Corneal Refractive Procedures Research Articles

Photorefractive Keratectomy: Technical Evolution, Refractive Outcomes, Corneal Wound Healing Response, and Complications.

Photorefractive keratectomy (PRK) was the first excimer laser procedure developed to treat refractive errors. The safety and efficacy of PRK established it as one of the most performed corneal refractive procedures worldwide. With the introduction of laser in situ keratomileusis (LASIK), and more recently keratorefractive lenticule extraction (KLEx) procedures, many corneal surgeons favor these newer corneal procedures as the first choice due to faster visual rehabilitation and less discomfort during the early postoperative period. Importantly, however, PRK remains a viable alternative for most corneal refractive candidates and there are many situations in which PRK remains the refractive procedure of choice. This review addresses the technical evolution of PRK-mechanical epithelial debridement versus alcohol-assisted epithelial removal versus excimer laser-assisted epithelial debridement (transepithelial) PRK-and reports the PRK refractive outcomes compared to other keratorefractive laser procedures. The corneal wound response associated with each PRK technique and the indications, limitations, and complications of PRK are reviewed to aid refractive surgeons to best position PRK in their overall practice. [J Refract Surg. 2024;40(10):e754-e767.].

Retrospective Study Comparing Topography-Guided and Wavefront-Optimized LASIK Procedures in a Single Center.

To compare visual outcomes of eyes that had laser refractive surgery with the Contoura Phorcides treatment plan and eyes that had laser refractive surgery with the wavefront-optimized treatment plan using the same laser. Retrospective chart review of clinical outcomes of eyes that had either Contoura with Phorcides (CP) or wavefront-optimized (WFO) corneal refractive procedures using the Wavelight EX500 (Alcon Vision, LLC). Data were collected and compared for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, change in postoperative UDVA compared to preoperative CDVA, and change in postoperative CDVA compared to preoperative CDVA. Total eyes included were 348, with 227 in the CP Group and 121 in the WFO Group. Post-operatively, there was a significantly higher percentage of eyes in the CP Group that were 20/16 or better compared to the WFO Group (57%, 129 eyes, and 17%, 21 eyes, respectively; p < 0.001). The percentage of eyes that gained 1 or more Snellen lines of UDVA compared to preoperative CDVA was higher in the CP Group (47%; 107 eyes) compared to the WFO Group (12%; 14 eyes), which was statistically significant (p < 0.001). Differences in refraction were statistically significant. Topography-guided and wavefront-optimized treatment profiles both provided excellent refractive results. A higher percentage of eyes that were treated using Contoura with Phorcides achieved 20/16 or better unaided distance vision compared to eyes receiving a wavefront-optimized treatment plan.

BCLA CLEAR Presbyopia: Management with corneal techniques

Corneal techniques for enhancing near and intermediate vision to correct presbyopia include surgical and contact lens treatment modalities. Broad approaches used independently or in combination include correcting one eye for distant and the other for near or intermediate vision, (termed monovision or mini-monovision depending on the degree of anisometropia) and/or extending the eye’s depth of focus [1]. This report reviews the evidence for the treatment profile, safety, and efficacy of the current range of corneal techniques for managing presbyopia.The visual needs and expectations of the patient, their ocular characteristics, and prior history of surgery are critical considerations for patient selection and preoperative evaluation. Contraindications to refractive surgery include unstable refraction, corneal abnormalities, inadequate corneal thickness for the proposed ablation depth, ocular and systemic co-morbidities, uncontrolled mental health issues and unrealistic patient expectations.Laser refractive options for monovision include surface/stromal ablation techniques and keratorefractive lenticule extraction. Alteration of spherical aberration and multifocal ablation profiles are the primary means for increasing ocular depth of focus, using surface and non-surface laser refractive techniques. Corneal inlays use either small aperture optics to increase depth of field or modify the anterior corneal curvature to induce corneal multifocality. In presbyopia correction by conductive keratoplasty, radiofrequency energy is applied to the mid-peripheral corneal stroma, leading to mid-peripheral corneal shrinkage and central corneal steepening. Hyperopic orthokeratology lens fitting can induce spherical aberration and correct some level of presbyopia.Postoperative management, and consideration of potential complications, varies according to technique applied and the time to restore corneal stability, but a minimum of 3 months of follow-up is recommended after corneal refractive procedures. Ongoing follow-up is important in orthokeratology and longer-term follow-up may be required in the event of late complications following corneal inlay surgery.

