Overnight orthokeratology: visual and corneal changes

Area of Science:

• Ophthalmology
• Optometry
• Corneal Physiology

Background:

• Orthokeratology (OK) lenses offer a non-surgical method for vision correction.
• Reverse geometry OK lenses are designed for overnight wear to reshape the cornea.
• Understanding the time course and stability of visual and corneal changes is crucial for effective treatment.

Purpose of the Study:

• To achieve optimal fitting of reverse geometry Contex OK lenses.
• To determine the time course and stability of visual and corneal changes following overnight wear of OK B and D series lenses.
• To assess maximal refractive, corneal curvature, and corneal thickness changes.

Main Methods:

• A prospective study involving 10 subjects wearing OK B and D lenses overnight.
• Measurements included visual acuity, refractive correction, contrast sensitivity, corneal curvature, and thickness.
• Data collected at baseline, 1 day, 1 week, 1 month, and 3 months, with diurnal measurements post-lens removal.

Main Results:

• Significant overnight changes in visual acuity, refractive correction, contrast sensitivity, and corneal curvature were observed (P=0.01).
• Maximal visual and corneal changes were achieved by 1 week and remained stable throughout the day.
• Corneal epithelial thickness reduced by approximately 19 micrometers after 3 months of wear.
• Changes were sustained at 3 months.

Conclusions:

• Successful fitting of OK B and D lenses necessitates understanding the lens-cornea interaction.
• Full orthokeratological effect is achieved within one week of overnight wear.
• Stable visual and corneal changes provide excellent device-free vision throughout waking hours.