8
Lens
Richard A. Harper, MD
The (crystalline) lens contributes to focusing of images on the retina. It is positioned just posterior to the iris and is supported by zonular fibers arising from the ciliary body and inserting onto the equatorial region of the lens capsule (see Figure 1–12). The lens capsule is a basement membrane that surrounds the lens substance. Epithelial cells near the lens equator divide throughout life and continually differentiate into new lens fibers, so that older lens fibers are compressed into a central nucleus; younger, less-compact fibers around the nucleus make up the cortex. Because the lens is avascular and has no innervation, it must derive nutrients from the aqueous humor. Lens metabolism is primarily anaerobic owing to the low level of oxygen dissolved in the aqueous.
Accommodation is the eye’s ability to adjust its focus from distance to near due to changes of the shape of the lens. Its inherent elasticity allows the lens to become more or less spherical depending on the amount of tension exerted by the zonular fibers on the lens capsule. Zonular tension is controlled by the action of the ciliary muscle that, when contracted, relaxes zonular tension. The lens then assumes a more spherical shape, resulting in increased dioptric power to bring near objects into focus. Ciliary muscle relaxation reverses this sequence of events, causing the lens to flatten and bringing distant objects into view. As the lens ages, accommodation gradually reduces as lens elasticity decreases.
PHYSIOLOGY OF SYMPTOMS
Symptoms associated with lens disorders are primarily visual. Presbyopia is the reduced ability with age to perform near tasks due to decreased accommodation. Loss of lens transparency (cataract) results in blurred vision for near and distance. Surgical removal of the lens or its complete dislocation from the visual axis results in an aphakic refractive state; severely blurred vision results from
398
loss of over one-third of the eye’s refractive power, the majority still being provided by the curvature of the cornea.
The lens is best examined with the pupil dilated. A magnified view of the lens can be obtained with a slitlamp or by using the direct ophthalmoscope with a high plus (+10) setting.
CATARACT
The term cataract refers to any opacity in the lens. Aging is the most common cause, but many other factors can be involved, including trauma, toxins, systemic disease (such as diabetes), smoking, and heredity. Age-related cataract is a common cause of visual impairment. The prevalence of cataracts is around 50% in individuals age 65–74, increasing to about 70% for those over 75.
The pathogenesis of cataracts is incompletely understood. They are characterized by protein aggregates that scatter light and reduce transparency and other protein alterations that result in yellow or brown discoloration. Factors that contribute to cataract formation include oxidative damage (from free radical reactions), ultraviolet light damage, and malnutrition. No medical treatment has been established to retard or reverse the underlying chemical changes. At present, evidence for a protective effect from B vitamins, multivitamins, or carotenoids is inconclusive.
Most cataracts are not visible to the casual observer until they become dense enough to cause severe vision loss. On ophthalmoscopy, the ocular fundus becomes increasingly more difficult to visualize as the lens opacity becomes denser until the fundus reflection is completely absent. A mature cataract is one in which all of the lens substance is opaque; the immature cataract has some transparent regions. If the lens takes up water, it may become intumescent. In the hypermature cataract, cortical proteins have become liquid. This liquid may escape through the intact capsule, leaving a shrunken lens with a wrinkled capsule. A hypermature cataract in which the lens nucleus floats freely in the capsular bag is called a morgagnian cataract (Figure 8–1).
399
Figure 8–1. Age-related cataract. A and B: “Coronary” type cortical cataract (frontal and cross-sectional views): club-shaped peripheral opacities with clear central lens; slowly progressive. C: “Cuneiform” type cortical cataract: peripheral spicules and central clear lens; slowly progressive. D: Nuclear sclerotic cataract: diffuse opacity principally affecting nucleus; slowly progressive. E: Posterior subcapsular cataract: plaque of granular opacity on posterior capsule; may be rapidly progressive. F: “Morgagnian” type (hypermature lens): the entire lens is opaque, and the lens nucleus has fallen inferiorly.
