Factors affecting long-term myopic regression after corneal refractive surgery for civilian pilots in southwest China.

BACKGROUND: The purpose of this study was to analyze myopic regression after corneal refractive surgery (CRS) in civilian pilots and to explore the factors that may cause long-term myopic regression. METHODS: We included civilian pilots who had undergone CRS to correct their myopia and who had at least 5 years of follow-up. We collected retrospective data and completed eye examinations and a questionnaire to assess their eye habits. RESULTS: A total of 236 eyes were evaluated in this study. 211 eyes had Intrastromal ablations (167 eyes had laser in situ keratomileusis, LASIK, 44 eyes had small incision lenticule extraction, SMILE) and 25 eyes had subepithelial ablations (15 eyes had laser epithelial keratomileusis, LASEK and 10 eyes had photorefractive keratectomy, PRK). The mean preoperative spherical equivalent (SE) was - 2.92 ± 1.11 D (range from - 1.00 to -5.00 D). A total of 56 eyes (23.6%) suffered from myopic regression after CRS. Comparisons of individual and eye characteristics between the regression and non-regression groups revealed statistically significant differences in age, cumulative flight time, postoperative SE (at 6 months and current), uncorrected visual acuity (UCVA), accommodative amplitude (AA), positive relative accommodation (PRA), postoperative period, types of CRS and eye habits. Generalized propensity score weighting (GPSW) was used to balance the distribution of covariates among different age levels, types of CRS, cumulative flying time, postoperative period and continuous near-work time. The results of GPS weighted logistic regression demonstrated that the associations between age and myopic regression, types of CRS and myopic regression, continuous near-work time and myopic regression were significant. Cumulative flying time and myopic regression, postoperative period and myopic regression were no significant. Specifically, the odds ratio (OR) for age was 1.151 (P = 0.022), and the OR for type of CRS was 2.769 (P < 0.001). The OR for continuous near-work time was 0.635 with a P value of 0.038. CONCLUSIONS: This is the first report to analyze myopic regression after CRS in civilian pilots. Our study found that for each year increase in age, the risk of civilian pilots experiencing myopic regression was increased. Intrastromal ablations had a lower risk of long-term myopia regression than subepithelial ablations. There is a higher risk of myopic progression with continuous near-work time > 45 min and poor accommodative function may be related factors in this specific population.

Refraction and topographic risk factors for early myopic regression after small-incision lenticule extraction surgery.

We sought to evaluate the topographic risk factors for early myopic regression after small-incision lenticule extraction (SMILE). A retrospective case‒control study was conducted, and individuals who underwent SMILE surgery were enrolled. Among them, 406 and 14 eyes were categorized into the nonregression and regression groups, respectively. The preoperative and postoperative parameters in the two groups were collected, including spherical refraction (SE), axial length (AXL) and topographic data. A generalized linear model was adopted to analyze the difference in each parameter between the two groups. After 6 months, UCVA decreased in the regression group, and SE increased in the regression group (both P < 0.05). The increase in the CCT at the thinnest point (P = 0.044), flat corneal curvature (P = 0.012) and TCRP (P = 0.001) were significantly greater in the regression group. Regarding the risk factors for myopic regression, preoperative SE, preoperative sphere power, preoperative AXL, preoperative flat corneal curvature, preoperative SA, early postoperative SE, early postoperative sphere power, early postoperative AXL and early postoperative CCT difference were significantly greater in the regression group (all P < 0.05). The SE, sphere power, AXL, preoperative flat corneal curvature, preoperative SA, and postoperative CCT difference correlate with early myopic regression after SMILE.

A nursing report on a corneal contact lens wearer receiving keratoplasty due to corneal ulcer and perforation caused by Pythium insidiosum infection: A case report.

