Weng Onn Chan and Jagjit S. Gilhotra
Introduction
The world’s population is rapidly ageing. The National Institute of Aging (WHO) has estimated that the people over 65 in 2050 will be a staggering 1.5 billion; it will represent 16% of the world’s population. In fact, the over 65s will be the fastest-growing segment in society for many countries [1]. In contrast, the current number of over 65 only repre- sents 8% of the world’s population [2]. Most these people will be from the developed world, reflecting the ever improvements in life expectancy. This statistics is sobering considering the major causes of blindness in the developed world are intricately more prevalent in elderly patients; prev- alence of sight-threatening disease drastically increases after 75 years of age [1]. Uncorrected refractive error, cataract, macular degeneration, glaucoma and diabetes are leading causes of visual impairment and blindness in both develop- ing and developed world [3]. Of note, rapidly developing countries like India and China will have disproportionally higher number of new 50+ years old, and unless health poli- cies matches the influx of elderly populations, the number of patients with both avoidable visual impairment and blind- ness will balloon [3].
The Ageing Eye
The eye is an amazing sense organ when one considers the anatomical requirement that results in sight. Light needs to pass through its structures starting from the tear film, the cor- nea, the aqueous, the lens, the vitreous and the retina finally to the photoreceptors. Here light is finally converted into electrical signal that is sent to visual cortex via the optic
nerve which translates this into sight. While this is an overly simplistic overview of the eye, it serves to highlight that if any of the structures are compromised, visual impairment follows. The effect of age on the eye is cruel, and inherently the eye does not age well. From the gradual attrition of fixed number of corneal endothelial cells that are responsible for maintaining corneal clarity to the weakening lens zonules that lead to the loss of accommodation or presbyopia, the compaction of lens fibres is from the moment that we are born to the eventual opacification of the cataract, the wear and tear of the photoreceptors manifesting as age-related macular degeneration and finally the gradual loss of optic nerve’s ganglion cells which can be accelerated in the setting of high intraocular pressure. While normal attrition and degeneration is beyond our current therapeutic intervention (exciting new developments in the field of neurodegenera- tion, stem cells and gene therapy may mean that reversing some of these changes may be possible in the near future) in the following sections, we will attempt to highlight the cur- rent trends in managing these age-related conditions in the elderly population.
The Impact of a Poorly Seeing Ageing Eye The worldwide economic impact of visual loss by the year 2020 has been estimated to be around 3.6 trillion, 2.8 trillion are direct medical cost (e.g. cost of glasses prescription, cost of cataract surgery, cost of intravitreal injections), and around 800 billons are attributed to indirect medical cost (e.g. due to productivity loss, cost of care and loss of inde- pendence) [1, 4]. Rein in a recent analysis of the cost of visual impairment noted that indirect medical cost may be greater and cumulatively may exceed the direct burden of visual impairment [4].
In the following subsections for each disease, we will attempt to highlight the global and personal impact of the individual disease.
W. O. Chan
Southern Australian Institute of Ophthalmology, University of Adelaide, Adelaide, SA, Australia
J. S. Gilhotra (*)
University of Adelaide and The Queen Elizabeth Hospital, Adelaide, SA, Australia
18
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Cataract
Clinically significant cataract is one of the major reversible causes of visual impairment in the oldest old. It accounts for up to 33% and 51% of the worlds rates of visual impairment and blindness [3]. While a very prevalent problem, cataract surgery is also one of the most successful surgeries in the world. Modern cataract surgery has relatively low complica- tion rates and consistently ranks highest in terms of patient satisfaction and quality-of-life improvement following sur- gery. While a highly effective treatment, delay in the delivery of cataract surgery to the needed population is often the rate- limiting step in both the developing and developed world.
The impact of waiting for cataract surgery is significant.
Hodge et al. found in a systemic review that while waiting for cataract surgery, patient’s vision and quality of life con- tinue to deteriorate and the risk of fall increases [5]. Cataract can increase the risk of falls in the oldest old by affecting postural balance, stability and hazard detection [6].
