A 21-year-old patient presented in August 2026 with keratoconus. The patient has a history of epithelial-on cross-linking that was performed in 2019, and again in 2023. The patient has noted progressive worsening of vision over the past year. This patient had epithelial compensation adjusted transepithelial topography-guided ablation performed with sequential corneal cross-linking (CXL) to treat the corneal ectasia. To demonstrate the rapidity of corneal topography, epithelial compensation, and visual acuity changes that occur, 2-week results are reported here. Over time and with healing, the refractive error and visual acuity will actually improve.
Materials and Methods
The patient was examined with multiple imaging modalities to confirm diagnosis, determine the extent of ectasia, and for surgical planning to reduce corneal irregularity. Pre-op and 2-week post-op imaging is reported. The patient was then treated with the CREATE+CXL protocol, which consists of three procedures:
An epithelial compensation adjusted transepithelial phototherapeutic keratectomy (PTK).
Topography-guided photorefractive keratectomy (PRK) with the WaveLight EX500 Contoura system (Alcon).
Sequential epithelial off cross-linking.
Corneal topography was performed with the Wavelight Topolyzer Vario (Alcon) and the Optovue Solix (Visionix).
Results
Thinnest epithelial thickness in central 5mm: 43 µm
Thickest epithelial thickness in central 5mm: 65 µm
Pre-op Rx and best-corrected visual acuity (BCVA): +0.50, -0.50 x 75 20/60
Post-op Rx and BCVA: +1.00, -1.00 x 5 20/20
Pre-op Kmax: 47.8
Post-op Kmax: 43.6
Discussion
Keratoconus and corneal ectasia diagnosis are normally performed by topography and scheimpflug imaging looking at the posterior elevation of the cornea. As ectasia advances further, different modalities can be used to determine the extent of the keratoconus.
In Figure 1, the pre-op anterior topography demonstrates a severe keratoconus cone. The pre-op Optovue Solix OCT (Figure 2) epithelial thickness map shows a thin area of epithelium over the cone and thickening of epithelium around the bottom of the cone. This is very diagnostic of corneal ectasia, as the epithelium thins over the steepest aspect of the cone, and thickens around the base of the cone to attempt to decrease the irregularity. This prevents the topography system from measuring the full extent and shape of the cone. If the topography-guided ablation simply followed the anterior topography, a residual “mini” cone would be left behind that the epithelium compensation had masked from anterior topography imaging.
Figure 1: Pre-op (left) and post-op (right) topography images taken with Alcon Topolyzer Vario.
Note that as the epithelium is healing in the postoperative Optovue Solix OCT map, it is no longer thickening or thinning in the areas where the cone was reduced. The best-corrected vision is dramatically improved even with the short healing time of only 2 weeks, demonstrating how rapidly vision, imaging, and even epithelial compensation changes can be noted after reduction of corneal anterior stromal irregularity.
Figure 3 shows the topography-guided ablation reduction of higher-order aberrations (HOA), with the laser treatment split between the flattening of the paracentral cone to “flatten” it, and peripheral treatment of the superior flat area to effectively “raise” it. Total aberration in the central 5 mm would be the amount of epithelial compensation (21 µm total, 15 µm over the central cone) plus the amount measured by topography (31 µm). This results in 32% of the central aberration being masked to topography and therefore not treated with topography-guided PRK alone for this patient.
Figure 3: WaveLight Contoura higher-order aberrations (HOA) treatment map.
Conclusion
It is this epithelial compensation mapping that allowed for the understanding of why treatment of corneal surface irregularity was often incomplete, especially over areas of significant corneal irregularity. The ability to effectively and accurately map epithelial thickness led directly to depth adjusted transepithelial PTK that reduces the masked HOA/corneal irregularity by performing a PTK to the depth of the thickest epithelium in the central 5 mm. Combined with topography-guided ablation, this has increased the amount of average total RMS HOA that is corrected in keratoconus from 32% to 60%, and in radial keratotomy surgically-induced corneal irregularity from 52% to approximately 70%. This adjusted PTK procedure can be used exclusive of topography-guided ablation, for example in cases of small central stromal aberrations such as a central island.
Manoj Motwani, MD, is a San Diego-based ophthalmologist and refractive surgeon with more than 25 years of experience in laser vision correction and corneal surgery. As medical director of Motwani LASIK Institute and Cornea Revolution, he specializes in advanced laser vision correction and the treatment of complex corneal conditions, including keratoconus, corneal ectasia, and irregular corneas. Dr. Motwani is also an active researcher and innovator, with multiple peer-reviewed publications and patents focused on improving corneal shape, visual quality, and refractive surgery outcomes.
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