Post-refractive Surgery Dry Eye: A Systematic Review Exploring Pathophysiology, Risk Factors, and Novel Management Strategies.

Dry eye disease frequently manifests following corneal refractive procedures, significantly impacting patients' quality of life. This review systematically synthesizes current evidence on the pathophysiological mechanisms, risk factors, and therapeutic interventions for post-refractive surgery dry eye. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, a systematic review of literature published until August 2023 was conducted, focusing on post-refractive surgery dry eye. Eighteen relevant studies were identified through screening and eligibility assessment. A qualitative synthesis of outcomes was performed using narrative and thematic analysis methods. Surgically induced neurotrophic deficiency, stemming from nerve transection, triggers a cascade of events including apoptosis, inflammation, and lacrimal dysfunction, ultimately leading to tear film instability. Risk factors such as female gender, thyroid eye disease, meibomian gland dysfunction, higher ablation depths, and the use of LASIK over surface ablation exacerbate the condition. While conventional treatments like artificial tears provide temporary relief, emerging interventions such as nerve growth factors, matrix metalloproteinase inhibitors, serum eye drops, and specialized contact lenses show promise in promoting nerve regeneration and epithelial healing. Strategies such as customized ablation profiles, smaller optical zones, and nerve-sparing techniques like small incision lenticule extraction demonstrate potential advantages. A multifaceted therapeutic approach targeting neuroprotection, anti-inflammatory mechanisms, and tear film stabilization is imperative for effectively managing post-refractive surgery dry eye. Future research should focus on evaluating prognostic biomarkers, exploring precision medicine approaches, and investigating neuroprotective adjuvants to further enhance treatment outcomes.

Reasons for declining corneal refractive laser correction for refractive candidates in Southern India.

To analyze the reasons for declining corneal refractive laser correction procedures in patients presenting to tertiary eye care centers in Tamil Nadu, Southern India, and review the literature. Retrospective case records of subjects presenting from January 2019 to December 2021 for refractive surgery workup were analyzed. Demographic details and refractive parameters of patients rejected for corneal refractive laser corrections (CRLC) were documented and reviewed. A total of 2358 patients presented for refractive surgery evaluation during the study period, and out of them, 395 patients (16.8%) were not considered ideal candidates for undergoing CRLC. The common reasons for rejecting the patients were unfit topography (n = 110, 27.8%), unstable refraction over a one-year duration (n = 9, 2.27%), low corneal thickness (n = 85, 21.5%), keratoconus (n = 5, 12.9%), and other ocular and systemic disorders (n = 48, 12.1%). There was a marked change in magnitude and rationalization for not performing either laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy in our study. The reasons are unfit topography, keratoconus, and systemic disorders, which were diagnosed during pre-LASIK screening workup, being the most common cause for rejecting patients for corneal refractive corrections.

Influence of Preoperative Parameters on the Ratio of Keratometric Change per Diopter of Attempted Spherical Equivalent (∆K/∆SEQ) for Myopic Correction Within LASIK, PRK, and SMILE.

