Cataract Surgery

Article Author:
Majid Moshirfar
Article Author:
Dallin Milner
Article Editor:
Bhupendra Patel
Updated:
6/26/2020 12:07:57 AM
PubMed Link:
Cataract Surgery

Introduction

Cataracts are the world’s leading cause of remediable blindness. While some cataracts, may be congenital, secondary to trauma, or drug-induced, most cataracts are age-related. Age-related cataracts are due to the opacification of the lens. The crystalline lens is a biconvex structure that focuses light on the retina. It is transparent with a diameter of 10 mm and an axial length of around 4 mm. The lens consists of fibers that are derived from lens epithelium, a thin surrounding capsule, and zonular fibers that allow for accommodation in conjunction with the ciliary body. With age, the lens stiffens, leading to farsightedness known as presbyopia. While one of the main functions of the lens is to focus light, it is not a passive optical element. In order to maintain transparency, the lens has a microcirculation pathway driven by sodium channels that deliver nutrients to deeper fibers through extracellular inward flow. Intracellular outward flow is maintained through gap junctions and is used to remove waste. The lens also serves as a UV filter that protects the retina. Finally, the lens acts as an oxygen sink with some of the highest concentrations of the antioxidant glutathione (GSH) in the body. Glutathione scavenges reactive oxygen species, is a co-factor for repair enzymes, and is thought to be released into the aqueous humor to be used by the avascular tissues such as the cornea and trabecular network. With age, oxidative damage can accumulate, causing an opacification of the lens.[1][2]

Regardless of the etiology, the treatment is cataract surgery when the visual function is affected. Cataract has secondary complications such as glaucoma and uveitis when it is allowed to progress on its natural course. With newer and well-developed techniques, cataract surgery is one of the most successful clinical managements in medicine with direct improvements in visual acuity as well as large improvements in activities of daily living and decreased mortality. While as many as 95% of patients will have improved visual acuity, cataract surgery does have complications. The most common include posterior capsule opacification and cystoid macular edema. Rare but serious complications include endophthalmitis and retinal detachment.

Cataracts are one of the most common ophthalmic pathologies characterized by the opacification of the lens. In 2013, the United States had more than 22 million people who had cataracts.[3] In 2020, that number is expected to reach 30.1 million.[4] Incidence increases with age; 43-year-old to 54-year-old patients have an incidence of 8.3%, while patients over 75 have an incidence as high as 70.5%. Women are slightly more affected, with an average incidence of 26% and men 22.6%.[5] In 2015, 3.7 million cataract surgeries were performed in the United States[4] with data suggesting that the incidence of cataract surgery will continue to increase.[3]

Anatomy and Physiology

A majority of adult cataracts are age-related with other etiologies suspected to be due to ultra-violet (UV) light exposure, smoking, diabetes, corticosteroid exposure, and other oxidizing drugs. Pediatric cataracts can be hereditary, idiopathic, or part of multisystem syndromes, metabolic disorders, or maternal infection.[6] Age-related cataracts are thought to be due to oxidative damage to the lens[7] and are divided anatomically into nuclear, cortical, and posterior subcapsular. Nuclear cataracts are the most common, with an incidence of 13.1%.[5] With age, the lens adds new fibers that compress the nucleus, eventually leading to nuclear sclerosis.[6] While cortical cataracts are the second most common (incidence of 8.2%), they are the most likely to require surgical intervention.[5][8] Typically, they present on examination as opacities within the cortex known as cortical spokes.[6] Posterior lens opacity is the least common (incidence of 3.4%)[5] and is due to opacification in the posterior cortex. 

Around half of congenital cataracts are genetic, and most genes are involved in lens development, including a, b, and g crystallin as well as lens cytoskeletal protein. Other causes include metabolic disorders, maternal infection, trauma, and toxic effects. Corticosteroids are associated with posterior subcapsular cataracts. Other medications that can also cause cataracts include busulfan, amiodarone, and phenothiazine.[7] Cataracts caused by trauma require special attention as the damage is rarely limited to the lens alone, with nearly half of injuries damaging the posterior segment.[9]

Indications

The type of cataract determines the initial presentation. Nuclear cataracts can present with decreased distance visual acuity, decreased ability to recognize faces and discriminate colors. Patients with nuclear cataracts can have good levels of Snellen acuity. Cortical cataracts may cause glare, difficulty reading, and light sensitivity. Patients with posterior subcapsular cataracts can present paradoxically, with poor vision in good lighting and improved vision in dim lighting. They can also have difficulty with driving during the day and reading.[10] If left untreated, hyper-mature senile cataracts can develop. Complications include uveitis, glaucoma, dislocation of the lens, which may lead to severely impaired vision or even complete loss of visual acuity.[11] Signs and symptoms of congenital defects depend on the stage of presentation, but white cataracts can be recognized by parents and pediatricians can notice the asymmetry of the red reflex, as well as signs of poor vision, i.e., failure to look at light sources, no tracking, and failure to make eye contact.

