Sequential decision making can lead us to a different clinical solution each time we reach into our contact lens toolbox. Take an emergent, unilateral keratoconus patient who has noticeable visual decline yet achieves 20/20 acuity. Which lens modality would be best suited for this patient?

A 34-year-old female presented with a chief complaint of long-standing decreased vision OS and a disheartening “I am not happy with my vision in my glasses” declaration. Corrected Snellen acuity with spectacle lenses (OD –1.50 sphere and OS –1.25 –1.25 x 145) was 20/20^-1 OD and 20/20 OS. She has no reported familial history of keratoconus, no previous ocular surgeries, no history of eye rubbing, and no ocular comorbidities. Noted OS are the abnormal anterior and posterior corneal elevation maps, reduced corneal thickness, and asymmetric curvature pattern with steep keratometric readings (Figures 1 and 2).

The Case for Hybrids

The debilitating visual noise—smearing of lights and difficulty seeing during rain storms—when driving at night was the number one motivator for this patient to improve the quality of her vision. In Figure 1, nearly a 5.00D jump in power is experienced across the pupil diameter, and it is evident that aberrations (mainly lower-order astigmatism and higher-order trefoil in Figure 3) are decreasing visual performance. The GP center of a hybrid lens can correct optical irregularity by using pooled tears beneath the back surface to fill in the crevices on the cornea. Optically, a hybrid lens can be a great option if no residual astigmatism is uncovered, as it cannot be incorporated into the lens power. For a young, first-time lens wearer, hybrids can provide a cost-effective, comfortable option to improve visual quality.

The Case for Custom Soft

Lathe-cut custom soft lenses can be an even more cost-effective visual aid compared to hybrids, depending on manufacturing and material selections. These are made to order, so toric powers can be incorporated. This modality largely uses increased lens thickness to mask irregularities on mildly irregular corneal surfaces. The thicker soft lens profile can decrease lens comfort, and sometimes you can end up chasing the prescription with a never-ending sphero-cylindrical over-refraction. It is important to consider this patient’s vocation (a nurse working night shifts). Less frequent replacement of this lens can promote noncompliance with care and handling. On the horizon are wavefront-guided optics that can also be incorporated to improve quality of vision.

Next Steps

Other than a short stint in which she attempted commercial soft lenses years ago but dropped out due to discomfort, this patient is a novice lens wearer. Either modality could work. Which would you choose? Check back in 2021 when I will report on the status of her fit. CLS