Other Choroid Disorders

This is the pigmented, highly vascular layer of the globe lying between the sclera (on the outside) and the retina (on the inside).¹ It is one of the three components of the uveal tract and is shaped a little like the body of a rounded wine glass. The optic nerve emerges at its base and the other two components of the uveal tract sit anteriorly: the ciliary body lies around the rim and the iris stretches over the opening. It is made up of three layers, each of which can be affected by disease processes. There is the external vessel layer, the capillary layer and the internal sheet-like Bruch's membrane. The main function of the choroid is to nourish the outer layers of the retina but it is also thought to regulate retinal heat, to assist in the control of intra-ocular pressure and the pigment absorbs excess light so avoiding reflection. The choroid can be subject to inflammatory disorders (often in conjunction with the retina: chorioretinitis), tumour formation (such as choroidal melanoma) and a number of other disorders outlined below.

• Choroideremia - this is a very rare condition that is inherited in an X-linked recessive manner and only affects males. Patients present in the first decade of life with an inability to see in dim conditions (nyctalopia) and a number of abnormalities can be seen both on examination of the fundus and on functional testing of the retina. Vision is usually usefully retained until about the sixth decade of life after which there is severe visual loss.
• Gyrate atrophy - this is another inherited disorder (autosomal recessive) characterised by axial myopia (short-sightedness caused by a long axis between the front and the back of the eye) and nyctalopia. There will be chorioretinal atrophy present and elevated orthinine levels in the plasma, urine, cerebrospinal fluid and aqueous humour (due to the lack of the orthinine degrading enzyme, keto-acid aminotransferase). Two subgroups of patients are identified based on their response to treatment with vitamin B6 (pyridoxine): those responsive to treatment have a more slowly progressing course of the disease.
• Central areolar choroidal dystrophy - autosomal dominant inherited condition presenting in the fourth to fifth decade of life with poor central vision and nyctalopia. Both eyes tend to be affected and the prognosis is poor with severe visual loss by the sixth to seventh decade of life.
• Diffuse Choroidal atrophy - another autosomal dominant inherited condition similar to central areolar choroidal dystrophy. Patients tend to present a decade earlier and early macular involvement rapidly impairs vision.
• Helicoidal peripapillary chorioretinal degeneration - autosomal dominant condition presenting in childhood characterised by strips of choroidal atrophy that variably affect the individual: there may be early age visual loss or elderly mild visual impairment.
• Pigmented paravenous retinochoroidal atrophy - a rare condition usually found in young men with no clear inheritance pattern and a good prognosis due to rarity of macular involvement.

These are a group of conditions characterised by chorioretinal inflammation:

Acute multifocal posterior placoid pigment epitheliopathy (AMPPE)

• Nature - this is an uncommon, idiopathic, bilateral, self-limiting condition. Often associated with HLA-B7 and HLA-DR2
• Presentation - third to fifth decade in life, after a 'flu-like illness in about 1/3 of the cases: progressive subacute impairment in one eye, followed by the other a few days later
• Investigations - fluorescein angiography
• Treatment - none
• Prognosis - generally very good although in those patients who get recurrent episodes, a residual paracentral scotoma may remain.

Serpinginous choroidopathy

• Nature - uncommon idiopathic bilateral progressive disease with a prolonged, fluctuating course over many years. Relapses occur after several months remission.
• Presentation - fourth to sixth decade in life. There is unilateral blurring of vision and image distortion (metamorphopsia) with the fellow eye being affected some time later (this time period varies).
• Investigations - fluorescein angiography
• Treatment - monotherapy: cyclosporin or triple therapy: systemic steroids, azathioprine and cyclosporin
• Prognosis - generally poor as recurrent episodes cause progressive atrophy and 50% of patients have foveal involvement, so markedly affecting vision.

Birdshot retinochoroidopathy

• Nature - uncommon, chronic bilateral inflammatory disease. It is thought to have an autoimmune aetiology; 90% of these patients are positive for HLA-A29.
• Presentation - sixth to seventh decade in life. There is blurring of vision (the symptoms are often disproportionate to the
  visual acuity) as well as floaters, nyctalopia and some degree of disturbance of colour vision.
• Investigations - fluorescein angiography, indocyanine green angiography, electroretinogram
• Treatment - there is no gold standard management but currently, a course of systemic steroids or cyclosporin are favoured options
• Prognosis - 80% follow a chronic course of several years with visual impairment secondary to subsequent cystoid macular oedema.