According to the American Academy of Ophthalmology, the goal of diagnosis is to determine if visual complaints are due to the presence of cataracts, if a cataract is present, to understand the clinical significance, and to rule out other conditions that cause visual impairment.

The evaluation includes:

  • A comprehensive history
  • Visual acuity with correction
  • Glare testing
  • Assessing pupillary function
  • Examining ocular alignment
  • External examination
  • Measuring intraocular pressure (IOP)
  • Slit-lamp examination of the anterior segment, lens, vitreous humor
  • Ophthalmoscopy of the macula, retina, and optic nerve
  • Other tests that may be considered include, optical coherence tomography (OCT), to evaluate retinal or anterior segment disorder. B-scan ultrasound can be done if cataract density prevents visualization of the posterior segment.

Differential Diagnosis

  1. Glaucoma
  2. Diabetic Retinopathy
  3. Age-related macular degeneration

Glaucoma is a group of conditions that are characterized by progressive damage to the optic nerve. Although it is often associated with increased ocular pressure, the optic disc can be damaged with normal IOP. Initially, the patient is asymptomatic but eventually begins to lose both peripheral and central vision. Vision loss is permanent. The incidence is highest among black Americans.[12]

Diabetic Retinopathy: Presents in patients with both type 1 and type 2 diabetes. Patients typically present complaining of fluctuating vision, floaters, photopsia, and visual loss. On exam, microaneurysms, intraretinal hemorrhages, and hard exudates in the non-proliferative type. In the proliferative type, fibrous proliferation, new blood vessels, and macular edema can be seen.[13]

Age-related Macular Degeneration (AMD): Dry AMD presents with worsening vision and more dependence on brighter lights or magnifying lenses. Scotomas, difficulty reading, or driving might be noticed.[14] Drusen can be seen on examination. Wet AMD will present with central visual disturbances that are clinically tested with line distortion known as an Amsler grid.[15]

Cataracts may occur in patients with glaucoma, diabetic retinopathy, or age-related macular degeneration. Comorbidities should be managed appropriately. 

Indications for surgery vary by country but generally include poor visual acuity, visual difficulties, or both due to cataracts.[16] Formal assessments that can be used to assess for cataract surgery include the Catquest-9Sf questionnaire or the Visual Functioning Index-14.[7]

Contraindications

Contraindications to surgery include cataracts without visual impairment or medical/ophthalmic conditions that do not allow for safe surgical outcomes.  

Equipment

Intraocular Lens (IOL): Before intraocular lenses were used, cataractous lenses were simply removed, and the patients would then need high-power spectacles or contact lenses to attain optimal visual acuity.[17] Originally, a clear lens of polymethyl methacrylate was placed in the posterior chamber.[18] The lens was rigid and worked well with the ECCE technique. However, the small incisions of newer techniques like phacoemulsification necessitated foldable lenses of acrylic and silicone, which are the materials used today.[19] Toric IOLs are used to correct astigmatism and also reduce the need for glasses.[7] Once in the capsular bag, IOLs must be fixed, which is accomplished by several haptic designs: plate-type, one-piece, and three-piece lenses. Plate-type is molded from the same material as the lens and appears as a rectangular shape. Plate-type haptics can be inserted by a small incision, but have an increased risk of dislocation.[20] One-piece designs are also made from the same material as the lens but have open-loop haptic arms. These are associated with more posterior capsular opacification but fewer dysphotopsias.[21] Three-piece designs consist of the lens and two open loops, which can be made out of PMMA, polypropylene, or polyamide. Three-piece IOLs are equal in visual outcomes to single-piece IOLs.[22][23][24]

