Intrastromal Tunnel Research Articles

Comparative Analysis of the Intrastromal MyoRing Implantation performed with the Femtosecond Laser

ABSTRACT Purpose To comparatively analyze the intrastromal MyoRing implantation with femtosecond laser (FL) using the standard and optimized technologies in the experiment and based on the long-term clinical-functional results of the patients with keratoconus (KC) at stages II and III. Materials and methods The experimental work was performed on 24 eyes of rabbits. All eyes were divided into six groups according to the method of operation. In the clinical part of the research, the surgical treatment of 70 patients (76 eyes) with KC at stages II and III was done. Depending on the technology of the operation, all patients were divided into two groups. Group I consisted of 29 patients (32 eyes) with KC, in which MyoRing implantation was performed according to the standard, group II consisted of 31 patients (32 eyes) with KC, in which MyoRing implantation was performed according to the optimized technology. Results Higher voltage was required for stretching samples of the second group in comparison with the third and the sixth group in comparison with the fifth group. In group I, during the period of 6 to 36 months the surgery reverses keratometry, corneal thickness above the MyoRing, and posterior corneal elevation. In group II, 12 months after surgery the clinical and functional parameters remained stable throughout the period of observation. Conclusion Greater reduction in corneal biomechanical stability was observed after formation of the intrastromal pocket in comparison with an intrastromal tunnel; a more pronounced increase in the strength characteristics of the cornea was observed after implantation of the ring in intrastromal pocket, compared with implantation intracorneal segments in intrastromal tunnel, and with increasing depth of intrastromal ring implantation. Application of optimized MyoRing implantation technology compared with standard allows more biomechanical parameters of the cornea to improve and reduce the risk of the ring protrusion. How to cite this article Sinitsyn MV, Pozdeyeva NA, Pashtayev NP. Comparative Analysis of the Intrastromal MyoRing Implantation performed with the Femtosecond Laser. Int J Kerat Ect Cor Dis 2017;6(2):49-57.

Femtosecond-Assisted Big Bubble: A Feasibility Study.

To evaluate the feasibility of femtosecond laser-assisted (FA) tunnel creation as a pretreatment for creating a big bubble (BB) to pneumo-dissect the corneal stroma from Descemet membrane. Five human cadaver eyes received pretreatment using a femtosecond laser. An intrastromal tunnel, along with a side cut, was achieved using customized femtosecond corneal disruption (custom mask). Before treatment, optical coherence tomography was performed and the intrastromal tunnel was intended to achieve a parallel orientation with respect to the corneal endothelial cell layer (50 µm above the endothelium). Surgical dissection of the side cut using a Sinskey hook was performed, followed by insertion of a deep anterior lamellar keratoplasty cannula into the tunnel and pneumo-dissection (BB). All corneas after treatment were prepared for histologic evaluation (light microscopy). FA pretreatment was successful in all 5 cadaveric corneas, and the BB was achieved in all eyes as well. Histologic evaluation of the corneas revealed complete separation of Descemet membrane and stroma in all eyes, with no remaining stroma attached to Descemet membrane and no signs of perforation. FABB seems feasible because pneumo-dissection of the corneal stroma from Descemet membrane was achieved in all human cadaver corneas of this experimental study. Optical coherence tomography, corneal histology, and macroscopic evaluation revealed complete Descemet-stromal separation.

Novel lamellar, flap-based tattooing techniques for corneal opacities in scarred and vascularized blind eyes.

The aim of this study was to describe novel, flap-based tattooing techniques for the treatment of disfiguring corneal scars in blind eyes. Several new modifications of intrastromal corneal tattooing techniques were performed in 6 patients. In corneas with a low risk of perforation, a large limbus-to-limbus lamellar flap was prepared, and the tattooing dyes were spread over the entire stromal bed. After additional puncturing of the dyes into the stroma, the flap was closed and sutured ("large flap technique"). In fragile corneas where convenient preparation of a large flap was not possible, a central small flap was prepared, and the "pupil" was tattooed in analogy ("small flap technique"). Afterward, the corneal periphery corresponding to the "iris" was tattooed, either by puncturing or injecting the dye into peripheral intrastromal tunnels ("tunnel technique"). Two eyes were tattooed using a large flap, and 4 eyes were tattooed using a small flap. Here, the corneal periphery of 3 eyes was tattooed by puncturing, whereas 1 eye was tattooed using the tunnel technique. All tattooing procedures were performed without complications and with good cosmetic results. These novel, flap-based tattooing techniques are alternatives to previously reported procedures and can be adapted to the individual corneal constitution. Further, the tunnel technique is an easy-to-perform method that provides good tattooing results.

