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Cataract

By

Leila M. Khazaeni

, MD, Loma Linda University School of Medicine

Reviewed/Revised Jan 2024
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Topic Resources

A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is surgical removal and placement of an intraocular lens.

Cataracts are the leading cause of blindness worldwide (1 Reference A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is... read more Reference ). In the United States, almost 20% of people aged 65 to 74 have cataracts that interfere with vision. Almost one in two people older than 75 has cataracts.

Lens opacity can develop in several locations:

  • Central lens nucleus (nuclear cataract)

  • Beneath the posterior lens capsule (posterior subcapsular cataract)

  • On the side of the lens (cortical cataract)—these usually do not interfere with central vision

Reference

  • 1. Hashemi H. Pakzad R, Yekta A, et al: Global and regional prevalence of age-related cataract: A comprehensive systematic review and meta-analysis. Eye 34:1357–1370, 2020. do: 10.1038/s41433-020-0806-3

Etiology of Cataract

Cataracts occur with aging. Other risk factors may include the following:

Estrogen use by women after menopause may be protective, but estrogen should not be used solely for this purpose.

Symptoms and Signs of Cataract

Cataracts usually develop slowly over years. Early symptoms may be loss of contrast, glare (ie, halos and starbursts around lights, not photophobia), needing more light to see well, and problems distinguishing dark blue from black. Painless blurring eventually occurs. The degree of blurring depends on the location and extent of the opacity. Monocular double vision or ghost images occur rarely.

With a nuclear cataract, distance vision worsens. Near vision may improve in the early stages because of changes in the refractive index of the lens; presbyopic patients may be temporarily able to read without glasses (second sight).

A posterior subcapsular cataract disproportionately affects vision because the opacity is located at the crossing point of incoming light rays. Such cataracts reduce visual acuity more when the pupil constricts (eg, in bright light, during reading). They are also the type most likely to cause loss of contrast as well as glare (halos and starbursts around lights), especially from bright lights or from car headlights while driving at night.

Diagnosis of Cataract

  • Ophthalmoscopy followed by slit-lamp examination

Diagnosis is best made with the pupil dilated. Well-developed cataracts appear as gray, white, or yellow-brown opacities in the lens. Examination of the red reflex through the dilated pupil with the ophthalmoscope Ophthalmoscopy The eye can be examined with routine equipment, including a standard ophthalmoscope; thorough examination requires special equipment and evaluation by an ophthalmologist. History includes location... read more held about 30 cm away usually discloses subtle opacities. Small cataracts stand out as dark defects in the red reflex. A large cataract may obliterate the red reflex. Slit-lamp examination Slit-lamp examination The eye can be examined with routine equipment, including a standard ophthalmoscope; thorough examination requires special equipment and evaluation by an ophthalmologist. History includes location... read more provides more details about the character, location, and extent of the opacity.

Pearls & Pitfalls

  • Examination of the red reflex through the dilated pupil with the ophthalmoscope held about 30 cm away can help identify early cataracts if a slit lamp is unavailable.

Treatment of Cataract

  • Surgical removal of the cataract

  • Placement of an intraocular lens

Frequent refractions and corrective lens prescription changes may help maintain useful vision during cataract development. Rarely, long-term pupillary dilation (with phenylephrine 2.5% every 4 to 8 hours) is helpful for small centrally located cataracts. Indirect lighting while reading minimizes pupillary constriction and may optimize vision for close tasks.

Usual indications for surgery include the following:

  • Best vision obtained with glasses is worse than 20/40 (< 6/12), or vision is significantly decreased under glare conditions (eg, oblique lighting while trying to read a chart) in a patient with bothersome halos or starbursts.

  • Patients sense that vision is limiting (eg, by preventing activities of daily living such as driving, reading, hobbies, and occupational activities).

  • Vision could potentially be meaningfully improved if the cataract is removed (ie, a significant portion of the vision loss must be caused by the cataract).

Cataract extraction and lens implant procedures

Cataract extraction is usually done using a topical or local anesthetic and IV sedation. There are 3 extraction techniques:

  • In intracapsular cataract extraction, the cataract and lens capsule are removed in one piece; this technique is rarely used.

  • In extracapsular cataract extraction, the hard central nucleus is removed in one piece and then the soft cortex is removed in multiple small pieces.

  • In phacoemulsification (a type of extracapsular cataract extraction), the hard central nucleus is dissolved by ultrasound and then the soft cortex is removed in multiple small pieces.

Phacoemulsification uses the smallest incision, thus enabling the fastest healing, and is usually the preferred procedure. Femtosecond lasers can be used in refractive laser-assisted cataract surgery prior to phacoemulsification to achieve a more precise, accurate incision and decrease risk of infection. In extracapsular extraction (including phacoemulsification), the lens capsule is not removed.

A plastic or silicone lens is almost always implanted intraocularly to replace the optical focusing power of the removed crystalline lens. The lens implant is usually placed on or within the lens capsule (posterior chamber lens). The lens can also be placed in front of the iris (anterior chamber lens) or attached to the iris and within the pupil (iris plane lens). Iris plane lenses are rarely used in the United States because many designs led to a high frequency of postoperative complications. Multifocal intraocular lenses are newer and have different focusing zones that may reduce dependence on glasses after surgery. Patients occasionally experience glare with these lenses, especially under low-light conditions, and also have problems with reduced contrast sensitivity.

