Changes in Corneal Dynamics and Effective Optical Zone After Transepithelial Photorefractive Keratectomy for Myopia.

Objectives: The objective of this study was to analyze the changes in the effective optical zones (EOZ) using topographic techniques on the tangential curvature difference map at post-operative 1-year following transepithelial photorefractive keratectomy (T-PRK) and to identify parameters linked to the EOZ alterations. Methods: The study comprised 55 eyes of 55 myopic patients who underwent T-PRK. EOZs were measured using the tangential curvature difference map of the Scheimpflug tomography system. Correlations between the EOZ alterations and relevant parameters were assessed. Results: The EOZ was significantly lower than the programmed optical zone (p<0.001). The decrease in the EOZ was significantly relevant to the decrease in mean keratometry (p=0.01, B/95% confidence interval [CI]: 0.139/0.033 and 0.244, standardized Beta: 0.346) and the increase in maximum keratometry (p=0.003, B/95% CI: 0.072/0.026 and 0.118, standardized Beta: 0.406). Conclusion: The EOZ decreased in the 1st year after T-PRK in eyes with myopia. The decrease in the EOZ was correlated positively with the decrease in mean and maximum keratometry. T-PRK may be an effective and safe surgery for the correction of mild-to-moderate myopia.

Advanced Surface Ablation in a Patient With Suspect Topography: A Case Report.

The purpose of this clinical report is to describe a 10-year clinical outcome of advanced surface ablation with photorefractive keratectomy (PRK) in a patient who had been previously incorrectly diagnosed with keratoconus (KC). Corneal ectasia is a rare but extremely relevant complication of laser vision correction, and KC represents a major contraindication for these procedures. Nonetheless, some surface ablation procedures, such as PRK, might be a valid option for particular patients with atypical corneal topography or subclinical or mild forms of KC. Patient education and complete preoperative refractive multimodal imaging are essential for a more conscious therapeutic decision, minimizing iatrogenic ectasia, as well as decreasing the number of patients who are incorrectly denied refractive surgery, as was the patient presented in this study.

Effect of mitomycin C on the corneal endothelial cells of Saudi patients with myopia after transepithelial photorefractive keratectomy: a two-armed cohort study.

AIM: To study the effect of mitomycin C (MMC) applied during transepithelial photorefractive keratectomy (TPRK) on the corneal endothelium one week (W1) and three months (M3) after surgery and its determinants. METHODS: In this two-armed cohort study conducted in 2022, eyes treated with MMC during TPRK (group 1) were compared with eyes not treated with MMC (group 2). The corneal endothelial cell (EC) count, EC density (ECD; cells/mm2), average (µm2), standard deviation (µm2), coefficient of variation (CV%), ECmax, ECmin, and EC percentage of hexagonality were estimated at W1 and M3. The postoperative changes in the EC count in the two groups were compared and correlated with the other independent variables. RESULTS: Group 1 had 26 eyes, and group 2 had 78 eyes. All TPRK indices were significantly higher for the eyes in group 1 than for those in group 2. The MMC usage was not a significant predictor of the change in ECD (P=0.644), change in CV (P=0.374), and change in the percentage of hexagonality of EC (P=0.164) at W1. However, the use of MMC was a significant predictor of changes in CV (P=0.014) and the change in the percentage of hexagonality of EC (P=0.039) at M3. The duration of laser exposure and the size of the optical zone influenced the correlation of MMC use with the changes in EC indices, postoperatively. CONCLUSION: The use of MMC doesn't affect ECD, CV, and percentage of hexagonality at W1 if other surgical indices are considered. At M3 after operating myopic eyes by TPRK, MMC significantly influence the CV and percentage of hexagonality. The duration of the laser application and the size of the optical zone should be considered when determining the effect of MMC on the EC indices.

Intraoperative Assessment of the Stromal Ablation in Photorefractive Keratectomy.

