Continuing Education Activity

A cataract is a disease of the eye in which the normally clear lens has opacified which obscures the passage of light. It is a gradually progressive disease and a significant cause of blindness around the world. This activity illustrates the evaluation and treatment of cataracts and reviews the role of the interprofessional team in managing patients with this condition.

Objectives:

• Outline the etiology of cataracts.
• Describe the reduced visual acuity in the physical exam findings of those with cataracts.
• Summarize the comprehensive ophthalmic examination in the evaluation of patients with cataracts.
• Identify the importance of improving care coordination among the interprofessional team to improve outcomes for patients with cataracts.

Introduction

A cataract is a clouding or opacification of the normally clear lens of the eye or its capsule (surrounding transparent membrane) that obscures the passage of light through the lens to the retina of the eye. This blinding disease can affect infants, adults, and older people, but it predominates the latter group. It can be bilateral and vary in severity. The disease process progresses gradually without affecting daily activities early on, but with time, especially after the fourth or fifth decade, the cataract will eventually mature, making the lens completely opaque to light interfering with routine activities. Cataracts are a significant cause of blindness worldwide. Treatment options include correction with refractive glasses only at earlier stages, and if cataract mature enough to interfere with routine activities, surgery may be advised, which is very fruitful.

Etiology

Multiple factors responsible for developing cataracts include the following:

Congenital cataract: Can be unilateral or bilateral - studies have documented a close association between congenital cataract and maternal nutrition, infections (Rubella and Rubeola), and deficiency of oxygenation due to placental hemorrhage.

Age-related (senile cataract): Most common type of cataract

Traumatic injury[1][2]: Most common cause of unilateral cataract in young adults

• Perforating trauma
• Blunt trauma: causing a characteristic flower-shaped opacity
• Electric shock:  a rare cause of cataract, causing diffuse milky-white opacification and multiple snowflakes like opacities, sometimes in a stellate subcapsular distribution
• Ultraviolet radiation: if intense may rarely cause true exfoliation of the anterior lens capsule and cataract
• Ionizing radiation: usage for ocular tumor treatment and in cardiological interventions may cause posterior subcapsular opacities
• Chemical injuries: naphthalene, thallium, lactose, galactose

Systemic Diseases:

• Myotonic dystrophy
• Atopic dermatitis
• Neurofibromatosis type 2

Endocrine Diseases[3]:

• Diabetes mellitus
• Hypoparathyroidism
• Cretinism

Primary Ocular Diseases:

•  Chronic anterior uveitis: the most common cause of secondary cataract
•  Acute congestive angle closure: may cause small anterior grey- white subcapsular or capsular opacities, glaukomflecken
•  High myopia: may cause posterior subcapsular lens opacities and early-onset nuclear sclerosis, worsening the myopic refractive error
•  Hereditary fundus dystrophies: i.e., retinitis pigmentosa, Leber congenital amaurosis, gyrate atrophy and Stickler syndrome, may cause posterior and anterior subcapsular lens opacities

Drugs: Corticosteroids and anticholinesterase inhibitors can cause both posterior and anterior subcapsular opacities respectively

Poor nutrition[4]: a diet deficient in antioxidants and vitamins

Alcohol use disorder

Smoking

Epidemiology

Prevalence and Incidence

Many studies in 2010 reveal that cataracts are most common in the White American race, where prevalence ranges from 17 to 18% per 100 people. Blacks were the second-highest affected by cataracts, with a 13% prevalence rate, followed by Hispanics with a prevalence rate of almost 12%.

Age

Onset is gradual and progressive commonly in the older age group, typically in the fifth and sixth decade, though cases have been reported in children and the elderly as well.

Sex

Recent studies reveal that the disease is more common in women than men, with a male to female ratio of 1 to approximately 1.3.

