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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. Cataract surgery is the most effective, and currently, the only approved intervention for cataracts regardless of etiology. This activity presents the pathology of cataracts as well as the most common surgical technique, complications, and outcomes of cataract surgery. Objectives: Review the pathogenesis of cataracts. Describe the various cataract surgery techniques as well as their advantages and disadvantages. Identify the most common and the most serious complications of cataract surgery. Outline the indications and contraindications of cataract surgery Access free multiple choice questions on this topic.

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.

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]

Complications can be divided into 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 as 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]

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]

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 a loss of transparency can be seen. On slit lamp, pigment cells present in the anterior vitreous are a sensitive finding. Depending on the presentation, treatment can include laser-pexy, pneumatic retinopexy, pars plana vitrectomy, or scleral buckle.[4]

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 a loss of transparency can be seen. On slit lamp, pigment cells present in the anterior vitreous are 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]

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.