51 YO female who had bilateral Penetrating Keratoplasties 30 years ago in Rotterdam – grafts have become ectatic and now exhibit signs of Rim Ectasia

This patient is a 51 YO female who had bilateral Penetrating Keratoplasties around 30 years ago in Rotterdam. Her grafts have become ectatic over the years and now exhibit signs of Rim Ectasia. This presents itself as a thinning of the host cornea leading to a tilting of the graft and a significant increase in irregular astigmatism.

Current Prescription

Her current spectacle prescription is:

R: -2.50/-6.50×50              6/7.5

L: +1.25/-12.75×125         6/7.5-

Her visual acuity with the spectacles is good, but her occupation as a paediatric doctor means her glasses are an inconvenience, and after seeing the corneal consultant, she was referred to me for a contact lens fitting. The amount of irregular astigmatism and the fact that the grafts are tilted forward superiorly means that corneal GPs, even in a post-graft design, would be unsuitable.

After a discussion with the patient, we decided to fit some mini-sclerals; she had previously worn full 22mm sclerals at some point in the past and was receptive to the idea of mini-sclerals.

Initial fitting appointment 16/4/21

Trial with OneFit Med, No7 Contact Lenses.

Several lenses were trialled before a pair of lenses was found which cleared the cornea in both eyes. The image below shows one of the lenses trialled with excessive clearance over the whole cornea; it does, however, illustrate the extent of the rim ectasia in this patient.

Finally, the 5450μ lens for the RE and the 5750μ for the LE were used.

The lenses were allowed to settle for 40 minutes before over-refraction, and then OCT scanning was conducted using the MS-39 AS-OCT from CSO Italia, which has a 16mm image size and can image the full diameter of the lens in situ.

The OCT images showed central clearance of R 175 μ and L 200 μ however, there was a significant amount of touch in the 12 O’clock position on both eyes L>R.

The flat axes of the toric periphery aligned with the corneal astigmatism at R 120º and L 40º and were tight along these axes.

The lenses needed to have increased height at the areas of superior touch; with the OneFit Med this is achievable in two zones at 9.5mm and 12.5mm; the clearance at 12.5mm was good so the M or mid-peripheral zones height would need to be increased by 100μ in each eye. The toricity would also need increasing; using the online calculator, the new parameters were calculated as follows:

R 5450μ -10.62/-1.50×120 200μ TP M +100μ

L 5750μ -13.12/-2.50×40   200μ TP M + 100μ

It is especially important to keep the central clearance as low as possible to maximise the oxygen reaching the cornea. For this reason, the lenses were manufactured in the Optimum Infinite material with a 180 Dk to minimise the possibility of hypoxia and possible corneal de-compensation.

Collection appointment 24/5/21

AS-OCT showed no touch with 200μ of clearance centrally and 80μ of clearance at the M zone.

Px was then instructed on insertion and removal and issued with Hy-Care, Saline, case and instructed to build up wearing time by 1 hour/day to a maximum of 10 hours until the next visit.

Follow-up visit 21/6/21

Wearing time today 4 hours

Scanning the patient with AS-OCT showed that the right lens had settled back and was now touching the superior cornea at approximately 2 o’clock slightly inside the central zone of the lens; this also caused some edge lift off superiorly.

Some increase in superior clearance was needed without increasing the central clearance due to hypoxia concerns with a thick fluid layer over the graft. OneFit Med has a reverse geometry option called Central Clearance Reduction (CCR), which flattens the base curve of the optic zone diameter. In this instance by using CCR, the flatter base curve lifts the lens away from the protruding graft and has the added effect of reducing some of the high minus in the lens power.

The calculator was used to produce the new lens specification taking into account the over-refraction and CCR on the right lens.

Collection appointment 27/7/21

The patient was again instructed to build up the wearing time gradually by 1 hour per day to a maximum of 10 hours and 4-5 days/week.

Follow-up appointment 15/9/21

The patient had built up the wearing time to 5 hours per day 5 days a week which suited her working schedule. The lenses were fitting well with no adverse effects; she was put on a 3 month recall, sooner if any issues or concerns.

Follow-up appointment 17/1/22

The patient is still happy with her lenses and is able to use them while exercising and scuba diving as well as some time at work; she finds her eyes become slightly red at about 7-8 hours so limits her time to less than that.

The lenses are still clearing the cornea fully, no touch was observed in any meridian.

The corneal consultant has also seen the patient and is happy with her corneal health, she will be seen on a six-monthly review schedule in the contact lens clinic with the option for me to refer her to the corneal clinic if there are any concerns.

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