Thickness of the choroid, ciliary body and retina according to optical coherence tomography in patients after Femto LASIK

Background. In the available literature, there are isolated publications devoted to the topic of the possible effect of laser correction by the Femto LASIK method on the myopic eye choroid. In this connection, in our opinion, the relevance of continuing research in this direction remains.The aim of this study was to examine the volume of the retina in the macular zone, the thickness of the choroid and the ciliary body using optical coherence tomography on myopic eyes after femtosecond-assisted laser in situ keratomileusis in the short term.Material and methods. 30 patients (30 right eyes) aged 20 to 35 years, suffering from mild and moderate myopia, but without pathological changes in the retina according to OCT, made up the study group. All patients underwent myopia correction using the Femto LASIK method. Before the operation, after 4 hours and the next day, they underwent the examination of the retinal volume in the macular zone, the choroidal and the ciliary body thickness using OCTResults. The analysis of the obtained results of the studied parameters showed that the ciliary body thickness and the retinal volume in the macular zone did not undergo statistically signifi cant changes and remained within the preoperative values (p > 0.05). We observed a tendency to an increase in the thickness of the choroid 4 hours after the operation, but the carried out statistical analysis did not confi rm the reliability of its changes (p > 0.05). On the next day, the choroidal thickness indices practically recovered to the preoperative level (p > 0.05).Conclusion. A study of the retinal volume in the macular zone, the thickness of the choroid and ciliary body using OCT in myopic eyes in the short term after Femto LASIK showed the absence of statistically signifi cant changes in the studied parameters, which indirectly indicates the safety of this method of laser correction for the posterior segment of the eye.

Clinical Outcomes of Single-Step Transepithelial Photorefractive Keratectomy and Off-Flap Epipolis-Laser in Situ Keratomileusis in Moderate to High Myopia: 12-Month Follow-Up

Background To compare the quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy (TPRK) and off-flap epipolis-laser in situ keratomileusis (Epi-LASIK) in moderate to high myopia. Methods In this prospective self-control study, we included patients with moderate to high myopia who were randomized to undergo TPRK in one eye and Epi-LASIK in the other eye. Twelve-month follow-up results for visual acuity, refraction, ocular high-order aberrations, contrast sensitivity, postoperative pain, epithelial healing, and haze grade were assessed. Results A total of 64 eyes (32 patients) were enrolled in the study. More eyes completed re-epithelialization in the TPRK group than in the Off-flap Epi-LASIK group 3–4 days postoperatively, while all eyes completed re-epithelialization by seven days. More eyes achieved a visual acuity (both UDVA and CDVA) of better than 20/20 in the TPRK group than in the Off-flap Epi-LASIK group. The ± 0.50 D predictability for correction of the spherical equivalent (SE) was higher in the eyes of the TPRK group (91%) than in those of the off-flap Epi-LASIK group (80%) 12 months after surgery. No significant differences in ocular aberrations, including coma, spherical, and trefoil, were found between the two groups at 12 months. There were also no significant differences in visual acuity, contrast sensitivity, pain, and haze grading between the two groups. Conclusions Both TPRK and off-flap Epi-LASIK are safe, effective, and predictable treatments for moderate to high myopia with comparable surgical outcomes. Trial registration: This study was retrospectively registered on ClinicalTrial.gov (NCT05060094, 17/09/2021).

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Background: Many studies have used functional optical zone (FOZ) as a measure to compare different refractive laser treatment modalities. However, to our knowledge, no study has compared wavefrontoptimized (WFO) and wavefront-guided (WFG) laser in situ keratomileusis (LASIK) using FOZ. We compared the FOZ after WFO versus WFG LASIK in patients with myopia and myopic astigmatism.Methods: In this prospective comparative study, we included 100 myopic eyes of 50 patients with or without astigmatism. They were divided into two groups according to the platform used: WFO or WFG femtosecond LASIK. Using Holladay’s equivalent keratometry reading (EKR) report of Pentacam HR, FOZ was defined as a zone centered on the pupil center with a standard deviation (SD) of 0.5 D, around the mean EKR. The differences in FOZ between the two platforms were analyzed at 3 months postoperatively. Visual acuity, refractive error, corneal asphericity (Q-value), and root mean square of higher-order aberrations (RMS for HOAs) were evaluated and compared.Results: The mean ± SD of patient age was 26.64 ± 5.67 years. The preoperative characteristics of the two groups were comparable (all P > 0.05). The intended optical zone (IOZ) was 6 mm in both groups. The mean laser ablation depth was significantly greater in the WFG group (18 ?m per D) than in the WFO group (16 ?m per D) (P = 0.035). At 3 months postoperatively, the mean ± SD of FOZ diameter was 4.32 ± 0.94 mm (71.99 ± 15.68% of intended optical zone) in the WFO group and 4.16 ± 1.13 mm (69.33 ± 18.78% of intended optical zone) in the WFG group, with no significant difference between the two groups (P = 0.622). The change in corneal asphericity was greater in the WFG group than in the WFO group (P = 0.034). Postoperative mean corrected and uncorrected distance visual acuity, manifest refraction, and RMS for HOAs showed no significant difference between the two groups (all P > 0.05).Conclusions: We found that WFG LASIK resulted in greater ablation depth and change in corneal asphericity than WFO LASIK at 3 months postoperatively. However, there was no significant difference in FOZ diameter, refractive error, and RMS for HOAs between the two groups. Further research is needed to confirm these findings.