400
The severity of cataract, assuming that no other eye disease is present, is judged primarily by the patient’s symptoms and the visual acuity. Generally speaking, the decrease in visual acuity is directly proportionate to the density of the cataract. However, some individuals who have clinically significant cataracts when examined with the ophthalmoscope or slitlamp see well enough to carry on with normal activities. Others have a decrease in visual acuity out of proportion to the observed degree of lens opacification. This is due to distortion of the image by the partially opaque lens or the cataract being located in the posterior visual axis. The Cataract Management Guideline Panel recommends reliance on clinical judgment combined with visual acuity as the best guide to the appropriateness of surgery but recognizes the need for flexibility, with due regard to a patient’s particular functional and visual needs, the environment, and other risks, all of which may vary widely.
AGE-RELATED CATARACT (FIGURES 8–1 AND 8–2)
Figure 8–2. Mature age-related cataract viewed through a dilated pupil.
Loss of clarity in the lens nucleus results in nuclear sclerosis. The earliest symptom may be improved near vision without glasses (“second sight”) due to increased refractive power of the central lens, creating a myopic (nearsighted) shift in refraction. Other symptoms may include poor hue discrimination, a need for increased light, and monocular diplopia. Most nuclear cataracts are bilateral but may be asymmetric.
Cortical cataracts are caused by changes in hydration of lens fibers creating clefts in a radial pattern around the equatorial region. They also tend to be bilateral, but they are often asymmetric. Visual function is variably affected, depending on how near the opacities are to the visual axis.
401
Posterior subcapsular cataracts are located in the cortex adjacent to the posterior capsule. They tend to cause visual symptoms earlier in their development owing to involvement of the visual axis. Common symptoms include glare and reduced vision under bright lighting conditions. This lens opacity can also result from trauma, corticosteroid use (topical or systemic), inflammation, or exposure to ionizing radiation.
Age-related cataract is usually slowly progressive. If surgery is indicated, lens extraction improves visual acuity in over 90% of cases. The remainder of patients either has preexisting retinal damage or, in rare cases, develops complications that prevent significant visual improvement, for example, intraocular hemorrhage perioperatively, or infection, retinal detachment, or glaucoma postoperatively.
CHILDHOOD CATARACT (FIGURES 8–3 AND 8–4)
Figure 8–3. Congenital cataract (right eye) with dilated pupils.
402
Figure 8–4. Congenital cataract, zonular type. One zone of lens involved. The cortex is relatively clear.
Childhood cataracts are divided into two groups: congenital (infantile) cataracts, which are present at birth or appear shortly thereafter, and acquired cataracts, which occur later and are usually related to a specific cause. Either type may be unilateral or bilateral.
About one-third of childhood cataracts are hereditary, while another third are secondary to metabolic or infectious diseases or associated with a variety of syndromes. The final one-third result from undetermined causes. Acquired cataracts arise most commonly from trauma, either blunt or penetrating. Other causes include uveitis, acquired ocular infections, diabetes, and drugs.
Clinical Findings
A. Congenital Cataract
Congenital lens opacities are common and often visually insignificant (see also Chapter 17). Opacity that is out of the visual axis or not dense enough to interfere significantly with light transmission requires no treatment other than observation. Dense central congenital cataracts require surgery.
Congenital cataracts that cause significant visual loss must be detected early, preferably in the newborn nursery by the pediatrician or family physician. Large, dense, white cataracts may present as leukocoria (white pupil), noticeable by the parents, but many dense cataracts cannot be seen by the parents. Unilateral infantile cataracts that are dense, central, and larger than 2 mm in diameter will cause permanent deprivation amblyopia if not treated within the first 2 months of life and thus require surgical management on an urgent basis. Even then, there must be careful attention to avoidance of amblyopia (see also Chapter 17) related to postoperative anisometropia (difference in focus power between the two eyes). Equally dense bilateral cataracts may require less-urgent management, although bilateral deprivation amblyopia can result. When surgery is undertaken, there must be as short an interval as is reasonably possible between treatment of the two eyes.
