Keratorefractive surgery practice in a tertiary eye care center in central India / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To study the patient characteristics and keratorefractive surgery(KRS)practice in central India.METHOD: The retrospective study was conducted on 410 patients who underwent KRS from June 2017 to April 2022 at a tertiary eye care center in central India. Demographic data of the patients presenting for the spectacle free vision like age, sex, residence in the form of urban or rural area, refractive error, cause for spectacle-free vision, best-corrected visual acuity, types of procedure, postoperative follow-up and complications were recorded.RESULTS: Among the 410 patients who presented for spectacle-free vision, 324 patients were considered for KRS(79.0%), and 200 patients(61.7%)underwent the laser-assisted in situ keratomileusis(LASIK)procedure, whereas 124 patients(38.3%)underwent the photorefractive keratectomy(PRK)procedure. The final study group comprised 179 female and 145 male. The mean age of the patients was(25±3.5)years. A majority of patients were from urban areas(n=250, 77.2%). The mean preoperative manifest refraction in the right and left eyes was -4.5±2.1 and -4.9±2.0, respectively. The mean surgical time in the LASIK patient was(15±2)min and(17±3)min for both eyes in PRK. None of the patients exhibited epithelial ingrowth, flap healing complications, or infection, and none of them required enhancement. Suboptimal corneal thickness(n=28, 32.6%)was the most common reason for rejection. At the end of the 1-year follow up, 3 patients who underwent the LASIK procedure exhibited regression(-0.5 D±1 D), with a refractive error correction of -6.75 D, -8.5 D, and -7.0 D, respectively.CONCLUSION: LASIK is the predominant procedure for the correction of refractive error in the central Indian population. Although the number of PRK procedures was small, both LASIK and PRK exhibited excellent visual outcome. Myopic regression should be considered when choosing LASIK for high myopia.

Visual quality observation of transepithelial photorefractive keratectomy and femtosecond small incision lenticule extraction for the correction of low myopia / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To observe the changes in corneal aberrations and the characteristics of visual quality after transepithelial photorefractive keratectomy(T-PRK)and femtosecond small incision lenticule extraction(SMILE)in the correction of low myopia.METHODS: Prospective cohort study. A total of 32 cases(32 eyes)with low myopia who underwent T-PRK surgery and 45 cases(45 eyes)of SMILE surgery at Weifang Eye Hospital from April 2021 to April 2022 were selected. The uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), spherical equivalent(SE), corneal higher-order aberrations(HOAs)and objective visual quality were compared between the two groups.RESULTS:All patients completed the surgery successfully without complications such as infection. At 3mo postoperatively, the safety index was 1.13±0.16 and 1.16±0.17(P=0.48)and the efficacy index was 1.10±0.20 and 1.15±0.18(P=0.27)in the T-PRK and SMILE groups, respectively. The percentage of UCVA(LogMAR)≤0 in the T-PRK and SMILE groups was 94% and 98%, respectively. The percentage of the residual SE within ±0.5D was 88% and 87% in the two groups, respectively. The HOAs and spherical aberration in both groups were significantly increased(P≤0.01), and the increase was not statistically significant between the two groups(P=0.31, 0.89). There was no significant change in horizontal coma, horizontal trefoil and vertical trefoil in both groups(P>0.05). The vertical coma in SMILE group was significantly increased(P<0.001), while there was no significant change in T-PRK group(P>0.05), and the increase was significantly greater in SMILE group than in T-PRK group(P<0.001). There was no significant difference in objective scattering index(OSI), modulation transfer function cut off frequency(MTFcut off), Strehl ratio(SR), visual acuity(VA)100%, VA20% and VA9% between the two groups(P>0.05).CONCLUSION:Both T-PRK and SMILE showed good safety, efficacy, and visual quality in correcting low myopia, while SMILE induced more vertical coma than T-PRK.

