World Rare Disease Day: shedding light on rare eye diseases to encourage better understanding, awareness and hope

Meesmann corneal dystrophy 

 A rare genetic disorder characterised by the abnormal formation of tiny cysts or vesicles within the corneal epithelium (the outermost layer of the cornea), Meesmann dystrophy typically presents with symptoms such as blurred vision, discomfort, foreign body sensation and occasionally, recurrent corneal erosions.  

You can read more about WRDD ambassador, Noah’s experience with Meesmann Dystrophy here.

Behçet's disease 

Behçet's disease is a rare autoimmune disorder characterised by inflammation of blood vessels throughout the body. The eyes are commonly affected in Behçet's disease and ocular involvement can lead to significant complications.  

• Uveitis, or inflammation of the uvea (the middle layer of the eye), is one of the most common ocular manifestations of Behçet's disease. Uveitis can cause eye pain, redness, blurred vision, sensitivity to light (photophobia) and floaters 
• Inflammation of the blood vessels in the retina (retinal vasculitis) is another common ocular complication of Behçet's disease. It can lead to retinal haemorrhages, vascular occlusions (blockage of a blood vessel) and ischemia (diminished blood supply to eye tissue), which may result in vision loss or even blindness if left untreated 
• Inflammation of the conjunctiva, the thin membrane covering the white part of the eye, can occur in Behçet's disease. Conjunctivitis may cause eye redness, irritation, discharge and discomfort 
• Inflammation of the cornea (keratitis) can occur in Behçet's disease, leading to symptoms such as eye pain, blurred vision, photophobia and tearing 
• Inflammation of the optic nerve (optic neuritis) can occur in Behçet's disease, resulting in vision loss, changes in colour vision and pain with eye movement

Conjunctival malignant melanoma 

While melanoma is most associated with the skin, it can also manifest in the eyes. Conjunctival malignant melanoma is a rare and aggressive form of eye cancer that originates in the conjunctiva, the thin, transparent membrane covering the white part of the eye.  

Conjunctival melanoma typically presents as a pigmented or non-pigmented mass on the surface of the eye. This growth may appear raised or flat and can vary in size and colour. In some cases, the tumour may be mistaken for a benign lesion such as a nevus (mole) or a pinguecula (yellowish bump). 

A conjunctival melanoma tumour can interfere with normal vision by obstructing the visual axis or causing irregular astigmatism. Depending on the location and size of the tumour, individuals may experience blurred vision, distorted vision or visual field defects. 

Conjunctival melanoma can cause irritation, redness and discomfort in the affected eye. Patients may experience a sensation of grittiness, foreign body sensation or persistent itching. The presence of the tumour may also lead to excessive tearing (epiphora) or dryness of the eyes. 

If left untreated, conjunctival malignant melanoma has the potential to invade nearby structures within the eye, such as the cornea, sclera, or even the orbit (eye socket). Moreover, malignant melanoma can metastasise (spread) to other parts of the body, including the lymph nodes, liver, lungs and brain, which can significantly worsen the prognosis. 

Early detection and treatment are crucial for managing this condition and preventing its spread.

Optic disc pit 

A congenital condition that involves a small defect in the optic nerve head, optic disc pits can lead to fluid accumulation and subsequent damage to the macula, the central part of the retina responsible for sharp, central vision.  

Individuals with optic disc pit may experience a range of other visual symptoms, which include: 

• Blurred or distorted central vision, metamorphopsia (perception of distorted images), micropsia (objects appearing smaller than they are) and scotomas (blind spots) 
• Peripheral vision loss, which can further impact activities such as driving, navigating obstacles and detecting motion in the peripheral visual field 
• An increased risk of retinal detachment, a sight-threatening condition where the retina pulls away from its underlying tissue. Retinal detachment can lead to sudden and severe vision loss if not promptly treated

TINU syndrome (tubulointerstitial nephritis and uveitis)  

TINU syndrome is a rare disorder characterised by inflammation of the kidneys (tubulointerstitial nephritis) and the eyes (uveitis). While the exact cause remains unknown, it is believed to involve an abnormal immune response. Patients may experience symptoms such as eye pain, eye redness, and changes in urine colour, highlighting the importance of comprehensive evaluation and multidisciplinary care.