The utility of measures of anterior segment parameters of a Pentacam Scheimpflug tomographer in discriminating high myopic astigmatism from keratoconus

The study aimed to evaluate and compare anterior segment parameters between keratoconic eyes and eyes with high myopic astigmatism using Pentacam Scheimpflug tomography. This was a retrospective cross-sectional study that included sixty keratoconic eyes (thirty-two persons) and seventy-three eyes (forty-six persons) with high myopic astigmatism with mean ages 24.72 ± 11.65years and 26.60 ± 10.69years, respectively. Twenty-three parameters from the topographic map and fifteen parameters from the Belin-Ambrosió enhanced ectasia display map of the printouts of a Scheimpflug principle-based Pentacam tomographer were evaluated for their diagnostic accuracy using Receiver Operating Characteristic (ROC) curve. All parameters except cornea volume, anterior chamber volume, and anterior chamber angle indicated a significant difference between high myopic astigmatism and keratoconic eyes. The area under the receiver operating characteristic (AUROC) of eighteen Pentacam parameters was excellent (0.9–1.0) in discriminating keratoconus from high myopic astigmatism, out of which four {anterior minimum sagittal curvature (ant. Rmin), posterior minimum sagittal curvature (post. Rmin), maximum Ambrosió relational thickness (ART max) and total deviation value (D)} indicated excellent (>90%) sensitivity and specificity in addition to the excellent AUROC values. Topographic and Belin-Ambrosió enhanced ectasia display (BAD) maps of a Scheimpflug principle-based Pentacam tomographer are useful in enhancing the diagnosis of keratoconus and may also provide valuable information in effectively screening for keratoconus cases among refractive surgery candidates with high myopic astigmatism.

Vector Analysis of High Astigmatism (≥2.0 Diopters) Correction after Small-Incision Lenticule Extraction with Stringent Head Positioning and Femtosecond Laser-Assisted Laser in Situ Keratomileusis with Compensation of Cyclotorsion

PURPOSE： To compare the astigmatic correction by vector analysis in the high myopic astigmatism between femtosecond laser-assisted laser in situ keratomileusis with compensation of cyclotorsion (FS-LASIK) and small-incision lenticule extraction(SMILE) with stringent head positioning.SETTING: Beijing Aier-Intech Eye Hospital, Beijing, China.DESIGN: Retrospective case series. METHOD: Patients who had correction of myopic astigmatism of 2 diopters (D) or more had either FS-LASIK with compensation of cyclotorsion or SMILE with stringently control the head position were included. Results of vision and refraction were analyzed and compared between groups with the right eye.RESULT: The study enrolled 94 patients (41eye in the FS-LASIK with compensation of cyclotorsion and 53 eyes in SMILE with stringently control the head position). The mean preoperative manifest cylinder was -2.65±0.77D in FS-LASIK and 2.51±0.56D in SMILE group. (P=0.302). At 12-month, there was no significant difference between the two groups in uncorrected distance visual acuity (UDVA, P = 0.274) and postoperative spherical equivalent (P=0.107). 46.3% and 24.5% of eyes were within 0.25D post-op cylinder, 78% and 66% of eyes were within 0.5 D post-op cylinder for FS-LASIK group and SMILE group, respectively (P=0.027, P = 0.202). Vector analysis showed comparable target-induced astigmatism (TIA, P=0.114), surgically induced astigmatism vector (SIA, P=0.057), difference vector (DV, P=0.069) and the angle of error (AE, P=0 .213) between groups. Index of success (IOS) was 0.18 in the FS-LASIK and 0.24 in the SMILE (P=0.024), and significant difference for two groups.CONCLUSION: FS-LASIK with compensation of cyclotorsion had favorable correction in high myopic astigmatism (≥2.0 diopters) compared to SMILE with stringent head positioning at 12-month.