Randomized controlled studies have shown that falls risk is 67% less following expedited (within 4 weeks) first eye surgery when compared to normal waiting time for cataract surgery, but this effect was not observed in second eye sur- gery [7, 8]. Regardless on the rates of falls, the randomized controlled trials all showed the positive effect of cataract sur- gery on both objective and subjective parameters, patients’
activity and confidence increase, and anxiety, depression and handicap levels are lowered compared to the control group [7, 8]. A recent prospective study has shown that in a US population of over 65, the odds of hip fracture within 1 year after cataract surgery were 16% less compared with patients who had not undergone cataract surgery [9]. The odds are further reduced by 23% if the presenting level of cataract was severe [9]. While age related is a bilateral condition, cataract surgery is usually performed one eye at a time.
Meuleners et al. have shown in a population-based study that during this time, patients are at an increased risk of falls compared to prior to having the first eye and after having both eyes done [6]. This may be accounted by the uncor- rected refractive error, the loss of stereopsis and possible increased level of activity following first eye surgery [6]. The implication is clear, patient will need to be warned about the increased risk of falls while awaiting second eye surgery, and all efforts are to minimize refractive difference during this critical period.
Elderly patient undergoing cataract surgery often has sig- nificant systemic and ocular implications. Cataract surgery is increasingly being done under topical anaesthesia which makes systemic co-morbidities less important in the preop- erative considerations for patients having cataract surgery. It is important to note that ocular co-morbidities are common in this age group. Pham et al. have shown that the common- est causes of ocular co-morbidities are age-related macular
degeneration, diabetic retinopathy and glaucoma [10]. These need to be considered fully and are vital to the preoperative counselling for patients. Patients will need to have their expectations adjusted to avoid disappointment. Refractive goal should also be discussed fully. In the oldest old, patients are often content with having different single-vision glasses for distant vision and near vision. This avoids the risk of falls that are associated with bifocal lenses and progressive addi- tion lens. This may happen with image jump associated with bifocal lens and blurring distance objects in the lower visual field (e.g. stairs) with all lens type. In a randomized con- trolled trial, Haran et al. found that provision of single-lens distance glasses to older wearers of multifocal glasses reduces falls by 8%. But in patients with low level of outdoor activity, this significantly increased the risk of fall [11].
Monovision is a state where one eye is rendered emme- tropic and other myopic; the end effect is patient will be glasses-free for both distance and reading vision. This how- ever reduces the stereoacuity for patient. There is paucity of data on the effect of monovision on elderly patients. However, indirectly, reduction in stereoacuity is a known risk factor for falls; as such clinician should err on the side of caution when discussing this option with elderly patients. Another recent addition to the optical correction armamentarium following cataract surgery is multifocal intraocular lenses. As their name implies, these lenses allow the user to see clear at vari- ous focal points. User of earlier reiterations of the lenses was troubled with significant ghosting, glare and haloes that may necessitate reoperation to explant intraocular lens. These symptoms may be particularly prominent in mesopic condi- tions. Again, there is paucity of research in the impact of these newer intraocular lenses on the elderly population and on falls risk. Further prospective studies investigating the effect of these “premium” lenses are required to determine their impact on the oldest old.
Finally, with the advent of femtosecond laser-assisted cataract surgery, patients are finally justified when they ask if their cataract surgery will be done by laser. Patient is often misinformed about traditional cataract surgery that is per- formed with ultrasound probe in most of the developed world or still manually in the developing world. Femtosecond laser is increasingly being used in ophthalmology, and in cataract surgery, it is used to create corneal wounds, create a capsu- lorhexis and fragment the cataract. However, the cataract fragments are still removed using a traditional ultrasound probe. At its current state, laser-assisted cataract surgery per- haps is a more apt description of the procedure. Proponents argue that laser-assisted cataract surgery is better for compli- cated cases and better at preserving corneal endothelium.
However, a recent Cochrane review could not determine the equivalence or superiority of laser-assisted cataract surgery compared to standard manual phacoemulsification [12].
