Picking the right first patient

Start with the patient’s visual problem

The useful question is what the patient needs to improve. Poor quality vision in spectacles, irregular astigmatism and difficulty wearing rigid or scleral contact lenses are common reasons to consider CAIRS. Record refraction, uncorrected and corrected acuity, lens tolerance and the symptoms that matter to the patient.

A patient may read a reasonable line on the chart and still describe ghosting or poor visual quality. Equally, a striking topography does not automatically make a good first case. Discuss the intended improvement, the possibility of continued glasses or contact lenses, and the potential need for further treatment.

Choose a map you can explain

Start with reproducible tomography and a recognisable cone pattern. Review curvature and pachymetry together, and use an absolute colour scale when comparing severity between eyes. An automatically rescaled map can make a mild and a severe cone look deceptively similar.

Ask three questions from the first-case teaching:

1. Where is the cornea steep? Locate the steep region and its extent rather than relying on Kmax alone.
2. Does the pattern suggest one or two segments? An inferior or decentered cone and a more central, symmetric pattern may need different distributions of tissue.
3. How much tissue is appropriate? Use a nomogram that matches the preparation method and dimensions of the implant you intend to use.

For an early case, choose a plan that is straightforward to describe and reproduce. Markedly asymmetric cones, complex tapers and unequal paired segments add decisions that become easier with experience.

Leave the difficult cases until you have experience

Dr Gunn’s teaching highlights post-LASIK ectasia, very steep central corneas, very thin corneas and central apical scars as cases to avoid initially. These eyes may warrant CAIRS assessment by an experienced surgeon, but they add complexity to selection, channel placement and expectations.

That teaching slide uses central K above 60 D and CCT below 330 µm as beginner caution flags. These are first-case teaching points, rather than universal eligibility limits; central keratometry, Kmax, CCT and thickness along the planned channel are different measurements.

Inspect the ocular surface and address active surface disease, allergy and eye rubbing. Assess the cornea’s thickness along the whole proposed channel, alongside central and thinnest-point measurements.

Make the progression plan explicit

CAIRS aims to improve corneal shape and visual function. Review progression and decide separately whether and when cross-linking is needed. Document prior CXL because it can influence the cornea’s response, and discuss sequencing with the colleague helping you plan the case.