As the general population ages, the incidence of cataract and surgical volume will steadily increase. This will create an increased demand for optometric comanagement in identifying cataract patients and determining which ones require surgery.
The O.D.s role is critical in determining the level of visual disability the patient suffers. Specifically, we provide a clinical evaluation of severity and educate the patient on his or her alternatives.
In conjunction with the cataract surgeon, we are also responsible for providing our patients with rapid access to care, recognizing when patients require surgery and maximizing their visual outcomes following surgery.
This article, the sixth and final in our series, Back to the Basics, reviews cataract development, diagnostic testing and patient care, and introduces several preoperative comanagement strategies.
Cataracts 101
Our role in the preoperative management of cataract patients begins with education. We must be aware of demographics, incidence and prevalence models, and know how they apply to each patient. Also, some forms of cataract are preventable, which requires education on comanagement of medical conditions with internists and specialists. An extensive knowledge of proper nutrition and overall systemic wellness is also helpful.
Cataracts affect approximately 20.5 million Americans past age 40, with an expected increase to 29 million Americans by 2020.1,2 As noted in the Beaver Dam Eye Study, the incidence of nuclear sclerotic cataracts increases dramatically after age 64, with a high progression rate.1 This is followed by the development of cortical and posterior subcapsular forms of lens opacities.1 The incidence and progression rate also change based on other issues, such as diabetes, trauma, toxin exposure and other environmental influences.
Risk Factors for Cataracts
The risk factors for the development and progression of cataracts include:
Age. Advanced age is the primary risk factor for cataracts.
Exposure to oxygen free radicals (oxidants). Exposure to chemical toxins, cigarette smoke or infections can be a significant risk factor for cataracts.2,3
Radiation and electromagnetic waves from sunlight and ultraviolet (UV) exposure. UV exposure is a major risk factor for cataract development and progression. Sunlight exemplifies destructive properties that can cause cataracts by promoting oxidation and degradation of lens proteins.4
The lens naturally absorbs UV radiation and protects the internal ocular structures, but there is a limit of how much radiation it can absorb. Long-term exposure even to low levels of UV-B radiation can eventually cause lens changes, which contribute to cataract development.
This is documented in one study of 838 watermen who worked on the
The results suggest an association between UV-B radiation and cataract formation, and supports the need for ocular protection from UV-B.6
Medications. Various systemic medications, especially corticosteroids, can induce cataracts. Long-term use of oral steroids is a well-known cause of cataracts. The incidence with low-dose (10mg/day) corticosteroids is approximately 21% to 36%.7,8
Studies conflict, however, as to whether inhaled and nasal-spray steroids increase the risk for cataracts. Information on cataract risk from inhaled steroids is important because asthma patients commonly use them. Also, allergy sufferers increasingly use steroid sprays. There may be a higher risk for cataracts among middle-aged and elderly patients treated with Vanceril (beclomethasone, Schering-Plough) or Beclovent (beclomethasone, GlaxoSmithKline).8 Cataract development in children is rare, and the benefits of inhaled steroids for asthma far outweigh any small associated risk.
Smoking. Cigarette smoke introduces oxidants to ocular tissues. Secondhand smoke exposure decreases zinc concentration in the lens. Zinc is a natural antioxidant that plays a vital role in maintaining lenticular transparency and preventing lipid peroxidation.9
The Blue Mountain Eye Study found that individuals who ever smoked cigarettes have a higher prevalence of more severe nuclear and posterior subcapsular cataracts than nonsmokers. The accumulation of copper, lead and cadmium in the lens due to nicotine breakdown is associated with the hastening of cataractogenesis.8
Alcohol. In one study, individuals who consumed a minimal to moderate volume of alcohol (less than one drink a day) demonstrated a lower prevalence of cortical cataracts vs. people who did not drink at all.10-12 However, heavy alcohol consumption (four or more drinks a day) was associated with a higher incidence of nuclear cataracts. Excessive alcohol use often induces posterior subcapsular cataract changes, which are similar to cataracts associated with dehydration and pathological diarrhea.13
60+ Generalized, symmetric or asymmetric reduction in appreciable vision and acuity. Loss of color appreciation for blue/yellow. Monocular diplopia. Increased glare (light scatter). Monocular diplopia. Decreased visual acuity. Near vision is better than distance vision due to visual axis impingement.
Subjective Findings and Age Expectations of Cataract Development
Type of Cataract
Approximate Age of Onset
Subjective Symptoms
Nuclear sclerotic
Myopic shift (rule out diabetes).
