SPS-206 Keratoconus: Treatment Comparisons and Outcomes | ASCRS
2020 ASCRS Virtual Annual Meeting

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Papers in this Session
Expand each tab below to view the paper abstract for each paper within this session.
Treatment of Keratoconus with Topographic Guided Excimer Laser Ablation and Corneal Cross Linking.
Author
Manoj V. Motwani, MD

Purpose
Demonstrate the results of treatment of Keratoconus by topographic guided ablation and corneal cross linking on 40 eyes.

Methods
40 eyes with at least 3 months follow-up were analyzed retrospectively after topographic guided ablation utilizing the Wavelight EX500 Contoura system followed by corneal cross linking utilizing a 15 minute protocol and 0.1% riboflavin solution. All procedures were performed by one surgeon in one center, and post-operative results were evaluated for vision, refraction, potential vision gained, and corneal steepness reduction.

Results
All eyes had reduction of corneal steepness, and did not display keratoconus progression after the procedure. All eyes had improvement of refraction, most eyes had improvement of best corrected visual acuity. Further evaluation of the data is currently ongoing and will be ready for presentation.

Conclusion
Treatment of keratoconus with Contoura and CXL was effective and safe, decreased corneal steepness and stabilized keratoconus progression. No eyes had loss of BCVA, and most had improvement of vision, refraction, and BCVA.
Comparing Keratoconus and Post-LASIK Ectasiaprogression Rate after Corneal Collagen Cross-Linking: 3 Years Follow up
Author
Elias F. Jarade, MD

Purpose
To report and compare the rate of ectasia progression between patients with keratoconus and post-LASIK ectasia over 3 years post collagen crosslinking(CXL)

Methods
METHODS: retrospective cohort study of patients undergoing CXL for either keratoconus or post-LASIKectasia(referred as‘’ectasia’’). Corrected distance Visual acuities(CDVA), manifest refraction, keratometry(K) and pachymetry were followed over 3 years

Results
RESULTS:54 eyes with ectasia and 111 eyes with keratoconus were included in the study. 12 of 54 eyes with ectasia (22.2%) and 4 of 111 eyes (3.6%) with keratoconus had progression post CXL (p-value:0.0001). Ectasia patients who progressed were older at presentation (36.1 vs 31 years)(p-value: 0.02) than stable ones, and older than keratoconus patients. In keratoconus, CDVA, SE, sphere, cylinder and K-mean improved significantly at 3 years post-CXL (p-value<0.05), but,these values improved without reaching a statistical significance in post-LASIK ectasia patients

Conclusion
Eyes with post- LASIK ectasia seems to be less responsive to crosslinking than keratoconus.
Evaluation of Corneal Topography and Tomography in Fellow Eyes of Unilateral Keratoconus for EARLY Detection of Subclinical Keratoconus
Authors
Mithun Thulasidas, MD
Prateek Teotia, MS

Methods
This five-year retrospective comparative case series included 15 advanced keratoconus eyes of unilateral KCN (KCN group), 15 normal fellow eyes of unilateral KCN (Fellow eye group) and 34 eyes of normal refractive surgery candidates (Normal group). Topographic and tomographic data, data from enhanced elevation maps and keratoconus indices were measured in all study eyes using Pentacam. Receiver operating characteristic (ROC) curves were used to evaluate the area under curve (AUC), sensitivity, and specificity of each parameter and identify cut-off points in discriminating between fellow and normal eyes.

Results
Corneal thickness at the thinnest point (CTT) and at the apex (CTA), Belin/Ambrosio Enhanced Ectasia Display (BAD) - Dt (thinnest point), Da (thinnest point displacement) and corneal volume were statistically significantly lower in fellow group compared to eyes of normal subjects (P<.05). On ROC curve analysis, the most efficient distinguishing indices between the fellow group and the normal controls were BAD - overall D value (AUC=0.859), Dt (AUC=0.827), Da (AUC=0.789) followed by Progression Index (PI), maximum elevation on posterior/anterior cornea surfaces and keratometric asymmetry.

Conclusion
BAD D value, PI, posterior/anterior elevation and keratometric asymmetry may be useful in detecting the earliest form of subclinical KCN. However, each single parameter alone is not sufficient to detect early changes; combination of different data is required to distinguish subclinical keratoconus.
Corneal Haze after Cross-Linking for Keratoconus Eyes with and without Mitomycin C Application
Authors
Shady T. Awwad, MD
Lily Chacra, MD
Chadi Helwe, MSc
Farhad Hafezi, MD, PhD
Emilio A. Torres Netto, MD

Purpose
To evaluate corneal haze as determined by OCT after cross-linking as compared to cross-linking with Mitomycin C application for the treatment of mild to moderate Keratoconus.