Impact of teleconsultation on visual and refractive outcomes in patients undergoing laser refractive surgery during COVID-19

Purpose: To assess the role of remote teleconsultation (TC) follow?up care following a successful and uneventful laser vision correction. Methods: The study is a retrospective, comparative analysis of patients undergoing laser vision correction at tertiary care eye hospital in Southern India. The patients were divided into two groups. The first group included patients operated on before the coronavirus disease (COVID?19) pandemic and were followed up with physical consultations during their follow?up visit (Group 1). The second group comprised patients operated on during the pandemic and had at least one remote TC during their post?operative follow?up (Group 2). Results: A total of 1088 eyes of 564 patients and 717 eyes of 372 patients were included in Group 1 and 2, respectively. The mean number of visits for the patients from Group 2 during the COVID period (2.56 +/? 0.74 days) was significantly lesser (P < 0.0001) than that of Group 1 in the pre?COVID period (3.53 +/? 1.07 days). Close to 90% of the eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 in both groups (P = 0.925). 96.50% of the eyes in Group 1 and 98.18% of the eyes in Group 2 achieved UCVA 20/25 or better (P = 0.049). Eight eyes (0.73%) in Group 1 and one eye (0.14%) in Group 2 reported a loss of 2 or more lines. However, the results were not statistically significant (P = 0.156). None of the groups had any patients who had a sight?threatening complication. Conclusion: Remote TC following refractive surgery is safe and can be effectively integrated into routine refractive practice to reduce travel to the hospital for a physical consult

Effect of Trans-PRK combined with 0.02% MMC on corneal density in patients with moderate myopia / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To evaluate the effect of 0.02% mitomycin-C(MMC)on the corneal density after transepithelial photorefractive keratectomy(Trans-PRK). METHODS: Retrospective case analysis. Selected 28 patients with 56 eyes in moderate myopia who underwent Trans-PRK surgery from January 2021 to June 2021 in our hospital. They were divided into MMC group in 28 eyes with a combination of 0.02% MMC 20s during the surgery and the control group in 28 eyes was not use MMC during the surgery. The Pentacam anterior segment analyzer was used to measured the corneal density in different diameter ranges and different thickness layers before and after surgery at 14d, and after surgery at 1 and 3mo.RESULTS: The total corneal density value of MMC group was 16.60(15.70,17.10 )before the surgery, after the surgery at 14d was 16.63(15.90,17.50 ), at 1mo was 16.57(15.10,16.70 ), at 3mo was 16.04(14.60,16.60 ). The total corneal density value of control group was 16.30(15.50,17.30 )before the surgery, after the surgery at 14d was 16.20(15.20,17.10 ), at 1mo was 16.08(14.90,16.40 )and at 3mo was 15.60(14.60,16.40 ). In the zone of 0-2mm diameter was centered on the corneal vertex, the corneal density of the two groups at 14d after the surgery was higher than those before surgery(P<0.001 ). In the zone of 2-6mm diameter, the corneal density of the two groups at 1mo and 3mo after surgery was higher than those before the surgery(P<0.001). In the zone of 6-10mm, the corneal density of the two groups at 14d, 1 and 3mo after surgery was higher than those before the surgery(P<0.001). In the layer of anterior 120 μm, the corneal density of the two groups at 1mo and 3mo after the surgery was decreased than that before surgery(P<0.01). In the middle layer, the corneal density of the two groups at 1mo after the surgery was decreased than those before surgery(P<0.01).CONCLUSION:The use of 0.02% MMC during the operation can reduce the corneal density and increase the corneal light transmittance in the early postoperative period. The occurrence and prognosis of haze can be effectively quantified by observing the changes of corneal optical density in different ranges in different time periods after operation.