Pathophysiology

The lens is a transparent structure made up of fibers (modified epithelial cells) enclosed in a membranous structure called lens capsule. Lens matter consists of two main parts:

• Cortex (superficial part) - containing younger fibers
• Nucleus (deeper part) - containing older fibers

Many degenerative processes denature and coagulate lens proteins present in lens fibers by different mechanisms, which result in loss of transparency and, ultimately, cataract formation.[5] The various mechanisms involved are as follows:

• Disturbances occurring at any level of lens growth (congenital cataract)
• Fibrous metaplasia of lens epithelium (subcapsular cataract)
• Cortical hydration between lens fibers (cortical cataract)
• Deposition of certain pigments, i.e., urochrome (nuclear cataract)

All these processes ultimately lead to an opaque lens behind the pupil, making it extremely difficult for the patient to carry on with routine activities.

History and Physical

History

The patient may present with one of the following symptoms:

• Decrease or blurring in the vision: gradual and painless; unilateral or bilateral depending upon the eye being affected without and at mature stages even with glasses
• Diplopia or polyopia: mostly uniocular but can be binocular- this is due to multiple refractions through clear areas between the opacities
• Colored halos around the light: Rainbow halos; possibly due to the collection of water drops between layers of lens fibers acting as a prism splitting light into its seven colors
• Sensitivity to glare: especially headlights of automobiles and sunlight 
• Increased frequency to change refractive glasses: as the cataract matures, a person may visit his ophthalmologist more often for refraction
• Disturbance in color vision: fading or yellowing of objects

Physical Findings

Following findings can be noticed during a thorough ophthalmic examination depending upon the part of the lens involved:

      Visual Acuity

• Decreased unilaterally or bilaterally depending upon the affected eye

      Cortical Cataract

• Wedge-shaped opacity with clear areas of lens matter mostly present at the periphery (incipient cortical cataract)
• Well-developed wedge-shaped opacity (progressive cortical cataract)
• Advanced opacity with a greyish lens, clear cortex, and an iris shadow (immature cortical cataract)
• Findings of the immature stage but with a swollen lens due to the accumulation of fluid making anterior chamber shallow (intumescent cortical cataract)
• The entire opaque cortex with the absence of iris shadow (mature cortical cataract)
• Milky fluid bag with lens nucleus present at the bottom due to liquefaction of the cortex without an iris shadow and a shallow anterior chamber (hypermature cortical cataract)

      Nuclear Cataract

• Dark brown or black lens with an iris shadow
• No fundal view due to dark opacity in the center against a red glow
• No fourth Purkinje image

      Systemic Diseases

• Diabetes mellitus: classic snowflake cortical opacities 
• Myotonic dystrophy: Christmas tree cortical cataract which later evolves into wedge-shaped cortical and subcapsular opacities resembling a star-like in conformation 
• Atopic dermatitis: characteristic shield-like dense anterior subcapsular plaques 
• Neurofibromatosis type 2: mixed opacities; can be subcapsular, capsular or cortical

Evaluation

Cataracts can be evaluated by a number of steps as follows:

History

• The chief complaint of the patient, i.e., a decrease of vision
• Past ophthalmic history
• Any systemic disease-causing or aggravating the symptoms

Comprehensive ophthalmic examination

1. Visual acuity: can be assessed by Snellen chart to identify the severity of the disease and limitations in routine activities of life
2. Refraction: Important factor to plan management
3. Cover test: poor vision caused by cataract can be a reason for a divergent squint
4. Slit-lamp examination

• Pupillary responses: to check the shape of the pupil, afferent and efferent pathways and relative afferent pupillary defect
• Adnexal examination: a thorough examination is needed to exclude any adnexal pathology, i.e., dacryocystitis, blepharitis, chronic conjunctivitis, lagophthalmos, ectropion, entropion, and tear film abnormalities - these conditions may predispose to endophthalmitis, so their diagnosis and optimization are necessary to treat cataract
• Cornea: important to asses whether cornea will able to handle operative trauma - arcus senilis is an important finding because it can obstruct the operative field clarity
• Anterior Chamber: a shallow anterior chamber can make cataract surgery extremely difficult
• Lens: part of the lens involved can be an important factor to plan our surgical technique - nuclear cataract is harder while cortical cataract is softer in consistency
• Fundus Examination: any pathology in the fundus, i.e., age-related macular degeneration can be an important factor to determine visual outcome after surgery that is why a thorough fundal examination is critical

