Original Articles

Phototherapeutic keratectomy for Reis Bucklers’ corneal dystrophy Christopher Rogers, FRACO, FRACS Peter Cohen, FRACO, FRACS Michael Lawless, FRACO, FRACS

Abstract Superficial keratectomy, penetrating and lamellar keratoplasty have all been advocated when inter- vention in Reis Bucklers’ corneal dystrophy is necessary because of diminished visual acuity. In this study, 11 eyes were treated by phototherapeutic keratectomy with an excimer laser. Two eyes had previously been treated by penetrating keratoplasty. The visual acuity improved in all eyes, from an average of 6/60 to 619 with complete cessation of recurrent erosions. The technique was modified, with experience, to minimise the hyperopic shift that occurs with this procedure. Phototherapeutic keratectomy has significant advantages over other procedures and is now the procedure of choice once surgery is required in Reis Bucklers’ dystrophy.

Key words: Phototherapeutic keratectomy, Reis Bucklers’ corneal dystrophy.

Reis Bucklers’ corneal dystrophy is an autosomal dominantly inherited d i ~ e a s e . ’ , ~ , ~ It is detectable in early childhood although symptoms are not present until the teenage years. Symptoms are due to recurrent erosions followed by loss of visual a c ~ i t y , ~ but the severity of these is variable. The cornea progressively becomes cloudy with a grey- white reticular haze. Irregular astigmatism is associated with the corneal erosions. The opacities are diffuse and mainly at the level of Bowman’s membrane.

Histopathological studies show degenerative changes occur in the basal epithelial cells and the basement membrane is irregularly present. The main abnormality is fibrocellular connective tissue anterior to and replacing Bowman’s membrane.s,6 The fibrocellular connective tissue tends to project into the epithelial layer and it is these intraepithelial projections, together with variations in subepithelial scar tissue which account for the clinical appear- ance. Some patients will go through life requiring no more than occasional lubricants, ointments and patching, and with age, the severity and frequency of the recurrent erosions diminish. Near vision is often remarkably good despite compromised distance acuity.

When diminished vision is such that intervention is required, lamellar and penetrating keratoplasty have been the procedures of ~ h o i c e ~ ~ ~ ~ ’ with visual results better with the latter. Results are variable with lamellar keratoplasty and penetrating kera- toplasty exposes the patient to significant well known risks. The fact that the dystrophy recurs after both procedures multiplies these risks and limitation^.*^^^*^^ Superficial keratectomy has also been advocated, but the reported visual results are only

Phototherapeutic keratectomy (PTK) with the excimer laser has been used to treat a variety of superficial corneal including Reis Bucklers’ dystrophy.lS,l6

In this study, 11 consecutive eyes with Reis Bucklers’ dystrophy requiring intervention were

Sydney Refractive Surgery Centre, Mater Misercordiae Hospital, Rocklands Road, Crows Nest, Neui South Wales 2065, .4ustmlia. Reprints: Dr C Rogers, North Shore Medical Centre, 66 Pacific Highway, St Leonards, NSW 2065.

Phototherapeutic keratectomy for Reis Bucklers’ corneal dystrophy 247

treated by PTK. All eyes were treated between September 1991 and September 1992. The results of treatment of these eyes, with a follow-up of between two and 14 months, are reported.

Method and results Eleven eyes of eight patients, two of whom had had previous penetrating keratoplasties, were treated by PTK with a Summit Excimed 200 UVLA excimer laser 10 Hz with an ablation rate of 0.25 microns per pulse. All eyes had a preoperative best corrected acuity of between 6/36 and count fingers (Table 1).

Before surgery, several drops of amethocaine 0.5% and one drop of pilocarpine 2% were instilled. In Patient 2 (Table 2) the epithelium was removed with a blunt hockey blade. It was noticeable that the bed left after epithelial removal was very irregular. The room lights were dimmed and the cornea was then ablated with a 5.00 mm PTK until the blue fluorescence disappeared, and then for another 70 pulses. In the other 10 eyes, 0.5% hydroxymethylcellulose was placed on the cornea and a 5.00 mm PTK was performed. The masking fluid and epithelium were ablated until the blue fluorescence disappeared. This required between 175 and 290 pulses with an average of 225 pulses. It is after disappearance of the blue fluorescence that the excimer laser is ablating Bowman’s membrane and corneal stroma. This remain- ing corneal bed was ablated with between 75 and 250 pulses (Table 2). After PTK, tobramycin 0.3% and cyclopentolate 1% drops were instilled and the eye padded. Patching was continued for three to four days. FML drops were used for up to two months, commencing three times a

Table 1. Age and visual acuity before surgery

Age Corrected VA before surgery Patient

(years)

1.

3. 4. 5. 6.* 7. t 8. t 9. i

10. 11.*

7 I.

19 28 18 43 21 20 52 43 18 23 21

6/60 6/36 CF

6/36 6136 6/60 6/60 6/60 CF 6/36 6/36

CF = count fingers; VA =visual acuity. +Second eye. tI’revious penetrating keratoplasty.