Laser topoguiado como tratamento de ectasia pós lasik / Topoguided laser as treatment of ectasia after lasik

RESUMO O laser in situ keratomileusis (LASIK) é o método cirúrgico refrativo mais realizado no mundo com excelentes resultados, porém tal método não é isento de riscos. A ectasia pós LASIK é uma complicação grave e se caracteriza por um aumento progressivo da curvatura e afinamento da córnea, resultando em astigmatismo irregular e diminuição da acuidade visual. Sua incidência na literatura atual é de aproximadamente 0,033%. O principal tratamento dessa complicação é o implante de anel intra-estromal com cross-linking. Neste artigo descrevemos um caso de uma mulher de 45 anos submetida a sucessivas tentativas de tratamento de ectasia pós LASIK, com implante de anel intra-estromal bilateral, sem sucesso em um dos olhos. Foi feito o uso do excimer laser topoguiado através do photorefractive keratectomy (PRK) sem o cross-linking, que optamos por não realizar pela estabilidade há anos, pelo risco alto de haze e pela ablação apenas na lamela (que era espessa).A paciente obteve melhorasignificativa da visão e da qualidade de vida. Mantemos o acompanhamento a cada seis meses desde então com a tomografia da córnea.

ABSTRACT The laser in situ keratomileusis (LASIK) is the most widely used refractory surgical method in the world with excellent results, but this method is not without risks. Post-LASIK ectasia is a serious complication and is characterized by a progressive increase in curvature and thinning of the cornea, resulting in irregular astigmatism and decreasing visual acuity. Its incidence in the current literature is approximately 0.033%. The main treatment for this complication is the implantation of an intra-stromal ring with crosslinking. In this article, we describe a case of a 45-year-old woman who underwent successive attempts to treat post-LASIK ectasia, with bilateral intra-stromal ring implantation, with no success in the eyes. Excimer laser was used, made through photorefractive keratectomy (PRK) without cross-linking and the patient obtained significant improvement in vision and in quality of life.

Comparison of Intraocular Lens Calculation Formulas for Phacoemulsification after corneal refractive surgery in asian eyes

@#OBJECTIVE: To compare the different intraocular lens (IOL) calculation formulas available on the American Society of Cataract and Refractive Surgery (ASCRS) IOL power calculator website among Asian eyes with previous corneal refractive surgery. METHODS: A retrospective cohort study of 84 eyes in 68 Asian patients who had phacoemulsification with previous LASIK or photorefractive keratectomy (PRK) was done. Using the post-phacoemulsification manifest refraction spherical equivalent (MRSE) as target refraction, IOL prediction error (PE) for each formula was calculated as the implanted minus the predicted IOL power. Refractive PE was determined by calculating that 1 diopter (D) of IOL PE produces 0.7 D of refractive error at the spectacle plane. RESULTS: Comparing the Shammas, Haigis-L, Barrett True-K No History, ASCRS Average IOL Power No History, Barrett True-K, and ASCRS Average IOL Power with Change in Manifest Refraction (ΔMR), the mean IOL PEs ranged from -0.23 to -0.62 D, with the Barrett True-K having the lowest PE. The median refractive PEs for all formulas were similar at 0.35 D, except for the Haigis-L at 0.53 D. The ASCRS average with ΔMR had a statistically higher percentage of eyes within 0.5 D of target refraction versus other formulas (p<0.05). The Haigis-L IOL PE and refractive PE were significantly higher than the Barrett True-K (p<0.001), and the ASCRS average with ΔMR (p<0.001) respectively. The ASCRS average with ΔMR produced a significantly smaller variance of IOL PE (p<0.05). CONCLUSION: Accounting for PEs and variance, the ASCRS average IOL power with ΔMR is recommended, followed by the ASCRS average IOL power No History if without historical data.

