Senile cataract is an age-related, vision-impairing disease characterized by gradual progressive clouding and thickening of the lens of the eye. It is the world’s leading cause of treatable blindness.
See What the Eyes Tell You: 16 Abnormalities of the Lens, a Critical Images slideshow, to help recognize lens abnormalities that are clues to various systemic conditions and diseases.
A patient with senile cataract often presents with a history of gradual progressive visual deterioration and disturbance in night and near vision. Characteristic symptoms of senile cataract include the following:
See Clinical Presentation for more detail.
A complete ocular examination must be performed, beginning with visual acuity for near and far distances. When the patient complains of glare, visual acuity should be tested in a brightly lit room. Contrast sensitivity may also be checked, especially if the history points to a possible problem.
Diagnosis can also include the following:
Ocular imaging studies such as ultrasonography, computed tomography (CT) scanning, or magnetic resonance imaging (MRI) are requested when a significant posterior pole pathology is suspected and an adequate view of the back of the eye is obscured by a dense cataract.
Staging
Clinical staging of senile cataract is traditionally based on the appearance of the lens on slit-lamp examination, as follows:
Clinical staging of senile cataract can also be based on the visual acuity of the patient, as follows:
See Workup for more detail.
Lens extraction is the definitive treatment for senile cataract. It can be accomplished via the following procedures:
Intraocular lens (IOL) implantation is customarily used in combination with each of these techniques, although ECCE and phacoemulsification allow for more advantageous anatomical placement of the IOL than does ICCE.
See Treatment and Medication for more detail.
Senile cataract is a vision-impairing disease characterized by gradual, progressive thickening of the lens. It is the leading cause of blindness in the world today. This is unfortunate, considering that the visual morbidity brought about by age-related cataract is reversible. As such, early detection, close monitoring, and timely surgical intervention must be observed in the management of senile cataracts. Even greater challenges abound in economically disadvantaged and geographically isolated regions where limited healthcare access precludes early intervention. The subsequent section is a general overview of senile cataract and its management.
The pathophysiology behind senile cataracts is complex and yet to be fully understood. In all probability, its pathogenesis is multifactorial involving complex interactions between various physiologic processes modulated by environmental, genetic, nutritional, and systemic factors. As the lens ages, its weight and thickness increases while its accommodative power decreases. As the new cortical layers are added in a concentric pattern, the central nucleus is compressed and hardened in a process called nuclear sclerosis.
Multiple mechanisms contribute to the progressive loss of transparency of the lens. The lens epithelium is believed to undergo age-related changes, particularly a decrease in lens epithelial cell density and an aberrant differentiation of lens fiber cells. Although the epithelium of cataractous lenses experiences a low rate of apoptotic death, which is unlikely to cause a significant decrease in cell density, the accumulation of small scale epithelial losses may consequently result in an alteration of lens fiber formation and homeostasis, ultimately leading to loss of lens transparency. Furthermore, as the lens ages, a reduction in the rate at which water and, perhaps, water-soluble low-molecular weight metabolites can enter the cells of the lens nucleus via the epithelium and cortex occurs with a subsequent decrease in the rate of transport of water, nutrients, and antioxidants.
Consequently, progressive oxidative damage to the lens with aging takes place, leading to senile cataract development. Various studies showing an increase in products of oxidation (eg, oxidized glutathione) and a decrease in antioxidant vitamins and the enzyme superoxide dismutase underscore the important role of oxidative processes in cataractogenesis.
Another mechanism involved is the conversion of soluble low-molecular weight cytoplasmic lens proteins to soluble high molecular weight aggregates, insoluble phases, and insoluble membrane-protein matrices. The resulting protein changes cause abrupt fluctuations in the refractive index of the lens, scatter light rays, and reduce transparency. Other areas being investigated include the role of nutrition in cataract development, particularly the involvement of glucose and trace minerals and vitamins.
Senile cataract can be classified into 3 main types: nuclear cataract, cortical cataract, and posterior subcapsular cataract. Nuclear cataracts result from excessive nuclear sclerosis and yellowing, with consequent formation of a central lenticular opacity. In some instances, the nucleus can become very opaque and brown, termed a brunescent nuclear cataract. Changes in the ionic composition of the lens cortex and the eventual change in hydration of the lens fibers produce a cortical cataract. Formation of granular and plaquelike opacities in the posterior subcapsular cortex often heralds the formation of posterior subcapsular cataracts.
In the Framingham Eye Study from 1973-1975, senile cataract was seen in 15.5% of the 2477 patients examined. The overall rates of senile cataract in general, and of its 3 main types (ie, nuclear, cortical, posterior subcapsular), rapidly increased with age; for the oldest age group (≥75 y), nuclear, cortical, and posterior subcapsular cataracts were found in 65.5%, 27.7%, and 19.7% of the study population, respectively. Nuclear opacities were the most commonly seen lens change.
An updated study by the Wilmer Eye Institute in 2004 noted that approximately 20.5 million (17.2%) Americans older than 40 years had a cataract in either eye and 6.1 million (5.1%) were pseudophakic/aphakic.[1] These numbers are expected to rise to 30.1 million cataracts and 9.5 million cases with pseudophakia/aphakia by 2020.
Prevent Blindness America currently estimates that more than 22 million Americans aged 40 years and older have a cataract. An average of 3 million Americans undergo cataract surgery every year, with a 95% success rate of obtaining a best corrected vision of 20/20-20/40.
