[Visual acuity at twilight and contrast vision in patients with bifocal IOL]

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optics

Background:

• Cataract extraction with phacoemulsification is a common surgical procedure.
• Bifocal intraocular lenses (IOLs) aim to restore both distance and near vision.
• Evaluating the performance of different bifocal IOL models is crucial for patient outcomes.

Purpose of the Study:

• To compare the visual performance of the True Vista bifocal lens and the Accurasee bifocal lens.
• To assess visual acuity, mesopic acuity, and contrast thresholds under mesopic conditions.

Main Methods:

• Phacoemulsification followed by implantation of either True Vista (Group I, n=20) or Accurasee (Group II, n=14) bifocal IOLs.
• Postoperative assessment at 4-6 months included distance and near visual acuity (uncorrected and corrected).
• Mesopic visual acuity and contrast thresholds were measured using the Mesoptometer II under varying light and glare conditions.

Main Results:

• Both IOLs provided comparable distance and near visual acuities without correction.
• Mean distance acuity: True Vista 0.77, Accurasee 0.73.
• Mean near acuity: True Vista 0.84, Accurasee 0.85.
• Mesopic visual acuity was similar for both lenses (True Vista 0.25, Accurasee 0.26).
• True Vista demonstrated a slight advantage in contrast thresholds under specific glare conditions (0.032 and 0.1 cd/m2).

Conclusions:

• The True Vista and Accurasee bifocal IOLs offer comparable visual outcomes in terms of distance and near acuity.
• Mesopic visual performance is similar between the two lens types.
• The True Vista lens may provide a marginal benefit in contrast sensitivity under challenging glare conditions.