Intraocular lenses (IOL) can be monofocal, multifocal, and toric. Monofocal aspheric IOLs correct for power lost by the removal of the natural lens. They are the most commonly implanted due to low cost. Since the IOL corrects only one focal distance, glasses or contact lenses may be necessary for either distance or near vision. Note that the patient has an option to choose monovision as an outcome, where one eye has an IOL for distance vision while the other eye is for near vision. Multifocal IOLs are used to correct refractive vision errors to decrease the need for glasses. Of the multifocal lenses, bifocal diffractive lenses provide better near visual acuity than monofocal lenses. Trifocal diffractive lenses are intended to improve intermediate vision; although, current evidence of their effectiveness is inconclusive.[25] Another multifocal lens, extended depth of focus, was invented to focus light on a continuous plane which would eliminate halo effects and provide improved whole range vision.[26] Another type of lens, known as a light adjustable lens, when hit with UV light, will change shape and produce a different IOL power.[27] Accommodative IOLs are designed to move with contractions of the ciliary body.[28] Once a lens is in place, a new technique using a femtosecond laser is being developed as a way to adjust the power.[29]

Before surgery, ophthalmologists take into account patient anatomy and other factors to determine the needed power of the intraocular lens.[30] Several instruments are used to calculate IOL power. These include measuring corneal power with computerized videokeratography, axial length, A-constant, and gain.[31] Theoretical formulas are then used to calculate power. The largest contributor of error is the estimated lens position (ELP). Five generations of formulas have been developed to more accurately predict the lens position. The first generation formula, SRK, used a constant value for ELP; the second generation, Hoffer, formula used axial length to predict ELP; third-generation formulas (Holladay, SRK/T, and Hoffer Q) predict ELP using axial length and anterior corneal curvature; fourth and fifth-generation formulas use third-generation measurements and include anterior chamber depth.[32]

Preparation

The ophthalmologic evaluation includes a thorough ophthalmic history, with a focus on visual acuity as well as comorbidities, and slit-lamp examination. Several measurements of the eye are then taken, including the anterior chamber depth, to determine intraocular lens refraction.[33] While thorough medical history should be taken before surgery, routine systemic preoperative tests do not need to be ordered.[34] Some institutions may require clearance from the primary care physician when patients have underlying systemic diseases.[35] Due to the low risk of bleeding, antithrombotic drugs can be continued.[36] The use of alpha-1-antagonists should be noted due to the risk of intraoperative floppy iris syndrome.[37]

Technique

Anesthesia: Historically, general anesthesia and retrobulbar blocks were used for intracapsular cataract surgery. However, with the advent of phacoemulsification and small incision surgeries, clinicians have since moved to local and topical anesthesia.[38][39]

Intracapsular Cataract Extraction (ICCE): A technique that was discovered in the 18th century that involves removing the entire lens and capsule through a single incision. Due to lower complication rates with improved surgical techniques, ICCE is rarely performed.[40]

Manual Extracapsular Cataract Extraction: In this technique, the lens is extracted through an incision, and the intraocular lens (IOL) is then inserted. The incision is large, usually 9 mm to 13 mm, to accommodate extraction, and sutures are necessary. However, there is an increased risk of posterior capsule opacity, age-related macular degeneration, and corneal edema when compared to phacoemulsification.[41] However, lower costs led to continued use of this technique throughout the world. Today, an adaptation of ECCE, manual small incision cataract surgery, has comparable outcomes to phacoemulsification.[42]

Manual Small-incision Cataract Surgery (MSICS): Instead of a large incision, MSICS uses a scleral tunnel that can self-seal. The much smaller external incision (6.5 mm to 7 mm) with a larger internal incision (9 mm to 11 mm) leads to a natural seal. The lens is then delivered through the V-shaped incision, and an IOL is inserted.[43] A Cochrane review published in 2013 found that while phacoemulsification may be superior in early postoperative uncorrected visual acuity, MSICS and phacoemulsification have comparable outcomes for long-term best-corrected visual acuity as well as postoperative complications. The reviewers did find that MSICS was significantly cheaper (70 vs. 15 USD).[44]

Phacoemulsification: This is a technique developed by Charles Kelman in 1967. It involves making a small incision of 2 mm to 3 mm and the insertion of an ultrasonic probe. The probe is then able to emulsify and aspirate the lens.[45] The smaller incision allowed for a self-sealing wound. Foldable lenses were developed to fit into the small incision.[19] Advantages over ECCE include improved visual acuity, decreased risk of astigmatism, and decreased postoperative inflammation. Suture-related complications are also avoided.[42][46](Videos 1 & 2)

Femtosecond Assisted Laser Cataract Surgery (FLACS): This technique, developed in 2008, uses a laser to microscopically dissect tissue, greatly reducing the risk of collateral damage.[47] The laser, originally used in LASIK, is used to create the corneal incision and perform the capsulotomy and initial lens fragmentation. This has decreased the need for manual incisions as well as reducing the time and energy of phacoemulsification.[48] However, due to increased cost over phacoemulsification, with marginal benefit, many clinicians question the current practicality of FLACS.[49]