To compare 3 of the most common corneal refractive procedures; PRK, LASIK, and SMILE assessing ΔK/ΔSEQ ratio and its correlation with preoperative demographics including age, keratometry, pachymetry, cylinder value, and attempted myopic correction. The goal was to analyze the relative strength of each preoperative parameter in accounting for changes in ∆K/∆SEQ. A total of 370 eyes from 102 male and 97 female patients (173 eyes PRK, 153 LASIK, and 44 SMILE) with ages ranging from 20 to 51 underwent refractive surgery for myopia between -0.25 and -7.71 D manifest refraction spherical equivalent (MRSE). All surgeries were performed at a single surgery center in Draper, Utah. The Pentacam was used for all optical measurements and data were gathered pre-operatively and then again 1-year post-operatively. Only patients who achieved emmetropia at a visual acuity of 20/25 or better were included. The mean ΔK/ΔSEQ ratio for LASIK (0.839 ± 0.020) was significantly greater than that of PRK (0.775 ± 0.022) and SMILE (0.709 ± 0.046). Age was found to negatively correlate with ΔK/ΔSEQ for both LASIK (r = -0.177) and SMILE (r = -0.451) procedures. Pre-op keratometry was found to negatively correlate with ΔK/ΔSEQ for LASIK (r = -0.202) but not for PRK or SMILE. Pre-op pachymetry was not correlated with ΔK/ΔSEQ for any of the procedures. Attempted myopic spherical equivalent (SEQ) correction was positively correlated with ΔK/ΔSEQ for LASIK (r = 0.236), PRK (r = 0.459), and SMILE (r = 0.304). Lastly, pre-op cylinder value was found to be correlated to ΔK/ΔSEQ in SMILE (r = -0.367), but not in LASIK or PRK. The ΔK/ΔSEQ ratio not only differs depending on the procedure being done but also by pre-operative factors such as age, keratometry, attempted correction, and cylinder value. Multiple linear regression analysis revealed that the attempted correction had the greatest effect on ∆K/∆SEQ out of all parameters in LASIK and PRK. For SMILE, age had the greatest predictive value of the change in ∆K/∆SEQ. While the exact effect of these parameters will vary by surgeon, all of these should be factored into a refractive surgeon's nomograms in order to achieve optimal visual outcomes for their patients.

Comparison of Central Corneal Thickness Measurement by Specular Microscopy, Optical Coherence Tomography, Optical Biometry and Ultrasound Pachymetry in Normal Eyes

BACKGROUND&#x0D; Precise central corneal thickness (CCT) measurement is of utmost importance in various corneal diseases and refractive procedures. Various methods are available to measure CCT. But studies comparing CCT measurements with different devices have shown variable results. This study compares the CCT measurements by different devices and Ultrasound Pachymetry (USP).&#x0D; METHODS&#x0D; This prospective study that was conducted from October 2017 to June 2019 included 100 subjects aged more than 18 years and CCT was measured by non-contact specular microscopy (NCSM), spectral domain optical coherence tomography (SD-OCT), optical biometry (OB) and USP in normal eyes. For every patient and with each device, three readings were taken and an average was recorded. The data recorded per protocol was analyzed using Intraclass correlation coefficient and Bland-Altman analysis.&#x0D; RESULTS&#x0D; The mean value of CCT with NCSM, SD-OCT, OB, USP was 528.98±32.18µm, 532.64±30.49µm, 517.47±31.89µm and 533.39±33.44µm, respectively. The intraclass correlation was found to be maximum between NCSM and USP (0.953, p&lt;0.001). The mean paired difference of CCT values with SD-OCT and USP was statistically insignificant (-0.75±14.73, p=1.00) whereas the difference obtained with all other devices was statistically significant.&#x0D; CONCLUSIONS&#x0D; A statistically significant positive correlation (p&lt;0.001) was observed on comparing all the four devices with each other for measurement of CCT. The OCT had the best agreement and also positively correlated with USP. Hence, we conclude that OCT can be an effective alternative to USP for measuring CCT.

Implantable phakic contact lens exchange after seven years

Implantable phakic contact lens (IPCL) exchange or removal is commonly done in case of wrong size implantation leading to either pupillary block glaucoma or cataract, residual refractive error, recurrent uveitis, and endothelial cell loss. Usual time for phakic lens exchange is within 3–6 months after the primary procedure. In this case report, we have shown that IPCL exchange can be considered as an option even after a long period of 7 years in young, high myopic patients, where clear lens extraction and corneal refractive procedure are not recommended.

Use of corneal cross-linking beyond keratoconus: a systemic literature review.

The success of corneal collagen cross-linking in altering keratoconus' clinical course has driven a search for further uses of this procedure. This literature review aims to analyze the scientific evidence available for the benefit of cross-linking in the management of ophthalmic diseases other than progressive keratoconus or ectasia induced by corneal refractive procedures. A systemic literature review. We reviewed 97 studies. We found that collagen cross-linking can limit the progression of several other corneal ectasias, thus reducing and limiting the need for keratoplasty. Collagen cross-linking also can reduce the refractive power of the cornea and can be considered for a moderate degree of bacterial keratitis or when the organism is unidentified, which is refractive to antibiotics alone. However, the comparative rarity of these procedures has limited the extent of evidence. In fungal, Acanthamoeba, and herpes virus keratitis, the evidence is inconclusive of the safety and efficacy of cross-linking. Current clinical data is limited, and laboratory data has not fully correlated with published clinical data.

