A new 18-year-old male patient presented to our academic clinic with the goal of renewing his spherical soft contact lens prescription. He had no entering complaints other than occasional nonspecific dryness. He was a low myope, content with his vision correction. He reported good lens care habits, including rubbing with fresh solution daily, no overnight wear, and replacing his lenses monthly.

The contact lens evaluation was unremarkable, and his spherical contact lenses centered and moved well with blink. A full refraction revealed best-corrected visual acuities (BCVA) of only 20/20^-2 in each eye, but his previous records showed a BCVA of only one letter better a year and a half prior. Most practitioners wouldn’t think twice about a one-letter difference in BCVA, especially when the refractions were conducted by different eyecare practitioners (or by a student clinician in the second instance).

This patient also had a dryness complaint, and tear film instability can often result in a subtle decrease in visual performance. A slit lamp exam, however, showed that he had a good tear meniscus height, a stable tear film (tear break-up time was greater than 10 seconds), and no ocular surface staining or opacity. Suddenly, that one letter was a little more challenging to explain. Upon closer inspection, inferior thinning of a magnified corneal optic section beam was observed, so topography was ordered to investigate further.

Surprisingly, this patient had fairly advanced corneal ectasia. The photos in Figure 1 show areas of inferior corneal steepening, which is generally characteristic of keratoconus (Romero-Jiménez et al, 2013). Given that the patient’s steep keratometry reading was 56.4D in the right eye and 60.5D in the left eye, it was rather impressive that he rejected all cylinder and was corrected to 20/20^-2 with a spherical refraction. Also evident on the topography maps were areas of inferior corneal thinning (436µm and 476µm in the right and left eyes, respectively) and significant steepening of the posterior cornea.

The patient was educated about the nature of his condition and was cautioned to be cognizant of eye rubbing, as it can result in disease progression (Hassan et al, 2020; Sahebjada et al, 2021). It was at this time that he reported that he has always been a vigorous eye-rubber but didn’t really know why. The patient denied itching and assumed he must have “dry eye,” which explained the nonspecific complaint he gave at the start of the exam. This patient was kept in spherical soft contact lenses because he still maintained good vision with them, and was referred for a collagen cross-linking consultation in an attempt to increase the biomechanical stability of the corneas to slow disease progression (Godefrooij et al, 2020).

When patients miss a letter or two on the 20/20 line, it can be pretty easy to brush off, especially if dryness is reported and it happens to be an extra busy clinic day. Keep this case in mind when an explanation can’t be found at the slit lamp, such as contact lens deposits, poor tear film, or punctate keratitis, and investigate a little further. You never know what surprises may be in store. And, as with most ocular conditions, early detection often leads to improved patient outcomes. CLS

REFERENCES

1. Romero-Jiménez M, Santodomingo-Rubido J, González-Méijome JM. The thinnest, steepest, and maximum elevation corneal locations in noncontact and contact lens wearers in keratoconus. Cornea. 2013 Mar;32:332-337.
2. Hashemi H, Heydarian S, Hooshmand E, et al. The Prevalence and Risk Factors for Keratoconus: A Systematic Review and Meta-Analysis. Cornea. 2020 Feb;39:263-270.
3. Sahebjada S, Al-Mahrouqi HH, Moshegov S, et al. Eye rubbing in the aetiology of keratoconus: a systematic review and meta-analysis. Graefe’s Arch Clin Exp Ophthalmol. 2021 Aug;259:2057-2067.
4. Godefrooij DA, Roohé SL, Soeters N, Wisse RPL. The independent effect of various cross-linking treatment modalities on treatment effectiveness in keratoconus. Cornea. 2020 Jan;39:63-70.