B. Acquired Cataract
Acquired cataracts often do not require the same urgent care (aimed at
403
preventing amblyopia) as infantile cataracts because the children are usually older and the visual system more mature. Surgical assessment is based on the location, size, and density of the cataract, but a period of observation along with subjective visual acuity testing is helpful. Because unilateral cataract in children will not produce any symptoms or signs that parents would routinely notice, screening programs are important for case finding.
TRAUMATIC CATARACT
Traumatic cataract (Figures 8–5 to 8–7) is most commonly due to a foreign body injury to the lens or blunt trauma to the eyeball. Air rifle pellets and fireworks are a frequent cause; less-frequent causes include arrows, rocks, contusions, and ionizing radiation. Most traumatic cataracts are preventable. In industry, the best safety measure is a good pair of safety goggles.
Figure 8–5. Traumatic “star-shaped” cataract in the posterior lens. This is usually due to ocular contusion and is only detectable through a well-dilated pupil.
404
Figure 8–6. Traumatic cataract with wrinkled anterior capsule.
Figure 8–7. Imprint of iris pigment on anterior surface of lens.
The lens usually becomes white soon after the entry of a foreign body, since interruption of the lens capsule allows fluid to penetrate into the lens structure. The patient often gives a history of striking metal upon metal. For example, a minute fragment of a steel hammer may pass through the cornea and lens and lodge in the vitreous or retina.
CATARACT SECONDARY TO INTRAOCULAR DISEASE (“COMPLICATED CATARACT”)
Cataract may develop as a direct effect of intraocular disease upon the physiology of the lens (eg, severe recurrent uveitis). The cataract usually begins in the posterior subcapsular area and may eventually involve the entire lens
405
structure. Intraocular diseases commonly associated with the development of cataracts are chronic or recurrent uveitis, glaucoma, retinitis pigmentosa, and retinal detachment. The visual prognosis is not as good as in ordinary age-related cataract due to the underlying ocular disease.
CATARACT ASSOCIATED WITH SYSTEMIC DISEASE
Bilateral cataracts occur in many systemic disorders including diabetes mellitus (Figure 8–8), hypocalcemia (of any cause), myotonic dystrophy, atopic dermatitis, galactosemia, and Down, Lowe (oculo-cerebro-renal), and Werner syndromes (see Chapters 15 and 18).
Figure 8–8. Punctate dot cataract. This type of cataract is sometimes seen as an ocular complication of diabetes mellitus. It may also be congenital.
DRUG-INDUCED CATARACT
Corticosteroids administered over a long period of time, either systemically (oral or inhaled) or in drop form, can cause lens opacities. Other drugs associated with cataract include phenothiazines and amiodarone (see Chapter 22).
406
CATARACT SURGERY
Cataract surgery is the most commonly performed surgical procedure worldwide. The generally preferred method in adults and older children preserves the posterior portion of the lens capsule and thus is known as extracapsular cataract extraction. An incision is made at the limbus or in the peripheral cornea, either superiorly or temporally. An opening is created in the anterior capsule (anterior capsulorhexis), and the nucleus and cortex of the lens are removed. (The femtosecond laser can be used for the initial incision, capsulorhexis, and other parts of the procedure, but its value for routine use is uncertain.) An intraocular lens is placed in the empty “capsular bag,” thus supported by the intact posterior capsule.
The technique of phacoemulsification is now the most common form of extracapsular cataract extraction in developed countries. It uses a handheld ultrasonic vibrator to disintegrate the hard nucleus such that the nuclear material and cortex can be aspirated through a small incision of approximately 2.5 to 3 mm. This same incision size is then adequate for insertion of foldable intraocular lenses. If a rigid intraocular lens is used, the wound needs to be extended to approximately 5 mm. In developing countries, particularly rural areas, the instruments for phacoemulsification are often not available. Manual sutureless small incision cataract surgery (MSICS) is based on the traditional nuclear expression form of extracapsular cataract extraction, in which the nucleus is removed intact, but using a small incision. The cortex is removed by manual aspiration. MSICS may be indicated for dense cataracts unsuitable for phacoemulsification.