They found similar complication rates, surgical times and
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very similar visual outcomes between the two groups [12].
More importantly, at its current cost, laser-assisted cataract surgery is not cost-effective when compared to traditional cataract surgery [13].
Patients are increasingly being bombarded with “choices”
when it comes to cataract surgery: choice of refractive out- come, choice of intraocular lens and choice of surgery. When approaching an elderly patient, it appears that “simple, tradi- tional cataract extraction with monofocal lens implant” is still the most evidence backed and probably the most appropriate.
Glaucoma
Glaucoma is one of the main causes of irreversible visual loss in the world [3]. It is when the optic nerve is damaged (Fig. 18.1) invariably due to elevated intraocular pressures and presents with typical glaucomatous field defects.
Mechanistically, glaucoma can be divided into open-angle and closed-angle glaucoma. The elderly is more at risk of both forms of glaucoma [14]; open-angle glaucoma is where the drainage pathway is anatomically patent but defective which leads to gradual rise in the intraocular pressure.
Closed-angle glaucoma typically presents acutely when the drainage pathway is obstructed which leads to sudden rise in intraocular pressure. Both forms of glaucoma represent 2%
of global cause of visual impairment and 8% of blindness in
the world population [3]. Additionally, glaucoma also pres- ents a significant health burden to the population due to its chronic nature and lifelong treatment requirement. In the USA alone, the annual direct cost of glaucoma treatment is estimated to be 5.8 billion USD in 2013 [1]. This does not account for the indirect cost including loss of productivity, cost borne by carers and family members. The cost of glau- coma also increases with increasing severity [14].
The burden to individuals is also substantial. Visual loss from glaucoma can negatively affect health-related quality of life even in patients who are unaware they have glaucoma.
There is a linear relationship between the severity of visual loss with the amount of loss in health-related quality of life [14]. Compared to aged-matched individuals, patients with glaucoma are also three times more likely to have falls and six times more likely to be involved in motor vehicle acci- dents and more likely to be at fault in the collision in the preceding year [15].
Regardless of mechanism, there is only one effectively known treatment which is lowering of intraocular pressure.
As the change with glaucoma is often insidious, compliance to medication can be a major issue. Gurwitz et al. have previ- ously shown that in the elderly population, there can be up to 23% non-compliance following initiation of therapy, and patients can go without therapy for up to 112 days during the first year of treatment. They also found that medications requiring more than twice daily use and presence of concur- rent medications are risk factors for non-compliance [16].
Simple once a night dosing of prostaglandin analogue has been shown to result in better compliance for adherence [17].
While we know that lowering intraocular pressures slows progression of glaucoma progression, the effect of non- compliance on glaucoma progression is less well defined. In a meta-analysis of the literature, Waterman et al. found that education and personalized interventions can lead to better adherence in ocular hypotensive therapy, but the effect on intraocular pressures and visual field progression is unclear.
They also found weak evidence that simplifying drug regime also improves treatment adherence [18].
When compared to recent advancement in cataract sur- gery, treatment for diabetes and age-related macular degen- eration and the treatment for glaucoma remain relatively similar. The traditional stepwise algorithm of medical, laser and drainage surgery still holds for glaucoma. More recently, the use of minimally invasive glaucoma surgery is increas- ing. The main impetus is to provide a glaucoma treatment that is minimally invasive and effective, has high safety pro- file and provides rapid recovery [19]. The role of this surgery is to provide an intermediate management for patient that requires “something more” before committing them to full glaucoma surgery that can be associated with significant morbidities. In a recent meta-analysis, Lavia et al. concluded that while before and after studies showed that MIGS are
Fig. 18.1 A red-free fundus image of a glaucomatous disc. There is increase cup to disc ratio with thinning of the neural retinal rim which is characteristic of glaucomatous optic neuropathy
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effective in lowering intra ocular pressures and number of glaucoma medications, these results were derived from non- comparative studies. However, there were limited evidence found when looking at trials that directly compare MIGS to medical therapy [20].
