In Part 1 of this 2-part article, we took a look at the prevalence and impact of digital device use. Part 2 below discusses the clinical performance of Biofinity Energys®.
Biofinity Energys®: Tackling lens discomfort and ocular tiredness with technology
Biofinity Energys® is part of the Biofinity® family of contact lenses (Table 1). Demonstrating CooperVision’s commitment to continuous innovation, the Biofinity® family is a widely prescribed reusable lens globally. This is, in part, thanks to its wide prescription range, providing correction for 99.7% of prescriptions.31
As outlined above, maintaining comfortable lens wear in digital device users is crucial. Aquaform® Technology used in the comfilcon A material and common to all Biofinity® lenses, allows for naturally wettable silicone hydrogel materials without the need for surface treatment. In the matrix of long silicone chains, hydrogen bonds form to lock water molecules within the lens, for inherent wettability and a comfortable lens-wearing experience. This allows the lens to attract and retain moisture. The long chains mean that less silicone is needed, resulting in a material with balanced properties of water content (48%), modulus (0.75 MPa), and oxygen transmissibility (for sphere: Dk/t 160 x 10-9 @ -3.00D).
In addition to the comfort benefits of the Biofinity® family, Biofinity Energys® lenses feature the Digital Zone Optics® lens design, which helps with eye tiredness caused by focusing on digital devices (Figure 1). Multiple front-surface aspheric curves distribute power evenly to simulate positive power across the entire optic zone, so wearers can change focus from on-screen to off-screen and back with less effort. This eases accommodative burden and may help reduce ciliary stress.32,** Distance vision is not adversely impacted by the unique Digital Zone Optics® design and fitting Biofinity Energys® in practice is no different to fitting a standard, spherical, single vision, soft lens. *
Clinical performance of Biofinity Energys®
- Close focusing stress in current contact lens wearers
Viewing digital devices requires long periods of close focusing, which, in turn, requires sustained contraction of the ciliary muscle. This effort contributes to the symptoms of ocular tiredness, termed ‘asthenopia’, as described above. Accommodative micro-fluctuations result from spasm of the ciliary muscle when viewing a near target, and manifest as tremors or a state of temporal ocular instability,33 and are measured as changes in the refractive power of the eye over time.
So can the simple act of wearing a contact lens designed to alleviate eye tiredness associated with close focusing make a measurable difference to the amount of stress the ciliary muscle is subjected to? This was investigated in a recent study. Accommodative micro-fluctuations were measured for a standardized close reading task on an iPhone using controlled screen brightness and ambient lighting conditions. Sixty-eight adapted lens wearers completed twenty minutes of reading at a 25 cm viewing distance, using both a standard spherical contact lens (Biofinity®) and the Digital Zone Optics® design (Biofinity Energys®).32
The change in accommodative micro-fluctuations from before to after the reading task was statistically lower for Biofinity Energys® compared to the standard spherical lens (Figure 2). This suggests Biofinity Energys® reduced ciliary muscle stress for the reading task set in the study, and that the novel Digital Zone Optics® design may be useful for digital device users who are experiencing eye strain.32**
- The ocular benefits of fitting neophytes with Biofinity Energys®
Is Biofinity Energys® a suitable option for neophytes? If comfortable use of digital devices is potentially more challenging for lens wearers, how does this technology compare to staying in spectacles? Are there benefits patients receive by
switching to contact lenses? Sixty-one spectacle wearers who regularly used digital devices were eligible for inclusion in a study to investigate these questions.34 Thirty two were fit with Biofinity Energys®, and twenty nine continued over the two month study period with their up to date single vision spectacles. The impact of wearing contact lenses on quality of life was quantified using a validated questionnaire,35 and symptoms of computer vision syndrome were also assessed.
Quality of life scores increased over the two-month period for the contact lens wearing group, driven mainly by improved performance for outdoor, fitness activities and use of non-prescription sunglasses. The spectacle group reported similar, unchanged, quality of life scores between baseline and two months. At two months, the difference in scores between the two groups was judged to be both statistically significantly different and clinically meaningful. The lens wearing group reported significant and positive responses towards contact lenses suggesting they were highly satisfied with their correction.34 In fact, the clinical performance and visual acuity of Biofinity Energys® was comparable to single vision spectacles34, demonstrating how well neophytes adapted to a monthly replacement contact lens. There were no differences in symptoms of computer vision syndrome questionnaire results between groups. These are useful results to bear in mind when considering whether to recommend contact lenses to patients for the first time.
Tips for Eye Care Professionals
- Using Biofinity Energys®
Based on the available evidence, Biofinity Energys® is suitable both for patients new to contact lenses, and for existing wearers who may be experiencing suboptimal visual comfort with their current lenses when using digital devices. In practice, ECPs can question their patients on their use of digital devices, in order to gain an understanding of the range of screens used and the time spent per day viewing them. It should be remembered that the patient may not volunteer their experience when using devices, perhaps believing that some degree of ocular discomfort is inevitable. This makes it extremely important to be proactive and enquire about their ocular comfort when viewing computers, tablets and smartphones.
