scholarly journals Photorefractive keratectomy results in myopic patients with thin cornea eyes

2015 ◽  
Vol 8 (1) ◽  
pp. 24 ◽  
Author(s):  
Hassan Hashemi ◽  
Mohammad Miraftab ◽  
Soheila Asgari
2018 ◽  
Vol 15 (2S) ◽  
pp. 166-173
Author(s):  
M. S. Stroyko ◽  
S. V. Kostenev ◽  
A. L. Pakhomova

Purpose:to carry out an advanced combined technology, including femtosecond astigmatic keratotomy and topographically-oriented photorefractive keratectomy in order to correct corneal astmigmatism in patients with a thin cornea. Presentation and evaluation of the results of this observation.Patients and methods. There are data of 19 patients (30 eyes) with complex myopic astigmatism combined with a thin cornea who received the operation of femtosecond astigmatic keratotomy (the first stage of an improved combined technology). Mean values before surgery: sph –4.1 ± 2.1 (from –0.3 to –7.8) D, cyl –4.9 ± 1.4 (–3.0 to –7.3) D, UDVA 0.1 ± 0.05 (from 0.01 to 0.2) of the rows of table, CDVA 0.6 ± 0.1 (from 0.4 to 0.9) of the rows of table, Kmax 46.70 ± 1.1 (from 44.50 to 48.50), Kmin 42.8 ± 1.3 (from 40.00 to 44.00), the thickness of the cornea is 470.0 ± 12.7 (from 4470 to 495.0) μm. The second stage: topographically oriented photorefractive keratectomy was performed to the same patients with the aim of correcting residual ametropy. Mean values before surgery: sph –5.3 ± 2.0 (from –1.8 to –8.8) D, cyl –1.6 ± 0.8 (from –0.5 to –3.0) D, UDVA 0.3 ± 0.1 (from 0.1 to 0.6) rows of the table, CDVA 0.7 ± 0.1 (from 0.5 to 0.9) rows of the table, Kmax 46.70 ± 1.1 (from 44.50 to 48.50), Kmin 42.8 ± 1.3 (from 40.00 to 44.00), the thickness of the cornea 464.3 ± 8.3 (from 460.0 to 485.0). All patients from the study received a diagnostic examination by standard and special methods based on the S. Fyodorov Eye Microsurgery State Institution, a screening of the keratoconus on the scanning topograph Pentacam HR “Oculus Optikgerate GmbH”, Germany was carried out. The first stage of the advanced combined technology was used the LenSx Laser (“Alcon”, USA), the second stage — WaveLight EX-500 (“Alcon”, USA), was used.Results. After the completion of two stages of improved combined technology the following results were obtained: reduction of the sph with –4.1 ± 2.1 (from –7.8 to –0.3) to –0.4 ± 0.3 (from –1.0 to 0.0), cyl with –4.9 ± 1.4 (from –7.3 to –3.0) to –0.1 ± 0.1 (from –0.5 to 0.0), Kmax from 44.70 ± 1.1 (from 44.50 to 48.50) to 37.8 ± 1.6 (from 36.00 to 43.00), Kmin 42.80 ± 1.3 (from 40.00 to 44.00) to 37.00 ± 1.3 (from 36.00 to 40.00), CDVA growth with 0.6 ± 0.l (from 0.4 to 0.9) to 0.8 ± 0.1 (from 0.5 to 1.0), UDVA from 0.1 ± 0.05 (from 0.01 to 0.2) to 0.7 ± 0.1 (from 0.4 to 0.9).Conclusion. The improved combining technology, including femtosecond astigmatic keratotomy and topographically — oriented photorefractive keratectomy is effective and safety technology, allowing to correct of corneal astigmatism in patients with a thin cornea. 


Author(s):  
O.V. Pisarevskaya ◽  
◽  
T.N. Iureva ◽  
A.G. Shchuko ◽  
E.P. Ivleva ◽  
...  

2021 ◽  
pp. 112067212110334
Author(s):  
Olga Reitblat ◽  
Assaf Gershoni ◽  
Michael Mimouni ◽  
Eitan Livny ◽  
Yoav Nahum ◽  
...  

Purpose: To examine the clinical outcomes, efficacy, safety, and predictability of transepithelial photorefractive keratectomy (Trans-PRK) operations performed on the day of the first screening visit in comparison with operations scheduled at a following appointment. Methods: Data of consecutive patients with myopia of various degrees, who underwent Trans-PRK, were retrospectively analyzed. Findings were compared between patients who underwent Trans-PRK on the same day of first consultation to patients that underwent surgery at subsequent visits, following initial consultation on a different day. Results: The study included 599 eyes treated on the initial visit day and 1936 eyes treated on a subsequent visit. Mean final spherical equivalent was close to emmetropia in both groups ( p = 0.183). Efficacy indices were 0.928 ± 0.192 in the initial-visit group and 0.945 ± 0.163 in the second-visit group ( p = 0.152). Safety indices were 0.954 ± 0.156 and 0.955 ± 0.151 ( p = 0.707), respectively. No differences between the groups were seen in uncorrected visual acuity (UDVA) of ⩾20/20, ⩾20/25, and ⩾20/32. Only the sub-analysis of patients reaching UDVA of 20/40 or better was slightly lower in the first-visit (95.5%) compared with the second-visit group (97.9%, p = 0.001). Results of attempted correction within ±0.50 D were: 63.3% and 69.0%, respectively ( p = 0.009). Complications profiles in the two groups were comparable. Conclusions: Trans-PRK completed on the day of the first screening appointment demonstrated a similar safety outcome compared with subsequent-visits procedures, and slightly lower, yet comparable, results regarding efficacy and predictability.