Intraoperative Use of AS-OCT During Intrastromal Corneal Ring Segment Implantation

To evaluate femtosecond laser-created tunnels intraoperatively by anterior segment optical coherence tomography (AS-OCT) during intrastromal corneal ring segment implantation. The study prospectively examined 13 eyes of 11 patients who underwent intrastromal corneal ring segment surgery with the aid of femtosecond laser. All eyes had keratoconus as the primary diagnosis. Eyes were examined by AS-OCT to image the tunnel immediately after femtosecond laser and before ring segment implantation. Tunnel depth was calculated automatically using the software's flap tool and calipers. The presence of air bubbles demonstrated the tunnel successfully by AS-OCT. Tunnel depth was measured at eight locations in four cross-sections of high-resolution cornea images. An overall evaluation was also made by changing the scan direction 360°. After confirmation that a uniform tunnel was satisfactorily created at the aimed depth, surgery proceeded with segment implantation. AS-OCT can be used intraoperatively to assess femtosecond laser-created tunnel in intrastromal corneal ring segment implantation. The qualitative and quantitative evaluation of the intrastromal tunnel by AS-OCT before implantation of the ring segments is a practical intraoperative approach that may offer a safer surgery.

Femtosecond-Assisted Keratopigmentation Double Tunnel Technique in the Management of a Case of Urrets-Zavalia Syndrome

To describe the successful use of a double intrastromal tunnel femtosecond-assisted keratopigmentation technique to manage a case of unilateral Urrets-Zavalia syndrome. A 33-year-old man was referred with a history of trauma in his right eye due to a labor-related accident. Because of myopic anisometropia, he had been previously implanted with an angle-supported phakic intraocular lens. The patient presented iris atrophy and a fixed dilated pupil. He complained of severe and incapacitating photophobia, glare, and decreased vision. To obtain a complete iris replica, the surgery involved creation of double keratopigmented intrastromal tunnels using femtosecond laser and micronized mineral pigments. The deepest layer was stained black first and then the superficial layer was stained with a contoured greenish blue-gray color, which matched the contralateral eye. In the immediate postoperative period, the patient reported a complete elimination of photophobia associated with the corrected distance visual acuity improvement. A very adequate cosmetic outcome was also achieved. Stability was observed during the 12-month follow-up. A femtosecond-assisted keratopigmentation technique using 2 pigmented intrastromal tunnels to achieve an intracorneal pigmented replica of the iris was effective in improving the patient's severe visual function disability and cosmetic appearance. To the best of our knowledge, this is the first report of severe visual function disability caused by atrophic iris and a fixed dilated pupil treated with double intrastromal layers of keratopigmentation by means of femtosecond-created tunnels.

Intracuring: Intrastromal Corneal Application of Dental Flowable Composite

To evaluate an intracuring method by changing the corneal curvature. An intrastromal tunnel was created by femtosecond laser in five cadaveric sheep eyes. Dental flowable restorative composite was used to fill the tunnel. A light-emitting diode light was applied for polymerization for 20 seconds. Flat plastic material was used for pressure on the cornea during polymerization. Keratometric measurements were obtained in all eyes using a rotating Scheimpflug camera. Remarkable changes on the corneal curvature were observed after the intracuring method. Inferior or inferonasal flattening and opposite steepening was observed in all sheep eyes. The average flattening effect of this method was 10.6 diopters. This new application may be a promising technique for the treatment of keratoconus. The application of this technique in humans could offer improved treatment options in the future.

Intracorneal lenses for the treatment of presbyopia: visual outcomes and safety

Abstract Purpose To investigate the visual outcomes and safety of Intracorneal lenses (Invue Lens, Biovision AG, Switzerland) for the treatment of presbyopia. Methods This was a prospective clinical study. An intrastromal corneal tunnel was created using a microkeratome composed by a control unit, a suction ring and a cartridge. The lens was inserted within the cornea tunnel of the non‐dominant eye of 45 presbiopian patients. Mean age was 52,33 years old ± 3,29 (25 males and 20 females). The follow‐up was up to 12 months. Results In the operated eye, mean uncorrected visual acuity for distance (UVA‐D) preoperatively, one day, one week one month, three months,six months and 1 year after surgery was 20/20, 20/40, 20/40, 20/32, 20/32, 20/32 and 20/32 respectively, whereas for near (UVA‐N) was 20/50, 20/40, 20/30, 20/30, 20/25, 20/25 and 20/30.Binocular far vision was not altered.Contrast sensitivity tests demonstrated a decrease in scotopic and mesopic conditions.Wavefront analysis demonstrated an increase in all high order aberrations, whereas maximum myopic effect was demonstrated in 3,5 mm zone,which corresponded in the diameter of the lens. No tissue alterations of the cornea were found using corneal confocal microscopy. No intra or post‐operative complications were demonstrated up to one year after surgery. Conclusion Intracorneal lenses for presbyopia seems to be a safe and effective method to correct presbyopia in patients aged between 45 to 55 years old; a target group which is considered too old for refractive laser surgery and too young for clear lens extraction. Longer follow‐up and a larger population are necessary in order to draw more significant results of this new surgical approach for the treatment of presbyopia.