Senile cataract continues to be the main cause of visual impairment and blindness in the world. In recent studies performed in China,[2, 3] Canada,[4] Japan,[5] Denmark,[6] Argentina,[7] and India,[8] cataract was identified as the leading cause of visual impairment and blindness, with statistics ranging from 33.3% (Denmark) to as high as 82.6% (India). Published data estimate that 1.2% of the entire population of Africa is blind, with cataract causing 36% of this blindness. In a survey conducted in 3 districts in the Punjab plains, the overall rates of occurrence of senile cataract was 15.3% among 1269 persons examined who were aged 30 years and older and 4.3% for all ages. This increased markedly to 67% for ages 70 years and older. An analysis of blind registration forms in the west of Scotland showed senile cataract as 1 of the 4 leading causes of blindness.
Most morbidity associated with senile cataracts occurs postoperatively and is discussed in further detail later. Failure to treat a developing cataract surgically may lead to devastating consequences, such as lens swelling and intumescence, secondary glaucoma, and, eventually, blindness.
While the risk of dying as a result of cataract extraction is almost negligible, studies have shown an increased risk of mortality in patients who underwent surgery. In a comparison of 167 patients aged 50 years or older who underwent cataract extraction at the New England Medical Center in a period of 1 year to 824 patients who elected 1 of 6 other surgical procedures, it was found that the former had almost twice the mortality of the latter. Further analysis showed no significant correlation between diabetes and increased mortality. In a similar 5-year mortality analysis, patients with cataracts who were younger than 75 years had significantly higher age-specific rates of mortality than would be expected from US life tables.
These data imply an association between senile cataracts and increased mortality. Meddings et al suggest that senile cataract may be a marker of generalized tissue aging, which may be independent of cumulative ultraviolet exposure.[9] Hirsch and Schwartz who proposed the concept that senile cataracts reflect systemic phenomena rather than only a localized ocular disease share this view.[10]
Although race has been suggested as a possible risk factor for senile cataract, scarce literature exists to prove this theory. However, it has been observed that unoperated cataracts account for a higher percentage of blindness among blacks compared to whites. Instead, various other correlates may explain racial disparities, including medical comorbidities such as diabetes mellitus or lifetime ultraviolet (UV) exposure due to occupation, altitude, or latitude.
Studies on the prevalence of senile cataract between males and females have yielded contrasting results.
In the Framingham Eye Study from 1973-75, females had a higher prevalence than males in both lens changes (63% vs 54.1%) and senile cataract (17.1% vs 13.2%).
Sperduto and Hiller noted that each of the 3 types of senile lens opacities was found more often in women than in men.[11] In a separate investigation by Nishikori and Yamomoto, the male-to-female ratio was 1:8 with a female predominance in patients older than 65 years who were operated on for senile cataract.[12]
In a hospital-based, case-control study of senile cataract conducted in Japan, it was observed that an increased risk of cataract was found in males who were presently spending 7 hours or more outdoors and in females with 4 or fewer remaining teeth. However, in another analysis by Martinez et al, no sexual difference was noted in the prevalence of senile cataract.[13]
Age is an important risk factor for senile cataract. As a person ages, the chance of developing a senile cataract increases. In the Framingham Eye Study from 1973-1975, the number of total and new cases of senile cataract rose dramatically from 23.0 cases per 100,000 and 3.5 cases per 100,000, respectively, in persons aged 45-64 years to 492.2 cases per 100,000 and 40.8 cases per 100,000 in persons aged 85 years and older.
In the absence of any other accompanying ocular disease prior to surgery that would affect significantly the visual outcome (eg macular degeneration or optic nerve atrophy), a successful uncomplicated standard ECCE or phacoemulsification carries a very promising visual prognosis of gaining at least 2 lines in the Snellen distance vision chart. The main cause of visual morbidity postoperatively is CME. A major risk factor affecting visual prognosis is the presence of diabetes mellitus and diabetic retinopathy.
To date, no established guidelines are available for the prevention of senile cataracts. Education programs are geared toward early detection and surgical intervention when vision is impaired functionally. With the advent of phacoemulsification, patients are advised against delaying lens extraction to the point when the cataract is hard and mature and the likelihood of postoperative complications increases.
For patient education resources, see the Eye and Vision Center and Cataracts.
Careful history taking is essential in determining the progression and functional impairment in vision resulting from the cataract and in identifying other possible causes for the lens opacity. A patient with senile cataract often presents with a history of gradual progressive deterioration and disturbance in vision. Such visual aberrations are varied depending on the type of cataract present in the patient.
Decreased visual acuity is the most common complaint of patients with senile cataract. The cataract is considered clinically relevant if visual acuity is affected significantly. Furthermore, different types of cataracts produce different effects on visual acuity.
For example, a mild degree of posterior subcapsular cataract can produce a severe reduction in visual acuity with near acuity affected more than distance vision, presumably as a result of accommodative miosis. However, nuclear sclerotic cataracts often are associated with decreased distance acuity and good near vision.
A cortical cataract generally is not clinically relevant until late in its progression when cortical spokes compromise the visual axis. However, instances exist when a solitary cortical spoke occasionally results in significant involvement of the visual axis.
Increased glare is another common complaint of patients with senile cataracts. This complaint may include an entire spectrum from a decrease in contrast sensitivity in brightly lit environments or disabling glare during the day to debilitating glare with oncoming headlights at night.
Such visual disturbances are prominent particularly with posterior subcapsular cataracts and, to a lesser degree, with cortical cataracts. It is associated less frequently with nuclear sclerosis. Many patients may tolerate moderate levels of glare without much difficulty, and, as such, glare by itself does not require surgical management.