2012 ◽  
Vol 69 (10) ◽  
pp. 852-857
Author(s):  
Mirko Resan ◽  
Miroslav Vukosavljevic ◽  
Milorad Milivojevic

Background/Aim. Photorefractive keratectomy (PRK), after laser in situ keratomileusis (LASIK), is commonly performed refractive surgical method worldwide. The aim of this study was to examine the effectiveness and safety of PRK in correction of various strengths of myopia and to assess how much corneal tissue is being removed with one diopter sphere (Dsph) correction by using different optical zones (OZ). Methods. A prospective study with a follow-up period of 6 months included 55 patients of which 100 myopic eyes were treated by PRK method (one eye was included in 10 patients). Myopic eyes with a preoperative best corrected visual acuity (BCVA) = 1.0 (20/20) were analysed. In order to assess the effectiveness of PRK operated myopic eyes were divided into four groups according to the dioptric power: 1)? -1.75 Dsph (n = 26); 2) from -2 to -3.75 Dsph (n = 44); 3) from -4 to -6.75 Dsph (n = 23), and 4) ? -7 Dsph (n = 7). Myopic eyes with preoperative BCVA ? 0.9 (amblyopic eyes) were excluded from the study, as well as eyes with astigmatism > -1.5 Dcyl. To assess the effectiveness of PRK we examined the percentage of eyes in the mentioned groups, which derived uncorrected visual acuity (UCVA) 6 months after the intervention to the following: a) UCVA = 1.0 (20/20) and b) UCVA ? 0.5 (20/40). To assess the safety of PRK we examined the frequency of intraoperative and postoperative complications. To estimate how much corneal tissue was removed with one Dsph correction by using different OZ, we used preoperative and postoperative (after 6 months) central pachymetry values expressed in ?m and volume of cornea (central 7 mm) expressed in mm?. In that sense, we used only the myopic eyes with clear preoperative spherical refraction. The total number of these eyes was 27, of which 16 eyes were treated using a 6.5 mm OZ and 11 eyes using a 7 mm OZ. Results. Refractive spherical equivalent (RSE) for all eyes was in the range from -0.75 to -8.75 Dsph, and preoperative mean value of RSE with standard deviation (mean RSE ? SD) was -3.32 ? 1.83 Dsph. Six months after PRK, 91% of eyes had UCVA = 20/20, and 99% of eyes had UCVA ? 20/40. In the first group (? -1.75 Dsph) preoperative mean RSE ? SD was -1.34 ? 0.32 Dsph, six months after PRK, 96% of eyes had UCVA = 20/20, and 100% of eyes had UCVA ? 20/40. In the second group (from -2 to -3.75 Dsph) preoperative mean RSE ? SD was - 2.95 ? 0.57 Dsph, six months after PRK, 89% of eyes had UCVA = 20/20, and 100% of eyes had UCVA ? 20/40. In the third group (from -4 to -6.75 Dsph) preoperative mean RSE ? SD was - 4.93 ? 0.70 Dsph, six months after PRK, 100% of eyes had UCVA = 20/20. In the fourth group (? - 7 Dsph) preoperative mean RSE ? SD was -7.71 ? 0.67 Dsph, six months after PRK, 57% of eyes had UCVA = 20/20, and 86% of eyes had UCVA ? 20/40. There were no intraoperative complications while postoperative complications occurred in 2 patients - in both cases in one eye (2%). In that cases, epithelial defects were detected. In the group of eyes that were treated by 6.5 mm OZ mean RSE ? SD was -2.45 ? 0.99 Dsph, the ablation depth per 1 Dsph was 17.54 ? 5.58 ?m and ablated volume of central 7 mm cornea by 1 Dsph was 0.43 ? 0.18 mm?. In the group of eyes that were treated by 7 mm OZ mean RSE ? SD was -3.32 ? 2.26 Dsph, the ablation depth per 1 Dsph was 23.73 ? 6.91 ?m and ablated volume of central 7 mm cornea by 1 Dsph was 0.61 ? 0.31 mm?. Conclusion. PRK is effective and safe refractive surgical method for correcting myopia up to -8 .75 Dsph. OZ size is the main factor determining the depth of the excimer laser ablation of the corneal tissue volume consumed by 1 Dsph. Higher OZ value determines higher consumption of cornea tissue.


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