BACKGROUND: To report the nursing experience of a case of corneal contact lens wearer receiving the 2nd keratoplasty due to corneal ulcer and perforation caused by Pythium insidiosum infection. METHODS: A 30-year-old female patient had blurred vision after deep anterior lamellar keratoplasty for a right corneal ulcer. At the 5th week, the right eye appeared the symptoms, such as redness and pain. The anterior segment photography was performed on the eye, and the result showed that the epithelium was missing in the right eye lesion area, and a large number of longitudinal and transversal streaks were visible from the epithelium to the stroma, with fungus filaments to be discharged. Upon macro-genome sequencing of the corneal secretion, a P. insidiosum infection was observed. Then, the patient underwent the keratoplasty, and 3 weeks later, the corneal implant showed a tendency to dissolve, the sutures were partially loosened, and the eye was almost blind. Subsequently, the patient was admitted to our hospital and subject to the 2nd penetrating keratoplasty of the right eye (allograft). After surgery, linezolid and azithromycin injections were given through intravenous drip and local drip of the eye for anti-inflammation, and tacrolimus eye drops for antirejection. RESULTS: Postoperatively, the patient showed signs of recovery with slight corneal edema and visible pupil, leading to discharge with improved vision. The corneal implant was normal 1 week after surgery and the vision of the right eye was hand move/before eye at the 6th month of follow-up. Continuous care and removal of sutures 3 months post-surgery contributed to a successful outcome, with the patient achieving hand motion vision 6 months after the procedure. CONCLUSION: Corneal ulcer caused by P. insidiosum infection not only needs timely and effective keratoplasty intervention, but also requires perfect nursing measures.

Laser in Situ Keratomileusis Flap Free-Floating on Interface Edema in Acute Corneal Hydrops.

This case report describes a patient with a history of laser in situ keratomileusis who presented with pain, photophobia, and blurred vision secondary to a corneal flap free-floating on interface edema in the setting of acute hydrops.

Effect of upper eyelid blepharoplasty on the ocular surface, tear film, and corneal microstructure.

PURPOSE: This study aimed to investigate the effect of upper eyelid blepharoplasty with the removal of the skin and a strip of orbicularis oculi muscle on the ocular surface, tear film, and dry eye-related symptoms. METHODS: Twenty-two eyes of 22 consecutive patients operated by a single surgeon (21 females; mean age, 61 years; age range, 41-75 years) were included. All subjects completed the Ocular Surface Disease Index questionnaire, underwent in vivo confocal microscopy, tear film breakup time measurements, the Schirmer test with anesthesia, and fluorescein and lissamine green staining measurements before, 1 month, and 6 months after upper blepharoplasty alone with preseptal orbicularis excision. RESULTS: A significant increase in Ocular Surface Disease Index, and corneal fluorescein and lissamine green staining and a significant decrease in tear film breakup time were observed after 1 month (p=0.003, p=0.004, p=0.029, and p=0.024 respectively) and 6 months (p=0.001 for all findings). No significant difference in the Schirmer test score was observed during the follow-up. None of the in vivo confocal microscopy parameters showed significant changes during the study. CONCLUSIONS: An increase in dry eye symptoms and a decrease in tear film stability along with ocular surface staining were observed in patients undergoing upper eyelid blepharoplasty.

Corset suture: A novel technique of overlay appositional continuous sutures with air tamponade for management of large acute corneal hydrops.

Management of large acute corneal hydrops (ACH) has always been a challenge. Various medical and surgical management options have been used, such as topical steroids, cycloplegics, antiglaucoma medications, antibiotics, Descemet's membrane reposition, and pre-Descematic sutures, for the management of acute hydrops, but have shown limited benefit. We hereby describe a novel technique of appositional continuous overlay sutures along with air tamponade for surgical management of corneal edema following large ACH. In this technique, the epithelium is scraped to visualize the stromal cleft, and then corneal marking is done to locate the suture placement site. Next, a continuous overlay, 10-0 nylon suture is passed in a crisscross fashion, just like the laces of a corset. A small paracentesis is made to lower the intraocular pressure. Stromal fluid is milked out using two iris spatulas, simultaneous suture tension adjustment is done, and the knot is secured. Appropriate anterior chamber tamponade is achieved using air, paracentesis is hydrated, and a bandage contact lens is applied. We noted complete resolution of corneal edema within 2 weeks of the procedure, with significant improvement in visual acuity.