Postsurgical care and complications

In most cases, a tapering schedule of topical antibiotics and topical corticosteroids (eg, prednisolone acetate) along with topical nonsteroidal anti-inflammatory drugs (NSAIDs; eg, ketorolac) are used for up to 4 weeks post surgery. Antibiotics, as well as corticosteroids and NSAIDs, can also be injected into the eye (intracameral) at the conclusion of cataract surgery, with a reduced need for topical eyedrops postoperatively (a technique called "dropless cataract surgery"). Several large, controlled studies show that intracameral antibiotics decrease postoperative endophthalmitis (1, 2 Treatment references A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is... read more Treatment references ). Two phase 3 studies also showed that intracameral dexamethasone was safe and effective (3 Treatment references A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is... read more Treatment references ). Patients often wear an eye shield while sleeping and should avoid the Valsalva maneuver, heavy lifting, excessive forward bending, and eye rubbing for several weeks.

Treatment references

  • 1. Melega MV, Alves M, Cavalcanti Lira RP, et al: Safety and efficacy of intracameral moxifloxacin for prevention of post-cataract endophthalmitis: Randomized controlled clinical trial. J Cataract Refract Surg 45(3):343-350, 2019. doi: 10.1016/j.jcrs.2018.10.044

  • 2. Shorstein NH, Winthrop KL, Herrinton LJ: Decreased postoperative endophthalmitis rate after institution of intracameral antibiotics in a Northern California eye department. J Cataract Refract Surg 39(1):8-14, 2013. doi: 10.1016/j.jcrs.2012.07.031

  • 3. Walters T, Bafna S, Vold S, et al: Efficacy and safety of sustained release dexamethasone for the treatment of ocular pain and inflammation after cataract surgery: Results from two phase 3 studies. J Clin Exp Ophthalmol 7.4 (2016):1-11.

  • 4. Powe NR, Schein OD, Gieser SC, et al: Synthesis of the literature on visual acuity and complications following cataract extraction with intraocular lens implantation. Cataract Patient Outcome Research Team. Arch Ophthalmol. 112(2):239-252, 1994. doi: 10.1001/archopht.1994.01090140115033. Erratum in: Arch Ophthalmol 112(7):889, 1994.

  • 5. Greenberg PB, Liu J, Wu WC, et al: Predictors of mortality within 90 days of cataract surgery. Ophthalmology 117(10):1894-9, 1899.e1, 2010. doi: 10.1016/j.ophtha.2010.02.009

Prevention of Cataract

Prevention references

  • 1. Mares JA, Voland R, Adler R, et al: Healthy diets and the subsequent prevalence of nuclear cataract in women. Arch Ophthalmol 128(6):738-749, 2010. doi: 10.1001/archophthalmol.2010.84

  • 2. Mathew MC, Ervin AM, Tao J, et al: Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract. Cochrane Database Syst Rev6(6):CD004567, 2012. doi: 10.1002/14651858.CD004567.pub2

  • 3. Christen WG, Glynn RJ, Manson JE, et al: Effects of multivitamin supplement on cataract and age-related macular degeneration in a randomized trial of male physicians. Ophthalmology 121(2):525-534, 2014. doi: 10.1016/j.ophtha.2013.09.038.

Key Points

  • Modifiable risk factors for cataract include exposure to ultraviolet light; use of alcohol, tobacco, and systemic corticosteroids; and poor control of blood glucose.

  • Symptoms include loss of contrast, glare (halos and starbursts around lights), and eventually visual blurring.

  • Diagnosis is by examination with the eye dilated.

  • Surgical removal and placement of an intraocular lens are usually indicated if the cataract contributes to visual loss that interferes with activities of daily living, causes bothersome glare, or reaches certain degrees of severity (eg, best-corrected visual acuity worse than 20/40).

Drugs Mentioned In This Article

Drug Name Select Trade
4-Way Nasal, Ah-Chew D, AK-Dilate, Anu-Med, Biorphen, Formulation R , Foster & Thrive Nasal Decongestion, Gilchew IR, Hemorrhoidal , IMMPHENTIV, Little Remedies for Noses, Lusonal, Mydfrin, Nasop, Nasop 12, Neofrin, Neo-Synephr, Neo-Synephrine, Neo-Synephrine Cold + Allergy, Neo-Synephrine Extra Strength, Neo-Synephrine Mild, Neo-Synephrine Non-Drowsy Cold + Allergy, Ocu-Phrin, PediaCare Children's Decongestant, PediaCare Decongestant, PediaCare Infants' Decongestant, Sinex Nasal, Sudafed PE, Sudafed PE Children's Nasal Decongestant , Sudafed PE Congestion, Sudafed PE Sinus Congestion, Sudogest PE, Vazculep
AK-Pred, AsmalPred, Econopred, Econopred Plus, Flo-Pred, Hydeltrasol, Inflamase Forte, Inflamase Mild, Millipred , Millipred DP, Millipred DP 12-Day, Millipred DP 6 Day, Ocu-Pred , Ocu-Pred A, Ocu-Pred Forte, Omnipred, Orapred, Orapred ODT, Pediapred, Pred Mild, Predalone, Pred-Forte, Prednoral, Pred-Phosphate , Prelone, Veripred-20
Acular, Acular LS, Acular PF, Acuvail , SPRIX, Toradol
AK-Dex, Baycadron, Dalalone, Dalalone D.P, Dalalone L.A, Decadron, Decadron-LA, Dexabliss, Dexacort PH Turbinaire, Dexacort Respihaler, DexPak Jr TaperPak, DexPak TaperPak, Dextenza, DEXYCU, DoubleDex, Dxevo, Hemady, HiDex, Maxidex, Ocu-Dex , Ozurdex, ReadySharp Dexamethasone, Simplist Dexamethasone, Solurex, TaperDex, ZCORT, Zema-Pak, ZoDex, ZonaCort 11 Day, ZonaCort 7 Day
Avelox, Avelox ABC Pack, Avelox I.V., MOXEZA, Vigamox
A Mulsin, Aquasol A, Dofsol-A
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