Effect of sunlight exposure on cornea in infant rhesus monkeys with monocular hyperopic defocus induced by PRK / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To observe whether exposure to natural light causes damage on corneal tissue in infant rhesus monkeys with monocular hyperopic defocus induced by PRK. <p>METHODS: Twelve infant rhesus monkeys(aged 2mo)were treated monocularly with PRK(-4.0D)and divided into two groups: AL group(<i>n</i>=6)and NL group(<i>n</i>=6). The monkeys in AL were reared under artificial lighting(indoor).The monkeys in NL were exposed to natural lighting(outdoor)for 4h per day(9:00-11:00 and 15:00-17:00), and to indoor lighting for the rest of the light phase. Corneal haziness after PRK was assessed biomicroscopically using the Fantes scale. At 50d post-PRK, tear fluids of both eyes from 8 monkeys in the two groups(4 animals each group)were collected and analyzed for 11 kinds of cytokines using protein microarray analysis. At 180d post-PRK. The corneas were obtained and evaluated by histopathological examination, immunohistochemistry with antibody to TGF-β1 and α-SMA, and TUNEL. The vitality of SOD and the level of MDA in corneas were detected with WST-1 and lipid peroxidation MDA assay kits, respectively.<p>RESULTS: The monkeys in AL group exhibited a lesser degree of haze than those in NL group at 40d following PRK(<i>P</i>=0.015). At 50d post-PRK, EGF and TGF-β1 levels in tears were different in PRK-treated eyes between the two groups(<i>P</i>=0.045, 0.038), and TGF-β1 were significantly different between both eyes in the same group(AL: <i>P</i>=0.003; NL: <i>P</i>=0.036). At 180d post-PRK, there were no differences in histological changes, the expression of TGF-β1 and α-SMA, and apoptosis cell staining of the corneal between the two groups. The vatility of SOD and the levels of MDA in corneal epithelium were not different between the two groups(<i>P</i>>0.05).<p>CONCLUSION: Exposure to natural light in our study could not induce light damage to the normal cornea of the infant rhesus monkeys, but it could aggravate the corneal tissue repair reaction transiently post-PRK.

Intraocular lens power calculation in eyes with previous LASIK/PRK / 国际眼科杂志(Guoji Yanke Zazhi)

@#Calculating the intraocular lens(IOL)power in eyes with prior corneal refractive surgery(LASIK/PRK)is still a challenging task for all cataract ophthalmologists. The accuracy of the IOL power calculating is lower than virgin eyes, because the three generation formulae and traditional corneal instruments which measure central corneal radius of curvature in the paracentral 2.5-3.2mm zone are incorrect after myopic refractive surgery. There are three main sources of error in IOL calculation after refractive surgery: the radius measurement error, the keratometer index error and the IOL formula error. The purpose of the present paper is to describe the different available techniques to improve the accuracy of the IOL power calculation after refractive procedures.

LASIK, SMILE and PRK:advantages and indications / 国际眼科杂志(Guoji Yanke Zazhi)

@#Photorefractive keratectomy(PRK), laser-assisted <i>in situ</i> keratomileusis(LASIK)and small-incision lenticule extraction(SMILE)are the most clinically effective and safe techniques, for refractive surgery. All three kinds of laser vision correction, while varying in technique, have roughly a similar high achievement rate. Which method is best for you to rely upon various components like the refractive error, habits and profession, for example, sports and lifestyle. LASIK is as of now the predominant strategy in refractive surgery but SMILE also spreads rapidly between surgeons. This increments comfort amid the early postoperative period, takes into account quick visual recovery, and diminishes the wound healing response. And additionally that there would be less postoperative dry eye after SMILE contrasted with LASIK because the anterior stroma is exasperates just by the small incision, implying that the anterior corneal nerves ought to be less influenced. SMILE likewise lower induction of higher order aberrations(HOA)contrasted with LASIK and PRK. No contrasts between SMILE, LASIK and PRK medicines in postoperative corneal hysteresis(CH)corneal resistance factor(CRF)or corneal hysteresis values. PRK, but, remains a supreme option for moderate to mild modifications, especially for cases involving thin corneas, frequent erosions.

