Contact Lenses

At the CPO level, contact lens work is mostly patient-facing: explaining what the doctor fit, reinforcing how to wear and care for it, and catching a compliance problem before it becomes a complication. The fitting math (base curve selection, vertexing, toric axis rotation) belongs to the doctor and the COT/COMT technician — the paraoptometric's job is to make sure the patient actually does, at home, what was prescribed in the chair.

Soft vs. rigid gas-permeable (RGP). Soft lenses are hydrogel or silicone hydrogel — flexible, comfortable almost immediately, and the large majority of new fits. Silicone hydrogel materials pass far more oxygen to the cornea (higher Dk/t) than older conventional hydrogel materials, which is why they dominate today's extended-wear and frequent-replacement lines. RGP (rigid gas-permeable) lenses are smaller, firmer, and take longer to adapt to — patients feel them for the first several days to weeks — but they deliver crisper optics for irregular corneas (keratoconus, high or irregular astigmatism, post-surgical corneas) and resist deposits better than soft materials. Scleral lenses, large-diameter rigid lenses that vault the cornea and rest on the sclera, come up for the same irregular-cornea and severe dry-eye population; patients need extra teaching on the insertion technique (filled with saline before insertion) since it differs from a standard lens.