Correction Of Myopia Research Articles

Femtosecond laser-assisted in situ keratomileusis versus small-incision lenticule extraction: current approach based on evidence.

Laser keratorefractive surgery achieves excellent visual outcomes for refractive error correction. With femtosecond laser, small incision lenticule extraction (SMILE) is an increasingly viable alternative to laser-assisted in situ keratomileusis (LASIK). Comparative studies demonstrate similar efficacy and predictability between SMILE and LASIK, making it difficult for clinicians to choose which to use. This review thus compares femtosecond-LASIK (FS-LASK) and SMILE in various scenarios, to assist clinicians in deciding which refractive surgery procedure to recommend. SMILE may be superior for highly myopic eyes due to a smaller decrease in functional optical zone. SMILE further induces less spherical aberration and less overall higher order aberrations in mesopic conditions. SMIILE also has less postoperative dry eye, making it suitable those with preexisting dry eye. For low to moderate myopic astigmatism correction, FS-LASIK has less undercorrection compared to SMILE. Lastly, SMILE has not yet received Food and Drug Administration or Conformité Européenne approval for hyperopic correction, rendering FS-LASIK the choice of procedure for hyperopic correction. Both FS-LASIK and SMILE demonstrate good efficacy and predictability. Understanding specific clinical scenarios where one may be superior to the other will aid clinicians in choosing the most suitable procedure for personalized care.

Comparison of refractive surgeries (SMILE, LASIK, and PRK) with and without corneal crosslinking: systematic review and meta-analysis.

Corneal crosslinking (CXL) is used for treating keratoconus and post-laser in situ keratomileusis ectasia. However, refractive surgery is not usually performed with prophylactic CXL. Therefore, we performed a meta-analysis comparing outcomes of refractive surgeries with vs without prophylactic CXL. We systematically searched databases for studies comparing refractive surgeries for myopic correction with vs without prophylactic corneal crosslinking. Review Manager 5.4.1 was used to perform statistical analysis. We included 2820 eyes from 28 studies. Compared with refractive surgery alone, surgery with prophylactic CXL resulted in decreased central corneal thickness, corrected distance visual acuity logMAR, and safety and efficacy indices. There were no significant differences in postoperative uncorrected distance visual acuity of 20/20 or better at ≥12 months and other visual outcomes among both groups. More randomized controlled trials with standard crosslinking protocols are needed to analyze the prophylactic use of crosslinking with refractive surgeries.

The use of digital devices and changing habits among generation alpha in Hungary

AbstractPurposeThe aim of the study was to analyse the use of digital devices among children.Materials/MethodsA specially designed questionnaire was distributed to 249 schoolchildren to assess their use of digital devices both in school and outside school. The questionnaire was used before the start of the COVID-19 pandemic. The children were asked about the extent of their use of digital devices, as well as about ophthalmic and general health complaints. Their responses were assessed statistically.ResultsRegarding age distribution, 145 children were between seven and 10 years old when they started to use digital devices. Most of the children used a digital device for between one and two hours a day. The majority preferred using smartphones. The second most popular devices were laptops and tablets, and the third most popular was the desktop computer. Fifty-six children wore glasses, 14 to correct hyperopia and 42 to correct myopia. 97 children spent between one and two hours a day outdoors; 99 children spent more than two hours outdoors; and 51 spent less than one hour outdoors. 71 children reported eye problems; 48 reported other general health problems (back and neck pain); and 43 mentioned blurred vision while using a digital device.ConclusionsThe use of digital devices can be regarded as general among schoolchildren, and most children use a digital device for longer than the recommended time. Excessive use of digital devices may contribute to an increase in the prevalence of myopia and other general eye and back problems.