Non-topography-guided photorefractive keratectomy combined with accelerated collagen cross linking for treatment of keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the visual, refractive and clinical outcomes of non-topography-guided photorefractive keratectomy(PRK)and corneal collagen cross linking(CXL)in eyes with keratoconus.<p>METHODS: Totally 34 cases were evaluated for uncorrected distance visual acuities(UDVA)and corrected distance visual acuities(CDVA), flat and steep keratometry readings, and complications were evaluated at 1mo, 3mo, 6mo and 12mo postoperatively.<p>RESULTS: Thirty-four patients with mean age of 23.3±4.0 years. Statistically significant improvement was shown in UCVA and CDVA, with steadiness of refection for 1y postoperative. <i>T</i>-test showed a significant difference(<i>P</i><0.05)in all means between the preoperative and postoperative values(visual acuity, spherical and cylinder changes), with stability over a 1y follow up. Fourier analysis of postoperative images showed an axis shift perpendicular to the preoperative axis.<p>CONCLUSION: Simultaneous non-topography-guided PRK and CXL is safe and effective surgical alternative for keratoconus, yielding improvement in the UDVA, CDVA, and refractive status. Stabilization was achieved as early as 3mo after surgery, the only advantage of topography-guided over non-topography-guided PRK might be the minimal over correction of sphere and the cylindrical axis shift in some patients as detected by Fourier analysis of postoperative pentacam.

LAMMER Kinase Lkh1 Is an Upstream Regulator of Prk1-Mediated Non-Sexual Flocculation in Fission Yeast

The cation-dependent galactose-specific flocculation activity of the Schizosaccharomyces pombe null mutant of lkh1⁺, the gene encoding LAMMER kinase homolog, has previously been reported by our group. Here, we show that disruption of prk1⁺, another flocculation associated regulatory kinase encoding gene, also resulted in cation-dependent galactose-specific flocculation. Deletion of prk1 increased the flocculation phenotype of the lkh1⁺ null mutant and its overexpression reversed the flocculation of cells caused by lkh1 deletion. Transcript levels of prk1⁺ were also decreased by lkh1⁺ deletion. Cumulatively, these results indicate that Lkh1 is one of the negative regulators acting upstream of Prk1, regulating non-sexual flocculation in fission yeast.

Comparison of 10-year Clinical Results between Laser in situ Keratomileusis and Surface Ablation for Moderate to High Myopia

PURPOSE: To compare the long-term prognosis of laser in situ keratomileusis (LASIK) and surface ablation in moderate to high myopia. METHODS: A retrospective study including 87 eyes of 44 myopic patients treated with LASIK or surface ablation from 1995 to 2005 was performed. Follow-up visits were performed at 3 months, 1 year, 5 years, and 8 years. All treated eyes were divided into 2 groups according to preoperative spherical equivalent (SE)- moderate myopia (<-6.0 diopters [D]) and high myopia (≥-6.0 D). The main outcome measures were postoperative uncorrected visual acuity (UCVA), best corrected visual acuity, SE, mean keratometry, safety index, efficacy index, predictability, and complications. RESULTS: Mean SE was -7.05 ± 2.49 D in the LASIK group and -5.25 ± 1.23 D in the surface ablation group. The 10-year SE was -1.78 ± 1.22 D in the LASIK group and -1.35 ± 1.09 D in the surface ablation group, and there was no statistical difference between the 2 groups. At 10 years postoperatively, UCVA was log MAR 0.155 ± 0.161 in the LASIK group and log MAR 0.095 ± 0.140 in the surface ablation group. There were no significant differences in postoperative mean SE, safety index, efficacy index, or complications between the LASIK and surface ablation group at 10 years. CONCLUSIONS: This 10-year follow-up study shows that LASIK and surface ablation for moderate to high myopia have no statistical differences in mean SE, safety index, efficacy index, or complications.

