This case involves a keratoconus patient who developed an erosion from a special keratoconus design GP lens that subsequently resulted in apical touch. The image above shows a staining pattern in the central cornea with an erosion at the keratoconus apex.
During a follow-up visit in February 2011, the patient complained of occasional eye pain and less tolerance to lens wear in the right eye only. She was wearing the lens from 10 to 12 hours per day, and visual acuity (VA) was 20/30+2 despite the discomfort. She is a long-term patient at our clinic Instituto de Olhos Dr. Saul Bastos; my father started treating her back in the 1990s.
Topography OD showed a mild progression, and the keratoconus GP lens fit was presenting with slight apical touch with a nipple cone pattern. We do not accept three-point-touch fitting for keratoconus. Rather, we always promote no apical touch or no touch at all, with free lacrimal film under the lens. We also observed a significant drop in the tear breakup time of two to three seconds. We asked the patient to suspend lens wear for at least two to three days and then to return for a refit.
She told us that she was too busy at that time, so she would not be able to stop lens wear. We insisted that this was important; she promised to wear the lens for only eight to 10 hours a day and to use artificial tears every two hours. She would then return for a new fit in three months after not wearing the lens for at least two days.
You can see in Figure 2 a light apical touch and the nipple pattern, which was not presented before in her history. This pattern was found two years prior to the apical erosion. We usually evaluate the lens behavior on the eye to protect the cornea, so the patient was instructed and informed about the need for a new fit. She assumed responsibility to come back as soon as possible.
Previous lens parameters OD were:
61D x 45D base curves, 9.8mm overall diameter (OAD), 5.8mm optic zone (OZ), -14.50D power, Paragon HDS 100 material.
The patient returned for a second follow-up exam 20 days later, still presenting the erosion at the apex. We instructed her to treat the cornea with Epitezan (Allergan, not available in the United States) t.i.d. and also to apply nonpreserved eye drops throughout the day and then to return after 10 days of treatment. At that visit, the cornea was significantly healed; however, we suspect that she may have worn the lens a few times even though she said she did not. Figure 3 shows the fluorescein pattern after the treatment.
We agreed to refit the same keratoconus GP lens design with different parameters to vault the corneal apex and help the cornea remain in good physiological health.1 The patient was instructed to apply Hylo Gel (CandorVision, not available in the United States) t.i.d. during lens wear. Figure 4 shows the new customized keratoconus lens planned to correct the fitting. The cornea presented central leukoma, and the VA obtained was 20/25+1 OD, with vision improvement.
The new keratoconus lens parameters OD were:
63D x 45D base curves, 10.5mm OAD, 6.5mm OZ, -16.50mm power, HDS 100
I find it quite disappointing when I hear speakers still promoting the three-point-touch fitting technique for keratoconus. It is possible to sometimes achieve a good fit with this technique, depending on the epithelial structure, lens mass, good weight distribution, and centration; however, it is too risky. Corneal GP lenses have to exhibit some movement, so if there is apical touch, that means there is friction to an already fragile structure. Continued wear of such lenses can lead first to damaged epithelium, then Bowman’s layer, and, finally, it may lead to more serious complications. Theoretically, if the lens shows no movement, it will not induce friction and damage to the central cornea, but this may lead to lens adherence. When such lenses do not move, lacrimal exchange or the tear pump practically does not exist. The problem is a lack of lubrication.
In that case, a lens with no movement may induce other problems created by lack of tear film under the lens and over the corneal epithelium. We strongly believe that lacrimal exchange and also a small pool of tears will always help the cornea to maintain its physiological health.
In some cases, patients will say that they prefer a lens with apical touch because the visual outcome and maybe VA is better; in such cases, it is important to make sure that patients understand the risk involved.
The goal of fitting GP lenses slightly steeper than the central cornea is to restore visual acuity. There is no evidence that GP lens wear may stop or retard keratoconus progression. On the contrary, if there is touch, the cornea may be affected in a harmful way that could lead to corneal thinning or eventually contribute to the already weak corneal biomechanical resistance in keratoconus.2 We have observed that the patients who are fit with the non-touch technique have a much safer and more stable condition compared with those who suffer with poor fitting or poor quality GP lenses.
- Reed K. Keratoconus: Polish Your Skills. Rev Optom. 2001 Oct 15;138:10. Available at https://www.reviewofoptometry.com/article/keratoconus-polish-your-skills . Accessed on May 30, 2017.
- Kent C. Measuring Ocular Biomechanics. Rev Ophthalmol. 2006 Dec 15. Available at https://www.reviewofophthalmology.com/article/measuring-ocular-biomechanics . Accessed on May 30, 2017.