Biomechanical changes after keratorefractive lenticule extraction with CLEAR and after femtosecond LASIK, correlated with optical coherence tomography findings

The aim of this retrospective, comparative, single-eye study was to assess the biomechanical changes after laser correction of myopia by keratorefractive lenticule extraction (KLEx) and by femtosecond LASIK (FS-LASIK), correlating them with the stromal changes on anterior segment optical coherence tomography. Corneal biomechanical parameters, provided by the high-speed Scheimpflug camera CorVis-ST (Oculus Optikgeräte GmbH) and measured pre-operatively and 1 week post-operatively, were: stiffness parameter at first applanation (SP-A1), stress-strain index (SSI), inverse integrated radius (IIR), deformation amplitude ratio at 2 mm (DA ratio-2mm). A total of 79 eyes undergone KLEx (CLEAR, Ziemer Group) and 93 eyes undergone FS-LASIK were included. The mean residual stromal bed (RSB) was 271.36±17.22 µm after KLEx and 304.21±21.82 µm after FS-LASIK (p=0.00). All parameters in both groups showed statistically significant post-operative changes (p=0.00), except for SSI after FS-LASIK (p=0.39). The percent changes in all parameters were significantly higher in the KLEx group. Even in the eyes with equal RSB (300±5 µm; 19 eyes post-KLEx, 26 eyes post-FS-LASIK), changes were significantly higher after KLEx (SP-A1: -35.9%; SSI: -6.7%) than after FS-LASIK (SP-A1: -29.6%; SSI: -3.8%) (respectively, p=0.02, and p=0.00). In KLEx, reduction in stromal thickness had a weak correlation with reduction in SP-A1 (r=0.39), and poor correlation with reduction in SSI (r=0.26). In conclusion, stiffness parameters were significantly worse after KLEx than after FS-LASIK, even in eyes ending with similar RSB. These findings should be valued cautiously, as the CorVis-ST might not capture all the clinically significant alterations, especially in the post-KLEx bi-layered cornea.

Comparative Analysis of Visual Outcomes and Complications in Intraocular Collamer Lens, Small-Incision Lenticule Extraction, and Laser-Assisted In Situ Keratomileusis Surgeries: A Comprehensive Review.

This review provides a comparative analysis of visual outcomes and complications associated with three prominent refractive surgical techniques: intraocular collamer lens (ICL) implantation, small-incision lenticule extraction (SMILE), and laser-assisted in situ keratomileusis (LASIK). Refractive surgeries aim to correct myopia, hyperopia, and astigmatism, offering patients an alternative to corrective lenses. The review highlights the importance of comparing these procedures to guide clinical decision-making effectively. Each technique is described, emphasizing its unique advantages and considerations. While LASIK remains widely favored for its rapid visual recovery and high patient satisfaction, ICL is suitable for patients with higher refractive errors or corneal irregularities. Although relatively newer, SMILE shows promise with potential benefits such as corneal biomechanical stability and a reduced risk of dry eye syndrome. However, each procedure carries its distinct complications, reinforcing the need for personalized patient care and informed decision-making. Understanding these techniques' relative efficacy and safety profiles is essential for optimizing outcomes and enhancing patient satisfaction. Continued advancements in technology and surgical techniques promise further improvements in refractive surgery outcomes, underscoring the importance of ongoing research and innovation.

CLEAR или ФемтоЛАЗИК?

Purpose. To present a clinical case of FemtoLASIK operation after vacuum loss during CLEAR technique. Methods. During the CLEAR operation for correction of middle degree myopia there was a vacuum loss during the formation of the lower surface of the lenticule. The surgeon decided not to proceed with further CLEAR surgery, but to switch to FemtoLASIK surgery with the formation of a surface flap with a diameter larger than the lenticule diameter and a thickness smaller than the initial planned lenticule depth. Results. The operation was performed without complications, according to the standard protocol, without changing the energy parameters at the femtosecond stage of epithelial-stromal flap formation. When assessing clinical and functional parameters on the next day and in 7 days the uncorrected visual acuity of 1.0 and the planned target refraction were noted. Conclusion. The combination of femtosecond laser technologies allows to solve intraorefractive problems without loss of efficiency and safety. Key words: vacuum loss, femtosecond laser, refractive lenticule extraction

Comparative visual outcomes of the first versus second eye following small-incision lenticule extraction (SMILE)

