Cataract Treatment

Goals of Therapy

• Improve visual function
  • Increased ability to read or do near work
  • Reduced glare
  • Enhanced ability to function in dim light
  • Enhanced binocular vision and ability to perceive depth
  • Enhanced color and peripheral vision
  • Enhanced optically corrected vision or uncorrected vision with reduced dependence on eyeglasses
• Reduce visual symptoms
• Achieve desired refractive outcome
• Improve physical function
  • Increased ability to perform activities of daily living
  • Increased ability to resume occupation
  • Increased mobility (walking, driving)
• Improve mental health and emotional well-being
  • Reduced fear of falling
  • Improved social engagement
  • Better injury or accident avoidance
  • Enhanced self-esteem and independence
  • Ease from fear of blindness
• Improve quality of life

• Consists of pre-operative, intra-operative, and post-operative medications

Pre-operative Agents

• Used to dilate the pupils, as anti-infective prophylactic agents, and as anesthetics

Pupil Dilatation

• Mydriatic and cycloplegic agents are used together before extracapsular nuclear expression or phacoemulsification
  
  • Eg Tropicamide (cycloplegic), Phenylephrine (mydriatic)

• Non-steroidal anti-inflammatory drugs (NSAIDs) are used to prevent pupillary miosis, decrease inflammation due to surgery, decrease intra-operative pain, and prevent post-operative cystoid macular edema
  
  • Eg Diclofenac, Ketorolac, Nepafenac
  • Diclofenac effectively maintains mydriasis during surgery

Anti-infective Prophylaxis

• Pre-operatively, the most important source of infection is the patient’s own conjunctival and lid skin flora
• Common infecting agents are: Staphylococci, diphtheroids, streptococci, gram negative bacilli
• 4th generation fluoroquinolones are the preferred agents because they penetrate better, have broader spectrum of coverage, and have lower incidence of resistance
• Moxifloxacin appears to have better tissue penetration than Gatifloxacin, although equally safe
• Complete conjunctival sterility, through the elimination of natural flora, is not usually possible with the use of anti-infective prophylaxis
• Povidone-iodine (5%), a topical antiseptic, dropped into the conjunctival sac pre-operatively and allowed to stay for at least 2 minutes is one of the most effective way to decrease the bacterial flora
  
  • Appears to be equally effective as pre-op topical antibiotics
  • Presence of lidocaine gel prior to povidone-iodine instillation appears to diminish its antimicrobial efficacy

Anesthetics

• Choice of anesthesia to be used, the expected pain, discomfort, consciousness level, visual experiences and complications should be discussed with the patient
• Safety, efficacy and completion of surgery with the least pain and lowest risk for the patient should be considered in choosing the type of anesthesia to be used
• General anesthetics are indicated for patients with medical, psychosocial and surgical indications, who are unable to comply with instructions or unable to communicate
• Local or regional is the most preferred mode of anesthesia
  
  • Most commonly used - topical
  • Other examples - peribulbar or retrobulbar injection, sub-Tenons injection, and intracameral
  • Sharp needle local anesthesia techniques have a higher risk of ocular and systemic complications than topical techniques and should only be used when the anesthetist and ophthalmologist consider it absolutely necessary
  • Disadvantages: Increased surgical difficulty in the absence of akinesia and possible need to augment the anesthesia in the event of intra-operative complications
  • Patient cooperation and ability to follow instructions are essential

Intra-operative Agents

• Include irrigating solutions and its additives, ophthalmic viscosurgical devices, and intracameral antibiotics
• Generally, the addition of mydriatics, antibiotics, epinephrine, or lidocaine, is not recommended by the companies that produce irrigating solutions for cataract surgery due to possible effects on the pH, chemical stability, or osmolarity
  
  • Hence, caution is warranted

• Use of antibiotics intracamerally is controversial
  
  • Surgical techniques may play the most critical role in contamination (eg anterior chamber), and that antibiotics administered with the irrigating solutions may only minimally contribute to reduce the risk of endophthalmitis

• Intracameral antibiotics are effective in reducing post-operative endophthalmitis rates
  
  • Intracameral Cefuroxime was noted to be effective in producing 80% reduction
  • Several studies have indicated that intracameral Moxifloxacin injection may be safe for use for endophthalmitis prophylaxis

• Choice of miotic agents depends on the desired clinical features
  
  • Acetylcholine takes <1 minute to act, relatively brief duration of action, miosis for 10 minutes
  • Carbachol has an onset of time of 2 minutes, 2-24 hours duration of action

Post-operative Agents

Antibiotics

• Treatment duration may vary from 5 days for uncomplicated cases, to weeks for prolonged inflammation
• Choice of antibiotics depends on the presence of drug resistance, eg Gentamicin vs Moxifloxacin or Gatifloxacin
• Route of administration may also vary, but topical is the most prevalent
• Subconjunctival injections deliver high levels to the aqueous humor but have a greater risk of eye perforation, macular infarction, subconjunctival hemorrhage and retinal toxicity
• Oral or parenteral route may reach substantial levels in the anterior chamber but do not provide any advantages over topical routes; tantamount to increased side effects

Corticosteroids and Non-Steroidal Anti-inflammatory Drugs (NSAIDs)

• Both appears to be equally efficacious in reducing post-operative noninfectious inflammation
  
  • No difference in astigmatic decay

• Topical steroids (eg Prednisolone acetate and Dexamethasone phosphate) are most commonly used
• NSAIDs may be used in patients with contraindications to corticosteroids and with herpes simplex infection
• NSAIDs are contraindicated in patients with compromised ocular surfaces
• Increased risk of corneal or scleral perforation in the presence of epithelial defect when NSAIDs are used alone, without concomitant administration of corticosteroids
• Pretreatment with an NSAID reduces post-op inflammation as long as the drug is administered over a period of 3 days
• Addition of NSAID to antibiotic-corticosteroid combination has been reported to reduce the incidence of noninfectious post-op inflammatory conditions
• Rimexolone has been shown to have less potential to cause increase in intraocular pressure compared to Dexamethasone, Prednisolone, or Betamethasone

• Counsel the patient regarding cataract-related visual symptoms
• Give reassurance about the cause of visual disability
• Prescribe new eyeglasses (lenses with equal base curves and center thicknesses) where appropriate to improve vision
• Control illumination to reduce glare problems by incorporating filters into the spectacles
• By using a filter that blocks light with wavelengths shorter than 480 nm, an improved visual acuity and contrast sensitivity may be obtained
• Modify exposure to risk factors (eg smoking cessation, blood sugar level control)
• Inform patients that are long-time users of corticosteroids that they have high risk of having cataract and should seek consult to their physician for alternative
• Avoid exposure to UVB lights by wearing brimmed hats and UVB blocking sunglasses
• Maintain BMI at <27.8 as values greater have increased risk of developing cataract
• Safety glasses should be worn when performing high-risk activities at work or for recreation
• Follow up at 4- to 12-month intervals should be done to evaluate ocular health and vision and to determine whether functional disability develops