Purpose: To evaluate the difference between planned and measured central ablation depth (CAD) and compare the first and second operated eye in simultaneous bilateral myopic alcohol-assisted PRK. Methods: A retrospective review of patients was performed. Demographic and preoperative data was abstracted. Intraoperative assessment included environmental data, laser-planned algorithm of ablation (L-CAD), and optical coherence pachymetry (OCP) measurements. The true stromal ablation depth (O-CAD) was calculated by subtracting the immediate post-ablation OCP measurement from the OCP measurement before laser ablation. Deviation in pachymetry (DP) between O-CAD and L-CAD was also assessed. Results: The study comprised 140 eyes from 70 consecutive patients. The mean age was 26.91 ± 6.52 years, and 57.1% were females. O-CAD was significantly correlated to preoperative refractive errors and intraoperative laser settings. DP was not correlated to any of the pre- or intraoperative parameters. L-CAD showed a significant underestimation as compared to O-CAD (67.87 ± 25.42 µm and 77.05 ± 30.79 µm, respectively, p < 0.001), which was shown in 74.3% of the cases. A moderate agreement between the two methods was noted, with a mean deviation of 17%. This difference was maintained for each eye individually (p < 0.001). In addition, DP was significantly higher in the first operated eye as compared to the second operated eye (11.97 ± 16.3 µm and 6.38 ± 19.3 µm respectively, p = 0.04). Conclusion: The intraoperative assessment of stromal ablation showed significantly higher central ablation depth values compared to the laser-planned ablation algorithm. The deviation in pachymetry was higher in the first, compared to the second, operated eye. Awareness is warranted as to the discrepancy between preoperative planning and intraoperative assessment.

Refractive outcomes using Barrett formulas and patient characteristics of cataract surgery patients with and without prior LASIK/PRK.

PURPOSE: The goal of this study is to describe characteristics of cataract surgery patients who previously underwent laser in situ keratomileusis/photorefractive keratectomy (LASIK/PRK) in comparison to non-LASIK/PRK cataract surgery patients including psychiatric comorbidities, as well as describe refractive prediction error after cataract surgery while accounting for axial length (AL) using the Barrett True-K and Barrett Universal II formulas. METHODS: This was a retrospective study of patients from the University of Colorado Cataract Outcomes Registry. The primary outcomes were refraction prediction error (RPE), mean absolute RPE, and median absolute RPE. Outcomes were stratified by five axial length groups. Univariate and multivariate models for RPE were stratified by the AL group. RESULTS: Two hundred eighty-one eyes with prior LASIK/PRK and 3101 eyes without are included in the study. Patients with prior LASIK/PRK were significantly younger: 67.0 vs 69.9 years, p < 0.0001. The LASIK/PRK group had significantly better mean pre-operative BCVA in comparison to the non-LASIK group, logMAR 0.204 vs logMAR 0.288, p = 0.003. The LASIK/PRK group had significantly lower rates of cardiovascular disease (18.5% vs 29.3%, p < 0.001), hypertension (49.1% vs 59.3%, p < 0.012), and type 2 diabetes (10.7% vs 26.0%, p < 0.001), and no significant difference in psychiatric disease. The absolute RPE was higher for the LASIK group for all ALs, but only significantly higher for eyes with AL less than 25 mm. CONCLUSION: Patient eyes with prior LASIK/PRK surgery undergoing cataract surgery were significantly younger, had significantly less comorbidities, and a significantly better pre-operative BCVA. Using the Barrett formulas, absolute prediction error for eyes with longer ALs was not significantly worse for LASIK/PRK eyes than those without and the difference was smaller for eyes with longer AL.

Does the introduction of streamlight decrease refractive surgery operating time?

PURPOSE: The aim of the study was to analyze the time-savings associated with introduction of Streamlight™ (Alcon Laboratories, Fort Worth, TX, USA) transepithelial photorefractive keratectomy (PRK) in surface corneal ablations. METHODS: All refractive surgeries were performed using the Alcon WaveLight® EX500 at the ArtLife Clinic, Gdansk, Poland. The study included patients treated for refractive errors with transepithelial PRK between April 2019 and October 2021, who were matched with patients treated with alcohol-assisted PRK during the same period. Only results for the left eye were analyzed. RESULTS: One-hundred-five patients underwent transepithelial PRK (age 33.42 ± 8.67 years) and were matched with 105 patients that underwent alcohol-assisted PRK (age 33.05 ± 10.16 years; p = 0.11). The mean preoperative spherical equivalent refraction was - 2.04 ± 2.28 D, and - 1.9 ± 1.71 D for the transepithelial and alcohol-assisted PRK group, respectively (p = 0.20). The total surgery time was non-significantly shorter in transepithelial PRK (349.46 ± 47.83 s) than in alcohol-assisted PRK (354.93 ± 137.63 s; p = 0.7); however, the variance of surgical time was significantly lower in transepithelial PRK (p < 0.001). The laser treatment duration was greater in transepithelial PRK (41.78 ± 17.2 s) than in alcohol-assisted PRK (8.48 ± 6.12 s; p < 0.001), and so was the number of breaks during the laser treatment (0.95 ± 0.63 vs. 0.53 ± 0.88, respectively; p < 0.001). CONCLUSION: The introduction of transepithelial PRK did not bring significant time-associated savings into the refractive surgery suite.

