Xử trí bệnh GIÁC MẠC DẢI BĂNG bằng phương pháp EDTA chelation - Band Keratopathy EDTA chelation

This video shows an eye with significant cornea band keratopathy, and how it is removed with EDTA chelation.

About this condition
Band Keratopathy, is a precipitation of calcium salts that forms under the epithelium. It occurs in a band pattern across the middle cornea that is most exposed to air. The believe is that evaporation of tears allows calcium and phosphate to increase in concentration and precipitate in this intrapalpebral space.

Now … why doesn’t EVERYONE get band keratopathy? We believe that elevation of the surface pH level, which occurs with conditions such as chronic inflammation, may change the calcium solubility and lead to high rates of precipitation. This theory is supported by the fact that these calcium bands don’t go all the way to the limbus because the limbal blood circulation here has a buffering effect on pH.

On exam, you can see a layer of white material or plaques at the level of bowmans layer and even in the anterior stroma. You can sometimes see small round holes in this plaque which are where corneal nerves break through bowman’s membrane on their way up to the epithelium.

If sparse, band keratopathy may go unnoticed by the patient. However, with extensive deposition in the visual axis, acuity can be affected. Also, epithelial cells don’t stick down well to calcium plaques and these patients can have recurrent corneal erosions and discomfort. Vision and comfort are both reasons to consider a surgery.

Debridement:
Calcium can be removed (like in this video) in a minor procedure room. After anesthetizing the eye, the cornea is bathed with 2% EDTA solution. This solution can be applied using Weck-cel sponges or by using a funnel to bath the cornea. The surface epithelium and underlying calcium is than scraped off using a blunt spatula or careful application of a curved scalpel. Small deposits remove easily, but larger plaques can be tenacious requiring 30 minutes or more of additional chelation/scraping. The goal is to clear the central visual axis.

An excimer laser can be used to polish the underlying cornea if significant irregularities exist. However, you definitely DON’T want to use that laser to remove the calcium … the laser will preferentially remove stroma and you’ll end up with significant irregular astigmatism.

Potential Ocular Associations with Band Keratopathy

Chronic Uveitis
JRA
Phtisis
End stage glaucoma
Topical steroid (with phosphate)
Pilocarpine with mercury based preservatives
Silicone Oil
Intraocular tPA

If a patient presents to you with no signs of ocular cause, consider drawing a serum calcium, phosphate, parathyroid, and sarcoid labs (ACE, lysosyme).

Systemic diseases associated with high calcium

Paget disease
Hyperparathyroidism
Vitamin D excess
Kidney Failure
Sarcoidosis
High Phosphate

Tìm hiểu thêm phương pháp ĐÁNH GIÁ PHƯƠNG PHÁP GỌT GIÁC MẠC BẰNG LASER TRONG ĐIỀU TRỊ BỆNH LÝ GIÁC MẠC DẢI BĂNG : http://khaosat.yds.edu.vn/tcyh/upload/2009/Mat%20-TMH/16.pdf