Higher-Order Aberrations and Visual Acuity with Wavefront-Guided and Wavefront-Optimized Ablation in Laser Keratorefractive Surgery

PURPOSE: To compare higher-order aberrations (HOAs) and visual acuity after wavefront-guided and wavefront-optimized laser keratorefractive surgery. METHODS: This retrospective study consisted of consecutive cases of eyes that underwent wavefront-guided (VISX S4 CustomVue(R)) or wavefront-optimized (WaveLight(R) EX500) laser assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Preoperative and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction spherical equivalent (MRSE), and preoperative and 3 month postoperative HOAs were compared. RESULTS: There were no statistical differences in UCVA, BCVA, MRSE, or total HOAs in either the LASIK and PRK groups (all p > 0.05). Induced amount of spherical aberration (SA) was significantly lower in the wavefront-optimized LASIK and PRK than wavefront-guided LASIK and PRK. CONCLUSIONS: In laser keratorefractive surgery, wavefront-guided and wavefront-optimized platforms produced equivalent visual outcomes and no differences in total HOAs. However, the wavefront-optimized platform caused less spherical aberration 3 months after operation.

Effects of Topical Tranilast on Corneal Haze with the Pentacam(R) after Photorefractive Keratectomy

PURPOSE: To evaluate the inhibitory effect of tranilast on formation of corneal haze using the Pentacam(R) after photorefractive keratectomy (PRK). METHODS: A prospective, randomized, paired eye study was performed. A total of 60 eyes from 30 patients were enrolled in the present study. Eyes were categorized as myopic eyes or =-5 D. Patients undergoing PRK were randomized to receive tranilast in one eye and no medication in the contralateral eye. Three months postoperatively, corneal haze was measured with the Pentacam(R) and compared between the 2 groups. RESULTS: Statistical differences were not found in preoperative data in the tranilast or control groups (all P > 0.05). There was a strong decreasing density trend from the apex to the 3 mm radius in both groups (P 0.05). CONCLUSIONS: The use of tranilast after PRK did not inhibit corneal opacity. Additionally, Pentacam(R) can provide a useful objective measure of corneal haze.

Longitudinal measurements of luminance and chromatic contrast sensitivity: comparison between wavefront-guided LASIK and contralateral PRK for myopia / Medidas longitudinais da sensibilidade ao contraste de luminância e cromático: comparação entre wavefront-LASIK e wavefront-PRK para miopia

PURPOSE: The present study aimed to compare the postoperative contrast sensitivity functions between wavefront-guided LASIK eyes and their contralateral wavefront-guided PRK eyes. METHODS: The participants were 11 healthy subjects (mean age=32.4 ± 6.2 years) who had myopic astigmatism. The spatial contrast sensitivity functions were measured before and three times after the surgery. Psycho and a Cambridge graphic board (VSG 2/4) were used to measure luminance, red-green, and blue-yellow spatial contrast sensitivity functions (from 0.85 to 13.1 cycles/degree). Longitudinal analysis and comparison between surgeries were performed. RESULTS: There was no significant contrast sensitivity change during the one-year follow-up measurements neither for LASIK nor for PRK eyes. The comparison between procedures showed no differences at 12 months postoperative. CONCLUSIONS: The present data showed similar contrast sensitivities during one-year follow-up of wave-front guided refractive surgeries. Moreover, one year postoperative data showed no differences in the effects of either wavefront-guided LASIK or wavefront-guided PRK on the luminance and chromatic spatial contrast sensitivity functions.