Implication of Corneal Refractive Surgery in Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked disorder due to a dystrophin mutation and is the leading cause of muscular dystrophy. DMD presents with characteristic systemic effects, including severe muscular atrophy, cardiomyopathy, and ocular manifestations. Performing corneal refractive surgeries in patients with DMD raises concerns regarding patient positioning, risk of cataracts, and other comorbid conditions. Published reports of photorefractive keratectomy, laser-assisted in situ keratomileuses, and small incision lenticule extraction are lacking in this population. Here, we discuss a patient being evaluated for a corneal refractive surgery. This article also discusses the current understanding of DMD, known ocular manifestations, and factors to consider when evaluating a patient for potential corrective vision laser surgery.

Two-phase mechanism in the treatment of corneal stromal fibrosis with topical losartan.

Recent studies in rabbits and case reports in humans have demonstrated the efficacy of topical losartan in the treatment of corneal scarring fibrosis after a wide range of injuries, including chemical burns, infections, surgical complications, and some diseases. It is hypothesized that the effect of losartan on the fibrotic corneal stroma occurs through a two-phase process in which losartan first triggers the elimination of myofibroblasts by directing their apoptosis via inhibition of extracellular signal-regulated kinase (ERK)-mediated signal transduction, and possibly through signaling effects on the viability and development of corneal fibroblast and fibrocyte myofibroblast precursor cells. This first step likely occurs within a week or two in most corneas with fibrosis treated with topical losartan, but the medication must be continued for much longer until the epithelial basement membrane (EBM) is fully regenerated or new myofibroblasts will develop from precursor cells. Once the myofibroblasts are eliminated from the fibrotic stroma, corneal fibroblasts can migrate into the fibrotic tissue and reabsorb/reorganize the disordered extracellular matrix (ECM) previously produced by the myofibroblasts. This second stage is longer and more variable in different eyes of rabbits and humans, and accounts for most of the variability in the time it takes for the stromal opacity to be markedly reduced by topical losartan treatment. Eventually, keratocytes reemerge in the previously fibrotic stromal tissue to fine-tune the collagens and other ECM components and maintain the normal structure of the corneal stroma. The efficacy of losartan in the prevention and treatment of corneal fibrosis suggests that it acts as a surrogate for the EBM, by suppressing TGF beta-directed scarring of the wounded corneal stroma, until control over TGF beta action is re-established by a healed EBM, while also supporting regeneration of the EBM by allowing corneal fibroblasts to occupy the subepithelial stroma in the place of myofibroblasts.

Transepithelial Photorefractive Keratectomy-Review.

The type and nature of refractive surgery procedures has greatly increased over the past few decades, allowing for almost all patient populations to be treated to extremely high satisfaction. Conventional photorefractive keratectomy involves the removal of the corneal epithelium through mechanical debridement or dilute alcohol instillation. An improvement to this method utilises laser epithelial removal in a single-step process termed transepithelial photorefractive keratectomy (transPRK). We explore the history of transPRK from its early adoption as a two-step process, identify different transPRK platforms from major manufacturers, and describe the role of transPRK in the refractive surgery armamentarium. This is a narrative review of the literature. This review finds that TransPRK is a safe and effective procedure that works across a variety of patient populations. Though often not seen as a primary treatment option when compared to other corneal-based procedures that offer a faster and more comfortable recovery, there are many scenarios in which these procedures are not possible. These include, but are not limited to, cases of corneal instability, previous refractive surgery, or transplant where higher-order aberrations can impair vision in a manner not amenable to spectacle or contact lens correction. We discuss refinements to the procedure that would help improve outcomes, including optimising patient discomfort after surgery as well as reducing corneal haze and refractive regression.