Table 2. Laser pulses applied and hyperopic shift

Pulses through Pulses blue after Hyperopic Shift (dioptres)

~ ~ ~~ ~

1. 175 75 1.00 0.50 0.50 2. Manual+ 70 0.50 0.25 0.25 3. 250 150 1.75 2.00 4. 210 250 8.00 7.00 5. 290 220 3.5 3.25 6. 220 240 6.00 4.50 7.* 225 180 2.00 2.00 8.* 250 175 6.50 5.25 9. 240 150 0.75

10. 225 170 1.50 11. 170 220 3.75

*Previous penetrating keratoplasty

day and gradually reducing. It was noticeable that, with one exception, the patients had less discomfort than patients undergoing PRK for myopia.

Patient 1 was treated with 75 pulses. This left some residual corneal opacity and at one month the best corrected visual acuity was only 6/12 - 2. After this progressively more pulses were applied and in Patient 4, 250 pulses were applied after disap- pearance of the blue fluorescence. This cornea looked very clear at the slit-lamp examination after the procedure, with no apparent residual opacity. However, the hyperopic shift was 8.0 dioptres which has regressed to 7.0 dioptres at six months. Since then the number of pulses applied has gradually been reduced and the hyperopic shift significantly diminished.

Patient 1 at 12 months had improved from 6/12 - 2 to 6/9. Best corrected visual acuity after PTK was, at last follow-up, between 6/6 and 6/12 for all patients (Table 3). No patients have had recurrent erosions since the procedure.

Eight eyes that had not had previous keratoplasty were treated with an intact epithelium. A striking feature is the minor astigmatism after PTK (average 1.22 dioptres) occurring in these eyes. The patient who had manual removal of the epithelium has 6.0 dioptres of astigmatism.

Discussion PTK is a safe, simple and effective method of treating Reis Bucklers’ corneal dystrophy. The visual results are good and to this stage there has been complete cessation of recurrent erosions. Patients have no difficulty fixing during the

248 Australian and New Zealand Journal of Ophthalmology 1993; 21(4)

Table 3. Postoperative visual acuity and refraction

Visual acuity Patient

Uncorrected

1. 6/12 2. 6/18 3. 6/12 4. 6/60 5. 6/18 6. 6/24 7. t 6/36 8. t 6/60 9. 619

10. 6/12 11. 6/24

Last refraction

- 0.251 + 0.75 - 3.50/+ 6.00 + 2.25 + 5.001 + 2.00 + 1.75/+ 1.50 +2.50/+ 1.50 + 2.00/+ 3.50 + 12.00/+ 1.00 + 0.50 + 0.251 + 1 S O +0.75/+ 2.50

Corrected

619 619 616 619 6/12 6/12 6/12 619 616 6/6 6/12

*Postoperative tPrevious penetrating keratoplasty.

procedure despite their poor preoperative acuity. PTK is much safer than penetrating keratoplasty. The refractive errors are more acceptable and the corrected visual acuities comparable to penetrating keratoplasty and superior to lamellar keratoplasty. It remains to be seen whether there will be recur- rence of the dystrophy after PTK, but even if this occurs management should be straightforward as the eye has not been compromised.

McDonnell and Sei leP described two cases of Reis Bucklers’ dystrophy treated by PTK without masking fluid. The results were good. Whether masking fluid does create a smoother surface for the excimer laser to work on and a consequently better result with less irregular astigmatism is not certain at this stage.

Figure 1 Reis Bucklers’ dystrophy.

Figure 2 Patient 4, two months after phototherapeutic keratectomy .

Figure 3 Patient 11, six weeks afrer phototherapeutic keratectomy. Note the central corneal flattening.

Wood et al. lo and Schwartz and Taylor” reported superficial keratectomy as a treatment for Reis Bucklers’ dystrophy. While effective, the reported visual improvement was not large and in those cases where it was recorded there was a significant increase in astigmatism. There has been no long- term follow-up reported to determine whether the dystrophy recurs after superficial keratectomy.

In summary, this series indicates that PTK is the treatment of choice in Reis Bucklers’ dystrophy. The technique has been modified with experience. The temptation to achieve a perfect slit-lamp appea- rance should be resisted, since this leads to consider- able hyperopic shift. The visual acuities of patients with a small amount of residual opacity are good. The number of pulses that should be applied to Bowman’s membrane and corneal stroma is uncer- tain, but is probably between 75 and 175 pulses.

Phototherapeutic keratectomy for Reis Bucklers’ corneal dystrophy 249

This gives an acceptable slit-lamp appearance, corrected acuity of 616 to 6112 with a hyperopic shift of less than 2.0 dioptres and minor associated astigmatism.

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The Editor would like to acknowledge and thank the following reviewers for their specialised contribution to reviewing articles submitted to the Australian and New Zealand Journal of Ophthalmology during 1993.

Dr Deb Colville (VIC) Dr Geoffrey Crawford (WA) Dr John Crompton (SA) Dr James Elder (VIC) Dr Lye Pheng Fong (VIC) Dr Ivan Goldberg (NSW)

Dr Wilson Heriot (VIC) Dr John McKenzie (VIC) Dr Lawrence Sullivan (VIC) Dr Tim Sullivan (QLD) Dr Hugh Taylor (VIC)

250 Australian and New Zealand Journal of Ophthalmology 1993; 21(4)