CORNEAL POCKETS

Intracorneal pockets created with femtosecond lasers have a wide variety of potential uses, said Ioannis G Pallikaris MD PhD, University of Crete, Heraklion, Greece. “Femtosecond lasers allow us to create corneal pockets safely and accurately with few complications and their versatility means that we have many new potential techniques to explore,” he reported at Femto 2013, an international meeting on anterior segment surgery.

Dr Pallikaris described his experience with the use of femtosecond lasers for creating intrastromal pockets for the placement of Flexivue Microlens (Presbia) presbyopic corneal inlays. He also described two new femtosecond laser techniques he and his team have developed, one for using an intrastromal pocket for delivering medicine and the other for placing a layer of biocompatible silicone to control corneal oedema in eyes with bullous keratopathy.

Focal points

The Flexivue Microlens is a doughnut-shaped hydrophilic polymer lens that is designed for implantation in the non-dominant eye. The inlay is 3.0mm in diameter and 20 μm in thickness. It is designed to provide two focal points, one for far vision and the other for near. Dr Pallikaris said that he uses the Intralase femtosecond laser (AMO) to create the pockets for the inlays. Using the system’s iPockets software, he creates the pockets at a depth of microns with width of 4.0mm. Thus far the results with the implants have been encouraging. In a study involving 45 patients who received the implant, the mean uncorrected near visual acuity improved from 20/100 to 20/25.

Although uncorrected distance visual acuity decreased in the operated eye, binocular uncorrected distance visual acuity remained unchanged. In addition, 92 per cent said they never used reading glasses. A more novel use of intrastromal pockets created with femtosecond lasers is to provide a means of delivery of medication to tissues of the inner cornea. Dr Pallikaris described a case where he used the technique in a patient with refractory oedema. The 74-year-old woman presented with photophobia, blurred vision and pain. She had been having recurrent episodes of corneal oedema that was unresponsive to antibiotic therapy and anterior keratectomy.

Corneal abcess

Dr Pallikaris used the Intralase iFS 150-kHz femtosecond laser to create a ring-shaped corneal pocket into the region of the corneal abscess at a depth of 380 μ with an inner diameter of 7.0mm, outer diameter of 7.1mm and an entry port for the injection of 1.4mm in width. Five days after an injection of moxifloxacin into intracorneal the patients showed a clear improvement in her condition, he noted.

He noted that he has also successfully used femtosecond lasers in a series of patients with bullous keratopathy. The technique involves the creation of a keyhole-shaped pocket in the cornea with a Wavelight FS-200 femtosecond laser using its lamellar keratoplasty software, followed by insertion of a biocompatible silicone material. In each of the cases Dr Pallikaris described there was complete re-epithelialisation followed by complete relief of symptoms.