Published in Cataract

The Prevalence of Cataract Blindness and the Life-Saving Impact of Cataract Surgery

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10 min read
Explore some of the most alarming facts about cataracts in relation to overall health as well as the most commonly reported benefits of cataract extraction.
The Prevalence of Cataract Blindness and the Life-Saving Impact of Cataract Surgery
Near or distance vision impairment impacts at least 2.2 billion people on the planet.1 Equally as shocking, at least one billion of these same cases of vision impairment could have been prevented or could still be tackled.1 Cataracts, loss of lens transparency due to opacification of the lens, are one cause of preventable visual impairment which affect approximately 95 million people worldwide.1
Many people have heard of the term “cataracts” before, but fewer know the health risks associated with them. When broaching the subject of cataract surgery with a patient, it is crucial to relay both the commonality and preventability of cataracts, among other key benefits that patients would want to know when contemplating intervention for this diagnosis.
There are many different reasons why cataracts can occur, but age-related cataract is the most common type in the adult population, with an onset in those between the ages of 45 and 50. Some studies have even reported that the prevalence of cataracts increases with age, from 3-9% in ages 55-64 years to as much as 92-96% in those 80 years and older.2 The burden of cataract is predicted to increase dramatically over the next decades, especially in Western countries, because of longer life expectancies and progressive aging of the population.2
This article will explore some of the most commonly reported benefits of cataract extraction as well as offer a sample script in discussing the benefits.

Cataracts as a predictor for earlier death

As common as cataracts are, they have also been associated with serious health conditions. The Blue Mountains Eye Study, a population-based cohort conducted in Australia in 2007, assessed the longer term (11-year) mortality risk associated with visual impairment and its two principal causes: age-related macular degeneration and cataract.1 It concluded that any cataract, with cortical, nuclear, and posterior subcapsular cataracts considered separately, was a significant predictor of all-cause mortality in the overall population.3
This can be explained to a patient as cataracts having been associated with mortality of all causes—not to say that cataracts lead to earlier death, but they have been found to be related with mortality overall.
Additionally, any cataract was shown to significantly predict vascular mortality (from conditions such as diabetes mellitus, hypertension, angina, acute myocardial infarction, and stroke) in all persons 49 years and older, even following consideration of visual impairment and other potential economic and biological confounders.3 It was still unclear whether visual impairment, age-related eye disease, or both are markers of aging and frailty or whether these ocular conditions accelerate aging, thus leading to earlier death in older persons.
What was certain was that the association between visual impairment and all-cause mortality is mainly observed in persons younger than 75 years at baseline in the initial analysis and that in the older group, it is likely that other age-related conditions dominate the effect on mortality.3

The link between cataracts and dementia

Another crucial point to communicate to patients and their caretakers would be the link between cataracts and dementia, as recently they have been shown to increase the risk of dementia. Kuzma et. al (2021) found that visual impairment based on visual acuity was associated with incident all-cause dementia, Alzheimer’s disease and vascular dementia.1,4
It was also acknowledged in this study that visual impairment often co-occurs with hearing impairment, another form of sensory deprivation which has recently been highlighted as a potential modifiable risk factor for dementia.
Both sensory impairments may share common pathways and the risk of dementia might be greater in the presence of both vision and hearing impairment.4 Lee et al. (2022) examined participants over the age of 65 undergoing cataract extraction to assess whether they had a lower risk of developing dementia than those who did not undergo surgery.1,5 They found that the risk of developing all-cause dementia in participants who underwent cataract extraction was significantly lower than that for people who did not undergo cataract surgery.
These findings were explained by the relationship between sensory impairment and cognitive decline. Sensory impairment may contribute to social isolation and decreased cognitive stimulation, which may increase the risk of dementia. It was also acknowledged that prior studies on the associations between cataract extraction and dementia development have been conflicting; this is thought to be due to disparities in dementia identification parameters used in these studies.

The connection between cataracts and falls

Cataract surgery has additionally been shown to reduce the rates of falls. In a study examining rates of falls with cataract surgery, surgery for the first eye was found to reduce the rate of falls by 34% but not the number of “fallers.”1 However, surgery for the second eye in people with cataract did not reduce the fall rate.
In another community based study, poor visual acuity, reduced contrast sensitivity, and decreased visual field were found to be risk factors for reporting two or more falls in the previous 12 months.1
In addition, presence of a posterior subcapsular cataract and use of non-miotic glaucoma medication were also associated with two or more falls. A study by Brannan et al. (2003) demonstrated a significant reduction in the risk of falls after cataract surgery, and suggested that elderly patients—those using more than four medications per day and those who have had a preoperative fall—are most likely to benefit from a cataract operation, in terms of reducing the risk of a fall.6 Patients using a mobility appliance are still at risk postoperatively.1

Cataract surgery and quality of life

A final benefit to cataract surgery is its exceptional impact on quality of life, thus affecting mental health. Studies have suggested that cataract surgery may improve cognitive function and reduce depressive and neuropsychiatric symptoms.1 Pellegrini et al. (2020), found there was found to be a significant association between postoperative improvement in depression and the baseline visual acuity.
Figure 1 simulates blurry vision related to cataract and clear vision after successful surgery.
https://covalentcareers3.s3.amazonaws.com/media/original_images/LilyCats_2_XWhsF5t.jpg
Figure 1: Contributed by Alanna Nattis, MD.
Previous studies demonstrated that patients awaiting cataract surgery with worse visual acuity are more likely to be depressed.1,2 Even functional and structural brain changes have been shown to be reversed following cataract surgery, with improvement of grey matter volume and fractional amplitude of low-frequency fluctuations in vision and cognition-related areas.1