New forays into measurement of ocular biomechanics.

PURPOSE OF REVIEW: The field of corneal biomechanics has rapidly progressed in recent years, reflecting technological advances and an increased understanding of the clinical significance of measuring these properties. This review will evaluate in-vivo biomechanical properties obtained by current technologies and compare them regarding their relevance to established biomechanical properties obtained by gold-standard ex-vivo techniques normally conducted on elastic materials. RECENT FINDINGS: Several new technologies have appeared in recent years, including vibrational optical coherence tomography (VOCT) and the corneal indentation device (CID). These techniques provide promising new opportunities for minimally invasive and accurate measurements of corneal viscoelastic properties. SUMMARY: Alterations in corneal biomechanics are known to occur in several corneal degenerative diseases and after refractive surgical procedures. The measurement of corneal biomechanical properties has the capability to diagnose early disease and monitor corneal disease progression. Several new technologies have emerged in recent years, allowing for more accurate and less invasive measurements of corneal biomechanical properties, most notably the elastic modulus.

UV light-mediated corneal crosslinking as (lymph)angioregressive pretreatment to promote graft survival after subsequent high-risk corneal transplantation (CrossCornealVision): protocol for a multicenter, randomized controlled trial.

BACKGROUND: Good vision highly depends on the transparency of the cornea, which is the "windscreen" of the eye. In fact, corneal blindness due to transparency loss is the second most common cause of blindness worldwide, and corneal transplantation is the main cure. Importantly, the cornea is normally avascular but can secondarily be invaded by pathological (blood and lymphatic) vessels due to severe inflammation, and the survival prognosis of a corneal graft mainly depends on the preoperative vascular condition of the recipient's cornea. Whereas transplants placed into avascular recipient beds enjoy long-term survival rates of > 90%, survival rates significantly decrease in pathologically pre-vascularized, so-called high-risk recipients, which account for around 10% of all performed transplants in Germany and > 75% in lower and middle-income countries worldwide. METHODS: This parallel-grouped, open-randomized, multicenter, prospective controlled exploratory investigator-initiated trial (IIT) intends to improve graft survival by preconditioning pathologically vascularized recipient corneas by (lymph)angioregressive treatment before high-risk corneal transplantation. For this purpose, corneal crosslinking (CXL) will be used, which has been shown to potently regress corneal blood and lymphatic vessels. Prior to transplantation, patients will be randomized into 2 groups: (1) CXL (intervention) or (2) no pretreatment (control). CXL will be repeated once if insufficient reduction of corneal neovascularization should be observed. All patients (both groups) will then undergo corneal transplantation. In the intervention group, remaining blood vessels will be additionally regressed using fine needle diathermy (on the day of transplantation). Afterwards, the incidence of graft rejection episodes will be evaluated for 24 months (primary endpoint). Overall graft survival, as well as regression of corneal vessels and/or recurrence, among other factors, will be analyzed (secondary endpoints). DISCUSSION: Based on preclinical and early pilot clinical evidence, we want to test the novel concept of temporary (lymph)angioregressive pretreatment of high-risk eyes by CXL to promote subsequent corneal graft survival. So far, there is no evidence-based approach to reliably improve graft survival in the high-risk corneal transplantation setting available in clinical routine. If successful, this approach will be the first to promote graft survival in high-risk transplants. It will significantly improve vision and quality of life in patients suffering from corneal blindness. TRIAL REGISTRATION: ClinicalTrials.gov NCT05870566. Registered on 22 May 2023.

[Intracorneal selective stromal transplantation]. / Vnutrirogovichnaya transplantatsiya stromy.

