Flap Melting Over Corneal Inlay for Hyperopic Correction

Surgical Technique to Treat Presbyopic Inlay-Associated Corneal Haze With Sequential Excimer Photoablation: A Case Series

PURPOSE

To describe an approach using sequential excimer laser ablation of the stromal surface of the corneal flap with or without subsequent excimer ablation to the stromal bed to reduce presbyopic inlay-associated corneal haze.

METHODS

Twelve patients who underwent KAMRA inlay (Acufocus) explantation due to corneal haze were included. The mean interval between explantation and the primary surgery (phototherapeutic keratotomy [PTK] to corneal flap) was 16.2 ± 29.7 months (range = 1 to 83 months). The corneal flap was lifted and laid on an evisceration spoon and an excimer laser was used to ablate the flap stroma by 30 to 40 µm depth. Subsequently, an excimer laser was used to ablate and treat the stromal bed following a second flap lift according to the manifest refraction, leaving a minimal residual stromal bed thickness of greater than 300 µm. For both procedures, mitomycin C 0.02% was applied to the stromal bed before the flap was replaced and a bandage contact lens applied.

RESULTS

Reductions in corneal haze were observed, following PTK to the corneal flap with or without photorefractive keratectomy (PRK) to the stromal bed, both clinically and on imaging. No significant changes in uncorrected distance visual acuity (P = .442) and corrected distance visual acuity (P = .565) were observed. Improvements were observed for both spherical equivalent refractive errors (P = .036) and corneal light backscatter (P = .019). There were significant improvements in spherical aberrations (P = .014) but no changes in total lower and higher order aberrations.

CONCLUSIONS

PTK to the corneal flap with or without subsequent stromal bed PRK is an effective technique in treating corneal haze following presbyopic inlay explantation. [J Refract Surg. 2023;39(9):639-646.].

Biology of keratorefractive surgery- PRK, PTK, LASIK, SMILE, inlays and other refractive procedures

The outcomes of refractive surgical procedures to improve uncorrected vision in patients-including photorefractive keratectomy (PRK), laser in-situ keratomileusis (LASIK), Small Incision Lenticule Extraction (SMILE) and corneal inlay procedures-is in large part determined by the corneal wound healing response after surgery. The wound healing response varies depending on the type of surgery, the level of intended correction of refractive error, the post-operative inflammatory response, generation of opacity producing myofibroblasts and likely poorly understood genetic factors. This article details what is known about these specific wound healing responses that include apoptosis of keratocytes and myofibroblasts, mitosis of corneal fibroblasts and myofibroblast precursors, the development of myofibroblasts from keratocyte-derived corneal fibroblasts and bone marrow-derived fibrocytes, deposition of disordered extracellular matrix by corneal fibroblasts and myofibroblasts, healing of the epithelial injury, and regeneration of the epithelial basement membrane. Problems with epithelial and stromal cellular viability and function that are altered by corneal inlays are also discussed. A better understanding of the wound healing response in refractive surgical procedures is likely to lead to better treatments to improve outcomes, limit complications of keratorefractive surgical procedures, and improve the safety and efficiency of refractive surgical procedures.

Permavision intracorneal inlay after sixteen years. Regression of initial refractive hyperopia

According to the available scientific literature, 77 patients underwent Permavision inlay worldwide, between 2004 and 2007. This study reported about the use of Permavision intracorneal inlay to increase the central corneal curvature and to correct hyperopia. A 32-year-old male patient went to the Tecnolaser Clinic Vision ® facilities for a refractive study. Preoperative refraction without cycloplegia was +6.00 D in the right eye (RE) and +4.00 in the left eye (LE). The surgery was performed for both eyes on December 2, 2003. The Carriazo-Barraquer mechanical microkeratome (Moria) was used to create a 180 μm-thick corneal flap with a diameter of 8.5 mm. After lifting the flap, the corneal inlay was placed centrally above the pupil and the flap was re-positioned. In this case report, the patient reverted to the initial refractive situation. The first refractive regression appeared at twelve-month follow-up. After sixteen years, it was found a decrease in maximum corneal curvature, an increase in mean corneal densitometry percentage, and no important changes in the central corneal thickness. In the reported case, the cornea reverted to its original shape. In the scientific literature, this is the first case report of a non-explanted Permavision inlay after sixteen years.