Goldmann and modified Goldmann tonometry measuring intraocular pressure changes in eyes which underwent myopic laser in situ Keratomileusis and photorefractive keratectomy

PurposeCompare intraocular pressure (IOP) measured by a standard Goldmann applanation tonometer prism (IOPg) and a modified correcting applanation tonometer surface Goldmann prism (IOPc) before and after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).MethodsGoldmann tonometry was analyzed in a retrospective, cross-sectional study, using both GAT and modified-GAT prisms pre-operatively and at the 3 month post-operative appointment on 120 eyes (64 patients) who received LASIK (n = 58) or PRK (n = 62). Demographics, central corneal thickness (CCT), manifest refraction and corneal curvature (CC) data was collected at each visit as well as surgical parameters, including maximum ablation depth.ResultsMean paired IOP following LASIK decreased by − 3.28 ± 3.2 mmHg measured by IOPg and − 1.93 ± 3.3 mmHg by IOPc (p ≤ 0.0001). Mean paired IOP following PRK reduced by − 1.92 ± 3.6 mmHg measured by IOPg and − 1.06 ± 3.6 mmHg by IOPc (p ≤ 0.0001). Increased LASIK ablation depth and post-procedural change in CCT trended toward a statistically significant reduction in IOPg (p = 0.07,p = 0.12), but not IOPc (p = 0.18,p = 0.32). PRK ablation depth was not associated with a reduction in IOPg or IOPc.DiscussionThe modified Goldmann (IOPc) prism measured less of an IOP reduction following LASIK and PRK compared to the standard (IOPg) prism, and the IOP reduction with both prisms was associated with the degree of myopic correction.What is already known and the residual queryCorneal refractive surgery generally demonstrates significant postoperative Goldmann IOP reductions. Presumably, this is due to corneal biomechanical changes for which a newer method of Goldmann IOP measurement may be able to compensate.What this study addsA modified, corneal conforming Goldmann prism demonstrates significantly less IOP reduction following myopic LASIK and PRK compared to the standard flat Goldmann prism.How this study might affect research, practice or policyA newer, modified Goldmann prism may help detect glaucoma and OHT at an earlier stage in patients which have undergone LASIK or PRK. The findings corroborate predicted corneal biomechanical changes following the most common corneal refractive procedures.

Central Toxic Keratopathy after Small Incision Lenticule Extraction.

Small incision lenticule extraction (SMILE) is a corneal refractive surgical procedure based on flapless extraction of the intrastromal lenticule created by a femtosecond laser. Central toxic keratopathy is a rare, non-inflammatory complication of flap laser surgery using the femtosecond laser. This disorder is typically characterized by the triad of noninflammatory central corneal opacification, striae, and loss of stromal bed tissue, and it results in a hyperopic shift that causes a reduction in vision quality and it is not among the complications we are familiar with after the SMILE. Because of the growing number of refractive surgical procedures worldwide there may be an increasing incidence of this disorder. A differentiation from an inflammatory or infectious etiology and appropriate treatment is necessary for recovery. In this case report, we report a case of central toxic keratopathy in a 25 years old male patient after SMILE laser surgery.

Ocular Features and Clinical Approach to Cataract and Corneal Refractive Surgery in Patients with Myotonic Dystrophy.

Myotonic dystrophy is the most common inherited muscular dystrophy in adults and presents as two forms, type 1, and type 2. Ocular manifestations such as premature cataract formation, may be the first diagnostic sign or symptom of the disease, offering ophthalmologists a unique diagnostic role. Fuchs' endothelial corneal dystrophy, ptosis and ocular melanoma are other possible findings. Systemic features can help providers better understand the disease and any accommodations to be made in clinical or surgical settings. Some patients with this disease may request evaluation of certain cataract or corneal refractive procedures. This article focuses on pertinent information for clinicians to utilize when evaluating and treating patients with myotonic dystrophy and specific surgical perspectives to consider prior to any ocular interventions. Hydrophobic intraocular lenses are still recommended in these patients with careful observation of capsular phimosis and posterior capsular opacities.