Clinical Evaluation of Corneal Endothelial Parameters following Laser Refractive Surgery in Myopic Eyes: A Review.

Background: The aim of this review was to investigate the influence of various laser refractive surgery methods on the corneal endothelium in myopic patients. The role of the corneal endothelium in laser refractive surgery (LRS) is currently being addressed in the assessment of postoperative corneal edema risk. Methods: Changes in corneal endothelial cell density and morphology after LRS were evaluated based on a systematic review of current studies. The results of a literature search in the PubMed, Science Direct, Google Scholar, and the Web of Science databases, as well as a manual search, were selected for the final review according to the PRISMA 2020 flow diagram. Results: We included 24 prospective clinical trials in the review: surface ablation (twelve), LASIK and FemtoLASIK (two), femtosecond lenticule extraction (two), and comparable studies (eight). Endothelial cell density was determined by specular or in vivo confocal microscopy. In most studies, no statistically significant differences were found between preoperative and postoperative endothelial parameters. In nine studies, the changes were statistically significant, but no vision-threatening complications occurred, and no serious corneal complications developed in any eyes during the follow-up period. Conclusions: Based on collected data, laser keratorefractive surgery appears not to exert a significant effect on the corneal endothelium.

Headache Attributed to Refractive Error: Improvement after Topography-Guided Photorefractive Keratectomy with Corneal Cross-Linking in Patients with Keratoconus.

PURPOSE: To investigate if topography-guided photorefractive keratectomy (TGPRK) alleviates headache, particularly headache attributed to refractive errors (HARE) in keratoconus. METHODS: Patients diagnosed with keratoconus undergoing TGPRK for refractive correction were included. Best spectacle corrected visual acuity (BSCVA) using the logMAR scale and refractive error were measured. Patients answered a questionnaire exploring headaches, characteristics, treatment, and the Headache Impact Test (HIT-6) before and 6 months after the surgery. RESULTS: 40 patients were included. Preoperatively, 24 patients (60%) met criteria for headaches: five for migraine, 14 for HARE, and five for tension-type headache (TTH). Patients with headaches preoperatively were more likely to require bilateral TGPRK, and the mean sphere and cylindrical power were higher. Postoperatively, 15 out of the 24 patients of the headache group experienced complete resolution of headaches, and only nine patients met diagnostic criteria for headaches: two for migraine, six for HARE, and one for TTH. The number of headaches reduced from 4.4 ± 2.4 to 0.5 ± 0.7 days/week (p < 0.001). Headache duration decreased from 108.5 ± 100.7 min to 34.4 ± 63.5 min (p = 0.002). Postoperatively, the consumption of analgesia decreased. The HIT-6 revealed an improvement in the quality-of-life post-procedure (p < 0.001). CONCLUSIONS: Surgical correction of irregular astigmatism in patients with keratoconus can alleviate or resolve headaches in a large proportion of patients, resulting in an improvement in their quality of life. Physicians should consider keratoconus in patients fitting criteria for HARE not alleviated by spectacle correction and suboptimal vision in glasses.

Refractive results of photorefractive keratectomy comparing trans-PRK and PTK-PRK for correction of myopia and myopic astigmatism.

PURPOSE: To compare refractive outcomes after transepithelial photorefractive keratectomy (tPRK) and combined phototherapeutic keratectomy (PTK-PRK) procedure using two different excimer laser platforms for correction of myopia and myopic astigmatism. METHODS: In this retrospective multicenter study, we compared the results of two different PRK methods. The first group received a tPRK treatment with the Amaris750 excimer laser (Schwind eye-tech solutions). The second group received a combined PTK-PRK treatment with the MEL90 excimer laser (Carl Zeiss). Only healthy eyes with no previous surgery and a spherical equivalent (SE) of -1 to -8 diopters (D) were included. Preoperative spherical equivalent (SE), age, and sex were matched among the two groups. All treatments were performed by the same surgeon in different clinics. This study was approved by the local Ethics Committee (No. 2022-1980). RESULTS: We included 154 eyes of 86 patients in our study. There was no difference in predictability of SE between the two groups. Efficacy and safety indices were equally high in both groups. Similarly, no significant differences were seen in change of higher order aberrations (HOA) between the two groups (p > 0.05). No complications occurred. CONCLUSION: Both investigated methods provide safe and effective refractive results. The combination of PTK with PRK may be a suitable option to the already used one-step tPRK for the correction of myopia.