Investigations

The following investigations can help diagnose and plan the management of the disease:

• Intraocular pressure: to rule out glaucoma
• Dark room tests: direct and indirect ophthalmoscopy
• Fundoscopy: to rule out any vitreous or retinal pathology
• Biometry: for intraocular lens (IOL) placement during surgery
• Peripheral Retinal Assessment: testing the projection of light in all quadrants
• Macular function test: like cardboard test (two-point discrimination), Maddox rod test, the laser interferometry, foveal electroretinogram, photo stress test
• Ultrasound scan: B-scan is advised to see retinal detachment or any vitreous pathology
• Systemic diseases: Blood glucose levels, electrocardiography, echocardiography, ultrasonography
• Baseline tests: Complete blood count, liver function test, renal function test, bleeding profile, Hepatitis B and C screening, chest x-ray

Treatment / Management

The treatment choice depends upon the degree of opacity sufficient enough to cause difficulty in performing essential daily activities. Following treatment modalities are available:

1. Medical: If visual acuity is 6/24 or better, pupillary dilatation with 2.5% phenylephrine or refractive glasses is enough to carry on routine activities, and surgery is not required. Cyclopentolate and atropine can also be useful. Recently, there are also cataracts drops under trial, which can dissolve cataracts.
2. Surgery: If visual acuity is worse than 6/24 or there is a medical indication (phacolytic glaucoma, phacomorphic glaucoma, retinal detachment) in which a cataract is adversely affecting the health of the eye, surgery is always needed.

• Congenital Cataract: No treatment is necessary if visual acuity is more than 6/24, and a patient can carry out their normal routine activities. Refractive glasses can be advised for the blurring of vision or diplopia. If visual acuity falls below 6/24, surgery is needed, and the surgeon can opt for one of the following surgical procedures depending upon patients' complaints and severity of the disease.[6]
  • Irrigation and aspiration of the lens
  • Irrigation and aspiration of the lens with intraocular lens (IOL) implantation
  • Irrigation aspiration of the lens with IOL, anterior vitrectomy and primary posterior capsulotomy
• Senile Cataract: Treatment options are the following[7][8]:
  • Medical: No medical treatment is effective once the cataract has become mature.
  • Surgical: Mature cataract has a very hard nucleus, and one of the following methods are used to extract lens:
    • Extracapsular cataract extraction: a procedure of choice
    • Intracapsular cataract extraction: an old technique not used frequently due to complications 
    • Phaco-emulsification: a modification of extracapsular cataract extraction (ECCE) with less astigmatism and early visual recovery
    • Laser phacolysis: a recent advancement under trial
• Management of general conditions before surgery: Many general health conditions require optimization before surgery for better results.
  • Diabetes mellitus
  • Hypertension
  • Myocardial Infarction
  • Angina
  • Respiratory Infection
  • Stroke
  • Leg ulcer
  • Viral hepatitis
  • AIDS
  • Epilepsy
  • Parkinson disease
  • Rheumatoid arthritis

Differential Diagnosis

The differential diagnosis of cataract includes many disorders such as:

• Glaucoma
• Refractive errors
• Macular degeneration
• Diabetic retinopathy
• Corneal dystrophies and degenerations
• Optic atrophy
• Retinitis pigmentosa

Prognosis

Prognosis of cataract depends upon multiple factors such as:

• The degree of visual impairment
• Type of cataract
• Timing of intervention
• Mode of intervention
• Quality of life
• Unilateral or bilateral involvement of the eye
• Presence of another systemic disease

