Scheimpflug-Derived Corneal Lower and Higher Order Aberrations Post Intrastromal Corneal Ring Segments for...

Area of Science:

• Ophthalmology
• Corneal Surgery
• Visual Optics

Background:

• Keratoconus is a progressive corneal ectasia leading to irregular astigmatism and visual distortion.
• Intrastromal corneal ring segments (ICRS) are used to regularize the corneal surface and improve visual acuity in keratoconus.
• Understanding the impact of ICRS on visual aberrations across different pupil sizes is crucial for surgical outcomes.

Purpose of the Study:

• To evaluate the changes in lower-order aberrations (LOAs) and higher-order aberrations (HOAs) after ICRS implantation in keratoconus patients.
• To investigate the influence of varying pupil sizes (6 mm, 4 mm, 2 mm) on these aberration changes.
• To determine the effect of ICRS on total corneal HOAs up to the 6th order.

Main Methods:

• Prospective interventional study including 21 eyes with keratoconus undergoing ICRS implantation.
• Corneal aberrations (LOAs and HOAs) measured preoperatively and at 6 months postoperatively.
• Measurements taken using Zernicke analysis on a Scheimpflug device at 6 mm, 4 mm, and 2 mm pupil diameters.

Main Results:

• ICRS implantation significantly reduced vertical coma at 4 mm (p=0.015) and 6 mm (p<0.001) pupil sizes, with no effect at 2 mm.
• Significant reductions in horizontal coma, astigmatism, and trefoil were observed at 4 mm or 6 mm pupil sizes, but not at 2 mm.
• Root Mean Square (RMS) of HOAs also showed significant reduction at larger pupil sizes.

Conclusions:

• ICRS implantation favorably impacts HOAs, especially in larger pupil sizes.
• Pupil size is an important factor correlating with the reduction of HOAs after ICRS surgery.
• ICRS serves as a viable option for improving visual quality in keratoconus by reducing corneal aberrations.