ELECTRON MICROSCOPY OF THE CORNEAL STROMA AFTER THE STANDARD CROSS-LINKING AND USING FEMTOSECOND LASER IN EXPERIMENT

Purpose. The study and comparison of the corneal tissues condition after the standard corneal collagen cross-linking (CXL) and femto-cross-linking in experiment.Material and methods. The study used 9 male Chinchilla rabbits (18 eyes) weighing 2-3kg, which were divided into 3 groups depending on the type of surgical intervention: femtocross-linking, standard CXL and the control group where the femtolaser formation of pocket were performed without the crosslinking procedure. Rabbits were taken out of the experiment at 1 week, 1 and 3 months. The eyes were enucleated, cornea was excised using a 9.0mm trephine. The corneal discs were examined by the transmission electron microscope JEOL 1200 EX (Japan).Results. Analysis of microscopic pictures from the transmission electron microscopy after the femto-cross-linking and the standard CXL revealed an equal quantity of cross-links in collagen fibers. After the standard CXL the changes in the basal membrane and basal epithelial cells were visualized with signs of polymorphism and increased intercellular spaces.Conclusion. In the electron-microscopic images of ultrastructure in the corneal stroma the comparable changes were found in the standard group and femto-cross-linking that suggests an identical efficiency of both techniques. The detected changes in the basal membrane a week after the standard CXL suggests a traumatism of the stage of epithelium removal in contrast to an atraumatic formation of stromal pocket using the femtosecond laser

Tactical approaches to surgical management of lens subluxation

A proper treatment of crystalline lens subluxation presents one of the greatest challenges in ophthalmic surgery. To deliver the best possible outcomes a surgeon is required to assess adequately preoperative data findings to devise a general surgical plan. Taking into account the large variability of the clinical picture observed in this category of patients, it is also necessary to provide several alternative tactics.A basis of contemporary approaches to ectopic lens extraction strongly focuses on minimally invasive phacoemulsification techniques. The essence of innovative thinking in this field could be described as capsular bag preservation for endocapsular placement of intraocular lenses (IOLs). With this ultimate goal in mind, various technical tricks and a multitude of devices ranging from plastic hooks to femtosecond lasers were introduced. A thorough understanding of the modern armamentarium of surgical techniques and implants would be beneficial to a surgeon to be maximally prepared to numerous problems and challenges specific to lenses with compromised zonular support. Bringing non-standard situations of lens subluxation to the regular in-the-bag IOL placement, even though highly preferable, could not be assured in every case.The second part of the review article provides information on alternative strategies for the IOL fixation – from historical and little relevant today methods to the latest i nnovations in the field

COMPARATIVE ANALYSIS OF CLINICAL AND FUNCTIONAL RESULTS OF THE INTRASTROMAL SEGMENTS AND MYORING IMPLANTATIONS IN KERATOCONUS USING THE FEMTOSECOND TECHNOLOGY

Purpose. A comparative analysis of clinical and functional results of the intrastromal segments and MyoRing implantations in keratoconusof the stages II and III using the femtosecond technology.Material and methods. There were examined and operated 117 eyes (98 patients) with keratoconus of the stages II and III (classification by Amsler M., 1961). In the group I, 30 eyes (23 patients) underwent implantation of intrastromal MyoRing (Dioptex,Austria) using the femtosecond technology. The group II included 87 eyes (75 patients) with implantations of intrastromal corneal segments (the Eye Microsurgery Research Experimental Production Ltd.) using the femtosecond technology. The average follow-up was 10 months.Results. Patients were examined 3 and 10 months after the surgery. After the femtosecond laser MyoRing implantation in the subgroups 1 and 2 the UCVA and BCVA increased by 3-4 lines, mean keratometry readings in the subgroup 1 decreased by 9.49D, in the subgroup 2 – by 13.6D. After femtosecond laser implantation of intrastromal corneal segments (ICS) in the subgroups 1 and 2 the UCVA and BCVA increased by 2-3 lines, mean keratometry readings in the subgroup 1 decreased by 3.96D, in the subgroup 2 – by 6.1D.Conclusion. 1 The UCVA growth was by 15%, the BCVA – by 11% after the MyoRing implantation compared with the ICS implantation in keratoconus of the stage II and the UCVA – 1.8 times in patients with keratoconus of the stage III. The BCVA values in keratoconus of the stage III after the MyoRing implantation and the ICS implantation were comparable. 2. The femtosecond laser MyoRing implantation led to a more pronounced decrease of the mean keratometry readings 2.4 times in patients with keratoconus of the stage II and 2.2 times in keratoconus of the stage III versus implantation of intrastromal corneal segments

