EDTA Chelation For Symptomatic Band Keratopathy: Results and Recurrence

Design

Retrospective, single-center, observational, cohort study

N= 72 patients (89 eyes)

Objective

To identify causes of symptomatic band keratopathy, and assess the results and long-term recurrence rates following chelation with topical ethylene-diamine-tetra-acetic acid (EDTA)

Study Groups

Inclusion Criteria

Exclusion Criteria

Methods

This was a retrospective review of patients who underwent EDTA chelation for band keratopathy at a single center in Scotland. All patients received a topical anesthetic before a lid speculum inserted in the theater. A solution of 20% alcohol was applied to the cornea within a LASIK well for 40 seconds and the epithelium was removed. EDTA (in the form of disodium edetate 0.37% eye drops) was applied to the surface for 3-minute intervals and the loosened calcium deposits were debrided with a curved blade. A bandage contact lens was placed at the end of the procedure, and preservative-free dexamethasone 0.1% and chloramphenicol 0.5% drops were prescribed for the post-operative period.

Duration

2009 to 2015

Outcome Measures

Improvement or worsening of visual acuity at a 4-week follow-up; change of ≥2 lines of Snellen visual acuity; recurrence

Baseline Characteristics

EDTA (n= 89 eyes)

Age, years (range)

Eye:

Right

Left

41 (46%)

48 (54%)

Cause of band keratopathy:

Idiopathic

Glaucoma/ocular hypertension

Retinal detachment

Phthisis/hypotony

32 (36%)

24 (27%)

7 (8%)

6 (7%)

Mean operation duration, minutes (range)

20 (10-45)

Median follow-up duration for recurrence, days

374

Results

EDTA (n= 89 eyes)

Clear visual axis at a 4-week follow-up

Maintained or improved visual acuity

Improved by ≥2 lines

71 (79.8%)

12 (13.5%)

Recurrence

25 (28.1%)

Even though most patients had stable or improved visual acuity, there was no evidence of a difference between the initial and final visual acuity following treatment (p= 0.441).

Although 25 eyes showed localized recurrence of calcium with a mean time of 546 days (median 374), only four cases (4.5%) required repeat EDTA chelation.

Adverse Events

Study Author Conclusions

Chelation of calcium with topical EDTA is a safe and effective treatment for band keratopathy. Visual acuity improves in most eyes and while the rate of recurrence is moderate, the need for retreatment is low (4.5% overall).

InpharmD Researcher Critique

EDTA Chelation for Calcific Band Keratopathy: Results and Long-term Follow-up

Design

Retrospective, single-center, observational, cohort study

N= 54 patients (65 eyes)

Objective

To determine the etiologies and management of calcific band keratopathy (CBK), and assess the results and long-term follow-up after ethylenediamine-tetraacetic acid (EDTA) chelation

Study Groups

Baseline visual acuity:

<20/400 (n= 11)

20/400 to 20/200 (n= 17)

20/100 to 20/50 (n= 14)

≥20/40 (n= 9)

Inclusion Criteria

Exclusion Criteria

Methods

This was a retrospective chart review of patients with band keratopathy treated with EDTA chelation at a single center in Philadelphia. EDTA chelation was performed at the slit lamp by one of three attending physicians. A 3.75% dilution of disodium EDTA (three parts normal saline:one part 15% [150 mg/ml] Endrate) was prepared in a tuberculin syringe. Topical proparacaine drops were instilled and a lid speculum was inserted. The epithelium overlying the band keratopathy was removed with a blade or with a sterile cotton-tipped applicator.

A cellulose sponge or a sterile cotton applicator was soaked in the diluted EDTA solution and rubbed against the calcium until its dissolution. This required from 5 to 45 minutes of EDTA application, depending on the density of the calcium. At the end of the procedure, a cycloplegic drop (e.g., cyclopentolate 1% or scopolamine 0.25%) was instilled and an antibiotic ointment (e.g., erythromycin or bacitracin) was applied to the eye, which was patched.

All patients were examined on the following day; frequent use of antibiotic ointment was prescribed, and patients were reexamined every few days until the epithelial defect healed completely. Further follow-up examinations were performed at 1 week, 1 month, and various intervals thereafter.

Duration

January 1996 to July 2002

The mean follow-up time was 36.6 ± 68.9 months (range: 1 to 335 months)

Outcome Measures

Baseline Characteristics

EDTA chelation (N= 54; 65 eyes)

Age, years (range)

Female

Central band keratopathy, eyes

Baseline visual acuity

<20/400 (n= 11)

20/400 to 20/200 (n= 17)

20/100 to 20/50 (n= 14)

≥20/40 (n= 9)

11/51 (21.6%)

17/51 (33.3%)

14/51 (27.5%)

9/51 (17.6%)

Nine patients were lost to follow-up, leaving 51 eyes for analysis.

Results

All eyes (n= 51)

Number of lines of visual improvement at last follow-up

-2

-1, 0, +1

+2, +3

+≥4

7.8%

56.9%

5.9%

29.4%

Recurrence

10/56 (17.8%)

Forty-four of 45 patients (98%) reported partial or complete resolution of their symptoms after EDTA chelation. Those with partial relief were successfully treated with preservative-free artificial tears and lubricating ointment.

The mean time to recurrence was 17.7 years (range: 1 month to 26 years). The highest number of recurrences was in 3 of 5 eyes with uveitis (60%; p= 0.03).

<20/400 (n= 11)

Visual acuity at follow-up

<20/400

20/400 to 20/200

20/100 to 20/50

≥20/40

9

3

0

1

0

3

0

0

2

10

10

0

0

1

4

8

Adverse Events

None reported

Study Author Conclusions

Chelation with EDTA is an effective treatment of CBK. Visual acuity improves most in eyes with acuity between 20/50 and 20/400. This treatment can be used as the initial surgical intervention after conservative measures fail.