OBJETIVO: A proposta do presente estudo é comparar funções de sensibilidade ao contraste obtidas após wavefront-LASIK e wavefront-PRK no olho contralateral. MÉTODOS: Os participantes foram 11 sujeitos saudáveis (idade média=32,4 ± 6,2 anos) com astigmatismo miópico. As funções de sensibilidade ao contraste espacial foram obtidas antes e três vezes após a cirurgia. O programa Psycho e uma placa gráfica da Cambridge Research Systems (VSG 2/4) permitiram gerar os estímulos com contraste espacial de luminância e cromático (verde-vermelho e azul-amarelo) de 0,85 até 13,1 ciclos/grau. Análises longitudinais e comparações entre as cirurgias foram realizadas. RESULTADOS: Não houve mudança significativa da sensibilidade ao contraste durante o primeiro ano após a cirurgia para o olho que recebeu o LASIK ou para o olho que recebeu o PRK. A comparação entre as cirurgias também foi semelhante no pós-operatório de um ano. CONCLUSÕES: Os resultados apresentados mostraram sensibilidade ao contraste semelhante durante o primeiro ano após a cirurgia refrativa com o wavefront. Além disso, no pós-operatório de um ano não houve diferença nas funções de sensibilidade ao contraste de luminância e cromático entre os olhos que receberam LASIK e os que receberam PRK.

The Effects of Laser Refractive Surgery for Correcting Residual Refractive Error after Implantation of ReSTOR(R) Multifocal IOL

PURPOSE: To evaluate the clinical effects of excimer laser refractive surgery on eyes with residual refractive error after implantation of ReSTOR(R) multifocal intraocular lenses. METHODS: We retrospectively reviewed the medical records of 10 eyes of 6 patients who had undergone cataract surgery with implantation of multifocal intraocular lenses. Photorefractive keratectomy (PRK) (5 eyes) and laser-assisted in situ keratomileusis (LASIK) (5 eyes) was performed on 10 eyes with residual refractive error. RESULTS: After cataract surgery and before laser surgery, the mean spherical equivalent (SE) was -0.34 +/- 0.89 D and the mean astigmatism was 2.08 +/- 0.55 D. Six months after laser surgery, the mean SE was -0.33 +/- 0.30 D (p = 0.354) and the mean astigmatism was 0.23 +/- 0.28 D. The changes in astigmatism between paired preoperative and postoperative values were statistically significant (p < 0.0001). At 6 months after surgery, uncorrected distance visual acuity significantly improved to 0.11 +/- 0.10 (log MAR) (p < 0.0001) There were no significant changes in the best corrected distance visual acuity and uncorrected near visual acuity (p = 0.073, p = 0.100). CONCLUSIONS: On the basis of predictability and stability, excimer laser surgery appears to be a clinically useful procedure to correct residual refractive error after implantation of ReSTOR(R) multifocal intraocular lenses.

Influences of Cylindrical Correction Amount of PRK on Accuracy of Geometric Corneal Center-Adjusted Ablation Centration

PURPOSE: To evaluate the effect of the amount of cylindrical correction on the accuracy of geometric corneal center-adjusted ablation centration selected by the surgeon in advanced surface ablation-photorefractive keratectomy (ASA-PRK). METHODS: Ninety-five myopic eyes of 62 patients who underwent ASA-PRK were divided into three groups based on the amount of myopic cylindrical correction: Group 1 or =-0.50 D and or =-1.00 D, 28 eyes. The distances and distribution of the ablation centers from the entrance pupil center were analyzed by corneal topography at one month after ASA-PRK. Risk factors for decentration (>0.3 mm) were determined from patient-related factors such as gender, age, laterality, central corneal thickness, and order of procedure and surgery-related factors such as amount of spherical correction, ablation depth, vertical scale bar percentage, and learning effect of surgeon. RESULTS: Mean decentration was 0.26 +/- 0.15 mm (0.04 to 0.83 mm). There was no statistically significant difference in the amount of decentration among the three groups (p = 0.879). Superior-nasal displacement (53.7%) of the ablation center most frequently occurred after ASA-PRK. The amount of decentration among the three groups was not dependent on either patient-related or surgery-related factors. CONCLUSIONS: ASA-PRK using the surgeon-selected ablation center with adjustment toward the geometric corneal center was found to be highly accurate in ablation centration and did not influence the amount of ablation decentration regardless of the amount of myopic cylindrical correction.

