Femtosecond Laser - assisted intrastromal corneal segment implantation - our experience.

  Introduction: The intrastromal corneal ring segments implantation is widely used as an effective method for keratoconus correction. Femtosecond laser technology represents very precise and modern approach in corneal tunnel creation. Nevertheless complication like an extrusion of the implanted ring segment rarely appears. There are few different types of intrastromal corneal segments available. Keraring (Mediphacos Ltd.) is primary designed for keratoconus treatment. MATERIALS AND METHODS: We evaluated results of the Keraring implantations in 32 patients (48 eyes) with keratoconus or with marginal pellucid degeneration. We implanted 78 segments totally in the period from January 2015 to February 2017, with the assistance of femtosecond laser. We present our data collected after the 6 months follow up. Uncorrected visual acuity - UCVA and best corrected visual acuity - BCVA were evaluated. We scored the changes in the subjective and objective refraction. The complications were observed. RESULTS: Preoperative UCVA was in 44 (91,60%) eyes under or equal 0,3. Postoperative UCVA after 6 months was in 29 (60,41%) eyes over or equal 0,3. Visual acuity improved in 38 (79,16%) eyes totally with the gain of 1 to 9 lines, BCVA improved in 27 (56,25%) eyes and in 15 (31,25%) eyes stayed postoperatively unchanged. There was reduction of the spherical equivalent (SE), in the subjective and objective refraction. In our group there we detected 9 (18,75%) extrusions of the implanted ring segment, which occurred on average 7,3 months (range 2/ 16 months) after the surgery. CONCLUSION: Intrastromal corneal ring segments implantation with the femtosecond laser assistance is an effective approach in the keratoconus treatment. Complications are not often observed. With careful selection of the suitable patient it is possible to avoid them. Key words: keratoconus, intrastromal corneal ring segments, femtosecond laser.

[Extraction of a clear lens-cataract as refractive surgery in severe myopia]. / Extrakcia círej sosovky--kararakty ako refrakcná operácia pri t'azkej krátkozrakosti.

Fukals operation (extraction of a transparent lens in severe myopia) was of a long time considered risky in particular because of possible retinal complications. Based on ten years experience (1985 - 1994) the authors provide evidence that modern microsurgical methods, in particular phacoemulsification make it possible to perform this operation at a qualitatively higher level, much more safety and with a lower rate of complications. In a group of 284 operated eyes with myopia (15.96 diopters) were 4.57% transparent lenses, 37.68% with mild partial turbidity and 57.75% with dense or complete turbidity. Corrected vision 5/5 - 5/10 was achieved in 44.37%. Peroperative prolapse of the vitreous body occurred in 5.28%. The most frequent late complication was secondary cataract (26.76%). During the mean follow-up period of 37.57 months there was no case of cystoid oedema of the macula or detachment of the retina. Extraction of a transparent lens or incipient cataract in severe myopia is becoming an alternative method of other refractive operations.

[Nasal reactivity in anesthetized guinea pigs]. / Sledovanie nazálnej reaktivity u anestézovaných morciat.

The authors elaborated a methodical procedure for observing the nasal reactivity in anaesthetized guinea pigs (Pentobarbital Spofa, 32 mg.kg-1 i.p.): Volume changes of the nasal mucosa were estimated from the changes in nasal airflow resistance (Rn). Via tracheostomic aperture the authors introduced a cannula into the nasopharynx. By the use of the cannula they drove doses of continual airflow through the nasal cavities, the airflow doses being 0.5, 1.0, 1.5, thereafter in reversed order: 1.0 and 0.5 l.min-1. Contemporaneously they registered the nasopharyngeal pressure. Rn represented the quotient of the transnasal pressure (the difference between the nasopharyngeal and atmospheric pressure) and the relevant airflow. They filled the nasal cavities for three minutes with histamine solution, the concentration of which was doubled following each application, gradually from 0.625 to 2.0 g.l-1. They discovered that the average values of Rn increase in dependence of histamine doses. Maximal response of the nasal mucosa was detected in between the doses of 0.5-1.0 g.l-1. For estimation of the threshold dose it is necessary to observe still lower histamine concentrations. (Fig. 1, Ref. 14.).