BackgroundThis study aimed to compare the visual outcomes of the first operated eyes with those of the second operated eyes following small-incision lenticule extraction (SMILE).MethodsA total of 202 patients (404 eyes) underwent SMILE using the tear film mark centration method for myopia and myopic astigmatism correction. Baseline characteristics, objective optical quality, decentered displacement, induced corneal aberrations, and modulation transfer function (MTF) values were assessed. Linear regression analyzed the relationship between decentration and visual quality parameters, including corneal aberrations and MTF values.ResultsNo significant difference was observed in objective visual quality, efficacy, and safety indexes between the two groups (all P > 0.05). The average decentered displacement for the first and second surgical eyes was 0.278 ± 0.17 mm and 0.315 ± 0.15 mm, respectively (P = 0.002). The horizontal coma in the first surgical eyes were notably lower than in the second (P = 0.000). MTF values at spatial frequencies of 5, 10, 15, and 20 cycles/degree (c/d) were higher in the first surgical eyes compared to the second (all P < 0.05). Linear regression indicated that high-order aberrations (HOAs), root mean square (RMS) coma, spherical aberration, horizontal coma, vertical coma, and eccentric displacement were all linearly correlated. Furthermore, MTF values exhibited a linear relationship with eccentric displacement across these spatial frequencies.ConclusionsThere was no discernible difference in visual acuity, efficacy, or safety between the two operated eyes. Nonetheless, the first operated eyes exhibited reduced decentered displacement and demonstrated superior outcomes in terms of horizontal coma and MTF values compared to the second operated eyes following SMILE. The variations in visual quality parameters were linearly correlated with decentered displacement.

Bibliometric and visualized analysis of posterior chamber phakic intraocular lens research between 2003 and 2023.

Myopia is causing a major public health concern, with its prevalence increasing globally. This study aimed to discuss posterior chamber phakic intraocular lens (pIOL) research publication trends and hotspots over the past 20 years. Bibliometric analysis was performed using the Web Science Core Collection to investigate posterior-chamber pIOL research publication trends. The extracted records were analyzed, and a knowledge map was built using VOSviewer v.1.6.20. The analysis included visualizing the annual publication count, countries/regions distribution, international and institutional collaborations, author productivity, and journal contribution, in addition to identifying knowledge bases and hotspots. Burst keywords were extracted using CiteSpace v.6.1.R. In total, 791 articles on posterior chamber pIOLs published between 2003 and 2023 were retrieved. China had the highest number of publications, whereas Japanese papers received the most citations. Fudan University had the highest number of publications, with articles from Kitasato University having the highest number of citations. Regarding individual research, Xingtao Zhou has published the most significant number of articles, and Shimizu Kimiya had the highest number of citations. The top productive/influential journal was 'Journal of Cataract & Refractive Surgery'. The top cited references primarily focused on reporting the clinical outcomes of implantable collamer lens (ICL) for individuals with moderate to high myopia. The keywords primarily formed four clusters: posterior chamber pIOL clinical outcomes for myopic astigmatism correction, posterior chamber pIOL implantation complications, ICL size selection and postoperative vault predictions, and postoperative visual quality following posterior chamber pIOL implantation. This study presents the first bibliometric analysis of research trends in posterior chamber pIOL over the past two decades. We investigated the current state and emerging trends of global collaboration and research focal points in this field, offering fresh insights and guidance for researchers.

Corneal subbasal nerve plexus reinnervation and stromal cell morphology with different cap thicknesses in small incision lenticule extraction

PurposeThe corneal cap thickness is a vital parameter designed in small incision lenticule extraction (SMILE). The purpose was to investigate the changes in corneal subbasal nerve plexus (SNP) and stromal cells with different cap thicknesses and evaluate the optimized design for the surgery.MethodsIn this prospective, comparative, non-randomized study, a total of 108 eyes of 54 patients who underwent SMILE were allocated into three groups with different corneal cap thicknesses (110 μm, 120 μm or 130 μm group). The SNP and stromal cell morphological changes obtained from in vivo corneal confocal microscopy (IVCCM) along with their refractive outcomes were collected at 1 week, 1 month, 3 months and 6 months postoperatively. One-way analysis of variance (ANOVA) was used to compare the parameters among the three groups.ResultsThe SNPs in the three groups all decreased after surgery and revealed a gradual increasing trend during the 6-month follow-up. The values of the quantitative nerve metrics were significantly lower in the 110 μm group than in the 120 μm and 130 μm groups, especially at 1 week postoperatively. No difference was detected between the 120 μm and 130 μm groups at any time point. Both Langerhans cells and keratocytes were activated after surgery, and the activation was alleviated during the follow-up.ConclusionsThe SMILE surgeries with 110 μm, 120 μm or 130 μm cap thickness design achieved good efficacy, safety, accuracy and stability for moderate to high myopic correction while the thicker corneal cap was more beneficial for corneal nerve regeneration.