Refractive Lens Exchange (RLE): RLE uses cataract surgery techniques to replace the lens of a patient with a high refractive error when laser ablative surgery is not possible or in patients with impending cataract. In addition to cataract procedural risks, these patients are at a higher risk of retinal detachment due to cumulative risk over time. Patients with moderate to severe myopia are at even more of an increased risk for retinal detachment. Patients with severe hyperopia are more likely to develop choroidal edema. Additionally, patients are more likely to develop early age-related macular degeneration, which is thought to be due to loss of free-radical scavenging properties with the removal of the lens.[27] Patients are also more likely to develop open-angle glaucoma believed to be due to damage to the trabecular network from increased oxygen levels.[2]

Postoperative Care: Typically, patients are prescribed topical antibiotics, corticosteroids, or non-steroidal anti-inflammatory drops for 1 to 4 weeks postoperatively. Patients are counseled to follow-up the day after surgery, at 1 week, 1 month, and then 3 months postoperatively.[7]

Complications

Complications can be divided within three time periods, i.e., intraoperative, early postoperative, and late postoperative. 

Intraoperative Complications: The most common include posterior capsule rupture (0.5% to 5.2%), intraoperative iris floppy syndrome (0.5% to 2.0%), or iris or ciliary body injury (0.6%-1.2%).[7] Posterior capsule rupture can lead to retained lens fragments, corneal edema, and cystoid macular edema.[50] Posterior capsule rupture leads to a six-fold increased risk in endophthalmitis[51] and increases the risk of retinal detachment as high 19 times.[52]

Early Postoperative Complications: Some of the more common complications include transient elevated intraocular pressure, cornea edema, toxic anterior segment syndrome, and endophthalmitis.[7] Even in glaucomatous eyes, after one-year, all patients will have IOP control, with some even having a decreased need for medication.[53]

Endophthalmitis, while rare due to intracameral antibiotics, is one of the most severe complications post-cataract surgery. The increased risk of endophthalmitis is reported in patients with Diabetes mellitus, advanced age (over 80), vitreous communication, and large incision ECCE.[54] Patients typically present within two weeks after surgery with decreased visual acuity, red-eye, and pain.[55] Hypopyon is commonly present, around 80% of the time.[56] Common organisms include coagulase-negative staphylococci and Staphylococcus aureus, which account for 80% of infections.[55] Management includes vitreous humor tap and injection of broad-spectrum antibiotics. Typically, vancomycin 1 mg/0.1 mL with either amikacin 0.4 mg/0.1 mL or ceftazidime 2.25 mg/0.1 mL.[55] Even with treatment, outcomes can be severe, including permanent decreased visual acuity to no light perception, with the prognosis being highly dependent on the microbiologic etiology.[56]

Late Postoperative Complications: Common complications that present later include posterior capsule opacification (0.3% to 28.4%), clinical cystoid macular edema, and retinal detachment (0.1% to 1.3%).[7]

Posterior capsule opacification is the most common late complication. It can occur as many as 1 in 5 eyes in the three years following surgery with even higher rates in the following years.[57] Posterior capsule opacification is due to residual lens epithelial cells on the anterior capsule that then migrate to the posterior capsule after cataract surgery, decreasing visual acuity.[58] Patients can also present with blurred vision as well as complaints of glare. Treatment involves using a YAG laser to perform the capsulotomy. Complications from this treatment include damaging the IOL, transient pressure elevation, cystoid macular edema, and retinal detachment.[59]

Cystoid macular edema is due to leaky perifoveal capillaries secondary to the release of proinflammatory cytokines.[60] Common complaints include decreased vision, central loss of vision, or distorted vision.[61] Treatment includes topical corticosteroids and nonsteroidal anti-inflammatory drug (NSAID) eye-drops.[62]

Increased risk of retinal detachment is reported in patients who are younger and male. Anatomical risk factors include axial length greater than 26 mm and posterior vitreous detachment.[63] Symptoms typically include flashing lights, floaters, as well as peripheral vision loss with progression to complete vision loss. Retinal detachments are usually diagnosed with direct or indirect ophthalmoscopy, where edematous retinal folds with loss of transparency can be seen. On slit lamp, pigment cells present in the anterior vitreous is a sensitive finding. Depending on the presentation, treatment can include laser-pexy, pneumatic retinopexy, pars plana vitrectomy, or scleral buckle.[4]

