Posts Tagged ‘cornea’

Get an exam for cornea before you wear contact lenses

November 14th, 2009

Nowadays, through the technology of contact lenses has got an incredible improvement in test and diagnostic capabilities, still, contact lenses can damage contact lens wearers’ eyes in a complicate way.

Besides the basic testing measures such as refraction, cornea readings and corneal health evaluation, proper contact lens fitting and follow ups still need to take the corneal topography and endothelial cell count measurements into consideration. The corneal topography examines include the tests of the outer most layer to make sure whether the cornea irregularities, curves or pathology. The endothelial cell count examine the inner most layer, which is one cell layer. The number of cells per unit area and the quality of the cells are evaluated by the ECC, it said there are 2400 cells per unit area which are similar in color, shape and regimented. Once any change happened in the cell, the cell would die and leave a gap in its original position. The function of the endothelium is pump water out of the cornea. Once it gets some hurt, it will affect the corneal swelling, thickness, glare, and, of course, the ability of vision adjusting will decrease.

People who wear contact lenses should get an ECC to certain the function of the eyes is okay. Once find any abnormal situation, the wearers should make some changes in contact lens wearing.

The size and appearance of the cell in endothelial layer cause polymegathism, which means the ability of the endothelial cell to pump water from the cornea becomes weak. As a result, people get opacificrion, which also called cloudy cornea. Essentially, the changes are caused by the increase of lactate, the PH has changes, which decrease the cellular ATP and increase the endothelial hypoxia.

All of these are caused by contact lenses over wearing. The contact lenses not so fit the eyes brings about the endothelium overload, which makes the number of irregular cells increase. Some cells may be really abnormal.

People who get serious Polumegathism contact lens wear should stop wearing contact lens or reduce the time of wearing contact lens a lot, less than 10 hours per day. There exist highly permeable contact lenses which can allow enough oxygen to cornea.

People should do their best to avoid any corneal surgery which may cause endothelial cells loss. What is more, future cataract surgery may develop the technique to avoid losing of endothelial cells during the surgery.

In general, people who want to wear contact lenses should get an exam to make sure their cornea are totally healthy and do not put their frail eyes at risk.