The progression of cataracts may frequently increase the dioptric power of the lens resulting in a mild-to-moderate degree of myopia or myopic shift. Consequently, presbyopic patients report an increase in their near vision and less need for reading glasses as they experience the so-called second sight. However, such occurrence is temporary, and, as the optical quality of the lens deteriorates, the second sight is eventually lost.
Typically, myopic shift and second sight are not seen in cortical and posterior subcapsular cataracts. Furthermore, asymmetric development of lens-induced myopia may result in significant symptomatic anisometropia that may itself require surgical management.
At times, the nuclear changes are concentrated in the inner layers of the lens, resulting in a refractile area in the center of the lens, which often is seen best within the red reflex by retinoscopy or direct ophthalmoscopy.
Such a phenomenon, which some call “lens within a lens phenomenon,” may lead to monocular diplopia that is not correctable with spectacles, prisms, or contact lenses.
After a thorough history is taken, careful physical examination must be performed. The entire body habitus is checked for abnormalities that may point out systemic illnesses that affect the eye and cataract development.
A complete ocular examination must be performed beginning with visual acuity for both near and far distances. Whether or not the patient complains of glare, visual acuity should be tested in a brightly lit room or with one of the many commercially available glare-testing devices, such as the brightness acuity tester (BAT). Contrast sensitivity may also be checked, especially if the history points to a possible problem.
Examination of the ocular adnexa and intraocular structures may also provide clues to the patient's disease and eventual visual prognosis.
A very important test is the swinging flashlight test, which is used to detect a Marcus Gunn pupil or relative afferent pupillary defect (RAPD), indicative of optic nerve lesions or severe diffuse retinal involvement. A patient with a RAPD and a cataract is expected to have a very guarded visual prognosis, even after uncomplicated cataract extraction.
A patient with long-standing ptosis since childhood may have occlusion amblyopia, which may account more for the decreased visual acuity rather than the cataract. Similarly, a careful history regarding visual acuity in each eye during childhood, checking for problems in ocular motility in all directions of gaze, as well as anisometropia, is important to rule out any other amblyogenic causes for the patient's visual symptoms.
Slit lamp examination should not only concentrate on evaluating the lens opacity but the other ocular structures as well (eg, conjunctiva, cornea, iris, anterior chamber). Corneal thickness and the presence of corneal opacities, such as corneal guttate, must be checked carefully. Appearance of the lens must be noted meticulously before and after pupillary dilation.
The visual significance of oil droplet nuclear cataracts and small posterior subcapsular cataracts is evaluated best with a normal-sized pupil to determine if the visual axis is obscured. However, exfoliation syndrome is best appreciated with the pupil dilated, revealing exfoliative material on the anterior lens capsule, as well as the pupillary margin, trabecular meshwork, and other intraocular structures.
After dilation, nuclear size and brunescence as indicators of cataract density can be determined prior to phacoemulsification surgery. The lens position and integrity of the zonular fibers also should be checked because lens subluxation may indicate previous eye trauma, antecedent ocular surgery, metabolic disorders, or hypermature cataracts.
The importance of direct and indirect ophthalmoscopy in evaluating the integrity of the posterior pole must be underscored. Optic nerve and retinal problems may account for the visual disturbance experienced by the patient. Furthermore, the prognosis after lens extraction is affected significantly by preoperative detection of pathologies in the posterior pole (eg, macular edema, retinal dystrophy, optic atrophy, severe glaucomatous cupping, age-related macular degeneration) and in the retinal periphery (eg, retinal breaks or extensive vitreoretinal traction).
Numerous studies have been conducted to identify risk factors for development of senile cataracts. Various culprits have been implicated, including environmental conditions, systemic diseases, UV exposure, diet, and age.[14, 15]
West and Valmadrid stated that age-related cataract is a multifactorial disease with different risk factors associated with each of the different cataract types.[16] In addition, they stated that cortical and posterior subcapsular cataracts were related closely to environmental stresses, such as UV exposure, diabetes, and drug ingestion. However, nuclear cataracts seem to have a correlation with smoking. Alcohol use has been associated with all cataract types.
A similar analysis was completed by Miglior et al.[17] They found that cortical cataracts were associated with the presence of diabetes for more than 5 years and increased serum potassium and sodium levels. A history of surgery under general anesthesia and the use of sedative drugs were associated with reduced risks of senile cortical cataracts. Posterior subcapsular cataracts were associated with steroid use and diabetes, while nuclear cataracts had significant correlations with calcitonin and milk intake. Mixed cataracts were linked with a history of surgery under general anesthesia.
In a population-based, longitudinal study of 3471 Latinos with 4 years of follow-up, Richter et al found that independent risk factors for incident nuclear-only lens opacities included older age, current smoking, and the presence of diabetes. Risk factors for cortical-only lens opacities included older age and having diabetes at baseline. Female gender was a risk factor for posterior subcapsular-only lens opacities. Presence of diabetes at baseline and older age were risk factors for mixed lens opacities.[18]
Senile cataracts have been associated with numerous systemic illnesses, to include the following: cholelithiasis, allergy, pneumonia, coronary disease and cardiac insufficiency, hypotension, hypertension, mental retardation, and diabetes.
Systemic hypertension was found to significantly increase the risk for posterior subcapsular cataracts. In a related study by Jahn et al, hypertriglyceridemia, hyperglycemia, and obesity were found to favor the formation of posterior subcapsular cataracts at an early age.[19]
A possible pathway for the role of hypertension and glaucoma in senile cataract formation was proposed with induced changes in the protein conformational structures in the lens capsules, subsequently causing alterations in membrane transport and permeability of ions, and, finally, increasing intraocular pressure resulting in the exacerbation of cataract formation.