POSS and PEG Contained Copolymer for Antibioadhesive Rigid Contact Lenses Materials Application.

Myopia is a global public health issue. Rigid contact lenses (RCLs) are an effective way to correct or control myopia. However, bioadhesion issues remain one of the significant obstacles limiting its clinical application. Although enhancing hydrophilicity through various surface treatments can mitigate this problem, the duration of effectiveness is short-lived and the processing involved is complex and costly. Herein, an antiadhesive RCLs material was designed via 8-armed methacrylate-POSS (8MA-POSS), and poly(ethylene glycol) methacrylate (PEGMA) copolymerization with 3-[tris(trimethylsiloxy)silyl] propyl methacrylate (TRIS). The POSS and PEG segments incorporated P(TRIS-co-PEGMA-co-8MA-POSS) (PTPM) material was obtained and their optical transparency, refractive index, resolution, hardness, surface charge, thermal features, and wettability were tested and optimized. The antibioadhesion activities, including protein, lipid, and bacteria, were evaluated as well. In vitro and in vivo results indicated that the optimized antibioadhesive PTPM materials present good biocompatibility and biosafety. Thus, such POSS and PEG segments containing material were a potential antibioadhesive RCL material option.

Visual Quality Assessment After FS-LASIK Using Customized Aspheric Ablation Profile for Age-Related Accommodation Deficiency Compensation.

To evaluate clinical outcomes and visual quality 12 months after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) performed with the Custom-Q algorithm for correction of myopia with or without astigmatism and compensate for age-related accommodation deficiency. Patients who had Custom-Q FS-LASIK for myopia and myopic astigmatism with age-related accommodation deficiency were included in this retrospective study. Distance, intermediate, and near visual acuities, objective and subjective refractions, Q-factor, corneal higher order aberrations (HOAs), accommodation function, defocus curve, contrast sensitivity, and a subjective questionnaire assessing visual quality were evaluated 12 months postoperatively. Clinical data of 43 cases were analyzed. The mean age was 42.02 ± 1.85 years (range: 40 to 48 years). At the 12-month follow-up visit, there were 43 (100%), 42 (97%), and 33 (77%) patients who achieved a binocular uncorrected distance, intermediate, and near visual acuity, respectively, better than 20/20 separately. Defocus curves revealed better distance vision in the dominant eyes, and the nondominant eyes performed better at intermediate and near vergence (P < .001). The Q-value and corneal spherical aberration coefficient were more positive in the dominant eyes than those in the nondominant eyes (P < .001). The accommodative amplitude and relative accommodation improved binocularly (P < .001). The questionnaire demonstrated high patient satisfaction with near vision, and no one reported having severe visual disturbance. For myopic patients with age-related accommodation deficiency, the Custom-Q algorithm proved to be an effective way to achieve acceptable near vision without compromising distance vision. [J Refract Surg. 2024;40(4):e245-e252.].

Endothelial cell loss post-implantable collamer lens V4c: meta-analysis.

Endothelial cell density (ECD) loss is a noted effect of implantable collamer lens (ICL) V4c surgery. Current literature provides a wide range of values for ECD loss postsurgery, which may not be helpful in advising patients and clinicians. A meta-analysis exploring ECD loss in ICL V4c for myopia correction was undertaken. 18 studies were included in this meta-analysis with 2 subgroup analyses to account for the variability in follow-up lengths. The average ECD loss 3 months, 12 months, and 21.25 (mean) months postsurgery were 1.32% ± 1.28% ( P < .001, 95% CI, -75.158 to -1.19), 1.75% ± 2.17% ( P < .001, 95% CI, -134.09 to 14.52), and 3.84% ± 1.78% ( P < .001, 95% CI, -156.04 to -54.26), respectively. ECD loss is most pronounced 3 months postsurgery, suggesting that acute surgical trauma was the primary contributor rather than long-term lens implantation. Overall, ICL V4c is for myopia correction exhibits similar ECD loss as seen in other ICL models, thereby affirming its safety.