Cortical
50+
Increased glare (light scatter).
Posterior subcapsular
40+
To determine the subjective effect of cataracts on visual function and quality of life, start with a thorough history. Also, address the patients medical concerns, explain his or her treatment and/or alternative care options, and administer a visual function survey or questionnaire. Any problems determined in the history will ultimately reveal the etiology of the cataract, suitability and prognosis of a surgical procedure.
Note all medications the patient is taking. He or she may not be aware of a specific drugs ocular side effects. Some medications, such as ibuprofen, may cause cataracts to form or progress. (See Identify the Ocular Side Effects of Systemic Medications, January 2008.)
A subjective take-home or in-office questionnaire is generally the best assessment to determine if visual dysfunction is affecting the patients life, potentially endangering the patient or others. It may also help determine the appropriate time for surgical intervention.
Once the subjective visual function examination is complete, you must perform a series of standardized objective tests to determine if the patient should undergo cataract surgery.14 These tests reveal the level of visual function and ocular health, help rule out any coexisting ophthalmic diseases, and establish a basis to measure surgical outcomes.
The basic examination includes:
Measurement of visual acuity under both low and high illumination. You may include contrast sensitivity functions and acuity testing in contrast methods using logMAR charts or glare reduction methods.
Visual acuity is the single most important component of overall visual function. The patients visual acuity level will generally influence the decision to proceed with cataract surgery. We generally proceed with surgery when a patients vision is between 20/40 and 20/50, or worse. Yet, either the patient or his or her guardian/custodian must make the final decision for surgery.
Corneal evaluation. Several corneal tests are highly recommended to uncover any potential postoperative pathological concerns. Pachymetry should be performed to determine corneal thickness, which may be predictive of postoperative corneal edema.
Also, specular endothelial photography reveals endothelial cell morphology. As the cornea ages, the integrity of the endothelium is compromised, as evidenced by increased polymegathism and pleomorphism. The normal endothelium has an average cell count of 2,200 to 2,400 vs. abnormal endothelium, which has a low cell count of 1,200 to 1,500; the latter would be suspect for postoperative concerns.
Corneal endothelial compromise can be observed in many instances after a prolonged surgical time, or if there is a pre-existing corneal dystrophy or degeneration. Additionally, corneal edema can readily occur with an associated pressure spike due to residual viscoelastic agents, and is easily treated with a short term anti-glaucoma agent, such as Alphagan P(brimonidine tartrate, Allergan).
Corneal topography assists in determining whether the patient has either lenticular or corneal astigmatism. Topography also reveals subclinical corneal anomalies that may not be obvious to a patient with reduced vision, but may create more visible distortions and aberrations once the new implant is in place. Topography can assess lid position pre- and postoperatively, and can document lid anomalies, such as severe age-related ptosis.
Neuro-ophthalmic status. You may want to examine the neuro-ophthalmic status of the patients eyes to check for a differential lenticular interference vs. true coexisting ophthalmic disease. Your assessment should measure pupil function, color vision and threshold visual fields.
Biomicroscopy with pupillary dilation. This allows you to accurately assess the type and formation of the lenticular opacity and grade it based on the Lens Opacities Classification System (LOCS) or Oxford Clinical Cataract Classification and Grading System standardization.
Take a photograph of the cataract to match to the LOCS standards, which allows you to document pupil size and function. This is important because of the potential need to utilize iris retractors on small pupils postoperatively.
Iris transillumination and gonioscopy. Perform iris transillumination to determine if there is any form of pigment dispersion syndrome. Additionally, a baseline gonioscopy is required, particularly in cases of pigment dispersion, narrow angles, and pseudoexfoliation or trauma.
A rigorous funduscopic exam. This is mandatory to rule out other retinal abnormalities. Cataract surgery always becomes controversial whenever macular degeneration, retinopathy or vascular occlusive disease is present. If you find any retinal disease, treat it first, and then consider referring the patient for the cataract procedure.
Ultrasonography. This lets you (or the surgeon) determine the patients axial length O.U. The average axial length is approximately 24.5mm to 26.5mm. An error of 1mm in the measurement can create an error of 3.00D in the final intraocular lens (IOL) calculation. Depending on the device, you may be able to make an approximate IOL calculation. Nevertheless, you need to have a detailed discussion with the surgeon about any IOL recommendations.
Fundus image of a grape 3 nuclear sclerotic cataract (left) and a biomicroscopy image of a cortical cataract (right).
After all examinations are completed, you must discuss your findings with both the patient and the surgeon. Review the definition of a cataract, the subjective visual function issues, the objective assessment, what surgical options are appropriate, and what the alternative treatments may be.
