Asteroid hyalosis :

Asteroid hyalosis is a degenerative condition of the eye involving small white opacities in the vitreous humourClinically, these opacities are quite refractile, giving the appearance of stars (or asteroids) shining in the night sky—except that ocular asteroids are often quite mobile. Ocular asteroids must be distinguished from the more common typical vitreous floaters, which are usually fibrillar or cellular condensates. 

The cause of asteroid hyalosis is unknown, but it has been associated with diabetes mellitus, hypertension, hypercholesterolemia

asteroid hyalosis is considered to be an age related change.

 The asteroid bodies are made up of hydroxylapatite, which in turn consists of calcium and phosphates or phospholipids. While asteroid hyalosis does not usually severely affect vision, the floating opacities can be quite annoying, and may interfere significantly with visualization and testing of the retina. 

While treatment of asteroid hyalosis is usually unnecessary, vitrectomy may occasionally be indicated, for both diagnostic and therapeutic purposes.

CORNEAL NEOVASCULARIZATION

Corneal neovascularization is abnormal blood vessel growth in the cornea from the limbus.

A normal, healthy cornea has no blood vessel growth. Blood vessels normally circle the cornea at the limbus, the junction of the clear cornea and the white part of the eye.

WHAT CAUSES CORNEAL NEOVASCULARIZATION?

• The main underlying cause is lack of oxygen to the cornea. 

• Long-term use of contact lenses 

• toxic contamination from lenses or solution

•  trauma or infection

•  chemical burns

• lens deposit buildup can also be a cause.

 When contact lenses or some other condition interferes with the transport of oxygen to the cornea, the eye responds by growing extra blood vessels to help supply oxygen and nutrients to the oxygen-depleted tissues. The longer a lens is worn (more than 10 hours a day), the greater the risk of corneal hypoxia (lack of oxygen) and the chance of developing corneal neovascularization. When blood vessels extend beyond 2mm from the margin of the cornea, the condition needs to be treated, or permanent intolerance to contact lens or vision loss can occur.

• Corneal neovascularization may also be caused by 
• infections, trauma to the eye,
•  chemical burns, 
• immune system diseases and certain other eye conditions, such as uveitis, glaucoma 

HOW IS CORNEAL NEOVASCULARIZATION DIAGNOSED?

Actively engorged blood vessels can be seen in the white of the eye. Other symptoms include the following:

• Pain

• Redness around the cornea

• Tearing

• Light sensitivity

• Decreased vision or blurring when wearing contact lenses

• Intolerance to contact lens after wearing them for a short time

HOW IS CORNEAL NEOVASCULARIZATION TREATED?

• Treatment of corneal neovascularization depends on the severity of the condition and the cause. Corticosteroids may be prescribed to reduce vascularisation. 

• Surgical options include laser photocoagulation.

•  Reduction or temporary cessation of contact lens wear time may be necessary to allow the tissues to heal.

•  A contact lens refit with an oxygen permeable or high oxygen transmissible lens is an option that works for many people

 Once the condition has healed, contact lens wearers should pay close attention to adequate corneal lubrication.