Age-Related Macular Degeneration
The oldest old is especially susceptible to age-related mac- ular degeneration; while only 2% of under 50s will be affected by ARMD, this rises to over 35% for over 85s [1].
ARMD is multifactorial, and both environmental and genetics factors have been elucidated recent. Of particular importance is the genome-wide association studies that were identified to be involved in the complement pathway being associated with increased risk of developing wet macular degeneration.
While the majority of patients suffering from macular degeneration have the “dry” or non-exudative form (Fig. 18.2) which are characterized by slow and gradual loss of vision, 10–20% of patients can progress into the exudative or “wet” ARMD that leads to sudden and often severe loss of central vision if left untreated (Figs. 18.3 and 18.4) [21].
Since the landmark study of ANCHOR [22] and MARINA [23], the use of anti-vascular endothelial growth factors has taken off. What was once considered an irreversible loss of vision from wet ARMD is now treatable; ophthalmologists are now able to regain vision loss by regular injections of anti-VEGF agent. This was a dramatic shift in treatment par- adigm when considering prior to anti-VEGF; the dictum of exchanging a large scotoma with a smaller scotoma was the standard of care with thermal laser and photodynamic ther- apy. All the initial trials on anti-VEGF showed that with intensive treatment, visual gain of more than two Snellen lines can be achieved in ~30–40% of patients and upwards of 90% of patients will maintain their pretreatment visual acu- ity, and less than 5% will be resistant or not responsive to initial treatment [22, 23].
However, with longer-term real-world data of unselected group of patients in routine clinical practice, we now know that if patients are commenced on treat-and-extend proto- cols, the number of injections and clinic visits is significantly less when compared to original trial protocols of monthly injections while achieving similar success rates. Even with the reduced treatment visits, the average number of injec- tions during the first 2 years is around 13 injections.
Fortunately, patients can be reassured that eventually more
Fig. 18.2 End-stage “dry” or non-exudative macular degeneration. The macula is atrophic and subjectively the patient would have very poor central vision but preserved peripheral vision
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than 50% of patients can stay in disease remission with 8 weekly or less injections [24].
While these data are impressive, the treatment burden on patients and clinicians to maintain trial-like conditions is enormous. Both direct cost to the patient and indirect cost for caregiver services for ARMD are substantial and propor- tional to the disease progression [25]. It is estimated that in UK, the annual cost for treating wet ARMD is 860 million, and in India, the annual cost for anti-VEGF drug alone is 1.2 billion [26]. This cost is prohibitively expensive for develop- ing countries and will only continue to rise as the world ages and maintenance anti-VEGF therapy tends to be life-long.
Not only the economic cost to patients and society, overall quality of life and independence are affected in parallel with worsening visual loss [25]. Having to relinquish valued activities due to worsening visual acuity from macular degeneration has been associated with increased risk of cog- nitive decline [27]. Time commitment for staff and patient is also significant, with ARMD patients accounting for up to 20% of healthcare staff’s time per week and up to 90 h of patient and caregivers time per visit [25].
In the elderly patients, frank communication about the treatment frequency and duration of treatment is vital. Unless clearly communicated, most patients do not understand that
Fig. 18.3 Colour fundus image of right wet age-related macular degeneration.
Pigmentary changes and drusens are hallmarks of age-related macular degeneration
Fig. 18.4 Corresponding optical coherence tomography showing cross section of the macula. The hyporeflective cystic spaces are exuda- tive changes from wet age-related macular degeneration. The rippled layers under the cystic spaces are drusens. Anti-VEGF treatment has revolutionized the management of this condition
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anti-VEGF treatment is life-long and cessation of treatment can lead to reactivation of wet CNVM [24]. Equally impor- tant is for clinicians to stress compliance on measures to detecting and reducing risk of wet CNVM in the other eye with Amsler grid monitoring, AREDS2 formulation and stop smoking. AREDS formulation for ARMD is the only shown preventative measures that reduce the risk of ARMD pro- gression by 25–30% by 5 years [28]. Importantly, compli- ance of these lifestyle modifications is often poor, and often repeated multidisciplinary reminders are required given that ARMD is bilateral in up to 40% of patients [21].
