Case of the Month: July 2015

Written by Dr James Wong

A 53 yr old Asian female presented to the clinic with a 1 month history of central distortion, as well as long-standing blurry vision in the right eye. Her left vision was unaffected. She also complained of dry eyes.

Her general health history included osteoarthritis and gout but she was otherwise well with no diabetes, hypertension or hypercholesterolemia. She had never smoked and did not consume any alcohol. She had no known family history of particular ocular disorders.

On clinical examination, best corrected visual acuity was 6/12 in the right eye and 6/6 in the left. Intraocular pressures were within limits. She had mild dry eyes. All other anterior segment findings were normal.

Dilated fundus exam found angioid-streaks in both eyes (blue arrows Fig 1 and 2). There was also a mottling of the peripheral retina resembling the ‘skin of an orange,’ known as peau d’orange (green arrow Fig 1). There was thickening and hard exudates at her right macula (red arrow Fig 1.)

Figure 1

Figure 1

Figure 2

Figure 2

Figure 3

Figure 3: An OCT scan of her right eye revealed subretinal and intraretinal fluid

Figure 4

Figure 4: Left eye Macula was dry

Figure 5

Figure 5: Fundus Fluroescein and Indocyanine angiography found active bleeding from a choroidal neovascularization near the macula in the right eye

The Diagnosis: Right eye choroidal neovascularisation (CNV) secondary to angioid streaks, a form of wet macular degeneration.

The patient was started on a strict 1 monthly intravitreal anti-VEGF injections in the right eye to clear the subretinal fluid (SRF).

Figure 6

Figure 6: OCT scan shows SRF gradually decreasing with each injection

The vision in the right eye correspondingly also improved to 6/9.5 after 3 injections.

Long term management is required. As the fluid clears, the injection interval may be extended. However, if CNV remains active then monthly injections will be necessary to preserve vision.

The patient was also referred to a Dermatologist for a consult on the possibility of her angioid streaks being associated with a skin condition called pseudoxanthoma elasticum.

 

Discussion

Noted by Doyne in 1889, Angioid streaks are irregular crack-like lines in the retina, formed in a circulating manner from the optic disc. It occurs as a result of a weakened Bruch’s membrane and usually affects both eyes. People can remain unaware that they have this condition for years until a secondary complication such as CNV arises from a streak causing vision loss and distortion.

Angioid streaks are linked with many systemic conditions, the most common being pseudoxanthoma elasticum (PXE).

PXE is a rare hereditary disorder that causes calcium to accumulate in certain elastic tissues in the body, leading to mineralisation and breaking up of those tissues. Research has shown that it is due to mutations of the ABCC6 gene.

This usually affects the:

  • Cardiovascular system: contributing to atherosclerosis, low pulse rates in the extremities, cardiomyopathy etc.
  • Skin: cobblestone appearance of the skin, usually on the neck. A skin biopsy is needed to confirm diagnosis.
  • Eyes: anatomical mottled appearance of the retinal pigment epithelium known as “peau d’orange.” There may also be angioid streaks that may lead to active bleeding within the retina.

Other systemic associations to angioid streaks include Ehlers-Danlos syndrome, Paget’s disease, Sickle cell disease/hemoglobinopathies. In some cases, angioid streaks are idiopathic.

This case study is a good example of clinical symptoms affecting the eyes, which can then become a possible link to identifying other systemic conditions.

 

Doyne, R: Choroidal and retinal changes the result of blows on the eyes. Trans Ophthalmol Soc UK 1889; 9: 12