The main intraoperative complication of extracapsular surgery is posterior capsular tear, for which the main predisposing factors include previous trauma, dense cataract, unstable lens, and small pupil, possibly leading to displacement of nuclear material into the vitreous (“dropped nucleus”) that generally necessitates complex vitreoretinal surgery. Postoperatively, there may be secondary opacification of the posterior capsule that requires discission using the neodymium:YAG laser (see Posterior Capsule Opacification later in the chapter).
Intraocular Lenses
There are many styles of intraocular lenses, but most designs consist of a central
407
optic and two legs (or haptics) to maintain the optic in position. The optimal intraocular lens position is within the capsular bag following an extracapsular procedure. This is associated with the lowest incidence of postoperative complications, such as pseudophakic bullous keratopathy, glaucoma, iris damage, hyphema, and lens decentration. The newest posterior chamber lenses are made of flexible materials such as silicone and acrylic polymers, allowing the lens implant to be folded and thus decreasing the required incision size. Lenses with multifocal optics can provide good vision for both near and distance without glasses. If there is inadvertent damage to the posterior capsule during extracapsular surgery, an intraocular lens can be placed in the anterior chamber or sutured to lie in the ciliary sulcus. Methods of calculating the correct dioptric power of an intraocular lens are discussed in Chapter 21. If an intraocular lens cannot be safely placed or is contraindicated, postoperative refractive correction generally requires a contact lens or aphakic spectacles.
Postoperative Care
The patient is usually ambulatory on the day of surgery but is advised to move cautiously and avoid straining or heavy lifting for about a month. The eye may be patched on the day of surgery. Protection at night by a metal shield is often suggested for several days after surgery. Topical postoperative antibiotics and anti-inflammatory drops are used for 4–6 weeks after surgery.
Complications of Adult Cataract Surgery
Cataract surgery in adults has a very low rate (2–5%) of complications that result in permanent impairment of vision. The most serious but rare complications are perioperative intraocular hemorrhage (< 0.5%) and postoperative intraocular infection (endophthalmitis, 0.1%), either of which can result in severe visual loss or removal of the eye. Suspicion of endophthalmitis requires vitreous tap for microscopy and culture and intravitreal injection of antibiotics (see Table 22–1). Vitrectomy is sometimes indicated (see Chapter 9). Other complications include retinal detachment, cystoid macular edema, glaucoma, corneal edema, and ptosis.
Posterior Capsule Opacification
About 10% of eyes require treatment for posterior capsule opacification
408
following uncomplicated phacoemulsification surgery (Figure 8–9).
Figure 8–9. Posterior capsule opacification (“after-cataract”).
Persistent lens epithelium on the capsule favors regeneration of lens fibers, giving the posterior capsule a “fish egg” appearance (Elschnig’s pearls). The proliferating epithelium may produce multiple layers, leading to opacification. These cells may also undergo myofibroblastic differentiation. Their contraction produces numerous tiny wrinkles in the posterior capsule, resulting in visual distortion.
The neodymium:YAG laser provides a noninvasive method of creating an optical window in the posterior capsule (see Chapter 23). Complications include a transient rise in intraocular pressure, damage to the intraocular lens, and rupture of the anterior hyaloid face with forward displacement of vitreous into the anterior chamber, potentially leading to rhegmatogenous retinal detachment or cystoid macular edema. The rise in intraocular pressure is usually detectable within 3 hours after treatment and resolves within a few days with treatment. Small pits or cracks may occur on the intraocular lens but usually have no effect on visual acuity.