Deep anterior lamellar keratoplasty or penetrating keratoplasty are currently considered the optimal methods of surgical treatment of stromal dystrophies and corneal degeneration. Despite certain advantages and benefits of these methods, they also have significant limitations: involvement of superficial corneal layers in the surgery, need for suturing, development of post-keratoplasty astigmatism etc. PURPOSE: This study aimed to test and describe the new method of closed sutureless keratoplasty (intracorneal selective stromal transplantation), which was indicated in isolated dystrophic and degenerative pathology of the stroma. MATERIAL AND METHODS: Intracorneal selective stromal transplantation was performed in a 62-year-old patient with stromal degeneration and intact corneal layers between the altered stroma and the Descemet's membrane posteriorly, and the Bowman's layer anteriorly. The patient also had immature senile cataract. Corneal stroma was removed and replaced with a graft in the optical center of the lens, while the endothelium, the Descemet's membrane and the Bowman's layer remained intact. RESULTS: The proposed technique of intracorneal selective stromal transplantation makes it possible to replace only the pathologically altered stroma through closed surgical approach, without affecting the anterior and posterior surfaces of the cornea. Best-corrected visual acuity has increased in the patient from 0.01 to 0.6, while mean endothelial cell density has not changed in the course of 24-months follow-up. CONCLUSION: The proposed keratoplasty method can be used in patients with dystrophy or degeneration of the corneal stroma and preserved endothelial cells, intact Descemet's membrane and Bowman layer. Since the superficial corneal layers are not involved during the surgery, intracorneal selective stromal transplantation combined the advantages of both deep anterior lamellar keratoplasty and endothelial keratoplasty. The biologically favorable result in this first clinical case allows a preliminary conclusion on the technical possibility and functional effectiveness of the proposed method, but further long-term observation and more clinical cases are required.

Fourier analysis of corneal irregular astigmatism after small-incision lenticule extraction and transepithelial photorefractive keratectomy: A comparative study.

To compare changes in the spherical component, regular astigmatism, and irregular astigmatism of the anterior surface of the cornea after small-incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (TransPRK). Fifty-six patients underwent SMILE in 56 eyes, and 68 patients underwet TransPRK in 68 eyes. The right eye was chosen to enter the group. Six months after the procedure, Scheimpflug images were acquired, and Fourier analysis of the anterior surface of patients' corneas was performed using the Pentacam built-in software. Fourier parameters encompass various measurements such as the steepest radius of the curvature and average eccentricity of the spherical components (SphRmin and SphEcc), maximum decentration (MaxDec), central and peripheral regular astigmatism (regular astigmatism at the center [AstC] and regular astigmatism at the periphery [AstP]), and irregularity (Irr). At 6 months postoperatively, SphEcc decreased significantly (P < .001), MaxDec increased significantly (P < .001), and Irr increased insignificantly (P = .254) in the SMILE group. SphEcc decreased significantly (P < .001) and MaxDec and Irr increased significantly (P < .001) in the TransPRK group. TransPRK caused greater changes in SphEcc, MaxDec, and Irr on the anterior corneal surface than SMILE (P < .05). The amount of MaxDec-induced changes in SMILE and TransPRK was significantly correlated with the amount of higher-order aberrations and spherical aberration changes (P < .05). SMILE and TransPRK increase overall irregular astigmatism on the anterior surface of the cornea, more so with TransPRK, where changes in decentration are associated with with increased higher-order aberrations.

[Peripheral sterile corneal infiltrates after small incision lenticule extraction].

A 31-year-old female patient with refractive error in both eyes underwent small incision lenticule extraction. On the 4th day after surgery, arc-shaped peripheral corneal infiltrates appeared in the right eye. Tobramycin and dexamethasone eye drops, 0.3% gatifloxacin eye drops, and a corneal bandage lens were applied to the eye. After bacterial infection was ruled out, dexamethasone sodium phosphate was injected subconjunctivally near the corneal lesion. The symptoms improved and the corneal lesion subsided afterwards.

Dealing With Pericylindrical Melts in Keratoprosthesis: Tenon Patch Graft to the Rescue.

