Postoperative Corneal Higher-order Aberrations Research Articles

Long Term Evaluation of Surgically Induced Astigmatism and Corneal Higher-Order Aberrations After 2.2 Mm Clear Corneal Incisions in Femtosecond Laser-Assisted Cataract Surgery: Temporal versus Superior Approach.

To assess long term changes of the surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs) after 2.2 mm clear corneal incisions (CCIs) in femtosecond laser-assisted cataract surgery and compare them between 2 types of CCIs: temporal and superior approach. Patients received the temporal CCIs (Group A) or the superior CCIs (Group B). Outcome measures included visual acuity, manifest refraction, corneal astigmatism, SIA, flattening effect, and corneal HOAs. Correlation between postoperative corneal HOA and SIA at each follow-up were analysed. This study assessed data from 106 eyes, of which 64 in Group A and 42 in Group B. The two groups had similar postoperative visual acuity of distance, intermediate and near (all P > 0.05). SIA and corneal HOAs were significantly lower in Group A than Group B in the early postoperative period, while there was no significant difference in the late postoperative period. At 6 months after surgery, the arithmetic mean of SIA over corneal 4mm zone was 0.33 ± 0.19D for temporal incision, and 0.37 ± 0.25D for superior incision. For Group A, the correlations of HOAs and SIA persisted from 1 week to 6 months after surgery. For Group B, the changes in corneal HOAs were significantly related to the SIA at 1 week and 1 month postoperatively. This study suggested the consistency of increasing and recovering process of corneal HOAs and SIA after surgery. Compared to the superior incisions, temporal incisions might induce quicker corneal recovery and less change in SIA and corneal HOAs.

Hyperopia-Correcting Phototherapeutic Keratectomy and Its Comparison With Conventional Phototherapeutic Keratectomy

PurposeTo evaluate hyperopia-correcting phototherapeutic keratectomy (HC-PTK) and to compare the visual and refractive outcomes of HC-PTK and conventional PTK.MethodsThis study comprised a total of 72 eyes of 72 consecutive patients who underwent HC-PTK and conventional PTK for granular corneal dystrophy or band-shaped keratopathy. Preoperatively and 6 months postoperatively, we assessed visual acuity, manifest refraction, and mean keratometry, as well as postoperative corneal higher-order aberrations and adverse events in each PTK group, and compared these metrics between the two groups.ResultsLogMAR BSCVA significantly improved from 0.43 ± 0.47 preoperatively to 0.21 ± 0.38 postoperatively in the HC-PTK group (Wilcoxon signed-rank test, p < 0.001). It was also significantly improved from 0.22 ± 0.21 preoperatively to 0.15 ± 0.12 postoperatively in the conventional PTK group (p = 0.031). Mean refraction significantly changed from 0.27 ± 1.55 diopter (D) preoperatively to 0.50 ± 1.77 D postoperatively, in the HC-PTK group (p = 0.313). By contrast, it was significantly hyperopic from −0.15 ± 2.41 D preoperatively to 1.45 ± 2.46 D postoperatively, in the conventional PTK group (p < 0.001). No significant complications occurred in any case during the follow-up period.ConclusionBoth HC-PTK and conventional PTK showed a significant improvement of BSCVA and no vision-threatening complications at any time in this series. HC-PTK significantly reduced a hyperopic shift in refraction compared with conventional PTK, suggesting its viability for patients requiring PTK, especially in consideration of preventing this hyperopic issue.

Effects of SMILE and FS-LASIK on early postoperative corneal higher order aberrations in patients with high myopia

Effects of SMILE and FS-LASIK on early postoperative corneal higher order aberrations in patients with high myopia

Corneal Biomechanical Changes After Intracorneal Ring Segment Implantation in Keratoconus

To evaluate by means of the Ocular Response Analyzer (ORA) the biomechanical changes that follow intracorneal ring segment (ICRS) implantation and to develop a predicting model for the postoperative visual outcome, considering these biomechanical changes and other clinical parameters. A total of 45 consecutive keratoconic eyes of 35 patients aged 18 to 55 years and implanted with ICRS were included in this retrospective study. All patients were implanted with KeraRing using femtosecond laser technology. Visual acuity, refraction, corneal topography, and aberrations were evaluated during a 6-month follow-up. Additionally, corneal biomechanical changes were evaluated with the ORA system. No significant changes in corneal hysteresis (CH) and corneal resistance factor (CRF) were observed at 1 month postoperatively (P ≥ 0.39). However, significant changes in these parameters were detected afterward (CH, 3 months, P = 0.03; CRF, 6 months, P = 0.02). Preoperative corneal biomechanical parameters were significantly correlated with postoperative corneal higher-order aberrations at all visits (P ≤ 0.05), although these correlations became stronger at the end of the follow-up. Multiple regression analysis revealed that corrected distance visual acuity at 1 month after surgery was significantly correlated with the preoperative mean keratometry and the preoperative difference between CH and CRF (P < 0.01, adjusted R² of 0.66). Biomechanical parameters measured with the ORA and mean keratometry are factors allowing a prediction of the postoperative visual outcome in a short term after ICRS implantation in keratoconic eyes. In the long term, corneal biomechanical changes limit the prediction of the ring segment effect.

Intraindividual Comparison of Functional Vision and Higher Order Aberrations After Implantation of Aspheric and Spherical Intraocular Lenses

To compare the intraindividual effects of an aspheric intraocular lens (IOL) (Tecnis Z9000, Advanced Medical Optics Inc [AMO]) with a conventional spherical IOL (AcrySof single-piece SA60AT, Alcon Laboratories Inc) on functional vision and higher order aberration. In this prospective study, 40 eyes of 20 patients presenting for cataract surgery were randomly assigned to receive a spherical IOL (AcrySof one-piece) in one eye and an aspheric IOL (Tecnis) in the contralateral eye. Patients were followed for 3 months postoperatively. The results of sine-wave grating contrast sensitivity, contrast acuity under mesopic and photopic conditions, and higher order aberrations (3rd, 4th, and 5th order, primary spherical and total) root-mean-square (RMS) were compared intraindividually. The postoperative corneal higher order aberrations were not significantly different between the two IOL groups. Total higher order aberrations, total 4th order, and primary spherical aberrations were significantly lower in the Tecnis group at pupil size > 5 mm. Contrast acuity was not significantly different between the two IOL groups under mesopic and photopic conditions. Mean pupil size under mesopic conditions was 4.20 mm and 4.08 mm in the AcrySof and Tecnis groups, respectively. Sine-wave contrast sensitivity test results were slightly better in the Tecnis group at spatial frequencies of 1.5, 3, 6, and 12 cycles per degree, but these differences did not reach statistical significance. Compared to conventional spherical IOL, the Tecnis aspheric IOL significantly reduced total ocular and spherical aberration but did not result in better functional vision under mesopic or photopic conditions. Small pupil size may be a factor, which limits the beneficial effect of aspheric IOLs on visual performance.