The association of UV light and development of senile cataract has generated much interest. One hypothesis implies that senile cataracts, particularly cortical opacities, may be the result of thermal damage to the lens.
An animal model by Al-Ghadyan and Cotlier documented an increase in the temperature of the posterior chamber and lens of rabbits after exposure to sunlight due to an ambient temperature effect through the cornea and to increased body temperature.[20]
In related studies, people living in areas with greater UV exposure were more likely to develop senile cataracts and to develop them earlier than people residing in places with less UV exposure.
Significant associations with senile cataract were noted with increasing age, female sex, social class, and myopia. Consistent evidence from the study of West and Valmadrid suggested that the prevalence of all cataract types was lower among those with higher education.[16] Workers exposed to infrared radiation also were found to have a higher incidence of senile cataract development.
Although myopia has been implicated as a risk factor, it was shown that persons with myopia who had worn eyeglasses for at least 20 years underwent cataract extraction at a significantly older age than emmetropes, implying a protective effect of the eyeglasses to solar UV radiation.
The role of nutritional deficiencies in senile cataract has not been proven or established. However, a high intake of the 18-carbon polyunsaturated fatty acids linoleic acid and linolenic acid reportedly may result in an increased risk of developing age-related nuclear opacity.
In the Blue Mountains Eye Study, pseudoexfoliation increased the risk of cataract and subsequent cataract surgery.[21]
Diagnosis of senile cataract is made basically after a thorough history and physical examination are performed. Laboratory tests are requested as part of the preoperative screening process to detect coexisting diseases (eg, diabetes mellitus, hypertension, cardiac anomalies). Studies have shown that thrombocytopenia may lead to increased perioperative bleeding and, as such, should be properly detected and managed before surgery, especially if synechiolysis, a retrobulbar block, or an adjunctive procedure such as microincisional glaucoma surgery (MIGS) or pars plana vitrectomy is anticipated. Additional risk factors for accentuated perioperative bleeding should also be assessed, including the use of oral NSAIDs, anticoagulant prescription medications, or omega-3 supplements containing vitamin E (eg, fish oil).
Ocular imaging studies (eg, ultrasonography, CT scanning, MRI) can be requested when a posterior pole pathology is suspected and an adequate view of the back of the eye is obscured by an extremely dense or hypermature cataract. This is helpful in planning out the surgical management and in providing a more guarded postoperative prognosis for the visual recovery of the patient.
Additional patient-specific tests can be performed when coexisting ocular diseases are suspected, especially in identifying the etiology of preoperative visual loss. Aside from routine visual acuity testing, testing for brightness acuity and contrast sensitivity and confrontation visual field testing can be performed to assess visual function. Patients with a history of glaucoma, optic nerve disease, or retinal abnormality should undergo an automated visual field test to document the degree of preoperative field loss.
In patients suspected of having a macular problem, the following tests may be performed to evaluate macular function: Maddox rod test, photostress recovery test, blue-light entoptoscopy, Purkinje entoptic phenomenon, and visual-evoked response and electroretinography (VER-ERG). Above all, macular optical coherence tomography (OCT) should prove to be the most informative regarding structure.
In patients with dense cataracts that preclude adequate visualization of the fundus, a Maddox rod test can be used to grossly evaluate macular function with detection of a large scotoma, represented as a loss of the red line, a sign suggestive of a macular pathology.
While the photostress recovery test is a semiquantitative estimate of macular function, both blue-light entoptoscopy and Purkinje entoptic phenomenon are subjective means of evaluating macular integrity. The most objective method of measuring macular function is VER-ERG. A simple color vision test with a large Ishihara chart or muscle light illuminated color-coded glaucoma medication caps can also qualitatively predict intact macular function.
Several measurements should be taken preoperatively, particularly in an anticipated cataract extraction with intraocular lens (IOL) implantation.
Careful refraction must be performed on both eyes in selecting the IOL style, power, optics (spheric or aspheric), and premium features best suited to the individual eye. The power of the IOL on the operated eye must be compatible with the refractive error of the fellow eye to avoid complications (eg, postoperative anisometropia), while also anticipating future surgeries. Ocular dominance is also important since many patients tolerate a small degree of monovision with a small add or additional IOL plus power in the nondominant eye, often called mini-monovision.
An accurate biometry also should be performed to calculate for the IOL power to be used.
Corneal integrity, specifically the endothelial layer, must be assessed very well via pachymetry, slit lamp 40x high-magnification endothelial specular illumination, and specular microscopy to predict postoperative corneal morbidities (eg, corneal edema, corneal decompensation) and to weigh the risks versus the benefits of performing cataract extraction. A preoperative discussion of endothelial transplantation, however brief, is wise in the context of even minimal detected endothelial pathology.
Nuclear cataracts are characterized by homogeneity of the lens nucleus with loss of cellular laminations. Cortical cataracts typically manifest with hydropic swelling of the lens fibers with globules of eosinophilic material (morgagnian globules) seen in slit-like spaces between lens fibers. Finally, a posterior subcapsular cataract is associated with posterior migration of the lens epithelial cells in the posterior subcapsular area, with aberrant enlargement of the epithelial cells (Wedl or bladder cells).
Costello et al examined senile cataracts using electron microscopy to highlight differences in the cellular architecture of the various forms of age-related lens changes.[22] Comparisons were made between a typical nuclear cataract with a central opacity and a transparent rim, and a more advanced or mature, completely opaque nuclear cataract. The former was described as having no obvious cell disruption, cellular debris, or changes that could readily account for the central opacity. The fiber cells had intact uniformly stained cytoplasm with well-defined plasma membrane borders and gap junctions. The mature cataract exhibited various types of cell disruption in the perimeter but not in the core of the nucleus in the form of globules, vacuoles, multilamellar membranes, and clusters of highly undulating membranes.
