West African Crystalline Retinopathy

From EyeWiki




Disease Entity

West African Crystalline Maculopathy(WACM)

Disease

West African Crystalline Maculopathy is an asymptomatic, asymmetric, bilateral crystalline maculopathy characterized by focal depositions of birefringent yellow green crystals in the fovea. It was first described by David Sarraf et. al. in 2003 among 6 elderly from the Igbo tribe of southeast Nigeria. [1]

Etiology

The etiology remains unknown. Several factors have been postulated, including chloroquine treatment and kola nut intake.

General Pathology

There are many hypotheses regarding the genesis of these crystals, notably that there is a break down of the blood retinal barrier facilitating the entry of innately or environmentally derived crystals.

Primary prevention

There is currently no preventive measure for this disease.

Diagnosis

West African Crystalline Maculopathy is a diagnosis of exclusion, based on the clinical appearance of the foveal crystals in a west African patient.

History

Pertinent points to be considered are the presenting age of the patient, West African origin, and dietary habits with regard to intake of kola nuts. Medical history is important including treatment for malaria and medication history with use of chloroquine, canthaxanthine, tamoxifen and nitrofurantoin. History of prior ocular surgery, retinal detachment or any systemic diseases especially renal disease should also be taken. History regarding pre existing ocular disease especially retinal vascular disease or inflammatory disease is also important.

Physical examination

A thorough ophthalmological examination including ocular surface examination, anterior and posterior segment evaluation should be done. Visual acuity typically remains unaffected. Fundus biomicroscopy reveals clusters of yellow- green crystals in the foveal region. Features of pre existing diseases like those of diabetic retinopathy and retinal vascular occlusions may be present. Additionally, both color vision tests and Humphrey visual field tests remain normal.

Symptoms

West African Crystalline Maculopathy is usually asymptomatic. A decrease in vision may be observed as a consequence to retinal vascular diseases involving the macula which may be associated with the crystalline maculopathy.

Diagnostic procedures

Optical coherence tomography (OCT) plays a critical role in the diagnosis of WACM. Bilateral asymmetric intra retinal refractile deposits in the foveal region can be appreciated using high resolution OCT. Some studies have localized the crystals to the inner retinal layers while others have localized the crystals to Henle's layer. Cystic fluid in the macular region can be present as a sign of associated diseases. Fundus fluorescein angiography (FFA) is usually unremarkable. Electrophysiological tests are also usually normal.

Differential diagnosis

Differential diagnosis of crystalline maculopathy

Systemic disease -

  • Oxalosis
  • Cystinosis
  • Hyperornithinaemia
  • Sjogren-larson syndrome

Drug induced-

  • Talc
  • Tamoifen
  • Canthaxanthine
  • Nitrofurantoin
  • Methoxyflorone

Ocular pathology-

  • Idiopathic parafoveal telengiectasis
  • Beitti's crystalline dystrophy
  • Calcified macular drusen
  • Chronic retinal detachment

Management

Complications

West african crystalline maculopathy is a unique form of crystalline maculopathy that is asymptomatic and has no sequelae.

Prognosis

The prognosis for this disease is good as it is not known to cause visual impairment.

References

  1. Sarraf D, Ceron O, Rasheed K, Drenser KA, Casey R. West African crystalline maculopathy. Arch Ophthalmol. 2003;121(3):338-342. doi:10.1001/archopht.121.3.338