SPECIAL SENSES: PART 2

Cataracts occur when the eye's lens becomes opaque, distorting light transmission to the brain and causing blurry vision, similar to a dusty camera lens. This condition can lead to progressive vision loss and even blindness. There are two main types: primary (due to aging, congenital conditions, or traumatic injury) and secondary (resulting from underlying conditions like diabetes, maternal rubella, severe myopia, UV exposure, steroid use, chemoagents, and smoking). Early signs include blurred or distorted central vision, decreased color perception, absence of a red reflex, double vision (diplopia), reduced visual acuity, and the eye appearing milky or white. It is typically painless and can cause a shift in color perception to yellow-brown (brunescence).

Cataracts are diagnosed using a Snellen visual acuity test to assess vision reduction, ophthalmoscopy to examine the eye, and slit lamp biomicroscopic examination for internal eye inspection. The definitive treatment for cataracts is surgical intervention, which involves removing the opaque lens and replacing it with an artificial, clear one. Common surgical procedures include phacoemulsification (breaking up and extracting the lens with ultrasonic vibration), intracapsular extraction (removing the lens and capsule completely), and extracapsular extraction (removing the lens while preserving the capsule).

Before cataract surgery, patients should be instructed not to touch their eyes to prevent contamination. Prophylactic antibiotics are administered to reduce infection risk. Mydriatics (e.g., neosynephrine, atropine) are given to dilate the pupil, allowing the surgeon better visibility. Cycloplegics, which are muscle relaxants, are also administered to relax the ciliary muscle, preventing eye movement during surgery and ensuring accuracy. Common examples of mydriatics include atropine, while pilocarpine is a common miotic that constricts the pupil. Antimicrobial agents like gentamicin are also used pre-operatively.

After cataract surgery, antibiotics and anti-inflammatory drugs (corticosteroids) are given to prevent infection and reduce inflammation. Patients should wear protective glasses (not reading glasses) and elevate the head of the bed to 30-45 degrees to decrease intraocular pressure (IOP). An eye patch is worn for 24 hours on the operated side to prevent movement. Belongings should be placed on the non-operative side, and the client oriented to their environment to prevent falls. Patients should avoid the Valsalva maneuver and constipation, as both increase IOP. Ambulation is encouraged, and the client should be turned to their back or non-operative side. Avoid eye straining, rubbing, or pressure. Lifting objects heavier than 5 lbs is prohibited to prevent increased IOP. Watch out for sudden eye pain, restlessness, increased pulse, and bright red drainage from the dressing, as these indicate potential complications like increased IOP or bleeding, and require immediate reporting to the healthcare provider.

Macular degeneration involves the deterioration of the macula, which is responsible for central vision. While peripheral vision usually remains intact, patients experience loss of central vision. This condition is irreversible, particularly in dry AMD. It involves the buildup of yellow lipid and protein deposits called drusen near the retina, atrophy (tissue cell death), and sometimes subretinal hemorrhage (bleeding beneath the retina). Risk factors include increasing age, smoking, hypertension, overweight/obesity, hyperopia (farsightedness), and familial incidence.

Macular degeneration has two main types: dry and wet. Dry macular degeneration is characterized by a gradual onset, lack of fluid or bleeding in the macula (non-neovascular, non-exudative), and no specific treatment, only monitoring. It involves the atrophy of tissue cells, gradual blocking of retinal capillaries, and accumulation of drusen, leading to a gradual decrease in central vision and symptoms like missing letters in words or blank spots. Wet macular degeneration has an abrupt onset and is characterized by neovascularization (formation of new, weak blood vessels) and exudative changes (fluid accumulation). These abnormal vessels leak fluid and bleed, causing edema and fibrosis, leading to rapid visual changes. Patients may see straight lines appear crooked or distorted (metamorphopsia), and a scar can form, resulting in central vision loss.

There is no known cure for dry AMD. For wet macular degeneration, medical management includes administering Ranibizumab and Bevacizumab, which stop the growth of abnormal blood vessels. Laser therapy and photodynamic therapy can be used to seal leaking blood vessels and prevent bleeding. Nursing management primarily involves monitoring, such as using the Amsler grid once a week to track the progression of the disease.