Clinical staging of senile cataract is traditionally based on the appearance of the lens on slit-lamp examination, as follows:
Clinical staging of senile cataract can also be based on the visual acuity of the patient, as follows:
No time-tested, FDA-approved, or clinically proven medical treatment exists to delay, prevent, or reverse the development of senile cataracts.
Aldose reductase inhibitors, which are believed to inhibit the conversion of glucose to sorbitol, have shown promising results in preventing sugar cataracts in animals. Other anticataract medications being investigated include sorbitol-lowering agents, aspirin, glutathione-raising agents, and antioxidant vitamins C and E.
The definitive management for senile cataract is lens extraction. Over the years, various surgical techniques have evolved from the ancient method of couching to the present-day technique of modern phacoemulsification. Phacoemulsification offers the advantage of a smaller incision size at the time of cataract surgery.[23] Historically parallel to the development of phacoemulsification is the evolution of advanced IOL design, which offers a wide selection of target implantation locations, materials, chromophores, premium features, and manner of implantation. Differentiated by the integrity of the posterior lens capsule, the 2 main types of lens surgery are the intracapsular cataract extraction (ICCE) and the extracapsular cataract extraction (ECCE). Below is a general description of the 3 commonly used surgical procedures in cataract extraction, namely ICCE, standard ECCE, and phacoemulsification. Referencing literature dedicated specifically to cataract surgeries for a more in-depth discussion of the topic, particularly with regard to technique and procedure, is also recommended.
Results from a large database study by Lundström et al indicate that poor visual outcome following surgery is most strongly determined by the following factors[24, 25] :
Data (some self-reported) for the study were drawn from the European Registry of Quality Outcomes for Cataract and Refractive Surgery, which contained information on 368,256 cataract extractions. According to the investigators, although cataract surgery yielded excellent visual outcomes for more than 60% of patients in the study, vision was unchanged in 5.7% of them, while 1.7% of patients experienced a decrease in corrected distance visual acuity (CDVA).[24, 25]
Prior to the onset of more modern microsurgical instruments and better IOLs, ICCE was the preferred method for cataract removal. It involves extraction of the entire lens, including the posterior capsule and mechanical or enzymatic lysis of the zonular support structures. In performing this technique, there is no need to worry about subsequent development and management of capsular opacity. The technique can be performed with less sophisticated equipment and in areas where operating microscopes and irrigating systems are not available.
However, a number of disadvantages and postoperative complications accompany ICCE. The larger limbal incision, often 160°-180°, is associated with the following risks: delayed healing, delayed visual rehabilitation, significant against-the-rule astigmatism, iris incarceration, postoperative wound leaks, and vitreous incarceration. Corneal edema is a common postoperative complication.
Furthermore, endothelial cell loss is greater in ICCE than in ECCE. The same is true about the incidence of postoperative cystoid macular edema (CME) and retinal detachment. The broken integrity of the vitreous face can lead to postoperative complications, even after a seemingly uneventful operation. Finally, because the posterior capsule is not intact, the IOL to be implanted must be placed in the anterior chamber, sutured to the iris, or surgically fixated in the posterior chamber. Both techniques are more difficult to perform than simply placing an IOL in the capsular bag and are associated with postoperative complications, the most notorious of which is pseudophakic bullous keratopathy (PBK).
Although the myriad postoperative complications has led to the decline in popularity and use of ICCE, it still can be used when zonular integrity is too severely impaired to allow successful lens removal and IOL implantation with an ECCE, particularly carefully selected posttraumatic and hypermature cataracts. Furthermore, ICCE can be performed in remote areas where more sophisticated equipment is not available.
ICCE is contraindicated in children and young adults with cataracts and any case with traumatic capsular rupture where intact removal of the lens capsule unit may prove difficult or incomplete. Relative contraindications include high myopia, Marfan syndrome, morgagnian cataracts, and vitreous presenting in the anterior chamber. Many of these patients may benefit from a pars plana lensectomy by a vitreoretinal surgeon prior to implantation of the appropriate IOL type.
In contrast to ICCE, ECCE involves the removal of the lens nucleus through an opening in the anterior capsule with retention of posterior capsular integrity. ECCE possesses a number of advantages over ICCE, most of which are related to an intact posterior capsule, as follows:
The main requirements for a successful ECCE and endocapsular IOL implantation are zonular integrity and an intact posterior capsule. As such, when zonular support is insufficient or appears suspect to allow a safe removal of the cataract via ECCE, ICCE or pars plana lensectomy should be considered.
Standard ECCE and phacoemulsification are similar in that extraction of the lens nucleus is performed through an opening in the anterior capsule or anterior capsulotomy. Both techniques also require mechanisms to irrigate and aspirate fluid and cortical material during surgery. Finally, both procedures place the IOL within the capsular bag, which is far more anatomically correct than the anteriorly placed IOL.
Needless to say, significant differences exist between the 2 techniques. Removal of the lens nucleus in ECCE can be performed manually in standard ECCE or with an ultrasonically driven needle to fragment the nucleus of the cataract and then to aspirate the lens substrate through a needle port in a process termed phacoemulsification.