Effects of Amount of Myopic Correction on Long-term Changes in Higher-order Wavefront Aberrations in ASA-PRK

PURPOSE: To evaluate the effects of the amount of myopic correction on long-term changes in higher-order wavefront aberrations (HOAs) in advanced surface ablation-photorefractive keratectomy (ASA-PRK). METHODS: The 193 eyes of 101 patients who underwent ASA-PRK were divided into two groups according to the amount of myopic correction by the median value (Group 1 -4.37D, 96 eyes, mean -5.77 +/- 1.00D). Wavefront aberrometry was performed to measure total HOA, coma, trefoil, and spherical aberration preoperatively and at 1, 3, 6, 12, and 24 months after ASA-PRK. Statistical analysis was performed to compare changes in all HOAs between the two groups. RESULTS: Each magnitude of total HOA, coma, and spherical aberration except trefoil significantly increased at 1, 3, 6, 12, and 24 months postoperatively in each group (p -4.37D). Increases in ASA-PRK-induced HOAs primarily originated from short-term changes in the postoperative one-month period and did not return to the preoperative level during the postoperative two-year period.

Comparative Analysis of the Tear Protein Expression After Photorefractive Keratectomy Using Two-Dimensional Electrophoresis

PURPOSE:To investigate the change in the tear protein composition of patients who underwent refractive surgery. METHODS: Tear samples were collected before photorefrative keratectomy (PRK), on the first, the second, and the third postoperative day, and then a month after the operation from 40 eyes of 20 patients. These tear samples were analyzed using two-dimensional gel electrophoresis (2-DE). Matrix-associated laser desorption/ionization time of flight (MALDI-TOF) was employed for the identification of expressed proteins. Control tear samples were collected from 40 eyes of 20 healthy volunteers who had no history of ocular surgery or pathology. RESULTS: On the first postoperative day, lipocalin-1 precursor, lipocalin-1, and lysozyme were up-regulated. On the second postoperative day, serum albumin precursor and serum albumin were up-regulated. The tears collected on the third postoperative day and after 1 month had similar protein expression levels to the control group. Lipocalin 1 precursor and lysozyme were up-regulated and down-regulated after reftactive surgery, respectively. However, each protein had a different molecular weight and isopotential point. CONCLUSIONS: The tear protein composition changed uniquely in the early postoperative period, and proteins with different isopotential points were detected after PRK. We hypothesized that the healing process might influence the expression of the tear proteins.

Excimer Laser Refractive Surgery to Correct Anisometropia due to Residual Astigmatism After Cataract Surgery

PURPOSE: To evaluate the clinical effect of photorefractive keratectomy (PRK) and laser assisted in situ keratomileusis (LASIK) on eyes with anisometropia due to residual astigmatism after cataract surgery. METHODS: We retrospectively reviewed the medical records of 11 eyes of 11 patients who had undergone cataract surgery from March 2002 to November 2005. PRK (2 eyes) and LASIK (9 eyes) was performed on 11 eyes with refractive myopic or mixed astigmatism over 1.5D after cataract surgery. RESULT: Before laser surgery, the mean astigmatism was 3.23+/-1.02D and the mean spherical equivalent (SE) was -2.27+/-1.43D. Six months after laser surgery, the mean SE was 0.66+/-0.58D and the mean astigmatism was 0.73+/-0.39D. The changes in mean manifest SE and astigmatism were statistically significant between paired preoperative and postoperative values (p<0.05). At 6 months after surgery, the mean uncorrected visual acuity and best corrected visual acuity significantly improved to 0.65+/-0.17 and 0.84+/-0.11, respectively. Three eyes (27.3%) developed mild haze and were treated without sequelae. There were no other complications. CONCLUSIONS: Excimer laser surgery appears to be a clinically useful procedure to correct residual astigmatism after cataract surgery.