PURPOSE: The aim of this study was to describe the outcomes of autologous Tenon patch graft in the management of Auro keratoprosthesis-related pericylindrical corneal melt. METHODS: We report 3 cases of sterile pericylindrical corneal melt in patients with Auro keratoprosthesis implantation after a mean duration of 5 years (1.5-8 years). Case 1 was a patient with severe graft-versus-host disease. Cases 2 and 3 were cases of chemical injury.All these cases of sterile pericylindrical corneal melt (4-6 mm) underwent autologous Tenon patch graft. The technique included freshening of the edges around the melt, followed by measuring the size of the defect. A Tenon graft harvested from the patient's own eye was used to seal the defect and act as a scaffold. The Tenon patch graft was spread over the melt and held in place by the application of fibrin glue and/or interrupted 10-0 nylon sutures. A bandage contact lens was then placed on the eye. RESULTS: Tenon patch graft was well taken in all patients. The mean duration of epithelial healing was 1 month. Globe integrity was well maintained with no postoperative complications at a mean follow-up duration of 12 months (6-18 months). CONCLUSIONS: Corneal melt is one of the most dreaded complications of KPro because its occurrence could threaten visual prognosis and globe integrity. Autologous Tenon patch is a simple yet innovative and effective option to steer such eyes away from potentially dreadful complications.

Intraoperative collagen imaging of sutured cornea: A way towards managing post-penetrating keratoplasty astigmatism.

The birefringent nature of the human cornea plays an important role in comprehending its structural behavior in both diseased and surgical conditions. During corneal transplantation, irregular astigmatism is a common post-surgical complication that depends on the characteristics of suturing. Four human cadaver corneas are subjected to an in-vitro model of a typical full-thickness penetrating keratoplasty (PK) procedure using 16 simple interrupted 10-0 vicyrl sutures. The birefringence of these four corneas is analyzed using digital photoelasticity and compared with the control cornea (without PK). It is found that the sutures and their mutual interaction influence the morphology of the peripheral birefringence of the cornea. The findings of the present investigation are pertinent to intraoperative suture management during PK. Results suggest conserving the typical diamond-shaped morphology of peripheral birefringence would ensure uniform distribution of sutures. Therefore, birefringence imaging could be useful in suture management to ensure proper apposition of the graft-host junction, thus minimizing the risk of irregular astigmatism.

Severe Corneal Damage After Minor Eyelid Surgery: A Case Series.

OBJECTIVES: To present three cases of serious corneal complications after seemingly minor and uncomplicated eyelid surgery. METHODS: These cases emphasize the real-world risk of corneal damage after oculoplastic surgery. RESULTS: The first case is a 46-year-old man referred to our department with a corneal perforation after bilateral blepharoplasty of both upper and lower eyelids. The second case concerns a 51-year-old woman who suffered an accidental coagulation of the cornea during the removal of upper eyelid papillomas, and the third case is a 55-year-old woman who had severe corneal thinning accompanied by visual loss after an upper lid blepharoplasty. All patients were stabilized without the need for corneal transplantation, although there were significant corneal scars and sequelae. CONCLUSIONS: Although complications after esthetic oculoplastic surgery are rare, the reported cases show that corneal damage can have a major impact on the patient's vision and quality of life. Strategies such as the use of a corneal shield can be used to mitigate these risks, but their use is debated. Nevertheless, diligent postoperative care is paramount. At the first postoperative visit, a basic visual acuity measurement should be performed. In cases where reduced vision is reported, particularly when accompanied by pain, patients should be urgently referred for specialized eye care.

Impact of removing soft contact lenses 1 day versus 1 month before surgery on the outcomes of microkeratome laser in situ keratomileusis.