The more modern of the 2 techniques, phacoemulsification offers the advantage of using smaller incisions, minimizing complications arising from improper wound closure, and affording more rapid wound healing and faster visual rehabilitation. Furthermore, it uses a relatively closed system during both phacoemulsification and aspiration with better control of intraocular pressure during surgery, providing safeguards against positive vitreous pressure and choroidal hemorrhage. A closed system also minimizes fluid turbulence within the anterior chamber, reducing endothelial and trabecular meshwork trauma. However, more sophisticated and expensive machines, disposables, and instruments are required to perform phacoemulsification.
Ultimately, the choice of which of the 2 procedures to use in cataract extraction depends on the patient, the type of cataract, the availability of the proper instruments, and the degree to which the surgeon is comfortable and proficient in performing standard ECCE or phacoemulsification. The vast majority of modern cataract surgeons perform and prefer phacoemulsification.
The surgeon should also consider whether to use topical or regional anesthesia during the procedure. A study by Zhao et al examined the clinical outcomes of topical anesthesia and regional anesthesia including retrobulbar anesthesia and peribulbar anesthesia in phacoemulsification. The authors found that regional anesthesia provides better perioperative pain control, but that surgical outcomes were the same for both.[26]
Although single-eye cataract surgery improves vision, including the second eye may yield greater rewards, according to a prospective, population-based study by Lee et al. The investigators studied 1739 participants aged 65-84 years at enrollment, 90 of whom following enrollment had unilateral cataract surgery, and 29 of whom had bilateral surgery. In the 1620 patients who did not undergo surgery, bilateral baseline best-corrected visual acuity logarithm of the minimum angle of resolution (BCVA of logMAR) was no greater than 0.3 (at least 20/40).[27, 28]
BCVA of logMAR improved by 0.04 in the unilateral group and 0.13 in the bilateral group, while reading speed increased by 12 words per minute in the unilateral group and 31 words per minute in the bilateral group. Moreover, the Activities of Daily Vision Scale scores (measuring vision at a distance, close-up, glare, and day and night driving) showed a 5-point relative improvement in the bilateral group, while the unilateral group actually showed a 5-point relative decrease.
An increased risk for intraoperative floppy iris syndrome (IFIS) was observed during cataract surgery in patients with benign prostatic hypertrophy (BPH) who were taking a nonselective alpha1-antagonist. Alfuzosin and tamsulosin, 2 drugs commonly used to treat BPH, are both linked to permanent changes in the iris and associated with an increased risk of IFIS. A prospective, masked, cross-sectional multicenter study by Chang et al determined that patients taking systemic alfuzosin for BPH were less likely to experience moderate or severe IFIS during cataract surgery than patients taking tamsulosin.[29, 30]
Of the 226 eyes studied, 70 were in patients receiving systemic tamsulosin, 43 in patients receiving systemic alfuzosin, and 113 in patients with no history of systemic alpha1-antagonist therapy.[30] The incidence of IFIS was 34.3% in the tamsulosin group, 16.3% in the alfuzosin group, and 4.4% in the control group. Severe IFIS was statistically more likely with tamsulosin than with alfuzosin (P = 0.036). Thus, patients with symptomatic BPH and cataracts requiring a uroselective alpha1-antagonist may consider trying alfuzosin first.
Bell et al reviewed exposure to alpha-adrenergic blockers frequently prescribed to treat benign prostatic hypertrophy (BPH) and their association with serious intra-operative adverse effects during cataract surgery.[31] The study included more than 96,000 older men who had cataract surgery over a 5-year period (3.7% had recent exposure to tamsulosin and 7.7% had recent exposure to other alpha blockers). Exposure to tamsulosin within 14 days of cataract surgery was significantly associated with serious postoperative ophthalmic adverse events (7.5% vs 2.7%; adjusted odds ratio [OR], 2.33; 95% confidence interval [CI], 1.22-4.43), specifically intraoperative floppy iris syndrome and its complications (ie, retinal detachment, lost lens or fragments, uveitis, endophthalmitis).A study by Baker et al found that 23-gauge pars plana vitrectomy is a possible surgical management approach in select cases of retained lens fragments. While 12 patients were successfully treated by this initial intervention, 8 required sclerotomy enlargement to a 20-gauge access.[32]
An association between cataract surgery and late age-related macular degeneration, independent of additional risk factors, has been shown in some studies.[33] Most surgeons do not believe that cataract extraction accelerates the onset of age-related macular degeneration. UV protection with sunglasses and hats is always recommended following cataract extraction.
Multifocal IOLs after cataract extraction are more effective at improving near vision than monofocal IOLS are, but whether this improvement outweighs the potential adverse effects of multifocal lenses varies between patients.[34] Careful patient selection to recommend a multifocal IOL only to patients with a pristine macula and ocular surface can be very rewarding for both the clinician and patient.
In 2008, the US Food and Drug Administration (FDA) approved the Alcon line of acrylic toric IOLs. In 2013, the FDA approved Abbott's Tecnis Toric 1-piece IOL to treat preexisting astigmatism in patients with cataract.[35] Toric IOLs are used to manage corneal astigmatism in patients who have undergone cataract surgery and whose natural lenses have been removed. Unlike other devices on the market, this 1-piece IOL can correct loss of focus of 1 diopter or greater. Clinical data show that the device offers exceptional rotational stability while improving visual results and improving distance and night vision.
In early 2014, the FDA approved a synthetic polyethylene glycol hydrogel sealant (ReSure Sealant, Ocular Therapeutix, Inc) for use in cataract surgery with IOL placement.[36] The sealant is indicated for prevention of postoperative fluid egress from incisions with a demonstrated wound leak after cataract surgery. Approval was based on a prospective, randomized, controlled multicenter study of 471 patients in which the sealant was more effective than a single suture in preventing incision leakage in the 7 days after surgery.