Evaluation of Two Corneal Refractive Surgical Procedures for High Myopia

Evaluation of Two Corneal Refractive Surgical Procedures for High Myopia

Новые возможности диагностического обследования пациентов перед кераторефракционными операциями в условиях пандемии COVID-19

Aim: to assess the reproducibility and comparability of measurements produced by Visionix VX130+ and their consistency with data produced by Topcon KR-800, NT-530P, Oculyzer, and RTVue-100. Patients and Methods: 124 patients (248 eyes) aged 18–45 years (mean age 25.24±7.5 years) were enrolled. Refractometry, IOP levels, and pachymetry measured by Visionix VX130+ system (LLC “Visionix Rus” — affiliated company of Luneau Technology Operations) were compared to the readings produced by Topcon KR-800 Auto Kerato-Refractometer (Topcon, Japan), Nidek NT-530P non-contact tonometer (Nidek, Japan), CT200 Goldman applanation tonometer (Reichert, USA), ALLEGRO Oculyzer (WaveLight AG, Germany), and RTVue-100 (Optovue, USA). Results: refractometry produced by Visionix VX130+ is highly reproducible and stable. Mean spread of spherical equivalent was 0.22±0.22 D and mean spread of cylindrical equivalent was 0.23±0.16 D. No significant differences were revealed between refractometry readings produced by Visionix VX130+ and Topcon KR-800 in patients with myopia (p&gt;0.05). Both Visionix VX130+ and Nidek NT-530P (automated IOP measurements) produce two values, i.e., with and without corneal thickness. Our findings suggest that mean values are virtually similar in Visionix VX130+ group (p&gt;0.05) while Nidek NT-530P produces significant differences (p&lt;0.05). Mean central corneal thickness (CCT) measured by Visionix VX130+ was almost similar to CCT measured by Oculyzer (the difference was 3.8±2.23 μm, р&gt;0.05) and greater than CCT measured by RTVue-100 (р&lt;0.05). Conclusion: clinical trials comparing the readings produced by Visionix VX 130+ and other devices whose reliability was evidenced by long-term clinical experience have demonstrated that Visionix VX 130+ multifunctional diagnostic system is fully in line with the COVID-19 pandemic requirements. This device provides the measurements for performing safe and effective corneal refractive surgery for refractive errors. Keywords: corneal refractive procedure, pneumotonometry, aberrometry, corneal topography, pachymetry, cornea, intraocular pressure. For citation: Sakhnov S.N., Klokova O.A., Piskunov A.V. et al. New avenues of preoperative evaluation before corneal refractive surgery during the COVID-19 pandemic. Russian Journal of Clinical Ophthalmology. 2021;21(2):72–77. DOI: 10.32364/2311-7729-2021-21-2-72-77.

Pharmacological Therapy for Presbyopia in Patients with Previous Corneal Refractive Surgery: A Pilot Study.

PurposeTo perform a pilot evaluation of a novel pharmacological therapy for presbyopia in patients with previous corneal refractive surgery.MethodsThis interventional study included 130 presbyopic patients. The patients were divided into three groups: (1) LASIK group, which included patients with previous LASIK for myopia or hyperopia; (2) previous presbyopia surgery group, including patients with previous monovision or PresbyLASIK (PresbyMAX, SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany); and (3) control group, which included presbyopes without any corneal refractive procedure. The main reason for dividing them into groups is that we hypothesized that the previous presbyopia surgery group may have better outcomes as the patients already have an increased depth of field. The uncorrected near and distance visual acuity was measured before and 2 hours after the binocular instillation of the eye drop (FOV tears), as well as the objective scatter index (OSI), and pupil diameter in photopic and scotopic conditions. Side effects were reported as well.ResultsThere was a statistically significant improvement in the uncorrected near vision in all groups (p = 0.001). Ninety-one percent of the patients included in this study gained at least one line in near vision. All patients in the previous presbyopia surgery group gained at least one line in near vision. Six patients (13.9%) in the LASIK group and five (7.6%) in the control group did not gain any lines of near vision. There was no significant difference in the OSI, there was a significant change in pupil size in scotopic conditions in all groups (p = 0.001), and 5.3% of the patients reported having a headache as a side effect of the therapy.ConclusionsTopical treatment with this pharmacological therapy offers a potential for near vision improvement in patients with previous corneal refractive surgery, especially in those with previous presbyopia surgery.