Common complaints after surgery: even though cataract surgery greatly improves vision and quality of life, patients may continue to have subjective visual complaints. Commonly, they will include seeing shadows, halos, glare, starburst patterns around lights, and hazy vision. These symptoms are known as dysphotopsias and can be divided into positive and negative symptoms. Positive symptoms involve starbursts and haloes, while negative symptoms include shadows or dark areas. These symptoms can be caused by acrylic IOLs, and management for intolerable symptoms can include an exchange with a PMMA or silicone IOL. Risk factors for negative symptoms include small pupils, short distance to IOL, functional nasal retina, and an IOL with a high index of refraction. Treatments can include repositioning the IOL, secondary placement of IOL, and Nd:YAG laser anterior capsulotomy.[64]

Clinical Significance

Cataract surgery is a safe and highly effective treatment. As many as 95% of patients will have a best-corrected visual acuity of 20/40 after surgery.[65] Patients report improvement in mental and emotional well-being, improved social interactions, as well as improvements in reading, watching television, and recognizing people.[66] Patients who undergo cataract surgery are also less likely to be involved in traffic crashes.[67] There is an overall mortality benefit to patients who undergo cataract surgery.[68] Finally, there is an economic benefit to cataract surgery with an ROI of 833% due to high costs associated with poor vision such as depression, injury, hospital admissions, necessary care-takers, and decreased employment.[69]

Enhancing Healthcare Team Outcomes

Primary care physicians and providers (PCP) have an important role in identifying patients with decreased visual loss due to cataracts. With patient complaints of decline in visual functions such as difficulty reading, difficulty recognizing faces, or smaller objects such as golf balls, glare, or worsening vision at night, a PCP should suspect cataracts and do a thorough history and physical exam. If cataracts are visualized, or the PCP has a high degree of suspicion, they should refer to ophthalmology. Within surgery, ophthalmologists rely on anesthesiology, nurses, as well as scrub techs. While ophthalmology follows postoperatively for up to one year, some complications, like posterior capsule opacification, can present up to 3 years later. With these later complications, ophthalmologists rely on primary care teams to recognize these later term complications as patients might present in their clinic.



  • Video by Prof. Majid Moshirfar MD, Dr. Trey Fanning, Dr. Orry Birdsong, Dr. Aaron T. Gomez. Contributed by Prof. Bhupendra C. K. Patel MD, FRCS

  • Video by Dr. Michael J. Bradley MD and Prof. Majid Moshirfar MD. Contributed by Prof. Bhupendra C. K. Patel MD, FRCS

