Analysis of refractive state after excimer laser photorefractive keratectomy in myopia]

OBJECTIVE: To evaluate refractive state after excimer laser photorefractive keratectomy (PRK) in patients with myopia. METHODS: 234 cases(391 eyes) followed up for two years were divided into two groups, group I: mild and moderate myopia(< or = -6.00 D), 228 eyes; group II: High myopia(> -6.00 D), 163 eyes. The refractive state of patients at three, six, twelve and twenty-four months postoperatively were monitored. RESULTS: At two years after photorefractive keratectomy (PRK), refractive regression (> -0.5 D), overcorrection(> 1.00 D), undercorrection(> 1.00 D), postoperative residual astigmatism postoperative astigmatism and hyperopia shift in group I were 1.7%, 4.4%, 5.7%, 12.8%, 7.4% and 7.5% respectively, while in high myopia group were 15.9%, 4.9%, 23.3%, 29.7%, 31.1% and 6.7% respectively. CONCLUSION: The results prove that photorefractive keratectomy is an effective, precise, stable and safe method for correction of mild and moderate myopia, but insufficient for high myopia.     

Effect of excimer laser repetition rate on outcomes after photorefractive keratectomy

PURPOSE: To compare the refractive outcomes after photorefractive keratectomy (PRK) for low to moderate myopic corrections using 2 excimer lasers with different repetition rates (200 Hz and 400 Hz). SETTING: University refractive surgery center. METHODS: This retrospective study included all consecutive patients who underwent PRK using the 200 Hz or the 400 Hz Allegretto laser platform (WaveLight Laser Technologie AG). Thirty-five patients (70 eyes) and 29 patients (58 eyes) had PRK with the 200 Hz platform and the 400 Hz platform, respectively, using the same surgical technique. RESULTS: The mean follow-up was 13.22 months +/- 1.16 (SD) (range 11 to 15 months). No intraoperative or early postoperative (eg, late reepithelialization) complications were found in either group. At 1 year, 66 eyes (94.2%) in the 200 Hz group and 56 eyes (96.6%) in the 400 Hz group were within +/-1.00 diopter of the attempted correction. At 3 months, 20 eyes (29%) in the 200 Hz group and 27 eyes (46%) in the 400 Hz group had mild or moderate corneal haze (P = .03). These corneas showed progressive clearing over subsequent months without statistically significant differences in haze formation between the 2 groups. Twelve months after PRK, all corneas in both groups were clear. CONCLUSION: Photorefractive keratectomy for the treatment of low to moderate refractive errors using a 200 Hz or 400 Hz excimer laser gave comparable results.     

Effect of beam variables on corneal sensitivity after excimer laser photorefractive keratectomy

AIM—To investigate changes in corneal touch sensitivity following excimer laser photorefractive keratectomy (PRK) using different beam configurations.
METHODS—20 subjects were given a unilateral −3.00 D correction with either a 5 mm (26 µm, n=10) or 6 mm (42 µm, n=10) beam diameter. Thirty subjects underwent a unilateral −6.00 D correction with 5 mm (62 µm, n=10), 6 mm (78 µm, n=10), or multizone (62 µm, n=10) treatments. The multizone treatment was 6 mm in diameter with the depth of the 5 mm treatment. Corneal sensitivity was measured using a slit-lamp mounted Cochet-Bonnet aesthesiometer before and at 1, 3, 6, and 12 months after PRK. Stimulus locations included points lying within the ablated zone (central) and outside (peripheral). These were compared with the equivalent locations in control (untreated) eyes.
RESULTS—There was a significant reduction in corneal sensitivity within the central (ablated) zone in all treatment groups after PRK. In most groups a return to full sensitivity was achieved by 6 months with the exception of the multizone treatment group which showed significant corneal hypoaesthesia at 12 months. Peripheral corneal sensitivity was also reduced in this group up to 3 months after the procedure. A comparison between the −3.00 D and −6.00 D treatment groups showed no significant difference. However, combining data from all treatment groups, a significant correlation was found between the interocular difference in central corneal sensitivity and postoperative haze at 3 and 6 months.
CONCLUSIONS—For corrections up to −6.00 D ablation depth and treatment zone diameter do not appear to be clinically important determinants of corneal hypoaesthesia. In contrast, postoperative corneal haze appears to correlate with sensitivity loss.