TERMS AND IMPACT ON A REFRACTIVE EFFECT OF A CORRECTION OF THE MYORING POSITION IN PATIENTS WITH KERATOCONUS

Purpose. To determine the time periods and impact on the refractive effect of a correction of the MyoRing position in patients with keratoconus. Material and methods. The MyoRing implantation was performed at the clinic according to an optimized technology in 150 patients (160 eyes) with keratoconus of the stages II and III. In the postoperative follow-up in 6 eyes of them (3,75%) (6 patients) the correction of the ring position inside the intrastromal pocket was carried out to achieve a higher refractive result. The correction of MyoRing position was performed in 2 eyes 1 month later, in 1 eye – 3 months later, another 1 eye – after 6 months and in the remaining two eyes – 9 and 10 months after surgery. The follow-up was 36 months.Results. In the postoperative period a correction of hyperopic refraction, an improved visual acuity, an increased sphericity of the cornea were noted in all patients. In case of the correction of ring position by 0.5mm with an inner 5.0mm diameter and in a 320mm height in the direction opposite ectasia, the hyper-effect was offset to 5.0D, at a 300-micron height to 4.5D, at a 280µm height – 4.0D of spherical refraction.The difference in the confocal microscopy were revealed in 2 eyes after the correction of MyoRing position 9 and 10 months after the implantation. Areas of transparency violations with signs of fibroplasia were visualized in the posterior stroma, located in the intra-stromal pocket in the projection of the previous ring location during the entire period of observation.Conclusions. 1. The optimal time periods for the correction of the ring position are the first 6 months after the performed surgery. 2. There were detected a dependence of the compensated value of refractive spherical component on the ring parameters and directions of its shifting relative to the visual axis of the eye

The two-year analysis of clinical and functional results of MyoRing implantation in patients with keratoconus

Purpose. A comparative analysis of clinical and functional parameters of the corneal surface in patients with keratoconus (KC) of the stages II, III after MyoRing implantation into the intrastromal pocket formed using the femtosecond laser according to the Pentacam device.Material and methods. The surgery was performed in 70 eyes (65 patients) with KC of stages II and III. Depending on the KC stage the patients were divided into 2 groups. The group I consisted of patients with the KC stage II – 41 eyes (38 patients), the group II – patients with the KC stage III – 29 eyes (27 patients). The MyoRings were implanted into the intrastromal pocket formed using the femtosecond laser in all patients. Visometry, biomicroscopy with a comprehensive examination of the corneal surface using the Pentacam device were carried out pre- and postoperatively. The follow-up period was 24 months.Results. In the group I, the mean value of uncorrected visual acuity (UCVA) 12 months after surgery increased 3.3 times, best corrected visual acuity (BCVA) – 2.3 times. In the group II the UCVA 12 months after surgery increased 10 times, the BCVA – 2.1 times. In both groups, the UCVA and BCVA remained stable throughout the entire follow-up period. In both groups 12 months after surgery an improvement in values of all corneal topography indices, a significant reduction in elevation of the anterior and the posterior corneal surface, a reduction of the distance from the vertex of cornea to its thinnest point, which remained stable throughout the 24 months of the follow-up were noted according to the Pentacam device.Conclusion. According to the Pentacam the MyoRing implantation into the intrastromal pocket formed using the femtosecond laser in the follow-up of 24 months showed a significant improvement in both groups of all corneal topography indices, a flattening of the anterior and posterior corneal surfaces, a centering of corneal vertex, that was confirmed by a decrease in the elevation of anterior and posterior corneal surfaces and a centering of its thinnest point and was accompanied by an improvement of refractive indices