Tissue Saving by Reducing and Using Variable Optic Zone (VOZ) to Correct Myopia by Refractive Lenticule Extraction

Purpose: The lenticular diameter was reduced to below standard 6.5 mm, in a stepwise manner up to 5.2 mm and report on the Residual Stromal Thickness (RST), refractive outcomes and subjective scotopic visual quality of patients compared to those who underwent Small Incision Lenticule Extraction (SMILE) with the conventional 6.5 mm lenticular diameter. Study Design: Retrospective study Methods: Patients undergoing SMILE in the first year of the study were subjected to lenticular diameter of standard 6.5 mm for lenticule extraction. In the second year, using the same nomogram, the lenticular diameter was gradually reduced from 6.4 to 6 mm, with 0.1 mm decrements in each subset. In the last 6 months, all cases were performed using the same nomogram but with lenticular diameter below 6 mm, again with 0.1 mm decrements in each subset. Results: We included 100 eyes of 55 patients with a mean age of 26.18+ 6.6 years (median=25 years, IQR= 22 to 28 years). The mean preoperative best corrected visual acuity (BCVA) was 0.03+ 0.07 logMAR (range = 0 to 0.3 logMAR) and the mean preoperative spherical equivalent was -5.5D + 2.05D (median = -5.5D, IQR= -7.10 to -3.75D). The mean keratometry was 44.12D + 1.3D (range = 41.5 to 48D) and mean central corneal thickness was 532.24+ 29.8 µ (median = 533 µ IQR= 511 to 552 µ, range = 449 to 629 µ). The pupillary size in the study group was 3.80+ 0.82 mm (median= 3.84 mm, IQR= 3.3 to 4.3mm). At 1 month follow up; the best corrected distance visual acuity (UCDVA) across groups was 0.02 + 0.06 logMAR (median = 0 logMAR, range = 0 – 0.3 logMAR). There were no differences in UCDVA and contrast sensitivity between groups with respect to the lenticular diameter. Univariate linear regression analysis showed that age, spherical equivalent, preoperative pachymetry and lenticular diameter size were significantly associated with residual stromal thickness. Conclusion: We found that SMILE performed with a lenticular diameter of &lt; 6 mm was effective in delivering excellent refractive correction and improving the corneal biomechanical strength by virtue of significantly greater RST.

Long-term observation of V4c implantable collamer lenses implantation for moderate to extreme high myopia correction: five years follow-up.

This study aims to assess the long term effectiveness, safety, predictability and stability of V4c implantable collamer lenses (ICL) for correction of moderate to extreme high myopia. We reviewed 125 eyes from 64 patients who implanted V4c ICL at the Refractive Surgery Center of West China Hospital in Chengdu, China, between May 2015 and January 2017. The median spherical equivalent was -11.50 D (interquartile range [IQR]: -13.00 to -9.00 D). We followed up with the patients over five years and evaluated several parameters, including uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), axial length, refractive error, endothelial cell density (ECD), intraocular pressure (IOP), white-to-white distance (WTW), and vault. We performed a correlation analysis to explore the potential impacts on vault following implantation. The median safety index (postoperative CDVA/preoperative CDVA) during the last follow-up was 1.00 (interquartile range [IQR]: 1.00-1.20), and the efficacy indices (postoperative UDVA/preoperative CDVA) were 1.20 (IQR: 1.00-1.25), 1.20 (IQR: 1.00-1.33), and 0.8 (IQR: 0.65-1.00) at postoperative 1 week, 1 month, and 5 years, respectively. At the five-year mark, 16% of the eyes were within ±0.50 D of expected correction, and 73% were within ±2.00 D. No significant difference in ECD was observed between pre-operative and post-operative measurements. Compared to baseline, we observed a significant increase in IOP at the one-week follow-up, which decreased significantly at the one-month visit. Furthermore, we identified ICL size and spherical equivalent (SE) as independent variables in a multiple linear regression model that accurately predicted the five-year vault after surgery. In conclusion, V4c ICL implantation is an effective and safe treatment for moderate to extreme high myopia with good predictability and stability over the long-term.