Comparison between the change in total corneal astigmatism and actual change in refractive astigmatism in transepithelial photorefractive keratectomy (tPRK), laser in situ keratomileusis (LASIK) and femtosecond laser assisted laser in situ keratomileusis (FsLASIK)

Purpose To compare changes in astigmatism by refraction and total corneal astigmatism after tPRK, LASIK and FsLASIK. Setting Specialty Eye Hospital Svjetlost, Zagreb, Croatia. Design Partially masked, semi-randomized, prospective, case-by-case, interventional, clinical study. Methods Patients with a stable refraction (-0.75DS to −8.00DS, astigmatism ≤1.00DC) underwent tPRK, LASIK or FsLASIK without complication. Astigmatism was measured at both corneal surfaces over the central 3.2 mm zone (approximately using Pentacam HRTM) preoperatively and 3 months postoperatively. Pentacam and refraction data were subjected to vector analysis to calculate the surgically induced changes in i) total corneal astigmatism (SIATCA) ii) any astigmatism by refraction (SIAR) and the vectorial difference (DV) between SIATCA and SIAR. Results Reporting key findings (p < .01), there was a significant difference between mean SIATCA and SIAR powers after tPRK (75eyes) but not after LASIK (100eyes) or FsLASIK (100eyes). Mean (±sd,95% CIs) values for DV powers were, tPRK −1.13DC(±0.71, −1.29 to −0.97), LASIK −0.39DC(±0.23,-0.44 to −0.34), FsLASIK −0.55DC(±0.38,-0.62 to −0.47). The differences were significant. For the tPRK and FsLASIK cases, linear regression revealed significant associations between I) SIATCA (x) &DV (z) powers (tPRK z = 1.586x-0.179, r = 0.767, p < .01; FsLASIK z = 0.442x-0.303, r = .484,p < .01), II) sines of SIATCA (x1) &DV (z1) axes (tPRK, z1 = 0.523 × 1 + 0.394, r = .650,p < .01; FsLASIK z1 = 0.460 × 1-0.308, r = .465,p < .01). Conclusions tPRK is more prone to unintended changes in astigmatism. The difference between SIATCA & SIAR after tPRK or FsLASIK is mediated by SIATCA. Photoablating deeper regions of the cornea reduces the gap between SIATCA & SIAR.

Comparison of Objective and Subjective Visual Quality Following LASEK, FS-LASIK and SMILE for Different Myopic Corrections: A Prospective Study

Background: To investigate the differences in visual quality after laser epithelial keratomileusis (LASEK), femtosecond laser in situ keratomileusis (FS-LASIK) and small-incision lenticule extraction (SMILE) in different degrees of myopia.Methods: This prospective study incorporated 200 consecutive myopic subjects (200 eyes). Myopia was subdivided into 3 levels based on the preoperative spherical equivalent (SE) value: low myopia (SE ≥ -3.0 D), moderate myopia (−3.0 D > SE ≥ −6.0 D), and high myopia (SE < −6.0 D). Visual quality was recorded and analyzed both objectively using the Optical Quality Analysis System II (OQAS II), and subjectively with uncorrected distance visual acuity (UDVA) and a questionnaire, preoperatively, 1 month and 6 months postoperatively. Results: Six months after LASEK, FS-LASIK and SMILE in myopia, the logarithm of the minimum angle of resolution (LogMAR) UDVA statistically decreased compared with preoperative values (all P < 0.001). While preoperatively, in three surgical procedure groups, objective visual quality parameters demonstrated no significant difference among three degrees of myopia (all P > 0.05), at 6 months postoperatively, after FS-LASIK and SMILE, the modulation transfer function (MTF) cutoff frequency in low myopia was significantly higher than that in high myopia (both P < 0.05). Moreover, intergroup differences in LASEK, FS-LASIK and SMILE groups were not statistically significant, before and 6 months after surgery (all P > 0.05), except that FS-LASIK provided a significantly higher preoperative LogMAR UDVA than SMILE in high myopia (P < 0.05).Conclusion: LASEK, FS-LASIK and SMILE could achieve similar improvement in visual quality to each other after myopia correction. Low myopic patients may achieve better postoperative visual quality after FS-LASIK and SMILE than high myopic patients.Trial registration: This is a prospective study. The study followed the Declaration of Helsinki and was approved by the Institutional Review Board of the Second People’s Hospital of Yunnan Province.

Scheimpflug Topography Oriented Adequate Repositioning of a Misaligned Free Flap after Laser in situ Keratomileusis

This report describes a case of Scheimpflug topography oriented adequate repositioning of a misaligned thick free flap after laser in situ keratomileusis (LASIK). A 24-year-old patient consulted for irregular astigmatism and disoriented free right eye flap. The patient previously underwent binocular LASIK at a private clinic. During the right eye surgery, the flap was repositioned after laser ablation due to the free flap. The free flap was not repositioned to its original configuration due to insufficient preoperative corneal marking. On examination, the uncorrected visual acuity was 0.4, and refractive power was +2.00 Dsph with −4.25 Dcyl axis 66 in the right eye. Scheimpflug topography revealed irregular right eye astigmatism. The sagittal curvature of topography showed a 40° counterclockwise misalignment of the steep axis of the cornea. The free flap was repositioned by 40° clockwise rotation. After this, the refractive corneal power improved to −1.00 Dsph with −1.00 Dcyl Axis 19 in the right eye. The uncorrected and best-corrected visual acuity improved to 20/30 and 20/25 (x − 0.25Dsph −1.25 Dcyl A20), respectively. This is the first report on free flap repositioning using Scheimpflug topography. As proper flap positioning was compromised because of the free LASIK flap with no preoperative corneal marking, the flap was effectively repositioned using Scheimpflug topography.