Corneal stromal localization of TGF beta isoforms in spontaneous persistent epithelial defects after PRK in rabbits.

The purpose of this study was to evaluate transforming growth factor beta (TGFß) isoform localization in rabbit corneas with spontaneous persistent epithelial defects (PEDs) after photorefractive keratectomy (PRK). Four cryofixed corneas from a previously reported series of PEDs in rabbits that had PRK were evaluated with triplex immunohistochemistry (IHC) for TGFß3, myofibroblast marker alpha-smooth muscle actin (α-SMA) and mesenchymal marker vimentin. One cornea had sufficient remaining tissue for triplex IHC for TGFß1, TGFß2, or TGFß3 (each with α-SMA and vimentin) using isoform-specific antibodies. All three TGFß isoforms were detected in the subepithelial stroma at and surrounding the PED. Some of each TGFß isoform co-localized with α-SMA of myofibroblasts, which could be TGFß isoform autocrine production by myofibroblasts or TGFß-1, -2, and -3 binding to these myofibroblasts.

Late-Onset Haze and Severe Corneal Flattening after Combined Corneal Collagen Cross-Linking and Photorefractive Keratectomy (CXL Plus): A Case Report.

Introduction: Significant corneal flattening and haze are important complications that can occur after combined corneal collagen cross-linking (CXL) and photorefractive keratectomy (PRK) procedures (CXL Plus). Case Presentation: We present a 24-year-old man who underwent combined standard CXL and PRK. The patient experienced satisfactory vision for approximately 4 years after the surgery. However, after this period, he began to complain of visual blurring. Subsequent examination revealed significant corneal haze, excessive flattening in both eyes, and thinning (thinnest point 227 µm in the right eye, 244 µm in the left eye) 4 years postoperatively. Upon presentation, the corrected distance visual acuity (CDVA) was 20/200 in the right eye and 20/400 in the left eye. The presenting refraction was +2.50 sph, -3.50 cyl *114 in the right eye and +11.5 sph, -9.75 cyl *81 in the left eye. With rigid gas permeable contact lenses, the corrected visual acuity was 20/50 in both eyes. Before the CXL Plus surgery, initial refraction and CDVA were 20/50 in the right eye (-5.50 sph, -3.00 cyl *175) and 20/30 in the left eye (-5.50 sph, -2.75 cyl *175). The patient was treated by penetrating keratoplasty. The CDVA reached 20/30 at the final follow-up. Conclusion: Our report highlights significant corneal haze and flattening that occurred 4 years after combined CXL and PRK treatment. These findings suggest that this procedure might not be safe in suspected patients of keratoconus. Further long-term follow-up research is necessary to evaluate the safety of combined CXL and PRK procedures.

Investigation of corneal epithelial thickness and irregularity by optical coherence tomography after transepithelial photorefractive keratectomy.

CLINICAL RELEVANCE: Corneal epithelial healing after refractive surgery is a clinically significant issue, especially for surface ablation procedures, and this can be monitored using optical coherence tomography (OCT). BACKGROUND: The aim of this work is to investigate the corneal epithelial thickness and irregularity by OCT after transepithelial photorefractive keratectomy (t-PRK) and analyse its correlation with visual and refractive outcomes. METHODS: Patients aged ≥18 years with myopia, with or without astigmatism, who underwent t-PRK between May 2020 and August 2021 were included. All participants were subjected to complete ophthalmic examinations and OCT pachymetry at every follow-up visit. Patients were followed up at 1 week and 1, 3, and 6 months postoperatively. RESULTS: A total of 67 patients (126 eyes) were enrolled in this study. One month postoperatively, spherical equivalent refraction and visual acuity achieved preliminary stability. However, central corneal epithelial thickness (CCET) and standard deviation of the corneal epithelial thickness (SDcet) took 3-6 months to progressive recovery. Patients with higher baseline spherical equivalent refraction were associated with slower epithelial recovery. At every follow-up time point, a significant superior-inferior difference in the minimum corneal epithelial thickness area was observed. Higher stromal haze was correlated with higher spherical equivalent refraction (both baseline and residual) but had no relation with visual outcomes. There was a significant correlation between higher CCET with a better uncorrected distance visual acuity and lower corneal epithelial thickness irregularity. CONCLUSIONS: CCET and SDcet measured by OCT seem to be a good auxiliary indicator for reflecting the status of corneal wound recovery after t-PRK surgery. However, a well-designed randomised control study is needed to confirm the study results.