Methods
A retrospective analysis of 87 myopic eyes of 72 patients with mild to moderate keratoconus. The first group (n=43 eyes) underwent cross-linking with mitomycin C between March 2015 & December 2015, and the second group (n=44 eyes) underwent cross-linking without mitomycin C between June 2013 & February 2015, both following the Dresden Protocol. Patients were evaluated preoperatively and at 1, 3, 6 and 12 months postoperatively. Main outcome measures were haze intensity, size and location as measured by a dedicated OCT image analysis software.

Results
Anterior stromal haze area at 1 month was 51.83±17.96% and 31.33±19.85% for the MMC and conventional group, respectively (p<0.001), and 49.86±16.97% and 37.54±19.18% (p<0.04) at 3 months. Anterior haze average brightness at 1 month was 70.67±9.31 and 59.52±5.12 (p<0.01) for the MMC and conventional, and 66.24±13.64 and 60.37±5.68 (p<0.04) at 3 months. The MMC UDVA and CDVA LogMar were 0.37±0.34 and 0.20±0.20 preoperatively and 0.38±0.37 and 0.20±0.13 at 1 year. For the conventional group they were 0.35±0.31 and 0.22±0.22, and 0.27± 0.18 and 0.14±0.12. The CXL/MMC Kmax was 53.42±6.88 preoperatively and 49.44±5.67 postoperatively, compared to 52.27±5.78 and 50.91±4.25 for the CXL (p<0.008).

Conclusion
Mitomycin C application following cross-linking increases corneal haze. Similar studies need to be performed on simultaneous cross-linking and PRK procedures to evaluate MMC role in haze formation.
Comparative Evaluation of Corneal Tomography Symmetry Based on Centration:Vertex Versus Geometric Center of the Cornea
Authors
Shady T. Awwad, MD
Madeleine Y. Yehia, MD
Lara F. Asroui, MD

Purpose
To evaluate corneal symmetry output when tomography measurements are centered on the vertex versus the geometric center of the cornea

Methods
138 eyes of 138 patients were measured: 94 eyes myopic and 44 hyperopic eyes. Vertex-based measurements were performed first, then the measurements were decentered to the geometric center of the cornea (GCC) after removing the automatic centration option of the Galilei dual placido and Scheimpflug system. Primary outcome measure included the posterior best fit sphere elevation data, with area under the curve (AUC) of the temporal elevation data point subtracted from the nasal one to evaluate horizontal symmetry and superior minus inferior one for vertical symmetry.

Results
The angle alpha chord magnitude and angle were in myopes were 0.37±0.14 mm horizontally and 0.09±0.08 mm vertically (vector magnitude: 0.39±0.14 mm. In hyperopes, it was 0.55±0.41 mm vertically and 0.15±0.19 mm horizontally (vector magnitude of 0.52± 0.12 mm). With vertex centration, the absolute difference in AUC for the horizontal BFS elevation data was 1.31±0.96 μm², compared to 0.52± 0.43 μm² for GCC centration (P<0.01), while for the vertical BFS elevation, it was 1.12 ±0.88 μm² vs. 1.29± 0.92 μm² (P>0.05). For myopes, the horizontal AUC was 0.72± 0.87 μm² with vertex vs. 0.49± 0.36 μm² with GCC (P<0.05), and the vertical AUC was 0.49± 0.42 μm² vs. 0.51± 0.37 μm² (P>0.05).

Conclusion
Tomography measurements based on the geometric center of the cornea display much more symmetry and a more natural cornea than the vertex-centered ones, notably horizontally, in agreement with angle alpha offset which is often much more pronounced nasally than vertically.
A Comparison of CXL Combined with Epithelial PRK (CXL-ePRK), Topography Guided PRK (CXL-TGPRK) and Intrastromal Ring Segments (CXL-ICRS)
Authors
Michael Mimouni, MD
Wendy V Hatch, OD, MSc
Raymond M. Stein, MD
Igor Kaiserman, MD
Neera Singal, FRCS, MD

Purpose
Several procedures combine crosslinking (CXL) with additional modalities in order to improve refractive outcomes in patients with progressive keratoconus. The purpose of the current study was to compare visual outcomes after CXL combined with epithelial PRK (CXL-ePRK), topography guided PRK (CXL-TGPRK) and intrastromal ring segments (CXL-ICRS).

Methods
A post-hoc analysis of consecutive progressive keratoconus patients that underwent CXL-TGPRK or CXL-ICRS or CXL-ePRK between 2014 to 2017 at one of three private centers. In order to account for potential differences in baseline parameters between groups matching of baseline characteristics will be performed. The primary outcome measures will be a comparison of change in uncorrected and corrected distance visual acuity following each of the procedures. Secondary outcome measures will be change in: keratometry values, pachymetry, refractive error, higher order aberrations and the occurrence of complications such as haze.