InpharmD Researcher Critique

Limitations of this study are related to the retrospective, single-center aspect of the study. There is a possibility that some patients went to another clinic for follow-up, thus missing potential recurrences. Strengths of this study include the robust study population and long-term follow-up.

Combined Ethylenediaminetetraacetic Acid Chelation, Phototherapeutic Keratectomy and Amniotic Membrane Transplantation for Treatment of Band Keratopathy

Design

Retrospective, single-center, observational, cohort study

N= 10 patients (11 eyes)

Objective

To evaluate the therapeutic efficacy of ethylenediaminetetraacetic acid (EDTA) chelation and excimer laser phototherapeutic keratectomy (PTK) combined with amniotic membrane transplantation (AMT) for the treatment of band keratopathy (BK)

Study Groups

Inclusion Criteria

Patients with band keratopathy involving the anterior stroma who underwent EDTA chelation and excimer laser PTK combined with AMT; were followed for at least 6 months

Exclusion Criteria

Methods

This was a retrospective review of 10 patients who underwent combined EDTA chelation and amniotic membrane transplantation at a single center in Korea. After instillation of topical proparacaine, the corneal epithelium overlying calcium plaques were removed with a spatula or cotton-tipped applicator. A cellulose sponge soaked in EDTA (0.05 M) was applied to the band for 3 to 5 minutes, depending on the density of the calcium. After the EDTA had adequately infiltrated into the lesion, the calcium deposits were rubbed off.

Excimer laser PTK was performed to remove remaining calcium plaques in the anterior stroma after EDTA chelation using a Technolas 217z Zyopticx™ excimer laser system with an average energy density of 120 mJ/cm² and a pulse repetition rate of 50 Hz. The central ablation zone was 7.0-7.5 mm in diameter and 40-50 µm in depth, depending on the extent of the lesion. After central ablation, the peripheral cornea was ablated with a diameter of 2.0 mm for removal of the remaining calcium deposits.

EDTA chelation and excimer laser PTK were followed by AMT. Under local anesthesia, the preserved amniotic membrane (AM) was cut to approximately 8.0 mm in diameter using a trephine blade and was placed over the epithelial defect as a graft, with the stromal side facing down. The AM was fixed onto the corneal surface using fibrin glue. Postoperatively, all patients were treated with topical ofloxacin and fluorometholone eyedrops four times per day and hyaluronic acid frequently until epithelialization was complete and the ocular surface was stable.

Follow-up examinations were performed daily for 2 weeks postoperatively, and thereafter at 1-2 week intervals. 

Duration

2003 to 2007

Outcome Measures

Results

Associated Conditions

Pre-treatment BCVA

Postoperatively, the best corrected visual acuity remained unchanged in eight eyes (72.7%) and improved in three eyes (27.3%). There was no significant difference between the preoperative and postoperative best corrected visual acuities (p= 0.11). Calcium plaques were removed completely in all cases.

The mean time for complete healing of the cornea was 10.6±5.3 days after surgery.

Adverse Events

No patients experienced any complications or recurrence.

Study Author Conclusions

The combination of EDTA chelation, phototherapeutic keratectomy, and amniotic membrane transplantation is safe and effective for the treatment of band keratopathy.

InpharmD Researcher Critique

Simplified, Readily Available Method For the Treatment of Band Keratopathy With Ethylenediaminetetraacetic Acid

Design

Case series

N= 5 patients (6 eyes)

Objective

To compare 3 methods for creating ethylenediaminetetraacetic acid (EDTA) solution using readily available Vacutainer tubes for the treatment of band keratopathy

Study Groups

Method 3 (N= 5 patients)

Inclusion Criteria

Exclusion Criteria

None reported

Methods

Three different methods of EDTA preparation were compared in this study. Each method was repeated 10 times for osmolarity analysis. Method 3 had the best characteristics for clinical use, and it was used in five patients who gave informed consent.

Method 1: 0.3 mL of sterile water was injected into a purple-topped 3-mL K₂EDTA Vacutainer blood collection tube containing 5.4 mg of K₂EDTA. The diluent was swirled to dissolve the K₂EDTA coating the inside of the tube. The solution was then transferred from tube to tube, and the process was repeated for 5 tubes.

Method 2: 0.3 mL of sterile water was injected into a single 10-mL K₂EDTA Vacutainer blood collection tube containing 18 mg of K₂-EDTA. The tube was swirled to dissolve the K₂EDTA.

Method 3: 0.3 mL of sterile water was injected into the 10-mL K₂EDTA tube containing 18 mg of K₂EDTA, then a sterile, dry cotton-tipped applicator was used to absorb the fluid in the tube before then sweeping along the entire interior surface of the tube to dissolve the K₂EDTA coating the inside.

Duration

Outcome Measures

Baseline Characteristics

Method 1

Method 2

Method 3

Control 3% EDTA solution

Osmolarity, mOsm/L

Concentration, mg/mL

Preparation time, seconds

Results

All patients treated with method 3 experienced no complications and no delayed healing.

Adverse Events

None reported

Study Author Conclusions

Method 3 using a single 10-mL Vacutainer tube with 18 mg of K2-EDTA had the best balance of effective concentration of EDTA, time to preparation, and simplicity of methodology, when compared with previously published methods 1 and 2. It also yielded a greater final volume of solution.

InpharmD Researcher Critique

This study mainly assessed extemporaneous EDTA solution preparation. The results favored the third method, which was used to treat 5 patients (6 eyes). The authors found the solution's clinical effectiveness indistinguishable from previous clinical experience with method 1.