     

Corneal infiltrates after excimer laser photorefractive keratectomy and LASIK

PURPOSE: To determine the frequency and clinical characteristics of corneal infiltrates after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and to evaluate the efficacy of treatment. METHODS: We retrospectively reviewed the records of 8508 eyes treated with PRK or LASIK in a university-based clinic for the correction of refractive errors for 60 days postoperatively. RESULTS: Corneal infiltrates were observed in 35 (0.8%) of 4492 PRK-operated eyes and in 4 (0.1%) of 4016 LASIK-operated eyes. The mean time of diagnosis was 5.46 days. Among the 39 eyes with infiltrates, 10 (9 PRK, 1 LASIK) had culture-verified infectious keratitis. Coagulase-negative Staphylococcus was the most frequently isolated bacterium (50%), followed by S aureus (20%), Corynebacterium xerosis (10%), Streptococcus viridans (10%), and an unidentified gram-positive coccus (10%). Final visual acuity of > or = 20/30, without correction, was achieved in 79.5% of the 39 eyes. CONCLUSIONS: Corneal infiltrates occurred in 0.8% of PRK eyes and 0.1% of LASIK eyes. Bacterial smears were positive for several eyes. In all cases, prompt treatment was responsible for good visual outcome.     

准分子激光角膜切削术后角膜地形图的分析

目的：准分子激光角膜切削术（ＰＲＫ）后角膜性状和视力质量和研究。方法：对２３例（３８只眼）近视患者于术后１、３、６个月进行角膜地形图随访。结果：ＰＲＫ术后角膜表面的球面性状发生一定改变。随着时间推移，角膜表面规则指数（ＳＲＩ）和表面不规则指数（ＳＡＩ）均逐渐降低，角膜变得中平滑。模拟角计数数表现一定的回退。术后６个月时，角膜地形图主要表现为四种形态；圆形或椭圆形、哑铃形、半环形、中央小岛形、有珞种     

Enhancement outcomes after photorefractive keratectomy and laser in situ keratomileusis using topographically guided excimer laser photoablation

PURPOSE: To evaluate the efficacy and safety of topographically guided excimer laser photoablation to retreat unsuccessful myopic and hyperopic photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Eye Clinic, San Salvatore Hospital, University of L'Aquila, L'Aquila, Italy. METHODS: At least 3 months after primary PRK (Group A) or primary LASIK (Group B), 48 eyes of 42 patients were submitted to PRK or LASIK enhancements. The eyes were treated with an excimer laser linked to a computerized videokeratography unit with a topographically supported customized ablation workstation. RESULTS: The mean follow-up was 27.8 months +/- 8.2 (SD). In Group A, the uncorrected visual acuity (UCVA) changed from 0.5 +/- 0.7 logarithm of the minimum angle of resolution (logMAR) (range 20/600 to 20/200) to 0.1 +/- 0.7 logMAR (range 20/60 to 20/20); the mean best spectacle-corrected visual acuity (BSCVA) changed from 0.1 +/- 0.7 logMAR (range 20/50 to 20/20) to 0 +/- 0.7 logMAR (range 20/50 to 20/20) after the enhancement. In Group B, the UCVA changed from 0.7 +/- 0.8 logMAR (range 20/600 to 20/40) to 0.1 +/- 0.7 logMAR (range 20/40 to 20/20); the mean BSCVA improved from 0.2 +/- 0.8 logMAR (range 20/30 to 20/20) to 0 +/- 1.3 logMAR (range 20/25 to 20/20) after surgery. CONCLUSIONS: The enhancements using topographically guided excimer laser photoablation with a topographically supported customized ablation method resulted in satisfactory and stable visual outcome with good safety and efficacy after unsuccessful PRK and LASIK.     

