Hydrogel keratophakia: a microkeratome dissection in the monkey model.

Area of Science:

• Ophthalmology
• Biomaterials Science
• Corneal Surgery

Background:

• Intracorneal implants offer a method for refractive correction.
• Hydrogel materials are being explored for their biocompatibility and optical properties in ophthalmic applications.

Purpose of the Study:

• To evaluate the safety and efficacy of high water content Vistamarc hydrogel intracorneal implants in a primate model.
• To assess the refractive and keratometric outcomes following intracorneal lens implantation.

Main Methods:

• Vistamarc hydrogel implants with varying water content (58-72%) and powers (+7.25 to +17.00 D) were fabricated.
• The Barraquer microkeratome technique was used for implantation in 14 rhesus monkey eyes, with contralateral eyes serving as controls.
• Animals were followed for approximately 51 weeks, with refractive and keratometric measurements taken post-implantation.

Main Results:

• A refractive yield of 118% +/- 34% and a keratometric yield of 92% +/- 30% were observed.
• A strong linear correlation (r=0.74) was found between measured and expected refractive changes.
• Refraction stabilized within 2-3 diopters after 20 weeks; hydrogels were well-tolerated with minimal interface issues, though implant edge design influenced light scattering.

Conclusions:

• High water content Vistamarc hydrogel intracorneal implants are well-tolerated in corneal tissue and achieve predictable refractive correction in a primate model.
• The study suggests that implant edge design may impact optical quality, with wedge-shaped edges potentially reducing light scattering.
• Further investigation into optimal implant edge geometry is warranted for enhanced visual outcomes.