Other Choroidal Disorders

Introduction

The first report of a choroidal rupture goes back to 1854, when von Graefe described it for the first time. It involves a tear of the retinal pigment epithelium (RPE), Bruch’s membrane, and choroidal tissue as a consequence of trauma to the eye. Choroidal rupture caused by blunt trauma to the eye may occur at the site of the impact in the case of direct ruptures, or as a consequence of a countercoup, just opposite to it, in indirect tears.

According to published series, up to 80% of choroidal ruptures are classified as indirect, and the vast majority of these are caused by blunt trauma. Most of them take place temporal to the optic disc and usually affect the macular area and the fovea, showing a crescent shape. On the other hand, open-globe injuries appear to be the cause of choroidal ruptures in up to 28% of the cases. In these cases lesions are more typically located anteriorly, parallel to the ora serrata .

There are several theories about the mechanism that may cause an indirect choroidal break. The most accepted suggests that antero-posterior compressions and deformations cause an equatorial expansion of the globe. This force is conducted to the optic nerve and radiated from the peripapillary uveo-scleral tether. Bruch’s membrane tissue has properties that make it the most susceptible target to be damaged in indirect traumas. While retinal tissue is more elastic than Bruch’s membrane, the sclera shows more resistance to tension thanks to its stiffness. This is why they are both usually spared.

Diseases affecting the consistency of Bruch’s membrane are more susceptible to choroidal ruptures after trauma, like angioid streaks, as will be discussed later. Older theories relating the tears to vascular necrosis as a consequence of the trauma are not as supported as the previous one.

Ocular Manifestations and Clinical Course

The most common clinical presentation is a subretinal hemorrhage that may hide the actual tear in the early phases ( Fig. 19.1.1 ) and, in rare cases, there may be multiple breaks. After blood is resorbed, the choroidal rupture becomes visible taking a crescent shape, concentric to the optic nerve head ( Fig. 19.1.2 ). Although it has not been found to be a predictive factor by some authors, initial visual acuity (VA) ranges from 20/20 to light perception, depending on the affected area.

Visual prognosis is marked by location, presence of intraocular hemorrhage, retinal involvement (retinal tears and detachment, retinal edema), and development of choroidal neovascularization (CNV).

Secretan et al. published a review of 79 cases reaching several conclusions: They stated that ruptures located less than 200 µm from the foveal avascular zone (FAZ) and between 200 and 1500 µm from the FAZ were significantly more likely to develop CNV than those located farther than 1500 µm from the FAZ. They also found breaks larger than 4000 µm to predispose for the development of CNV, wherever they were located; 82% of their patients developed CNV during the first year of follow-up.

Treatment

Although traumatic CNV usually regress spontaneously, several treatments have been proposed through the years, from photodynamic therapy (PDT), going through surgical extraction and laser photocoagulation until the age of anti-vascular endothelial growth factor (VEGF) drugs ( Fig. 19.1.3 ).

Both bevacizumab and ranibizumab have shown good results for the treatment of CNV related to choroidal ruptures. Mean number of injections goes from 2.5 injections in 52 months up to monthly injections depending on the treatment regimen established. Rosina et al. state that patients free from CNV reactivation for about a year show a smaller recurrence rate. Furthermore, each recurrence increases the risk for further reactivation; therefore, frequent controls during follow-up are mandatory. Some authors report promising results, stabilizing or improving VA in 62.9% of the eyes treated with ranibizumab.

Introduction

Angioid streaks is the term used to describe visible irregular lines that spread radially form the optic nerve, with a variable width which funduscopically seem red-brown. It is their similarity to retinal vessels that is responsible for their name, and were first described in 1889 by Doyne during the exploration of traumatized eyes.

Angioid streaks are the ophthalmoscopic manifestations of calcific degeneration and irregular breaks in Bruch’s membrane together with a consequent atrophy of the RPE above them. Calcium deposits make Bruch’s membrane more brittle and less resistant to trauma (external, muscle traction, pressure on the eye), being responsible for the choroidal ruptures involved in these patients. Latest theories demonstrate an absence of a systemic antimineralization factor that leads to the calcification Bruch’s membrane and other connective tissues that are rich in elastic fibers. Although they are not necessarily present in every affected patient, systemic associations of angioid streaks include pseudoxanthoma elasticum, Ehlers–Danlos and Marfan syndromes, Paget’s disease, acromegaly and several blood dyscrasias like thalassemia, spherocytosis, and sickle-cell anemia. Other less common conditions associated to this pathology are listed in Table 19.2.1 .

Patients showing this disease are usually asymptomatic until complications arise. The most frequent of them is the development of traumatic CNV, and prognosis depends on the macular involvement.