In most cases, surgery restores vision very effectively. The presence of another systemic disease, time of intervention, and mode of surgery can be instrumental in determining the visual outcome. Recent studies reveal that in most of the cases, the prognosis is excellent after surgery almost 70 to 80%. Most patients show excellent results after surgery if they strictly follow postoperative instructions and medication regimens advised by their ophthalmologist.[9] A routine eye examination is advisable, which will detect any cataract development in the other eye. Many patients with a monofocal IOL may require refractive glasses to achieve their best visual acuity after surgical cataract removal.[10] Gradual opacification of the posterior capsule can develop in a large number of patients that can affect the patient's vision (secondary cataract).

Complications

Cataract cause multiple complications discussed as follows:

Congenital cataract: These can be disease-related or surgery related[11]:

• Disease-related complications: corneal ulcer, corneal perforation (acquired anterior capsular cataract), blindness
• Surgery-related complications: uveitis, posterior capsular thickening, aphakia, after cataract, growth-related refractive changes, glaucoma, retinal detachment

Acquired cataract: These can be disease-related or surgery related:

• Disease-related complications: acute congestive glaucoma (Intumescent stage), phacolytic glaucoma, iritis, subluxation of the lens, secondary glaucoma(hypermature stage), blindness
• Surgery-related complications: these are classified as follows:
  • During surgery: posterior capsular rupture, hyphaema, expulsive hemorrhage, corneal burn, nucleus drop in vitreous
  • Post surgery[12][13]: iris prolapse, delayed anterior chamber formation, infections like endophthalmitis or panophthalmitis, striate keratitis, malpositioning of IOL, pseudophakic glaucoma, cystoid macular edema, dysphotopsia, ptosis, retinal detachment, posterior capsular thickening, and opacifications

Deterrence and Patient Education

The patients should receive education about:

• Risk factors of the disease
• Complications of the disease
• Treatment options of the disease
• Complications of the surgery
• The regular need for a follow-up

Visual acuity charts and slit-lamp examination should be used on regular bases at every follow-up to detect any impairment in visual acuity after cataract or any complication of the surgery. The patient should be advised to wear spectacles in the sunlight to avoid damage by ultraviolet rays. A thorough systemic evaluation is advisable to rule out any systemic disease which may affect the outcome of the treatment.

Enhancing Healthcare Team Outcomes

Anytime a patient visits a clinic or emergency department for symptoms of visual impairment, the primary care provider should be responsible for quick referral of the patient to an ophthalmologist.[14]

The management of cataract differs based on the severity of the disease, visual impairment, and age of the patient. The mainstay of treatment is usually surgical cataract extraction. Patients who have mild symptoms can receive treatment as an outpatient with refractive glasses and pupillary dilatation. Those with more severe disease or with advanced age should be advised elective surgery as a day-case procedure.[15]

Response to refractive glasses in the early stage of cataract is usually satisfactory. If outpatient therapy by refractive glasses and pupillary dilatation fails to show improvement, patients should undergo hospitalization for surgical cataract removal with intraocular lens implantation. No studies have revealed any link between prescription of systemic steroids or steroids eye drops and the recurrence or complication of cataract, and thus steroids are not routinely prescribed. For most patients who obtain prompt treatment, the results are excellent, but for those who have a delay in treatment or have a mature or complicated disease, there may be steady or poor vision following recovery.

Diagnosis and treatment of cataracts require an interprofessional team approach, to include primary care providers (physicians, PAs, NPs), specialists (ophthalmologists, ophthalmic surgeons), and nursing support. The primary care provider, nurse practitioner, and pharmacist should educate the patient on steps to prevent cataracts. The patient should be urged to wear sunglasses when going out, wear a face mask of eye goggles when working with hazardous fluids or playing sports, and see an eye doctor on a regular basis. In addition, patients prescribed corticosteroid drugs should regularly have their eyes checked to ensure that they are not developing cataracts. This approach helps to ensure timely and effective patient care and optimal outcomes. [Level 5]