Simultaneous Topography-guided Custom Ablation With Corneal Cross-linking for Keratoconus: 10-Year Prospective Outcomes

PURPOSE

To assess 10-year visual and tomographic outcomes of topography-guided custom ablation (T-CAT) with corneal cross-linking (CXL) in eyes with keratoconus.

METHODS

T-CAT with CXL was performed in 600 eyes (522 patients). Based on the T-CAT ablation plan, the theoretical maximum ablation depth was 50 µm after epithelium removal. After ablation, accelerated corneal cross-linking (CXL) was performed in the central 8-mm zone (9 mW/cm2 for 10 minutes in "epi-off" mode). The visual acuity and tomography were assessed.

RESULTS

There was significant improvement in uncorrected (P = .001) and corrected (P = .001) distance visual acuity after the procedure. Keratometry, root mean square lower order aberrations and higher order aberrations, defocus, coma 90°, and spherical aberration reduced significantly after surgery at 10 years of follow-up (P < .005). All Pentacam (Oculus Optikgerate GmbH) tomographic variables showed significant changes indicating regularization after T-CAT (P < .005). Flattening of greater than 5.00 diopters in maximum keratometry was noted in 6 eyes (1%). Two of 600 eyes progressed postoperatively and required repeat CXL.

CONCLUSIONS

T-CAT plus CXL is a safe and effective technique even in the long term for regularizing the anterior corneal surface with significant visual improvement and reduction in higher order corneal aberrations. [J Refract Surg. 2023;39(11):759-766.].

Safety and Efficacy of Corneal Minimized-Volume Ablation With Accelerated Cross-Linking in Improving Visual Function for Keratoconus

PURPOSE

To evaluate the safety and efficacy of corneal minimized-volume ablation with accelerated cross-linking in improving visual function in keratoconus eyes.

METHODS

Through a pilot study, 25 eyes of 25 consecutive patients with keratoconus grade I-III were recruited that underwent corneal transepithelial photorefractive keratectomy with "minimized volume" ablation profile and accelerated corneal cross-linking in the same session. Corrected and uncorrected distance visual acuities, manifest refraction, corneal curvature and higher-order aberrations, endothelial cells, and the ocular modulation transfer function were assessed preoperatively and postoperatively, with a minimum follow-up of 6 months. A P value < 0.05 was the threshold of statistical significance.

RESULTS

At 8.2 ± 3.6 months postoperatively, the mean corrected and uncorrected distance visual acuities (LogMAR) were 0.07 ± 0.15 and 0.45 ± 0.39, significantly improving from the baseline of 0.24 ± 0.24 (P8m-before = 0.005) and 1.12 ± 0.33 (P8m-before < 0.001), respectively. Spherical equivalent was -2.80 ± 2.72 diopters (D), significantly decreasing from the baseline of -6.61 ± 3.06 D (P8m-before < 0.001), whereas the attempted corrected spherical equivalent was-2.30 ± 1.22 D. Meanwhile, a significant reduction was found in higher-order aberration, along with the postoperative improvement in ocular modulation transfer function. Corneal surface morphological parameters were found with significant decreases postoperatively (index of surface variance: P8m-before = 0.003; index of vertical asymmetry: P8m-before = 0.005; keratoconus index: P8m-before = 0.004; center keratoconus index: P8m-before = 0.003; and index of height decentration: P8m-before < 0.001). Nevertheless, no significant change was found in posterior corneal curvature or endothelial cell density between pre- and post-operative periods.

CONCLUSIONS

Corneal minimized-volume ablation with accelerated cross-linking was an effective and safe option for correction of mild refractive error, leading to significant improvement of visual function in patients with keratoconus.

Simultaneous Topography-Guided PRK/CXL Versus Topography-Assisted PTK/CXL: 1-Year Prospective Outcomes in Keratoconic Eyes

PURPOSE

To compare 1-year visual and tomographic outcomes of topography-guided photorefractive keratectomy (TGPRK) and topography-assisted phototherapeutic keratectomy (TPTK) with corneal cross-linking (CXL).

METHODS

TGPRK and TPTK were performed in 72 eyes (68 patients) and 74 eyes (71 patients), respectively. Based on the TGPRK ablation plan, the eyes underwent TPTK where the theoretical minimum corneal thickness (MCT) after surgery was less than 400 µm. In the TGPRK group, the theoretical maximum ablation depth was 50 µm after epithelium removal. In TPTK, a decentered single-step PTK was performed only in the steepest anterior curvature zone and the stromal ablation depth was limited to 25 µm. After ablation, accelerated CXL was performed in the central 8-mm zone (9 mW/cm² for 10 minutes in "epithelium-off" mode) in both TGPRK and TPTK. The visual acuity and tomography were assessed.

RESULTS

Improvement in uncorrected (P = .73) and corrected (P = .66) distance visual acuity was similar between the two groups. However, TGPRK eyes had a greater decrease in keratometry, anterior defocus, and spherical aberration (P < .001) at the cost of greater ablation of tissue (P < .001). The median MCT decreased by 27 and 52.5 µm in the TPTK and TGPRK eyes, respectively. Both groups had similar decreases in anterior root mean square of lower (P = .10) and higher (P = .12) order aberrations.