Results
93 CXL-TGPRK and 50 CXL-ePRK were included. There were significant differences between groups in terms of baseline age, UDVA, refractive error, BSCVA and CCT (p<0.05 for all). Both groups significantly improved in terms of UDVA, refractive error and BSCVA with a decrease in CCT (p<0.05 for all). When comparing adjusted (for baseline) postoperative outcomes between groups, CXL-ePRK was superior (mean difference) for postoperative UDVA (0.44±0.11 logMAR, p<0.001), spherical equivalent (1.73±0.87D, p=0.05), sphere (2.51±0.92D, p=0.007), cylinder (1.57±0.63D, p=0.01) and efficacy index (0.47±0.14, p=0.001). There were no significant differences in adjusted postoperative CCT (p=0.87).

Conclusion
Both CXL-ePRK and CXL-TGPRK provide improved uncorrected and corrected vision for keratoconus patients while stabilizing keratometry indices at the expense of a decreased CCT. It seems as though CXL-ePRK may offer superior uncorrected visual acuity by reducing the amount of myopia and cylinder at a greater magnitude than CXL-TGPRK.
Pupillary Zone Sparing Partial Corneal Epithelium Debridement for C3R in Eyes with Thin Cornea and Post-Lasik Keratectasia in Keratoconus.
Authors
Tushya O. Parkash, MS
Ajay Khanna, MS
Rohit Om Parkash, MS
Shruti Mahajan, MS

Purpose
To evaluate the outcome of pupillary zone sparing partial corneal epithelium debridement for collagen cross linking in eyes with thin cornea and post-lasik keratectasia(PLK)in Keratoconus.

Methods
Retrospective study was done in 10 eyes of PLK and 32 eyes of thin cornea(Thinnest CT-380 to 400 microns) undergoing standard conventional C3R from Feb 2012-Jan 2018.After instilling anesthetic eye drops,epithelium was mechanically debrided in vertical full thickness stripes,1.5-2 mm wide with 1mm distance between them with a blunt hockey stick knife.Flap margin area in eyes with post Lasik Keratectasia was avoided from debridement. Approximately central 2-3 mm zone corresponding to the pupillary axis and thinnest point was spared from debridement.Dresden protocol for C3R was followed.Visual,keratometric & haze outcomes were evaluated using Pentacam HR at an interval of 3,6,12 & 18 months.

Results
In the immediate post-operative period, pupillary zone showed minimal haze as compared to the rest of the cornea from where epithelium was debrided. A well demarcated line was also observed 4-8 weeks post operatively.Wong Baker(WB)pain score was 2.84+0.8 on POD 1 which reduced over 2 days.Mean spherical and cylindrical error were reduced but weren't statistically significant. Flat and steep keratometry, were significantly reduced (p<0.001) and remained stable over a follow up of 18 months. Postoperatively haze(corneal densitometry)in the central 0–2 mm zone was 16.35 ± 3.54 GSU and in the 2–6 mm zone was 13.57 ±2.46 GSU at 3 months, which was statistically insignificant.

Conclusion
Pupillary zone sparing partial corneal epithelium debridement for C3R using Dresden protocol in eyes with thin cornea and post-lasik keratectasia causes minimal haze in the pupillary zone without compromising good outcomes
A Randomized Clinical Trial Study of Laser Versus Mechanical Intrastromal Corneal Ring Segment Implantation in Keratoconus (No Audio)
Author
Hamidreza Hasani, MD, MSc

Purpose
To compare visual, refractive, and corneal aberrometric outcomes and complications of mechanical and and femtosecond laser-assisted tunnel creation for intrastromal corneal ring segments (ICRS) in keratoconic eyes.

Methods
56 keratoconic patients were randomly assigned to have ICRS tunnel creation by a mechanical device or a femtosecond laser. Keraring with a 0.5 mm diameter and different degree arc length were implanted. All patients had contact lens intolerance and clear central corneas with moderate to severe keratoconus. A complete ophthalmic examination, including uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), manifest refraction, keratometric readings (orbscan II), ultrasound pachymetry, slit lamp examination were performed before and after surgery. All 3, 6, and 12-month follow-ups were completed and the data was compared in two groups statistically.

Results
One year postoperatively, significant improvement was observed regarding the mean UCDVA and CDVA (both p<.001). Keratometry readings, SE, and manifest sphere improved in both groups at 3, 6, and 12 months (p<.001). The mean reduction in maximum keratometry was 6.38 diopters (D) in mechanical group and 7.04 D in femtosecond laser group. The mean reduction in SE was 4.17 D and 5.47 D, respectively. There was significant improvement in cylinder in femtosecond laser group at 12 months and in mechanical group at 3,6, and 12 months. The reduction in cylinder was significantly greater in femtosecond laser group at 6 months (p=.027). There was no statistically significant difference between the two groups in visual or refractive results (p>.05). Bacterial keratitis, superficial segment placement, and segment extrusion in 1 eye, and white sterile deposition in 5 eyes occurred in the mechanical group.

Conclusion
Similar visual and refractive outcomes were achieved by implanting a ICRS using mechanical and femtosecond laser assisted procedures, despite more intraoperative complications in mechanical group.

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