References

[1] Hejtmancik JF,Riazuddin SA,McGreal R,Liu W,Cvekl A,Shiels A, Lens Biology and Biochemistry. Progress in molecular biology and translational science. 2015;     [PubMed PMID: 26310155]
[2] Lim JC,Umapathy A,Grey AC,Vaghefi E,Donaldson PJ, Novel roles for the lens in preserving overall ocular health. Experimental eye research. 2017 Mar;     [PubMed PMID: 27282996]
[3] Gollogly HE,Hodge DO,St Sauver JL,Erie JC, Increasing incidence of cataract surgery: population-based study. Journal of cataract and refractive surgery. 2013 Sep;     [PubMed PMID: 23820302]
[4] Ianchulev T,Litoff D,Ellinger D,Stiverson K,Packer M, Office-Based Cataract Surgery: Population Health Outcomes Study of More than 21 000 Cases in the United States. Ophthalmology. 2016 Apr;     [PubMed PMID: 26804760]
[5] Klein BE,Klein R,Lee KE, Incidence of age-related cataract: the Beaver Dam Eye Study. Archives of ophthalmology (Chicago, Ill. : 1960). 1998 Feb;     [PubMed PMID: 9488275]
[6] Asbell PA,Dualan I,Mindel J,Brocks D,Ahmad M,Epstein S, Age-related cataract. Lancet (London, England). 2005 Feb 12-18;     [PubMed PMID: 15708105]
[7] Liu YC,Wilkins M,Kim T,Malyugin B,Mehta JS, Cataracts. Lancet (London, England). 2017 Aug 5;     [PubMed PMID: 28242111]
[8] Vrensen GF, Early cortical lens opacities: a short overview. Acta ophthalmologica. 2009 Sep;     [PubMed PMID: 19719805]
[9] Kuhn F, Traumatic cataract: what, when, how. Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. 2010 Sep;     [PubMed PMID: 20428883]
[10] Day AC,Gore DM,Bunce C,Evans JR, Laser-assisted cataract surgery versus standard ultrasound phacoemulsification cataract surgery. The Cochrane database of systematic reviews. 2016 Jul 8;     [PubMed PMID: 27387849]
[11] Sahay P,Goel S,Maharana PK,Sharma N,Titiyal JS, Sequelae of neglected hypermature senile cataract. Indian journal of ophthalmology. 2019 Oct;     [PubMed PMID: 31546522]
[12] Pelletier AL,Rojas-Roldan L,Coffin J, Vision Loss in Older Adults. American family physician. 2016 Aug 1;     [PubMed PMID: 27479624]
[13] Moreno A,Lozano M,Salinas P, Diabetic retinopathy. Nutricion hospitalaria. 2013 Mar;     [PubMed PMID: 23834047]
[14] Quillen DA, Common causes of vision loss in elderly patients. American family physician. 1999 Jul;     [PubMed PMID: 10414631]
[15] Jager RD,Mieler WF,Miller JW, Age-related macular degeneration. The New England journal of medicine. 2008 Jun 12;     [PubMed PMID: 18550876]
[16] Lundström M,Goh PP,Henry Y,Salowi MA,Barry P,Manning S,Rosen P,Stenevi U, The changing pattern of cataract surgery indications: a 5-year study of 2 cataract surgery databases. Ophthalmology. 2015 Jan;     [PubMed PMID: 25234011]
[17] Davis G, The Evolution of Cataract Surgery. Missouri medicine. 2016 Jan-Feb;     [PubMed PMID: 27039493]
[18] Apple DJ,Mamalis N,Loftfield K,Googe JM,Novak LC,Kavka-Van Norman D,Brady SE,Olson RJ, Complications of intraocular lenses. A historical and histopathological review. Survey of ophthalmology. 1984 Jul-Aug;     [PubMed PMID: 6390763]
[19] Kohnen T,Lambert RJ,Koch DD, Incision sizes for foldable intraocular lenses. Ophthalmology. 1997 Aug;     [PubMed PMID: 9261314]
[20] Doan KT,Olson RJ,Mamalis N, Survey of intraocular lens material and design. Current opinion in ophthalmology. 2002 Feb;     [PubMed PMID: 11807385]
[21] Chang DF, Single versus three piece acrylic IOLs. The British journal of ophthalmology. 2004 Jun;     [PubMed PMID: 15148199]
[22] Chehade M,Elder MJ, Intraocular lens materials and styles: a review. Australian and New Zealand journal of ophthalmology. 1997 Nov;     [PubMed PMID: 9395827]
[23] Kim SY,Yang JW,Lee YC,Kim SY, Effect of haptic material and number of intraocular lens on anterior capsule contraction after cataract surgery. Korean journal of ophthalmology : KJO. 2013 Feb;     [PubMed PMID: 23372373]
[24] Sato T,Shibata S,Yoshida M,Hayashi K, Short-term Dynamics after Single- and Three-piece Acrylic Intraocular Lens Implantation: A Swept-source Anterior Segment Optical Coherence Tomography Study. Scientific reports. 2018 Jul 6;     [PubMed PMID: 29980770]
[25] Yoon CH,Shin IS,Kim MK, Trifocal versus Bifocal Diffractive Intraocular Lens Implantation after Cataract Surgery or Refractive Lens Exchange: a Meta-analysis. Journal of Korean medical science. 2018 Oct 29;     [PubMed PMID: 30369857]
