A novel approach to treating presbyopia could also allow patients to change eye colour. The inventor of the new technique, Francis Ferrari MD, France, described the preliminary work in a recent issue of the Journal Français d'Ophtalmologie (J Fr Ophtalmol.,36(6):481-7.)
“You may create a small or a large ring in the cornea. Creating a small ring is a new refractive technique for treating presbyopia. It is like a Kamra, but without a Kamra,” Dr Ferrari, Expert Vision Center, Strasbourg, France, told EuroTimes. You may also create a large ring to change the eye colour (this last procedure will not treat presbyopia).
The presbyopia treatment, dubbed PresbyRing®, (US Patent Application No. 14/051,622), involves creating an intrastromal ring centred on the visual axis with a femtosecond laser. Then a black or coloured pigment is injected into the ring. The internal diameter of the ring is designed to create a pinhole and improve the near and intermediate vision of the nondominant eye while only slightly altering the distance vision of that eye, he explained. The initial in vitro research involved five pig eyes in a post-mortem feasibility study. The eyes were treated with the Intra Corneal Ring program of the Visumax® laser, and then injected with the Biochromaderm dye. Subsequent spectral domain OCT examinations showed complete opacity of the dye. Histological analysis showed a continuous pigmented layer located along the incision, which did not diffuse in the adjacent stroma.
“To our knowledge, this study represents the first experimental attempt to combine two ideas which did not appear to have anything in common: the creation of an intracorneal pinhole to treat presbyopia, and corneal tattooing,” he wrote in the journal article.
The surgery in order to change eye colour, dubbed aesthetic annular keratopigmentation, (US Patent Application No. 14/051,622) involves creating a large intrastromal ring located close to the limbus. Then a coloured pigment is injected into the ring. Dr Ferrari has performed the surgery on one patient, a 49-year-old female. She was treated in both eyes under topical anaesthesia. The procedure took 30 minutes for both eyes. He injected the dye at 150μ depth; with a 9.3mm external diameter and 6.8mm internal diameter.
Preoperative and postoperative visual acuities were 20/20. The patient did not complain of glare or halo following the treatment. Dr Ferrari had conducted a test treatment earlier to confirm that the patient would tolerate the dye. He injected the dye in one eye in ¼ of a ring located in a superior location.
The dye, Biochromaderm®, (Biotic Phocea) is approved in the EU for human corneal use. It is essentially used for cutaneous chromatic repair, eg, tattooing a pathological area of skin or to mask a scar. The dye, which comes in a wide range of colours, has been used in the past to treat iris pathology.
“If I need to reverse the procedure, I could put the original colour on the top of the changed colour. For example, for a patient with brown eyes, I would put a green colour 180μ deep. If she decided she didn’t like the new colour, I could put a brown colour at 150μ deep,” he explained. “In the first patient on whom I’ve performed the surgery, I used a green pigment. The patient is very happy with the result,” he added. Additional safety and efficacy studies are still required, he emphasised.
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