Steps to smooth out folds and striae

By Stefanie Petrou Binder MD

Heidelberg - If simple lifting of the corneal flap does not reduce folds and striae seen in association with LASIK procedures, then a combination of de-epithelialisation, stretching and suture fixation will, say German researchers.

"Although folds and striae are evident in refractive surgery, they rarely affect visual acuity. However, " said Thomas Kohnen MD, Frankfurt University Eye Clinic. Dr Kohnen and colleagues analysed three individual cases presenting with folds. He reviewed the results at the annual meeting of the DGII (German-Speaking Organisation of Intraocular Lens Implantation and Refractive Surgery).

The first case study involved a 30-year-old male patient showing reticular flap folds at a four-month follow-up visit after a 2.5 D LASIK correction procedure. Visual acuity was 0.8 D and the patient experienced visual discomfort and monocular double vision. Confocal slit-scanning microscopic examination (ConfoScan P4, Tomey) revealed obvious fold formation in the central corneal epithelium and on Bowman's capsule. A simple lifting and rinsing of the flap was performed.

One month later, visual acuity improved to 1.0 D, but the patient still had the same subjective complaints. A second lifting was performed, disclosing additional corneal folds and no subjective improvement. The researchers concluded that a simple lifting of reticular folds was not sufficient in this case. A second case study involved an eye with postoperative visual acuity of 0.8 D, hyperopia of 1.5 D and astigmatism of -1/160° following a -7 D LASIK operation. Researchers located horizontal striae on the thinly cut flap.

In this case, simple flap lifting on the second postoperative day did not smooth out folds and microscopic evaluation revealed granulocyte deposits alongside newly formed folds. The next step was flap relifting, two months later, with debridement and rinsing with hyperosmolar solution to allow the flap to swell. Vision improved to 1.0 D and the horizontal striae disappeared in some areas. However, they were replaced by vertical striae elsewhere.

Furthermore, large-scale de-epithelialisation led to the development of diffuse lamellar keratitis. Although vision improved, the formation of new striae suggested to surgeons that a further step would be necessary to smooth out the flap more completely. The third case involved epithelial folds on the inner flap surface following LASIK.

On the first postoperative day, Grade 1 lamellar keratitis was observed along with horizontal folds. Flap relifting with rinsing was performed the next day and a contact lens fitted on the eye, as a means of applying even pressure. Visual acuity seven days later was 0.32 D, with widespread folds seen on the flap.

Ten weeks after the LASIK procedure, the surgeon relifted the flap with rinsing, debridement, stretching and suture fixation involving 10 buttonhole sutures. Although diffuse lamellar keratitis was observed as a result of debridement - which had reduced visual acuity to 0.25 D - best-corrected visual acuity was improved to 1.0 D. Interface haze was noted, involving active keratocytes, inflammatory infiltrate, and fibroblasts along the suture interface two months postoperatively. The folds were successfully treated.

Dr Kohnen noted that folds and striae could be treated to the point where they no longer reduce visual acuity if promptly and correctly dealt with. Although the simple lifting of a very thin flap led to the formation of new folds and striae, visual acuity was nonetheless improved. Flap re-lifting with de-epithelialisation, rinsing with hyperosmolar solution to gorge the tissues and suture fixation to stretch out the flap served to reduce folds and aid the improvement of visual acuity. Debridement carries with it the complication of diffuse lamellar keratitis.