Article Date: 2/1/2011

Different Management Options for Keratoconus
MANAGING KERATOCONUS

Different Management Options for Keratoconus

If at first you don't succeed, these cases provide some examples of the many ways to manage keratoconus.

By Natalie Corey, OD, & Susan Kovacich, OD, FAAO

Keratoconus is a condition whose treatment can frustrate both patients and practitioners with its progressive and variable nature. Just when it seems that you have found a successful solution for a patient's visual needs, the cornea changes shape or vision deteriorates. In its early stages, keratoconus can be managed with standard contact lens options or even spectacles. However, as the disease progresses, the care of keratoconus will involve more challenges and specialty lens fits.

Following are several cases illustrating the variety of contact lens options that exist for varying stages of keratoconus and for patients who have specific ocular and visual needs.

Case 1

Our first case is a 31-year-old male who presented for his annual eye exam. Since being diagnosed with keratoconus five year ago, his off-axis, inferiorly positioned cones have not significantly impacted his vision. Previously he had been fit in Purevision Toric (Bausch + Lomb [B+L]) soft contact lenses. He reported that the contact lenses were comfortable and provided satisfactory vision.

The previous year, he had requested to be fit in GP lenses because he had heard that he would be able to see better with that type of lens. We fit him with large-diameter lenses due to his inferior cones. He was unhappy with both the Dyna Intra-Limbal (Lens Dynamics) and the MSD (Blanchard) lenses, noting significant visual ghosting with both designs. He elected to remain in the Purevision Toric lenses.

The patient presented wearing his Purevision Toric lenses: 8.7mm base curve (BC), 14.0mm diameter (Dia), +1.00 −2.25 × 040 OD and 8.7mm BC, 14.0mm Dia, +0.25 −1.25 × 110 OS. He achieved visual acuities (VAs) of 20/20- OD and OS. His simulated keratometry readings measured at 46.20/42.80 @ 026 OD and 45.10/43.60 @ 146 OS and proved to be relatively stable compared to the previous year's visit. Figure 1 shows his topography maps.

Figure 1. Case 1 topography maps OD and OS.

Because of his continued success, we determined that no change to his habitual soft toric lens fit would be made until the cornea changed and vision was impaired. This case demonstrates that patients with early keratoconus who have off-axis changes can often achieve success with a soft toric lens.

Case 2

A 22-year-old male presented with the complaint that the vision with his right lens was no longer clear. He had been diagnosed with keratoconus two years prior, and his cornea had been changing consistently since. His simulated keratometry readings at this visit were 45.40/44.30 @ 060 OD and 46.30/44.40 @ 122 OS. Figure 2 shows his topography maps OD and OS. He had been wearing a Boston ES (B+L) spherical lens in each eye. Both lenses fit flat on the cornea with apical bearing.

Figure 2. Case 2 topography maps OD and OS.

After steepening the BC of both lenses and adjusting the power based on the overrefraction, the new lenses fit with a feather touch on the apex of each cone and appropriate peripheral clearance. He achieved VAs of 20/20 OD and OS with Boston ES lenses in the following parameters: 7.58mm BC, 9.5mm Dia, −5.00D OD and 7.42mm BC, 9.5mm Dia, −4.75D OS.

Unfortunately, five months after this visit, the patient reported that the new left lens was starting to fall out of his eye. We again found it to be too flat and made appropriate changes to the BC. The new left lens had parameters of 7.33mm BC, 9.5mm Dia, −6.25D with 20/20 VA.

Despite his success in spherical GPs to this point, it may be necessary in the future to try a specialty design as his condition is progressing rapidly. However, this patient demonstrates the value of using a spherical GP design in the early stages of the disease.

Case 3

A 53-year-old male presented for an exam because he had lost his left lens, presumably due to a poor fit. He had been wearing the Rose K (Menicon/Blanchard) design for two years, and he had worn spherical GPs before that. The parameters of the Rose K lens were 6.93mm BC, 8.7mm Dia, −7.50D OD and 5.82mm BC, 8.7mm Dia, −15.50D OS. Both lenses were too flat and bearing on the corneas. The patient's corneas exhibited both Vogt's striae and Fleischer's ring, and his simulated keratometry values at this visit were 48.10/38.30 @ 062 OD and 44.90/41.80 @ 166 OS. Topography showed that his cones appeared to be decentered inferiorly and affected a large part of the corneal diameter in the inferior quadrant (Figure 3). Because of the large, sagging shape of the cones, we determined that a large-diameter lens might be more likely to result in a successful fitting relationship.

Figure 3. Case 3 topography maps OD and OS.

