Hemi-Automated Lamellar Keratoplasty (HALK)

Leonard Yuen, MD MPH MRCOphth Jodhbir Mehta, FRCS FRCOphth

Li Lim, FRCOphthDonald Tan, FRCS FRCOphth

SINGAPORE NATIONAL EYE CENTRE (SNEC)

The authors have no financial interest in the subject matter of this poster

Purpose

To describe a novel hybrid technique for anterior lamellar keratoplasty in corneas

with topographical irregularities

The advantages of Anterior lamellar keratoplasty (ALK) is its lower rejection rate and greater trauma resistance compared to PK, together with a reduced risk of endophthalmitis and expulsive haemorrhage. It is technically more demanding and time consuming, however techniques are constantly evolving with increasingly better outcomes.

Microkeratome-assisted lamellar keratoplasty is a well-described technique to prepare both recipient and donor beds which reduces the surgical time and allows the preparation of a smooth graft interface. However corneas with significant topographical abnormalities, areas of elevation or thinning, will be reproduced by the microkeratome when creating the recipient flap. It is therefore limited to patients who have stromal pathologies in the anterior-mid stroma and with regular corneal topographies.

Method

• Hemi-Automated Lamellar Keratoplasty (HALK), a combined procedure of manual recipient bed lamellar dissection with an automated donor preparation, was performed on 11 eyes of 11 patients with heterogenous causes of anterior stromal scarring

• All 11 eyes had a minimum of 4 months follow up, with a mean of 9 months (median 8, range, 4 – 12 months)

* A subset of 5 eyes had longer follow up of >12 months, with a mean of 19 months (median 17, range, 13-26 months)

DemographicsGender Date of Surgery Race Age Indication

1 Female 1.Nov.07 Indian 7 Congenital linear corneal scar

2 Male 3.Nov.07 Vietnamese 8 Scar from penetrating injury

3 Female 31.Jul.07 Chinese 19 Contact lens keratitis scar (pseduomonas)

4 Female 31.May.08 Chinese 10 Post excision of Iris-cornea tumor

5 Female 9.Jun.08 Chinese 40 Herpetic disciform keratitis

6 Male 20.Oct.08 Chinese 22 Contact lens keratitis scar

7 Male 2.Jan.09 Malay 44 Lattice dystrophy

8 Male 12.Jan.09 Indian 48 Deep traumatic stromal scar

9 Male 30.Jun.09 Chinese 22 Contact lens keratitis scar

10 Male 11.Jul.09 Indian 21 Contact lens keratitis scar (pseduomonas)

11 Male 13.Jul.09 Chinese 60 Corneal abscess scar

Mean age 27.4 years Median 22 (range, 7 – 60)

Results

Preoperative Postoperative P - value

Uncorrected Visual Acuity (UCVA, logMAR)

1.23 +/- 0.67[20/200]*

0.65 +/- 0.28[20/90]* 0.02

Best Corrected Visual Acuity (BCVA, logMAR)

0.75 +/- 0.63[20/110]*

0.39 +/- 0.23[20/50]* 0.10

Sphere (D) 0.89 +/- 4.41 1.66 +/- 2.72 0.65

Cylinder (D) -3.42 +/- 2.79 -3.34 +/- 1.53 0.94

MRSE (D) -0.82 +/- 3.95 0.01 +/- 2.76 0.61

N = 11, mean follow-up time 9 months

* Snellen Equivalent

Discussion

• Postoperative UCVA improved in 82% of eyes

• Postoperative BCVA improved in 64% of eyes– Mean Snellen BCVA achieved was 20/50 (range, 20/25 – 20/100),

comparable with other studies achieving 20/60 1 and 20/70 2 three months after conventional ALTK

• Postoperative SE was -0.01D– Values between -1.63 and -4.16D have been reported after PK 3,4,5,6

1.Vajpayee RB, Sharma N, Jhanju V, et al. One donor cornea for 3 recipients: a new concept for corneal transplantation surgery. Arch Ophthalmol. 2007 Apr;125(4):552-4.

2. Vajpayee RB, Vasudendra N, Tityal J et al. Automated lamellar therapeutic keratoplasty (ALTK) in the treatment of anterior to mid-stromal corneal pathologies. Acta Ophthalmol Scand. 2006: 84:771-773.

3. Watson SL, Ramsay A, Dart JKG, et al. Comparison of deep lamellar and penetrating keratoplasty in patients with keratoconus. Ophthalmology. 2004;111:1676-1682.

4. Panda A, Bageshwar LMS, Ray M, et al. Deep lamellar keratoplasty versus penetrating keratoplasty for corneal lesions. Cornea 1999;18:172-175.

5. Kirkness C, Ficker L, Steele AD, et al. The success of penetrating keratoplasty for keratoconus. Eye. 1990;4:673-688.

6. Buzard KA, Fundingsland BR. Corneal transplant for keratoconus results in early and late disease. J Cataract Refract Surg. 1997;23:398-406.

Discussion

In the subset of 5 eyes with>12months follow-up (mean 19 months):

– BCVA improves (p = 0.19)– UCVA improves (p = 0.06)

The continuing improvement of BCVA and UCVA over time may suggest corneal remodeling

DiscussionWhilst using donor tissue of less stringent quality than for PK, donor corneas previously discarded due to low endothelial cell count but clear good stroma can now be used, maximizing the use of the donor cornea

The mean postoperative pachymetry was 593 microns; a thicker postoperativecornea allows additional secondary corneal refractive procedures to be done to enhance visual outcomes

Conclusions

HALK is a novel procedure that forms another option in the armamentarium for the treatment of anterior stromal diseases

Early results are promising for a heterogenous group of corneal pathologies

The main advantages of HALK are:1. The uniform removal of anterior stromal pathology with

an irregular anterior corneal surface from the recipient2. The ability to customize the size and thickness of the

donor grafts resulting in optimal optical and postoperative outcomes