Sample script for cataract discussion

Care Provider: Your examination has shown that you have cataracts. What do you know about cataracts?
Patient: I’m not sure what they are exactly, but I know they lower your vision. I think my parents had them before they died, but they never did any surgeries.
Care Provider: It’s true that they do decrease your vision. Would it be ok if I tell you more about what cataracts are and why they occur?
Patient: Yes, please.
Care Provider: Cataracts are when your lens, a normally clear disk which helps focus light onto the back of your eye, becomes cloudy. This is a process that usually happens with age, starting when you are between 45 and 50, as proteins in the lens break down and make things less clear.
Patient: Oh, that makes sense why I can’t see as clear as I used to. I knew I should have worn my glasses more.
Care Provider: Well, cataracts affect most people and are a natural process of aging.
Patient: Oh I see. I don’t want to get surgery though.
Care Provider: Surgery is an individualized decision that everyone should agree to with full confidence. Not all patients with cataracts are ready for surgery. Could I tell you more about why we do recommend patients to remove cataracts?
Patient: Yes.
Care Provider: Besides the obvious benefit of being able to see clearer in the vast majority of cases, cataracts have been associated with a higher risk of dementia, falls and depressive symptoms. What this means is that a great loss of vision usually ends up affecting multiple aspects of your life, including your health and livelihood. I know you have mentioned in the past that you have had a few falls recently.
Patient: Yes, it was very scary. I haven’t been able to see as well as I used to.
Care Provider: It is possible that your cataracts may have contributed to those recent events. Considering these falls as a health risk to you, I would highly recommend cataract surgery to improve not only your current quality of life but avoid any falls, which could lead to greater health risks down the line. I know you mentioned not wanting to do surgery, and I would like to hear your reasoning.

Final thoughts

In conclusion, there are many benefits to cataract surgery which include improving quality of life and reducing the rates of falls (and therefore significant morbidity). While every surgery has risks, cataract surgery should be considered as a vital option in those who have developed visually significant cataracts.
When discussing cataracts with patients, it is vital to glean the patient’s understanding in addition to educating with permission and tailored responses to the patient’s individual situation and lifestyle.

References

  1. Vision Loss Expert Group of the Global Burden of Disease Study. Causes of blindness and vision impairment in 2020 and trends over 30 years: evaluating the prevalence of avoidable blindness in relation to “VISION 2020: the Right to Sight”. Lancet Global Health 2020. doi.org/10.1016/S2214-109X(20)30489-7
  2. Liu YC, Wilkins M, Kim T, et al. Cataracts. Lancet 2017; 390: 600-12.
  3. Cugati S, Cumming RG, Smith W. Visual Impairmenet, Age-Related Macular Degeneration, Cataract, and Long-term Mortality: The Blue Mountains Eye Study. Arch Ophthalmol. 2007;125(7):917-924. doi:10.1001/archopht.125.7.917
  4. Kuzma E, Littlejohns TJ, Khawaja AP, et al. Visual Impairment, Eye Diseases, and Dementia Risk: A Systematic Review and Meta-Analysis. Journal of Alzheimer’s Disease 83 (2021) 1073–1087.
  5. Lee CS, Gibbons LE, Lee AY, et al. Association Between Cataract Extraction and Development of Dementia. JAMA Intern Med. 2022 Feb; 182(2): 134–141.
  6. Brannan S, Dewar C, Sen J, et al. A prospective study of the rate of falls before and after cataract surgery. Br J Ophthalmol. 2003 May; 87(5): 560–562.
  7. Foss, AJ, Harwood, RH, Osborn, F. Falls and health status in elderly women following second eye cataract surgery: a randomised controlled trial. Age Ageing 2006;35:66–71.
  8. Ivers RQ, Cumming RG, Mitchell P, et al. Visual impairment and falls in older adults: The Blue Mountains Eye Study. J Am Geriatr Soc 1998;46:58–64.)
  9. Maharani A, Dawes P, Nazroo J, et al. Cataract surgery and age-related cognitive decline: A 13-year follow-up of the English Longitudinal Study of Ageing. PLoS One. 2018; 13(10): e0204833.
  10. Freeman EE, Gresset J, Djafari F, et al. Cataract-related vision loss and depression in a cohort of patients awaiting cataract surgery. Can J Ophthalmol. 2009;44:171-176.
  11. Palagyi A, Rogers K, Meuleners L, et al. Depressive symptomsin older adults awaiting cataract surgery.Clin ExperimentOphthalmol. 2016;44:789-796.
  12. Lin H, Zhang L, Lin D, et al. Visual restoration after cataractsurgery promotes functional and structural brain recovery.EBioMedicine. 2018;30:52-61.
Vasiliki Gliagias
About Vasiliki Gliagias

Vasiliki Gliagias is an incoming intern at Northwell Health and an aspiring ophthalmologist. She worked as an ophthalmic technician prior to starting medical school and dedicated a year to studying early glaucoma for research pursuits at Manhattan Eye, Ear and Throat Hospital. Vasiliki enjoys drawing, yoga, spending time with her friends and family, and outdoor activities in her spare time.

Vasiliki Gliagias
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