[26] Akella SS,Juthani VV, Extended depth of focus intraocular lenses for presbyopia. Current opinion in ophthalmology. 2018 Jul;     [PubMed PMID: 29697436]
[27] Alio JL,Grzybowski A,El Aswad A,Romaniuk D, Refractive lens exchange. Survey of ophthalmology. 2014 Nov-Dec;     [PubMed PMID: 25127929]
[28] Zvorničanin J,Zvorničanin E, Premium intraocular lenses: The past, present and future. Journal of current ophthalmology. 2018 Dec;     [PubMed PMID: 30555960]
[29] Nguyen J,Werner L,Ludlow J,Aliancy J,Ha L,Masino B,Enright S,Alley RK,Sahler R, Intraocular lens power adjustment by a femtosecond laser: In vitro evaluation of power change, modulation transfer function, light transmission, and light scattering in a blue light-filtering lens. Journal of cataract and refractive surgery. 2018 Feb;     [PubMed PMID: 29525614]
[30] Holladay JT,Prager TC,Chandler TY,Musgrove KH,Lewis JW,Ruiz RS, A three-part system for refining intraocular lens power calculations. Journal of cataract and refractive surgery. 1988 Jan;     [PubMed PMID: 3339543]
[31] Sahin A,Hamrah P, Clinically relevant biometry. Current opinion in ophthalmology. 2012 Jan;     [PubMed PMID: 22081032]
[32] Martinez-Enriquez E,Pérez-Merino P,Durán-Poveda S,Jiménez-Alfaro I,Marcos S, Estimation of intraocular lens position from full crystalline lens geometry: towards a new generation of intraocular lens power calculation formulas. Scientific reports. 2018 Jun 29;     [PubMed PMID: 29959385]
[33] See CW,Iftikhar M,Woreta FA, Preoperative evaluation for cataract surgery. Current opinion in ophthalmology. 2019 Jan;     [PubMed PMID: 30489358]
[34] Schein OD,Katz J,Bass EB,Tielsch JM,Lubomski LH,Feldman MA,Petty BG,Steinberg EP, The value of routine preoperative medical testing before cataract surgery. Study of Medical Testing for Cataract Surgery. The New England journal of medicine. 2000 Jan 20;     [PubMed PMID: 10639542]
[35] Keay L,Lindsley K,Tielsch J,Katz J,Schein O, Routine preoperative medical testing for cataract surgery. The Cochrane database of systematic reviews. 2019 Jan 8;     [PubMed PMID: 30616299]
[36] Kong KL,Khan J, Ophthalmic patients on antithrombotic drugs: a review and guide to perioperative management. The British journal of ophthalmology. 2015 Aug;     [PubMed PMID: 25425711]
[37] Thompson J,Lakhani N, Cataracts. Primary care. 2015 Sep;     [PubMed PMID: 26319346]
[38] Fichman RA, Use of topical anesthesia alone in cataract surgery. Journal of cataract and refractive surgery. 1996 Jun;     [PubMed PMID: 8784636]
[39] Nouvellon E,Cuvillon P,Ripart J,Viel EJ, Anaesthesia for cataract surgery. Drugs     [PubMed PMID: 20030430]
[40] Sugihara K,Tanito M,Takai Y,Ohira A, Causes of intracapsular cataract extraction, explantation of intraocular lenses and suture scleral fixation of intraocular lenses in the modern era. Acta ophthalmologica. 2018 Mar;     [PubMed PMID: 29098792]
[41] Minassian DC,Rosen P,Dart JK,Reidy A,Desai P,Sidhu M,Kaushal S,Wingate N, Extracapsular cataract extraction compared with small incision surgery by phacoemulsification: a randomised trial. The British journal of ophthalmology. 2001 Jul;     [PubMed PMID: 11423457]
[42] Jaggernath J,Gogate P,Moodley V,Naidoo KS, Comparison of cataract surgery techniques: safety, efficacy, and cost-effectiveness. European journal of ophthalmology. 2014 Jul-Aug;     [PubMed PMID: 24366765]
[43] Bernhisel A,Pettey J, Manual small incision cataract surgery. Current opinion in ophthalmology. 2020 Jan;     [PubMed PMID: 31770166]
[44] Riaz Y,de Silva SR,Evans JR, Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus phacoemulsification with posterior chamber intraocular lens for age-related cataract. The Cochrane database of systematic reviews. 2013 Oct 10;     [PubMed PMID: 24114262]
[45] Kelman CD, Phaco-Emulsification and Aspiration: A New Technique of Cataract Removal: A Preliminary Report. American journal of ophthalmology. 2018 Jul;     [PubMed PMID: 29929630]
[46] Oshika T,Yoshimura K,Miyata N, Postsurgical inflammation after phacoemulsification and extracapsular extraction with soft or conventional intraocular lens implantation. Journal of cataract and refractive surgery. 1992 Jul;     [PubMed PMID: 1501087]