Potential Cataract Surgery Complications Possible intraoperative complications: Tearing of the back part of the lens capsule, with disturbance of the gel inside the eye. This may result in reduced vision or problems associated with implant placement. Loss of all or part of the cataract into the back of the eye. This will necessitate additional surgical intervention. Blood collection inside the eye. Difficult or improper implant placement, with secondary visual disturbance. Possible postoperative complications: Bruising of the eye or eyelids. High pressure inside the eye. Clouding of the cornea. Incorrect strength or dislocation of the IOL. Macular edema. Detached retina, which can lead to loss of sight. Infection of the eye, which can lead to vision loss or a compromised globe. Allergy to the medication used.
You should also discuss the informed consent document, which covers the specifics of the surgical procedure and details the duties of each involved party. When comanaging surgical patients, they must sign an informed consent on whom will be tending to their care. Preoperative and postoperative documentation must be shared with the all involved parties.
Visual variances associated with healing, implant design and/or position.
Lens capsule opacity called an after cataract, which is easily treated with a YAG laser (as needed).
Be certain to inform your patient of the potential complications associated with the surgery (see Potential Cataract Surgery Complications, left). Also, specifically outline all postoperative lifestyle limitations, such as avoiding heavy lifting, swimming, or contact with chemicals, and review a list of medications the patient will have to use following surgery.
Once this process is complete, both the surgeon and primary care physician will examine the patient. The patient should have medical clearance from his or her primary care physician before undergoing cataract surgery to rule out any unknown co-morbid disease.
Also, the patient should have a complete blood work evaluation, chest X-ray, urinanalysis, and a cardiac and respiratory function analysis. These simple tests, which may not have been done in years, could save a persons life. Outpatient surgery centers may have different policies than hospital-based centers. Assume the same basic requirements.
Then, a full summary report with lab and primary care physician clearance needs to be transferred to the surgeon for his or her assessment. At this juncture, the surgeon will develop a plan and initiate scheduling and comanagement with the optometrist.
Cataracts are one of the most common, and in many cases, somewhat preventable ocular disorder. Appropriate education and proper adherence to strict guidelines of clinical care benefit both you and your patients. It is up to you to fully comanage the patient through both non-surgical and surgical intervention. To be responsible and effective when preoperatively comanaging cataract patients, you must try to be as versed in ocular surgical care as an ophthalmologist.
A cataract patient who receives proper education and timely care will have a better postoperative outcome and will be satisfied with his or her overall ocular health and visual status.
Dr. Daniels is in private practice in
1. Congdon N, Vingerling JR, Klein BE, et al. Prevalence of cataract and pseudophakia/aphakia among adults in the
2. Klein BE, Klein R, Lee KE. Incidence of age-related cataract: the Beaver Dam Eye Study. Arch Ophthalmol 1998 Feb;116(2):219-25.
3.
4. Taylor A. Effect of photooxidation of the lens and role of
nutrients in delaying cataract. In: Emerit I, Chance B, eds. Free Radicals and Aging of the Skin.
5. Spector A. Oxidative stress-induced cataract: mechanism of action. FASEB J 1995 Sep;9(12):1173-82.
6. Taylor HR,
7. Bartlett JD, Jaanus SD. Ocular effects of systemic drugs. In:
8. Cumming RG, Mitchell P, Leeder SR. Use of inhaled corticosteroids and the risk of cataracts.
9. Chynn EW, Regan A, Ferris FL. Smoking and the Eyes. In: Cigarettes: What the Warning Label Doesnt Tell You.
10. Cekic O. Effect of cigarette smoking on copper, lead, and cadmium accumulation in human lens Br J Ophthalmol 1998 Feb;82(2):186-8.
11. Cumming RG, Mitchell P. Alcohol, smoking, and cataracts: the Blue Mountains Eye Study. Arch Ophthalmol 1997 Oct;115(10):1296-303.
12. Munoz B, Tajchman U, Bochow T, West S. Alcohol use and risk of posterior subcapsular opacities. Arch Ophthalmol 1993 Jan;111(1):110-2.
13. Van Heyningen R, Harding JJ. A case-control study of cataract in Oxfordshire: some risk factors. Br J Ophthalmol 1988 Nov;72(11):804-8.
14. American Optometric Association. Optometric Clinical Practice Guideline: Care of the Adult Patient with Cataract. Revised: 2004. Available at: www.aoa.org/documents/CPG-8.pdf (Accessed April 10, 2008).