Childhood Cataract Surgery
Cataract surgery in young children is often hindered by more difficult anterior capsulorhexis, as well as the frequent need to make an opening in the posterior capsule (posterior capsulorhexis) and to remove part of the vitreous (anterior vitrectomy) to reduce the incidence of posterior capsule opacification, which is much higher than after adult cataract surgery. The cataracts are less dense than in adults and can usually be removed by an irrigation–aspiration technique, without
409
the need for phacoemulsification.
Optical correction can consist of spectacles in older bilaterally aphakic children, but most childhood cataract operations are followed by contact lens correction, with adjustment of power as the refractive status of the eye changes with growth. Intraocular lenses are also used in some cases. They 184avoid the difficulties associated with contact lens wear, but there are difficulties calculating the appropriate power.
Prognosis
The visual prognosis for childhood cataract patients requiring surgery is not as good as that for patients with age-related cataract. The associated amblyopia and occasional anomalies of the optic nerve or retina limit the degree of useful vision that can be achieved in this group of patients. The prognosis for improvement of visual acuity is worst following surgery for unilateral congenital cataracts and best for incomplete bilateral congenital cataracts that are slowly progressive. Glaucoma is a common long-term complication.
DISLOCATED LENS (ECTOPIA LENTIS)
Partial or complete lens dislocation (subluxation) (Figure 8–10) may be hereditary or due to trauma.
Figure 8–10. Partially dislocated (subluxed) lens (right eye) with dilated pupils.
Hereditary Lens Dislocation
Hereditary lens dislocation is usually bilateral and may be an isolated familial anomaly or due to inherited connective tissue disorder such as homocystinuria,
410
Marfan syndrome, or Weill-Marchesani syndrome (see Chapter 15). The vision is blurred, particularly if the lens is dislocated out of the line of vision. If dislocation is partial, the edge of the lens and the zonular fibers holding it in place can be seen in the pupil. If the lens is completely dislocated into the vitreous, it may be visible with an ophthalmoscope.
A partially dislocated lens may be complicated by cataract formation. If that is the case, the cataract may have to be removed, but there is a significant risk of vitreous loss, predisposing to retinal detachment. If the lens is free in the vitreous, it may lead in later life to the development of glaucoma of a type that responds poorly to treatment. If dislocation is partial and the lens is clear, the visual prognosis is good.
Traumatic Lens Dislocation
Partial or complete traumatic lens dislocation may occur following a contusion injury such as a blow to the eye with a fist. If the dislocation is partial, there may be no visual symptoms; but if the lens is floating in the vitreous, the patient will have significantly blurred vision. Iridodonesis, a quivering of the iris when the patient moves the eye, is a common sign of lens dislocation and is due to the lack of lens support. This is present both in partially and in completely dislocated lenses but is more marked in the latter.
Uveitis and glaucoma are common complications of dislocated lens, particularly if dislocation is complete. If there are no complications, dislocated lenses are best left untreated. If uveitis or uncontrollable glaucoma occurs, lens extraction may need to be done despite the poor results possible from this operation. For completely dislocated lenses, the technique of choice is pars plana lensectomy or phacofragmentation, depending on the density of cataract. Some partially dislocated (subluxed) lenses are amenable to phacoemulsification with various adaptations, such as capsular tension rings or support hooks.
