock|
|methafilcon A||Frequency 55 Toric/Xcel Toric||1 month||55%||14.4||8.7||hydrogel||Prism ballast|
|somofilcon A||clariti 1 day toric||Daily||56%||14.3||8.6||SiHy||Aspheric|
|Johnson & Johnson Vision||senofilcon A||Acuvue Oasys for astigmatism||2 week DW||38%||14.5||8.6||SiHy||Accelerated Stabilization Design|
|etafilcon A||1-Day Acuvue Moist for Astigmatism||Daily||58%||14.5||8.5||hydrogel||Accelerated Stabilization Design|
|senofilcon A||Acuvue Oasys for Astigmatism with HydraLuxe||Daily||38%||14.3||8.5||SiHy||Accelerated Stabilization Design|
Myopia Control Lenses
Recent research shows a 32% to 42% reduction in myopia using orthokeratology (OK) lenses.39-41 Research also finds partial correction using OK lenses is effective, with high myopes of 6.00D or more partially treated by -4.00D, showing a 76% reduction in myopia progression over one year when compared with spectacle wear.42 Children fitted with a dual-focus multifocal OK lens design in one eye and a conventional OK lens in the fellow eye showed short-term changes to the eye in the multifocal OK lens wearing eyes.43
Concentric and aspheric multifocal designs can slow myopia progression.44 Concentric bifocal lenses, which have a center distance design surrounded by concentric zones of near and distance powers, reduce myopia progression and axial length in children with esophoric fixation disparities, according to investigators.44 Aspheric designs also show reduced myopia progression.45 Use of a center-distance aspheric multifocal design can reduce myopic progression by 50% and axial length by 29% when compared with a single vision wearing group.46
Dual-focus designs and peripheral plus powered aspheric designs also show myopia reduction; however, debate about the visual quality reduction caused by the induction of positive spherical aberration when using this approach persists.47-50
|Fig. 2. This patient displayed epithelial erosion one hour after removing their contact lenses. Photo: Jalaiah Varikooty, MSc, BMed|
Toric Lenses for Astigmatism
A number of new options have recently come to market in this category. In 2017, Bausch + Lomb introduced Biotrue OneDay for Astigmatism daily disposable CLs (nesofilcon A). Initially, these lenses will be available in plano to -4.25D (in 0.25D steps) with cylinder powers of -0.75D and -1.25D and the full range will be available later this year. Johnson & Johnson Vision announced the US launch of Acuvue Oasys 1-Day Brand CLs for Astigmatism. CooperVision announced the limited rollout of Avaira Vitality toric (in the fanfilcon A material). This lens has an optimized ballast toric design and is available in a power range of plano to -6.00D with cylinder options of 0.75D, 1.25D, and 1.75D in axes from 10° to 180° in 10° steps. They have a modulus of 0.6MPa and a Dk/t of 90. Announcements about plus powers, high minus powers and a -2.25 cylinder are expected later in 2017. In June 2016, CooperVision announced the expanded availability of Biofinity XR toric, a monthly SiHy CL. Biofinity XR toric is a cast-molded, made-to-order lens that incorporates the same uniform horizontal thickness and ballast band design as Biofinity toric. The commercially available SiHy and CH toric hydrogel CLs, and the stabilization methods and markings used in their lenses, is available for review (Table 3).
Table 4. SiHy and Conventional Multifocal Hydrogel Contact Lenses
|Company||USAN||Brand name||Replacement frequency||Water content (%)||Diameter (mm)||BOZR (mm)||Lens type|
|Alcon||lotrafilcon B||Air Optix Aqua Multifocal||monthly||33||14.2||8.6||SiHy|
|nelfilcon A||Focus Dailies Progressives||daily||69||13.8||8.6||hydrogel|
|nelfilcon A||Dailies AquaComfort Plus Multifocal||daily||69||14||8.7||hydrogel|
|delefilcon A||Dailies Total1 Multifocal||daily||33||14.1||8.5||SiHy|
|Bausch + Lomb||balafilcon A||PureVision Multi-Focal||monthly||36||14||8.6||SiHy|
|balafilcon A||PureVision2 for Presbyopia||monthly||36||14||8.6||SiHy|
|nesofilcon A||Biotrue OneDay for Presbyopia||daily||78||14.2||8.6||hydrogel|
|samfilcon A||Ultra for Presbyopia||monthly||46||14.2||8.5||SiHy|
|polymacon B||SofLens Multi-Focal||monthly||38||14.5||8.5, 8.8||hydrogel|
|CooperVision||somofilcon A||clariti 1 day multifocal||daily||56||14.1||8.6||SiHy|
|comfilcon A||Biofinity multifocal||monthly||48||14||8.6||SiHy|
|omafilcon A||Proclear Multifocal||monthly||62||14.4||8.7||hydrogel|
|omafilcon A||Proclear 1 day multifocal||daily||60||14.2||8.7||hydrogel|
|Johnson & Johnson Vision||senofilcon A||Acuvue Oasys For Presbyopia||bi-weekly*||38||14.3||8.4||SiHy|
|etafilcon A||1-Day Acuvue Moist Multifocal||daily||58||14.3||8.4||hydrogel|
| *If used in an EW modality, weekly replacement.|
Multifocal lenses have shown improved success in correcting presbyopia when compared with monovision.51-53 Commercially available options are shown in (Table 4).
Last year, PolyVue launched HD Dailies (hioxifilcon, 59% water content), which incorporate an aspheric curvature for each soft lens power and thickness, and compensate for aberrations caused by lens flexure on the eye. Alcon also introduced Dailies Total1 Multifocal CLs (delefilcon A), which uses the same water-gradient technology as the other lenses in the DT1 product line.
The water gradient technology incorporates what the manufacturer calls core and surface optimization: the core material has 33% water content (low water content helps to deliver high oxygen transmissibility) and the surface employs a hydrophilic gel designed to provide lubricity (>80% water). The outer surface has no silicone and is 100% water.
|Fig. 3. Superior epithelial arcuate lesions, as seen here, can result mechanical friction of the lens on the cornea. Mostly seen in those who wear high-modulus silicone hydrogel contact lenses. Click image to enlarge.|
Color CL fits in Asia are quite high when compared with the United States, with about 4% in the United States, and 58% and 41% in Taiwan and Korea.7 Color CLs are mainly used for cosmetic purposes and they also have prosthetic and special effect applications. There are three types of color soft CL that are used to enhance or alter the eye color: transparent tinted lenses, dot matrix computer-generated lenses, and custom hand-painted soft lenses. Lately, the market has seen a huge increase in the sales of limbal ring CLs. Limbal ring CLs magnify the eye appearance and this is achieved by adding pigments to these lenses. These pigments can be located either on the surface or within the bulk of the limbal CL material. Pigment location on seven different daily disposable limbal ring CL materials was studied and, aside from one lens material, all tested lens materials revealed pigments on the surface.54 The pigments located on the surface of the CL will either interact with the palpebral conjunctiva or the cornea depending on location of the surface coating (front or back).
Discomfort associated with CL wear continues to be an issue cannot be attributed to any single factor. Further studies are warranted to understand the impact of these new technologies on CL comfort. Novel CL materials and designs have evolved over the past decade. It would be useful for optometrists to stay up to date on novel innovations in CL materials and designs when prescribing, to avoid or solve a number of common patient problems.
Dr. Srinivasan is an optometrist at the Centre for Contact Lens Research (CCLR), School of Optometry and Vision Science, at the University of Waterloo, Ontario, Canada.
1. Nichols J. Contact lenses 2016 a status quo remains for much of the contact lens industry. Contact Lens Spectrum. 2017;32:22-55.