Refractive surgical correction and treatment of keratoconus.

Keratoconus is an ectatic corneal disorder that causes severe vision loss. Surgical options allow us to correct, partially or totally, the induced refractive error. Intracorneal ring segments (ICRS) implantation represents a minimally invasive surgical option that improves visual acuity, with a high success rate and a low overall complication rate. Corneal allogenic ICRS consists of ring segments derived from allogenic eye bank-processed donor corneas. Selective topography-guided transepithelial photorefractive or phototherapeutic keratectomy combined with CXL is another way in selected cases to improve spectacles corrected distance visual acuity. The microphotoablative remodeling of the central corneal profile is generally planned by optimizing the optical zones and minimizing tissue consumption. Phakic intraocular lens (PIOL) implant is considered in patients with stable disease and acceptable anatomical requirements. The two types of pIOLs, depending on their implantation inside the eye, are anterior chamber-pIOLs, which fixate to the anterior surface of the iris by using a polymethomethacrolate claw at the two haptics, and posterior chamber-pIOLs. In patients with both cataracts and keratoconus, the correct IOL power is difficult to obtain due to the irregular corneal shape and K values. Toric IOL is recommended, but carefully judging the topography and the possible need of subsequent keratoplasties.

The association of pre-photorefractive keratectomy Schirmer-1 test value with postoperative corneal epithelial thickness, ocular surface discomfort, and visual acuity

ABSTRACT Purpose: To investigate the association of pre--photorefractive keratectomy Schirmer-1 test value with post--photorefractive keratectomy central corneal epithelial thickness, ocular surface disease index score, and uncorrected distance visual acuity. Methods: Patients were categorized according to preoperative Schirmer-1 value: the normal Schirmer Group (n=54; Schirmer-1 test value, >10 mm) and the low Schirmer Group (n=52; Schirmer-1 test value, between 6 and 10 mm). We analyzed ablation depth, visual acuity, result of Schirmer-1 test (with anesthesia), tear film break-up time, ocular surface disease index score, central corneal epithelial thickness, and spherical equivalent refraction. Results: We found significant differences between the groups in Schirmer-1 test value, tear film break-up time, and ocular surface disease index score, both preoperatively and postoperatively (p<0.001). The preoperative central corneal epithelial thicknesses of the two groups were similar (p>0.05). After photorefractive keratectomy, the Schirmer-1 test value and spherical equivalent refraction decreased in both groups (p<0.05), and ocular surface disease index scores and central corneal epithelial thickness values increased in the low Schirmer Group (p<0.001) but not in the normal Schirmer Group (p>0.05). The postoperative central corneal epithelial thicknesses of the low Schirmer Group were significantly higher than those of the normal Schirmer Group (p<0.001). Postoperative uncorrected distance visual acuity did not differ significantly between the two groups (p>0.05). Conclusions: In patients with low Schirmer-1 test values before photorefractive keratectomy, the corneal epithelium thickened and ocular surface complaints increased during the postoperative period. However, changes in the corneal epithelium did not affect the postoperative uncorrected distance visual acuity. To reduce postoperative problems on the ocular surface in these patients, we recommend that dry eye be treated before photorefractive keratectomy.

Corneal ectasia following photorefractive keratectomy: a confocal microscopic case report and literature review / Ectasia corneana após ceratectomia fotorrefrativa: relato de caso de microscopia confocal e revisão da literatura

ABSTRACT The occurrence of corneal ectasia after photorefractive keratectomy is a rare but serious complication of refractive surgery. Possible risk factors are not well assessed, but a probable reason is the failure to detect keratoconus preoperatively. In this report, we describe a case of corneal ectasia after photorefractive keratectomy in a patient who presented a suspicious tomography pattern preoperatively but had no degenerative alterations associated with pathologic keratoconus, as revealed by in vivo corneal confocal microscopy. We also review eligible case reports of post-photorefractive keratectomy ectasia to find similar characteristics.