PRK术后角膜上皮下雾状混浊的相关因素分析

为探讨准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）后角膜上皮下雾状混浊（ｈａｚｅ）的原因及影响因素，对ＰＲＫ后６个月时屈光度在－１．００～－１８．５０Ｄ的３１６例（６１５只眼）近视眼的ｈａｚｅ相关因素进行观察和比较。结果：ＰＲＫ后６个月时ｈａｚｅ发生率为４４．７％，１级或以上ｈａｚｅ为１３．３％。ｈａｚｅ的发生率及密度随屈光度增高而增加（Ｐ＜０．０００１），也随切削深度的增加而增加（Ｐ＜０．０００１），术前非接触眼压超过１８ｍｍＨｇ者，ｈａｚｅ的发生率和密度增加（Ｐ＜０．００５），男性较易发生ｈａｚｅ（Ｐ＝０．０００１），与年龄呈负相关（Ｐ＜０．０５）。而角膜厚度、术前戴用接触镜及散光对ｈａｚｅ的影响不显著。结论：高度近视（＞－６．０Ｄ）和过深的切削（＞８０μｍ）是引起ｈａｚｅ的主要原因。术前眼压偏高、年龄偏低对ｈａｚｅ也有明显影响。对ＰＲＫ治疗高度近视应持审     

准分子激光屈光性角膜切削术对角膜内皮细胞的影响

目的 探讨分析准分子激光屈光性角膜切削术（ＰＲＫ）治疗近视后对角膜内皮细胞的影响。方法 对１０１只眼ＰＲＫ术后者,用接触型镜面反光角人皮显微镜（Ｋｏｎａｎ ＳＰ－３５００型,日本）检测不同部位角膜内皮细胞,并统计分析其在不同度数范围内的平均细胞密度、细胞面积的变异系数和六角形细胞的百分率。结果 平均细胞密度在Ｃ组上降１０％,Ａ,Ｂ组的下降无统计学意义。细胞面积的变异系数及六角形细胞百分率均下降１０     

Natural history of corneal topography after excimer laser photorefractive keratectomy

Purpose

To investigate the natural history of corneal topography after excimer laser photorefractive keratectomy (PRK).

Design

A prospective, single center clinical study.

Participants

A total of 40 eyes of 34 patients with myopia were studied.

Intervention

Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed.

Main outcome measures

Preoperative, 1 week, and 1,2, and 3 months postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite “average” topography maps.

Results

Corneal topography was generally not homogeneous at 1 week after PRK. By 3 months, there had been considerable smoothing of corneal contour. A general “central island” effect early in the postoperative period flattened over time. When right and left eyes were evaluated independently, a tendency toward a keyhole-semicircular pattern was seen on average; the maximum flattening was nasal and the least flattening was inferotemporal for both right and left eyes.

Conclusions

A tendency, on average, toward central island and keyhole-semicircular patterns is seen early in the postoperative course after PRK. Central islands tend to evolve into the keyhole-semicircular pattern, and the corneal topography in general after PRK tends to smooth considerably with time.     

Effect of ablation profile on wound healing and visual performance 1 year after excimer laser photorefractive keratectomy.

BACKGROUND: Early photorefractive keratectomy ablations were of limited diameter and depth to maintain the integrity of the globe and to minimise postoperative haze. This study evaluated the effects of deeper, larger diameter wounds on refractive stability and corneal haze, and investigated the effects of ablation profile on wound healing and visual performance. METHODS: One hundred patients undergoing -3.00D and -6.00D corrections were randomised to receive 5 mm, 6 mm, or multizone treatments. The multizone treatment was 6 mm in diameter, but only the depth of the 5 mm treatment. Outcome was measured by Snellen visual acuity, residual refractive error, objective techniques for haze and halos, pupil diameter, subjective night vision, and requirement for retreatment. RESULTS: Overall, the results of 6 mm treatments were superior to those of 5 mm and multizone treatments: they had a smaller hyperopic shift (p < 0.01), a more predictable (p < 0.001) and stable refractive outcome, less haze (p < 0.05), smaller halos (p < 0.05), fewer subjective night vision problems, and fewer patients required retreatment. CONCLUSIONS: Analysis of these data and a literature review of corneal wound healing demonstrated that the improved outcome associated with the 6 mm beam did not relate to the depth of ablation. The factor with greatest apparent influence on the development of haze and regression was the slope of the wound surface over the entire area of the ablation. Tapering the wound edge provided no additional benefit, and contributed to night vision problems. It is, therefore, recommended that small diameter or multizone treatments should not be used in low and moderate myopia.     

