Background: The appearance of the eyes can be altered with cosmetic contact lenses. These contact lenses are available with different central zone diameter.

Aim: To evaluate the visual acuity, contrast sensitivity and visual field among individuals wearing cosmetic contact lenses of various central zone diameter under mesopic conditions.

Materials and methods: A comparitive cross sectional study design was used. This study included 240 eyes of 120 individuals with age between 18-35 years. Data was collected at Alnafees Medical Hospital Islamabad. Visual acuity, contrast sensitivity and visual field were assesed using logmar chart, pellirobson chart and  bernell hand disc perimetry respectively. Participants were divided into two groups. Group A using the contact lenses with clear zone diameter of 5.5 mm. Group B using the contact lenses with clear zone diameter of 6.4 mm. The procedure beguns by applying mesopic conditions. Visual functions were measured before and after mesopic condition were applied. Data was analysed using independent sample T –test and Paired sample T-test.

Results: A statistically significant differences were observed in terms of visual acuity with a mean value of 0.1910 for group A and 0.065 for group B. Also for group A the mean value for contrast sensitivity, temporal visual field, nasal visual field, superior visual field and inferior visual field were 1.4873, 78.9583, 49.1250, 44.1667 and 67.1000 respectively. For group B the mean value for contrast sensitivity, temporal visual field, nasal visual field, superior visual field and inferior visual field were 1.7963,  88.2917, 56.8750, 52.9167 and 72.5417 under the mesopic light (P value=0.00).

Conclusion: The study concluded that in comparison to contact lenses with large optic zone diameters 6.4 mm, it was observed that visual acuity, contrast sensitivity, and visual field reduced significantly in contact lenses with small optic zone diameters 5.5 mm under mesopic condition.

Keywords: Contact lenses, contrast sensitivity, mesopic vision, visual acuity, visual field