PURPOSE: To compare the outcomes, safety, efficacy, and predictability of microkeratome laser in situ keratomileusis (LASIK) 24 h and one month or more after removing soft contact lenses. SETTING: ULTRALASIK Eye Center, Dubai, United Arab Emirates. METHODS: The patients were divided based on the time of discontinuation of the soft contact lenses before LASIK (Group 1 at 24 h and Group 2 at one month or longer), and the two groups were well matched. Schirmer's testing, tear break-up time, corrected distance visual acuity, uncorrected distance visual acuity, manifest refraction spherical equivalent, and infection rate were evaluated preoperatively and at one week, one month, and six months after treatment. RESULTS: Group 1 (G1) comprised 1025 eyes, and group 2 (G2) had 1052 eyes. The groups were comparable preoperatively. The overall-mentioned outcomes were comparable between groups with uncorrected distance visual acuity of - 0.084 ± 0.12 logMAR in G1 and - 0.078 ± 0.17 logMAR in the G2 at 6 months (P = 0.322). Tear break-up time as well as Schirmer's testing results was also comparable with no evidence of increased risk of dry eyes or non-inflammatory complications in any of the groups on follow-up visits at 1 week (P = 0.421), 1 month (P = 0.101), and 6 months (P = 0.399) postoperatively. Finally, no infectious complications were recorded in either of the groups. CONCLUSION: With the absence of corneal warpage, no statistical or clinical difference in microkeratome LASIK outcomes and safety was spotted between the groups despite the difference in SCL discontinuation time before the procedure.

Refractive outcomes of small lenticule extraction (SMILE) Pro® with a 2 MHz femtosecond laser.

PURPOSE: To evaluate the initial visual outcomes of Small Incision Lenticule Extraction (SMILE) Pro® using a 2 MHz femtosecond laser (VisuMax 800, Carl Zeiss Meditec) and to assess the efficacy, safety, predictability, accuracy, and complication rate. METHODS: This retrospective analysis included eyes which underwent the SMILE Pro® procedure using VisuMax 800 femtosecond laser to correct myopia. All surgeries were performed by one surgeon (DB). Follow-up was conducted 3 months postoperatively to evaluate visual outcomes after neuroadaptation, corrected visual acuity (CDVA) and intra- and postoperative complications. RESULTS: One hundred and fifty-two eyes of 82 patients (mean age 31 ± 6 years) results at 3 months are presented. The mean spherical equivalent (SE) was - 4.44 ± 1.86 D preoperatively while -0.24 ± 0.32 D postoperatively. 99% of eyes achieved SE within ± 1.0 D of attempted correction and 91% were within ± 0.5 D. Efficacy index was 0.93 while the safety index was 1. No complications occurred intra- or postoperatively. No eyes lost more than 1 line of their preoperative CDVA. All highly myopic eyes (- 6.25 to - 10.00 D; n = 18) achieved 20/20 at 3 months postoperatively and were within 0.5 D from the attempted SE and no eyes lost more than 1 line of CDVA. CONCLUSION: The SMILE Pro® is a safe, efficient, and predictable procedure for the treatment of myopia and myopic astigmatism, with comparable results of conventional SMILE surgery. High myopic eyes achieve better results than low and moderate myopia. No complications were recorded in our patients.

The Effects of Whole-Corneal and Whole-Eye Higher Order Aberrations on the Discrepancy Between Refractive and Corneal Astigmatism in Otherwise Healthy Candidates for Refractive Surgery.

PURPOSE: To evaluate the effect of different whole-corneal and whole-eye higher order aberrations (HOAs) on levels of axis discrepancy. METHODS: This was a retrospective study including healthy candidates for refractive surgery, with one eye being randomly selected. A total of 360 eyes were included. Whole-corneal and whole-eye HOAs were measured twice with a Pentacam AXL Wave (Oculus Optikgeräte GmbH), and subjective manifest refraction was obtained. Axis discrepancy was defined as the absolute difference between Total Corneal Refractive Power flat keratometry axis and manifest refractive axis. Two multiple linear regression models that sought to explore the effect of HOAs in predicting axis discrepancy while adjusting for corneal and refractive confounders were built. RESULTS: Mean age was 29.1 ± 5.8 years and 63.9% of the patients were women. Mean manifest sphere and cylinder were -3.09 ± 2.36 and -1.45 ± 1.37 diopters (D), respectively. Mean cylinder axis discrepancy was 14.4 ± 14.5°. On multiple linear regression, the only variables significantly associated with axis discrepancy were corneal cylinder and corneal lower order aberrations [F(5,339) = 29.746; P < .001; adjusted R2 = 0.295]. Lower levels of corneal cylinder are by far the main contributor to astigmatism axis mismatch (ß = -1.164). There was not a single HOA, either corneal or ocular, that significantly loaded into any models. CONCLUSIONS: Astigmatism axis mismatch decreases rapidly with increasing levels of corneal astigmatism. Corneal and whole-eye HOAs have no role in astigmatism axis mismatch in healthy candidates for refractive surgery. [J Refract Surg. 2024;40(2):e89-e97.].