Effect of excimer laser beam delivery and beam shaping on corneal sphericity in photorefractive keratectomy

PURPOSE: To evaluate the impact of beam delivery and beam shaping on corneal profiles after myopic excimer laser photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Charité-Campus Virchow Hospital, Humboldt University of Berlin, Berlin, Germany. METHODS: Standard myopic 193 nm excimer laser PRK of -3.0 diopters (D) and -6.0 D was performed in porcine eyes using 2 commercially available broad-beam lasers with band-mask and fractal-mask beam shaping, 2 flying-spot lasers, and a scanning-slit laser. A silicone replica was obtained to preserve the corneal profile and was measured with a dynamic focusing topometry system. RESULTS: The scanning-slit and flying-spot lasers created uniform profiles comparable to those in an untreated control group. Both broad-beam lasers with band-mask and fractal-mask beam shaping created central islands and paracentral profile valleys of 15.10 microm and 17.00 microm maximum height after -3.0 D PRK and 26.45 microm and 24.31 microm after -6.0 D PRK. An anti-central-island program, which applied a series of laser pulses centrally to compensate for the central profile elevations, did not eliminate the islands. Stromal surface roughness increased with ablation depth and was significantly worse after scanning-slit ablation than after broad-beam ablation. CONCLUSIONS: Laser-induced deviations from the intended uniform corneal profiles were associated with broad-beam ablation and increased ablation depth and therefore lessened the predictability of the refractive outcomes. Scanning-slit and flying-spot systems produced predictably uniform corneal profiles.     

Wavefront-guided excimer laser ablation using photorefractive keratectomy and sub-Bowman's keratomileusis: a contralateral eye study

PURPOSE: To explain the basic science and clinical evidence that has led to the development of a new technique in corneal refractive surgery--sub-Bowman's keratomileusis (SBK). METHODS: A comprehensive review of the literature and report of a contralateral eye study of 50 patients (100 eyes) enrolled at 2 sites (25 patients per site) and randomized according to the dominant eye was conducted. All eyes underwent a wavefront-guided refractive correction using the Alcon LADARVision4000 System. In one eye, an 8.5-mm, ETOH-assisted photorefractive keratectomy (PRK) was performed. In the second eye, an 8.5-mm, 100-microm flap was attempted using a 60 kHz IntraLase FS femtosecond laser. Pre- and postoperative tests included best spectacle-corrected visual acuity, uncorrected visual acuity, corneal topography, wavefront aberrometry, retinal image quality, contrast sensitivity, and biomechanical response of the cornea. Patients completed subjective questionnaires at each follow-up. RESULTS: Clinical results demonstrate that SBK provides quicker visual recovery, although the data suggest that the 3- and 6-months results are similar in terms of visual outcomes. Reichert Ocular Response Analyzer results demonstrate that its impact on the cornea is similar to PRK. CONCLUSIONS: This study indicates that SBK provides the visual recovery of a LASIK procedure with the Optical Response Analyzer results similar to PRK.     

Late natural history of corneal topography after excimer laser photorefractive keratectomy

PURPOSE: To investigate the 3 month to 1 year natural history of corneal topography after excimer laser photorefractive keratectomy (PRK). DESIGN: A prospective, multicenter, nonrandomized comparative study. PARTICIPANTS: A total of 75 eyes of 68 patients with myopia were studied. INTERVENTION: Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed. MAIN OUTCOME MEASURES: Preoperative and 3, 6, and 12 month postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite "average" topography maps. RESULTS: Corneal topography was relatively smooth 3 months after PRK. By 12 months, the corneal contour in general had become even more uniform. No "central island" effect was observed. When looking at right and left eyes independently, there was a tendency toward maximum flattening nasally. CONCLUSIONS: Corneal topography in general continues to smooth from 3 to 12 months after PRK, possibly as a result of epithelial and stromal healing and remodeling. Right and left eyes on average show mirror-image, spatially oriented topography patterns.     