RESUMO A ocorrência de ectasia corneana após ceratectomia fotorrefrativa é uma complicação rara, porém grave, em cirurgia refrativa. Os possíveis fatores de risco não são bem avaliados, mas a opinião atual é que a falha na detecção de ceratocone pré-operatório possa ser o principal motivo. Neste relato, descrevemos um caso de ectasia corneana após ceratectomia fotorrefrativa em paciente apresentando padrão tomográfico suspeito no pré-operatório, mas sem alterações degenerativas associadas a ceratocone patológico, conforme revelado por microscopia confocal in vivo da córnea. Além disso, revisamos, na literatura, relatos de casos elegíveis de ectasia pós-ceratectomia fotorrefrativa para encontrar características semelhantes.

Effect of small incision lenticule extraction on the treatment of myopia patients and the impact on corneal biomechanics / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To investigate the effect of small incision lenticule extraction(SMILE)on the treatment of myopia patients, and the impact on corneal biomechanics.METHODS:Retrospective study. A total of 120 myopic patients(240 eyes)who were scheduled to undergo corneal refractive surgery in Anyang Eye Hospital from January 2020 to December 2021 were selected. The patients were divided into SMILE group(64 patients, 128 eyes)and transepithelial photorefractive keratectomy(TransPRK)group(56 patients, 112 eyes)according to the surgical treatment method. The two groups were compared in terms of uncorrected visual acuity, corneal biomechanics, corneal endothelial cell count, posterior corneal surface height and corneal surface regularity index at 1, 7 d, 1, 3, 6 mo and 1 a after surgery, and surgical complications.RESULTS:The uncorrected visual acuity of the SMILE group at 1, 7 d and 1 mo after surgery was better than that of the TransPRK group(all P&#x003C;0.001), but there was no statistically significant difference between the groups at 3, 6 mo and 1 a after surgery(all P&#x003E;0.05). Compared with preoperative values, corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in both groups showed a first decreasing and then increasing trend after surgery. The corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in the SMILE group at 1, 7 d and 1 mo after surgery were higher than those in the TransPRK group(all P&#x003C;0.05), but there was no statistically significant difference between the groups at 3, 6 mo and 1 a after surgery(all P&#x003E;0.05). There were no significant changes of corneal endothelial cell count and corneal posterior surface height in the two groups after surgery(all P&#x003E;0.05). Furthermore, corneal surface regularity index of the two groups showed a first increasing and then decreasing trend after surgery, with no statistically significant difference between the groups(P&#x003E;0.05), and there was no statistically significant difference in the incidence of postoperative complications between the groups(P&#x003E;0.05).CONCLUSION:Compared with TransPRK, SMILE has less influence on corneal biomechanics, and better visual recovery in the early stage. There is no difference in long-term visual acuity between the two surgeries, and both have good safety and effectiveness.

A sequential approach to the management of an advanced case of pellucid marginal degeneration.

Purpose: We report a sequential approach in the management of a case with advanced pellucid marginal degeneration (PMD). The management was tailored based on the patient's corneal topography and degree of corneal astigmatism. Full thickness corneal transplants in cases of PMD carry a prolonged rehabilitation period and the risk of graft failure.This case consisted of lamellar wedge resection followed by wavefront guided transepithelial photorefractive keratectomy (wTPRK) combined with accelerated corneal crosslinking (aCXL) in preparation for a cataract extraction with intraocular lens. Observation: A 68-year-old gentleman with advanced PMD underwent phacoemulsification with toric intraocular lens (T-IOL) for the right eye and a lamellar wedge resection, followed by wTPRK combined with aCXL for the contralateral eye. The left eye underwent a sequential approach to regularize the cornea, minimize the higher order aberrations (HoA) and degree of corneal astigmatism. Effective visual rehabilitation was achieved with significant visual improvement. Conclusion and importance: Although advanced PMD may have limited options for visual rehabilitation, a sequential stepwise approach may be considered in such cases, permitting a better quality with less invasive options.