While the vogue over the last 15 years has been on wet ARMD, there are increasing foci on dry macular degenera- tion. GA accounts for 85–95% of ARMD patients up to 20%
of blindness due to macular degeneration [29]. While there is currently effective treatment for wet ARMD, the only evidence- based intervention in dry ARMD is AREDS sup- plementation [28]. Currently trials are underway to evaluate the role of anti-inflammatory, anti-oxidative, lipofuscin and visual cycle inhibitors, choroidal blood flow modulators and stem cell therapy on drusen load and geographic atrophy [30]. Surgically, implantable telescopes seem to be effective in improving vision but at its current state are complicated with significant rates of persistent inflammation and explan- tation [30].
It is not infrequent that patients with end-stage macular degeneration will enquire about the role of bionic eye in the treatment of ARMD. While there are no published results, retinal implants have been implanted in patients with macu- lar degeneration with promising reported outcomes. In a series of five patients, Stanga et al. reported that patients reported no confusion between normal peripheral vision and the artificial phosphene vision; more importantly patient reported improved visual acuity up to BCVA of 1/40 and ability to recognize facial features [31].
Currently, we have a respectable armamentarium of treat- ment options for patients suffering from ARMD, and new research in this field is promising. However, at its current state, ARMD remains one of the major causes for visual impairment in the elderly and treatment while effective, exacts a significant treatment burden to patient and society.
Visual Aids and Practical Tips for the Elderly Practical Advices
When dealing with visual loss in the oldest old, the clinicians play an extremely important role as the primary health advo- cate for the patients. Often patients and family members are unaware of services available to help make visual loss more manageable. Unfortunately, even conditions such as ARMD are often misunderstood and often receive with similar dread to a “blind” sentence. A simple reassurance to the patients
that they will never go “lights-out” blind but will always retain navigational vision but with a “blurry central blob” is enough to help them through the initial shock of dealing such diagnosis. Similarly, aligning patient’s expectation and help- ing them understand treatment goal in glaucoma help signifi- cantly with compliance. Often patients may lapse in compliance as the “drops are not helping me see any better”
or “I don’t notice any difference”, explaining that “no change is good news” and drops should never be stopped is essential in ensuring treatment continuation. From a multidisciplinary viewpoint, ensuring patient has not lapsed in follow-up for chronic conditions such as glaucoma and diabetic retinopa- thy is equally important.
Friendly Services
Even ophthalmology clinics are often ill equipped from time and equipment perspectives when dealing with patients with severe visual loss. Developing a working relationship with allied health services such as local low vision society and occupational therapist can ensure a smooth transition of care for patients. Low vision centre plays a critical role in coordinating various services for such patients, from intro- ducing appropriate visual aids or adaptive technologies to implementing home modifications, providing print alterna- tive, coordinating social services and improving lighting conditions for patients. The importance of these cannot be overstated in helping patients with low vision maintain independence. Adaptive technology has improved dramati- cally in the age of smart phones and tablets. Electronic mag- nification is easily achieved and apps specially designed for low visions are abound to help with magnification, contrast and voice command for the low vision user. Optical charac- ter recognition has improved significantly and allows patients with severe visual loss to again enjoy reading mate- rials through audio. The low vision centres are invaluable in assessing which of these options are suitable for the indi- vidual and helping the patients get accustom to the new technologies. While these technologies are comparatively cheaper than before, the initial investment into such tech- nologies can be prohibitively expensive for pensioners.
Low- vision centres often provide short-term loan or trial units coupled with training for patients before they commit to certain products. Finally, from a practical viewpoint, often there is a misconception and even reluctance from a patient’s perspective in being referred to low-vision centres.
Attending such services is often viewed as resignation to giving in to low vision. The clinician plays an important role in encouraging patients in attending such services as build- ing up an early therapeutic alliance and implementing some of the aforementioned services when patient still has rela- tively good vision which can help patients adapt better to them.
W. O. Chan and J. S. Gilhotra