Prior to surgery, a thorough preoperative evaluation must be conducted, which would also include a thorough explanation of the procedure to be performed and its accompanying risks.
Not all senile cataracts require removal at the time of diagnosis. If vision, performance of daily tasks, and quality of life are not impaired significantly or if the patient is not prepared medically, psychologically, and financially for surgery, periodic consultations are encouraged to assess progression of the cataract. The procedure is, by definition, almost always elective. Very rarely, lens-induced glaucoma or uveitis warrants urgent or emergent cataract surgery.
Postoperatively, regular follow-up visits are necessary to monitor visual rehabilitation, as well as to detect and address any immediate and late complications arising from the surgery.
In relation to the surgery, no established dietary restrictions exist that would affect the course of the operation when a small corneal incision technique is planned. Larger scleral incisions, MIGS, simultaneous pars plana vitrectomy, or a planned retrobulbar anesthetic may dictate limitation of any dietary supplement (eg, fish oil) that may prolong bleeding times 2 weeks prior to surgery.
After surgery, the patient is dissuaded from performing activities that would increase the intraocular pressure, especially after undergoing ICCE or standard ECCE. These activities include lifting heavy loads, chronic vigorous coughing, and straining. Similarly, trauma and exposure to toxic fumes or particular matter should specifically be avoided.
Major intraoperative complications encountered during cataract surgery include the following:
Major immediate postoperative complications encountered during cataract surgery often seen within a few days or weeks after the operation include the following:
Major late postoperative complications seen weeks or months after cataract surgery include the following:
At any postoperative stage, the risk of uveitis, noninfectious endophthalmitis, and infectious endophthalmitis exists. Noninfectious endophthalmitis is believed to be a multifactorial process or an idiosyncratically variable response to a common factor, similar to a hypersensitivity reaction. Treatment may range from the use of topical, transseptal, or oral steroids to the rare explantation of the intraocular lens.
Although of low incidence, infectious endophthalmitis may lead to severe vision loss and blindness.[39] Staphylococcus epidermidis is the most commonly isolated organism in acute cases, and rupture of the posterior capsule is one of the most common risk factors.[39] Of late, a significant increase in the incidence of gram-positive bacteria in bacterial isolates from postoperative eyes suspected of having endophthalmitis has been observed. Furthermore, a significant increase in resistance to ciprofloxacin and other fluoroquinolones has occurred. Seemingly, the spectrum of bacteria causing postcataract endophthalmitis is changing, partly perhaps because of an increased resistance to mainstay antibiotics in the prevention of endophthalmitis. Delayed-onset infectious endophthalmitis is most commonly caused by Propionibacterium acnes.
Age is believed to be the most significant risk factor for senile cataract and, as such, it is essentially inevitable that some degree of lens opacity develops as one becomes older. No study has established firmly whether avoidance of some of the risk factors for senile cataract (eg, UV exposure, hypercholesterolemia, tobacco use, diabetes mellitus) will lessen the chance of developing a senile cataract.
On the first postoperative day, visual acuity should be consistent with the refractive state of the eye, the clarity of the cornea and media, and the visual potential of the retina and optic nerve. Mild edema of the eyelid may be evident, as well as some conjunctival injection. The cornea is normally clear with minimal edema and striae. The anterior chamber should be deep with mild cellular and flare reaction. It is important to check whether the posterior capsule is intact and whether the IOL is positioned properly. The red reflex must be strong and clear and the intraocular pressures should be within normal limits. Transient intraocular pressure elevations may be observed and are often attributed to retained viscoelastic material.
Significant improvement of these initial findings is to be expected in subsequent postoperative evaluation as the ocular inflammation subsides typically within 2 weeks. Topical steroids and antibiotics are tapered accordingly. Refraction is believed to be stable at the sixth to eighth postoperative week, at which time corrective lenses can be prescribed. Significant postoperative astigmatism following ECCE or ICCE can be addressed by suture removal after the sixth postoperative week as guided by keratometry, refraction, or corneal topography.
In a prospective, randomized, double-masked trial involving 59 patients undergoing cataract surgery, use of a tapered-release dexamethasone punctum plug after surgery, compared with the use of a placebo plug (Dextenza, Ocular Therapeutix), resulted in fewer cells in the anterior chamber (ie, less evidence of ocular inflammation), lower use of additional anti-inflammatory medications, and less light sensitivity.[40]
The mean pain score in the dexamethasone group on the first day following surgery was three times below that in the placebo group (0.6 vs 2.0), while the ocular pain score on day 14 was 11 times lower than that in the placebo patients. No long-term, plug-associated intraocular pressure spikes or adverse events were observed.
Most cataract surgeries are performed on an outpatient basis, especially with the widespread adoption of phacoemulsification performed under topical anesthesia. Often, patients are discharged from the clinic as soon as they have recovered from the emotional stress of the procedure. Patients are sent home on topical steroids, NSAIDs, and antibiotics either separately or in combination. An optional eye shield is placed on the newly operated eye and removed a few hours later.
During the postoperative period, the patient is prescribed a topical steroid such as 1% prednisolone acetate, which is applied every hour for the first day, then tapered depending on the inflammatory state of the eye. Studies have shown that topical ketorolac tromethamine provides adequate postoperative control of intraocular inflammation without the risk of increased intraocular pressure, which may be associated with steroid use. A broad-spectrum topical antibiotic also is given 4-6 times a day for 1-2 weeks.