CONCLUSIONS

Both TGPRK and TPTK improved visual acuity in the keratoconic eyes at 1 year of follow-up. However, TPTK removed less volume of tissue. Further, it could be an alternative to TGPRK if the theoretical stromal ablation exceeds 50 µm in thin keratoconic corneas. [J Refract Surg. 2021;37(8):562-569.].

Topography/wavefront-guided photorefractive keratectomy combined with crosslinking for the treatment of keratoconus: preliminary results

PURPOSE

To evaluate the clinical outcomes of topography/wavefront-guided (TWFG) photorefractive keratectomy (PRK) using a new high-definition aberrometer combined with epithelium-off crosslinking (CXL-Plus).

SETTING

Centro Oculistico Bresciano, Brescia, Italy.

DESIGN

Prospective case series study.

METHODS

Patients with grade I or II keratoconus, according to the Amsler-Krumeich classification, were included in this prospective case series. All cases underwent TWFG PRK using the VISX STAR S4 IR excimer laser and the new iDesign 2.0 system, followed by accelerated epithelium-off CXL. Visual, refractive, ocular aberrometric, and safety outcomes were evaluated during a 6-month follow-up.

RESULTS

Thirty-five eyes of 19 patients were included. A significant improvement was observed in the uncorrected and corrected distance visual acuities (P < .001). Manifest sphere and cylinder were reduced significantly (P ≤ .001), with a total of 20 eyes (57%) and 30 eyes (86%) having a postoperative spherical equivalent within ±0.50 and ±1.00 diopter, respectively. Most corneal irregularity indexes and the level of ocular higher-order aberrations, primary coma, and trefoil (P < .05) were significantly reduced postoperatively. No significant corneal haze or safety issues were observed.

CONCLUSIONS

TWFG PRK, using the iD2 system with simultaneous CXL, regularized the cornea by correcting the spherocylindrical error and minimizing the amount of higher-order aberrations in mild-to-moderate keratoconus.

High-Resolution Wavefront-Guided Photorefractive Keratectomy and Accelerated Corneal Crosslinking for Stabilization and Visual Rehabilitation of Keratoconus Eyes

Purpose

To evaluate the visual and refractive outcomes after high-resolution wavefront-guided (HRWG) surface ablation with corneal crosslinking (CXL) in keratoconus eyes.

Patients and Methods

In this prospective, interventional case series, 47 eyes of 28 progressive keratoconus patients older than age 18 were enrolled. All patients underwent HRWG photorefractive keratectomy (PRK) with simultaneous accelerated CXL. The study parameters were manifest refraction spherical equivalent (MRSE), keratometric outcomes, uncorrected (UDVA) and corrected distance visual acuity (CDVA) at postoperative 6 and 12 months.

Results

There was improvement in mean MRSE from -2.39±1.89 D preoperatively to -0.13 ± 0.68 D at 12 months, with corresponding improvement in UDVA from 0.77 ± 0.35 logMAR to 0.08 ± 0.12 logMAR and CDVA from 0.10 ± 0.11 logMAR to 0.02 ± 0.04 logMAR. Preoperative flat and steep keratometry (K) were 4wct 32.49 ± 1.67 D and 45.94 ± 2.10 D, respectively, and at postoperative 12 months were 41.36 ± 2.08 D and 42.65 ± 2.78 D, respectively. At postoperative 12 months, visual and refractive outcomes were maintained. Comparisons between preoperative and postoperative 12 month timepoints were statistically significant for all parameters.

Conclusion

Simultaneous wavefront-guided PRK followed by CXL is a promising treatment for the visual rehabilitation of keratoconus patients.

Non-Orthogonal Refractive Lenses for Non-Orthogonal Astigmatic Eyes

Purpose: To present a novel design method for non-orthogonal lenses to reduce the problem of residual astigmatism in non-orthogonal, astigmatic eyes Methods: A method to create spectacle trial lenses with non-orthogonal power axes was developed based on a novel optimised light ray-tracing algorithm rather than conventional lens design methods which could not fully eliminate spherical aberration. Using this method, three sets of refraction trial lenses were made with the angles between power axes of each set controlled at 80°, 70° and 60°, respectively. Within each set, the cylindrical power varied from -1.00 D to -6.00 D in 1.00 D steps in addition to a -0.50 D lens. Computer-based numerical simulation of the lenses optical performance was carried out to apply orthogonal and non-orthogonal lenses on simulated astigmatic eyes. Subsequently, three clinical trial cases were investigated. Results: Computer-simulated optical performance of non-orthogonal lenses showed the ability to achieve high performance in correcting non-orthogonal astigmatism. Subsequently, three patients with irregular astigmatism were refracted with the non-orthogonal lens sets, and clinically observed improvement at least two lines in the LogMAR chart was achieved in all three cases, compared with correction with orthogonal lenses, along with subjective improvement in image quality. Conclusions: Non-orthogonal astigmatism, which is commonly ignored by current eye prescription systems, is taken into account in this study in the design of spectacle and soft contact lenses. The new approach considers the possible non-orthogonal positions of the eye's two optical power meridians and appears to be better able to correct the vision of irregular astigmatic eyes and significantly reduce residual astigmatism.