REFERENCES
Agarkar S et al: Incidence, management, and visual outcomes in pediatric endophthalmitis following cataract surgery by a single surgeon. J AAPOS 2016;20:415. [PMID: 27343836]
411
American Academy of Ophthalmology Cataract and Anterior Segment Panel: Preferred Practice Pattern Guidelines. Cataract in the adult eye. American Academy of Ophthalmology, 2011. Available at: http://www.aaojournal.org/content/preferred-practice-pattern
Ang GS et al: Manual small incision cataract surgery in a United Kingdom university teaching hospital setting. Int Ophthalmol 2010;30:23. [PMID: 19129974]
Behndig A et al: One million cataract surgeries: Swedish National Cataract Register 1992-2009. J Cataract Refract Surg 2011;37:1539. [PMID: 21782099]
Braga-Mele R et al: Multifocal intraocular lenses: Relative indications and contraindications for implantation. J Cataract Refract Surg 2014;40:313. [PMID: 24461503]
Celano M et al: Motor skills of children with unilateral visual impairment in the Infant Aphakia Treatment Study. Dev Med Child Neurol 2016;58:154. [PMID: 26084944]
Chang JR et al: Risk factors associated with incident cataracts and cataract surgery in the Age-related Eye Disease Study (AREDS): AREDS report number 32. Ophthalmology 2011;1180:2113. [PMID: 21684602]
Chu CJ et al: Risk factors and incidence of macular edema after cataract surgery: A database study of 81984 Eyes. Ophthalmology 2016;123:316. [PMID: 26681390]
Coleman AL. How big data informs us about cataract surgery: The LXXII Edward Jackson Memorial Lecture. Am J Ophthalmol 2015;160:1091. [PMID: 26432566]
Cooper K et al: The cost-effectiveness of second-eye cataract surgery in the UK. Age Ageing 2015;44:1026. [PMID: 26410365]
de Silva SR et al: Phacoemulsification with posterior chamber intraocular lens versus extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens for age-related cataract. Cochrane Database Syst Rev 2014;1:CD008812. [PMID: 24474622]
Findl O et al: Interventions for preventing posterior capsule opacification. Cochrane Database Syst Rev 2010;2:CD003738. [PMID: 20166069]
Freedman SF et al: Glaucoma-related adverse events in the first 5 years after
412
unilateral cataract removal in the Infant Aphakia Treatment Study. JAMA Ophthalmol 2015;133:907. [PMID: 25996491]
Garcia-Gutierrez S et al: Impact of clinical and patient-reported outcomes on patient satisfaction with cataract extraction. Health Expect 2014;17:765. [PMID: 22784407]
Glaser TS et al: The association of dietary lutein plus zeaxanthin and B vitamins with cataracts in the Age-Related Eye Disease Study: AREDS Report No. 37. Ophthalmology 2015;122:1471. [PMID: 25972257]
González N et al: Factors affecting cataract surgery complications and their effect on the postoperative outcome. Can J Ophthalmol 2014;49:72. [PMID: 24513361]
Grewal DS et al: Femtosecond laser-assisted cataract surgery-current status and future directions. Surv Ophthalmol 2016;61:103. [PMID: 26409902]
Hartmann EE et al: Stereopsis results at 4.5 years of age in the Infant Aphakia Treatment Study. Am J Ophthalmol 2015;159:64. [PMID: 25261241]
Herrinton LJ et al: Comparative effectiveness of antibiotic prophylaxis in cataract surgery. Ophthalmology 2016;123:287. [PMID: 26459998]
Hoffman RS et al: Management of the subluxated crystalline lens. J Cataract Refract Surg 2013;39:1904. [PMID: 24286841]
Hoffman RS et al: Cataract surgery in the small eye. J Cataract Refract Surg 2015;41:2565. [PMID: 26703508]
Infant Aphakia Treatment Study Group: The infant aphakia treatment study: Design and clinical measures at enrolment. Arch Ophthalmol 2010;128:21. [PMID: 20065212]
Jabbarvand M et al: Endophthalmitis occurring after cataract surgery: Outcomes of more than 480,000 cataract surgeries, epidemiologic features, and risk factors. Ophthalmology 2016;123:295. [PMID: 26704882]
Javitt JC: Intracameral antibiotics reduce the risk of endophthalmitis after cataract surgery: Does the preponderance of the evidence mandate a global change in practice? Ophthalmology 2016;123:226. [PMID: 26802702]