Corneal topography of small-beam tracking excimer laser photorefractive keratectomy.

PURPOSE: To evaluate the topographic characteristic of photorefractive keratectomy (PRK) for low myopia performed with a small-beam (0.9 mm) tracking excimer laser. SETTING: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine in New Orleans, and the Refractive Surgery Center of the South at the Eye, Ear, Nose, & Throat Hospital, New Orleans, Louisiana, USA. METHODS: Sixty-seven eyes of 47 patients had PRK with a small-beam tracking laser. Of these, 49 eyes had data permitting evaluation of ablation centration; usable data for topographic analysis were available for 59 eyes preoperatively, 54 eyes at 1 month, 42 eyes at 3 months, and 25 eyes at 6 months, permitting measurement of various topographic parameters, including the cylinder (CYL), average corneal power (ACP), surface regularity index (SRI), surface asymmetry index (SAI), corneal eccentricity index (CEI), and coefficient of variation of corneal power (CVP). RESULTS: Preoperatively, all eyes were topographically normal. Postoperatively, no eye exhibited a "central island" by even the least-restrictive definition, and all eyes had best spectacle-corrected visual acuities (BSCVAs) of 20/20 or better at all follow-ups. Mean decentration of the ablations from the pupil centers was 0.42 mm +/- 0.28 (SD) (n = 49). There was no correlation between measured decentration and BSCVA (P = .46). The central cornea was flattened (decreased ACP; P < .001) and made oblate (decreased CEI; P < .001) as expected. There was no increase in SRI or SAI (irregular astigmatism) at 6 months compared with preoperative values (P = .91); however, CYL and CVP (varifocality) increased slightly (P = .04 and .02, respectively). CONCLUSION: The absence of significant regular or irregular astigmatism 6 months after PRK with the small-beam laser is an improvement over published results achieved with wide-beam lasers and is consistent with the excellent visual acuity results in this cohort.     

Glare sensitivity and visual acuity after excimer laser photorefractive keratectomy for myopia

BACKGROUND—Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors.
METHODS—Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression.
RESULTS—One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months.
CONCLUSION—Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications.

     

Corneal optical coherence tomography before and immediately after excimer laser photorefractive keratectomy

PURPOSE: To investigate the representation of the corneal structure with optical coherence tomography before and immediately after excimer laser photorefractive keratectomy. METHODS: Twenty-four eyes of 24 patients with myopia and myopic astigmatism were prospectively studied. The corneal thickness and the corneal profile were assessed with slit-lamp-adapted optical coherence tomography preoperatively and immediately after excimer laser photorefractive keratectomy. RESULTS: The attempted mean spherical equivalent of the refractive corrections was -6.7 +/- 3.6 (mean +/- SD) diopters with a mean calculated stromal ablation depth of 91 +/- 38 microm. The corneal optical coherence tomography was reproducible in all patients, demonstrating a mean decrease of central corneal thickness after epithelial debridement and excimer laser photorefractive keratectomy of 118 +/- 45 microm. The comparison of the calculated stromal ablation depth and the corneal thickness changes determined by corneal optical coherence tomography revealed a significant linear relationship with a correlation coefficient of 0.88 (P <.001). The flattening of the corneal curvature was confirmed in all patients with the optical coherence tomography system and correlated with the attempted refractive correction (r =.82, P <.001). CONCLUSIONS: The slit-lamp-adapted optical coherence tomography system presented in this study allowed noncontact, cross-sectional, and high-resolution imaging of the corneal configuration. This initial clinical evaluation demonstrated that corneal optical coherence tomography could be a promising diagnostic modality to monitor corneal changes of thickness and curvature before and after excimer laser photorefractive keratectomy.     

