Question

iscussion Questions 1. Relate the patient history and circumstances of the injury and the signs and symptoms related 2. Discuss the treatments available for the patient. (See Detached Retina in your text and any 3. Relate the symptoms and signs to those of macular degeneration. (See Macular Degeneration.) to the pathophysiology of this condition. (See Detached Retina in your text.) new procedures that are being used clinically in the literature) 4. Discuss the treatment available and the prognosis for recovering his normal vision. (See Macular Degeneration and look at the clinical literature to see what seems to be working for a case such as this) How might you approach using the imaging sciences to more thoroughly evaluate, diagnose and determine treatment efficacy for this patient (suggest currently available imaging modalities as well as any you might imagine could be developed) 5.

Answer 1

1. Retinal detachment is defined as the separation of two layers of the retina; when separation occurs, vitreous humour seeps between the layers and detachment of the retina from the choroid occurs; treatment is necessary to reestablish contact between the layers to maintain blood supply.

Retinal breaks are an interruption in the full thickness of the retinal tissue, and they can be classified as tears or holes. Retinal holes are atrophic retinal breaks that occur spontaneously. Retinal tears can occur as the vitreous humour shrinks during ageing and pull on the retina.

Two major categories:

Rhegmatogenous (most common)—caused by a break or tear in the retina;

Non-rhegmatogenous —caused by leakage or exudates from beneath the retina (exudative) or by traction of the vitreous pulling on the retina (tractional)

Pathophysiology:

Most commonly, a hole or tear in the retina allows the liquid vitreous to seep between the retinal layers (rhegmatogenous).
Tumour growth or inflammation allows subretinal fluid to accumulate and cause detachment (exudative or serous).
Adhesions between the vitreous gel and retina are exposed to mechanical forces, causing separation of the retina from the retinal pigment epithelium without any break (tractional).
Liquid separates the sensory retinal layer from its choroidal blood supply.

Signs and Symptoms :

• Photopsia (light flashes)
• floaters, and "cobweb"
• "hairnet", or ring in the field of vision.
• painless loss of peripheral or central vision, "like a curtain" coming across the field of vision.

2. Surgical management involves :

*Laser photocoagulation:

involves using an intense, precisely focused light beam to create an inflammatory reaction. The light is directed at the area of the retinal break.

*Cryotherapy (cryopexy):

Uses cold to seals retinal breaks by creating an inflammatory reaction that causes an adhesion or scar

*Scleral buckling procedure:

An extraocular surgical procedure that involves indenting the globe so that the pigment epithelium, the choroid, and the sclera move toward the detached retina. Done as an outpatient with local anaesthesia.

*Intraocular procedures:

• Pneumatic Retinopexy

Intravitreal injection of gas to form a temporary bubble in the vitreous cavity that closes break and provides opposition of separated retinal layers, combined with laser photocoagulation or cryotherapy because the bubble is temporary. Patient position head so the bubble is in contact with the retinal break, the patient may need to maintain the position as much as possible for up to several weeks.

• Vitrectomy

Surgical removal of the vitreous may be used to relieve traction on the retina especially when traction results from proliferative diabetic retinopathy. May be combined with scleral bucking to provide a dual effect in relieving traction.

3. Macular degeneration is defined as the deterioration of the macula (the area of central vision) and can be age-related or exudative.

Age-related macular degeneration usually produces a slow, painless loss of vision. In rare cases, however, vision loss can be sudden. Early signs of vision loss from AMD include shadowy areas in your central vision or unusually fuzzy or distorted vision.

4. No FDA-approved treatments exist yet for dry macular degeneration, although nutritional intervention may help prevent its progression to the wet form.

For wet AMD, treatments aimed at stopping abnormal blood vessel growth include FDA-approved drugs called Lucentis, Eylea, Macugen and Visudyne used with Photodynamic Therapy or PDT. Lucentis has been shown to improve vision in a significant number of people with macular degeneration.

5. The treatment of age-related macular degeneration (AMD) has been revolutionized by the introduction of successful pharmacotherapies, such as ranibizumab, bevacizumab, and aflibercept, for the neovascular form of the disease. Data from a number of countries illustrate this point. In Denmark, the incidence of legal blindness from AMD has fallen by half between 2000 and 2010, with the bulk of the reduction occurring after the introduction of ranibizumab and bevacizumab. In Israel, a similar reduction in legal blindness has been reported since the introduction of these therapies. In Australia, it is estimated that monthly injections with ranibizumab for patients newly diagnosed with neovascular AMD would lead to a 72% reduction in incident blindness over a 2-year period. Finally, in the US it is estimated that the use of monthly ranibizumab injections would reduce the number of cases of incident blindness from 16,268 to only 4,484 individuals over a 2-year follow-up. While these drugs are undoubtedly successful in reducing visual impairment and blindness, patients with neovascular AMD typically lose some vision over time and often lose the ability to read, drive, or perform other important activities of daily living. Efforts are underway to develop new pharmacotherapies and other novel approaches to treatment. However, developing strategies to allow for earlier detection and treatment of this disease may be equally if not more effective.