Rose K2 IC lenses (7.50mm BC, 11.2mm Dia, −4.00D OD and 8.04mm BC, 11.2mm Dia, −10.00D OS) resulted in bubbles in the periphery and seal-off at the edges of the lenses. We tried multiple other large-diameter lenses including the SO2 Clear (Dakota Sciences) and MSD lenses, but ultimately we determined that the best option for this patient was to refit the standard Rose K design with steeper base curve radii. The newest pair of Rose K lenses had parameters of 6.57mm BC, 8.7mm Dia, −8.25D OD and 5.50mm BC, 8.7mm Dia, −19.75D OS) and provided a stable fit with adequate vault of the apex and acceptable VAs. This case demonstrates that sometimes, a lens that may not be the best fit in theory may be the best option in practice.

Case 4

A 37-year-old female presented to the clinic because she wasn't achieving satisfactory vision through her soft spherical lenses. She wore spectacles over her soft lenses to correct her astigmatism. Her Acuvue 2 (Vistakon) lenses had parameters of 8.3mm BC, 14.0mm Dia, −10.50D OD and 8.3mm BC, 14.0mm Dia, −11.50D OS with a spectacle over-prescription of plano −1.00 × 045 OD and plano −1.00 × 140 OS and VAs of 20/70 OD and 20/60 OS. We graded her keratoconus as mild, as her simulated keratometry values were 46.60/45.30 @ 020 OD and 46.90/44.80 @ 168 OS. She had Fleischer's ring and Vogt's striae in both eyes and keratoconic topographies (Figure 4), but she had not been diagnosed with keratoconus prior to this visit.

Figure 4. Case 4 topography maps OD and OS.

Although the patient was initially reluctant to try GP lenses because of anticipated discomfort, she eventually agreed after learning of the potential benefits to her vision. It was decided that she would be fit in a large-diameter lens as larger diameters generally provide more comfort. We fit the Dyna Intra- Limbal lens. The initial lenses selected had parameters of 7.75mm BC, 11.2mm Dia, −11.50D OD and 7.75mm BC, 11.2mm Dia, −12.50D OS. After a few adjustments to the base and peripheral curve radii and power, we obtained a successful fit. More importantly, the patient was satisfied with the comfort and thrilled with the visual results.

The final lenses prescribed had parameters of 7.58mm BC, 11.2mm Dia, −12.00D with the peripheral curves (PCs) steepened by 2.00D OD and 7.58mm BC, 11.2mm Dia, −14.00D with PCs steepened by 2.00D OS and resulting 20/20 VA OD and OS. Although this patient presented with a mild case of keratoconus, a specialty fit proved necessary to accommodate the patient's desire for comfort and good vision.

Case 5

Our last case was a 51-year-old male who presented for his annual exam. He had been diagnosed with keratoconus about nine years ago and was a habitual SynergEyes A (SynergEyes) wearer. His SynergEyes lenses had parameters of 7.1mm BC, 8.4mm skirt curve (SC), 14.5mm Dia, −12.00D OD and 7.5mm BC, 8.8mm SC, 14.5mm Dia, −9.50D OS. Figure 5 shows his corneal topography OD and OS.

Figure 5. Case 5 topography maps OD and OS.

Recently, he had been diagnosed twice with microbial keratitis secondary to sleeping in his two-year-old lenses. After the ulcers healed, we determined that he needed to be refit into a different contact lens design to avoid further insult to the cornea in the areas of the ulcer scars.

Fortunately, at this time the SynergEyes ClearKone lens had become available. The reverse geometry design of the GP center allowed the midperipheral cornea to be spared further injury and provided the same visual results and acceptable comfort that the patient had experienced with his previous SynergEyes lenses. The ClearKone lens is not fit by base curve but by vault depth in microns. We successfully fit this patient with ClearKone lenses in parameters of 300µ vault, steep skirt, −12.00D OD and 200µ vault, steep skirt, −9.00D OS with 20/25- VA OD and OS. ClearKone is designed to completely vault the apex of the cone, making it a valuable lens design for any practitioners who wants to spare such patients from further corneal trauma.

Conclusion

When treating keratoconus with contact lenses, the important factors to consider are the visual outcome of each lens, achieving a fit that is healthiest for the cornea, and meeting each patient's own desires for vison and comfort. Table 1 summarizes different contact lens options available for managing keratoconus. As evidenced by these cases, numerous options are available for managing this condition. CLS

Dr. Corey graduated from the Indiana University School of Optometry in 2009 where she completed her residency in Cornea and Contact Lens in 2010. She currently is in practice in Westfield, Ind.
Dr. Kovacich graduated from Indiana University School of Optometry and completed a hospital-based residency at the St. Louis VAMC. In 1998 she returned to IU and is currently an associate clinical professor in the Cornea and Contact Lens Clinic. She has worked as a researcher and consultant for Allergan, Bausch + Lomb, Ciba Vision, and Vistakon.


Contact Lens Spectrum, Issue: February 2011