Punctate inner choroidopathy (PIC)

• Nature - uncommon, idiopathic bilateral disease usually affecting myopic women
• Presentation - fourth to fifth decade of life. Blurring of central vision ± photopsia (seeing flashing lights).
• Investigations - fluorescein angiogram
• Treatment - in certain cases, patients may be amenable to laser photocoagulation, systemic steroid or surgery (where
  neovascular membranes are excised)
• Prognosis - reasonable if the lesions do not involve the macula

Multifocal choroiditis

• Nature - uncommon, recurrent disease which is usually bilateral and associated with a panuveitis. Its aetiology is not clearly identified but the Epstein-Barr virus may have a role.
• Presentation - fourth decade (female:male = 3:1) with blurring of vision, floaters and photopsia
• Investigations - fluorescein angiogram
• Treatment - systemic steroids have been shown to be effective in at least 50% of cases. Immunosuppressive agents are also used in order to reduce the amount of systemic steroids required long-term. Some patients may also benefit from laser photocoagulation.
• Prognosis - this condition recurs over months and frequent foveal involvement gives rise to a relatively poor prognosis.

Multiple evanescent white dot syndrome (MEWDS)

• Nature - uncommon, idiopathic and self-limiting condition. It is usually unilateral.
• Presentation - third to fifth decade, more often in females than males (4:1). The patient complains of decreased vision and photopsia, most often in the temporal visual field.
• Investigations - fluorescein angiogram
• Treatment - none
• Prognosis - full recovery after a few weeks

• Nature - these are parallel grooves involving the Bruch's membrane. When looking at them on fundoscopy, they give the impression of a sheet of clingfilm that is being pulled taught centrally around the disc. There are a number of causes including orbital disease (such as retrobulbar tumours), choroidal tumours, ocular hypotony (following significant surgery) and a number of other miscellaneous causes (idiopathic, chronic papilloedema and posterior scleritis).
• Presentation - many patients are asymptomatic but they may complain of metamorphopsia or impaired vision over time
• Investigations - fluorescein angiogram
• Treatment - this depends on the underlying cause but asymptomatic folds do not require treatment
• Prognosis - this depends on the underlying cause

• Nature - the choroid detaches from the underlying sclera with accumulation of serum-like fluid or blood. It can occur as a result of trauma (including eye surgery), globe hypotony of any aetiology, inflammation or an increase in transmural pressure. More unusually, a choroidal detachment can occur on doing the Valsalva manoeuvre or spontaneously.
• Presentation - photopsia and floaters. Where there is a large detachment, there may be a visual field defect. Pain is not generally a feature unless it is a post-operative haemorrhagic detachment in which case excruciating pain and sudden loss of vision occur (these are almost pathognomic symptoms).
• Investigations - it is diagnosed on examination of the fundus
• Treatment - as soon as the diagnosis is made, topical steroids, cycloplegics and mydriatics are given. Surgery follows depending on the nature of the detachment.
• Prognosis - this depends on the cause and extent of the detachment. Damage can occur anteriorly (corneal endothelial damage, anterior synechiae, lens opacities) and posteriorly(maculopathy). Chronic detachment can also lead to globe phthisis (where it wastes away). Haemorrhagic choroidal detachment is associated with greater morbidity and up to 40% of these patients experience loss of useful vision.

• Nature - this involves a break in the choroid, in Bruch's membrane and in the overlying pigment retinal epithelium. It occurs after blunt trauma and is four times more likely to occur as a result of a contrecoup injury as from direct trauma. There may be a single (25% of cases) or multiple areas involved and there will typically be haemorrhage and oedema initially which settle with time. A rupture can occur many years after the original insult.
• Presentation - men present more often than women (5:1), often between the ages of 20 and 40, with recent or old trauma. Patients may be asymptomatic but they may equally complain of decreased vision or of a paracentral scotoma.
• Investigations - the diagnosis is made on examination but there may be a need for ultrasound or CT / MRI investigations if additional injury is suspected. There may be a place for fluorescein angiography where the patient presents years later with complications such as the formation of a neovascular membrane.
• Treatment - most patients do well with conservative management. They will be monitored for about 5 years to assess for the formation of a neovascular membrane ± associated delayed bleeding.
• Prognosis - 15-30% of patients develop a recurring neovascular membrane that may lead to retinal detachment. However, if the fovea is not involved, patients with uncomplicated choroidal ruptures have a good chance of full recovery.