During this session, interns should familiarize themselves with the techniques of hygiene and care, insertion, removal and recentering of lenses. A videotape showing patients fit with different base curves and corresponding fluorescein patterns will be viewed. Interns will attempt to achieve a successful fit on their partners. If time permits, they should fit their partners with lenses of different base curves to determine what effect the lens base curve has on the physical fit and ocular refraction.

Diagnostic contact lens set and accessories – cleaning, soaking and wetting solutions, irrigating solution, fluorescein strips, Burton Lamps and Biomicroscope.

1. Practice the techniques of handling, inserting, removing and recentering of lenses demonstrated by your instructor. Once you have perfected these techniques, proceed to fit your partner.
2. Using previously obtained Central K readings for your partner, use the following base curve selection and evaluate the fit of the lenses (see data sheet):

0.75-1.00D 0.25D-0.50D flatter than low K

1.25D-1.50D "K" to 0.25D flatter than low K

1.75-2.00D 0.25D steeper than low K

2.25-2.50D 0.50D steeper than low K

2.75-3.00D 0.50D-0.75D steeper than low K

Tetracurve Design Tricurve Design

SCR/W = BCR + 0.8mm/.2mm-.3mm SCR/W = BCR + 1mm/.3mm

ICR/W = SCR + 1.0mm/.2mm PCR/W = SCR + 2mm/.3mm

PCR/W = ICR + 1.4mm/.2mm

Place lenses on both eyes and allow 15 minutes for tearing to subside before evaluating the fit.

1. Evaluate the lens performance in terms of centration and lag.
2. Instill fluorescein and observe the tear pattern under each lens, both in the static and dynamic state. Draw the pattern for each zone of the lens. (central, intermediate and peripheral).

Is the overall pattern toric in shape? If so, is it with the rule, against the rule or oblique astigmatism? Indicate by drawing.

1. Repeat the evaluation of the lens performance with the slit lamp.
2. Observe the lens-cornea relationship with the cobalt filter and parallelepiped.

All data should be entered on the evaluation sheet provided.

Each student must demonstrate proficiency in handling, inserting, removing and centering of lenses before proceeding to designing and ordering lenses for his or her partner. In addition, complete the predicted over-refraction and Rx sections of the exercise to turn in with the completed fit and order form one week after the last fitting lab. *This order will not actually be ordered for y our partner.