Biomedical subjects

V Lorencová

Publications and source records attributed to V Lorencová.

5 recordsLinked to original sources

PubMed2003

[Corneal surface analysis].

Fourier analysis is a powerful method of evaluating the surface of the cornea. In 50 patients after photorefractive keratectomy included in our study we measured spherical equivalent, regular astigmatism, irregular astigmatism and decentration retrospectively acquired by Fourier series analysis of corneal topography data 1, 3, 6 and 12 months after operation. Postoperative decentration increased significantly from a mean preoperative value. The preoperative and postoperative values are not significantly different. The Fourier spherical equivalent and the values of keratometric spherical (equivalent) are highly correlated. Correlation among decentration, irregular astigmatism and best corrected visual acuity is important for clinical practice. Due to Fourier analysis we obtain information, which could explain worse results of some surgeries.

Astigmatism↗

PubMed2003

[Refractive surgery in myopia up to -6D].

OBJECTIVE: To evaluate the clinical results in patients with myopia up to -6 dioptres (D) after refraction surgery, evaluate their stability and compare photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). MATERIAL AND METHODS: The authors evaluated before and after surgery the refraction values in patients with myopia up to -6 D operated in 1999 and 2000. The patients were subjected to standard examination before operation, one week, 1, 3, 6 and 12 months after operation. The group comprised a total of 542 eyes, 452 PRK eyes and 90 LASIK eyes. RESULTS: After PRK surgery the mean spherical refraction after one year was -0.35 +/- 0.71 D, the mean astigmatism -0.63 +/- 0.38 D, UCVA 0.90 +/- 0.19, BCVA 0.98 +/- 0.11. After LASIK surgery after one year the mean spherical refraction was -0.10 +/- 0.81. D, the mean astigmatism -1.05 +/- 0.65 D, UCVA 0.80 +/- 0.24, BCVA 0.86 +/- 0.21. CONCLUSION: Both methods proved effective and safe for correction of myopia up to -6 D. The results at our clinic are comparable with other departments and are stable in different years. PRK and LASIK achieve equal postoperative results after an interval of 3 to 6 months following surgery.

Astigmatism↗

PubMed2003

[Long-term results of photorefractive keratectomy in myopia up to -6 D].

OBJECTIVE: To present clinical results of patients with myopia up to -6 dioptres (D) after photorefractive keratectomy (PRK) and evaluate their stability during a 4-year period. MATERIAL AND METHODS: The authors evaluated retrospectively the refraction before and after surgery in patients with myopia up to -6 D during the period from September 1997 till December 2000. The group comprised a total of 847 eyes. The mean spherical refraction during the whole follow up period was before surgery -3.61 +/- 1.17 D, the mean astigmatism was -0.65 +/- 0.63 D, non-corrected visual acuity (UCVA) 0.09 +/- 0.09, the visual acuity with optimal correction (BCVA) 1.21 +/- 0.30. RESULTS: One year after PRK we achieved in our group a mean spherical refraction of -0.17 +/- 0.74 D, a mean astigmatism of -0.61 +/- 0.43 D, UCVA 0.92 +/- 0.25, BCVA 1.02 +/- 0.19. CONCLUSION: Photorefractive keratectomy is an effective and safe method for correction of myopia up to -6 D. The results as regards refraction were comparable with other departments and did not differ much during individual years. Stabilization occurs 3-6 months after the operation.

Follow-Up Studies↗

PubMed2003

[Stability of corneal optic power after photorefractive keratectomy].

Changes in the values of optical power of cornea in patients after photorefractive keratectomy (PRK) obtained by Fourier analysis of videotopographic picture of cornea were investigated. The authors compared changes of cornea surface (optical power) in patients with preoperation myopia up to 6 and more than 6 diopters. Moreover, the changes of absolute values of corneal optical power were compared with the development of refraction of the optical system as a whole. In patients with a lower degree of myopia the cornea optical power became stable up to 6 months after the operation. The cornea surface in patients with higher myopia was still changing one year after the operation. The changes of optical power of cornea in patients with a higher myopia were more marked, but the differences were not statistically significant (except for the period after cornea ablation). There was not any significant difference between the changes of objective refraction and the changes of cornea optical power. The main cause of fluctuating postoperative refraction is apparently the change of cornea surface associated with healing of cornea.

Adult↗

PubMed2001

[PRK and LASIK in patients with myopia ranging from -6 to -9 D] ].

OBJECTIVE: Observing of effectiveness, safety and short-term stability of patients with myopia ranging from -6.0 to -9.0 diopters (D) after surgery and their comparison. PARTICIPANTS AND METHOD: We were retrospectively analyzing pre- and postoperative outcomes of patients with myopia ranging from -6.0 to -9.0 D. 90 eyes were examined before laser in situ keratomileusis (LASIK) with mean spherical equivalent refraction -7.64 +/- 0.84 D and mean cylinder -1.23 +/- 1.1 D. 56 eyes were examined before photorefractive keratectomy (PRK) with mean spherical equivalent refraction -6.92 +/- 0.72 D and mean cylinder -0.60 +/- 0.55 D. Patients were examined before operation, one week, one month, three months, six months, nine months and one year after operation. Data were collected and analyzed by the computer programme. RESULTS: We observed the patients who underwent the operation and six months after surgery we received following results: After PRK mean spherical equivalent refraction was -0.23 +/- 1.24 D, mean cylinder -0.83 +/- 0.42 D, uncorrected visual acuity (UCVA) 0.86 +/- 0.35, best spectacle-corrected visual acuity (BCVA) 1.13 +/- 0.33. After LASIK mean spherical equivalent refraction was -0.29 +/- 1.19 D, mean cylinder -1.14 +/- 0.77 D, UCVA 0.65 +/- 0.25, BCVA 0.83 +/- 0.25. One year after PRK mean spherical equivalent refraction was -0.44 +/- 1.26 D, mean cylinder -0.80 +/- 0.57 D, UCVA 0.81 +/- 0.31, BCVA 0.97 +/- 0.21. After LASIK mean spherical equivalent refraction was -0.14 +/- 0.86 D, mean cylinder -1.26 +/- 0.89 D, UCVA 0.75 +/- 0.25, BCVA 0.89 +/- 0.20. CONCLUSIONS: Both methods are effective and their results after 3 to 6 months after laser treatment in patients with myopia ranging from -6.0 to -9.0 D were comparable. Based on the complex evaluation, we prefer LASIK nowadays.

Adult↗