No drug is available that has been proven to prevent the progression of senile cataracts. Medical therapy is used preoperatively and postoperatively to ensure a successful operation and subsequent visual rehabilitation.[41]
Clinical Context: Direct-acting adrenergic agent available in 2.5% and 10% concentrations. Acts locally as potent vasoconstrictor and mydriatic by constricting ophthalmic blood vessels and radial muscles of the iris. Favorably used by many ophthalmologists because of rapid onset and moderately prolonged action, as well as the fact that it does not produce compensatory vasodilation. Most ophthalmologists prefer 2.5% to 10% concentration because of fewer risks of severe adverse systemic effects. Onset of action is within 30-60 min lasting for 3-5 h.
Clinical Context: Tropicamide blocks the response of the sphincter muscle of the iris and the muscle of the ciliary body to cholinergic stimulation.
Autonomic drugs used to ensure maximal pupillary dilation preoperatively, which is essential for a successful lens extraction. Short-acting mydriatics often are used. Most commonly used mydriatics are phenylephrine hydrochloride and tropicamide.
Clinical Context: Nonsteroidal anti-inflammatory prodrug for ophthalmic use. Following administration, converted by ocular tissue hydrolases to amfenac, an NSAID. Inhibits prostaglandin H synthase (cyclooxygenase), an enzyme required for prostaglandin production. Indicated for treatment of pain and inflammation associated with cataract surgery.
Clinical Context: Nonsteroidal anti-inflammatory prodrug for ophthalmic use. Following topical administration, this NSAID achieves high therapeutic intraocular levels. Inhibits prostaglandin H synthase (cyclooxygenase), an enzyme required for prostaglandin production. Indicated for treatment of pain and inflammation associated with cataract surgery.
Clinical Context: Ketorolac/phenylephrine ophthalmic is a proprietary FDA-approved combination agent that is added to the standard irrigating solution used during cataract surgery and other intraocular lens replacement procedures, including refractive lens exchange. Phenylephrine is an alpha1-agonist that prevents intraoperative miosis and ketorolac is a nonsteroidal anti-inflammatory drug (NSAID) that facilitates mydriasis and reduces postoperative pain.
Combination allows for maintenance of intraoperative mydriasis and reduces postoperative pain.
Clinical Context: Topical anti-inflammatory agent for ophthalmic use. A good glucocorticoid that, on the basis of weight, has 3-5 times anti-inflammatory potency of hydrocortisone. Glucocorticoids act at the nuclear level by down-regulating transcription of inflammatory mediators. Thus, they reduce prostaglandin synthesis, block arachidonic acid activity, and inhibit edema, fibrin deposition, capillary dilation, and phagocytic migration of acute inflammatory response, as well as capillary proliferation, deposition of collagen, and scar formation. Indicated for treatment of steroid-responsive inflammation of palpebral and bulbar conjunctiva, cornea, and anterior segment of the globe.
Clinical Context: Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reducing capillary permeability.
Clinical Context: A potent corticosteroid approved for a wide variety of anterior segment surgical procedures, including cataract surgery, as well as acute noninfectious anterior uveitis. Provides powerful control of postoperative pain and inflammation in the cornea, anterior chamber, and, possibly, the retina.
Clinical Context: An ester rather than a ketone steroid, provides FDA-approved control of pain and inflammation following cataract surgery, as well as anterior uveitis, contact lens–induced giant papillary conjunctivitis, and perennial and seasonal allergic conjunctivitis. Newer ointment and gel drop formulations are approved for cataract surgery pain and inflammation.
Help decrease and control the inflammatory response following cataract surgery especially in the immediate postoperative period. The most commonly used ophthalmic steroid is prednisolone acetate 1%. Dexamethasone 0.1% ophthalmic solution sometimes is used as a generic alternative.
Clinical Context: Active against a broad spectrum of gram-positive and gram-negative organisms. Bactericidal action results from interference with enzyme DNA gyrase needed for bacterial DNA synthesis. In vitro and clinical studies have shown it to be active against following organisms: gram-positive (ie, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus viridans) and gram-negative (ie, Haemophilus influenzae, Pseudomonas aeruginosa, Serratia marcescens). Other organisms have been found to be susceptible in vitro but have yet to be firmly established by clinical studies.
Clinical Context: A self-preserved topical fluoroquinolone approved for conjunctivitis. Prescribed frequently for cataract and other intraocular surgical procedures as infection prophylaxis. By virtue of its broad spectrum and preservative-free status, many surgeons also inject 0.1 mL directly into the anterior chamber at the conclusion of cataract surgery to prevent endophthalmitis.
Clinical Context: A uniquely formulated fluoro-chloro fluoroquinolone that is bihalogenated for increased spectrum and potency. Highly effective against multiply drug-resistant strains of Staphylococcus aureus and Staphylococcus epidermidis. Not available for animal, farm, or systemic human use, presumably reducing resistance profiles. Excellent pharmacokinetics due to highly viscous Insite® vehicle.
Clinical Context: An increased spectrum L-isomer of ofloxacin provides antibiotic coverage for all types of intraocular surgery.
Clinical Context: A potent fluoroquinolone approved for bacterial conjunctivitis, like all the other listed fluoroquinolones herein, but used frequently for surgical prophylaxis.
Clinical Context: Indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections.
Clinical Context: A commonly prescribed topical combination agent used for conjunctivitis and surgical prophylaxis. Available as a generic.
Clinical Context: A commonly prescribed topical combination agent used for conjunctivitis and surgical prophylaxis. Much less likely to produce IOP elevations than dexamethasone-based combination agents.
Broad-spectrum antibiotic ophthalmic solutions often are used prophylactically off-label in the immediate postoperative period. A number of topical antibiotics are used depending on the surgeon's preference, but, generally, medications are active against both gram-positive and gram-negative organisms.