High-resolution wavefront-guided surface ablation with corneal cross-linking in ectatic corneas: a pilot study

Purpose

A preliminary study to evaluate the outcomes of high-resolution wavefront-guided (HRWG) photorefractive keratectomy (PRK) with simultaneous corneal cross-linking (CXL) in ectasia eyes.

Methods

Sixteen eyes of 11 patients (mean age 31.9±9.8 years; range: 15–48 years) with keratoconus or post-laser-assisted in situ keratomileusis ectasia underwent HRWG PRK with simultaneous CXL. Manifest refraction, uncorrected (UDVA) and corrected distance visual acuity (CDVA), and keratometric and aberrometric outcomes are reported at 12 months.

Results

Significant improvement was observed postoperatively in visual acuity, refraction, and keratectomy in all eyes. At postoperative 12 months, 87.5% eyes were within ±1.0 D of attempted correction and 81.25% of eyes had a postoperative UDVA of 20/32 or better. A gain of 2 or more lines of CDVA was observed in 12.5% (2/16) of eyes and there was no change in CDVA lines in 25% (4/16) eyes. A substantial reduction in higher-order aberrations was observed in all eyes postoperatively; however, the improvement was not statistically significant.

Conclusion

The outcomes of HRWG PRK in ectasia eyes with estimated residual stromal bed thickness of at least 350 μm (without epithelium) are promising at postoperative 1 year and provide surgeons with a valuable tool to improve vision with a high degree of refractive predictability.

Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

PURPOSE

To evaluate the efficacy and safety of Corneal-Wavefront guided transepithelial photorefractive keratectomy (TransPRK) after corneal collagen cross linking (CXL) in keratoconic patients.

METHODS

In this retrospective, non-comparative, consecutive case series, 39 keratoconic eyes underwent Corneal-Wavefront guided TransPRK for the correction of aberrations at least 4 months after conventional CXL at SEKAL Rovigo Microsurgery Centre, Rovigo, Italy. Two eyes (5%) underwent a secondary laser retreatment for the improvement of post-operative visual acuity and were not included in this retrospective analysis. The mean age of the patients was 35±12 years (19-64 years) at the time of the surgery. Keratron-Scout (Optikon) topographer was used for diagnostic tests and a flying-spot laser (AMARIS; SCHWIND eye-tech-solutions) was used for the refractive surgery. Complete ophthalmic examinations were performed before and after the surgery (4-36 months postoperatively with a mean follow up time of 10±8 months).

RESULTS

Preoperatively, eyes showed irregular astigmatism up to 8D. At last postoperative follow-up, 21 eyes (57%) had UDVA better than 20/40, and six eyes (16%) had UDVA of 20/20. Twenty-three eyes (62%) were within 1.50D of attempted correction in spherical equivalent (mean deviation from target was +1.09±2.36D, range -2.50 to +7.38D). No eye lost 2 Snellen lines of CDVA, and 15 eyes (41%) had an increase of more than 2 lines.

CONCLUSIONS

Corneal-Wavefront guided transepithelial PRK ablation profiles after conventional CXL yields to good visual, optical, and refractive results. These treatments are safe and efficacious for the correction of refracto-therapeutic problems in keratoconic patients.

Visual, aberrometric, photic phenomena, and patient satisfaction after myopic wavefront-guided LASIK using a high-resolution aberrometer

Purpose

The purpose of this study was to evaluate the visual, refractive, and aberrometric outcomes as well as the level of patient satisfaction and photic phenomena after myopic laser in situ keratomileusis (LASIK) surgery using wavefront-guided (WFG) ablations based on measurements obtained with a high-resolution aberrometer.

Patients and methods

This study was a prospective analysis including 253 eyes of 127 patients (aged between 19 years and 54 years) undergoing WFG LASIK using the STAR S4 IR Excimer Laser System combined with the iDesign System and iFS Femtosecond Laser. Visual, refractive, and aberrometric outcomes during a 2-month follow-up as well as patient satisfaction and photic phenomena were evaluated by means of a questionnaire.

Results

A total of 85% (215/253) and 99% (251/253) of eyes achieved a postoperative (Postop) uncorrected distance visual acuity of 20/16 and 20/20, respectively, and all eyes achieved an uncorrected distance visual acuity of 20/25. Postop spherical equivalent values were within ±0.25 D and ±0.50 D in 97% and 100% of eyes, respectively. Likewise, manifest cylinder was <0.25 D in 97% (245/253) of eyes. A statistically significant reduction was found in the total root mean square (P<0.001) and in the level of primary spherical aberration (P=0.001). Postop difficulties related to vision were graded as minimal, with low levels of photic phenomena and high levels of patient satisfaction. The level of difficulty to perform daily activities and the level of glare perceived by patients while driving car were significantly decreased (P<0.001).

Conclusion

WFG LASIK surgery using the technology evaluated is predictable and effective for the correction of myopia and leads to high levels of patient satisfaction.