DEEP ANTERIOR LAMELLAR REKERATOPLASTY AFTER ANTERIOR LAMELLAR REKERATOPLASTY USING FEMTOSECOND LASER. A CASE REPORT

We report a clinical case of femtosecond laser (FS) assisted deep anterior lamellar keratoplasty (DALK) performed with the IntraLase FS 60 kHz laser after a previous FS anterior lamellar keratoplasty (ALK). Patient, 28-year-old female with clear lamellar corneal graft 2 years after the initial surgery having the low BCVA (0.2) due to a corneal interface scarring and posterior residual corneal layers irregularities underwent the FS DALK. The surgery was successful, corneal graft was clear. Endothelial cell loss was minimal (2809 mm2 pre-op. and 2716 mm2 post-op). The BCVA improved to 0.5 one week after the surgery. At a 1-month examination the corneal graft remained clear, ECD=2695 mm2, BCVA=0.6

COMPARATIVE ANALYSIS OF LONG-TERM CLINICAL AND FUNCTIONAL RESULTS OF THE INTRA-STROMAL MyoRing IMPLANTATIONS ACCORDING TO OPTIMIZED AND STANDARD TECHNOLOGIES USING A FEMTOSECOND LASER IN KERATOCONUS PATIENTS

Purpose. Comparative analysis of long-term clinical and functional results of the intra-stromal MyoRing implantation according to standard techniques and optimized technologies using a femtosecond laser (FSL) in patients with keratoconus (KC), stages II and III.Material and methods. Results of surgical treatment of 60 patients (64 eyes) were analyzed in patients with KC of stages II and III. Depending on the technique of the operation, all patients were divided into  two groups. The group I consisted of patients with KC, who underwent the MyoRing implantation according to the standard technique, the group II used an optimized technology. The group I included  29 patients (32 eyes), the group II – 31 patients (32 eyes). In the group I the intra-stromal pocket of 9.0mm diameter was formed at a depth of 300 microns using the FSL. In the group II the intra-stromal pocket of 8.0mm diameter was formed at a depth of 80% of the minimum thickness of the cornea at the place of MyoRing location also using the FSL. The follow-up period averaged 36 months.Results. In the group I, in the period from 6 to 36 months postoperatively a regress was detected  in keratometric data, corneal thickness over the MyoRing and presence of posterior corneal elevation. In the  group II  all postoperative clinical and  functional parameters  achieved 12 months remained stable throughout the follow-up period. Both groups had no intra-operative complications. In group I, one case of the MyoRing protrusion was observed 24 months after surgery.Conclusion.  Application of the  optimized MyoRing  implantation technology compared to the standard one allows to improve more bio-mechanical parameters of the cornea and to reduce the risk of the ring protrusion

STRENGTH CHARACTERISTICS OF THE RABBIT CORNEA AFTER INTRA-STROMAL IMPLANTATION OF VARIOUS IMPLANTS USING A FEMTOSECOND LASER

Purpose.  Comparative  experimental  study  of  the  effect  of  the implantation of various intrastromal implants using a femtosecond laser (FSL)on the strength properties of the rabbit cornea.Material and methods. The experimental work was performed on 24 corneas of isolated eyes of 12 rabbits enucleated 1 month after the slaughter. All eyes were divided into 4 groups, depending on the method of operation. Formation of intra-stromal pockets (IP) and tunnels (IT) was performed using the FSL Femto Visum. The eyes of rabbits with intact corneas were included into the first control group. In the group 2, the intrastromal segment 350° was implanted into the IT. In the group 3,the MyoRing was implanted into the IP. In the group 4, the intrastromal closing ring with a «lock» was implanted into the IT.Results. After the implantation of intrastromal implants in comparison with the control group it was noted that the strength of the examined cornea of rabbits was increased to break. The greatest increase in the strength properties of the rabbit cornea was observed after the implantation of the intrastromal closing ring with a «lock» in comparison with the implantation of the intrastromal segment of 350° and the MyoRing.Conclusions. Implantation of intrastromal rings and segments leads  to  an  increase  in  the  strength  properties  of  the  cornea.Implantation of an intrastromal closing ring with a «lock» leads to the greatest increase in the strength properties of the cornea compared with the implantation of the intrastromal segment of 350° and the MyoRing