[47] Donaldson KE,Braga-Mele R,Cabot F,Davidson R,Dhaliwal DK,Hamilton R,Jackson M,Patterson L,Stonecipher K,Yoo SH, Femtosecond laser-assisted cataract surgery. Journal of cataract and refractive surgery. 2013 Nov;     [PubMed PMID: 24160384]
[48] Roberts HW,Day AC,O'Brart DP, Femtosecond laser-assisted cataract surgery: A review. European journal of ophthalmology. 2020 May;     [PubMed PMID: 31801354]
[49] Abell RG,Vote BJ, Cost-effectiveness of femtosecond laser-assisted cataract surgery versus phacoemulsification cataract surgery. Ophthalmology. 2014 Jan;     [PubMed PMID: 24120324]
[50] Hong AR,Sheybani A,Huang AJ, Intraoperative management of posterior capsular rupture. Current opinion in ophthalmology. 2015 Jan;     [PubMed PMID: 25390858]
[51] Cao H,Zhang L,Li L,Lo S, Risk factors for acute endophthalmitis following cataract surgery: a systematic review and meta-analysis. PloS one. 2013;     [PubMed PMID: 23990980]
[52] Kim J,Ryu SY,Hong JH,Chung EJ, Incidence and risk factors for retinal detachment after cataract surgery in Korea: a nationwide population-based study from 2011 to 2015. Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie. 2019 Oct;     [PubMed PMID: 31388742]
[53] McGuigan LJ,Gottsch J,Stark WJ,Maumenee AE,Quigley HA, Extracapsular cataract extraction and posterior chamber lens implantation in eyes with preexisting glaucoma. Archives of ophthalmology (Chicago, Ill. : 1960). 1986 Sep;     [PubMed PMID: 2875707]
[54] Garg P,Roy A,Sharma S, Endophthalmitis after cataract surgery: epidemiology, risk factors, and evidence on protection. Current opinion in ophthalmology. 2017 Jan;     [PubMed PMID: 27661662]
[55] Durand ML, Endophthalmitis. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2013 Mar;     [PubMed PMID: 23438028]
[56] Lalwani GA,Flynn HW Jr,Scott IU,Quinn CM,Berrocal AM,Davis JL,Murray TG,Smiddy WE,Miller D, Acute-onset endophthalmitis after clear corneal cataract surgery (1996-2005). Clinical features, causative organisms, and visual acuity outcomes. Ophthalmology. 2008 Mar;     [PubMed PMID: 18067969]
[57] Schaumberg DA,Dana MR,Christen WG,Glynn RJ, A systematic overview of the incidence of posterior capsule opacification. Ophthalmology. 1998 Jul;     [PubMed PMID: 9663224]
[58] Tetz MR,Nimsgern C, Posterior capsule opacification. Part 2: Clinical findings. Journal of cataract and refractive surgery. 1999 Dec;     [PubMed PMID: 10609214]
[59] Apple DJ,Solomon KD,Tetz MR,Assia EI,Holland EY,Legler UF,Tsai JC,Castaneda VE,Hoggatt JP,Kostick AM, Posterior capsule opacification. Survey of ophthalmology. 1992 Sep-Oct;     [PubMed PMID: 1455302]
[60] Gandhi JS, Cystoid macular edema after cataract surgery. Journal of cataract and refractive surgery. 2018 Dec;     [PubMed PMID: 30473094]
[61] Flach AJ, The incidence, pathogenesis and treatment of cystoid macular edema following cataract surgery. Transactions of the American Ophthalmological Society. 1998;     [PubMed PMID: 10360304]
[62] Wielders LH,Schouten JS,Aberle MR,Lambermont VA,van den Biggelaar FJ,Winkens B,Simons RW,Nuijts RM, Treatment of cystoid macular edema after cataract surgery. Journal of cataract and refractive surgery. 2017 Feb;     [PubMed PMID: 28366377]
[63] Haug SJ,Bhisitkul RB, Risk factors for retinal detachment following cataract surgery. Current opinion in ophthalmology. 2012 Jan;     [PubMed PMID: 22081033]
[64] Hood CT,Sugar A, Subjective complaints after cataract surgery: common causes and management strategies. Current opinion in ophthalmology. 2015 Jan;     [PubMed PMID: 25333754]
[65] Nizami AA,Gulani AC, Cataract 2020 Jan;     [PubMed PMID: 30969521]
[66] Lamoureux EL,Fenwick E,Pesudovs K,Tan D, The impact of cataract surgery on quality of life. Current opinion in ophthalmology. 2011 Jan;     [PubMed PMID: 21088580]
[67] Schlenker MB,Thiruchelvam D,Redelmeier DA, Association of Cataract Surgery With Traffic Crashes. JAMA ophthalmology. 2018 Sep 1;     [PubMed PMID: 29955857]
[68] Tseng VL,Yu F,Lum F,Coleman AL, Cataract Surgery and Mortality in the United States Medicare Population. Ophthalmology. 2016 May;     [PubMed PMID: 26854033]
[69] Brown GC,Brown MM,Menezes A,Busbee BG,Lieske HB,Lieske PA, Cataract surgery cost utility revisited in 2012: a new economic paradigm. Ophthalmology. 2013 Dec;     [PubMed PMID: 24246824]