4.6 How Should a Presbyopic Patient Adapt to His Office Enviroment?
Presbyopia, a result of the gradual decline in accommodation range with age, is the most common refractive error, affecting almost 2 billion people.1
Given the progressive aging of the population, the importance of working in near and intermediate distances across all industrialized societies, it is easy to see the great clinical and social impact of presbyopia.
The new presbyopic patients, still in full working capability and socially active, accept with increasing difficulty the limitations imposed by the natural but inexorable aging process, seeking in the ophthalmologist an easy solution to the problem.
This solution, however, is not always simple and requires a careful evaluation, not only from a clinical point of view but also from a socio-professional level, trying to appreciate the patient's complaints and their relationship with daily activities.
The recent surgical options for presbyopia have brought an added degree of complexity to our clinical decision.
The onset of presbyopia is variable, usually between 40 and 45 years of age.
Depending on factors such as accommodation amplitude, associated refractive error, nature and frequency of near tasks, some complaints of loss of sharpness, asthenia and even occasional headache may be reported with the focusing effort.2
Should we treat all individuals as soon as they start complaining?
For a patient with incipient presbyopia, the appropriate answer depends on specific visual needs.
If you do little work closely or do not feel significant discomfort in these tasks, you probably do not need optical correction.
We should warn our patients about the expected evolution and reassess when necessary, explaining some compensatory strategies to reduce the need for accommodation, such as adjusting the brightness and working distance, as well as adopting more frequent breaks.
In this way we improve some of the symptoms and even delay the first prescription for some months or years after the beginning of the complaints.
In individuals with mild to moderate myopia, it may also be advised to remain uncorrected for longer periods of time, a simple and well accepted solution.2,3,22-23
What strategies to use when prescribing?
Symptoms will generally be more prevalent in prolonged or more demanding close-up tasks.
We should explain to our patient that all types of correction for presbyopia (glasses, contact lenses, or even surgery) always represent some form of compromise when comparing the quality of vision with preserved accommodation.14-22
The use of glasses is undoubtedly the most frequent form of correction.
Patients with constant complaints benefit from optical correction and the minimal addition should be prescribed to allow a clear and comfortable near vision.2-4
We should avoid overcorrection often preferred by patients because despite the improvement of acuity, it will reduce comfort by limiting the field of vision.4
Simple monofocal lenses ("reading glasses") are still an appropriate option for many presbyopes.
The typical candidates are emmetropes or low degree ametropes that feel no need of correction for far, scarcely use of the near addition and prefer a simple and economic solution.
Some contact lens (CL) wearers when well corrected for distance may also prefer this option for closer tasks.
Others, due to previous difficulties in adapting to multifocal lenses, may also favour the monofocal lenses, since they provide a wide field of vision for the intended distance without aberrations.2,5
A possible alternative in the treatment of presbyopia is the use of bifocal lenses, with a more or less evident transition between two fixed dioptric power segments.
The abrupt transition of the image may displease many patients and this option has been falling into disuse by the increasing adhesion to progressive lenses.
Trifocal lenses, on the other hand, incorporate distance, near and intermediate correction, important in advanced presbyopia.2,5
By progressively increasing the power of the lens through a central corridor to the near lower vision zone, progressive lenses can provide good vision at various distances.
The differences between the designs of the lenses are related to the height and width of the corridor of progressive power and, of how much of it is destined to each focal distance.
Different areas of the lens can be expanded, depending on the intended function of the lens and depending on the manufacturer.
However, in addition to the increased cost, there is another "price" to pay since there are peripheral spherical aberrations inherent to the progressive lens design and a narrowing of the area of addition to the central corridor, with potential adaptation difficulties.
Therefore, the quality of vision may be affected in the extreme lateral view, particularly in the lower field of vision.
In everyday life there is usually a wide spectrum of accommodative needs, by inherently varying working distances.12
For some individuals who spend a lot of time at home or in the office, with a predominance of vision close-up and intermediate, traditional progressive lenses do not provide a comfortable field of vision.
A few manufacturers have therefore developed different designs of the lens's dioptric power (so called "office or occupational lenses") that can be tailored to individual needs in near and intermediate vision.
These lenses have a wider intermediate zone for greater computer comfort and close proximity.
This is useful, for example, for those who use the computer but also have to read and interact with people simultaneously in a more confined space.
On the other hand, for more prolonged and constant working distances, monofocal lenses are sometimes the most comfortable solution even for presbyopes who wear progressive lenses.13-15
What advice do you give to facilitate adjustment to correction?
First, in addition to insisting on continued use of the prescribed correction, we should advise patients to increase head movements relative to eye movements.
In this way, they can horizontally move the chin and nose to fixate objects more directly, and vertically adjust the inclination of the eyes and head so that the visual axis intersects the lens in the area with the necessary addition for each task.
We can use everyday examples such as the need to lower our gaze for reading, lower our heads and raise the eyes as we descend stairs, avoid very reclined positions while driving or watching television.
