Targeting Higher Order Aberrations Alone in Keratoconus: A Tissue-Saving Alternative to Established Protocols

Area of Science:

• Ophthalmology
• Corneal Surgery
• Refractive Surgery

Background:

• Keratoconus management often involves customized ablation strategies.
• Understanding the impact of different ablation profiles on corneal tissue is crucial for optimizing outcomes.
• Higher order aberrations (HOAs) play a significant role in visual quality for keratoconus patients.

Purpose of the Study:

• To evaluate cone stromal ablation depth with varying optical zones using different customized ablation strategies in keratoconus.
• To compare the efficacy of three distinct ablation approaches in terms of stromal tissue removal.
• To determine the effect of optical zone size on ablation depth across different treatment strategies.

Main Methods:

• Retrospective computational analysis of 59 keratoconus eyes.
• Simulated three ablation strategies: full manifest refraction + HOAs, Athens Protocol (70% sphere/cylinder + HOAs), and HOAs with embedded sphere/cylinder.
• Assessed mean stromal ablation depth and volume over the cone for optical zones ranging from 5.5 to 7 mm.

Main Results:

• Approach #3 (HOAs with embedded sphere/cylinder) demonstrated significantly lower mean stromal ablation depths and volumes compared to approaches #1 and #2 across all optical zones (P < .001).
• Approach #3 resulted in minimal increase in ablation depth with expanding optical zone size.
• Approach #1 yielded the highest ablation depths and volumes, followed by approach #2.

Conclusions:

• Customized ablation targeting only the sphere and cylinder embedded within the HOA profile results in the thinnest stromal ablation depth over the cone.
• This approach also minimizes the increase in ablation depth as the optical zone size expands.
• This strategy offers a promising method for keratoconus treatment with reduced stromal tissue removal.