准分子激光角膜切削术后散光的角膜地形图分析

了解准分子激光角膜切削术（ｐｈｏｔｏｇｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）前、后最大轴性散光的变化及对术后视力的影响。方法对ＰＲＫ后１年以上的６１例（１０９只眼）术前散瞳验光散光度一１．００～－２．００Ｄ的角膜地形图进行分析及视力检查。结果散瞳验光散光轴位与地形图记录散光轴位基本一致，而散光度数有一定差异。地形图检查显示，最大散光轴位以循规性极光最多，计６７只眼（６１％），斜轴性散光３６只眼（３３％），逆规性散光６只眼（６％）。手术前、后散光轴位变化极小。散光度多数在术后１０天及１个月开始增加，以后逐渐减少。６个月或１年趋于稳定。术后的残存散光对视力影响较小，实际矫正度在预期矫正度±１．００Ｄ以内者占９７％。结论采用球柱折算方法，进行ＰＲＫ，对矫正近视合并散光者（－２．００Ｄ以下），可以获得满意的屈光矫正。     

Short-term oxidative status of lens and aqueous humor after excimer laser photorefractive keratectomy

PURPOSE: Oxidation in the anterior ocular segment is associated with cataractogenesis and possible complications to corneal endothelium. We investigated whether oxidation occurred in the rabbit anterior ocular segment shortly after excimer laser photorefractive keratectomy (PRK). METHODS: Rabbits were treated unilaterally with PRK, the other eye serving as a control. Aqueous humor sampled shortly after treatment was assayed spectrophotometrically for hydrogen peroxide using ferrous oxidation in xylenol in the presence (group 1; n=10), or absence of oxygen (group 2; n=8). Oxidized glutathione and malondialdehyde levels were measured in lenses by spectrophotometry and HPLC. RESULTS: Hydrogen peroxide concentration of aqueous humor was not different between treated (77 +/- 36 microM) and control eyes (88 +/- 34 microM) in the oxygen group or the nonoxygenated group (treated eyes: 6.7 +/- 5.4 microM and control eyes: 5.5 +/- 4.7 microM). Peroxide levels did not correspond to endogenous H2O2 but presumably reflected action on ascorbic acid. There was no difference in the percent of oxidized glutathione between experimental and control eyes. Malondialdehyde could not be detected in the lens of treated or control eyes, despite good sensitivity in recovery assays. CONCLUSION: Based on these assays, there is no evidence that PRK oxidizes the aqueous humor or the lens of treated rabbits within 10 minutes of treatment.     

Diadenosine polyphosphates after laser in situ keratomileusis and photorefractive keratectomy refractive techniques

Purpose: To study the concentrations of diadenosine polyphosphates in the ocular surface after PRK and LASIK. Methods: Sixty‐one patients (30 males and 31 females) with ages ranging from 20 to 63 (34.04 ± 9.13 years) were recruited in Balear Institute of Ophthalmology, Palma de Mallorca, Spain. LASIK was performed in 92 eyes of 46 patients and PRK in 25 eyes of 15 patients. Variations in the levels of diadenosine polyphosphate (Ap₄A and Ap₅A), Schirmer I (Jones test), TBUT, corneal staining together with the Dry Eye Questionnaire to evaluate discomfort and dryness were studied. All tests were performed at the preoperative visit and at 1‐day, 2‐week, 1‐month and 3‐month postoperative visits. Results: Ap₄A showed a 5 and 3.5 fold increase at the 1‐day visit for LASIK and PRK, respectively. LASIK patients continued having higher statistically significant concentrations (p = 0.01) all over the follow‐up. Ap₅A showed no significant differences at any visit. Tear volume decreased during the 3 months in LASIK. The PRK cases had a normal volume at 1 month. TBUT in LASIK increased at the 1‐day visit (p = 0,002) and decreased from the 2 weeks onwards and for the PRK, decreased by a 35% at the 1‐day visit and kept reduced for a month. Discomfort only increased at the 1‐day visit (p = 0.007). Dryness frequency was similar in all visits. Conclusions: Ap₄A levels only are increased in refractive surgery patients during the first day after the surgery. This increasing suggests that Ap₄A may help accelerating the healing process.