PMID- 23155605
OWN - NLM
STAT- MEDLINE
DCOM- 20121211
LR  - 20190918
IS  - 0042-8450 (Print)
IS  - 0042-8450 (Linking)
VI  - 69
IP  - 10
DP  - 2012 Oct
TI  - [Photorefractive keratectomy for correction of myopia--our one-year experience].
PG  - 852-7
AB  - 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 
      PRIK 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) < or = -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) > or = -7 
      Dsph (n=7). Myopic eyes with preoperative BCVA < or = 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 > or = 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 microm and 
      volume of cornea (central 7 mm) expressed in mm3. 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 > or = 20/40. In the 
      first group (< or = -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 > or = 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 > or = 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 (> or = -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 > or = 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 microm and 
      ablated volume of central 7 mm cornea by 1 Dsph was 0.43 +/- 0.18 mm3. 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 microm and ablated volume 
      of central 7 mm cornea by 1 Dsph was 0.61 +/- 0.31 mm3. 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.
FAU - Resan, Mirko
AU  - Resan M
AD  - Klinika za ocne bolesti, Vojnomedicinska akademija, Beograd, Srbija. 
      resanm@ikomline.net
FAU - Vukosavljevic, Miroslav
AU  - Vukosavljevic M
FAU - Milivojevic, Milorad
AU  - Milivojevic M
LA  - srp
PT  - English Abstract
PT  - Journal Article
PL  - Serbia
TA  - Vojnosanit Pregl
JT  - Vojnosanitetski pregled
JID - 21530700R
SB  - IM
MH  - Adult
MH  - Female
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Myopia/physiopathology/*surgery
MH  - *Photorefractive Keratectomy/adverse effects
MH  - Refraction, Ocular
MH  - Visual Acuity
EDAT- 2012/11/20 06:00
MHDA- 2012/12/12 06:00
CRDT- 2012/11/20 06:00
PHST- 2012/11/20 06:00 [entrez]
PHST- 2012/11/20 06:00 [pubmed]
PHST- 2012/12/12 06:00 [medline]
AID - 10.2298/vsp1210852r [doi]
PST - ppublish
SO  - Vojnosanit Pregl. 2012 Oct;69(10):852-7. doi: 10.2298/vsp1210852r.