When recommending Biofinity Energys®, communicate its features to patients: the combination of a widely used silicone hydrogel lens material with a unique optical design to help alleviate the symptoms of tiredness that can occur with prolonged digital device use. If feasible, enabling the patient to experience the lenses while using their usual devices may be useful for them to experience the visual benefit of the Digital Zone Optics®.
It is always important to provide good education on the safe wear and care of contact lenses. New wearers should be supported with time to practice handling techniques and given access to information for their use at home to help remember the steps in their daily wear and care routine. Manufacturers often have information for patients available on their websites; an example from CooperVision is available here. Contact lens aftercare provides a regular opportunity to check the habits of existing wearers and correct any bad habits that have crept in. Practicing compliant lens wear not only minimizes the chances of an adverse event such as microbial keratitis36,37 or corneal infiltrative events,38 but also helps to maximize comfortable wear time36. Contact lens wear continues to be an effective option for vision correction millions of wearers around the world, with a recent review finding no evidence of increased risk of contracting COVID-19 through lens wear.
Helping to alleviate digital eye strain in all patients
Beyond specific contact lens-related advice, there are a number of other tips ECPs can share with patients to help them manage any eye strain they may be experiencing (Table 2). Remember the nature of digital eye strain is often multifactorial, which results in an holistic approach being recommended to help address the condition.1 Strategies to relieve, or better still, to prevent, digital eye strain have been covered in a number of reviews.1-3 The ergonomic set up when using digital devices should be considered, and this necessarily varies depending on the type of device being used. Incorrect set up or poor posture can result in back, shoulder and neck strain.7,43 Ambient light should be set to a comfortable level, and screen luminance, text size, resolution and contrast adjusted to feel optimal for the user. It can feel more comfortable to minimize any reflections falling on the screen, however evidence for the use of anti-glare filters remaining equivocal.1 Refocusing on far objects has been found to be more effective than taking breaks from viewing devices alone.44 The 20-20-20 rule is widely shared in the literature, which encompasses taking a twenty second break every twenty minutes to view something at least twenty feet away. Although it has been pointed out that this ‘rule’ has not been validated or the subject of peer review,45 it does form common sense advice to help relax accommodation and vergence to limit the amount of asthenopia experienced.
Ocular factors to address in cases of digital eye strain include ensuring the refraction is up to date, that any presbyopia is appropriately corrected, and in soft contact lenses, any astigmatism of 0.75DC or more is corrected.46,47 ‘Occupational’ varifocals or prescriptions specific to device viewing distances may be helpful. The use of spectral filters, such as blue light filters, is growing in popularity, however a recent systematic review suggested more research is required to confirm their efficacy.48 Oculomotor balance should be assessed, addressing any accommodative or vergence issues present. Take care to assess convergence and how well compensated any exophoria is in myopes newly fit with contact lenses; they lose the effect of base in help in their spectacles when wearing their contact lenses.
Underlying dry eye conditions such as suboptimal tear film quality or quantity should be investigated and managed. The combination of altered blink rate, increased number of incomplete blinks.16,19 and time spent in air conditioned environments all add to the chance of ocular surface dryness. The integrity of the ocular surface should be carefully checked with diagnostic dyes such as fluorescein, and any aqueous or evaporative tear film issues present managed. Symptomatic screen users may also benefit from using artificial tears. Increasing humidity in dry environments can help to improve ocular comfort.49 Blinking exercises can be prescribed, or on-screen blinking prompts may be used, however both strategies have limited effect in reducing eye strain.1,50 Remember too that contact lens wearers are at increased risk of ocular discomfort and eye strain,21,23,51 and beyond considerations of accurate correction of refraction, and appropriate lens material, replacement schedule and care system, the use of suitable lubricating drops may also be beneficial in this group.52
Rather than asking patients if they use digital devices, perhaps the more useful route in today’s world is to ask how many types of screens they use regularly and for how long each day. Do not let patients assume eye strain and fatigue are expected side effects of sustained screen viewing. Proactive questioning and appropriate refractive and ocular surface assessment will help elicit issues, providing greater opportunity for the ECP to intervene with advice and management strategies.
Wearing a contact lens for these tasks adds an additional challenge to the tear film and increases the chance of ocular discomfort and fatigue. Results shared here illustrate that beyond general advice for the management of digital eye strain, relief from accommodative stress is possible via use of a lens designed to help alleviate ocular tiredness.** Biofinity Energys® has been designed to meet the visual demands of patients’ modern lifestyles and may benefit both existing and new contact lens wearers who routinely use digital devices.
*CVI Data on file 2016. Prospective, multi-center, subject-masked, bilateral, one month dispensing study in USA with Biofinity Energys in existing Biofinity sphere wearers. N=52. At dispensing and after one month of wear.
** Based on a statistically significant difference of the mean change in Accommodative Microfluctuations and when compared to Biofinity sphere after reading on an iPhone for 20 minutes.
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