Современные технологии рефракционной экстракции лентикулы

Purpose. To present modern literature data on the main aspects of refractive lenticular extraction technology. Material and methods. To perform the review, the search for literature sources on PubMed abstract databases was analyzed using the keywords “keratorefractive surgery”, “corneal lenticular”, “femtosecond laser” and data from Russian publications on the topic of the article for the period up to and including 2023. Results. According to the literature data, the strengths and weaknesses of the implementation of each of the existing technologies of keratorefractive surgery have been studied, and the postulates of choosing the optimal method for correcting ametropia have been formulated individually for each patient. Conclusion. Today, keratorefractive surgery is a high-tech industry in ophthalmology and provides a predictable, high-precision and stable refractive result in patients with a wide range of refractive disorders. The analysis of accumulated scientific and clinical experience has shown that one of the most pathogenetically oriented technologies in keratorefractive surgery, minimally affecting the reduction of the biomechanical properties of the cornea, not inducing dry eye syndrome, providing a highly predictable postoperative result in the correction of myopia and myopic astigmatism is refractive lenticular extraction, opening a new era in laser vision correction. Keywords: ametropy, keratorefractive surgery, refractive lenticular extraction

Comparison of Legacy and New No-History IOL Power Calculation Formulas in Postmyopic Laser Vision Correction Eyes

To compare the refractive accuracy of legacy and new no-history formulas in eyes with previous myopic laser vision correction (M-LVC). Retrospective cohort study. Setting: Two academic centers Study Population: 576 eyes (400 patients) with previous M-LVC that underwent cataract surgery between 2019-2023. A SS-OCT biometer was used to obtain biometric measurements, including standard (K), posterior (PK), and total keratometry values (TK). Refractive prediction errors were calculated for 11 no-history formulas: two legacy M-LVC formulas, four new M-LVC formulas using K values only, and five new M-LVC formulas using K with PK or TK. Heteroscedastic testing was used to evaluate relative formula performance, and formulas were ranked by root mean square error (RMSE). New M-LVC formulas performed better than legacy M-LVC formulas. New M-LVC formulas with PK/TK values performed better than versions without PK/TK values. Among new M-LVC formulas with PK/TK values, EVO 2.0-PK was superior to Hoffer QST-PK (P < 0.005). Among new M-LVC formulas using K only, Pearl DGS-K and EVO 2.0-K were both superior to Hoffer QST-K and Barrett True K NH-K formulas (all P < 0.005). Surgeons should favor using new no-history post M-LVC formulas over legacy post M-LVC formulas whenever possible. The top-performing M-LVC formulas (EVO 2.0-PK, Pearl DGS-PK, and Barrett True K-TK) utilized posterior corneal power values. Among formulas utilizing K alone, the EVO 2.0-K and Pearl DGS-K performed best.

Низкоэнергетическая лентикулярная лазерная хирургия в коррекции миопии

Purpose. To improve the efficiency and safety of SMILE-type lenticular surgery procedure in correction of different degrees myopia based on the use of low-energy laser parameters. Material and methods. This study includes a comparative analysis of data from 193 patients (288 eyes) operated for different degrees myopia including a number of cases with myopic astigmatism using SMILE technology with different FSL energy levels from 130 to 150 nJ. The parameters were analyzed on the 1st day and after 1 week, 1 month, 3, 6 and 12 months after surgery with assessment of NCVA, quality of life (QIRC questionnaire), general corneal wavefront aberrations (RMS), densitometry and pachymetry. Results. According to visometry, quality of life assessment, RMS, densitometry and pachymetry, the best functional results were obtained in subgroups with mild and moderate myopia on the 1st day after SMILE using an energy level in the range of 130 nJ. And in subgroups with a high degree of myopia, when using an energy level in the range of 140 nJ, no direct effect of energy on other indicators was found. Conclusion. According to the results of the study, it was found that the correction of myopic refractive error using the SMILE technology with a FSL energy level in the range of 130–140 nJ in its effectiveness on the 1st day after surgery exceeds the previously used energy levels (150 nJ) in terms of the quality of restoration of visual functions and does not have a negative effect on other parameters of the cornea. Key words: myopia, lenticular surgery, femtosecond laser energy, SMILE

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK: a case series.

To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty (SLAK) with corneal crosslinking (CXL) on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis (FS-LASIK). A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo. The lenticules were collected from patients undertaking small incision lenticule extraction (SMILE) for the correction of myopia. Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength. All surgeries were conducted successfully with no significant complications. Their best corrected visual acuity (BCVA) ranged from 0.05 to 0.8-2 before surgery. The pre-operational total corneal thickness ranged from 345-404 µm and maximum keratometry (Kmax) ranged from 50.8 to 86.3. After the combination surgery, both the corneal keratometry (range 55.9 to 92.8) and total corneal thickness (range 413-482 µm) significantly increased. Four out of 5 patients had improvement of corneal biomechanical parameters (reflected by stiffness parameter A1 in Corvis ST). However, 3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze. Despite the onset of corneal edema right after SLAK, the corneal topography and thickness generally stabilized after 3mo. SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia. Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

Retinal complications post posterior chamber phakic intraocular lens implantation at a tertiary eye hospital in the Eastern Province of Saudi Arabia.