Kruger SJ et al: Cost of intraocular lens versus contact lens treatment after unilateral congenital cataract surgery in the Infant Aphakia Treatment Study at age 5 years. Ophthalmology 2015;122:288. [PMID: 25439604]
413
Lee CM et al: The global state of cataract blindness. Curr Opin Ophthalmol 2017;28:98. [PMID: 27820750]
Lim JC et al: Tools to fight the cataract epidemic: A review of experimental animal models that mimic age related nuclear cataract. Exp Eye Res 2016;145:432. [PMID: 26391448]
Lin AA et al: Update on pediatric cataract surgery and intraocular lens implantation. Curr Opin Ophthalmol 2010;21:55. [PMID: 19855277]
Lundström M et al: Decreasing rate of capsule complications in cataract surgery: Eight-year study of incidence, risk factors, and data validity by the Swedish National Cataract Register. J Cataract Refract Surg 2011;37:1762. [PMID: 21820852]
Lundström M et al: Risk factors for endophthalmitis after cataract surgery: Predictors for causative organisms and visual outcomes. J Cataract Refract Surg 2015;41:2410. [PMID: 26703490]
Malik A et al: Local anesthesia for cataract surgery. J Cataract Refract Surg 2010;36:133. [PMID: 20117717]
Mesnard C et al: Endophthalmitis after cataract surgery despite intracameral antibiotic prophylaxis with licensed cefuroxime. J Cataract Refract Surg 2016;42:1318. [PMID: 27697250]
Morrison DG et al: Corneal changes in children after unilateral cataract surgery in the Infant Aphakia Treatment Study. Ophthalmology 2015;122:2186. [PMID: 26271843]
Nagy ZZ et al: Femtosecond laser cataract surgery. Eye Vis (Lond) 2015;2:11. [PMID: 26605364]
Palagyi A et al: While we waited: Incidence and predictors of falls in older adults with cataract. Invest Ophthalmol Vis Sci 2016;57:6003. [PMID: 27820872]
Plager DA et al: Complications in the first 5 years following cataract surgery in infants with and without intraocular lens implantation in the Infant Aphakia Treatment Study. Am J Ophthalmol 2014;158:892. [PMID: 25077835]
Reilly MA: A quantitative geometric mechanics lens model: Insights into the mechanisms of accommodation and presbyopia. Vision Res 2014;103:20. [PMID: 25130408]
414
Repka MX et al: Cataract surgery in children from birth to less than 13 years of age: Baseline characteristics of the cohort. Ophthalmology 2016;123:2462. [PMID: 27769584]
Riaz Y et al: Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus phacoemulsification with posterior chamber intraocular lens for age-related cataract. Cochrane Database Syst Rev 2013;10:CD008813. [PMID: 24114262]
Sachdeva V et al: Validation of guidelines for undercorrection of intra-ocular lens (IOL) power in children. Am J Ophthalmol 2017;174:17. [PMID: 27818207]
Sadiq MA et al: Genetics of ectopia lentis. Semin Ophthalmol 2013;28:313. [PMID: 24138040]
Schmier JK et al: An updated estimate of costs of endophthalmitis following cataract surgery among Medicare patients: 2010-2014. Clin Ophthalmol 2016;10:21217. [PMID: 27822008]
Shah M et al: Controversies in traumatic cataract classification and management: A review. Can J Ophthalmol 2013;48:251. [PMID: 23931462]
Sheppard JD. Topical bromfenac for prevention and treatment of cystoid macular edema following cataract surgery: A review. Clin Ophthalmol 2016;10:2099. [PMID: 27822006]
Strenk SA et al: Magnetic resonance imaging of the anterioposterior position and thickness of the aging, accommodating, phakic, and pseudophakic ciliary muscle. J Cataract Refract Surg 2010;36:235. [PMID: 20152603]
Struck MC. Long-term results of pediatric cataract surgery and primary intraocular lens implantation from 7 to 22 months of life. JAMA Ophthalmol 2015;133:1180. [PMID: 26111188]
Thompson J et al: Cataracts. Prim Care 2015;42:409. [PMID: 26319346]
Venkatesh R et al: Carbon footprint and cost-effectiveness of cataract surgery. Curr Opin Ophthalmol 2016;27:82. [PMID: 26569528]
415