On the computer, in particular, it is advisable to adjust the height of the chair and the screen so that, at a distance of 50-75 cm, the top of the monitor is about 15cm below eye level, in order to maintain a 20 ° inclination when looking at the center of the screen.
This avoids vicious postures resulting from the backward movement and chin elevation when trying to find the spot of greater dioptric power within the lens.
The 20-20-20 rule is a useful mnemonic that reminds us that for every 20 minutes of screen-time we must fixate a distant object (~6meters or 20 feet) for 20 seconds.22-23
In addition to postural corrections and proper lubrication, the focusing ability improves depending on the intensity and quality of the lighting, being maximum with natural light.
The suitability of the ambient light with glare reduction, contributes to increase comfort and accommodative amplitude.
Thus insufficient illumination, dimming very intense surrounding luminosity and the use of anti-reflective lenses may be useful.22,23
Of course, higher ametropias may make it difficult to adapt to progressive lenses, but there are some patients who never get used to dealing with multifocality.
This new sensory reality requires neurological processing and integration (neuroadaptation), a process still poorly characterized and subjected to significant individual variability.
Increased risk of accidents and falls (stairs, sidewalks, etc.) have been reported when compared to the use of monofocal lenses.25
We should therefore be prudent when prescribing in older individuals with impaired mobility or severe ocular comorbidities.
And with contact lenses? What strategies are possible?
Contact lenses are another option when correcting presbyopia but also requires adaptation to its continued use and some compromises in quality of vision.
The number of patients with CL who need correction for presbyopia has increased in recent years, and these are perhaps the most motivated for their continued use.
Associated with prolonged near-work situations using electronic devices, the use of LC exacerbates dry-eye symptoms so the use of lubricating drops may be recommended.22,23
Both rigid CL and hydrophilic lenses can be used to correct presbyopia.24
In this choice, the ophthalmologist should obviously consider refraction but also lens design and ocular physiology, identifying those individuals at greatest risk of CL intolerance.
Other factors such as motivation, comprehension, type of work and non-work related activities, manual dexterity, personal hygiene and financial standing are also important for successful adaptation.24,26
Correction of presbyopia with CL may include monovision and multifocality, by means of alternating vision or simultaneous vision.
Monovision involves adapting one eye with the best correction for distant gaze (usually the dominant eye) and the other for close-up vision.
Although a relatively successful strategy (rates of 60-80%)17,27-30, anisometropia can affect binocular acuity and stereopsis, with potential deterioration in quality of life when comparing to satisfaction with multifocal CL´s , closer to the real needs of everyday life.2,29,31
Factors correlated with better monovision results include good intraocular suppression of blurring, anisometropia less than 2.0-2.5 diopters, good distance correction in the dominant eye, good stereoacuity, absence of endophoria and patient's willingness to adapt to monovision.13,16,17,33
Multifocal (rigid or hydrophilic) lenses are referred to as "alternating vision" or "simultaneous vision" depending on their design.29
Patients may report phantom images, difficulty in scotopic conditions, and reduced contrast.29,32,34
Motivation is also determinant for success, and some individuals are very satisfied, while others tolerate visual performance deficiencies in exchange for the functional and cosmetic benefits of occasional use (social events or sport).2
Finally, another strategy is to combine the use of glasses with monofocal CL´s, as already discussed.
A common example is that of the individual who uses their CL for distance, adding monofocal lenses only for close-up tasks.
Another possibility involves CL´s patients with monovision who use glasses to improve binocular vision in certain distant gaze tasks (for example, driving).2,29
"Doctor, can i have surgery"?
How to answer our patient?
It is not our goal to detail here all the surgical interventions available for presbyopia, their indications and complications.
However, it is increasingly natural for them to be referred by the patient, not reviewing himself in the above-mentioned solutions or who is aware of surgical options through family, friends or online research.
A common and relatively successful form of surgical correction involves the use of monovision, through corneal refractive surgery or through intraocular lens implantation.
A useful strategy may be to pre-test adaptation to monovision with glasses or contact lenses.
Multifocal intraocular lenses have diversified in the quantity and quality of vision that they can offer.
These so-called "premium" lenses, allow variable degrees of multifocality that, as the name implies, produce different images at different focal distances, and it is up to the patient to choose the desired focus on a particular activity.14,35-39
There is always some degree of unpredictability in the process and the risk-benefit ratio of these procedures should be discussed.
Our task is to select the most suitable candidates for each type of lens, not only from an ophthalmological point of view but also from the motivational point of view, to accept the compromise in the quality of vision.
Some patients may complain of glare, halos, and loss of contrast sensitivity, sometimes culminating in explant with lens replacement.40
Individuals with higher visual requirements, who need to drive long periods of time and adapt to constant changes in brightness are not the most suitable candidates.
When in doubt, referral to a refractive surgeon is an appropriate option and may be in the best interest of our patient.
The perfect solution for presbyopia does not yet exist and each option has its advantages and disadvantages.
Comprehensive anamnesis, careful examination, and our clinical opinion are key in adjusting the goals and expectations of our patients, helping them to reach a truly informed decision and realistically adapting to the most appropriate solutions for their needs.