Factors Predicting the Need for Re-treatment After Laser Refractive Surgery in Patients With Mixed Astigmatism.

PURPOSE: To identify risk factors that increase the likelihood of re-treatment following refractive surgery in patients with mixed astigmatism. METHODS: This was a retrospective study including patients who underwent either laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between 2000 and 2019 and had mixed astigmatism (spherical error of +0.50 D or greater and spherical equivalent of less than 0.00 diopters [D]). Patients were divided into two groups according to whether they underwent re-treatments during the study period. RESULTS: Overall, 785 eyes (785 patients) were included. In total, 5.2% of the eyes (n = 41) underwent re-treatment. The re-treatment group was more likely to have preoperative high astigmatism (80.5% vs 48.3%, P < .001), moderate to high hyperopia (36.6% vs 22.3%, P = .035), and to have undergone surgery earlier during the study period (P < .001). They were also more likely to have undergone surgery using the Wave-Light EX200 rather than the EX500 laser platform (Alcon Laboratories, Inc) (P < .001), have a treated optical zone of 6 mm rather than 6.5 mm (P < .001 for both), and their maximum ablation depth was greater (P < .001). There was no difference between the re-treatment and control groups regarding procedure type (PRK vs LASIK). Binary logistic regression found preoperative high astigmatism (odds ratio = 3.97, P < .001) and the type of laser platform used (EX200, odds ratio = 7.78, P < .001) as the only independent factors associated with re-treatment. CONCLUSIONS: Re-treatment rates following correction of mixed astigmatism were 5.2% over 20 years. Use of a sixth-generation laser platform significantly reduced the risk of re-treatment. Presence of high astigmatism is a significant risk factor for re-treatment. There was no difference in retreatment risk between PRK and LASIK. [J Refract Surg. 2024;40(2):e73-e78.].

Pediatric keratoconus epidemiology: a systematic scoping review.

BACKGROUND: Pediatric keratoconus (pediatric KC) causes progressive deformation of the cornea in children and adolescents, leading to a gradual loss of vision and a need for rehabilitation. However, new treatments may halt the disease and prevent worse outcomes that require penetrating keratoplasty and its associated morbidity and high cost, irreversible loss of vision, and amblyopia. Few systematic reviews focus on keratoconus-and even fewer, on pediatric KC. METHODS: Here, we report a systematic scoping review of pediatric KC epidemiology and discuss the studies reporting data on pediatric KC. We used PRISMA-ScR methodology and checklists in the elaboration of the manuscript. The inclusion criteria were: English language; publication between August 7, 1998, and August 7, 2019 (20 years); theme of the study pediatric KC epidemiology. The search strategy: searches of the PubMed-MEDLINE database and Cochrane Database of Systematic Reviews, using eight combinations of the following MeSH terms: keratoconus; child; incidence; prevalence; pediatrics; adolescent; epidemiology. RESULTS: We charted and reviewed the selected articles. Initial searches included 1802 records; after the exclusion of article duplicates, we screened 777 records, read 97 articles in full text, and included 76 articles in this review. CONCLUSIONS: Recent epidemiological studies with better methodologies demonstrated increased prevalence rates in comparison to the older literature. This effect may be due to better diagnostic methods and better sample selection than those in historical studies. Diagnosis remains a major challenge as the early disease is usually asymptomatic. Economic and social aspects of pediatric KC remain understudied in the pediatric literature. Global, inclusive, and proactive screening studies in schools are imperative to better understand the great impact of this disease in the young.