Article

CONTACT LENS CASE REPORTS

CORNEAL ELEVATION CAN GUIDE POST-TRAUMA FITTING

Sometimes the simplest things are what’s best for patients. A case in point is that of a 49-year-old welder who suffered a metallic puncture wound to his left eye in 2016. The patient was referred to our contact lens clinic for management of his irregular astigmatism. At the time of his initial presentation, the patient’s chief complaints were light sensitivity during the day and halos and ghosting at night with the left eye only.

The patient’s uncorrected visual acuities were 20/20 in the right eye and 20/50 in the left eye. Simulated keratometric readings were right eye 44.87/45.25 x 88 and left eye 44.37/44.12 x 115. Slit lamp examination of the right eye was within normal limits; however, an evaluation eye showed a 1.0 mm round scar just inferior and temporal to the line of the sight, the depth of the scar was approximately 250 um deep Figure 1. A manifest refraction of the left eye revealed +0.25 -1.50 x 060 20/25.

Figure 1. The patient’s left eye with a paracentral corneal scar secondary to a foreign body partial puncture wound.

Simpler than You Might Think

A closer examination of the patient’s left eye corneal topography (axial power display) showed mild oblique astigmatism within the pupillary margins. The elevation display map showed a minimal height differential (elevation to depression) of approximately 25 microns throughout the cornea. This indicates a relative “smoothness” to the corneal surface (Figure 2).

Figure 2. The left eye axial and elevation display corneal topography maps.

The patient was subsequently fitted in the left eye with an off-the-shelf toric soft contact lens that had parameters of 8.7mm base curve, 0.00 –1.25 x 060 power, and 14.5mm diameter through which he was able to see 20/30. With +0.50D over the top of the lenses, his visual acuity improved to 20/25. The patient reported that with the over-refraction, he had nearly complete resolution of the light sensitivity and ghosting. A new toric soft contact lens was ordered for the patient in parameters of 8.7mm base curve, +0.50 –1.25 x 060 power, and 14.5mm diameter.

Optical coherence tomography (OCT) imaging of the left eye showed the toric soft contact lens in place with a thickness of 143 microns. The central cornea showed a normal thickness of 516 microns. The scar depth was 267 microns, and there was an epithelial “plug” 114 microns deep that had formed over the scar (Figure 3).

Figure 3. OCT imaging clearly shows the slight depression over the site of the traumatic injury. The depression is secondary to a loss of stromal tissue. A 114-micron-deep epithelial plug formed to fill the void and “smooths” the ocular surface.

Elevation Matters

This case illustrates how the elevation display map can be used to better determine the “smoothness” of the corneal surface following a traumatic corneal injury. In this case, there was minimal corneal height differential (only 25 microns) between the highest and lowest portions of the cornea. Often, this indicates to us that the patient’s refractive error might be managed well with a simple (in this case toric) soft contact lens. CLS