A review of glycaemic changes on vision in phakic, aphakic and pseudophakic people with diabetes

Background: One of the leading causes of preventable blindness is cataract affecting approximately 18 million people worldwide. Twenty per cent of cataract operations worldwide are performed on people with diabetes mellitus (PDM).Aim: The aim of this review article is to analyse the scientific literature relating to visual changes associated with diabetes mellitus (DM) in pseudophakic, aphakic and phakic people, and to discuss the consequences of these changes for optometrists.Method: A literature search was conducted on PubMed, the University of KwaZulu-Natal Libraries and Google Scholar databases from August 2017 to August 2018.Results: Acute and chronic hyperglycaemia in DM causes myopia in phakic PDM, whilst in aphakic PDM it causes a hyperopic shift in refraction. It has been reported that contrast sensitivity and visual acuity are affected by changes in blood glucose. People with DM have increased central corneal thickness as compared to non-diabetics, whilst only the posterior corneal curvature is affected by hyperglycaemia in PDM. No evidence exists on the effects of glycaemic changes in pseudophakes.Conclusion: It should be noted that high blood glucose level (BGL) induces transient myopia and hyperopia in chronic phakic PDM and aphakic PDM, respectively. All refractive procedures, including prescription of spectacles, corneal refractive procedures and lens extraction, should be deferred until normalisation of BGL in phakic and pseudophakic PDM, as higher sugar levels affect corneal curvature and thickness and overall vision.

Effects of chalazion on corneal astigmatism and wave-front aberrations in Egyptian patients

Aim This study investigated the correlation between chalazion, regarding its size, site and location, and different types of refractive errors, as well as high-order aberrations in Egyptian patients. Patients and methods This is a cross-sectional study which compared 53 eyes from 48 patients having eyelid chalazion with 43 eyes of age-matched control group. Chalazion was classified according to size, site, and location. Refraction was done using an autorefractokeratometer. Corneal topography and aberrations were done using a Scheimpflug topographer. Results The third-order aberration (coma Z31) and fourth-order aberration (secondary astigmatism Z42) were higher in the chalazion group compared with the control group (P=0.035 and 0.035, respectively). Lower lid chalazia showed higher Esafoil aberration Z66 than both upper lid and control group (P=0.015 and 0.001, respectively). In addition, the large-sized chalazion group showed a significant increase in Esafoil aberration Z66 than the small-sized group and the control group (P=0.004 and 0.003, respectively). No difference was observed between the chalazion group and the control group regarding autorefractokeratometer data or topographic data. Conclusion Although the presence of chalazion may not be associated with changes in refraction or corneal astigmatism, it still can cause increase in some high-order aberrations and hence, in the quality of vision. Besides, it is a threat as a source of infection before any surgical procedure. Therefore, it is important to exclude and treat any chalazion before proceeding with any refractive surgery especially wave-front-guided and wave-front-optimized corneal refractive procedures.

Коррекция состояния глазной поверхности у пациентов с синдромом «сухого глаза» на этапе подготовки к кераторефракционной операции

Aim: to analyze the prevalence of dry eye disease (DED) among adult patients with ametropias and the efficacy of its complex treatment when preparing the ocular surface for corneal refractive surgery.Patients and Methods: 1,762 patients with ametropias were examined. In addition to all of the standard eye checks, vital conjunctival and corneal staining, Scheimpflug corneal topography, and anterior segment OCT as well as patient survey were performed. Standard preservative-free tear substitutes with or without a short course of steroids, lubricants, 0.05% anionic cyclosporine emulsion (twice daily), and long-term punctal plugs were prescribed for DED.Results: mild DED was diagnosed in 1,021 patients (57.9%). Of them, corneal lesion was reported in 362 patients (35.4%) and asymptomatic DED in 250 patients (25.5%). Corneal topographic indices of one or both eyes were abnormal (as a result of DED) in 147 patients (14.4%). Significant (p≤0.05) increase in corneal epithelial thickness of one or both eyes was reported in 564 patients (55.2%). Ocular surface treatment in DED patients allowed for uncomplicated corneal refractive procedures while target refraction was achieved in 1,006 patients (98.5%). Conclusion: a complex diagnostic approach to DED involving specific tests, patient survey, corneal topography, and OCT provides the diagnosis of both manifest and latent DED. Combined treatment for conjunctival and corneal xerosis that includes tear substitutes, topical cyclosporine, and punctal plugs, improves ocular surface health in DED thus enlarging the list of indications and the safety of laser eye surgery in these patients.Keywords: dry eye disease, laser eye surgery, corneal refractive procedures, anionic cyclosporine emulsion, punctal plugs, corneal epithelium.For citation: Klokova O.A., Damashauskas R.O., Geidenrich M.S. Ocular surface treatment in dry eye patients before corneal refractive surgery. Russian Journal of Clinical Ophthalmology. 2020;20(4):180–186. DOI: 10.32364/2311-7729-2020-20-4-180-186.