Phakic intraocular lenses treat higher degrees of myopia not possible previously with conventional refractive surgery. The aim of this study is to report the incidence and risk factors of retinal complications after posterior chamber PIOL implantation and assess the differences in biometric parameters between patients who developed such complications versus those who did not. This retrospective study recruited 514 patients who underwent ICL implantation to correct myopia at a tertiary eye hospital center in the Eastern province of Saudi Arabia. Follow up period was at least one year. Medical records of the patients were reviewed to obtain the required data. Associations between respondents' characteristics and retinal complications were evaluated using the Chi-squared test. The mean (SD) age was 27.7 (± 6.5) years ranging from 18 to 47. Laser treatment was performed in 14 cases (2.7%). Retinal complications occurred in six cases (1.2%). The risk of retinal complication was significantly higher among patients with high axial length (OR = 1.3, 95% CI 1.2, 1.4) and patients with high pre-spherical equivalent before ICL (OR = 1.09, 95% CI 1.03, 1.4). Patients with higher axial length and higher pre-spherical equivalent before ICL implantation are at high risk of retinal complications.

CORRECTIVE AND PREVENTIVE MEASURES FOR THE PREVENTION OF MYOPIA IN STUDENTS IN A UNIVERSITY ENVIRONMENT

Introduction. The relevance of the conducted research is determined, on the one hand, by the unfavorable epidemiological situation regarding myopia among students, and on the other hand, by extremely incomplete knowledge of the mechanisms that mediate its development, progression, and stabilization.&#x0D; The aim of this study is to carry out a comprehensive analysis of factors that contribute to the development of myopia, as well as the development of methods for assessing the risk of its occurrence, prevention of progression and psychological correction of myopia, research on the role of physical exertion in the prevention of visual fatigue and psychological correction of myopia with the help of therapeutic exercises.&#x0D; Materials and methods. The study covered a representative sample of students from different regions of Ukraine. The number of participants was determined on the basis of statistical calculations to achieve sufficient representativeness of the results – 62 first- and second-year students of the Yuri Kondratyuk Poltava Polytechnic National University. The study of the peculiarities of the stability of attention and the speed of attention switching of myopic and normally ophthalmologically healthy students using the "Correction test" method by B. Burdon.&#x0D; Results and discussion. Analyzing the results of the projective method, we can note that myopic individuals have more often (25%) the influence of the family in their lives, in contrast to healthy individuals (10%). Differences are also observed in the indicators of anxiety, in particular, myopic people show more anxiety in relation to society and feel insecurity (41%), in contrast to healthy people (23%). At the same time, there are insignificant differences in openness to communication – myopic people show a high level (56%) in contrast to healthy people (67%). Among students with a reduced relative reserve of accommodation, a decrease in the static endurance of the back muscles was more often observed. It was 17.74% for boys and 22.58% for girls. 32.25% of boys and 77.41% of girls had incorrect postures. To increase the static endurance of the muscles of the back, neck, and press, a technique was developed that included two repetitions of 2-3 exercises for each muscle group with a short interval between repetitions.&#x0D; Conclusions. 1. Refractive disorders corresponding to mild and moderate myopia include restructuring of function at the level of the retina, visual pathways, and cerebral cortex. 2. Under conditions of the presence of myopia in a person, changes occur in the functioning of both the visual sensory system and higher nervous activity, in particular, attention. 3. The presence of myopia is also related to the psychological characteristics of the individual, in particular, the level of anxiety, the degree of independence and the feeling of attachment to the family, the search for protection from society and a safe environment for self-development. 4. Corrective and preventive measures should include a set of measures, such as psychophysiological stimulation of visual analyzers, selection of individual modes of performance of visual loads, increasing the variety of methods of intra-family interaction. 5. The analysis of the results of the study in the university environment of the impact of physical exercises on the problem of myopia among students showed the high effectiveness of physical activity and adapted physical exercises for the prevention of the development of myopia among students.