Compression Factor and Visual Performance in Adults Treated With Orthokeratology

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Orthokeratology (ortho-k) is a non-surgical refractive correction method using rigid gas permeable lenses worn overnight.
• The compression factor of ortho-k lenses influences corneal reshaping and refractive outcomes.
• Understanding the impact of different compression factors is crucial for optimizing ortho-k therapy.

Purpose of the Study:

• To evaluate the effect of varying compression factors in ortho-k lenses on visual performance and higher-order aberrations (HOAs) in myopic adults.
• To compare subjective visual satisfaction and objective visual acuity between different ortho-k lens compression factors over 12 months.

Main Methods:

• Myopic adults were fitted with ortho-k lenses having either 0.75 D (conventional compression factor, CCF) or 1.75 D (increased compression factor, ICF) compression.
• Measurements included higher-order aberrations, corneal topography, visual acuity (high- and low-contrast), subjective refraction, and quality of life questionnaires.
• Data were collected at baseline and at multiple follow-up points up to 12 months.

Main Results:

• Both compression factors significantly improved vision satisfaction after waking compared to before sleep.
• The ICF group showed a trend towards less myopia and better high-contrast unaided visual acuity at early follow-up points.
• No significant differences were found in treatment zone diameter, lens decentration, or overall subjective measurements between the groups.
• Certain individual higher-order aberrations were elevated in the CCF group, but the overall HOA visual Strehl ratio decreased similarly in both groups after lens wear.

Conclusions:

• Increased compression factors in ortho-k lenses do not lead to clinically significant differences in refractive outcomes, visual acuity, or overall higher-order aberration profiles compared to conventional factors after long-term wear.
• Ortho-k lens wear generally enhances vision satisfaction, irrespective of the compression factor used.