Incidence of Keratoconus in Refractive Surgery Population of Vojvodina - Single Center Study.

Introduction: Keratoconus (KCN) is known to affect all ethnicities but its incidence exhibits geographical variability plausibly due to subclinical forms of the disease, differences in diagnostic methods and criteria, or differences in genetic variations in populations.Aim:To examine the prevalence of keratoconus among the refractive surgery population of Vojvodina, who underwent refractive surgery screening at Eye Clinic Svjetlost Novi Sad, Serbia from September 2018 to September 2019. This is a single-center study.Methods:Retrospective analysis of 876 patients who presented for refractive surgery evaluation. Corneal tomographers represent the gold standard in the detection and classification of corneal ectatic diseases and screening is an essential part of the preoperative diagnostics before any refractive surgery. The corneal tomographer used in this study was a Scheimpflug imaging device (Pentacam AXL, Oculus Optikgeräte GmbH, Wetzlar, Germany). The device was realigned before each measurement.Results:Out of a total number of patients, 619 (70,7%) were candidates for corneal refractive surgery procedure, and 257 patients (29.3%) were not. Out of 257 patients that were not candidates for the procedure 157 (61,0%) patients had thin corneas, high myopia/hypermetropia or had some retinal disease; 75 patients (29,1) were keratoconus suspect and 25 patients (9,7%) had keratoconus. KCN patients had a mean age of 29.5 ± 7.7 years, 18 patients (72.0%) were male and 7 patients were female (28%).Conclusion:The most cited annual incidence of KCN is 2 approximately 1 per 2,000. Recent data from the biggest Netherland study revealed many different epidemiological results which deprive keratoconus of the community of rare diseases. The incidence of keratoconus in Vojvodina refractive surgery population presented in our Clinic was 2.9%.

Refractive surgery with simultaneous collagen cross-linking for borderline corneas - A review of different techniques, their protocols and clinical outcomes.

Simultaneous corneal cross-linking (CXL) has been proposed as an adjunct therapy to corneal refractive procedures to prevent future ectasia, especially when performed in borderline corneas. This review analyses the currently available literature (minimum follow-up 6 months) on corneal refractive surgery and simultaneous CXL (PRK Xtra, LASIK Xtra, and SMILE Xtra) to evaluate the overall results including the safety, efficacy, and potential complications associated with these procedures. A comprehensive literature search of various electronic databases (PubMed, PubMed Central, Cochrane database, and MEDLINE) was performed up to 20th May 2020. Four relevant studies were found for PRK Xtra, 12 for LASIK Xtra, and 3 for SMILE Xtra. The total number of eyes included in this review was 1,512: 294 for PRK Xtra, 221 for PRK-only, 446 eyes for LASIK Xtra, 398 eyes for LASIK-only, 91 for SMILE Xtra and 62 for SMILE-only. Current literature suggests that refractive surgery and simultaneous CXL is generally safe and delivers comparable results in terms of visual and refractive outcomes than refractive surgery alone. However, there is no consensus on a standard cross-linking protocol, and complications such as diffuse lamellar keratitis, central toxic keratopathy, and corneal ectasia following Xtra procedures have been reported. It is therefore suggested that surgeons exercise caution in case-selection and counsel their patients regarding the potential risks and benefits with Xtra procedures. Also, further studies are required to standardize the UV-A irradiation protocols and to evaluate the long-term effect on safety, refractive predictability, and stability of these procedures.