Combining primary and sulcus piggyback IOLs for the correction of a spherical-cylindrical defect in an eye with abnormal cornea

Introduction: Piggyback IntraOcular Lenses (IOLs), or supplementary secondary implant lenses, have been developed to provide a sufficient dioptric power in eyes with high refractive defects, which are not fully correctable after cataract surgery with single IOL in the range of powers available. These lenses can also be used for the correction of refractive errors that occurred for a wrong choice of the IOL power after cataract surgery. Case description: We report the case of a complete refractive success obtained in a patient with an abnormal cornea, with a central stable ectasia, with thinning, high myopic astigmatism and cataract, obtained with the implant of a primary posterior chamber IOL at the time of cataract surgery and a subsequent implant of a secondary piggyback, sulcus-based customized toric IOL (Camellens FIL 622-2 Toric Monofocal IOL, Soleko, Rome, Italy). Conclusions: This brief report demonstrates the utility of combining primary and piggyback IOLs implant for the correction of a complex spherical-cylindrical refractive defect in a case of abnormal cornea and cataract.

Early visual quality outcomes after small-incision lenticule extraction surgery for correcting high myopic astigmatism

Background To evaluate early optical quality outcomes after small-incision lenticule extraction (SMILE) surgery for correcting high myopic astigmatism. Methods This retrospective study enrolled 55 eyes from 37 patients who had preoperative myopic astigmatism of ≥2.00 diopters (D) who had been treated with SMILE surgery. Preoperatively, the mean cylinder was − 2.41 ± 0.54 D (range, − 2.00 D to − 4.50 D). The preoperative and postoperative visual outcomes, refraction, and higher-order aberration (HOA) at 1 and 3 months were compared. Refractive astigmatism changes were analyzed by the Alpins vector method. Results Three months after SMILE surgery, the average cylinder was − 0.14 ± 0.31 D, and the average astigmatism vector was − 0.09 D × 6.34°. The angle of error (AofE) was limited to within ±10°, and the magnitude of error was limited to within ±1.0 D in all patients. The correction index (CI) was 0.98 ± 0.07, the index of success (IOS) was 0.08 ± 0.13, and the flattening index (FI) was 0.97 ± 0.07. Significant positive correlations were found between IOS and |AofE| (P = 0.000); negative correlations were found between FI and |AofE| (P = 0.000). The postoperative total HOA, spherical aberration, vertical coma aberration, and trefoil 30° were increased significantly compared with preoperative measurements, and the increase in HOA was closely related to preoperative astigmatism (P < 0.05). Conclusions SMILE has preferable outcomes for correcting high myopic astigmatism. Axis rotation during the surgery might influence the undercorrection of astigmatism. The increase of HOA after surgery is related to preoperative astigmatism.

Early visual quality outcomes after small-incision lenticule extraction surgery for correcting high myopic astigmatism

Background: To evaluate early optical quality outcomes after small-incision lenticule extraction (SMILE) surgery for correcting high myopic astigmatism.Methods: This retrospective study enrolled 55 eyes from 37 patients who had preoperative myopic astigmatism of ≥2.00 diopters (D) who had been treated with SMILE surgery. Preoperatively, the mean cylinder was -2.41 ± 0.54 D (range, -2.00 D to -4.50 D). The preoperative and postoperative visual outcomes, refraction, and higher-order aberration (HOA) at 1 and 3 months were compared. Refractive astigmatism changes were analyzed by the Alpins vector method.Results: Three months after SMILE surgery, the average cylinder was -0.14 ± 0.31 D, and the average astigmatism vector was -0.09 D × 6.34°. The angle of error (AofE) was limited to within ±10°, and the magnitude of error was limited to within ±1.0 D in all patients. The correction index (CI) was 0.98 ± 0.07, the index of success (IOS) was 0.08 ± 0.13, and the flattening index (FI) was 0.97 ± 0.07. Significant positive correlations were found between IOS and |AofE| (P = 0.000); negative correlations were found between FI and |AofE| (P = 0.000). The postoperative total HOA, spherical aberration, vertical coma aberration, and trefoil 30° were increased significantly compared with preoperative measurements, and the increase in HOA was closely related to preoperative astigmatism (P < 0.05).Conclusions: SMILE has preferable outcomes for correcting high myopic astigmatism. Axis rotation during the surgery might influence the undercorrection of astigmatism. The increase of HOA after surgery is related to preoperative astigmatism.